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Effects of rumen-protected carbohydrate supplementation on performance and blood metabolites in feedlot finishing steers during heat stress

Effects of rumen-protected carbohydrate supplementation on performance and blood metabolites in... Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Effects of rumen-protected carbohydrate supplementation on performance and blood metabolites in feedlot finishing steers during heat stress † ‡ ||,1, Juan P. Russi, Nicolas DiLorenzo, and Alejandro E. Relling † ‡ RUPCA LLC, Merced, CA 95340; University of Florida, North Florida Research and Education Center, || Marianna, FL 32351; and Department of Animal Sciences, Ohio State University, Wooster, OH 44691 ABSTRACT: The objective of this experiment Mixed, SAS) using treatment, time, and their inter- was to evaluate the inclusion of a rumen-pro- action as a fixed variable and pen as a random var - tected carbohydrate (RPC) on growth perfor- iable. There were no differences (P > 0.10) between mance and blood metabolites of finishing steers the three treatments on CPS, BF, and LM area on during the summer. A 62-d feedlot study was con- day 62. There was a trend (P = 0.06) for treatment ducted using 135 Angus crossbred steers (body effect for a greater body weight on the 0.5RPC, and weight = 287 ± 13 kg). All animals were fed a basal a treatment effect for dry matter intake (P = 0.05). diet (BD), then treatments were top-dressed. The Treatment × day interactions were observed for treatments were the same composition and only var- average daily gain (ADG, P =0.04), suggesting a ied in ruminal degradability. Treatments were 1) a different response to treatments during the differ- BD with 1 kg/d of a control supplement (0RPC), ent sampling periods. There was a treatment effect 2) the BD plus 0.5 kg/d of the control supplement for blood glucose concentration (P = 0.03), having and 0.5 kg/d of RPC (0.5RCP), and 3) the BD with the 0RPC the greatest concentration. Treatment 1  kg/d of RPC supplement (1RPC). Temperature × day interactions were found for plasma insulin humidity index and cattle panting scores (CPS) concentration (P  =  0.01). The results suggest that were measured daily during the experiment. Growth the response to RPC supplementation depends in performance, back-fat over the 12th rib (BF), LM part on environment. The use of 0.5 kg/d of RPC area, blood glucose and plasma insulin, urea, and tends to improve overall body weight; however, the nonesterified fatty acid concentrations were meas- response to RPC on ADG and plasma insulin con- ured. Data were statistically analyzed (PROC centration depend on the time of sampling. Key words: blood metabolites, glucose, heat stress, protected carbohydrate © The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Transl. Anim. Sci. 2018.XX:XX–XX doi: 10.1093/tas/txy122 (ADG) (Mader et al., 2006). Several management INTRODUCTION strategies can be adopted to mitigate the effect of Maintaining an increased growth rate in feed- heat stress, such as the use of shades and sprin- lot steers during periods of heat stress can be chal- klers (Gaughan et  al., 2010). Altering feed deliv- lenging. Weather conditions can drastically affect ery patterns (Mader, 2003), or the amount of feed dry matter intake (DMI) and average daily gain delivered, or diet energy concentration can also be beneficial (Mader and Davis, 2004). Decreased DMI is not the only concern during Corresponding author: relling.1@osu.edu heat stress, but loss of production may also occur Received September 10, 2018. Accepted November 9, 2018. because the animal is metabolically challenged. 1 Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 2 Russi et al. For instance, in dairy cows only 30% to 50% of the procedures were approved by the Animal Care and reduction in milk production during heat stress can Use Committee from Veterinary College (Energy be explained by the diminished DMI (Rhoads et al., metabolism in beef cattle, 4 April 2011)  and La 2009). In growing bull calves exposed to heat stress, Plata National University. the decrease in growth performance can entirely be attributed to a decrease in DMI (O’Brien et al., Animals, Treatments, and Sampling 2010). Despite the different animal models, blood One hundred thirty-five (average body weight and plasma metabolite concentrations follow simi- [BW]  =  287  ±  13  kg) Angus crossbred steers were lar patterns. Even with the decrease in DMI during used in a 62-d experiment. Steers were blocked by heat stress, plasma glucose and nonesterified fatty BW and assigned to one of three treatments in a acids (NEFA) concentration are decreased and randomized complete block design with five pens insulin concentrations are increased (Baumgard per treatment. Steers were given ad libitum access to and Rhoads, 2012). the basal diet (BD). Treatment was top-dressed and Glucose concentration in blood had increased the treatments were as follows: 1) 1 kg/d of control by infusing starch or glucose into the abomasum supplement (0RPC), 2) 0.5 kg/d of control supple- (Kreikemeier et  al., 1991). Efficiency of conver - ment and 0.5 of kg/d RPC (0.5RPC), and 3) 1 kg/d sion of starch energy into tissue energy is improved of RPC (1RPC). The diets were formulated to when starch is digested in the small intestine rather meet or exceed requirements for beef (NRC, 2000). than fermented in the rumen (Harmon, 1992). Both the control supplement and RPC supplement But due to the rumen physiology, the use of a contained (% DM) the same ingredients (Table  1), rumen-unprotected glucose source is fermented in differing only in the processing of the carbohy- the rumen. Also there might be limitations in the drate. Rumen protection of RPC and its small amount of starch that the small intestine can digest intestine absorption had been tested and described (Branco et al., 1999). For example, in growing and on the patent of the product (U.S.  patent number finishing steers, Huntington et  al. (2006) showed 8,507,025). The target amount of protected dex- that approximately 700  g/d of starch seems to be trose for each treatment was 0, 180, or 360 g/d for the limit for starch digestion in the small intestine. 0RPC, 0.5RPC, and 1RPC, respectively (Table 1). Any excess of that amount would pass undigested Fifteen days before starting the experiment, contents to the lower gastrointestinal tract. This BW was recorded. Steers were stratified by BW may be because of a decrease in α-amylase secre- and used to establish the blocking weight criteria. tion by the pancreas (Walker and Harmon, 1995). Therefore, a rumen-protected glucose might be Table  1. Composition and chemical analysis (on beneficial. However, there are no studies that show DM basis) of basal diet and RPC or supplement the effect of protected glucose on feedlot perfor- mance on summer time condition. Ingredients Basal diet Suplement or RPC Based on the cited literature, we hypothesize Corn silage, % 16 – that feeding rumen-protected carbohydrates (RPCs) Dry-rolled corn, % 81 – will improve growth performance in heat-stressed Soybean meal, % – 58.1 animals. The objective of this study was to evalu- Dextrose, % – 38.9 Urea, % 0.55 2.8 ate the inclusion of a RPC on growth performance, Vitamins and minerals , % 2.25 – blood glucose, and plasma insulin and NEFA con- Mineral salts , % – 1.2 centration in finishing steers during summer. Diet DM,% 57.5 85.7 CP, % DM 10.1 27.8 MATERIALS AND METHODS ADF, % DM 14.9 14.4 NDF, % DM 31.7 28.8 Facilities EE, % DM 2.9 4.5 Ash, % DM 4.4 2.8 The experiment was conducted in a commer- The supplement and RPC differed only in the processing of the cial feedlot located in Buenos Aires, Argentina carbohydrate (i.e., protected or not from ruminal degradation). (lat.: 34°43′14″ S, long.: 63°05′08″ W), during the Minerals: Ca 27.74%, Mg 0.62%, Na 9.26%, Co 6.17  ppm, Cu summer of 2013–2014 (December, January, and 555 ppm, I 30.86 ppm, Mn 2037 ppm, Se 18.52 ppm, Zinc 2592 ppm, February). Fifteen soil-surfaced pens (12  ×  50 Monensin 1.03%. m) were used with nine steers in each pen. Water Mineral salts: Na bicarbonate 35  g, K HPO 6  g, KH PO 4.5  g, 2 4 2 4 ClNa 10 g. troughs were shared between two pens. All animal Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 3 Five blocks were assigned by weight, nine animals 1,000 × g to obtain plasma which was immediately per pen. frozen and stored at −20°C until analyzed for insu- Individual BW were scheduled to be obtained lin, NEFA, and urea. Whole blood glucose concen- on days 1, 15, 36, and 57. Day 15 was the end of trations were determined in situ with a glucometer the adaptation period and then every 21 d; how- (Optimum Xceedt, ABBOTT Lab Argentina). The ever, due to weather conditions (rainfall during the plasma insulin concentration was analyzed via radi- scheduled day), the actual BW was measured on oinmuno assay as described previously (Díaz-Torga days 1, 15, 39, and 62 relative to the starting day et  al., 2001). The minimum detectable concentra- (day 1). Animals were individually weighed before tion was 0.05 ng/mL. Intersample and intrasample the morning feeding. coefficients of variation were 8% and 7%, respec- Feed was offered daily and refusals were col- tively. Plasma NEFA concentration was analyzed lected once a week (days 8, 15, 23, 29, 33, 36, 44, 49, on days 0, 15, 39, and 62, using a colorimetric 54, 58, and 62) to determine DMI. The DMI obser- assay, following the protocol described by Randox vations on days 1 and 15 correspond to the adap- labs (FA 115 Randox Laboratories Ltd.). The min- tation period to the diet, and from day 16 onwards imum detectable concentration was 72  mM, and the steers were fully adapted to the final diet. the intrasample and intersample coefficients of Steers were adapted to the final diet during the variation were 7.5% and 23%, respectively. Plasma first 15 d of the experiment in three stages. The urea-N concentrations were analyzed on days 0, 39, first stage lasted for 5 d and the diet contained 60% and 62, using the colorimetric protocol described corn silage, 30% dry-rolled corn, 7.5% sunflower by Wiener Lab city (Rosario, Santa Fe, 2R UREA seed meal, 0.5 urea, and 2% of mineral and vitamin Color). The minimum detectable concentration mix with monensin (on DM bases). From days 6 to of urea was 2  mg/dL. Coefficients of variation of 11, the diet contained 53.5% corn silage, 43% dry- intrasamples and intersamples were 9.7% and 11%, rolled corn, 0.5% urea, and 2% of a mineral vita- respectively. min mix with monensin (on DM bases) and at this Temperature and humidity were recorded every stage, 0.5 kg of supplement or RPC was added as 30 min during the entire experiment by a meteoro- top-dress. From days 11 to 15, the diet contained logical station (Davies instruments, San Francisco, 37% corn silage, 60% dry-rolled corn, 0.6% urea, California) placed in the city of Piedritas 14 km and 2.4% of a mineral vitamin mix with monensin from the feed yard (Longitude 62°58′49″ W; lat- (on DM bases), 1 kg of supplement, RPC or half itude: 34°33′58″). Temperature humidity index and half was added as top-dress. From days 16 to (THI) was calculated according to Hubbard et  al. 62, end of the experiment, the animals were fed the (1999), using the following equation: THI = (0.8 × final diets as described in Table 1. temperature) + [(%  relative humidity/100) × (tem- Once in a week, individual feed ingredient perature − 14.4)] + 46.4. samples were taken and composite to be analyzed Daily average, maximum, and minimum THI for nutrient composition at the end of the experi- values were calculated for all the experimental peri- ment. Feed samples were analyzed for DM (60°C ods. Also, partial THI values were calculated for for 48  h), ADF and NDF (Ankom Technology the periods when the animals were weighed: period methods 5 and 6, respectively; Ankom Technology, 1 (days 1 to15), period 2 (days 16 to 39), and period Fairport, NY), CP (method 930.15; AOAC, 1996), 3 (days 40 to 62). ether extract (method 2; Ankom Technology, Cattle panting scores (CPS) were recorded from Fairport, NY), and total ash (600°C for 12 h). days 1 to 62, end of the experiment, between 1200 Back-fat at the 12th rib (BF) and LM area and 1600 h, as well as the time at which the obser- were measured by ultrasound on days 0 and 62 (Pie vation was taken. CPS were classified as described Medical mod. Aquila. Transductor 3.5 mhtz). by Mader et al. (2006) on a 0 to 4 scale with 0 being Blood samples were taken from the same four normal and 4 being severe open-mouthed panting animals, randomly selected at the start of the trial, accompanied by protruding tongue and excessive from each pen via jugular vein puncture before the salivation, usually with neck extended forward. For morning feeding. A drop of blood was used for glu- the correlation between CPS and THI, only days cose analysis and the rest of the blood was placed with a THI > 70 were taken into account, and this in tubes containing disodium EDTA (1.6  mg/mL included 29 of 62 d of the experiment. of blood) on days 0, 15, 39, and 62. Samples were Daily average THI measured was 72 ± 4.9 with maintained in a cooler until collection was finished. a maximal THI of 79 and a minimal THI of 59. Blood samples were then centrifuged for 20 min at Animals experienced THI over 70 for 46 d of the Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 4 Russi et al. THI THI 70 79.3 78.6 76.0 62.8 Avg. . THI: 71.9 Avg..THI: 70.7 Avg..THI: 72.9 60.9 Max THI: 79.3 Max THI: 76 Max THI: 78.6 59.5 Min THI: 59.4 Min THI: 62.8 Min THI: 60.8 Days <70THI: 10 de 24 Days <70THI: 8de 23 Days<70THI: 3 de15 Perriod1 Period 2Period 3 -2 26 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 Days Figure 1. THI across days on the experiment. Marked on the figure is the THI 70 and periods 1 to 3 organized to match sampling of perfor - mance and blood metabolites. 62-d experiment (Figure  1). When THI was sliced separate means when the time × treatment interac- into periods to match BW measurements (days 0 to tion was different (P < 0.10), and mean compari- sons were conducted using the PDIFF statement 15, 16 to 39, and 40 to 62), no statistical differences of SAS whenever there was only a main effect or a were observed on average THI amongst the three treatment effect for a particular day after the use of periods (P = 0.40). the SLICE option. The PROC Corr of SAS, version 9.4 (SAS Statistical Analysis Institute, Inc., Cary, NC), was used to evaluate cor- relation between THI and CPS and CPS and time Data were analyzed as a randomized complete of the day when the observation was reported. block design with repeated measurements, using the MIXED procedure of SAS, version 9.4 (SAS RESULTS Institute, Inc., Cary, NC). The model included the fixed effect of treatments, days (time), and interac- There was no correlation between THI and CPS tions between treatments and days, and the random (r = 0.18, P = 0.35) during the experiment. Despite the effect of pen and block (BW). Days was consid- lack of correlation between THI and CPS, CPS was ered as the repeated statement. Pen was consid- above 1 (on every steer) on the 29 d where THI was ered as the experimental unit. Block was removed greater than 70. from the model when it was not significant (P > No treatment × day interaction were observed 0.1). The covariance structures compared included for BW, but animals fed 0.5RPC and 1RPC had compound symmetry, unstructured, spatial power, a tendency for treatment effect (P  =  0.06) to have autoregressive, and heterogeneous autoregressive. a greater BW than 0RPC (Table  2). There was a Dependent variables were analyzed using the covar- treatment × day interaction (P  =  0.04, Figure  2) iance-structured spatial power, because it gave the for ADG. In period 2, steers fed 0.5RPC reported best fit based on the Akaike information criterion the largest ADG of 1.42 kg/d followed by the steers (Littell et al., 2006). Back fat thickness at the 12th fed 1RPC with 1.23 kg/d and the steers fed 0RPC rib and LM area on day 62 did not have repeated 1.13 kg/d, but there were no differences at the end measurements, and the initial value on day 1 was of the experiment on the total ADG comparing the used as a co-variate. The slice option was used to animals fed the three treatments (Figure  2). There Translate basic science to industry innovation THI Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 5 Table 2. Effect of increasing dose of RPC on DMI, BW, back fat (BF) at 12th rib on 63 d and Longissimus muscle (LM) area on day 62 in finishing steers during heat stress. Treatment (Trt) P-value Item 0RPC 0.5RPC 1RPC SEM Trt Day (d) Trt × d Initial BW, kg 281 285 284 1.6 0.06 <0.01 0.76 Final BW, kg 350 355 352 a ab b DMI, kg/d 9.8 9.9 10.1 0.07 0.05 <0.01 0.14 BF, cm 0.59 0.6 0.6 0.015 0.82 – – LM on day 62, cm 57.39 54.56 56.56 0.967 0.15 – – NEFA concentration was not different amongst the 1.6 steers fed the different treatments (P = 0.15, Table 3). 1.4 1.2 DISCUSSION 0RCP 0.8 Diets were designed to be isoenergetic and 0.6 0.5RPC isonitrogenous. All treatments received the same 0.4 1RPC amount of dextrose (360 g) and the difference was 0.2 in the ruminal protection of the carbohydrate. In 0RPC, none of the 360  g of dextrose were pro- 15 39 62 tected from ruminal degradation and all of the sol- Days uble carbohydrates were assumed to fuel microbial Figure  2. Effects of increasing dose of RPC on ADG in finishing growth in the rumen. In 0.5RPC, only 180 g of dex- steers during heat stress. The dotted line represents the daily THI. 0RPC steers received the basal diet plus 1  kg/d of supplement top dressed trose were protected and 180  g were unprotected, (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts and cattle fed 1RPC received 360 g of rumen-pro- DM basis, without the ruminal protection). 0.5RPC steers received the tected dextrose (Russi et al., 2011). basal diet plus top dressed 0.5 kg/d of supplement and 0.5 kg/d of RPC Period 1 lasted for 15 d and had an average THI (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts DM basis, with ruminal protection). 1RPC steers received the basal diet of 72.9  ±  5 with a maximum and minimum THI plus 1 kg/d of RPC. Data are presented as least square means and SEM. of 78.6 and 60.8, respectively, and 12 d of the 15-d P-value for the treatment by time interaction = 0.04. period recorded above 70 THI. In period 2 lasting 24 d, average THI was 71.9 ± 5.8 with a maximum THI was a treatment effect (P = 0.05, Table 2) for DMI. of 79.3 and a minimum of 59.4, 14 d of the 24 d above There were no differences amongst animals fed the 70 THI. Period 3 lasted for 23 d and had a maximum different treatments for back fat 12th rib on day 62 THI of 75.95 and a minimum of 62.7 with an average (P > 0.10) or LM area on day 62 (P = 0.15; Table 2). THI of 70.7 ± 3.7. Eight of 23 d were above 70 THI There was a treatment effect (P = 0.03) for blood (Figure 1). When blood samples were taken from the glucose concentration. Steers fed 0RPC had the animals, THI was different each time: for 1 d, THI greater overall blood glucose concentration than the was 73; for 15 d, THI 69; for 39 d, THI 66; and for 62 other two treatments (P  <  0.03; Table  3). There was d, THI 73. Despite no differences for THI, period 1 a treatment × day interaction (P  <  0.01; Table  3, had the greatest average THI, period 2 had the maxi- Figure  3) for plasma insulin concentration. Plasma mal THI and was the most variable (greater standard insulin concentration was similar on the steers fed the deviation), and period 3 had the least THI and was different treatments on days 0, 15, and 39, but it was the least variable. different on day 62, where the steers fed 1RPC had Temperature and humidity index averaged the greatest plasma insulin concentration (Figure  3). 72 ± 4.9, and according to Mader and Davis (2004), Plasma urea concentration also had a treatment × day animals experienced mild heat stress (THI between interaction (P = 0.02, Table 3). The main difference in 70 and 73.9) for 20 d and were heat-stressed (THI urea concentration was found on day 1. Plasma urea over 74)  for 22 of 62 d of the experiment. These concentration was different before the treatment sup- values confirm that at least for ¾ of the experiment, plementation started (P < 0.01, Table 3), but no differ- animals experienced some degree of heat stress. ences were found during the rest of the experiment. On Despite this, THI was not correlated with CPS. day 1 plasma urea concentration was greater (P < 0.05) Mader et  al. (2010) suggested that including wind for 0.5RPC (45.0 mg/dL) compared with 0RPC and speed and solar radiation increased the correlation 1RPC (34.7 and 29.1  mg/dL, respectively). Plasma between CPS and modified THI. This could have Translate basic science to industry innovation ADG, kg/d Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 6 Russi et al. Table 3. Effect of increasing dose of RPC on blood glucose concentration, plasma insulin, NEFA, and urea concentrations on finishing steers during heat stress Treatments (Trt) P-value Item 0RPC 0.5RPC 1RPC SEM Trt Day (d) Trt × d a b b Glucose, mg/dL 88 83 83 2.4 0.03 <0.01 0.35 Insulin, ng/mL 0.62 0.68 0.68 0.056 0.69 <0.01 0.01 NEFA, mM 184 191 161 17.2 0.42 <0.01 0.50 Urea, mg/dL 24 27 22 0.1 0.15 <0.01 0.02 1.4 Growth performance traits varied widely 1.2 between treatments from days 15 to 39. During this time, the steers had elevated average THI values and reported the greatest maximal THI from the whole 0.8 0RCP study (79.3). Also, 0.5RPC was the treatment that 0.6 0.5RPC showed the greatest ADG. This difference in growth 0.4 1RPC performance traits on this period could be partially 0.2 explained by the site of carbohydrate digestion and absorption which may have been modified by treatments. Even though treatments and diets were Days planned to be isoenergetic and isonitrogenous, dif- Figure  3. Effects of rumen-protected carbohydrate on plasma ferences in site of digestion and absorption of the insulin concentration in finishing steers during heat stress. Steers on protected carbohydrate were expected in the meta- treatment 0RPC received the basal diet plus 1  kg/d of supplement bolic utilization of the energy. top dressed (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts DM basis, without the ruminal protection). Steers on The experimental approach was to increase treatment 0.5RPC received the basal diet plus top dressed 0.5 kg/d of the amount of glucose reaching the small intes- supplement and 0.5  kg/d of RPC (58.1% soybean meal, 38.9% dex- tine using protected glucose instead of unpro- trose, 2% urea, and 1% minerals salts DM basis, with ruminal protec- tion). Steers on treatment 1RPC received the basal diet plus 1 kg/d of cessed grain. Energetically, it is clear that glucose RPC. Data are presented as least square means and SEM. P-value for is more efficiently used by the animal when it is the treatment by time interaction <0.01; *P  <  0.05 using the SLICE directly absorbed in the small intestine, rather than option of SAS. fermented in the rumen to VFA (Rodriguez et  al., explained the lack of correlation between CPS and 2004). When glucose reaches the small intestine, it THI in our study. It is also possible that the THI is fully absorbed, unlike what happens with starch was not great enough for the need of the animals to (Kreikemeier et al., 1991). Depending on the animal dissipate heat by increasing the CPS. model (dairy cow or finishing steer), there are limi- It is well documented that animals subjected to tations in the amount of starch that can be digested heat stress alter their eating behavior, which results in the small intestine (Branco et al., 1999). In grow- in a decrease of DMI and growth performance ing and finishing steers, approximately 700  g/d of (Mader, 2003). On periods of heat stress, cattle starch seems to be the limit for starch digestion in might benefit from the more energy dense diets, the small intestine (Huntington et  al., 2006). Any due to the depressed DMI. However, the increase excess of that amount would pass undigested con- in diet lipid concentration did not show that benefit tents to the lower gastrointestinal tract. This may (Gaughan and Mader, 2009). The inclusion of RPC be because of a decrease in α-amylase secretion by in our study had a time by treatment interaction for the pancreas (Walker and Harmon, 1995; Swanson growth performance, with an erratic pattern among et al, 2004). Although we did not measure glucose treatments. Our study also shows a dose increase absorption per se, unlike starch, glucose is read- in DMI. However, the increase on DMI was not ily absorbed in the small intestine with no limita- associated with changes on ADG or overall growth tions (Krehbiel et al., 1996; Rodriguez et al., 2004). performance. O’Brien et  al. (2010) showed that Using glucose as a source of energy appears to be changes in growth performance were associated a sound theory to enhance growth performance, with the decrease of DMI. However, our findings but no benefit has been found when abomasal glu- do not corroborate such association. Independently cose infusion was compared with other sources of of the DMI, steers fed 0.5RPC had a tendency to energy in growing steers (Schroeder et  al., 2006). have a greater ADG at the end of the experiment. Similarly, no benefits were observed on more milk Translate basic science to industry innovation Plasma Insulin, ng/mL Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 7 production when starch or glucose was infused to maximal dose of protected dextrose was 360 g and lactating dairy cows (Reynolds et al., 2001; Larsen there were no differences on the subcutaneous adi- and Kristensen, 2009). However, when the animal pose tissue accretion. Therefore, perhaps there is is metabolically challenged, glucose as a nutrient a need of a greater dose or time of supplementa- may have a chance to enhance performance, such tion of protected carbohydrate to obtain the same as observed in this current study during heat stress. response observed previously (Baldwin et al., 2007; From days 15 to 39, the animals experienced McLeod et  al., 2007). It is also possible that heat heat stress for the longest time. During this time, stress affected energy partitioning on a different feeding 0.5RPC had a greater ADG. It appears manner or the duration of the experiment was not that the use of glucose as a nutrient from RPC enough to see differences in BF or LM. may have benefited the animal. Despite the pos- Homoheretic mechanisms are irremediably itive response, it is unclear why dosing 180  g of challenged when animals are exposed to heat stress protected glucose (0.5RPC) vs. 360 g (1RPC) elic- and nutrients may not be all used for production. ited an improved growth. It is possible that the Blood and plasma metabolites are good descrip- combination of a portion of ruminally protected tors of this diversion (O’Brien et al., 2010). In this and unprotected glucose may have achieved a bal- experiment, blood glucose, insulin, and NEFA con- ance between enhanced ruminal fermentation and centration had different responses depending the small intestine digestion considering the responses sampling conditions such as THI, which described observed with 0.5RPC. Another explanation could a similar pattern observed in heated-stress dairy be that 1RPC with a greater dose of protected glu- cows (Wheelock et  al., 2010) and other species cose (360 g) triggered endocrine gut responses, such exposed to heat stress (Baumgard and Rhoads, as an increase in glucagon like peptide-1 or glu- 2012). Despite the decrease in DMI observed on cose-dependent insulinotropic polypeptide plasma 0RPC, and the fact that such treatment did not concentration (Relling and Reynolds, 2008). These have protected glucose, blood glucose concentra- peptides had been associated with DMI regulation tion was the greatest compared with the other two (Relling and Reynolds, 2007) and energy efficiency treatments. This response was not expected and is (Relling et al., 2014), respectively; however, the cur- not associated with changes in plasma insulin con- rent experiment was not designed to measure them. centration. Our current data do not allow us to find Differences in growth performance (BW and a physiological explanation, but it is possible that ADG) during the third period (from days 39 to the glucose–insulin metabolism could be changed 62)  were not observed in the experiment. The due to heat stress (Baumgard and Rhoads, 2012). decreased severity of THI recorded in the third It is also possible that the absorption of the glu- period may have allowed a compensatory growth, cose on the small intestine increased the secretion or may have created an effect of acclimatization of GLP-1 and GIP (Relling and Reynolds, 2008), of the animals to milder heat stress conditions which play a role in glucose metabolism. Therefore, (O’Brien et al., 2008). the increase of these two hormones facilitates the Besides the ability of RPC to enhance growth tissues to uptake the glucose, decreasing blood glu- performance in certain moments of the experiment, cose concentration. But more research needs to be we would have expected 0.5RPC to alter the pattern conducted to understand glucose metabolism when of tissue deposition, such as more intramuscular glucose is absorbed in the small intestine during fat, larger LM area, and less BF on day 62 of the heat stress periods in finishing cattle. Dosing RPC experiment (Smith and Crouse, 1984). This was not at the greatest dose (1RPC, 360 g of dextrose) reg- the case with these treatments, and a possible cause istered a peak in insulin decreasing glucose on day may be that heat stress altered physiological glucose 62. These data indicate that at least on the day of partitioning behavior in steer’s metabolism (O’Brien sampling, the dose of RPC was affecting blood et al., 2010; Rhoads et al., 2013). In McLeod et al. metabolite concentration. It is interesting to note (2007) and Baldwin et al. (2007) companion exper- that from the 3 d that blood was sampled, when the iments, infusion of up to 800  g/d of glucose into animals were already adapted to the diet (sampling the abomasum decreased DMI and resulted in on day 1 was taken before the adaptation period), greater adipose accretion, particularly the omen- day 62 was the day that reported the greatest THI tal depot–stimulating lipogenesis from glucose and (73.3). Therefore, on day 62, the animals were acetate is more pronounced in abdominal depots exposed to heat stress at the moment of sampling, relative to subcutaneous depots (Baldwin et  al., and this may be the reason we found greater insu- 2007; McLeod et al., 2007). In our experiment, the lin concentration for the treatment that had the full Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 8 Russi et al. Joy, F., J. J. McKinnon, S. Hendrick, P. Górka, and G. B. Penner. dose of rumen-protected carbohydrate (1RPC). It 2017. Effect of dietary energy substrate and days on feed is also possible that longer time on RPC supple- on apparent total tract digestibility, ruminal short-chain mentation changes the metabolic status of the ani- fatty acid absorption, acetate and glucose clearance, and mals for more insulin resistance (Joy et  al., 2017). insulin responsiveness in finishing feedlot cattle. J. Anim. For plasma urea concentration, we were expecting Sci. 95:5606–5616. doi:10.2527/jas2017.1817 Krehbiel, C. R., R. A. Britton, D. L. Harmon, J. P. Peters, R. a decrease due to RPC supplementation, associated A. Stock, and H. E. Grotjan. 1996. Effects of varying lev- with an increase in plasma insulin concentration els of duodenal or midjejunal glucose and 2-deoxyglucose (Reynolds and Maltby, 1994); however, we did not infusion on small intestinal disappearance and net por- find an association between plasma urean and insu- tal glucose flux in steers. J. Anim. Sci. 74:693–700. doi: lin concentration. https://doi.org/10.2527/1996.743693x In conclusion, the addition of RPC to the diet, Kreikemeier, K. K., D. L. Harmon, R. T. Brandt, Jr, T. B. Avery, and D. E.  Johnson. 1991. Small intestinal starch diges- animals change growth performance and plasma tion in steers: effect of various levels of abomasal glucose, metabolites in finishing feedlot steers during times corn starch and corn dextrin infusion on small intestinal with moderate THI. Despite a tendency for a better disappearance and net glucose absorption. J. Anim. Sci. growth in an intermediate dose that delivers 180 g/d 69:328–338. doi: https://doi.org/10.2527/1991.691328x of glucose to the small intestine, the results might Larsen, M., and N. B.  Kristensen. 2009. Effect of abomasal glucose infusion on splanchnic and whole-body glucose depend on the THI; however, more studies need to metabolism in periparturient dairy cows. J. Dairy Sci. be conducted to understand the role of RPC on 92:1071–1083. doi:10.3168/jds.2008-1453 growth and metabolism. Littell, R. C., G. A. Milliken, W. W. Stroup, R. D. Wolfinger, and O. Schabenberger. 2006. SAS for Mixed Models. 2nd LITERATURE CITED ed. SAS Institute, Cary, NC. Baldwin, R. L., 6th, K. R.  McLeod, J. P.  McNamara, T. Mader, T. L. 2003. Environmental stress in confined beef cat- H. Elsasser, and R. G. Baumann. 2007. Influence of abo- tle. J. Anim. 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Feeding rumen-inert E24. doi: https://doi.org/10.2527/2006.8413_supplE14x fats differing in their degree of saturation decreases intake Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 9 and increases plasma concentrations of gut peptides in activity and abundance in steers. J. Anim. Sci. 82:3015– lactating dairy cows. J Dairy Sci. 90:1506–1515. doi: http: 3023. doi:10.2527/2004.82103015x doi.org/10.3168/jds.s0022-0302(07)71636-3 Russi, J. P., P. F.  Russi, J. M.  Simondi, G. M.  Bonetto, Relling, A. E., and C. K. Reynolds. 2008. Abomasal infusion C.  Nasser Marzo, J. A.  Di Rienzo, and A. R.  Castillo. of casein, starch and soybean oil differentially affect 2011. 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Effects of heat stress and plane of or abomasal starch hydrolysate infusion on pancreatic nutrition on lactating holstein cows. I. Production, metab- exocrine secretion and blood glucose and insulin concen- olism, and aspects of circulating somatotropin. J. Dairy trations in steers. J. Anim. Sci. 73:3766–3774. https://doi. Sci. 92:1986–1997. doi:10.3168/jds.2008-1641 org/10.2527/1995.73123766x Rodriguez, S. M., K.  C. Guimaraes, J. C. Matthews, K. Wheelock, J. B., R. P. Rhoads, M. J. Vanbaale, S. R. Sanders, th R. McLeod, R. L. Baldwin, 4 , and D. L.  Harmon. and L. H. Baumgard. 2010. Effects of heat stress on ener- 2004. Influence of abomasal carbohydrates on small getic metabolism in lactating holstein cows. J. Dairy Sci. intestinal sodium-dependent glucose cotransporter 93:644–655. doi:10.3168/jds.2009-2295 Translate basic science to industry innovation http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Translational Animal Science Oxford University Press

Effects of rumen-protected carbohydrate supplementation on performance and blood metabolites in feedlot finishing steers during heat stress

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Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Effects of rumen-protected carbohydrate supplementation on performance and blood metabolites in feedlot finishing steers during heat stress † ‡ ||,1, Juan P. Russi, Nicolas DiLorenzo, and Alejandro E. Relling † ‡ RUPCA LLC, Merced, CA 95340; University of Florida, North Florida Research and Education Center, || Marianna, FL 32351; and Department of Animal Sciences, Ohio State University, Wooster, OH 44691 ABSTRACT: The objective of this experiment Mixed, SAS) using treatment, time, and their inter- was to evaluate the inclusion of a rumen-pro- action as a fixed variable and pen as a random var - tected carbohydrate (RPC) on growth perfor- iable. There were no differences (P > 0.10) between mance and blood metabolites of finishing steers the three treatments on CPS, BF, and LM area on during the summer. A 62-d feedlot study was con- day 62. There was a trend (P = 0.06) for treatment ducted using 135 Angus crossbred steers (body effect for a greater body weight on the 0.5RPC, and weight = 287 ± 13 kg). All animals were fed a basal a treatment effect for dry matter intake (P = 0.05). diet (BD), then treatments were top-dressed. The Treatment × day interactions were observed for treatments were the same composition and only var- average daily gain (ADG, P =0.04), suggesting a ied in ruminal degradability. Treatments were 1) a different response to treatments during the differ- BD with 1 kg/d of a control supplement (0RPC), ent sampling periods. There was a treatment effect 2) the BD plus 0.5 kg/d of the control supplement for blood glucose concentration (P = 0.03), having and 0.5 kg/d of RPC (0.5RCP), and 3) the BD with the 0RPC the greatest concentration. Treatment 1  kg/d of RPC supplement (1RPC). Temperature × day interactions were found for plasma insulin humidity index and cattle panting scores (CPS) concentration (P  =  0.01). The results suggest that were measured daily during the experiment. Growth the response to RPC supplementation depends in performance, back-fat over the 12th rib (BF), LM part on environment. The use of 0.5 kg/d of RPC area, blood glucose and plasma insulin, urea, and tends to improve overall body weight; however, the nonesterified fatty acid concentrations were meas- response to RPC on ADG and plasma insulin con- ured. Data were statistically analyzed (PROC centration depend on the time of sampling. Key words: blood metabolites, glucose, heat stress, protected carbohydrate © The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Transl. Anim. Sci. 2018.XX:XX–XX doi: 10.1093/tas/txy122 (ADG) (Mader et al., 2006). Several management INTRODUCTION strategies can be adopted to mitigate the effect of Maintaining an increased growth rate in feed- heat stress, such as the use of shades and sprin- lot steers during periods of heat stress can be chal- klers (Gaughan et  al., 2010). Altering feed deliv- lenging. Weather conditions can drastically affect ery patterns (Mader, 2003), or the amount of feed dry matter intake (DMI) and average daily gain delivered, or diet energy concentration can also be beneficial (Mader and Davis, 2004). Decreased DMI is not the only concern during Corresponding author: relling.1@osu.edu heat stress, but loss of production may also occur Received September 10, 2018. Accepted November 9, 2018. because the animal is metabolically challenged. 1 Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 2 Russi et al. For instance, in dairy cows only 30% to 50% of the procedures were approved by the Animal Care and reduction in milk production during heat stress can Use Committee from Veterinary College (Energy be explained by the diminished DMI (Rhoads et al., metabolism in beef cattle, 4 April 2011)  and La 2009). In growing bull calves exposed to heat stress, Plata National University. the decrease in growth performance can entirely be attributed to a decrease in DMI (O’Brien et al., Animals, Treatments, and Sampling 2010). Despite the different animal models, blood One hundred thirty-five (average body weight and plasma metabolite concentrations follow simi- [BW]  =  287  ±  13  kg) Angus crossbred steers were lar patterns. Even with the decrease in DMI during used in a 62-d experiment. Steers were blocked by heat stress, plasma glucose and nonesterified fatty BW and assigned to one of three treatments in a acids (NEFA) concentration are decreased and randomized complete block design with five pens insulin concentrations are increased (Baumgard per treatment. Steers were given ad libitum access to and Rhoads, 2012). the basal diet (BD). Treatment was top-dressed and Glucose concentration in blood had increased the treatments were as follows: 1) 1 kg/d of control by infusing starch or glucose into the abomasum supplement (0RPC), 2) 0.5 kg/d of control supple- (Kreikemeier et  al., 1991). Efficiency of conver - ment and 0.5 of kg/d RPC (0.5RPC), and 3) 1 kg/d sion of starch energy into tissue energy is improved of RPC (1RPC). The diets were formulated to when starch is digested in the small intestine rather meet or exceed requirements for beef (NRC, 2000). than fermented in the rumen (Harmon, 1992). Both the control supplement and RPC supplement But due to the rumen physiology, the use of a contained (% DM) the same ingredients (Table  1), rumen-unprotected glucose source is fermented in differing only in the processing of the carbohy- the rumen. Also there might be limitations in the drate. Rumen protection of RPC and its small amount of starch that the small intestine can digest intestine absorption had been tested and described (Branco et al., 1999). For example, in growing and on the patent of the product (U.S.  patent number finishing steers, Huntington et  al. (2006) showed 8,507,025). The target amount of protected dex- that approximately 700  g/d of starch seems to be trose for each treatment was 0, 180, or 360 g/d for the limit for starch digestion in the small intestine. 0RPC, 0.5RPC, and 1RPC, respectively (Table 1). Any excess of that amount would pass undigested Fifteen days before starting the experiment, contents to the lower gastrointestinal tract. This BW was recorded. Steers were stratified by BW may be because of a decrease in α-amylase secre- and used to establish the blocking weight criteria. tion by the pancreas (Walker and Harmon, 1995). Therefore, a rumen-protected glucose might be Table  1. Composition and chemical analysis (on beneficial. However, there are no studies that show DM basis) of basal diet and RPC or supplement the effect of protected glucose on feedlot perfor- mance on summer time condition. Ingredients Basal diet Suplement or RPC Based on the cited literature, we hypothesize Corn silage, % 16 – that feeding rumen-protected carbohydrates (RPCs) Dry-rolled corn, % 81 – will improve growth performance in heat-stressed Soybean meal, % – 58.1 animals. The objective of this study was to evalu- Dextrose, % – 38.9 Urea, % 0.55 2.8 ate the inclusion of a RPC on growth performance, Vitamins and minerals , % 2.25 – blood glucose, and plasma insulin and NEFA con- Mineral salts , % – 1.2 centration in finishing steers during summer. Diet DM,% 57.5 85.7 CP, % DM 10.1 27.8 MATERIALS AND METHODS ADF, % DM 14.9 14.4 NDF, % DM 31.7 28.8 Facilities EE, % DM 2.9 4.5 Ash, % DM 4.4 2.8 The experiment was conducted in a commer- The supplement and RPC differed only in the processing of the cial feedlot located in Buenos Aires, Argentina carbohydrate (i.e., protected or not from ruminal degradation). (lat.: 34°43′14″ S, long.: 63°05′08″ W), during the Minerals: Ca 27.74%, Mg 0.62%, Na 9.26%, Co 6.17  ppm, Cu summer of 2013–2014 (December, January, and 555 ppm, I 30.86 ppm, Mn 2037 ppm, Se 18.52 ppm, Zinc 2592 ppm, February). Fifteen soil-surfaced pens (12  ×  50 Monensin 1.03%. m) were used with nine steers in each pen. Water Mineral salts: Na bicarbonate 35  g, K HPO 6  g, KH PO 4.5  g, 2 4 2 4 ClNa 10 g. troughs were shared between two pens. All animal Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 3 Five blocks were assigned by weight, nine animals 1,000 × g to obtain plasma which was immediately per pen. frozen and stored at −20°C until analyzed for insu- Individual BW were scheduled to be obtained lin, NEFA, and urea. Whole blood glucose concen- on days 1, 15, 36, and 57. Day 15 was the end of trations were determined in situ with a glucometer the adaptation period and then every 21 d; how- (Optimum Xceedt, ABBOTT Lab Argentina). The ever, due to weather conditions (rainfall during the plasma insulin concentration was analyzed via radi- scheduled day), the actual BW was measured on oinmuno assay as described previously (Díaz-Torga days 1, 15, 39, and 62 relative to the starting day et  al., 2001). The minimum detectable concentra- (day 1). Animals were individually weighed before tion was 0.05 ng/mL. Intersample and intrasample the morning feeding. coefficients of variation were 8% and 7%, respec- Feed was offered daily and refusals were col- tively. Plasma NEFA concentration was analyzed lected once a week (days 8, 15, 23, 29, 33, 36, 44, 49, on days 0, 15, 39, and 62, using a colorimetric 54, 58, and 62) to determine DMI. The DMI obser- assay, following the protocol described by Randox vations on days 1 and 15 correspond to the adap- labs (FA 115 Randox Laboratories Ltd.). The min- tation period to the diet, and from day 16 onwards imum detectable concentration was 72  mM, and the steers were fully adapted to the final diet. the intrasample and intersample coefficients of Steers were adapted to the final diet during the variation were 7.5% and 23%, respectively. Plasma first 15 d of the experiment in three stages. The urea-N concentrations were analyzed on days 0, 39, first stage lasted for 5 d and the diet contained 60% and 62, using the colorimetric protocol described corn silage, 30% dry-rolled corn, 7.5% sunflower by Wiener Lab city (Rosario, Santa Fe, 2R UREA seed meal, 0.5 urea, and 2% of mineral and vitamin Color). The minimum detectable concentration mix with monensin (on DM bases). From days 6 to of urea was 2  mg/dL. Coefficients of variation of 11, the diet contained 53.5% corn silage, 43% dry- intrasamples and intersamples were 9.7% and 11%, rolled corn, 0.5% urea, and 2% of a mineral vita- respectively. min mix with monensin (on DM bases) and at this Temperature and humidity were recorded every stage, 0.5 kg of supplement or RPC was added as 30 min during the entire experiment by a meteoro- top-dress. From days 11 to 15, the diet contained logical station (Davies instruments, San Francisco, 37% corn silage, 60% dry-rolled corn, 0.6% urea, California) placed in the city of Piedritas 14 km and 2.4% of a mineral vitamin mix with monensin from the feed yard (Longitude 62°58′49″ W; lat- (on DM bases), 1 kg of supplement, RPC or half itude: 34°33′58″). Temperature humidity index and half was added as top-dress. From days 16 to (THI) was calculated according to Hubbard et  al. 62, end of the experiment, the animals were fed the (1999), using the following equation: THI = (0.8 × final diets as described in Table 1. temperature) + [(%  relative humidity/100) × (tem- Once in a week, individual feed ingredient perature − 14.4)] + 46.4. samples were taken and composite to be analyzed Daily average, maximum, and minimum THI for nutrient composition at the end of the experi- values were calculated for all the experimental peri- ment. Feed samples were analyzed for DM (60°C ods. Also, partial THI values were calculated for for 48  h), ADF and NDF (Ankom Technology the periods when the animals were weighed: period methods 5 and 6, respectively; Ankom Technology, 1 (days 1 to15), period 2 (days 16 to 39), and period Fairport, NY), CP (method 930.15; AOAC, 1996), 3 (days 40 to 62). ether extract (method 2; Ankom Technology, Cattle panting scores (CPS) were recorded from Fairport, NY), and total ash (600°C for 12 h). days 1 to 62, end of the experiment, between 1200 Back-fat at the 12th rib (BF) and LM area and 1600 h, as well as the time at which the obser- were measured by ultrasound on days 0 and 62 (Pie vation was taken. CPS were classified as described Medical mod. Aquila. Transductor 3.5 mhtz). by Mader et al. (2006) on a 0 to 4 scale with 0 being Blood samples were taken from the same four normal and 4 being severe open-mouthed panting animals, randomly selected at the start of the trial, accompanied by protruding tongue and excessive from each pen via jugular vein puncture before the salivation, usually with neck extended forward. For morning feeding. A drop of blood was used for glu- the correlation between CPS and THI, only days cose analysis and the rest of the blood was placed with a THI > 70 were taken into account, and this in tubes containing disodium EDTA (1.6  mg/mL included 29 of 62 d of the experiment. of blood) on days 0, 15, 39, and 62. Samples were Daily average THI measured was 72 ± 4.9 with maintained in a cooler until collection was finished. a maximal THI of 79 and a minimal THI of 59. Blood samples were then centrifuged for 20 min at Animals experienced THI over 70 for 46 d of the Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 4 Russi et al. THI THI 70 79.3 78.6 76.0 62.8 Avg. . THI: 71.9 Avg..THI: 70.7 Avg..THI: 72.9 60.9 Max THI: 79.3 Max THI: 76 Max THI: 78.6 59.5 Min THI: 59.4 Min THI: 62.8 Min THI: 60.8 Days <70THI: 10 de 24 Days <70THI: 8de 23 Days<70THI: 3 de15 Perriod1 Period 2Period 3 -2 26 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 Days Figure 1. THI across days on the experiment. Marked on the figure is the THI 70 and periods 1 to 3 organized to match sampling of perfor - mance and blood metabolites. 62-d experiment (Figure  1). When THI was sliced separate means when the time × treatment interac- into periods to match BW measurements (days 0 to tion was different (P < 0.10), and mean compari- sons were conducted using the PDIFF statement 15, 16 to 39, and 40 to 62), no statistical differences of SAS whenever there was only a main effect or a were observed on average THI amongst the three treatment effect for a particular day after the use of periods (P = 0.40). the SLICE option. The PROC Corr of SAS, version 9.4 (SAS Statistical Analysis Institute, Inc., Cary, NC), was used to evaluate cor- relation between THI and CPS and CPS and time Data were analyzed as a randomized complete of the day when the observation was reported. block design with repeated measurements, using the MIXED procedure of SAS, version 9.4 (SAS RESULTS Institute, Inc., Cary, NC). The model included the fixed effect of treatments, days (time), and interac- There was no correlation between THI and CPS tions between treatments and days, and the random (r = 0.18, P = 0.35) during the experiment. Despite the effect of pen and block (BW). Days was consid- lack of correlation between THI and CPS, CPS was ered as the repeated statement. Pen was consid- above 1 (on every steer) on the 29 d where THI was ered as the experimental unit. Block was removed greater than 70. from the model when it was not significant (P > No treatment × day interaction were observed 0.1). The covariance structures compared included for BW, but animals fed 0.5RPC and 1RPC had compound symmetry, unstructured, spatial power, a tendency for treatment effect (P  =  0.06) to have autoregressive, and heterogeneous autoregressive. a greater BW than 0RPC (Table  2). There was a Dependent variables were analyzed using the covar- treatment × day interaction (P  =  0.04, Figure  2) iance-structured spatial power, because it gave the for ADG. In period 2, steers fed 0.5RPC reported best fit based on the Akaike information criterion the largest ADG of 1.42 kg/d followed by the steers (Littell et al., 2006). Back fat thickness at the 12th fed 1RPC with 1.23 kg/d and the steers fed 0RPC rib and LM area on day 62 did not have repeated 1.13 kg/d, but there were no differences at the end measurements, and the initial value on day 1 was of the experiment on the total ADG comparing the used as a co-variate. The slice option was used to animals fed the three treatments (Figure  2). There Translate basic science to industry innovation THI Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 5 Table 2. Effect of increasing dose of RPC on DMI, BW, back fat (BF) at 12th rib on 63 d and Longissimus muscle (LM) area on day 62 in finishing steers during heat stress. Treatment (Trt) P-value Item 0RPC 0.5RPC 1RPC SEM Trt Day (d) Trt × d Initial BW, kg 281 285 284 1.6 0.06 <0.01 0.76 Final BW, kg 350 355 352 a ab b DMI, kg/d 9.8 9.9 10.1 0.07 0.05 <0.01 0.14 BF, cm 0.59 0.6 0.6 0.015 0.82 – – LM on day 62, cm 57.39 54.56 56.56 0.967 0.15 – – NEFA concentration was not different amongst the 1.6 steers fed the different treatments (P = 0.15, Table 3). 1.4 1.2 DISCUSSION 0RCP 0.8 Diets were designed to be isoenergetic and 0.6 0.5RPC isonitrogenous. All treatments received the same 0.4 1RPC amount of dextrose (360 g) and the difference was 0.2 in the ruminal protection of the carbohydrate. In 0RPC, none of the 360  g of dextrose were pro- 15 39 62 tected from ruminal degradation and all of the sol- Days uble carbohydrates were assumed to fuel microbial Figure  2. Effects of increasing dose of RPC on ADG in finishing growth in the rumen. In 0.5RPC, only 180 g of dex- steers during heat stress. The dotted line represents the daily THI. 0RPC steers received the basal diet plus 1  kg/d of supplement top dressed trose were protected and 180  g were unprotected, (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts and cattle fed 1RPC received 360 g of rumen-pro- DM basis, without the ruminal protection). 0.5RPC steers received the tected dextrose (Russi et al., 2011). basal diet plus top dressed 0.5 kg/d of supplement and 0.5 kg/d of RPC Period 1 lasted for 15 d and had an average THI (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts DM basis, with ruminal protection). 1RPC steers received the basal diet of 72.9  ±  5 with a maximum and minimum THI plus 1 kg/d of RPC. Data are presented as least square means and SEM. of 78.6 and 60.8, respectively, and 12 d of the 15-d P-value for the treatment by time interaction = 0.04. period recorded above 70 THI. In period 2 lasting 24 d, average THI was 71.9 ± 5.8 with a maximum THI was a treatment effect (P = 0.05, Table 2) for DMI. of 79.3 and a minimum of 59.4, 14 d of the 24 d above There were no differences amongst animals fed the 70 THI. Period 3 lasted for 23 d and had a maximum different treatments for back fat 12th rib on day 62 THI of 75.95 and a minimum of 62.7 with an average (P > 0.10) or LM area on day 62 (P = 0.15; Table 2). THI of 70.7 ± 3.7. Eight of 23 d were above 70 THI There was a treatment effect (P = 0.03) for blood (Figure 1). When blood samples were taken from the glucose concentration. Steers fed 0RPC had the animals, THI was different each time: for 1 d, THI greater overall blood glucose concentration than the was 73; for 15 d, THI 69; for 39 d, THI 66; and for 62 other two treatments (P  <  0.03; Table  3). There was d, THI 73. Despite no differences for THI, period 1 a treatment × day interaction (P  <  0.01; Table  3, had the greatest average THI, period 2 had the maxi- Figure  3) for plasma insulin concentration. Plasma mal THI and was the most variable (greater standard insulin concentration was similar on the steers fed the deviation), and period 3 had the least THI and was different treatments on days 0, 15, and 39, but it was the least variable. different on day 62, where the steers fed 1RPC had Temperature and humidity index averaged the greatest plasma insulin concentration (Figure  3). 72 ± 4.9, and according to Mader and Davis (2004), Plasma urea concentration also had a treatment × day animals experienced mild heat stress (THI between interaction (P = 0.02, Table 3). The main difference in 70 and 73.9) for 20 d and were heat-stressed (THI urea concentration was found on day 1. Plasma urea over 74)  for 22 of 62 d of the experiment. These concentration was different before the treatment sup- values confirm that at least for ¾ of the experiment, plementation started (P < 0.01, Table 3), but no differ- animals experienced some degree of heat stress. ences were found during the rest of the experiment. On Despite this, THI was not correlated with CPS. day 1 plasma urea concentration was greater (P < 0.05) Mader et  al. (2010) suggested that including wind for 0.5RPC (45.0 mg/dL) compared with 0RPC and speed and solar radiation increased the correlation 1RPC (34.7 and 29.1  mg/dL, respectively). Plasma between CPS and modified THI. This could have Translate basic science to industry innovation ADG, kg/d Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 6 Russi et al. Table 3. Effect of increasing dose of RPC on blood glucose concentration, plasma insulin, NEFA, and urea concentrations on finishing steers during heat stress Treatments (Trt) P-value Item 0RPC 0.5RPC 1RPC SEM Trt Day (d) Trt × d a b b Glucose, mg/dL 88 83 83 2.4 0.03 <0.01 0.35 Insulin, ng/mL 0.62 0.68 0.68 0.056 0.69 <0.01 0.01 NEFA, mM 184 191 161 17.2 0.42 <0.01 0.50 Urea, mg/dL 24 27 22 0.1 0.15 <0.01 0.02 1.4 Growth performance traits varied widely 1.2 between treatments from days 15 to 39. During this time, the steers had elevated average THI values and reported the greatest maximal THI from the whole 0.8 0RCP study (79.3). Also, 0.5RPC was the treatment that 0.6 0.5RPC showed the greatest ADG. This difference in growth 0.4 1RPC performance traits on this period could be partially 0.2 explained by the site of carbohydrate digestion and absorption which may have been modified by treatments. Even though treatments and diets were Days planned to be isoenergetic and isonitrogenous, dif- Figure  3. Effects of rumen-protected carbohydrate on plasma ferences in site of digestion and absorption of the insulin concentration in finishing steers during heat stress. Steers on protected carbohydrate were expected in the meta- treatment 0RPC received the basal diet plus 1  kg/d of supplement bolic utilization of the energy. top dressed (58.1% soybean meal, 38.9% dextrose, 2% urea, and 1% minerals salts DM basis, without the ruminal protection). Steers on The experimental approach was to increase treatment 0.5RPC received the basal diet plus top dressed 0.5 kg/d of the amount of glucose reaching the small intes- supplement and 0.5  kg/d of RPC (58.1% soybean meal, 38.9% dex- tine using protected glucose instead of unpro- trose, 2% urea, and 1% minerals salts DM basis, with ruminal protec- tion). Steers on treatment 1RPC received the basal diet plus 1 kg/d of cessed grain. Energetically, it is clear that glucose RPC. Data are presented as least square means and SEM. P-value for is more efficiently used by the animal when it is the treatment by time interaction <0.01; *P  <  0.05 using the SLICE directly absorbed in the small intestine, rather than option of SAS. fermented in the rumen to VFA (Rodriguez et  al., explained the lack of correlation between CPS and 2004). When glucose reaches the small intestine, it THI in our study. It is also possible that the THI is fully absorbed, unlike what happens with starch was not great enough for the need of the animals to (Kreikemeier et al., 1991). Depending on the animal dissipate heat by increasing the CPS. model (dairy cow or finishing steer), there are limi- It is well documented that animals subjected to tations in the amount of starch that can be digested heat stress alter their eating behavior, which results in the small intestine (Branco et al., 1999). In grow- in a decrease of DMI and growth performance ing and finishing steers, approximately 700  g/d of (Mader, 2003). On periods of heat stress, cattle starch seems to be the limit for starch digestion in might benefit from the more energy dense diets, the small intestine (Huntington et  al., 2006). Any due to the depressed DMI. However, the increase excess of that amount would pass undigested con- in diet lipid concentration did not show that benefit tents to the lower gastrointestinal tract. This may (Gaughan and Mader, 2009). The inclusion of RPC be because of a decrease in α-amylase secretion by in our study had a time by treatment interaction for the pancreas (Walker and Harmon, 1995; Swanson growth performance, with an erratic pattern among et al, 2004). Although we did not measure glucose treatments. Our study also shows a dose increase absorption per se, unlike starch, glucose is read- in DMI. However, the increase on DMI was not ily absorbed in the small intestine with no limita- associated with changes on ADG or overall growth tions (Krehbiel et al., 1996; Rodriguez et al., 2004). performance. O’Brien et  al. (2010) showed that Using glucose as a source of energy appears to be changes in growth performance were associated a sound theory to enhance growth performance, with the decrease of DMI. However, our findings but no benefit has been found when abomasal glu- do not corroborate such association. Independently cose infusion was compared with other sources of of the DMI, steers fed 0.5RPC had a tendency to energy in growing steers (Schroeder et  al., 2006). have a greater ADG at the end of the experiment. Similarly, no benefits were observed on more milk Translate basic science to industry innovation Plasma Insulin, ng/mL Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 Rumen bypass carbohydrate in feedlot steers 7 production when starch or glucose was infused to maximal dose of protected dextrose was 360 g and lactating dairy cows (Reynolds et al., 2001; Larsen there were no differences on the subcutaneous adi- and Kristensen, 2009). However, when the animal pose tissue accretion. Therefore, perhaps there is is metabolically challenged, glucose as a nutrient a need of a greater dose or time of supplementa- may have a chance to enhance performance, such tion of protected carbohydrate to obtain the same as observed in this current study during heat stress. response observed previously (Baldwin et al., 2007; From days 15 to 39, the animals experienced McLeod et  al., 2007). It is also possible that heat heat stress for the longest time. During this time, stress affected energy partitioning on a different feeding 0.5RPC had a greater ADG. It appears manner or the duration of the experiment was not that the use of glucose as a nutrient from RPC enough to see differences in BF or LM. may have benefited the animal. Despite the pos- Homoheretic mechanisms are irremediably itive response, it is unclear why dosing 180  g of challenged when animals are exposed to heat stress protected glucose (0.5RPC) vs. 360 g (1RPC) elic- and nutrients may not be all used for production. ited an improved growth. It is possible that the Blood and plasma metabolites are good descrip- combination of a portion of ruminally protected tors of this diversion (O’Brien et al., 2010). In this and unprotected glucose may have achieved a bal- experiment, blood glucose, insulin, and NEFA con- ance between enhanced ruminal fermentation and centration had different responses depending the small intestine digestion considering the responses sampling conditions such as THI, which described observed with 0.5RPC. Another explanation could a similar pattern observed in heated-stress dairy be that 1RPC with a greater dose of protected glu- cows (Wheelock et  al., 2010) and other species cose (360 g) triggered endocrine gut responses, such exposed to heat stress (Baumgard and Rhoads, as an increase in glucagon like peptide-1 or glu- 2012). Despite the decrease in DMI observed on cose-dependent insulinotropic polypeptide plasma 0RPC, and the fact that such treatment did not concentration (Relling and Reynolds, 2008). These have protected glucose, blood glucose concentra- peptides had been associated with DMI regulation tion was the greatest compared with the other two (Relling and Reynolds, 2007) and energy efficiency treatments. This response was not expected and is (Relling et al., 2014), respectively; however, the cur- not associated with changes in plasma insulin con- rent experiment was not designed to measure them. centration. Our current data do not allow us to find Differences in growth performance (BW and a physiological explanation, but it is possible that ADG) during the third period (from days 39 to the glucose–insulin metabolism could be changed 62)  were not observed in the experiment. The due to heat stress (Baumgard and Rhoads, 2012). decreased severity of THI recorded in the third It is also possible that the absorption of the glu- period may have allowed a compensatory growth, cose on the small intestine increased the secretion or may have created an effect of acclimatization of GLP-1 and GIP (Relling and Reynolds, 2008), of the animals to milder heat stress conditions which play a role in glucose metabolism. Therefore, (O’Brien et al., 2008). the increase of these two hormones facilitates the Besides the ability of RPC to enhance growth tissues to uptake the glucose, decreasing blood glu- performance in certain moments of the experiment, cose concentration. But more research needs to be we would have expected 0.5RPC to alter the pattern conducted to understand glucose metabolism when of tissue deposition, such as more intramuscular glucose is absorbed in the small intestine during fat, larger LM area, and less BF on day 62 of the heat stress periods in finishing cattle. Dosing RPC experiment (Smith and Crouse, 1984). This was not at the greatest dose (1RPC, 360 g of dextrose) reg- the case with these treatments, and a possible cause istered a peak in insulin decreasing glucose on day may be that heat stress altered physiological glucose 62. These data indicate that at least on the day of partitioning behavior in steer’s metabolism (O’Brien sampling, the dose of RPC was affecting blood et al., 2010; Rhoads et al., 2013). In McLeod et al. metabolite concentration. It is interesting to note (2007) and Baldwin et al. (2007) companion exper- that from the 3 d that blood was sampled, when the iments, infusion of up to 800  g/d of glucose into animals were already adapted to the diet (sampling the abomasum decreased DMI and resulted in on day 1 was taken before the adaptation period), greater adipose accretion, particularly the omen- day 62 was the day that reported the greatest THI tal depot–stimulating lipogenesis from glucose and (73.3). Therefore, on day 62, the animals were acetate is more pronounced in abdominal depots exposed to heat stress at the moment of sampling, relative to subcutaneous depots (Baldwin et  al., and this may be the reason we found greater insu- 2007; McLeod et al., 2007). In our experiment, the lin concentration for the treatment that had the full Translate basic science to industry innovation Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txy122/5197930 by Ed 'DeepDyve' Gillespie user on 27 November 2018 8 Russi et al. Joy, F., J. J. McKinnon, S. Hendrick, P. Górka, and G. B. Penner. dose of rumen-protected carbohydrate (1RPC). It 2017. Effect of dietary energy substrate and days on feed is also possible that longer time on RPC supple- on apparent total tract digestibility, ruminal short-chain mentation changes the metabolic status of the ani- fatty acid absorption, acetate and glucose clearance, and mals for more insulin resistance (Joy et  al., 2017). insulin responsiveness in finishing feedlot cattle. J. Anim. For plasma urea concentration, we were expecting Sci. 95:5606–5616. doi:10.2527/jas2017.1817 Krehbiel, C. R., R. A. Britton, D. L. Harmon, J. P. Peters, R. a decrease due to RPC supplementation, associated A. Stock, and H. E. Grotjan. 1996. Effects of varying lev- with an increase in plasma insulin concentration els of duodenal or midjejunal glucose and 2-deoxyglucose (Reynolds and Maltby, 1994); however, we did not infusion on small intestinal disappearance and net por- find an association between plasma urean and insu- tal glucose flux in steers. J. Anim. Sci. 74:693–700. doi: lin concentration. https://doi.org/10.2527/1996.743693x In conclusion, the addition of RPC to the diet, Kreikemeier, K. K., D. L. Harmon, R. T. Brandt, Jr, T. B. Avery, and D. E.  Johnson. 1991. Small intestinal starch diges- animals change growth performance and plasma tion in steers: effect of various levels of abomasal glucose, metabolites in finishing feedlot steers during times corn starch and corn dextrin infusion on small intestinal with moderate THI. Despite a tendency for a better disappearance and net glucose absorption. J. Anim. 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Translational Animal ScienceOxford University Press

Published: Nov 22, 2018

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