Feedlot Growth Performance Research Articles

Effects of Encapsulated Methionine on Skeletal Muscle Growth and Development and Subsequent Feedlot Performance and Carcass Characteristics in Beef Steers.

Simple SummaryResearch investigating the effects of amino acids in growing and finishing beef cattle is not a new topic. Many studies suggest that in cattle fed a concentrate-based diet, lysine is the most limiting amino acid followed by methionine. When considering supplementing amino acids to growing-finishing beef cattle, the amino acids must be protected from ruminal microbial consumption for the beef animal to be able to absorb the amino acids in the small intestine. The regulation of skeletal muscle growth is a multifaceted, complex process controlled through many signaling cascades. One major process involved in muscle growth is the mammalian target of the rapamycin (mTOR) signaling pathway. The objectives of these studies were to investigate the role of encapsulated methionine on feedlot growth performance and carcass characteristics and to elucidate the role of methionine supplementation on the mTOR signaling pathway and skeletal muscle development in feedlot steers during the finishing phase.Two studies were conducted to evaluate the effect of encapsulated methionine on live performance, carcass characteristics, and skeletal muscle development in feedlot steers. In Experiment 1, 128 crossbred steers (body weight [BW] = 341 ± 36.7 kg) were used in a randomized complete block design and supplemented with 0, 4, 8, or 12 g/(head day [d]) of ruminally protected methionine (0MET, 4MET, 8MET, and 12MET, respectively) for 111 d or 139 d. In Exp. 2, 20 steers (BW = 457 ± 58 kg) were stratified by BW and randomly assigned to either the 0MET or 8MET treatment; longissimus muscle (LM) biopsies were collected on d 0, 14, 28, 42, and 56, and analyzed for mRNA and protein expression. Additionally, immunohistochemical analysis was performed to measure fiber type area and distribution as well as the density of muscle nuclei and satellite cells (Myf5, Pax7, and Myf5/Pax7). In Experiment 1, no significant differences were observed for live performance (p ≥ 0.09). There was, however, a linear relationship between LM area and methionine supplementation (p = 0.04), with a 9% increase in the area when steers were supplemented with 12MET compared to 0MET. In Exp. 2, There were no treatment × day interactions (p ≥ 0.10) for expression of mRNA or protein abundance. Although mRNA expression and protein abundance of all genes were influenced by day (p ≤ 0.04), methionine supplementation did not have a significant effect (p ≥ 0.08). There was a significant treatment × day interaction for distribution of MHC-I fibers (p = 0.03), where 8MET supplemented cattle had a greater proportion of MHC-I fibers after 56 d of supplementation than did 0MET steers. Cross-sectional area was increased over time regardless of fiber type (p < 0.01) but was unaffected by treatment (p ≥ 0.36). While nuclei density was not impacted by treatment (p = 0.55), the density of myonuclei increased nearly 55% in 8MET supplemented cattle (p = 0.05). The density of Myf5 positive satellite cells tended to decrease with methionine supplementation (p = 0.10), while the density of Pax7 expressing cells tended to increase (p = 0.09). These results indicate that encapsulated methionine supplementation may influence markers of skeletal muscle growth, and potential improvements in the LM area may exist.

Effects of feeding dry-rolled corn or whole shelled corn on feedlot performance, carcass characteristics, and eating behavior of finishing Holstein steers

The objective was to determine the effect of corn processing method on feedlot growth performance, carcass characteristics, estimated starch digestibility, and eating behavior of Holstein steers fed a corn-based diet. Seventy-nine Holstein steers (average initial BW = 451 ± 6 kg) were assigned randomly to 1 of 2 treatments: (1) whole shelled corn (WSC) or (2) dry-rolled corn (DRC). Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). No effect ( P ≥ 0.55) of treatment on final BW was detected. No differences ( P ≥ 0.18) in ADG, DMI, or G:F were detected. However, Holstein steers fed DRC had 28% less ( P ≤ 0.01) fecal starch and an 8% greater ( P ≤ 0.01) estimated total-tract starch digestibility when compared with those fed WSC. In addition, Holstein steers fed WSC ate 10% fewer ( P < 0.01) meals that were 10% larger ( P < 0.01) and took 17% longer ( P < 0.01) to eat than those fed DRC. Corn processing method failed to significantly alter ( P ≥ 0.19) hot carcass weight, DP, marbling, or QG of the carcass. However, steers fed WSC had a greater ( P ≤ 0.01) LM area and less ( P ≤ 0.05) s.c. fat thickness, calculated YG, and calculated empty body fat at slaughter. Despite the increased fecal starch and decreased estimated starch digestibility, feeding the WSC-based diet to finishing Holstein steers did not alter feedlot growth performance or hot carcass weight when compared with feeding the DRC-based diet. Therefore, feeding WSC may be an alternative for beef cattle producers who cannot afford to process corn for the diets of finishing animals.

105 A comparison of long-acting growth-promoting implants and re-implant programs in finishing heifers fed for 184 days

Abstract Yearling beef heifers (n = 6,239) were used in a randomized complete block design experiment to evaluate the effects of long-acting implants on feedlot growth performance and carcass characteristics when compared with re-implant programs. Heifers (initial BW = 324 kg, SEM = 0.85) were randomized to 1 of 4 implant treatments with 12 pens/treatment: 1) Revalor-IH (80 mg trenbolone acetate [TBA], 8 mg estradiol [E]) at initial processing followed by a Revalor-200 (200 mg TBA, 20 mg E) 90 d later (IH/200); 2) Revalor-200 at initial processing followed by a Revalor-200 90 d later (200/200); 3) Revalor-XH (200 mg TBA, 20 mg E) at initial processing (XH); and 4) Synovex One Feedlot (200 mg TBA, 20 mg E) at initial processing (ONE). Revalor-XH and Synovex One are long-acting implants designed to extend hormone release, eliminating the need to re-implant cattle. After initial processing, XH and ONE heifers were not removed from their pens until harvest. Final BW (556 kg), DMI (7.95 kg/d), ADG (1.26 kg), and feed efficiency (0.158) did not differ (P &amp;gt; 0.23) among treatments. Hot carcass weight (HCW) was greater (P &amp;lt; 0.10) for 200/200 (364 kg) than XH (361 kg) and ONE (360 kg), with no other differences (P &amp;gt; 0.10) in HCW among treatments. Dressing percentage (DP) and longissimus muscle (LM) area were greater (P &amp;lt; 0.01) for 200/200 than all other treatments, and greater for IH/200 than XH and ONE. Marbling score was reduced and average yield grade (YG) was improved (P &amp;lt; 0.01) for 200/200 vs. all other treatments and for IH/200 vs. XH and ONE. Compared with re-implant programs, long-acting implants decreased DP and LM area, increased marbling score and YG, and did not differ in final BW. The Revalor-200/200 re-implant program resulted in improved HCW when compared with long-acting implants.

43 Effects of steroidal implants on feedlot growth performance, carcass characteristics, and serum and meat estradiol-17β concentrations of Holstein steers

Abstract Objectives were to determine the effects of implants on growth performance, carcass characteristics, and estradiol-17β (E2) concentrations in the serum and longissimus muscle of Holstein steers fed a grain-based diet. Seventy Holstein steers (initial BW = 275 ± 6.4 kg) were assigned to treatments: (1) Implanted on d 0 with Component TE-IS with Tylan (Elanco Animal Health, Greenfield, IN) and on d 84 with Component TE-S with Tylan (Elanco Animal Health) of the experiment; or (2) not implanted (control). Implanted Holstein steers were heavier (P ≤ 0.01) than nonimplanted Holstein steers on d 84, at time of reimplant, and at the end of the experiment (d 186). Implanting Holstein steers increased (P &amp;lt; 0.01) average daily gain (ADG) and dry matter intake (DMI) without affecting (P = 31) gain-to-feed ratio (G:F) when compared to steers that were not implanted. Carcasses from implanted Holstein steers had greater (P &amp;lt; 0.01) hot carcass weights (HCW) and longissimus muscle (LM) area than carcasses from nonimplanted steers. Implanting did not affect (P ≥ 0.21) other carcass characteristics. There was an increase (P = 0.03) of 1.3 pg of E2/g of muscle when LM from implanted Holstein steers was compared to LM from nonimplanted steers. There was an implant × day interaction (P &amp;lt; 0.01) in circulating serum E2 concentrations. Serum E2 concentrations remained relatively constant in nonimplanted Holstein steers. In implanted steers, serum E2 concentrations increased (P &amp;lt; 0.01) after each implant. Serum E2 peaked at 28 d after the first implant and then declined after d 56. Implanting Holstein steers fed grain-based diets increased ADG, HCW, and LM area due to increased circulating E2 concentrations. Implants did increase LM E2 concentrations; however, changes were minimal compared to E2 concentrations in other human foods and were not great enough to warrant concerns regarding meat consumption from implanted animals.

82 Evaluation of feeding immunoglobulin-Y to Holstein feeder cattle for the control of liver abscesses &amp; reduction of macrolide-resistant bacteria dissemination

Abstract Despite the regular use of macrolide-antibiotics in the diets of feedlot cattle, liver abscesses persist representing a financial burden to both pre- and post-mortem sectors of the beef industry. Alternative strategies, which simultaneously address liver infections and reduce the dissemination of antibiotic-resistant bacteria, are needed. An immunoglobulin-Y (IGY) product, developed to target Fusobacterium necrophorum and Trueperella pyogenes, was evaluated for the control of liver abscesses and its effect on macrolide-resistant Enterococcus growth from feces. Sixty-four Holstein steers (Initial BW= 384±13.5kg) consuming a finishing diet (90% concentrate) for 188 days (Final BW= 660±42 kg) were used in a completely randomized design where treatments included: TYL (Tylosin phosphate fed at 90 mg/hd/day; n = 32) or IGY (fed at 2.5g/hd/day; n = 32).Feed intake was recorded daily and BW was recorded every 28 days until slaughter. After 150 d on treatment fecal samples were randomly obtained from each treatment group four times (n = 40) and cultured on bile-esculine agar enriched with 8 μg/mL of erythromycin. Continuous variables of feedlot growth performance, carcass data and bacterial growth were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effects of steer or sampling day, respectively. Ordinal carcass data was analyzed using the FREQ procedure of SAS observing the Cochran-Mantel-Haenszel value. Treatment did not affect DMI (P = 0.21), ADG (P = 0.50) or G:F (P = 0.36). Treatment neither affected hot carcass weight (P = 0.37) nor longissimus muscle area (P = 0.25). However, TYL resulted in greater back fat thickness than IGY (0.32 vs. 0.23 in.; P &amp;lt; 0.02) and consequently greater numerical yield grade (P &amp;lt; 0.02). Quality grade was not affected by treatment (P = 0.65). No treatment difference was observed for liver abscesses prevalence (TYL= 63% vs. IGY= 52%; P = 0.40) or severity (P = 0.23). There was a greater proportion of erythromycin-resistant Enterococcus growth for TYL than IGY (42.6 vs. 21.9%; P &amp;lt; 0.04). Specifically formulated IGY feed additives may be viable alternatives to antibiotics in the diets of feedlot cattle.

81 Evaluation of feeding immunoglobulin-Y to Holstein feeder cattle for the control of liver abscesses & reduction of macrolide-resistant bacteria dissemination

Abstract Despite the regular use of macrolide-antibiotics in the diets of feedlot cattle, liver abscesses persist representing a financial burden to both pre- and post-mortem sectors of the beef industry. Alternative strategies, which simultaneously address liver infections and reduce the dissemination of antibiotic-resistant bacteria, are needed. An immunoglobulin-Y (IGY) product, developed to target Fusobacterium necrophorum andTrueperella pyogenes, was evaluated for the control of liver abscesses and its effect on macrolide-resistant Enterococcus growth from feces. Sixty-four Holstein steers (Initial BW= 384±13.5kg) consuming a finishing diet (90% concentrate) for 188 d (Final BW= 660±42 kg) were used in a completely randomized design where treatments included: TYL (Tylosin phosphate fed at 90 mg/hd/day; n = 32) or IGY (fed at 2.5g/hd/day; n = 32). Feed intake was recorded daily and BW was recorded every 28 d until slaughter. After 150 d on treatment fecal samples were randomly obtained from each treatment group four times (n = 40) and cultured on bile-esculine agar enriched with 8 μg/mL of erythromycin. Continuous variables of feedlot growth performance, carcass data and bacterial growth were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effects of steer or sampling day, respectively. Ordinal carcass data was analyzed using the FREQ procedure of SAS observing the Cochran-Mantel-Haenszel value. Treatment did not affect DMI (P = 0.21), ADG (P = 0.50) or G:F (P = 0.36). Treatment neither affected hot carcass weight (P = 0.37) nor longissimus muscle area (P = 0.25). However, TYL resulted in greater back fat thickness than IGY (0.32 vs. 0.23 in.; P &amp;lt; 0.02) and consequently greater numerical yield grade (P &amp;lt; 0.02). Quality grade was not affected by treatment (P = 0.65). No treatment difference was observed for liver abscesses prevalence (TYL= 63% vs. IGY= 52%; P = 0.40) or severity (P = 0.23). There was a greater proportion of erythromycin-resistant Enterococcus growth for TYL than IGY (42.6 vs. 21.9%; P &amp;lt; 0.04). Specifically formulated IGY feed additives may be viable alternatives to antibiotics in the diets of feedlot cattle.

83 Evaluation of feeding immunoglobulin-Y to Holstein feeder cattle for the control of liver abscesses &amp; reduction of macrolide-resistant bacteria dissemination

Abstract Despite the regular use of macrolide-antibiotics in the diets of feedlot cattle, liver abscesses persist representing a financial burden to both pre- and post-mortem sectors of the beef industry. Alternative strategies, which simultaneously address liver infections and reduce the dissemination of antibiotic-resistant bacteria, are needed. An immunoglobulin-Y (IGY) product, developed to target Fusobacterium necrophorum and Trueperella pyogenes, was evaluated for the control of liver abscesses and its effect on macrolide-resistant Enterococcus growth from feces. Sixty-four Holstein steers (Initial BW= 384± 13.5kg) consuming a finishing diet (90% concentrate) for 188 days (Final BW= 660± 42 kg) were used in a completely randomized design where steer was experimental unit and treatments included: TYL (Tylosin phosphate fed at 90mg/hd/day; n = 32) or IGY (fed at 2.5g/hd/day; n= 32). Feed intake was recorded daily and BW was recorded every 28 days until slaughter. After 150 d on treatment fecal samples were randomly obtained from each treatment group four times (n = 40) and cultured on bile-esculine agar enriched with 8 μg/mL of erythromycin. Continuous variables of feedlot growth performance, carcass data and bacterial growth were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effects of steer or sampling day, respectively. Ordinal carcass data were analyzed using the FREQ procedure of SAS observing the Cochran-Mantel-Haenszel value. Treatment did not affect DMI (P= 0.21), ADG (P = 0.50) or G:F (P = 0.36). Treatment neither affected hot carcass weight (P = 0.37) nor longissimus muscle area (P = 0.25). However, TYL resulted in greater back fat thickness than IGY (0.32 vs. 0.23 in.; P &amp;lt; 0.02) and consequently greater numerical yield grade (P &amp;lt; 0.02). Quality grade was not affected by treatment (P = 0.65). No treatment difference was observed for liver abscesses prevalence (TYL=63% vs. IGY=52%; P = 0.40) or severity (P = 0.23). There was a greater proportion of erythromycin-resistant Enterococcus growth for TYL than IGY (42.6 vs. 21.9%; P &amp;lt; 0.04). Specifically formulated IGY feed additives may be viable alternatives to antibiotics in feedlot cattle diets.

Effect of inclusion rate of silage with or without alpha-amylase trait on finishing steer growth performance, carcass characteristics, and agronomic efficiency measures.

One hundred ninety-two Continental × British steers [initial body weight (BW) = 420 kg (standard deviation = 24.7)] were used in a randomized complete block design finishing study to evaluate the effects of feeding two types of silage germplasm at two inclusion rates. A 2 × 2 factorial arrangement of treatments was used with either a conventional hybrid (Golden Harvest G07B39-311A, Syngenta Seeds LLC, Minnetonka, MN; CON) or a hybrid with increased expression of alpha-amylase (Syngenta Enogen Feed corn, Golden Harvest E107B3-3011A-EVT5, Syngenta Seeds, LLC; ENO) fed at either 12% (12SIL) or 24% (24SIL) of diet dry matter. Steers were blocked by source and location (source 1: first three pen replicates, n = 10 steers per pen with a fourth pen replicate of six steers per pen; source 2: one pen replicate, n = 12 steers per pen) and assigned randomly within block to treatments, resulting in five pens and 48 steers per treatment. Steers were harvested after 126 (12SIL) or 140 (24SIL) days on feed (DOF). There were no silage hybrid by inclusion rate interactions detected for live growth performance (P ≥ 0.15). Silage hybrid did not affect average daily gain (ADG), gain-to-feed ratio (G:F), or final BW (FBW; P ≥ 0.35). Feeding 24% silage reduced ADG (P = 0.04) and increased G:F (P = 0.01) but increased FBW (P = 0.02) because of greater DOF compared with 12SIL. A hybrid by inclusion rate interaction was detected (P = 0.04) for calculated yield grade (YG) with steers fed 24SIL having increased YG within CON but not ENO. Hot carcass weight and rib fat were unaffected by silage hybrid (P ≥ 0.81) but were increased by feeding 24SIL (P = 0.03 and P = 0.02, respectively). Feeding increased amounts of silage increased beef produced per hectare (P = 0.05). Source of silage did not affect feedlot growth performance of cattle but, because of slight differences in estimated silage yield, conventional silage produced more kilograms of beef per hectare (P < 0.01). Feeding increased amounts of silage reduced G:F on both a live and carcass-adjusted basis but increased kilograms of beef produced per unit of land, which is paramount to cattle feeders who grow their own feedstuffs.

Flight speed as an indicator of Zebu cattle growth performance and suitability to the feedlot environment

Context Studies assessing the relationship between cattle reactivity and growth performance, as well as suitability to the feedlot, in Zebu cattle are limited. Based on previous studies using Bos Taurus cattle, it is expected that reactivity measured at weaning could be used as a predictor of feedlot performance, and that cattle with greater flight speed (FS) would have reduced average daily gain (ADG). Aims The aims of this study were to (1) determine if FS (m/s) measured before entry into the feedlot could be used as a predictor of cattle performance, (2) evaluate the consistency of FS over time, and (3) determine when FS should be measured to best predict animal suitability to the feedlot. Methods A total of 54 Nellore and 40 Guzerat calves were assessed by using FS, which was collected at the time of (FS0) and 1 week after weaning (FS1), as well as on Day 28 (FS28), 56 (FS56) and 168 (FS168) after entry into the feedlot, and a FS average was calculated using FS28, FS56 and FS168 (FS28–168). Performance using ADG (kg/calf.day) was calculated for each animal over three periods: ADG1–28, ADG28–168 and ADG1–168. Bunk attendance (min/calf.day) was recorded over a 173-day feeding period. Key results The ADG28–168 was reduced by 0.14 kg/calf.day for each unit increase in FS0 (P &amp;lt; 0.05). Both ADG28–168 and ADG1–168 were reduced by 0.02 kg/calf.day for each unit increase in FS1 (P ≤ 0.01), but neither FS0 nor FS1 was associated with ADG1–28 (P &amp;gt; 0.10). A significant increase was observed between FS1 and FS28 (P &amp;lt; 0.01), followed by a reduction in FS56 (P &amp;lt; 0.01) and FS168 (P &amp;lt; 0.01). Conclusion FS measured at or within 1 week of weaning has the potential to be used as an indicator of feedlot growth performance in Nellore and Guzerat cattle. Implications Although our results do not indicate the efficacy of FS as a predictor of early suitability of cattle to the feedlot, it does have the potential to support its recommendation as an indicator of overall feedlot growth performance in Nellore and Guzerat breeds.

PSXI-13 Effect of Lactobacillus spp. and Saccharomyces cerevisiae alone or in combination, on ruminal fermentation, total tract nutrient digestibility and performance of growing beef cattle

Abstract The study evaluated the effect of Saccharomyces cerevisiae alone or in combination with Lactobacillus spp. delivered through silages as a direct fed microbial (DFM) on the nutrient digestibility and performance of growing beef cattle. Chopped and kernel processed corn silage was treated with either distilled water (CON), or with (cfu g1 fresh forage) 1.1 × 105 of a Lactobacillius plantarum and Lactobacillus buchneri (LAB) mixture (INOC1), 1.0 × 104 S. cerevisiae strain 3 (INOC2), or 1.1 × 105 LAB + 1.0 × 104 S. cerevisiae strain 3 (INOC3) and ensiled in AgBags®. Eight ruminally cannulated beef heifers in a replicated 4 × 4 Latin square and 60 crossbred individually fed beef steers in a randomized complete block design were used for the metabolism and feedlot growth performance experiments, respectively. The treatments were four total mixed rations composed of 65.0% of one of the four corn silages, 17.0% barley grain, 13.0% canola meal and 5.0% vitamin-mineral supplement (dry matter (DM) basis) for both experiments. Data were analyzed using the MIXED procedure of SAS. The molar percentage of ruminal acetate in heifers fed INOC2 and INOC3 were lower (P &amp;lt; 0.01) than those fed CON. The DM (P = 0.03), organic matter (P = 0.02), acid (P = 0.03) and neutral detergent fiber (P = 0.03) digestibility of heifers fed INOC2 were higher than those fed CON. The DM intake as a % of body weight tended (P = 0.08) to be lower for steers fed INOC2, while the average daily gain was similar to those fed CON. There is potential for delivering S. cerevisiae through silage as DFM for improving ruminal fermentation, total tract nutrient digestibility and the growth performance of beef cattle.

The effects of varying implant programs on feedlot growth performance and carcass characteristics of Holstein steers.

The effects of varying implant programs on feedlot growth performance and carcass characteristics of Holstein steers.

Effect of Supplemental Calcium Levels on Feedlot Growth Performance and Dietary Net Energy Utilization during the Receiving Feeding Period of Calf-Fed Holstein Steers

Ninety-six calf-fed Holstein steer (127 kg) were used to evaluate the influence of supplemental dietary calcium (Ca) on growth-performance, and dietary net energy (NE) utilization during the initial 112-d of receiving period. Treatments consisted of steam flake corn-based growing-finishing diets supplemented with limestone to achieve 0.60%, 0.70%, 0.80%, or 0.90% dietary Ca (DM basis). Morbidity was low (6.3%) and it was not affected (P > 0.87) by dietary treatments. During the initial 84-d period (181 kg average BW), increasing dietary Ca did not influence (P > 0.10) DMI, ADG, gain efficiency or observed/expected DMI. Observed DMI was 19% greater than expected based on diet formulation and growth. Estimated metabolizable protein and methionine supply during the initial 84-d period averaged 92% and 79% of the required, respectively. The apparent decrease in efficiency of energy utilization in the present study is in close agreement with previous studies involving calf-fed Holstein steers in the early growing phase fed conventional growing-finishing diet that is otherwise deficient in metabolizable amino acids. Thus, it is considered that the anticipated growth-performance responses to dietary Ca treatments may have been masked by expected inefficiencies due to metabolizable amino acid deficiency. During the final 28-d period (256 kg of average BW), increasing supplemental Ca reduced feed intake (linear effect, P = 0.04) and enhanced gain efficiency (linear effect, P = 0.03). During this period, predicted ([1] Level 1) metabolizable protein and methionine supply were 110% and 94% of the required, respectively. Nevertheless, improvements in gain efficiency during the final 28-d period with increasing levels of supplemental Ca were not sufficient to influence (P > 0.10) overall 112-d growth-performance. It is concluded dietary Ca requirements of calf-fed Holstein steers during the initial 112-d feeding period appear to be secondary to deficiencies of conventional steam-flaked corn-based diets in meeting metabolizable amino acid requirements. However, when those requirements are met during the early growing phase, gain efficiency responses are optimized at approximately 0.90% dietary Ca.

222 Effect of corn stalk inclusion rate on performance and rumination behavior in beef steers

Abstract Coarse roughage, such as corn stalks, in feedlot diets aids in the formation of a fibrous mat within the rumen. The fibrous mat supports rumen health, buffers pH, and reduces acidosis risk in cattle consuming high-concentrate diets. Excess roughage can increase physical fill, thus lowering the animal’s ability to consume enough energy for efficient growth. The objective of this experiment was to quantify feedlot growth performance, rumination, ruminal pH and carcass quality and yield outcomes of cattle consuming a finishing diet with increasing levels of roughage. Fifty-one steers (initial BW = 295 + 11 kg) were randomly allocated to 1 of 3 dietary treatments; 5% (5CS; n = 18), 10% (10CS; n = 17), or 15% (15CS; n = 16) corn stalks (DM basis) in a steam-flaked-corn based finishing diet. Steers were fitted with a sensory collar that recorded rumination (min/d) and one-half of the steers (n = 27) received a rumen bolus that continuously monitored pH. The experiment was conducted using a randomized complete block design. Data were analyzed using a mixed model; treatment was a fixed effect and block was a random effect. As CS inclusion increased, we observed increased DM intake (P = 0.01; 7.7, 8.2, and 8.5 kg/d, respectively), decreased gain efficiency (P &lt; 0.01; 0.18, 0.16, and 0.14 kg/kg DM, respectively), and a tendency for decreased ADG (P = 0.09; 1.34, 1.33, and 1.22 kg/d, respectively). Ruminal pH was highest (P &lt; 0.01) for 15CS (6.28) and similar for 5CS and 10CS (6.10). Steers spent more time ruminating (P &lt; 0.01) when consuming the 10CS diet (361 min/d) and least with 5CS diet (279 min/d). Increasing CS to 15% decreased rib fat thickness (P = 0.01), decreased calculated YG (P = 0.02), and decreased marbling score (P &lt; 0.01) compared with the 5CS and 10CS treatments. Feeding excess corn stalks (≥ 15%) may prevent adequate energy intake, thus diminishing feedlot growth performance and carcass merit.

189 Comparison of growth-promoting implant regimens from calfhood to finishing in beef steers: finishing phase

Abstract The objective of this study was to compare growth-promoting implant regimens and their effect on growth performance and carcass traits. Crossbred beef steers (n = 106; body weight = 96 ± 3.9 kg; age = 74 ± 2.0 d) were blocked by parity of dam (≤ 2 or &gt; 2 parities), and stratified by birth weight, calf age, calf sire, cow body weight and body condition score then were assigned randomly to 1 of 4 treatments: 1) administered Ralgro at branding (D 0), Ralgro at weaning (D 156), and Revalor XS at feedlot processing (D 325; RALG), 2) administered Component E-C at branding, Component TE-G at weaning, and Revalor XS at feedlot processing (COMP), 3) no growth-promoting implant at branding, administered Revalor-G at weaning, and Revalor XS at feedlot processing (N-REV), or 4) no growth-promoting implants administered during any phase of production (CTRL). Quantitative data were analyzed using PROC MIXED, whereas qualitative data were analyzed using the PROC GLIMMIX of SAS. At the end of the stocker phase (d 323), RALG (330 kg), COMP (324 kg), and N-REV (318 kg) were heavier (P = 0.02) compared to CTRL (297 kg). Calves implanted at branding, weaning, and feedlot entry (RALG and COMP) were ≥ 87 kg heavier than CTRL and 17 kg heavier compared to calves implanted only at weaning and feedlot entry (N-REV). Overall ADG during the feedlot phase were greater (P &lt; 0.01) for RALG (2.17), COMP (2.17), and N-REV (2.09) compared to CTRL (1.76 kg). Hot carcass weights were greater (P &lt; 0.01) in implanted steers compared to CTRL; however, quality grade was not affected (P = 0.79) by growth-promoting implant regimen. Implanting steers at branding or weaning may not negatively affect feedlot growth performance or carcass traits.

Effects of a single initial and delayed release implant on arrival compared with a non-coated initial implant and a non-coated terminal implant in heifers fed across various days on feed.

Two experiments evaluated the effect of implant number, type, and total steroidal dose on live animal performance and carcass traits in heifers fed for three different days on feed (DOF). In experiment 1, heifers (n = 3,780; 70 heifers/pen and 9 pens/treatment; initial body weight [BW] = 309 kg) were used in a 2 × 3 factorial arrangement of treatments. Factors were as follows: 1) implant (all from Merck Animal Health, De Soto, KS): 200 mg trenbolone acetate (TBA) and 20 mg estradiol-17β (E2) administered on arrival (SINGLE), or 80 mg TBA and 8 mg E2 administered on arrival followed by 200 mg TBA and 20 mg E2 after approximately 90 d (REPEATED) and 2) duration of DOF: harvested after approximately 172, 193, and 214. In experiment 2, heifers (n = 3,719; 65 to 70 heifers/pen and 9 pens/treatment; initial BW = 337 kg) were used with the same factors as experiment 1, except DOF were 150, 171, and 192. No implant × DOF interaction (P ≥ 0.06) was noted for any performance parameters in either experiment. Heifers administered REPEATED had improved (P ≤ 0.05) live gain to feed ratio (G:F) and carcass-adjusted G:F and tended (P = 0.09) to have greater hot carcass weight (HCW) in experiment 1. Increasing DOF resulted in greater (P ≤ 0.01) live and carcass-adjusted final BW and decreased (P = 0.01) live ADG in experiment 1. As DOF increased, HCW, HCW gain, and dressing% (P ≤ 0.01) increased in experiment 1. The mean carcass transfer was 79.6% across the 42 d terminal window in experiment 1. In experiment 2, REPEATED had improved (P = 0.03) carcass-adjusted G:F compared with SINGLE, but HCW was not different (P = 0.36) between treatments. Increased DOF resulted in greater (P ≤ 0.01) final live and carcass-adjusted BW, decreased (P ≤ 0.01) live and carcass-adjusted ADG, and poorer (P ≤ 0.01) live and carcass-adjusted G:F in experiment 2. In experiment 2, dressing percentage was greater (P = 0.02) in REPEATED compared with SINGLE. Heifers given SINGLE had greater (P = 0.01) back fat and estimated empty body fat (EBF), whereas REPEATED had fewer (P = 0.01) Yield Grade 4 carcasses and greater (P = 0.01) longissimus muscle (LM) area. Increased DOF resulted in greater (P ≤ 0.04) HCW, HCW gain, dressing%, back fat, LM area, marbling, EBF%, and United States Department of Agriculture (USDA) Prime-grading carcasses, Yield Grade 4 and 5, and over 454-kg carcasses in experiment 2. Carcass ADG and carcass transfer indicate a 0.70 kg carcass ADG between 150 and 192 DOF, resulting in an average carcass transfer of 72.2% in experiment 2. Although feedlot growth performance and HCW did not differ between the implant regimens tested, increasing DOF resulted in decreased live growth performance while increasing the proportion of USDA prime carcasses and HCW.

Growing System Effects on Silage Type Selection for the Finishing Phase of Beef Steers: Feedlot Growth Performance, Carcass Characteristics, Nutrient Digestibility, and Feeding Behavior

Growing System Effects on Silage Type Selection for the Finishing Phase of Beef Steers: Feedlot Growth Performance, Carcass Characteristics, Nutrient Digestibility, and Feeding Behavior

Influence of level and form of supplemental zinc on feedlot growth performance and carcass characteristics of calf-fed Holstein steers

<h2>ABSTRACT</h2> The objectives of this study were to evaluate the influence of level and source of supplemental Zn on growth performance and dietary energetics in calf-fed Holstein steers. A total of 168 steers (BW = 133 ± 7 kg) were used in a 336-d study. Treatments consisted of diets based on steam-flaked corn supplemented with (DM basis) (1) 20 mg of Zn/kg of DM as ZnSO₄; (2) 10 mg of Zn/kg of DM as ZnSO₄ plus 10 mg of Zn/kg of DM as Zn betaine; (3) 20 mg of Zn/kg of DM as Zn betaine; or (4) 40 mg of Zn/kg of DM as ZnSO₄. Overall (d 1 to 336) there were no treatment effects (<i>P</i> > 0.10) on carcass-adjusted ADG, gain efficiency, and estimated dietary NE. At the 20 mg/kg level of Zn supplementation, the proportion of supplemental Zn provided as chelate did not influence overall ADG, gain efficiency, or dietary NE (<i>P</i> > 0.10). The proportion of Zn supplemented as chelate did not affect (<i>P</i> > 0.10) carcass weight, KPH, LM area, or marbling score. However, DP was greater (quadratic effect, <i>P</i> = 0.01) for steers receiving the 50:50 blend of ZnSO₄ and Zn betaine. Carcass yield grade improved (linear component, <i>P</i> = 0.03) with proportion of supplemental Zn as chelate. We conclude that at a 20 mg/kg (DM basis) level of supplementation, Zn source does not affect growth performance of calf-fed Holstein steers. Increasing level of Zn supplementation (as ZnSO₄) from 20 to 40 mg/kg will not further enhance overall performance responses.

335 Predicting feedlot growth performance over the feeding period using steer age and body weight

335 Predicting feedlot growth performance over the feeding period using steer age and body weight

Influence of flake density and tempering on the feeding value of steam-flaked corn for feedlot cattle

ABSTRACTA feedlot growth-performance trial was conducted to evaluate the relative response to tempering when flake density (FD) of corn is increased from 0.31 kg/L (24 lb/bushel) to 0.39 kg/L (30 lb/bushel). Treatments were (1) non-tempered, FD = 0.31 kg/L; (2) non-tempered, FD = 0.39 kg/L; (3) tempered, FD = 0.31 kg/L and (4) tempered, FD = 0.39 kg/L. Tempering prior to flaking increased (21%, P < .01) the moisture content of corn as it exited the rolls and decreased (14%, P = .02) the starch enzymatic reactivity. Increasing roll tension to reduce FD decreased flake thickness (24%, P < .01) and increased starch reactivity (43%, P < .01). Increasing FD decreased (P = .03) estimated dietary NEm and NEg, and the estimated NEm and NEg values of steam-flaked corn by 2.3% and 2.9%, respectively. We conclude that whereas tempering corn grain before steam flaking increases the moisture content of corn as it exits the roles, it has minimal influence on the feeding value for corn for feedlot cattle. Increasing FD from 0.31 to 0.39 kg/L decreases starch reactivity and the net energy value of corn, but does not affect daily weight gain or carcass characteristics.

Influence of protein nutrition and virginiamycin supplementation on feedlot growth performance and digestive function of calf-fed Holstein steers.

Two experiments were conducted to examine the influence of protein and virginiamycin (VM) supplementation on feedlot growth performance, digestion, and metabolizable AA (MAA) supply of calf-fed Holstein steers. Growth performance and dietary energetics were evaluated in 120 Holstein steers (127 ± 9 kg). During the initial 112-d feeding period, a steam-flaked corn-based diet was balanced to meet either 100% (MAB) or 87% (UREA) of MAA requirements. Diets were supplemented with or without 22.5 mg/kg VM in a 2 × 2 factorial arrangement. Subsequently (d 112 to 308), all steers received the UREA diet with or without VM. During the initial 112-d, MAB increased ADG, G:F, and dietary NE ( < 0.01). Thereafter, when all steers received the UREA diet, ADG, G:F, and dietary NE were not different ( > 0.10) across initial supplementation treatments. Overall (d 1 to 308), MAB did not affect ADG ( > 0.10) but enhanced G:F efficiency ( = 0.03) and dietary NE ( = 0.05). During the initial 112-d period and through the remainder of the experiment, VM increased G:F ( < 0.01) and dietary NE ( < 0.01). Four Holstein steers (146 ± 4 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square design to evaluate initial 112-d treatment effects on digestive function. There were no treatment effects ( > 0.10) on ruminal digestion of OM, NDF, starch, microbial efficiency, or total tract digestion of OM and NDF. The MAB increased indispensable AA flow to the small intestine ( < 0.01) and total tract digestion of N ( < 0.01) and starch ( = 0.04). Observed AA supply to small intestine was in agreement with expected supply ( = 0.96). Virginiamycin decreased ( = 0.04) nonammonia N flow to the small intestine and did not affect ( > 0.10) total tract N digestion. Extrapolating from AA supplies in the metabolism study, MAB satisfied indispensable AA requirements during the initial 112-d period, whereas the UREA diet met 73.5% and 79.2% of methionine and lysine requirements, respectively. During the subsequent periods (d 112 to 308) indispensable AA supplies exceeded theoretical requirements. We conclude that enhancements in energy utilization when diets are balanced to meet MAA requirements of calf-fed Holstein steers during the initial 112-d feedlot period remain appreciable throughout time on feed. Virginiamycin enhanced efficiency of energy utilization throughout the feedlot growing-finishing period.