PSVI-30 Feedlot performance and carcass characteristics of beef steers under intensive management with or without an added nutritional packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 446-446
Author(s):  
Andrea M Osorio ◽  
Kaue Tonelli Nardi ◽  
Igor Gomes Fávero ◽  
Kaliu G Scaranto Silva ◽  
Kymberly D Coello ◽  
...  
Keyword(s):  
Block Design ◽  
Random Effect ◽  
Vitamin B1 ◽  
Carcass Characteristics ◽  
Quality Data ◽  
Experimental Unit ◽  
Beef Steers ◽  
Intensive Management ◽  
Feedlot Performance ◽  
Yeast Saccharomyces Cerevisiae

Abstract The effects of a nutritional packet on performance and carcass characteristics of feedlot beef steers were evaluated. Thirty Angus-crossbred steers (BW = 542 ± 8.4 kg) were used in a randomized complete block design and allocated into pens with SmartFeed (C-Lock; 15 steers/treatment). Steers were consuming a steam-flaked corn-based finishing-diet, ad libitum, for the last 65-d on feed prior to slaughter, in which treatments were: 1) control and 2) a nutritional-packet [0.29% DM basis; live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g); Vitamin C (5.4 g/kg); Vitamin B1 (13.33 g/kg); NaCl (80 g/kg); KCl (80 g/kg)]. Individual BW was recorded every 14 d and carcass quality data was collected at slaughter. Steer was considered the experimental unit. The MIXED procedure of SAS was used with the fixed effect of treatment and the random effect of block. Total DMI was unaffected (P = 0.610) by treatment from d 0–65; however, control steers had greater (P = 0.030) DMI from d 54–65. The G:F was unaffected (P = 0.830) by treatment from d 0–35; however, it was greater (P ≤ 0.001) for steers fed the nutritional packet from d 0–50, and 0–65. Treatment did not affect (P = 0.920) ADG from d 0–35, however it increased (P ≤ 0.001) ADG from d 0–50 and tended (P = 0.060) to increase ADG from d 0–65. Carcass adjusted final BW tended (P = 0.060) to increase by 28% for treated cattle, whereas the Longissimus dorsi area tended to decrease (P = 0.090). No differences (P = 0.240) were observed for fat thickness, while yield-grade (P = 0.03) increased for treated cattle. The nutritional packet appears to improve performance in the final days of feeding steers under intensive management, and energy partitioning may be altered to fat deposition.

309 Nutrient Digestibility of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 168-169
Author(s):  
Kaue T Tonelli Nardi ◽  
Jhones O Onorino Sarturi ◽  
Darren D Henry ◽  
Francine M Ciriaco ◽  
Nelson O Huerta-Leidenz ◽  
...  
Keyword(s):  
Block Design ◽  
Vitamin B1 ◽  
Nutrient Digestibility ◽  
Experimental Unit ◽  
Beef Steers ◽  
Yeast Saccharomyces Cerevisiae ◽  
Finishing Diets ◽  
Time Of Feeding ◽  
Internal Marker ◽  
Feed Samples

Abstract The effects of a nutritional packet fed to beef steers during the final 64 d of the feedlot finishing phase on apparent total tract nutrient digestibility were evaluated. Angus-crossbred steers (n =120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment; pen = experimental unit) in a randomized complete block design. A steam-flaked corn-based finishing diet was fed ad libitum and treatments applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet [containing live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), vitamin C (5.4 g/kg), vitamin B1 (13.33 g/kg), NaCl (80 g/kg) and KCl (80 g/kg)]. The nutritional packet used ground corn as a carrier and was included at 1% of diet DM. Orts were quantified daily (if any) and subtracted from the total dietary DM offered to calculate DM intake. Fecal samples were collected twice daily (0700 and 1700 h) for 5 consecutive days (d 47 to 51) from at least 3 steers within pen. Feed samples were collected daily at time of feeding (0630 h). Fecal and feed samples were composited to represent the collection period, dried (55oC), ground (1 mm), and analyzed to assess DM, OM, NDF, ADF, and hemicellulose. In situ (288 h) iNDF was used as an internal marker to measure apparent total tract nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS. Intake of DM, OM, and fiber components during the digestibility period was not affected (P ≥ 0.44) by treatment. Steers fed the nutritional packet had increased apparent total tract digestibility of OM (P = 0.02), DM (P = 0.01), NDF (P = 0.02), ADF (P = 0.01), and hemicellulose (P = 0.08; tendency). Improved nutrient digestibility without affecting nutrient intake may warrant an enhanced energy deposition in the carcass.

310 Growth Performance and Carcass Characteristics of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 169-169
Author(s):  
Kaue T Tonelli Nardi ◽  
Jhones O Onorino Sarturi ◽  
Darren D Henry ◽  
Francine M Ciriaco ◽  
Nelson O Huerta-Leidenz ◽  
...  
Keyword(s):  
Growth Performance ◽  
Block Design ◽  
Average Daily Gain ◽  
Vitamin B1 ◽  
Carcass Characteristics ◽  
Fat Deposition ◽  
Experimental Unit ◽  
Thiamine Hydrochloride ◽  
Beef Steers ◽  
Finishing Diets

Abstract The effects of a nutritional packet fed to beef steers during the final 64 d of the feedlot finishing phase on growth performance and carcass characteristics were evaluated. Crossbred-Angus steers (n = 120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment) in a randomized complete block design where pen represented the experimental unit. A steam-flaked corn-based finishing diet was fed ad libitum, and treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet (containing live yeast [8.7 Log CFU of Saccharomyces cerevisiae], vitamin C [5.4 g/kg of Ascorbic acid], vitamin B1 [13.33 g/kg of Thiamine hydrochloride], sodium chloride [80 g/kg] and potassium chloride [80 g/kg]). The nutritional packet used ground corn as a carrier and was included at 1 % of diet DM. Orts were quantified daily (if any) and subtracted from the total dietary DM offered to calculate DM intake. Unshrunk BW were collected on d 0, 21, 42 and 64 before daily feeding at 0630 h. Data were analyzed using the GLIMMIX procedure of SAS. Average daily gain (P = 0.89), dry matter intake (P = 0.57) and, gain:feed (P = 0.66) were not affected by the inclusion of the nutritional packet. The 12th rib fat deposition was increased (P ≤ 0.02) for cattle fed the nutritional packet compared with control (15.70 vs. 13.36 mm, respectively). Consequently, calculated yield grade was also increased (P ≤ 0.03) for cattle consuming the nutritional packet (3.32 vs. 3.02). An improved carcass fat-deposition without any deleterious effects on growth performance potentially warrant less days on feed when cattle receive such nutritional packet.

315 Feeding Behavior of Beef Steers Consuming Finishing Diets with Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 170-170
Author(s):  
Igor Gomes Fávero ◽  
Jhones O Onorino Sarturi ◽  
Kaue T Tonelli Nardi ◽  
Daren D Henry ◽  
Kaliu G Scaranto Silva ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Block Design ◽  
Vitamin B1 ◽  
Experimental Unit ◽  
Beef Steers ◽  
Yeast Saccharomyces Cerevisiae ◽  
Eating Time ◽  
Finishing Diets ◽  
D 63 ◽  
Randomized Complete Block Design

Abstract The effects of a nutritional packet fed to beef steers during the feedlot finishing phase (final 64 d) on feeding behavior were evaluated. Crossbred-Angus steers (n = 120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment; pen = experimental unit) in a randomized complete block design. Steers were fed, ad libitum, a steam-flaked corn-based finishing diet and treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of a nutritional packet (containing live yeast [Saccharomyces cerevisiae; 8.7 Log CFU/g], vitamin C [5.4 g/kg], vitamin B1 [13.33 g/kg], NaCl [80 g/kg], and KCl [80 g/kg]). The nutritional packet used ground corn as a carrier and was included at 1% of diet DM. Orts were subtracted from the total dietary DM offered to calculate DM intake. Feeding behavior activities were visually assessed by trained personnel twice (d 27 and d 63) for 24 h, when time spent on each activity was recorded every 5 min. Data were analyzed using the GLIMMIX procedure of SAS. Treatment × period interactions (P ≤ 0.03) were observed for eating time (min/d) and eating rates (min/kg of consumed DM, OM, fiber, and digestible DM, OM, and fiber), in which steers fed the nutritional packet spent less time in such activities on d 27 and more time during the assessment on d 63, compared with control. Regardless of period, steers fed the nutritional packet tended (P = 0.07) to spend less time chewing per kg of digestible ADF. Rumination (P ≥ 0.28), drinking (P ≥ 0.40), active (P ≥ 0.92), and resting (P ≥ 0.53) times were not affected by treatment. The nutritional packet affected eating behavior more intensively during the first 27 d of treatment, and digestible ADF seems to be the main feed-fraction inducing such effect.

305 Methane Emissions and Apparent Total Tract Nutrient Digestibility of Feedlot Beef Steers Under Intensive Management with or Without an Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 166-167
Author(s):  
Andrea M Osorio ◽  
Kaue T Tonelli Nardi ◽  
Igor Gomes Fávero ◽  
Kaliu G Scaranto Silva ◽  
Kymberly D Coello ◽  
...  
Keyword(s):  
Treatment Period ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Methane Emissions ◽  
Nutrient Digestibility ◽  
Experimental Unit ◽  
Beef Steers ◽  
Ch4 Production

Abstract The effects of a nutritional packet were evaluated on CH4 emissions and apparent total tract nutrient digestibility of feedlot beef steers. Thirty Angus-crossbred steers (BW = 542 ± 8.4 kg) were used in a randomized complete block design and allocated into pens equipped with SmartFeed (C-Lock; 15 steers/treatment). Steers were consuming a steam-flaked corn-based diet (88% concentrate DM basis) ad libitum for the last 65 d on feed, and received the following treatments: 1) control and 2) a nutritional packet [0.29% DM basis; live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g); Vitamin C (5.4 g/kg); Vitamin B1 (13.33 g/kg); NaCl (80 g/kg); KCl (80 g/kg)]. Methane emissions and apparent total tract nutrient digestibility were measured during 3 periods with 5-d of collections each. Gas emissions from steers were measured utilizing the SF6 tracer technique. Feed and fecal samples were collected once and twice (0700 h and 1600 h) daily, respectively, to determine digestibility of nutrients using iNDF as an internal marker. Steer was considered the experimental unit. Data were analyzed as repeated measures using the MIXED procedure of SAS with the fixed effects of treatment, period, and their interaction, and the random effect of block. No treatment × period interactions (P ≥ 0.125) were observed for DMI and any of the CH4 production variables (g/day, g/kg BW0.75, g/nutrient intake, and g/nutrient digested). Moreover, treatments did not affect digestibility of DM, OM, or ADF (P ≥ 0.300); however, digestibility of NDF was increased for treated cattle (P = 0.013), which resulted in a tendency (P = 0.098) to decrease CH4 production in g per kg NDF intake and decreased (P = 0.020) grams CH4 per kg NDF digested. The nutritional packet may be altering ruminal fermentation on intensively managed steers and improving fiber digestibility, which can have benefits on CH4 emission intensity.

scholarly journals 349 The use of low antioxidant mineral concentrations in the growing diet as a method to increase marbling deposition in feedlot cattle

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 141-142
Author(s):  
Jerad R Jaborek ◽  
Alejandro E Relling
Keyword(s):  
Control Diet ◽  
Random Effect ◽  
Dietary Treatment ◽  
Basal Diet ◽  
Feedlot Cattle ◽  
Experimental Unit ◽  
Beef Steers ◽  
Feedlot Performance ◽  
Dietary Treatments

Abstract The presence of reactive oxygen species has been associated with the differentiation of pre-adipocytes into lipid filled mature adipocytes in vitro. We hypothesized offering a diet without supplemental antioxidant minerals (Cu, Mg, Zn, and Se) to steers during the growing phase, a time when intramuscular fat cells are believed to be proliferating, would promote differentiation of pre-adipocytes, leading to more desirable marbling scores compared with steers supplemented to meet their mineral requirements. After adaptation to the feedlot, 168 Sim-Angus steers were divided into four weight blocks, placed in one of twenty-four pens, and randomly assigned a dietary treatment. Dietary treatments were: 1) no supplemental (Cu, Mg, Zn, and Se) minerals; 2) control diet with supplemented minerals to meet the mineral requirements of growing beef steers (NRC, 2016); 3) Cu, Mg, Zn, and Se concentrations supplemented at twice the concentration of the control diet. After dietary treatments were applied for the 4-wk long growing phase, steers were offered a common finishing diet until reaching a similar backfat thickness until harvest. Feedlot performance and carcass data were analyzed in SAS with pen as the experimental unit in the following model: Yij = μ+Di+wj+eij, where Di was the fixed effect of diet, wj was the random effect of weight block, and eij was the random error. No significant (P > 0.35) treatment effects were found for feedlot performance and carcass measurements. The feedstuffs in the basal diet may have contained sufficient concentrations of antioxidant minerals to meet the mineral requirements of the steers and mask differences in marbling. Additionally, offering a similar diet during the finishing period may have resulted in compensatory marbling growth, which offset marbling differences after the growing phase and resulted in uniform marbling accumulation across dietary treatments.

scholarly journals PSVII-9 Effects of a multi-species direct-fed microbial on growth performance and carcass characteristics of grow-finish pigs

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 216-216
Author(s):  
Mariana Boscato Menegat ◽  
Joel M DeRouchey ◽  
Jason C Woodworth ◽  
Mike D Tokach ◽  
Steve S Dritz ◽  
...  
Keyword(s):  
Growth Performance ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Block Design ◽  
Control Diet ◽  
Random Effect ◽  
Carcass Characteristics ◽  
Experimental Unit ◽  
Feeding Duration ◽  
Corn Distillers

Abstract This study was conducted to determine the effects of a multi-species direct-fed microbial (DFM) product based on lactic acid bacteria and Bacillus subtilis on growth performance and carcass characteristics of grow-finish pigs. A total of 1,188 pigs (PIC 359 × 1050; initially 25.8 kg BW) were used in a 121-d growth trial with 27 pigs/pen and 22 pens/treatment. Pigs were allotted to treatments based on initial BW in a randomized complete block design. Treatments included a control diet and the control diet with added DFM (BiOWiSH Technologies Inc., Cincinnati, OH) included at 0.055% of the diet at the expense of corn. Diets were based on corn, distillers dried grains with solubles, and soybean meal and fed in four dietary phases. Data were analyzed using a linear mixed model (PROC GLIMMIX, SAS®) with treatment as fixed effect, block as random effect, and pen as experimental unit. Overall (d 0 to 121), pigs fed the control diet had greater ADG (P < 0.05) and final BW (P < 0.001) compared to pigs fed the DFM diet (Table 1). There was no evidence for differences (P > 0.05) in ADFI or G:F between treatments. The difference in final BW resulted in heavier (P < 0.05) HCW in control pigs compared to DFM pigs, but no evidence for differences (P > 0.05) was observed in carcass yield, backfat, loin depth, and percentage lean between treatments. In conclusion, the inclusion of this multi-species DFM in growing-finishing diets reduced ADG in this commercial study. This response could be related to inclusion rate, feeding duration, or other factors not identified in this study, warranting further research to characterize the effects on pig performance.

scholarly journals 230 Effects of encapsulated calcium-ammonium nitrate on performance and methane production of beef steers grazing mixed winter forage

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 166-167
Author(s):  
Andrea M Osorio Doblado ◽  
Sebastian E Mejia-Turcios ◽  
Miranda K Stotz ◽  
David Vargas ◽  
Rafael Canonenco de Araujo ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Methane Production ◽  
Repeated Measures ◽  
Block Design ◽  
Random Effect ◽  
Experimental Unit ◽  
Beef Steers ◽  
Adaptation Period ◽  
Calcium Ammonium Nitrate ◽  
Supplement Intake

Abstract The effects of encapsulated calcium-ammonium nitrate (eCAN) on in vivo methane production and performance were evaluated. A generalized randomized block design was used with beef steers grazing a mixed winter forage (Triticum aestivum, Triticosecale rimpaui, and Secale cereale) for 49 d. Thirty-six Angus-crossbred steers (332 ± 53 kg) were blocked by BW and randomly assigned to 1 of 3 treatments: 1) winter pasture + corn (WC), 2) WC + 328 mg/kg of BW eCAN (WCN) and 3) WC + 124 mg/kg of BW UREA (WCU), all supplemented with corn (0.3% BW treatments). Treatments WCN and WCU were isonitrogenous. A 14d adaptation period was used to adapt cattle to treatments. Methane emissions were measured using the sulfur hexafluoride tracer technique. Blood samples and BW were taken at d 0, 24, 35, and 49. Supplemental corn and NPN orts were collected daily. Data were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effect of pasture (block); BUN, supplement intake and CP intake were analyzed with repeated measures. Steer was considered the experimental unit. Methane production was not different (P &gt; 0.05) considering g/d, g/kg of BW, g/kg of MBW, or g/kg of ADG. Treatments did not affect ADG (P = 0.941). Supplement intake was affected by treatment (P &lt; 0.001), with WC (0.979 kg) being greater compared to WCU (0.887 kg) and WCN (0.706 kg). Total CP intake increased (P &lt; 0.001) with WCU (0.155 kg) and WCN (0.116 kg), compared to WC (0.074 kg), which did not have a non-protein source. Blood urea nitrogen was affected by day, with d 24 (18.598 mg/dL) being greater compared to d 0 (8.215 mg/dL), 35 (10.549 mg/dL) and 49 (14.5744 mg/dL). The eCAN did not effectively replace urea as a NPN source to mitigate enteric methane.

287 Effects of a Novel Rumen-protected Folic Acid Supplement on Feedlot Performance and Carcass Characteristics of Beef Steers

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 160-161
Author(s):  
Erin L Deters ◽  
Emma Niedermayer ◽  
Olivia N Genther-Schroeder ◽  
Christopher Blank ◽  
Remy Carmichael ◽  
...  
Keyword(s):  
Folic Acid ◽  
Liver Abscess ◽  
Fixed Effects ◽  
Block Design ◽  
Average Daily Gain ◽  
Experimental Unit ◽  
Beef Steers ◽  
Feedlot Performance ◽  
Growing Period ◽  
Dietary Treatments

Abstract To assess effects of a novel rumen-protected folic acid (RPFA) supplement, 180 Angus-cross steers (292 ± 18 kg) were blocked by body weight to pens and randomly assigned to dietary treatments (n = 6 pens/treatment): target intake of 0 (CON), 30 (RPFA-30), 60 (RPFA-60), 90 (RPFA-90), 120 (RPFA-120), or 150 (RPFA-150) mg RPFA·steer-1·d-1. Steers were weighed on d -1, 0, 55, 56 (end of growing), 86, 87, 181, and 182. Liver and blood were collected (two steers/pen) before trial initiation and at the end of growing and finishing. Data were analyzed as a randomized complete block design using ProcMixed of SAS (fixed effects of treatment and block; experimental unit of pen). Liver abscess scores were analyzed using ProcGenmod of SAS. Contrast statements evaluated polynomial effects of RPFA and compared CON vs. RPFA-30. At end of growing, RPFA linearly increased plasma folic acid (P &lt; 0.01) and linearly decreased plasma glucose (P = 0.01). Liver folic acid concentrations at end of growing were greatest for CON, RPFA-90, and RPFA-120 (cubic P = 0.01), and growing period (d 0 to 56) average daily gain and gain:feed were greatest for CON and RPFA-120 (cubic P ≤ 0.03). At end of finishing, RPFA linearly increased plasma folic acid concentrations (P &lt; 0.01), and liver folic acid concentrations were lesser for CON vs. RPFA-30 (P = 0.04). Severe liver abscess percentage tended to be greater for CON vs. RPFA-30 (P = 0.09), while dressing percent was lesser for CON vs. RPFA-30 (P = 0.04). Overall (d 0 to 182) carcass-adjusted gain:feed tended to be greater for CON vs. RPFA-30 (P = 0.09). Although RPFA increased plasma folic acid concentrations throughout the study, feedlot performance was not improved, possibly due to low vitamin B12 status (plasma &lt; 200 pg/mL) of steers, regardless of treatment.

270 Evaluation of Steer Implant Strategies for Long-season Grazing of Cool-season Annuals

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 144-144
Author(s):  
Taylor J Garcia ◽  
Ryan R Reuter ◽  
Frank White ◽  
Ken Blue ◽  
Daniel Rivera
Keyword(s):  
Random Effect ◽  
Carcass Characteristics ◽  
Cost Effective ◽  
Single Component ◽  
Experimental Unit ◽  
Beef Steers ◽  
Marbling Score ◽  
Cool Season ◽  
Significant Difference ◽  
Plant Data

Abstract The objective of this study was to determine the relative effects of stocker-phase implant strategies on growth and carcass characteristics of beef steers. In each of 2 locations (OK and MS), steers were grazed on cool-season annual pastures in fall 2018 through spring 2019. Steers (n = 300 in MS, n = 240 in OK) were randomly assigned to one of three implant treatments, 1) a single Synovex® One Grass implant at d 0, 2) a single Component® TE-G with Tylan implant at d 0, or 3) a reimplant treatment receiving Component® TE-G with Tylan at d 0 and again at d 82 (OK) or 85 (MS). Steers from each treatment were commingled in 2 (OK) or 3 (MS) pastures for 159 (OK) or 161 d (MS). Following grazing, steers were shipped to a commercial feedyard for finishing, sorted into 3 pens based on BW with each treatment equally represented in each pen, and were managed according to that site’s BMPs. Steers from all treatments were implanted identically in the feedyard. Steers were slaughtered when the pen was visually estimated to be at 1 cm backfat. Carcass data of individuals were collected by camera grading equipment in the packing plant. Data were analyzed as a completely random design with animal as the experimental unit, treatment as a fixed effect, and pasture within location as a random effect. Marbling score tended to be greater in the single Component® TE-G with Tylan (treatment 2) vs. the other 2 treatments (425 vs 408 and 410, P = 0.07). No other production variables, including stocker-phase ADG, approached a significant difference (P &gt; 0.39). No evidence was found to recommend stocker-phase reimplanting even in relatively long stocker phases with high ADG, and producers should consider selecting the most cost-effective implant at grazing initiation.

scholarly journals Investigating the effects of a novel rumen-protected folic acid supplement on feedlot performance and carcass characteristics of beef steers

2021 ◽  
Author(s):  
Erin L Deters ◽  
Emma K Niedermayer ◽  
Olivia N Genther-Schroeder ◽  
Christopher P Blank ◽  
Remy N Carmichael ◽  
...  
Keyword(s):  
Folic Acid ◽  
Vitamin B12 ◽  
Fixed Effects ◽  
Transition Period ◽  
Block Design ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Experimental Unit ◽  
Plasma Vitamin ◽  
Feedlot Performance

Abstract Angus-crossbred steers (n = 180; 292 ± 18 kg) from a single ranch were used to investigate the effects of a novel rumen-protected folic acid (RPFA) supplement on feedlot performance and carcass characteristics. On d 0, steers were blocked by body weight to pens (5 steers/pen), and pens within a block were randomly assigned to dietary treatments (n = 6 pens/treatment): target intake of 0 (CON), 30 (RPFA-30), 60 (RPFA-60), 90 (RPFA-90), 120 (RPFA-120), or 150 (RPFA-150) mg RPFA·steer -1·d -1. Steers were weighed before feeding on d -1, 0, 55, 56, 86, 87, 181, and 182. Pen average daily gain (ADG), dry matter intake (DMI), and gain:feed (G:F) were calculated for growing (d 0 to 56), dietary transition (d 56 to 87), finishing (d 87 to 182), and overall (d 0 to 182). Liver and blood samples were collected from two steers/pen before trial initiation and at the end of growing and finishing. Steers were slaughtered on d 183, and carcass data were collected after a 48-h chill. Data were analyzed as a randomized complete block design using ProcMixed of SAS 9.4 (fixed effects of treatment and block; experimental unit of pen). Liver abscess scores were analyzed using the Genmod Procedure of SAS 9.4. Contrast statements assessed the polynomial effects of RPFA. Supplemental RPFA linearly increased plasma folate at the end of growing and finishing (P &lt; 0.01), and linearly decreased plasma glucose at the end of growing (P = 0.01). There was a cubic effect of RPFA on liver folate at the end of growing (P = 0.01), driven by lesser concentrations for RPFA-30, RPFA-60, and RPFA-150. Growing period ADG and G:F were greatest for CON and RPFA-120 (cubic P ≤ 0.03). Transition period DMI was linearly increased due to RPFA (P = 0.05). There was a tendency for a cubic effect of RPFA on the percentage of livers with no abscesses (P = 0.06), driven by a greater percentage of non-abscessed livers in RPFA-30 and RPFA-60. Despite supplementing 1 mg Co/kg DM, and regardless of treatment, plasma vitamin B12 concentrations were low (&lt; 200 pg/mL), which may have influenced the response to RPFA as vitamin B12 is essential for recycling of folate.

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