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This study evaluates the partial replacement of steam-flaked corn (SFC) with increasing dried distillers grains plus solubles (DDGS) levels in growing-finishing diets for calf-fed Holstein steers. Two experiments were conducted. In trial 1, 100 Holstein calves (136 ± 7 kg) were used to evaluate the effect of DDGS as a metabolizable protein source on cattle growth performance, and dietary energetics of calf-fed Holstein steers during the initial 111 d growing phase. Four dietary levels of DDGS were evaluated (10, 15, 20, and 25%, dry matter basis), replacing SFC (flake density, 0.31 kg/L). In trial 2, four Holstein steers (368 ± 20 kg) with cannulas in the rumen and proximal duodenum were used to evaluate treatment effects on characteristics of ruminal and total tract digestion of organic matter (OM), neutral detergent fiber, nitrogen (N), and indispensable amino acid supply to the small intestine. The increasing level of DDGS did not affect (P ≥ 0.13) average daily gain, gain efficiency, and estimated dietary net energy values. Replacement of SFC with increasing levels of DDGS decreased (linear; P = 0.01) ruminal OM digestion. There was no treatment effect on the flow of microbial nitrogen to the small intestine (P = 0.34) and ruminal microbial efficiency (P = 0.79). However, increasing levels of DDGS in the diet increased (linear; P ≤ 0.04) flow of methionine, histidine, phenylalanine, threonine, leucine, isoleucine, and valine but did not affect (P = 0.74) intestinal supply of lysine. Increasing DDGS in the diet increased (linear, P < 0.01) flow of N to the small intestine but decreased (linear; P < 0.01) ruminal N efficiency. Replacing SFC with DDGS increased intake and amino acid leaving the abomasum. Still, this effect was not sufficient to increase the growth performance of calf-fed Holstein during the first 111 d on feed. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the influence of supplemental flavomycin on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics of calf-fed Holstein steers. One hundred Holstein steers (123 ± 7 kg) were balanced by weight and assigned to 20 pens. Dietary treatments consisted of a steam flaked corn-based diet supplemented with (dry matter basis): 1) control, no feed additive; 2) 6.6 mg/kg flavomycin; 3) 13.2 mg/kg flavomycin, and 4) 30 mg/kg monensin (MON). There were no treatment effects (P ≥ 0.17) on live weight, average daily gain (ADG), and gain efficiency. Flavomycin did not affect dry matter intake (DMI; P ≥ 0.24). Flavomycin supplementation did not affect (P ≥ 0.37) the ratio of observed vs. expected DMI. However, MON decreased (P = 0.02) observed vs. expected DMI by 3.7%. There were no treatment effects (P ≥ 0.44) on ruminal pH or temperature. Flavomycin did not affect (P ≥ 0.13) carcass characteristics and liver abscess among steers. Four Holstein steers (463 ± 20 kg) with ruminal cannulas were used in 4 × 4 Latin square experiment to study treatment effects on site and extent of digestion, ruminal pH, and volatile fatty acid (VFA) molar proportions. Dietary treatments were the same as experiment 1. Flavomycin tended to increase (linear effect, P = 0.07) ruminal organic matter (OM) digestion, associated with increased (linear effect, P < 0.01) ruminal starch digestion. Supplementing flavomycin at 13.2 mg/kg decreased net microbial N synthesis (quadratic effect, P = 0.03). Compared with control, MON tended to increase (P = 0.10) ruminal neutral detergent fiber (NDF) digestion and increased (P < 0.01) ruminal starch digestion. Monensin did not affect (P = 0.39) net microbial N synthesis, but decreased (P = 0.01) ruminal degradation of feed nitrogen (N). There were no treatment effects (P > 0.10) on total tract apparent digestion of DM, OM, NDF, and starch. Flavomycin decreased ruminal pH (quadratic effect, P < 0.01) measured 4 h postprandial. Compared with control, MON increased ruminal pH (P = 0.03). Flavomycin increased (linear effect, P = 0.03) ruminal propionate molar proportion and decreased (linear effect, P ≤ 0.04) ruminal molar proportions of acetate and butyrate, and decreased (linear effect, P = 0.02) acetate:propionate molar ratio and estimated methane production. We conclude that supplementing flavomycin at 6.6 or 13.2 mg/kg had no major effects on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics. [ABSTRACT FROM AUTHOR]

The objective of the current study was to investigate the effects of supplemental rumen-protected lysine and methionine (SMART) and ractopaminehydrochloride (RAC) on cattle growth performance and carcass characteristics of finishing calf-fed Holstein steers. Calf-fed Holstein steer calves [n = 96; body weight (BW) = 466 ± 29 kg] were used to evaluate the interaction of ractopamine and supplemental methionine and lysine on growth performance and carcass characteristics. Steers were blocked by initial off-truck BW and assigned within BW grouping to 16 pens (6 steers/pen). From d 1 to 67, all steers received the basal steam-flaked corn-based finishing diet. From d 68 to harvest (d 103), steers received experimental diets consisting of two levels of RAC (0 vs. 300 mg/hd/d; Optaflexx, Elanco US, Inc., Greenfield, IN) and two levels of supplemental SMART (0 vs. 0.67% DM basis, Smartamine ML Adisseo, Alpharetta, GA). There was an interaction (P = 0.04) between RAC and SMART supplementation, where cattle fed the combination of both supplements had an increase in dry matter intake (DMI) compared with cattle fed either RAC or SMART. However, there was no interaction (P ≥ 0.17) of treatments in other growth performance or carcass characteristic variables evaluated in the study. Carcass adjusted average daily gain (ADG) and energy efficiency of the diet increased (P ≤ 0.02) on cattle supplemented with SMART. Moreover, carcass-adjusted final BW and feed efficiency, as well as energy efficiency, increased (P ≤ 0.05) on cattle supplemented with RAC. However, neither SMART nor RAC supplementation affected (P ≥ 0.13) cattle DMI. Both SMART and RAC supplementation increased (P ≤ 0.03) carcass weight, with no effect (P ≥ 0.17) in other carcass characteristics. In conclusion, both SMART and RAC supplementation enhances cattle growth performance with no detrimental effects on carcass characteristics of calf-fed Holstein steers. [ABSTRACT FROM AUTHOR]

Objective of the current study was to evaluate the effects of tannin supplementation on cattle growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. One hundred and sixty dairy steer calves with initial body weight (IBW) of 129.85 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 10 pens per dietary treatment). Dietary treatments were: 1) Control (no additives); 2) MON (30 mg/kg monensin); 3) TAN (15 g/kg ByPRO; 70% condensed tannin; Silvateam USA, Tontitown, AR); and 4) MON+TAN (30 mg/kg monensin + 15 g/kg ByPRO). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feed. There were no effects (P = 0.13) of dietary treatment on final BW (615 ± 22 kg), overall average daily gain (1.48 ± 0.07 kg/day), overall dry matter intake (7.93 ± 0.39 kg/day), overall gain to feed ratio (0.187 ± 0.07), and overall observed vs. expected net energy for maintenance and gain (1.00 ± 0.03 and 1.00 ± 0.04, respectively). However, cattle receiving MON or MON+TAN supplementation increased (P = 0.04) BW and gain to feed ratio in the first 112 days on feed compared with cattle in the control treatment. Moreover, cattle in the 2 dietary treatments receiving monensin supplementation tended (P = 0.09) to increase average daily gain and gain to feed ratio on the first 112 days on feed compared with cattle in the control treatment. There were no effects (P = 0.22) of feed additive supplementation on hot carcass weight (380.7 ± 14.7 kg), dressing percentage (61.83 ± 1.05%), kidney, pelvic, and heart fat (3.32 ± 0.19%), backfat thickness (0.73 ± 0.12 cm), longissimus muscle area (83 ± 4.83 cm2), marbling score (494 ± 48), and calculated yield grade (2.94 ± 0.24). Moreover, there were no effects (P = 0.55) of dietary treatment on percent of liver abscess incidence, regardless of diet, calf-fed steers in the current study had 3.75% of liver with abscess. [ABSTRACT FROM AUTHOR]

Objective of the current study was to evaluate the effects of cattle breed (Holstein vs Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. Eighty Holstein (HOL), initial body weight (IBW) of 128.7 ± 3 kg, and 80 Angus × Holstein cross (CROS) with IBW of 127.1 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 20 pens per breed). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feeding. There was no effect (P = 0.13) of cattle breed on final body weight (615 ± 22 kg) and overall average daily gain (1.48 ± 0.07 kg/day). However, calf-fed HOL steers had greater (P = 0.04) overall dry matter intake compared with calf-fed CROS steers (8.06 vs. 7.79 ± 0.39 kg/day; respectively). Therefore, calf fed CROS steers had greater (P = 0.01) grain to feed ratio compared with calf-fed HOL steers (0.192 vs. 0.182 ± 0.005; respectively). Moreover, calffed CROS steers had greater (P < 0.01) utilization of dietary net energy for maintenance (2.29 vs. 2.29 ± 0.06 Mcal/kg; respectively) and gain (1.51 vs 1.61 ± 0.06 Mcal/kg; respectively) compared with calf-fed HOL steers. Calf-fed CROS steers had greater (P = 0.02) hot carcass weight (HCW; 386.3 vs. 375.2 ± 14.7 kg; respectively), dressing percentage (DP; 62.3 vs. 61.4 ± 1.05%; respectively), longissimus muscle area (LMA; 86.9 vs. 79.1 ± 4.83 cm2; respectively), backfat thickness (0.89 vs. 0.55 ± 0.12; respectively), and marbling score (538 vs. 449 ± 48; respectively). However, there was no effect (P = 0.26) of cattle breed on calculated USDA yield grade (2.94 ± 0.24). Moreover, there was no effect (P = 0.39) of cattle breed on incidence of liver abscesses. Therefore, cross breeding calf-fed Angus × Holstein increased HCW, DP, LMA, and marbling compared with purebred calf-fed Holstein steers. Moreover, regardless of cattle breed, calf-fed steers in the current study had only 3.75% of liver with abscess. [ABSTRACT FROM AUTHOR]

Objectives were to evaluate the relationship between pen mud accumulation and growth performance of calf-fed Holstein steers during the extreme heat characteristic of the months of August and September in the Southern California desert region. Holstein steers (n = 105; initial BW = 443 ±17 kg) were utilized in 28-d experiment (August 17 - September 14, 2021). Steers were blocked by initial shrunk weight (220 d before the initiation of the experiment) and randomly assigned to 21 pens (5 steers per pen). Pens were 62 m2 with 25 m2 overhead shade, automatic waterers and 2.4 m fence-line feed bunks. All steers were fed a steam-flaked corn-based growing-finishing diet. A bolus measuring temperature activity (smaXtec Basic, Smaxtec Animal Care GmbH, Austria) was placed in the rumen of each steer 55 d before the initiation of the experiment (June 22, 2021). Mud scores were recorded weekly by visual inspection. Mud score was determined as the percentage of pens surface area covered with mud. Scores were determined as follows: 1 - 0 to 20% of pen covered by mud; 2 - 21 to 40% of pen covered by mud; 3 - 41 to 60% of pen covered by mud; 4 - 61 to 80% of pen covered by mud; 5 - 81 to 100% of pen covered by mud. Ambient temperature averaged 33.2 ±2.3° C for the experimental period. Temperature of dry pen surfaces was greater than that of muddy surfaces (50.3 vs 20.4° C, respectively, P < 0.01). The relationship between ruminal temperature and pen mud score was not appreciable (P = 0.56). However, ADG was greater with a pen mud score of 2. Average daily gain decreased as pen mud score increased (r2 = 0.55). Similarly, feed efficiency was greatest in pens with a pen mud score of 2. Greater pen mud scores resulted in decreased feed efficiency (r2 = 0.56). [ABSTRACT FROM AUTHOR]