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

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

Translational Animal Science ◽

10.1093/tas/txz186 ◽

2019 ◽

Vol 4 (1) ◽

pp. 206-213 ◽

Cited By ~ 1

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 < 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 < 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 < 0.01) in serum E2 concentrations. Serum E2 concentrations were not altered in nonimplanted Holstein steers, whereas E2 concentration increased (P < 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.

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274 Effects of Revalor ih/revalor-200 Re-implant Program or Revalor-xh on Performance and Carcass Characteristics of Finishing Heifers Fed for 179, 200, or 221 Days

Journal of Animal Science ◽

10.1093/jas/skab054.219 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 130-131

Author(s):

Brandon L Nuttelman ◽

John P Hutcheson ◽

Wade T Nichols ◽

Marshall N Streeter ◽

Grant I Crawford ◽

...

Keyword(s):

Growth Performance ◽

Block Design ◽

Carcass Traits ◽

Carcass Characteristics ◽

Carcass Weight ◽

Beef Heifers ◽

Feedlot Performance ◽

Randomized Complete Block Design

Abstract The objective of this study was to compare feedlot performance and carcass traits between two implant programs in heifers harvested at 3 different days on feed (DOF; 179, 200, or 221 d). Crossbred beef heifers (n = 3,084; 291 + 3.9 kg) were used in a 2×3 factorial arrangement of treatments in a randomized complete block design. Revalor-IH (80 mg TBA and 8 mg E2) was administered on arrival followed by Revalor-200 (200 mg TBA and 20 mg E2) 94 d before harvest (IH/200) or Revalor-XH (80 mg TBA and 8 mg E2, uncoated; 120 mg TBA and 12 mg E2, coated) was administered on arrival (XH). No implant × DOF interaction was detected (P ≥ 0.09) for any parameter. Heifers subjected to IH/200 had greater (P ≤ 0.01) final BW, ADG (P < 0.01) and G:F (P = 0.01). As DOF increased, BW increased (P ≤ 0.01) while ADG (P<0.01) and G:F (P ≤ 0.01) decreased. Hot carcass weight was greater (P = 0.01) for IH/200 compared with XH (367 vs. 361 kg, respectively). Heifers receiving XH had greater marbling scores (P = 0.02; 582 vs. 568) and BF (P = 0.01; 1.78 vs 1.70 cm) compared with IH/200 while re-implanted heifers had increased (P = 0.01) REA (86.5 vs. 83.2 cm2). Heifers implanted with XH tended to be fatter than those implanted with IH/200 having a greater (P = 0.01) proportion of USDA Prime and fewer (P<0.01) USDA Select. Increasing DOF increased (P ≤ 0.03) HCW, DP, BF, REA, marbling, and proportion of USDA Prime carcasses. Growth performance and HCW were increased for IH/200 compared with XH heifers. Increasing DOF resulted in poorer ADG and G:F but increased HCW.

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Feedlot performance, carcass characteristics and meat quality of Zebu heifers supplemented with two β-adrenergic agonists

Animal Production Science ◽

10.1071/an15369 ◽

2017 ◽

Vol 57 (10) ◽

pp. 2125 ◽

Cited By ~ 1

Author(s):

F. J. Meraz-Murillo ◽

L. Avendaño-Reyes ◽

C. Pérez-Linares ◽

F. Figueroa-Saavedra ◽

V. Torres-Rodríguez ◽

...

Keyword(s):

Meat Quality ◽

Block Design ◽

Average Daily Gain ◽

Bos Indicus ◽

Carcass Characteristics ◽

Feed Ratio ◽

Meat Tenderness ◽

Adrenergic Agonists ◽

Feedlot Performance ◽

Meat Colour

The aim was to evaluate effects of administration of two β-adrenergic agonists (β-AA) on growth performance, carcass characteristics and meat-quality traits of Zebu heifers finished in a feedlot. Fifty-four Zebu heifers weighing 397 ± 29.1 kg were used in a randomised complete block design with three treatments and six blocks (i.e. 18 pens with 3 heifers per pen). Treatments were as follows: (1) control (C; no supplement); (2) zilpaterol hydrochloride (ZH; 60 mg per heifer per day); and (3) ractopamine hydrochloride (RH; 300 mg per heifer per day). The β-AA were added to the diets during the final 33 days of the finishing period, after which the heifers were immediately slaughtered. Relative to C, average daily gain and gain : feed ratio were improved (P < 0.05) in heifers supplemented with ZH, but not in those supplemented with RH. Feed intake in C heifers was lower (P < 0.05) than in ZH heifers, but similar (P > 0.05) to RH heifers. The hot carcass weight showed a trend to be heavier (P = 0.096) in ZH than in C heifers. However, Longissimus dorsi (LM) area was increased (P < 0.05) by ZH (73.94 cm2), but RH (70.45 cm2) and C (66.3 cm2) groups had a similar (P > 0.05) LM area. The meat from the ZH- and RH-supplemented heifers had higher Warner–Bratzler shear-force values (P < 0.01) than that from C heifers (ZH = 5.11; RH = 5.50; C = 4.89 kg/cm2), and the meat from RH-supplemented heifers was classified as ‘tough’. Variables associated with meat colour indicated that ZH led to a lower b* average, which was related to a lighter LM area than in C. In general, feedlot performance was enhanced only by the β-AA ZH, with meat tenderness from RH heifers classified as ‘tough’. Meat colour was not altered by β-AA supplementation. These data suggested that while ZH supplementation to Bos indicus heifers offered advantages in feedlot performance and some carcass traits, RH supplementation did not positively affect these biological responses.

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Effect of Zilpaterol Hydrochloride on Performance and Meat Quality in Finishing Lambs

Agriculture ◽

10.3390/agriculture10060241 ◽

2020 ◽

Vol 10 (6) ◽

pp. 241

Author(s):

Jorge Adalberto Cayetano-De-Jesus ◽

Rolando Rojo-Rubio ◽

Alicia Grajales-Lagunes ◽

Leonel Avendaño-Reyes ◽

Ulises Macias-Cruz ◽

...

Keyword(s):

Meat Quality ◽

Linear Trend ◽

Block Design ◽

Average Daily Gain ◽

Carcass Characteristics ◽

Control Treatment ◽

Productive Performance ◽

Zilpaterol Hydrochloride ◽

Randomized Complete Block Design ◽

Daily Gain

Twenty-four Dorper x Pelibuey lambs were housed in individual pens during a 31-d feeding period and assigned to four treatments (n = 6) under a randomized complete block design with different daily doses of zilpaterol hydrochloride (ZH): 0 (control), 0.1, 0.2, and 0.3 mg/kg BW to determine the effects of ZH supplementation on productive performance, meat quality, and wholesale cut yields. Final BW (p = 0.02) and average daily gain (ADG, p = 0.04) were greater in lambs supplemented with 0.2 mg/kg BW. Supplemental ZH tended to improve dry matter intake (DMI, p = 0.008) and ADG:DMI ratio (p = 0.078). Wholesale cut yields were not affected by ZH supplementation. Percentage of head was greater (p = 0.04) in lambs treated with ZH. The ZH supplementation did not affect carcass characteristics. However, longissimus thoracis et lumborum (LTL) presented a linear trend (p = 0.08) of increasing with ZH supplementation. Percentage of blood presented a trend (p = 0.051) of decreasing with ZH supplementation. Also, liver decreased in size (p < 0.05) for treatments where ZH was included. Values of luminosity decreased (p < 0.02) when ZH dosage increased. The value of protein Lowry was greater, with 0.3 mg kg−1 (p = 0.04). Cathepsin B + L was greater in the lambs from the control treatment (p = 0.05). In conclusion, using a daily ZH dosage of 0.2 mg per kg of BW produced the best productive performance, carcass characteristics, and some changes in the meat of hair-breed lambs.

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4 Effect of Inclusion Rate of Silage With or Without the Presence of Alpha-Amylase on Feedlot Performance, Carcass Characteristics, and Efficiency Measures

Journal of Animal Science ◽

10.1093/jas/skaa054.216 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 126-126

Author(s):

Warren C Rusche ◽

Julie Walker ◽

Zachary K Smith

Keyword(s):

Block Design ◽

Average Daily Gain ◽

Alpha Amylase ◽

Feed Ratio ◽

Feedlot Performance ◽

Live Animal ◽

Efficiency Measures ◽

Inclusion Rate ◽

Rate Interaction ◽

Daily Gain

Abstract One hundred ninety-two Continental × British steers (initial BW 420 kg [SD 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 (CON) or increased expression of alpha-amylase (Enogen, Syngenta Seeds, LLC, ENO) hybrid fed at either 12% (12SIL) or 24% (24SIL) of diet DM. Steers were blocked (n = 5) 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. There were no silage source by inclusion rate interactions detected for live growth performance. Silage source did not affect live based 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 G:F (P = 0.01) but increased FBW (P = 0.02) compared to 12SIL. A source by inclusion rate interaction was detected (P = 0.04) for calculated yield grade (YG) with steers fed 24% silage having increased YG within CON but not ENO. Hot carcass weight and ribfat were unaffected by silage source (P ≥ 0.81), but were increased by feeding 24% silage (P = 0.03 and P = 0.02, respectively). Feeding increased amounts of silage increased beef produced per hectare (P = 0.05). Conventional silage produced more beef per hectare (P < 0.01) due to differences in silage yield, but source of silage did not affect feedlot performance independent of silage yield. Feeding increased amounts of silage reduced DM efficiency on a live animal basis but increased beef produced per hectare which is of major value to cattle feeders who produce the majority of their own feedstuffs.

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172 Effects of Dietary Valine, Isoleucine, and Tryptophan Supplementations to Diets Containing Excess Leucine from Corn Protein on Growth Performance of Growing Pigs

Journal of Animal Science ◽

10.1093/jas/skab054.103 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 61-62

Author(s):

Woongbi Bi Kwon ◽

Jose A Soto ◽

Hans H Stein

Keyword(s):

Block Design ◽

Control Diet ◽

Average Daily Gain ◽

Growing Pigs ◽

Experimental Unit ◽

Negative Effects ◽

Final Body Weight ◽

Corn Protein ◽

Dietary Treatments ◽

Daily Gain

Abstract An experiment was conducted to test the hypothesis that addition of Val, Ile, or Trp alone or in combination will reduce the negative effects of excess Leu in diets for growing pigs. A total of 288 growing pigs (28.6 ± 2.5 kg) were randomly assigned to 1 of 9 dietary treatments in a randomized complete block design. There were 2 barrows and 2 gilts in each pen and 8 replicate pens per treatment. A control diet based on corn and soybean meal and 8 diets based on corn and a high-protein corn product (48% crude protein) with 2 levels of crystalline L-Val (0 or 0.10%), L-Ile (0 or 0.10%), and L-Trp (0 or 0.05%) were formulated. The crystalline L-Val, L-Ile, and L-Trp increased standardized ileal digestible (SID) Val:Lys from 70 to 80%, SID Ile:Lys from 53 to 63%, and SID Trp:Lys from 18 to 23%, respectively. All diets were formulated to contain 1.00% SID Lys and the 8 diets containing corn protein contained 171% SID Leu:Lys. Individual pig weights were recorded at the beginning and at the conclusion of the 28-d experiment. Data were analyzed using the PROC MIXED of SAS with a pen as the experimental unit. Diet was the fixed effect and block and replicate within block were random effects. Results indicated that final body weight and average daily gain were not different between pigs fed the control diet and pigs fed the diet with Val and Trp addition, but greater (P < 0.001) than for pigs fed the diet with Val addition, Ile addition, Trp addition, Val and Ile addition, Ile and Trp addition, or Val, Ile, and Trp addition (Table 1). In conclusion, addition of Val and Trp to diets with excess Leu may prevent negative effects of excess Leu in diets for growing pigs.

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

Translational Animal Science ◽

10.1093/tas/txaa190 ◽

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 < 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.

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Influence of ractopamine hydrochloride and days on feed on feedlot performance and red meat yield in thin cull beef cows targeted for a lean market

Translational Animal Science ◽

10.1093/tas/txz184 ◽

2019 ◽

Vol 4 (1) ◽

pp. 170-181 ◽

Cited By ~ 1

Author(s):

Jonathan C DeClerck ◽

Loni W Lucherk ◽

Nathan R Reeves ◽

Mark F Miller ◽

Bryan C Bernhard ◽

...

Keyword(s):

Average Daily Gain ◽

Red Meat ◽

Carcass Weight ◽

Feed Ratio ◽

Experimental Unit ◽

Feedlot Performance ◽

Meat Yield ◽

Cull Cows ◽

Ractopamine Hydrochloride ◽

Compensatory Gain

Abstract Thin, beef, cull cows [n = 144; initial body weight (BW) = 465.8 ± 56.9 kg, initial body condition score (BCS) = 2.13 ± 0.68] were serially slaughtered to evaluate the relationship between ractopamine hydrochloride (RH) administration and days on feed (DOF) on feedlot performance and carcass cutout value in a lean cow market. Cows were organized into a 3 × 2 factorial arrangement of treatments (48 pens, 8 pens per treatment, 3 cows per pen) and blocked by BW nested within pregnancy status. Treatment pens were top-dressed 400 mg per cow per day of RH (Actogain 45; Zoetis, Parsippany, NJ) for the final 28 d prior to slaughter to cows spending 28, 42, or 56 DOF. Pen served as the experimental unit, for all calculations. No RH × DOF interactions were detected (P ≥ 0.11), indicating that despite a majority of compensatory gain occurring during the first 28 d of the trial, the magnitude of the RH response was not affected by DOF. Compared to controls, RH incited improvements in feedlot performance, but had a greater extent on carcass weight gain and efficiency. Specifically, RH improved average daily gain (ADG) by 13.7% (P = 0.04) and carcass ADG by 16.9% (P = 0.02) Cattle fed RH displayed a 15.5% improved gain to feed ratio (P = 0.02) and a 20% improved carcass gain to feed ratio (P = 0.05). Inclusion of RH in the finishing diet increased hot carcass weight by 4.5% (P = 0.05; 12.9 kg). However, supplementation of RH did not alter red meat yield (P ≥ 0.16), but provoked a 11.1% improvement in lean maturity (P < 0.01). Evaluation of the main effect of DOF provided insight into the compensatory state of beef cull cows on a high-concentrate diet. Serial slaughter offal weights presented confounding results. With additional DOF, a numerical increase in liver weights (P = 0.20) suggested that organ tissue replenishment occurred throughout the trial, and cattle experienced compensatory gain during the entire feeding phase. In contrast, lung and heart weights were not altered, while kidney tended to decrease linearly (P = 0.08) despite additional DOF. Furthermore, extending DOF generated a linear increase in dry matter intake (P < 0.01) yet a tendency for a decline in ADG (P = 0.10), reinforcing the premise that most of compensatory gain occurred during the first 28 d of the trial. If thin (BCS ≤ 4), healthy candidates can be finished, feeders can reap the benefits of an additive relationship between compensatory gain and RH.

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Effects of various ractopamine hydrochloride withdrawal periods on performance, health, and carcass characteristics in yearling steers

Translational Animal Science ◽

10.1093/tas/txz148 ◽

2019 ◽

Vol 4 (1) ◽

pp. 67-74

Author(s):

Tony C Bryant ◽

Josh I Szasz ◽

Lois F G Pringle ◽

Eddie Crispe ◽

K Shawn Blood ◽

...

Keyword(s):

Feed Efficiency ◽

Dry Matter ◽

Block Design ◽

Average Daily Gain ◽

Carcass Characteristics ◽

Average Dose ◽

Withdrawal Period ◽

Feedlot Performance ◽

Dressing Percentage ◽

Ractopamine Hydrochloride

Abstract Ractopamine hydrochloride (RAC) is a β-adrenergic agonist approved for feeding during the last 28 to 42 d prior to cattle slaughter to improve feedlot performance and carcass characteristics. Three thousand crossbred yearling steers (527 ± 2.4 kg; AVG ± SD) were used in two periods to evaluate the effects of various RAC withdrawal times on feedlot performance, health, and carcass characteristics. In Period 1, 6 blocks of 30 pens totaling 1,500 steers were utilized, which was repeated for Period 2. In a randomized complete block design, cattle were assigned to 1 of 5 treatments consisting of 1) No RAC fed (CON), 2) 12-h RAC withdrawal (12-hRAC), 3) 2-d RAC withdrawal (2-dRAC), 4) 4-d RAC withdrawal (4-dRAC), and 5) 7-d RAC withdrawal (7-dRAC). Cattle were fed for a total of 62 d, and applicable treatments were supplemented with 30.0 ppm (dry matter basis) of RAC (average dose = 322 mg per steer per day) for 33 d at the end of the feeding period, corresponding to their respective withdrawal times. Initial body weight (BW) displayed a quadratic curve, with 2-dRAC and 4-dRAC withdrawal periods having the greatest BW. Accordingly, dry matter intake (DMI) responded quadratically (P = 0.034), with 2-dRAC and 4-dRAC treatments demonstrating the greatest DMI. No significant treatment differences (P ≥ 0.641) were observed in final live BW, average daily gain (ADG), or feed efficiency. Alternatively, when using a common dressing percentage to calculate live BW, cattle on RAC treatments exhibited 7.6 kg additional live BW (P < 0.001) compared to CON cattle. Furthermore, carcass-adjusted ADG and feed efficiency did not differ (P > 0.10) between RAC treatments but were improved compared to the CON treatment (P ≤ 0.002). Hot carcass weight (HCW) was on average 4.9 kg greater (P < 0.001) for RAC treatments vs. CON, and no differences were detected (P > 0.10) among RAC treatments. Within RAC treatments, carcass cutability responded quadratically (P ≤ 0.005) to withdrawal period, with the 2-dRAC and 4-dRAC treatments containing more Yield Grade 4 and 5 and fewer Yield Grade 1 and 2 carcasses than the other RAC treatments. On the basis of the results of this experiment, feeding RAC improves dressing percentage, HCW, and carcass-adjusted BW, ADG, and feed efficiency. Furthermore, extending the RAC withdrawal period to 7 d does not have a significant impact on cattle performance or health and has minimal effects on carcass characteristics.

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PSX-29 Levels of hay and narasin inclusion on carcass characteristics and meat composition

Journal of Animal Science ◽

10.1093/jas/skz258.896 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 455-455

Author(s):

Lairana A Sardinha ◽

Daniel M Polizel ◽

Alexandre A Miszura ◽

Arnaldo C Limede ◽

José P R Barroso ◽

...

Keyword(s):

Body Weight ◽

Block Design ◽

Carcass Characteristics ◽

Ash Content ◽

Carcass Weight ◽

Initial Body Weight ◽

Composition Data ◽

Meat Composition ◽

Randomized Complete Block Design ◽

Different Levels

Abstract The objective of this study was to determinate the effects of narasin on carcass characteristics of lambs fed a diet containing different levels. Forty-four lambs were allotted in a randomized complete block design, defined by initial body weight (BW), in a 2x2 factorial arrangement. The first factor was forage (coastcross hay) inclusion (10 or 20%, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis). The experiment lasted 112 days. At the end of the experiment, the lambs were slaughtered to evaluate the carcass characteristics and meat composition. Data were analyzed using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. The effects were considered significant when P < 0.05. There was no interaction between forage levels and narasin inclusion. The experimental diets did not affect the slaughter BW (54.8 ± 1.6 kg), hot carcass weight (29.3 ± 0.96 kg), dressing percentage (53.5 ± 0.67%) and LM area (18.8 ± 0.89 cm2). The inclusion of narasin increased 12th-rib fat (2.10 vs 2.75 mm; P < 0.01) and BW thickness (16.9 vs 20.2 mm; P < 0.01). The inclusion of 20% of hay decreased BW thickness (19.21 vs 17.9 mm; P = 0.03). The experimental diets did not affect the moisture (74.2 ± 0.53%) and ash content in meat (1.27 ± 0.04%). Narasin inclusion increased the fat (2.81 vs 3.62%; P < 0.01) and decreased the CP (21.3 vs 20.7%; P = 0.02) in meat composition. The inclusion of 10% of hay increased the fat in meat (3.5 vs 2.9%; P = 0.03), however, did not affect the CP content. In conclusion, the narasin inclusion and levels of hay improve the carcass characteristics and change the meat composition.

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