158 Effect of Mootral™ and Forage Amount on Methane Emissions, Growth and Carcass Characteristics of Feedlot Steers

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 123-124
Author(s):  
Bryce Bitsie ◽  
Andrea M Osorio ◽  
Darren D Henry ◽  
Breno Silva ◽  
Leticia Godoi ◽  
...  
Keyword(s):  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Methane Emissions ◽  
Feedlot Cattle ◽  
Corn Silage ◽  
Feed Ratio ◽  
Feedlot Steers ◽  
Fat Thickness ◽  
Citrus Extract ◽  
Daily Gain

Abstract One hundred and forty-four Angus x Simmental steers were allotted by body weight (BW; 363 kg, breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different diets (forage content of 15, 41.5, or 68% corn silage). From day 85 to slaughter, corn silage was included at only 15% of the diet DM. Data were analyzed using the MIXED procedure of SAS. There was an interaction (P = 0.03) between forage content and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage, but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (P ≥ 0.22) of forage content or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. Gain-feed ratio from d 0 to 84 and overall was greater (P = 0.04) for steers fed 68% compared to 15 or 41.5% corn silage. On d 41, steers fed 41.5 and 68% corn silage had increased (P ≤ 0.02) methane emissions compared to steers fed 15% corn silage. There tended to be an interaction (P ≤ 0.09) between forage content and Mootral for methane emissions (g/d) on d 41 and 203, where steers fed Mootral showed lesser methane emissions with 15% corn silage, but not with the 41.5 and 68% corn silage diets. Steers fed Mootral showed lesser (P ≤ 0.03) methane emissions on d 203. Mootral tended to decrease (P < 0.10) fat thickness and yield grade. In conclusion, Mootral decreased methane production in 15% corn silage diets and improved carcass leanness.

scholarly journals Triticale silage replaces sorghum silage in finishing of Braford heifers

2021 ◽  
Vol 73 (5) ◽  
pp. 1180-1186
Author(s):  
A.M. Oliveira ◽  
L.D.F. Silva ◽  
A.P.O. Souza ◽  
E.L.A. Ribeiro ◽  
C.C. Jobim ◽  
...  
Keyword(s):  
Feed Intake ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Live Weight ◽  
Feed Ratio ◽  
Beef Heifers ◽  
Fat Thickness ◽  
Sorghum Silage ◽  
Experimental Treatments ◽  
Daily Gain

ABSTRACT The aim of this study was to evaluate the effect of sorghum silage substitution with different proportions of triticale silage on the performance and carcass of Braford heifers. Twenty-four Braford heifers were randomly assigned to four diets where sorghum silage was replaced at 0%, 30%, 60%, and 100% for triticale silage in a feedlot system. During sixty-tree days of the experiment, the feed intake, feed ratio conversion, and average daily gain were measured. The heifers were slaughtered and the effects of the sorghum and triticale silage in carcass characteristics were evaluated. The replacement of sorghum silage with triticale silage did not affect the feed intake and average daily gain (P> 0.05). Feed gain ratio was higher for the heifers that received lower proportions of triticale silage (0% and 30%) in replace sorghum silage (P <0.05). Eye loin area and fat thickness were similar among treatments (P<0.05). Other carcass characteristics, such as slaughter live weight, dressing percentage, conformation and fat classification were similar among experimental treatments (P<0.005). Triticale silage can replace sorghum silage for finishing beef heifers in feedlot system and provides similar carcass characteristics.

scholarly journals 401 Effect of zinc source and ractopamine hydrochloride on the growth performance and carcass characteristics of steers fed in confinement to harvest

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 160-160
Author(s):  
John Wagner ◽  
William T Nelson ◽  
Terry Engle ◽  
Jerry Spears ◽  
Jeff Heldt ◽  
...  
Keyword(s):  
Feed Efficiency ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Feedlot Cattle ◽  
Beef Steers ◽  
Live Animal ◽  
Zinc Source ◽  
Dressing Percentage ◽  
Ractopamine Hydrochloride ◽  
Daily Gain

Abstract Four hundred and thirty-two beef steers (346.3 ± 63.7 kg BW) were used to determine the effects of Zn source on feedlot cattle fed ractopamine hydrochloride. Cattle were blocked in groups of 54 by BW and housed in 48 pens containing 9 steers per pen. Pens within a weight block were randomly assigned to treatments in a 2 x 3 factorial arrangement, with factors being: 1) 0 or 30.1 mg of ractopamine HCl/kg DM fed during the final 29 days on feed; and 2) Zn source: 90 mg of supplemental Zn/kg DM from ZnSO4; Zn sulfate (67%) + Zn methionine (33%); and Zn from Zn hydroxychloride, fed through the entire feeding period. Cattle were fed a high concentrate finishing diet for 154 d and slaughtered at a commercial abattoir. Average daily gain, DMI, feed efficiency and carcass characteristics were determined after slaughter. Zinc source had no impact on live animal performance. Cattle fed ractopamine HCl had greater (P &lt; 0.01) final BW, greater (P &lt; 0.001) ADG, improved (P &lt; 0.001) G:F, heavier (P &lt; 0.01) HCW, and larger (P &lt; 0.05) longissimus muscle compared to non-ractopamine supplemented steers. There was a Zn source by ractopamine interaction (P &lt; 0.01) for dressing percentage. Cattle receiving ractopamine HCl with Zn hydroxychloride had a greater dressing percentage (P &lt; 0.05) when compared to ractopamine HCl cattle fed other Zn sources. Cattle receiving ractopamine HCl with Zn sulfate had a lesser dressing percentage (P &lt; 0.05) when compared to ractopamine HCl cattle fed other Zn sources. Additional Zn source by ractopamine HCl interactions were not significant. These data indicate that Zn source has minimal impacts on feedlot steer performance and carcass characteristics when supplemented to cattle receiving 0.0 or 30.1 mg of ractopamine HCl/kg DM.

scholarly journals Effects of coated and noncoated steroidal implants on growth performance, carcass characteristics, and serum estradiol-17β concentrations of finishing Holstein steers

2020 ◽  
Vol 4 (4) ◽  
Author(s):  
Pedro H V Carvalho ◽  
Mariana F Westphalen ◽  
Jonathan A Campbell ◽  
Tara L Felix
Keyword(s):  
Growth Performance ◽  
Animal Health ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Feed Ratio ◽  
Serum Estradiol ◽  
Trenbolone Acetate ◽  
Coated Implant ◽  
Daily Gain ◽  
Estradiol 17Β

Abstract The objectives of the study were to determine the effect of coated or noncoated hormone implants on growth performance, carcass characteristics, and serum estradiol-17β (E2) concentrations of Holstein steers fed a grain-based diet for 112 d. Seventy-nine Holstein steers [average initial body weight (BW) = 452 ± 5.5 kg] were stratified by BW and allotted to one of two treatments: 1) Holstein steers implanted with a coated implant containing 200 mg of trenbolone acetate (TBA) and 40 mg E2 (Revalor-XS (Merck Animal Health; Summit, NJ)] on day 0 (XS) or 2) Holstein steers implanted two times (days 0 and 56) with a noncoated implant containing 80 mg of TBA and 16 mg of E2 [(2IS) Revalor-IS (Merck Animal Health)]. Data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC). There was no effect (P ≥ 0.71) of implant strategy on initial, middle, and final BW. No effect (P ≥ 0.12) of implant strategy was observed on average daily gain, dry matter intake, or gain-to-feed ratio. There were no effects (P ≥ 0.11) of implant strategy on carcass characteristics. There was an implant × day interaction (P &lt; 0.01) for the circulation of serum E2 concentrations. Serum E2 concentration increased similarly 14 d after Holstein steers were implanted, regardless of implant strategy. At 28 d, after steers were implanted, steers in the XS group had less serum E2 concentration than Holstein steers in the 2IS group. However, at 56 d after the first implantation, both groups, once again, had similar serum E2 concentrations and E2 concentrations were less on day 56 than day 28 for both strategies. Holstein steers implanted with 2IS had greater serum E2 concentration on day 70 and E2 concentrations remained greater than serum E2 of Holstein steers implanted XS for the duration of the trial (day 112). In summary, there was no effect of coated or two doses of noncoated implant on growth performance or carcass characteristics of Holstein steers.

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

2019 ◽  
Vol 4 (1) ◽  
pp. 206-213 ◽  
Author(s):  
Pedro Henrique Vilela Carvalho ◽  
George A Perry ◽  
Tara L Felix
Keyword(s):  
Feed Efficiency ◽  
Animal Health ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Feed Ratio ◽  
Longissimus Muscle ◽  
Feedlot Performance ◽  
Trenbolone Acetate ◽  
Daily Gain ◽  
Estradiol 17Β

Abstract The objectives of the study were to determine the effect of steroidal implants on growth performance, carcass characteristics, and estradiol-17β (E2) concentrations in the blood and longissimus muscle of Holstein steers fed a grain-based diet. Seventy Holstein steers (average initial BW = 275 ± 6.4 kg, 10 to 12 mo of age) were assigned to treatments: (i) implanted with 80 mg of trenbolone acetate (TBA) and 16 mg of E2 (Component TE-IS with Tylan; Elanco Animal Health, Greenfield, IN) at the start of the trial (day 0), and reimplanted with 120 mg of TBA and 24 mg of E2 (Component TE-S with Tylan; Elanco Animal Health) on day 84 of the experiment; or (ii) no implant. Implanted Holstein steers were heavier (P ≤ 0.01) than nonimplanted Holstein steers in the middle (day 84) and at the end of the experiment (day 186). Implanting Holstein steers increased (P &lt; 0.01) average daily gain (ADG) and dry matter intake (DMI) without affecting gain-to-feed ratio compared with nonimplanted animals. Carcasses from implanted Holstein steers had greater (P &lt; 0.01) hot carcass weight (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 in implanted Holstein steers compared with that from nonimplanted Holstein steers. There was an implant × day interaction (P &lt; 0.01) in serum E2 concentrations. Serum E2 concentrations were not altered in nonimplanted Holstein steers, whereas E2 concentration increased (P &lt; 0.01) after steers were implanted, regardless of implant characteristics. Serum E2 peaked at 28 days after the first implant and then rapidly declined after day 56. In summary, steroidal implants administered on days 0 and 84 increased DMI, ADG, HCW, and LM area in Holstein steers compared with nonimplanted steers due to increased serum E2 concentrations. However, these changes did not improve feed efficiency or other carcass characteristics.

INFLUENCE OF HIGH-MOISTURE BARLEY ON THE PERFORMANCE AND CARCASS CHARACTERISTICS OF FEEDLOT CATTLE

1988 ◽  
Vol 68 (3) ◽  
pp. 811-820 ◽  
Author(s):  
J. J. KENNELLY ◽  
G. W. MATHISON ◽  
G. de BOER
Keyword(s):  
Dry Matter ◽  
Free Choice ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Barley Grain ◽  
Feedlot Cattle ◽  
Feed Conversion ◽  
High Moisture ◽  
Feeding Value ◽  
Daily Gain

Three factorial experiments were conducted to determine the relative feeding value of dry barley (DB) and high-moisture barley (HMB), and to evaluate the influence of method of ensiling (Pit vs. Harvestore® (HAV) silo), source of roughage (hay vs. silage), and level of concentrate (90 vs. 75%) on the performance and carcass characteristics of feedlot cattle. In exp. 1, 252 steers (initial wt 357 kg) were assigned on the basis of weight to six treatments (two pens × 21 animals per pen). A mixed diet consisting of 85.2% barley grain (dry matter (DM) basis) was offered free choice. The barley portion of the ration consisted of either 0, 25, 50, 75 or 100% DB with the balance being HMB from a pit silo. The sixth treatment consisted of feeding 100% HMB for the first 57 d and 100% DB for the remainder of the trial. Overall average daily gain (ADG) for steers fed 100% DB (1.70 kg d−1) was significantly higher than observed for animals fed 100, 75 or 50% HMB (1.46, 1.49 and 1.56 kg d−1, respectively). The kg of feed DM required per kg gain (FC) varied between 5.76 and 7.13 and was not (P > 0.05) influenced by treatment. No differences (P > 0.05) were observed in carcass characteristics. In exp. 2, 360 steers (initial wt 340 kg) were allotted on the basis of weight to six treatments designed to evaluate the effect of source (Pit vs. HAV) and level of HMB, in diets containing 10.2% silage, on animal performance. Overall ADG (1.11 – 1.17 kg d−1), FC (6.66 – 7.01) and carcass characteristics were similar (P > 0.05) for animals fed Pit HMB, HAV HMB and DB. In exp. 3, 264 weanling calves (initial wt 216 kg) were allotted on the basis of weight to six treatments which differed in type of barley (HMB vs. DB), source of roughage (hay vs. silage) and level of concentrate (75 vs. 90%; DM basis). The feeding period was 127 d. Daily gains varied between 0.78 and 0.91 kg d−1 and FC ranged from 6.40 to 7.10 and were not influenced (P > 0.05) by source of barley or source or level of roughage. While animals fed DB had significantly higher ADG than those fed HMB in exp. 1, the overall results from the three experiments indicate that on a DM basis HMB has similar feeding value to DB, and that there is no major difference between Pit and HAV-stored HMB for feedlot cattle. Key words: High moisture, barley, cattle, gain, feed conversion

scholarly journals Effects of increasing dietary level of a commercial liquid supplement on growth performance and carcass characteristics in feedlot steers

2018 ◽  
Vol 2 (2) ◽  
pp. 216-222
Author(s):  
Tara L Felix ◽  
Chloe J Long ◽  
Madeline R Stierwalt ◽  
Pedro H V Carvalho ◽  
Howard M Blalock
Keyword(s):  
Growth Performance ◽  
Block Design ◽  
Carcass Characteristics ◽  
Feedlot Cattle ◽  
Corn Silage ◽  
Distillers Grains ◽  
Dietary Level ◽  
Distillers Grains With Solubles ◽  
Feedlot Steers ◽  
Randomized Complete Block Design

Abstract Feeding cattle liquid supplements has become increasingly popular in the feedlot industry; however, optimal inclusion of liquid supplements in feedlot cattle diets is not known. The objectives of this study were to determine the optimal inclusion of liquid supplementation to maximize growth performance and improve carcass characteristics, as well as estimate the energy value of liquid supplementation when used as a direct corn replacement, for feedlot steers fed a concentrate-based diet. Two hundred and eighty steer calves were stratified by BW into light (BW = 208 ± 9 kg; n = 24) and heavy (BW = 275 ± 8 kg; n = 16) pens. Pens within BW block were randomly assigned to 1 of 4 supplements: 1) dry at 4.5% inclusion (0LIQ), 2) liquid (a proprietary blend from Quality Liquid Feeds; Dodgeville, WI) at 4.5% inclusion (4.5LIQ), 3) liquid at 9% inclusion (9LIQ), or 4) liquid at 13.5% inclusion (13.5LIQ). The remainder of the diet was 47.5% to 55.5% dry rolled corn, 20% corn silage, and 20% modified wet distillers grains with solubles (DM basis). Data were analyzed as a randomized complete block design and linear and quadratic were examined to determine effects of increasing dietary concentrations of liquid. Steers fed 4.5LIQ and 9LIQ had greater (quadratic; P ≤ 0.05) final BW, HCW, and NEm and NEg, and less DMI as a percent of BW compared to steers fed 13.5LIQ. Steers fed 0LIQ were intermediate and not different from other treatments. However, ADG and total BW gain did not differ (P ≥ 0.15) among treatments. Despite the lack of treatment effect on live measures of gain, feeding steers 4.5LIQ and 9LIQ resulted in greater carcass ADG (quadratic; P = 0.03), total carcass gain (quadratic; P = 0.04), and more efficient carcass gain (quadratic; P ≤ 0.01) compared to carcasses from steers fed 13.5LIQ. Feeding steers a liquid supplement at 9% of the diet, DM allowed for the greatest final BW and ADG in this study; however, there was no benefit of increasing liquid to 13.5%.

scholarly journals 340 Impact of essential oils blend on beef cattle performance and carcass characteristics in diets with increasing corn silage inclusions

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 138-139
Author(s):  
Hannah C Wilson ◽  
Henry Hilscher ◽  
Zachary E Carlson ◽  
Bradley M Boyd ◽  
Andrea K Watson ◽  
...  
Keyword(s):  
Body Weight ◽  
Essential Oils ◽  
Dry Matter ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Corn Silage ◽  
Feed Ratio ◽  
Animal Performance ◽  
Final Body Weight ◽  
Significant Difference

Abstract A feedlot study was conducted comparing a natural feed additive (essential oils blend) at varying silage inclusions on receiving and finishing performance. The study utilized 480 crossbred steers (initial shrunk BW 296 kg ± 7.72 kg) in 48 pens with 10 steers/pen and 8 pens per treatment. Treatments were designed as a 2 × 3 factorial with 3 inclusions of corn silage [14, 47, 80 %; dry matter (DM) basis] with or without (+, -) the inclusion of an essential oils (EO) blend. All treatment diets contained 16% modified distillers grains plus solubles and 4% supplement with dry-rolled corn replacing corn silage (CS) on a DM basis. Steers were fed at 80% CS inclusion and adapted to 47% and 14% CS over a 10 and 24-d period, respectively. Cattle fed 80% CS were fed for 238 days, 47% CS for 195 days, and 14% CS were fed for 168 days to a common backfat of 1.28 cm (P > 0.59). There were no interactions for corn silage inclusion and the inclusion of essential oils on final body weight (FBW), dry matter intake (DMI), average daily gain (ADG), gain to feed ratio (G:F), hot carcass weight (HCW), longissimus muscle (LM) area, marbling, or calculated yield grade (CYG; P > 0.15). There was no significant difference for FBW, DMI, ADG, G:F, HCW, LM area, marbling, or CYG for cattle fed EO or no EO. However, there was a quadratic response for FBW, ADG, G:F, HCW, marbling and CYG with increased inclusion of corn silage (P < 0.04). Feeding corn silage at greater inclusions decreased animal performance but increased final body weight when fed to an equal fatness. Essential oils did not affect animal performance or carcass characteristics. However, feeding greater amounts of corn silage can be an economical way to finish cattle.

scholarly journals Effect of protein source and non-roughage NDF content in finishing diets of feedlot cattle fed free-choice hay on growth performance and carcass characteristics

2021 ◽  
Author(s):  
Alejandro M Pittaluga ◽  
Chris Clark ◽  
Alejandro E Relling
Keyword(s):  
Growth Performance ◽  
Soybean Meal ◽  
Protein Intake ◽  
Free Choice ◽  
Carcass Characteristics ◽  
Feedlot Cattle ◽  
Protein Source ◽  
Feed Ratio ◽  
Finishing Diets ◽  
Fat Thickness

Abstract One-hundred twenty crossbreed steers (initial body weight (BW) 566 ± 42 kg) were used to evaluate the interaction of protein source (PS) and non-roughage NDF content (NRFC) in finishing diets of feedlot cattle fed free-choice hay on performance and carcass characteristics. Steers were stratified by BW and randomly assigned to 8 pens (2×2 factorial) and fed for 104 ± 10 d. Four dietary treatments were investigated: 1) distillers’ dry grains with solubles (DDGS) and a low NRFC (DLF), 2) DDGS and a high NRFC (DHF), 3) soybean meal (SBM) and a low NRFC (SLF), 4) SBM and a high NRFC (SHF). Free-choice grass hay and concentrates were offered in a different bunk. Data were analyzed as a randomized complete block design. Do to the confounded effect of PS and protein intake, a linear regression was used to evaluate the effect of protein intake in growth performance. For gain to feed ratio (G:F) an interaction tended to occur (P = 0.10) between PS and NRFC. Steers on the DHF treatment had a lower G:F compared with SLF and SHF. Feeding SBM increased (P = 0.05) final BW, tended to increase (P = 0.06) average daily gain (ADG), and decreased (P = 0.05) hay intake (HI) compared with steers fed DDGS. There was a positive association (P ˂ 0.01) of crude protein intake with ADG and FBW. Dietary NRFC did not change (P ≥ 0.3) final BW, ADG, DMI, and HI. Protein source did not affect (P ≥ 0.16) hot carcass weight (HCW), longissimus muscle (LM) area, dressing, 12th rib fat thickness, or marbling score (MS). No differences were detected between NRFC for dressing, HCW, LM area, or MS (P ≥ 0.18); but diets with greater NRFC decreased (P = 0.03) the 12th rib fat thickness. Steers in the SHF treatment presented the lesser kidney-pelvic-heart fat compared with the remaining treatments (PS×NRFC interaction, P = 0.04). Soybean meal inclusion/increase in protein intake improved growth performance of feedlot steers compared with DDGS, despite protein intake meet the protein requirement. Increasing the NRFC did not affect growth or HI but decreased feed efficiency of steers fed DDGS.

scholarly journals 33 Determining the feeding value of hulless barley relative to corn in beef finishing rations

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 47-47
Author(s):  
Gabriel J Pent ◽  
Thomas B Wilson
Keyword(s):  
Body Weight ◽  
Dry Matter ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
The Other ◽  
Hulless Barley ◽  
Feeding Value ◽  
Fat Thickness ◽  
Ad Libitum ◽  
Daily Gain

Abstract Hulless varieties of barley have been developed to improve the digestibility of this small grain. The objective of this project was to determine the feeding value of hulless barley relative to corn in a beef-finishing ration. Angus-cross steers (n = 12) were fed rations that included varying ratios of cracked corn and cracked hulless barley. Steers were stratified by body weight (BW) and allotted to one of four rations: corn, 2:1 ratio of corn to barley, 1:2 ratio of corn to barley, and barley. All treatments included concentrate at 85% and baleage at 15% of total ration dry matter (DM). Rations were fed ad libitum on an individual basis using Calan gates. Feed refusals were measured daily. Steers were weighed and ultrasound 12th rib fat thickness (FT) was measured every 28 d. Steers were harvested at a commercial abattoir when average FT exceeded 0.9 cm. Average daily gain (1.2 kg/d), final BW (653 kg), feed to gain efficiency (10.2:1), and final ultrasound FT (0.94 cm) were not different (P ≥ 0.1486) between treatments. Steer DM intake was lower (P ≤ 0.0496) for those fed corn (9.8 kg/d) compared to those fed barley (12.2 kg/d) or a 1:2 ratio of corn to barley (11.7 kg/d); steer DM intake was similar (P ≥ 0.0640) for those fed a 2:1 ratio of corn to barley compared to those fed the other rations. Finishing ration did not affect hot carcass weight (384 kg; P = 0.7158), carcass FT (1.6 cm; P = 0.9511), ribeye area (87.7 cm^2; P = 0.7184), kidney, pelvic, and heart fat (2.6%; P = 0.3842), and yield grade (3.5; P= 0.8802). Feeding hulless barley compared to corn resulted in similar performance and carcass characteristics when included in beef finishing rations although feed intake was greater when barley exceeded 56% of the ration DM.

scholarly journals Growth, performance, and carcass characteristics of feedlot Holstein steers fed ractopamine hydrochloride1

2019 ◽  
Vol 4 (1) ◽  
pp. 102-117
Author(s):  
Cathy L Lockard ◽  
Chris J Richards ◽  
Caleb G Lockard ◽  
Maggie Youngers ◽  
Mariah A Woolsoncroft ◽  
...  
Keyword(s):  
Block Design ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Carcass Weight ◽  
Feed Ratio ◽  
Negative Effects ◽  
Feedlot Performance ◽  
Randomized Complete Block Design ◽  
Growth Promoting ◽  
Daily Gain

Abstract Growth-promoting technologies such as implants, ionophores, and β-agonists improve feedlot performance, efficiency, and carcass characteristics of cattle. The objective of this experiment was to determine the effects of dose and duration of ractopamine hydrochloride (RH) on feedlot performance and carcass characteristics when fed to Holstein steers. A randomized complete block design was used with a 3 × 3 factorial arrangement of treatments with 3 RH doses (0, 300, or 400 mg∙steer−1∙d−1) fed for 3 durations (28, 35, or 42 d). Holstein steers (n = 855; initial body weight [BW] = 448 ± 37 kg) were blocked by BW and randomly allocated to 1 of 9 pens (15 blocks; 9 dose × duration treatment combinations) approximately 72 d before harvest. Weekly pen weights, chute temperament scores, and animal mobility were determined during the RH feeding period. At harvest, carcass data were collected on all steers, and tenderness was measured on steaks from 3 or 4 randomly selected steers from each pen and slice shear force (SSF) was determined on one steak selected from each side of the carcass after aging for 14 or 21 d. For feedlot performance, carcass characteristics, and SSF, no dose × duration interactions were observed (P ≥ 0.11). With increasing RH dose, average daily gain (ADG) and gain-to-feed ratio (G:F) increased linearly (P ≤ 0.01), whereas BW gain increased linearly with RH dose and duration (P ≤ 0.01). Hot carcass weight (P = 0.02) and longissimus muscle (LM) area (P ≤ 0.01) increased linearly with increasing RH dose. The percentage of carcasses in the USDA Yield Grade 2 category increased linearly (P ≤ 0.01) and percentage of carcasses in the USDA Yield Grade 4 category tended (P = 0.08) to decrease linearly as RH dose increased. In the 14-d aged steaks, the percentage of steaks with SSF ≤ 15.3 kg decreased linearly (P ≤ 0.01), whereas the percentage of steaks with ≥20.0 kg SSF increased linearly (P ≤ 0.01) with increasing RH dose. After 21-d aging, there was a tendency (P = 0.06) for a greater percentage of steaks from steers fed RH to have SSF ≥ 20.0 kg (2% of total steaks), but no difference (P ≥ 0.12) in the percentage of steaks with SSF ≤ 19.9 kg. Final chute temperament (P ≥ 0.45) and animal mobility (P ≥ 0.67) scores were not affected by feeding RH. Increasing the dose of RH (300 or 400 mg∙steer−1∙d−1) fed for 28 to 42 d before harvest increased ADG, G:F, hot carcass weight, and LM area when fed to Holstein steers with no negative effects on behavior or mobility. The percentage of steaks classified as not tender improved when steaks were aged for 21 d from steers treated with RH.

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