Feedlot Performance and Carcass Traits of Texas Rambouillet Feeder Lambs Implanted With Growth Implants

Abstract

Three hundred cross-bred lambs with an average initial weight of 33.5 kg were used to compare the effects of three different hormone implants versus a control on lamb performance (ADG) and carcass characteristics.  Lambs were divided into four groups and assigned implant treatments as follows: no implant (CON), Synovex1 (SYN), Ralgro2 (RAL), or Component C3 (COM).  On d 0, lambs were weighed, ear tagged and implanted according to treatment.  Lambs were fed by a self-feeder.  Weights were recorded on subsequent d 28, 56, 84, 97, and 108 and as end-weights were reached, lambs were slaughtered.  Backfat thickness, cross-sectional ribeye area, USDA yield and quality grade measurements were recorded.  Analysis showed significantly higher ADG (P < 0.05) in COM and SYN lambs compared to CON d 28 through d 108.  On d 56, RAL lambs also exhibited higher (P < 0.05)  ADG than CON lambs.  Carcass evaluations yielded no conclusive evidence of improved quality of implanted vs. CON carcasses.  A majority (95%) of carcasses received “choice” quality grades and yield grades of 3 to 5 thereby implying improved ADG with hormone implant use, with no simultaneous improvements in carcass quality.