PSXIII-29 Late-Breaking: Relationships between feed efficiency traits, gas emissions, and calculated heat production and respiratory quotients in mature beef cows

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 378-379
Author(s):  
Lauren Finlay ◽  
Katharine M Wood
Keyword(s):  
Gas Exchange ◽  
Heat Production ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Beef Cows ◽  
Gas Production ◽  
Feed Ratio ◽  
Metabolic Efficiency ◽  
O2 Consumption ◽  
Pearson Correlations

Abstract This research evaluated relationships between feed efficiency measurements including residual feed intake (RFI), gain to feed ratio (G:F) and enteric gas production of methane (CH4), carbon dioxide (CO2), oxygen, (O2) along with calculated respiratory quotient (RQ) and heat production (HP) of mature beef cows. Sixty pregnant multiparous Angus beef cows were measured for individual intake for 10 weeks leading up to parturition. Cows were individually fed using the Insentec feeding system to measure individual feed intake. Pens of cows were rotated weekly to the C-Lock Greenfeed trailer (C-Lock Inc.) to measure gas production for a minimum 2 periods per group. Cows were weighed, body condition scored, and ultrasound performed for rib and rump fat depth every 28 days and calf birth weight was recorded. Pearson correlations were conducted to determine relationships between gas exchange measurements and feed efficiency measures. The model for RFI included ADG, pregnancy corrected BW, and ultrasound measures of rib and rump fat (R2= 0.32). Methane emissions were 263±40.3 g CH4/d in dry lot, and daily enteric CH4 emissions per kg of pregnancy corrected body weight ranging from 0.26 to 0.53 g CH4/kg pcBW. Pearson correlations found positive correlations between DMI and CH4 and CO2 (P ≤ 0.001). Pregnancy corrected BW was also positively correlated with total O2 consumption and calculated HP (P ≤ 0.001) and negatively correlated with RQ (P = 0.04). However, RFI and feed conversion ratio were not significantly correlated with gas measurements, or calculated HP or RQ (P ≥ 0.1), although DMI/kg of BW tended (P = 0.098) to be negatively correlated with O2 consumption. In conclusion, accurately identifying feed efficiency in mature beef cows continues to be a challenge. However, the inclusion of gas exchange measures and calorimetry measurements may be able to better assess metabolic efficiency in mature beef cattle.

Genetic parameters for feed intake and efficiency in lactating beef cows

1996 ◽  
Vol 76 (1) ◽  
pp. 81-87 ◽  
Author(s):  
L. Q. Fan ◽  
J. W. Wilton ◽  
P. E. Colucci
Keyword(s):  
Milk Yield ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
National Research Council ◽  
Beef Cows ◽  
Feed Consumption ◽  
Research Centre ◽  
Total Data

Genetic parameters of feed intake and efficiency and production traits for lactating beef cows were estimated from data collected from 1980 to 1988 at the Elora Beef Research Centre, Guelph, Ontario. Estimates were obtained using restricted maximum likelihood (REML) with an individual animal model with year–season–treatment, sex of calf, parity, breeding system, covariate daily change of backfat depth and direct genetic and permanent environmental effects. The data included 1174 observations, 511 cows, 369 dam–maternal grand dam pairs and 245 sires of cows. Feed efficiency for milk was calculated as milk yield relative to energy consumed for milk and maintenance and residual feed consumption as estimated energy intake minus energy requirements as estimated by the National Research Council. Heritabilities for Herefords alone and total data, respectively, were estimated to be 0.02 and 0.11 for cow's daily ME intake (MEI), 0.26 and 0.26 for daily milk yield (DMY), 0.45 and 0.33 for milk fat percentage (MFP), 0.29 and 0.40 for metabolic body weight (MBW), 0.21 and 0.10 for calf weaning weight as a proportion of cow weight at weaning (PPW), 0.18 and 0.11 for feed efficiency for milk (FE), and 0.23 and 0.03 for residual feed consumption (RFC). Genetic correlations of output (DMY) and input (MEI) were 0.31 for Hereford and 0.75 for the total data. Genetic correlations of RFC with both output (DMY) and input (MEI) were low. Genetically, PPW was positively associated with FE and DMY and negatively associated with MBW. Key words: Genetic parameters, feed efficiency, lactation, beef cow

scholarly journals Relationships between feed efficiency and puberty in Bos taurus and Bos indicus-influenced replacement beef heifers

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Luara B Canal ◽  
Pedro L P Fontes ◽  
Carla D Sanford ◽  
Vitor R G Mercadante ◽  
Nicolas DiLorenzo ◽  
...  
Keyword(s):  
Breeding Season ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Bos Taurus ◽  
Average Daily Gain ◽  
Bos Indicus ◽  
Residual Feed Intake ◽  
Feed Ratio ◽  
Beef Heifers ◽  
Efficiency Test

Abstract The objective of this experiment was to investigate the relationship between residual feed intake (RFI) and parameters associated with reproductive efficiency in growing beef heifers. One hundred and seventy-nine replacement beef heifers (Bos taurus and Bos indicus-influenced) were enrolled in a retrospective cohort design. Heifers were assigned to a 70-d feed efficiency test, and results were utilized to retrospectively classify heifers into low (n = 51), medium (n = 66), or high (n = 62) RFI groups based on their individual RFI values. Blood samples were collected weekly throughout the feed efficiency test and breeding season, which were analyzed for plasma concentration of progesterone to determine age at puberty (PUB). By design, residual feed intake differed among RFI groups where high (1.21 ± 0.08 kg/d) had greater (P < 0.01) RFI than medium (0.00 ± 0.08 kg/d) and low RFI groups (–1.49 ± 0.09 kg/d), and medium had greater (P < 0.01) RFI than low RFI heifers. Yet, no differences were observed between breed types for RFI (P = 0.53). Average daily gain (ADG) differed between breed types where Bos taurus heifers had greater ADG (P = 0.02) than B. indicus-influenced heifers. Furthermore, ADG tended (P = 0.08) to differ among RFI groups, where medium RFI heifers tended to have reduced ADG compared with low and high RFI heifers. No differences were determined between breed types for gain-to-feed ratio (G:F; P = 0.20; however, G:F differed among RFI groups and was greater (P < 0.01) in low vs. high, and low vs. medium RFI heifers. The percentage of cycling heifers by the start of the breeding season differed (P = 0.03) by RFI group, where a greater percentage of low RFI heifers were cycling compared with high RFI heifers. A difference was determined on PUB between breed types (P = 0.03), where Bos taurus (393.40 ± 4.64 d) heifers had a reduced PUB compared with B. indicus-influenced (406.90 ± 5.07 d) heifers. In addition, PUB differed by RFI group where low (385.96 ± 6.20 d; P < 0.01) and medium (398.47 ± 5.47 d; P = 0.02) RFI heifers had a reduced PUB compared with High RFI heifers (416.03 ± 5.58 d). In conclusion, more feed efficient heifers attained PUB earlier than less feed efficient heifers. Therefore, selection of heifers for feed efficiency may positively impact reproductive performance of replacement beef heifers.

scholarly journals Effects of timing of weaning on energy utilization in primiparous beef cows and post-weaning performance of their progeny1

2019 ◽  
Vol 97 (3) ◽  
pp. 1198-1211 ◽  
Author(s):  
Aksel Wiseman ◽  
Miles Redden ◽  
Adam McGee ◽  
Courtney Spencer ◽  
Ryan Reuter ◽  
...  
Keyword(s):  
Body Weight ◽  
Feed Intake ◽  
Beef Cows ◽  
Feed Consumption ◽  
Energy Requirements ◽  
Feed Ratio ◽  
Biological Efficiency ◽  
Maintenance Energy ◽  
Early Weaning ◽  
Calf Performance

Abstract Early weaning is used to minimize cow nutrient requirements in situations where feed inputs are scarce or expensive. For many years, maintenance energy requirements have been assumed to be 20% greater in lactating compared with non-lactating beef cows. While not well established, maintenance energy requirements are thought to be greatest in primiparous cows and to decline with age. Consequently, early weaning primiparous cow–calf pairs should improve overall efficiency, particularly in situations where mid-to-late lactation forage or feed nutritive value is low. The objective of this study was to determine the biological efficiency of early weaning and maintenance energy requirements of lactating versus non-lactating primiparous cows. Experiments were conducted in two consecutive years using 90 primiparous cows and their calves (48 in yr 1, 42 in yr 2). Pairs were randomly assigned to one of the six pens (8 pairs/pen yr 1, 7 pairs/pen yr 2) and pens were randomly assigned to 1 of 2 treatments; (1) early weaning (130 d ± 15.4; EW, n = 6) and (2) traditional weaning (226 d ± 13.1; TW, n = 6). Late lactation cow and calf performance and feed consumption were measured for 92 d (yr 1) and 100 d (yr 2). Cows were limit-fed to meet maintenance requirements, while calves were offered ad libitum access to the same diet in a creep-feeding area. Calves were not allowed access to the cows’ feed. Cow feed intake, body condition score, body weight (BW), milk yield and composition, and calf body weight gain and creep feed intake were recorded. After accounting for lactation and retained energy, there was a trend for greater maintenance energy requirements of lactating primiparous cows (P = 0.07). From the early weaning date to traditional weaning date, calf average daily gain (ADG) was greater (P < 0.01) for TW calves. Feed and energy efficiency of the pair was improved for the TW system (P < 0.01). Greater ADG were reported for EW calves during the stocker period (P = 0.03), but there were no differences during the finishing period (P > 0.40). At harvest, BW was greater (P = 0.02) and gain to feed ratio tended (P = 0.06) to be improved for TW calves. The increased TW calf performance offset the additional maintenance costs of their lactating dams, resulting in the TW system converting total feed energy to kilograms of calf BW gain more efficiently.

Relationship between behavioural reactivity and feed efficiency in housed sheep

2010 ◽  
Vol 50 (7) ◽  
pp. 683 ◽  
Author(s):  
C. Amdi ◽  
A. R. Williams ◽  
S. K. Maloney ◽  
A. H. Tauson ◽  
S. A. Knott ◽  
...  
Keyword(s):  
Weight Gain ◽  
Body Condition ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Body Condition Score ◽  
Daily Weight Gain ◽  
Metabolic Efficiency ◽  
Average Daily Weight Gain ◽  
Condition Score ◽  
Animal House

In this study we test the hypothesis that selecting sheep for a low behavioural reactivity to stressful situations will improve their metabolic efficiency, and thereby feed efficiency, during a controlled trial in an animal house. Twenty-four Merino wethers were used, 12 each from lines selected for high (HBR) and low (LBR) behavioural reactivity to stressful stimuli (human presence and social isolation). The sheep were habituated to the experimental procedures for 10 days, followed by 45 days during which voluntary feed intake was measured so that total daily energy intake was quantified. The sheep were weighed twice weekly before daily feeding. Feed efficiency was determined by measuring net feed intake, average daily weight gain and body condition score. Our hypothesis was not supported by the results of this study. There was no difference between LBR and HBR sheep in average daily weight gain or body condition score. The net feed intake of HBR sheep was lower than that of LBR sheep (P = 0.02), indicating that under the conditions of our experiment, HBR sheep were actually more feed efficient than LBR sheep. This study was carried out on sheep with steady intakes and in familiar surroundings. It is possible that LBR sheep may be more efficient than HBR sheep in more stressful situations.

scholarly journals 76 Effects of replacing monensin and tylosin in finishing cattle diets with essential oils and/or benzoic acid on growth performance and carcass characteristics

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 42-43
Author(s):  
Lydia M Wang ◽  
Ira B Mandell ◽  
Benjamin M Bohrer
Keyword(s):  
Benzoic Acid ◽  
Essential Oils ◽  
Growth Performance ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Carcass Characteristics ◽  
Feed Ratio ◽  
Finishing Cattle ◽  
Quality Grade ◽  
Dietary Treatments

Abstract This study examined the effects of replacing monensin and tylosin with essential oils and/or benzoic acid in finishing cattle diets on growth performance, feed efficiency, and carcass characteristics. Crossbred steers (n = 68; BW = 539 ± 4 kg) were blocked by starting weight into three blocks and were assigned to 1 of 5 finishing diets: no additional supplement (CON), monensin/tylosin (M/T), essential oils (EO), benzoic acid (BA), or a combination of essential oils and benzoic acid (COMBO). Steers were housed with two dietary treatments represented in seven pens, while an eighth pen only housed steers fed the CON diet. Individual animal feed intake was collected using an Insentec feeding system, so steer was the experimental unit for all analyses. Data were analyzed using a randomized complete block design with fixed effect of treatment and random effect of block. Final weight, average daily gain, and dry matter intake were similar (P > 0.12) among treatments. Gain to feed ratio differed (P = 0.05) among treatments, specifically steers fed the M/T diet had greater G:F compared with steers fed CON, EO, and COMBO diets. For carcass characteristics, there were no significant treatment differences in hot carcass weight (P = 0.19), dressing percentage (P = 0.62), ribeye area (P = 0.49), fat thickness (P = 0.84), calculated yield grade (P = 0.91), marbling score (P = 0.07), and yield grade (P = 0.43). Quality grade differed (P = 0.05) among treatments, with steers fed the EO diet having a lower quality grade than all other dietary treatments. Overall, steers supplemented with essential oils and(or) benzoic acid had similar gain, feed intake, and carcass parameters as steers fed CON, while steers fed M/T had slightly improved feed efficiency compared to all other treatments.

scholarly journals Genetic parameters for feed intake and efficiency in dry pregnant beef cows

1996 ◽  
Vol 76 (1) ◽  
pp. 73-79 ◽  
Author(s):  
L. Q. Fan ◽  
J. W. Wilton ◽  
P. E. Colucci
Keyword(s):  
Energy Intake ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Average Daily Gain ◽  
Beef Cows ◽  
Feed Consumption ◽  
Research Centre ◽  
Total Data

Genetic parameters of feed efficiency and traits relative to feed efficiency for dry pregnant beef cows were estimated from data collected from 1980 to 1988 at the Elora Beef Research Centre, Guelph, Ontario. Measurements of individual feed intake were available for 90 d immediately before calving. Estimates of parameters were obtained using derivative-free restricted maximum likelihood (DFREML), with an individual-animal model with year-season, sex of fetus, parity breeding system, covariate daily backfat change, and genetic and permanent environmental effects. The data included 729 observations, 337 cows, 278 dam–maternal grand dam pairs, and 208 sires of cows. Feed efficiency for pre-calving gain of fetus was calculated as pre-calving gain relative to energy consumed for maintenance and pregnancy, with adjustment of intake for weight change by National Research Council (NRC) standards (FE) or by regression analysis (FER). Residual feed consumption was calculated as energy intake minus energy requirements, with requirements estimated by NRC standards (RFC) or by regression (RFCR). Heritabilities for Hereford alone and total data, respectively, were 0.03 and 0.16 for daily metabolizable energy intake (MEI); 0.20 and 0.44 for metabolic body weight (MBW); 0.28 and 0.22 for fetal pre-calving average daily gain (PADG); 0.11 and 0.05 for FE; 0.28 and 0.20 for FER; 0.01 and 0.04 for RFC; and 0.03 and 0.22 for RFCR. Genetic and phenotypic correlations indicated a positive association of energy intake with pre-calving fetal gain and weight of cow, although correlations with weight of cow were low. Residual feed consumption for the total data was not genetically associated with MEI or PADG, moderately associated with MBW, and highly negatively associated with FE. Key words: Genetic parameter, feed efficiency, pregnancy, beef

scholarly journals RAPID COMMUNICATION: Residual feed intake in beef cattle is associated with differences in protein turnover and nutrient transporters in ruminal epithelium

2019 ◽  
Vol 97 (5) ◽  
pp. 2181-2187
Author(s):  
Ahmed A Elolimy ◽  
Emad Abdel-Hamied ◽  
Liangyu Hu ◽  
Joshua C McCann ◽  
Daniel W Shike ◽  
...  
Keyword(s):  
Amino Acid ◽  
Beef Cattle ◽  
Protein Degradation ◽  
Insulin Signaling ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Protein Turnover ◽  
Residual Feed Intake ◽  
Ubiquitin Proteasome ◽  
Ruminal Epithelium

Abstract Residual feed intake (RFI) is a widely used measure of feed efficiency in cattle. Although the precise biologic mechanisms associated with improved feed efficiency are not well-known, most-efficient steers (i.e., with low RFI coefficient) downregulate abundance of proteins controlling protein degradation in skeletal muscle. Whether cellular mechanisms controlling protein turnover in ruminal tissue differ by RFI classification is unknown. The aim was to investigate associations between RFI and signaling through the mechanistic target of rapamycin (MTOR) and ubiquitin-proteasome pathways in ruminal epithelium. One hundred and forty-nine Red Angus cattle were allocated to 3 contemporary groups according to sex and herd origin. Animals were offered a finishing diet for 70 d to calculate the RFI coefficient for each. Within each group, the 2 most-efficient (n = 6) and least-efficient animals (n = 6) were selected. Compared with least-efficient animals, the most-efficient animals consumed less feed (P < 0.05; 18.36 vs. 23.39 kg/d DMI). At day 70, plasma samples were collected for insulin concentration analysis. Ruminal epithelium was collected immediately after slaughter to determine abundance and phosphorylation status of 29 proteins associated with MTOR, ubiquitin-proteasome, insulin signaling, and glucose and amino acid transport. Among the proteins involved in cellular protein synthesis, most-efficient animals had lower (P ≤ 0.05) abundance of MTOR, p-MTOR, RPS6KB1, EIF2A, EEF2K, AKT1, and RPS6KB1, whereas MAPK3 tended (P = 0.07) to be lower. In contrast, abundance of p-EEF2K, p-EEF2K:EEF2K, and p-EIF2A:EIF2A in most-efficient animals was greater (P ≤ 0.05). Among proteins catalyzing steps required for protein degradation, the abundance of UBA1, NEDD4, and STUB1 was lower (P ≤ 0.05) and MDM2 tended (P = 0.06) to be lower in most-efficient cattle. Plasma insulin and ruminal epithelium insulin signaling proteins did not differ (P > 0.05) between RFI groups. However, abundance of the insulin-responsive glucose transporter SLC2A4 and the amino acid transporters SLC1A3 and SLC1A5 also was lower (P ≤ 0.05) in most-efficient cattle. Overall, the data indicate that differences in signaling mechanisms controlling protein turnover and nutrient transport in ruminal epithelium are components of feed efficiency in beef cattle.

scholarly journals PSV-18 The role of leptin in feed efficiency and behavior attributes of commercial beef heifers

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 162-162
Author(s):  
Nayan Bhowmik ◽  
Kris A Ringwall ◽  
Carl R Dahlen ◽  
Kendall C Swanson ◽  
Jeffrey A Clapper ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Breeding Season ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Beef Heifers ◽  
Frame Size ◽  
And Behavior ◽  
Plasma Leptin

Abstract Leptin is a 16-kDa-peptide hormone product of the leptin gene (LEP) that is predominantly synthesized by adipose tissues and has known involvement in regulation of feed intake, energy expenditure, reproduction, and immune functions. The objective was to determine the association of leptin genotype (LEP c.73C >T), leptin diplotype (LEPD) and plasma leptin hormone (LEPH) concentration with growth, feed intake, feed efficiency, and behavior characteristics in developing beef heifers. A total of 336 commercial beef heifers were genotyped for the LEP c.73C >T marker. Four single nucleotide polymorphism markers including LEP c.73C >T, ARS-BFGL-NGS-59298 (intron 1), BovineHD0400026029 (upstream) and BovineHD0400026063 (downstream) of LEP were considered for haplotype analysis. Eleven LEPD were identified for this study using parsimony-based analyses. Circulating levels of LEPH were measured on 333 heifers prior to their first breeding season and used to assign low or high concentration group based on population median. Data were analyzed using the mixed procedure of SAS for repeated measures, fixed effects of ancestral breed group (n = 4), dam age category (n = 4), frame size group (n = 4), project cycle nested within birth year (n = 6), week of feed trial × year, LEP (n = 3) or LEPD (n = 11) or LEPH (n = 2), as well as week × LEPH (only for LEPH). There were no significant differences between LEP genotypes (P ≥ 0.11) or LEPD (P ≥ 0.33) for any of the studied traits. Heifers with low LEPH ate fewer meals per day (P = 0.02) and had more DMI per meal (P = 0.04) compared to those with high plasma leptin. Further research is needed to better understand plasma LEPH concentration and its role in feeding behavior attributes. However, circulatory LEPH before the breeding season may serve as a predictor for feeding behavior.

scholarly journals Influence of Residual Feed Intake and Cow Age on Dry Matter Intake Post-Weaning and Peak Lactation of Black Angus Cows

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1822
Author(s):  
Cory T. Parsons ◽  
Julia M. Dafoe ◽  
Samuel A. Wyffels ◽  
Timothy DelCurto ◽  
Darrin L. Boss
Keyword(s):  
Milk Production ◽  
Feed Intake ◽  
Dry Matter ◽  
Free Choice ◽  
Residual Feed Intake ◽  
Beef Cows ◽  
Age Effect ◽  
Dry Matter Intake ◽  
Intake Rate ◽  
Two Stages

We evaluated heifer post-weaning residual feed intake (RFI) classification and cow age on dry matter intake (DMI) at two stages of production. Fifty-nine non-lactating, pregnant, (Study 1) and fifty-four lactating, non-pregnant (Study 2) commercial black Angus beef cows were grouped by age and RFI. Free-choice, hay pellets were fed in a GrowSafe feeding system. In Study 1, cow DMI (kg/d) and intake rate (g/min) displayed a cow age effect (p < 0.01) with an increase in DMI and intake rate with increasing cow age. In Study 2, cow DMI (kg/d) and intake rate (g/min) displayed a cow age effect (p < 0.02) with an increase in DMI and intake rate with increasing cow age. Milk production displayed a cow age × RFI interaction (p < 0.01) where both 5–6-year-old and 8–9-year-old low RFI cows produced more milk than high RFI cows. For both studies, intake and intake behavior were not influenced by RFI (p ≥ 0.16) or cow age × RFI interaction (p ≥ 0.21). In summary, heifer’s post-weaning RFI had minimal effects on beef cattle DMI or intake behavior, however, some differences were observed in milk production.

scholarly journals 268 Administering an appeasing substance to optimize welfare and performance of receiving cattle

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 193-193
Author(s):  
Eduardo Colombo ◽  
Reinaldo F Cooke ◽  
Alice Brandão ◽  
Jacob Wiegand ◽  
Kelsey Schubach ◽  
...  
Keyword(s):  
Feed Intake ◽  
Feed Efficiency ◽  
Treatment Effects ◽  
Average Daily Gain ◽  
Plasma Concentrations ◽  
Feedlot Cattle ◽  
Skin Area ◽  
And Performance ◽  
Antimicrobial Treatments ◽  
Daily Gain

Abstract This experiment evaluated the impacts of bovine appeasing substance (BAS) administration on performance, health, and physiological responses of feedlot cattle during a 45-d receiving period. A total of 342 recently-weaned Angus-influenced steers, originating from 16 cow-calf operations, were obtained from an auction yard on d -1 and road-transported (12 h) to the feedlot. Upon arrival on d 0, body weight (BW) was recorded and steers were ranked by BW and source and assigned to receive BAS (Nutricorp, Araras, SP, Brazil; n = 171) or placebo (diethylene glycol monoethyl ether; CON; n = 171). Treatments (5 mL) were topically applied to the nuchal skin area of each animal. Within treatment, calves were allocated to 1 of 24 drylot pens (12 pens/treatment) and received a free choice total-mixed ration from d 1 to 45. Calves were assessed for bovine respiratory disease (BRD) signs and feed intake was recorded from each pen daily. Steer BW was again recorded on d 1, 7, 17, 31, and 45, whereas blood samples were collected from 5 steers/pen concurrently with each BW assessment. Average daily gain was greater (P = 0.05) in BAS vs. CON calves, although final BW did not differ (P = 0.36) between treatments. No treatment effects were detected for feed intake (P = 0.95), resulting in greater (P = 0.05) feed efficiency in BAS vs. CON steers. No treatment effects were detected (P ≥ 0.37) for plasma concentrations of haptoglobin, whereas plasma cortisol concentrations were greater (P = 0.05) in CON vs. BAS steers on d 7 (treatment × day; P = 0.07). Incidence of BRD was greater (P ≤ 0.05) in BAS vs. CON on d 6 to 10 and d 18 to 21 (treatment × day; P &lt; 0.01), although overall BRD incidence did not differ (P = 0.24) between treatments. The number of antimicrobial treatments required per steer diagnosed with BRD symptoms to recover from sickness was greater (P = 0.04) in CON vs. BAS calves. No treatment differences were detected (P ≥ 0.41) for mortality incidence, or proportion of steers removed from the experiment due to extreme sickness. Results from this experiment indicate BAS administration upon feedlot entry improved average daily gain by enhancing feed efficiency. Administration of BAS facilitated earlier detection of BRD and reduced the need for antimicrobial treatments. Collectively, these results suggest BAS administration as a promising strategy to benefit performance and immunocompetence of feedlot receiving cattle.

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