scholarly journals Anabolic Implants Varying in Hormone Type and Concentration Influence Performance, Feeding Behavior, Carcass Characteristics, Plasma Trace Mineral Concentrations, and Liver Trace Mineral Concentrations of Angus Sired Steers

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1964
Author(s):  
Caleb C. Reichhardt ◽  
Elizabeth M. Messersmith ◽  
Tevan J. Brady ◽  
Laura A. Motsinger ◽  
Reganne K. Briggs ◽  
...  
Keyword(s):  
Body Weight ◽  
Feed Efficiency ◽  
Animal Health ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Trace Mineral ◽  
Trenbolone Acetate ◽  
Mineral Concentrations ◽  
Anabolic Implants ◽  
Daily Gain

Fifty Angus-sired steers were utilized to evaluate the effects of anabolic implants varying in hormone type and concentration on performance, carcass traits, and plasma and liver trace mineral concentrations over 129 d. Steers were stratified by weight into one of four (n = 12 or 13/treatment) implant treatments: (1) estradiol (E2; 25.7 mg E2; Compudose, Elanco Animal Health, Greenfield, IN, USA), (2) trenbolone acetate (TBA; 200 mg TBA; Finaplix-H, Merck Animal Health, Madison, NJ, USA), (3) combination implant (ETBA; 120 mg TBA + 24 mg E2; Revalor-S, Merck Animal Health), or (4) no implant (CON). Steers were randomly assigned to pens equipped with GrowSafe bunks and fed a corn and barley-based finishing ration. Overall average daily gain and body weight were greater for ETBA and TBA than CON (p ≤ 0.04), but not E2 (p ≥ 0.12). Feed efficiency and hot carcass weight were only greater than CON for ETBA (p ≤ 0.03). Plasma and d 2 liver Zn concentrations were lesser for ETBA than CON (p ≤ 0.01) and d 10 liver Mn was lesser (p = 0.0003) for TBA than CON. These data indicate that implants containing TBA influence growth and trace mineral parameters, though more work investigating this relationship is necessary.

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 < 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.

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 < 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 Effect of zinc source and implant strategy on performance, carcass characteristics, and trace mineral concentrations in finishing feedlot steers

2021 ◽  
Author(s):  
Elizabeth M Messersmith ◽  
Stephanie L Hansen
Keyword(s):  
Repeated Measures ◽  
Fixed Effects ◽  
Animal Health ◽  
Carcass Characteristics ◽  
Experimental Unit ◽  
Trace Mineral ◽  
Trenbolone Acetate ◽  
Zn Concentration ◽  
Mineral Concentrations ◽  
Future Work

Abstract Seventy-two Angus-crossbred steers (411 ± 16 kg) were assigned to a 2 × 3 factorial arrangement of treatments to examine the effects of blended Zn source supplementation on performance, carcass characteristics, and trace mineral parameters of steers administered no implant or a two-implant program. Factors included implant (IMP) strategies and Zn supplementation. During the 126-d study steers were either not implanted (NoIMP) or implanted (IS/200; Elanco, Greenfield, IN) on d 0 (Component TE-IS; 80 mg trenbolone acetate + 16 mg estradiol) and 57 (Component TE-200; 200 mg trenbolone acetate + 20 mg estradiol). All steers were fed 70 mg Zn/kg on a dry matter (DM) basis from ZnSO4 + 30 mg Zn/kg DM from either basic ZnCl (Vistore Zn, Phibro Animal Health, Teaneck, NJ), Zn glycinate (Gemstone Zn, Phibro Animal Health), or ZnSO4 (ZnB, ZnG, or ZnS, respectively). Steers were blocked by weight into pens of 6 and fed a dry rolled corn-based diet via GrowSafe bunks (GrowSafe Systems Ltd.; Airdrie, AB, Canada). Data were analyzed using the Mixed Procedure of SAS, with fixed effects of Zn, IMP, and the interaction. Steer was the experimental unit (n = 12 steers/treatment). Liver and muscle collected on d -5, 14, 71, and 120 were analyzed for Zn concentration, and data were analyzed as repeated measures (repeated effect = Day). An IMP × Zn tendency (P = 0.07) was observed for d 126 body weight with no effects of Zn within NoIMP while ZnS tended to be heavier than ZnB with ZnG intermediate within IS/200. Carcass-adjusted overall feed efficiency (G:F) was greatest for ZnS (Zn; P = 0.02). Implanted cattle had greater DM intake, G:F, and carcass-adjusted performance (P ≤ 0.01). Liver Zn concentrations were greater for IS/200 by d 120 (IMP × Day; P = 0.02). Within IS/200, ZnG tended to have greater muscle Zn than ZnS while ZnB was intermediate (Zn × IMP; P = 0.09). No Zn or IMP × Zn (P ≥ 0.12) effects were observed for carcass data. However, IS/200 had greater hot carcass weight, dressing percentage, and ribeye area than NoIMP (P ≤ 0.001). These data suggest implants improve growth and influence Zn metabolism. Future work should examine Zn sources and supplementation alongside implant strategies.

scholarly journals Essential Oils in the Diet of Crossbred (½ Angus vs. ½ Nellore) Bulls Finished in Feedlot on Animal Performance, Feed Efficiency and Carcass Characteristics

2017 ◽  
Vol 9 (10) ◽  
pp. 205 ◽  
Author(s):  
Dayane Cristina Rivaroli ◽  
Rodolpho Martin Do Prado ◽  
Mariana Garcia Ornaghi ◽  
Camila Mottin ◽  
Tatiane Rogério Ramos ◽  
...  
Keyword(s):  
Body Weight ◽  
Essential Oils ◽  
Feed Efficiency ◽  
Sweet Orange ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Animal Performance ◽  
Feed Conversion ◽  
Final Body Weight ◽  
Daily Gain

This experiment was carried out to evaluate the animal performance, feed efficiency and carcass characteristics of 27 crossbred bulls (½ Angus vs. ½ Nellore), finished in feedlot for 120 days, with the addition of distinct levels of essential oils in the diets. The experiment was conducted in a completely randomized trial and animals were distributed into three treatments: control (CON), addition of 500 mg/kg of DM/animal/day of a mix of essential oils (E500), and addition of 1000 mg/kg of DM/animal/day of a mix of essential oils (E1000). The essential oils supplemented to the diets were based on a combination of vegetal extracts from: oregano, garlic, lemon, rosemary, thymus, eucalyptus and sweet orange. The bulls had an average age of 12±2 months and weight of 243.4±6.8 kg when the trial started. The roughage and concentrate ratio was 10% and 90%, respectively. The inclusion of essentials oils in the diets did not affect final body weight, average daily gain, and feed intake, but there was a tendency for improved feed efficiency for the E500 treatment. The ADG ranged from 1.55 to 1.70. Average DMI and feed conversion were 7.07 kg/day and 4.31, respectively. Essentials oil levels did not affect the carcass characteristics. More studies are needed to elucidate the synergism of combinations of essential oils in the rumen.

scholarly journals 103 Effect of a single Revalor-XH or Revalor-200/Revalor-200 re-implant program and zinc supplementation on performance, carcass characteristics, and liver mineral of feedlot heifers

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 133-133
Author(s):  
Elizabeth M Messersmith ◽  
Emma Niedermayer ◽  
Grant Crawford ◽  
Stephanie L Hansen
Keyword(s):  
Feed Efficiency ◽  
Fixed Effects ◽  
Extended Release ◽  
Animal Health ◽  
Average Daily Gain ◽  
Corn Silage ◽  
Superior Performance ◽  
Trenbolone Acetate ◽  
Daily Gain ◽  
Mn Concentrations

Abstract A 169-d study utilizing 208 Angus-cross heifers (291 ± 23 kg; 4 sources) in a 2×2 factorial examined the effects of implant strategy and Zn supplementation on growth and mineral status of heifers. Factors included 2 implant (Merck Animal Health, Madison, NJ) strategies: extended-release Revalor-XH on d 0 (REV-XH; 20 mg estradiol+200 mg trenbolone acetate) or Revalor-200 on d 0 and 91 (REV-200; 20 mg estradiol+200 mg trenbolone acetate) and 2 supplemental Zn (mg/kg dry matter [DM]; ZnSO4) strategies: national (30; NRC) or industry (100; IND) recommendations. Heifers were blocked by weight within source (n = 5 or 6 heifers/pen; 9 pens/treatment), received a corn silage-based diet (d 0-56), then transitioned to a corn-based diet fed via concrete bunks. Data were analyzed in Proc Mixed of SAS; fixed effects of implant (IMP), Zn, interaction, and source with the repeated effect of time for average daily gain (ADG) and liver mineral. Initial weight served as a covariate for performance and carcass data. Revalor-200 had greater ADG from d 0-28 and 91-120, while REV-XH peaked during d 56-91 (IMP × time; P = 0.02), corresponding to likely periods of greatest hormone payout from each implant. Liver Mn concentrations decreased on d 14 regardless of implant while d 105 and 164 concentrations were lesser for REV-200 (IMP × time; P = 0.02). Hot carcass weight, DM intake, carcass-adjusted ADG and feed efficiency were not different between IMP strategies (P ≥ 0.18). Steers fed IND tended to be heavier on d 91 (P = 0.06) and were heavier on d 120 (P = 0.05) than NRC; however, final BW did not differ due to Zn (P = 0.37). The similar performance between implant strategies and superior performance during peak hormone payout by heifers supplemented IND vs. NRC suggests increased Zn may support rapid growth.

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 < 0.01) final BW, greater (P < 0.001) ADG, improved (P < 0.001) G:F, heavier (P < 0.01) HCW, and larger (P < 0.05) longissimus muscle compared to non-ractopamine supplemented steers. There was a Zn source by ractopamine interaction (P < 0.01) for dressing percentage. Cattle receiving ractopamine HCl with Zn hydroxychloride had a greater dressing percentage (P < 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 < 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 The Performance and Carcass Characteristics of Black Baladi Kids Fed Diets with Graded Quantities of Sweet Lupin Grain (Lupinus angustifolius)

2022 ◽  
Vol 9 (1) ◽  
pp. 20
Author(s):  
Belal S. Obeidat
Keyword(s):  
Body Weight ◽  
Dry Matter ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Cost Effective ◽  
Neutral Detergent Fiber ◽  
Acid Detergent Fiber ◽  
Diet Cost ◽  
Daily Gain

A study was conducted to examine how lupin grains (LUPs) feeding affected nutritional intake, digestibility, growth, and carcass characteristics in kids. A total of 24 growing black kids (initial body weight (BW) = 16.4 ± 0.49 kg) were allocated to one of three diets at random. Lupin was included in the diet at a rate of 0 (control; CON), 100 (LUP100), or 200 g/kg (LUP200) of total dry matter (DM). The trial lasted for 91 days divided into 7 and 84 days to be used for adaptation and data collection, respectively. Feed intake was evaluated daily throughout the study. At the commencement and the end of the study, each kid’s body weight was measured to determine its average daily gain (ADG). On day 70, 5 kids were chosen at random from each group to investigate nutrient in vivo digestibility and N balance. At the end of the study, all of the kids were slaughtered to examine carcass features. Nutrient intakes (neutral detergent fiber, acid detergent fiber, and ether extract) were higher (p ≤ 0.01) in LUP-containing diets than in the CON diet. The average daily gain was greater (p ≤ 0.03) in diets containing lupin grains than in the CON diet. Cost of gain ($US/kg growth) was lower (p = 0.004) in kids fed diets containing lupin than the CON diet. Dry matter and CP digestibility rates were greater (p ≤ 0.03) in lupin diets. Retained N was higher (p = 0.04) in lupin-containing diets than in the CON diet. Cold carcass weight was higher (p < 0.05) for kids consuming the LUP100 diet than the CON diet. In lupin diets, carcass cut weights were higher (p < 0.05). Results of the current study indicate that feeding black kids diets containing lupin grains at 100 or 200 g/kg DM basis is cost effective and would increase profitability.

scholarly journals Effects of restricted feeding and re-alimentation of dietary protein or energy on compensatory growth of sheep

1970 ◽  
Vol 47 (3) ◽  
pp. 389-396
Author(s):  
W. Addah ◽  
A. Ayantunde ◽  
E.K. Okine
Keyword(s):  
Growth Performance ◽  
Dietary Protein ◽  
Feed Efficiency ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
High Energy ◽  
Utilization Efficiency ◽  
Eating Quality ◽  
Nutrient Utilization Efficiency ◽  
Daily Gain

The study investigated the effects of re-alimenting dietary protein or energy on growth, carcass characteristics and meat eating quality parameters of sheep. Twenty-seven intact rams (~9 months; 11.3 ± 0.5 kg) were randomly divided into three groups. Each group was fed a maintenance diet (MT) containing, on dry matter (DM) basis, 105 g/kg crude protein (CP) and 8.4 MJ/kg DM metabolizable energy (ME) for 30 days. Thereafter, they were continually fed the same MT or re-alimented with a high protein diet (HP) containing 169 g/kg DM CP and 9.3 MJ/kg ME or a high energy diet (HE) containing 123 g/kg DM CP and 10.6 MJ/kg ME for an additional 30 days to determine the effects of re-alimentation of protein or energy on their growth performance and carcass characteristics. During the initial 30-day period, DM intake (DMI) and growth performance were similar among the three groups. However, upon re-alimentation, average daily gain (ADG) and feed efficiency of sheep re-alimented with HP were greater than those maintained continually on MT or re-alimented with HE. Sheep on HP had higher feed efficiency, ADG and heavier carcasses than those fed MT or re-alimented with HE during the whole 60-day period. Growth of most viscera was less responsive to the restriction-re-alimentation feeding regimen except for the weights of the lungs, heart and intestines. Meat from sheep re-alimented with HE had a more intense ‘sheepy’ flavour than those fed MT or re-alimented with HP, but juiciness and tenderness were not affected. The higher ADG of sheep re-alimented with protein may be related more to enhanced efficiency of feed utilization than to higher DMI.Keywords: average daily gain, feed restriction, nutrient utilization efficiency, visceral organs

scholarly journals PSXIV-34 Encapsulated nitrate on performance of growing Nellore bulls under grazing system during the dry season

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 431-432
Author(s):  
Cibelle B Figueiredo ◽  
Mauricia B Silva ◽  
Juliano Fernandes ◽  
Alana M Calaça ◽  
Higor Rocha ◽  
...  
Keyword(s):  
Body Weight ◽  
Ammonium Nitrate ◽  
Feed Efficiency ◽  
Dry Matter ◽  
Average Daily Gain ◽  
Dry Season ◽  
Dry Matter Intake ◽  
Calcium Ammonium Nitrate ◽  
Randomized Design ◽  
Daily Gain

Abstract The aim of this trial was to evaluate the effect of encapsulated calcium ammonium nitrate as a partial substitute for soybean meals in the concentrate dry matter intake, average daily gain and feed efficiency of Nellore young bulls under grazing conditions, during the dry season. Sixty-four weaned Nellore (initial BW = 177.46±3.77 kg and 9 mo old) were used in a completely randomized assay. The study lasted 84 days on the dry season. Animals were allotted into 16 paddocks of 1.0 ha each of Urochloa brizantha, randomly assigned into one of two treatments: (CTL) supplement with 25% CP, without nitrate inclusion and; (ENP): supplement with 25% CP, with a inclusion of 50 g of encapsulated calcium ammonium nitrate to each 100 kg of body weight. Animals were fed with concentrate at 1.0% of body weight. Concentrate offered was monitored daily as well as his refusals were collected and weighed to determine daily concentrate dry matter intake (DMI) and feed efficiency (F:G). Animals were weighed every 28 d for calculating average daily gain (ADG). Data were analyzed as a completely randomized design, using ANOVA (α = 0.05). No effects of treatments (P &gt; 0.3487) were observed for final BW (246.69 kg). The same for concentrate dry matter intake (P &gt; 0.0550). Animals consumed 2.34 kg of supplement per day. The average daily gain (0.832 kg, P &gt; 0.2649) and feed efficiency (0.356 kg, P &gt; 0.7315) were not affected by the inclusion of nitrate. The inclusion of encapsulated calcium ammonium nitrate in supplement to Nellore young bulls under grazing conditions during the growing phase did not affect the performance.

scholarly journals Zinc supplementation strategies in feedlot heifers receiving an extended-release implant or an aggressive re-implant program

2021 ◽  
Author(s):  
Elizabeth M Messersmith ◽  
Emma K Niedermayer ◽  
Kara J Thornton ◽  
Grant I Crawford ◽  
Stephanie L Hansen
Keyword(s):  
Body Weight ◽  
Muscle Fiber ◽  
Extended Release ◽  
Block Design ◽  
Animal Health ◽  
Average Daily Gain ◽  
Cross Sectional ◽  
Final Body Weight ◽  
Trenbolone Acetate ◽  
Growing Period

Abstract Two-hundred and eight Angus-crossbred heifers (291 ± 23 kg) from four sources were used in a randomized complete block design. The objective of the study was to determine the effects of implant strategy and Zn supplementation on performance, carcass characteristics, muscle fiber diameter, and mineral status of heifers. Heifers were assigned to a 2 × 2 factorial study for 168 d, factors included Zn and implant (IMP). Heifers were supplemented Zn (mg/kg dry matter [DM]; ZnSO4) at national (30; NRC) or industry (100; IND) recommendations. Implant strategies (Merck Animal Health, Madison, NJ) included extended-release Revalor-XH on d 0 (REV-XH; 20 mg estradiol + 200 mg trenbolone acetate) containing 4 uncoated pellets and 6 coated pellets or the uncoated implant Revalor-200 on d 0 and again on d 91 (REV-200; 20 mg estradiol + 200 mg trenbolone acetate). Heifers were blocked by weight within source to pens of 5 or 6 heifers per pen (9 pens per treatment). A corn silage-based diet was fed during the growing period (d 0-55) followed by transition to a corn-based finishing diet. Weights were taken consecutively on d -1/0, 55/56, and 167/168. Liver and muscle from the longissimus thoracis were collected from one heifer per pen on d -5, 14, 105, and 164. Data were analyzed via Mixed Procedure of SAS. Average daily gain (ADG) and liver mineral used Period as the repeated effect. Corresponding to periods of high hormone payout from each implant, d 0-28 and 91-120 ADG were greatest for REV-200, while REV-XH numerically peaked during d 56-91 (IMP × Period; P = 0.02). Day 91 IND body weight tended to be heavier (P = 0.06) and d 120 body weight was heavier (P = 0.05) than NRC heifers. No effect of Zn or IMP on final body weight was observed (P ≥ 0.21). Muscle fiber cross-sectional diameter on d 164 was greater (P = 0.05) in IND than NRC. Liver Mn concentrations decreased by d 14 regardless of implant, though d 105 and 164 concentrations were lesser for REV-200 than REV-XH (IMP × Period; P = 0.02). No effects of Zn, IMP, or the interaction were observed for carcass-adjusted gain to feed, d 0-168 DM intake, hot carcass weight, or ribeye area (P ≥ 0.11). The nominal differences in performance between implant strategies suggests extended-release implants may be an effective implant strategy to replace re-implant programs in heifers, while the improved performance of heifers fed IND vs. NRC during times of peak hormone payout suggests a role for Zn in periods of rapid growth.

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