A pooled analysis of six large-pen feedlot studies: effects of a noncoated initial and terminal implant compared with a single initial and delayed-release implant on arrival in feedlot heifers

Abstract

<jats:title>Abstract</jats:title> <jats:p>Randomized complete block design experiments (n = 6 experiments) evaluating steroidal implants (all from Merck Animal Health, Madison, NJ) were conducted in large-pen feedlot research facilities between 2015 and 2018 comparing an 80 mg trenbolone acetate (TBA) and 8 mg estradiol-17β (E2) initial implant (Revalor-IH) and re-implanted with 200 mg TBA and 20 mg E2 (Revalor-200; REPEATED) to a single 80 mg TBA and 8 mg E2 uncoated; 120 mg TBA and 12 mg E2 coated implant (Revalor-XH) at arrival (SINGLE) on growth and carcass responses in finishing heifers. Experiments occurred in Nebraska, Oklahoma, Washington, and Texas. Similar arrival processing was used across experiments where 17,675 heifers [initial BW = 333 kg SEM (4.1)] were enrolled into 180 pens (90 pens/treatment with 65 to 240 heifers/pen) and fed for 145 to 222 d. Only REPEATED heifers were removed from their pen at re-implant. Diets contained monensin and tylosin, consisted of ingredients common to each region, and contained greater than 90% concentrate. Ractopamine hydrochloride was fed for a minimum of 28 d prior to harvest. Linear mixed-models were used for all analyses; model-adjusted means for each implant group and the corresponding SEM were generated. Distributions of USDA quality (QG) and yield grade (YG) were analyzed as ordinal outcomes. No differences (P ≥ 0.11) were detected for any performance parameters except DMI, where SINGLE had greater (P = 0.02) DMI (9.48 vs. 9.38 ± 0.127 kg) compared with REPEATED. Heifers implanted with REPEATED had greater (P ≤ 0.02) HCW (384 vs. 382 ± 2.8 kg), dressing percentage (64.54 vs. 64.22 ± 0.120%), and ribeye area (91.87 vs. 89.55 ± 0.839 cm2), but less (P ≤ 0.01) rib fat (1.78 vs. 1.83 ± 0.025 cm) and calculated YG (2.82 vs. 2.97 ± 0.040), and similar (P = 0.74) marbling scores (503 vs. 505 ± 5.2) compared with SINGLE heifers. Distributions of USDA YG and QG were impacted (P ≤ 0.03) by treatment such that, REPEATED had fewer USDA Prime and YG 4 and 5 carcasses. Heifer growth performance did not differ between implant regimens, but HCW and muscling did; perhaps indicating that REPEATED may be suited for grid-based marketing, and SINGLE might be suited for heifers sold on a live basis depending upon market conditions and value-based grid premiums and discounts. However, these decisions are operational dependent, and also may be influenced by factors including animal and employee safety, stress on animals, processing facilities, time of year, labor availability, and marketing strategies.</jats:p>

Synovex ONE Grower improves growth performance for at least 200 days in growing beef steers and heifers fed in confinement for slaughter

“…Heifers saw an 8.9% response in ADG after implantation of ONE Grower over a 200-d feeding period which resulted in a 0.11 kg/d improvement in ADG. As evidenced in this study, the use of long-acting implants such as ONE Grower greatly improved final BW and ADG through 200 d. Although not researched in this study, with treatments commingled within pen, historical data utilizing implants suggest that use of ONE Grower for at least 200 d would likely increase DMI and gain efficiency compared to Control ( Smith et al, 2019a , 2020 ). This is further supported by the Synovex ONE Feedlot approval work which resulted in a 4.7 and 4.5% increase in DMI for steers and heifers, respectively, while seeing an 8.0% and a 7.0% increase in gain efficiency for steers and heifers, respectively ( Cleale et al, 2012 ).…”

“…Growth-promoting implants are a technology that provides a great improvement in feedlot cattle performance and a substantial return on investment to feedlot operators ( Duckett et al, 1996 ) which has resulted in over 90% of feedlot cattle being implanted at least once ( NAHMS, 2013 ) during the feedlot period. Cattle implanted with TBA and estradiol (either estradiol-17β [E 2 ] or EB) were shown to repeatedly improve ADG, DMI, and feed conversion while reducing marbling score and USDA yield grade ( Smith et al, 2019b , 2020 ).…”

Effects of Corn Silage Inclusion Level and Type of Anabolic Implant on Animal Growth Performance, Apparent Total Tract Digestibility, Beef Production per Hectare, and Carcass Characteristics of Finishing Steers

“…This was likely due to alterations of implant type on adipogenic gene expression [ 27 , 28 ], although this was not evaluated in the present study. Others have indicated that marbling is increased in heifers administered a single coated implant or an initial and terminal implant with a non-coated implant [ 29 , 30 ].…”

A randomized trial and multisite pooled trial analyses comparing effects of two hormonal implant programs and differing days-on-feed on carcass characteristics and feedlot performance of beef heifers

“…As changes in carcass composition may be expected when comparing Revalor-XH to a more traditional re-implant program ( Smith et al, 2020 ), it may also be important to evaluate optimal days-on-feed (DOF) when using differing implant programs. Including a serial harvest treatment factor is a method for estimation of incremental dressing percentage (incremental carcass gain/incremental live gain), the estimated proportion of live weight gain that results in carcass weight gain ( Streeter et al, 2012 ).…”