Relationship among cattle breed and anabolic implant protocol relative to feedlot performance: Growth, temperament, feeding behavior, carcass traits, and economic return

Recent research has suggested that different cattle breed types may respond differently to anabolic implant protocols of varying intensity. Therefore, the purpose of this research was to compare anabolic implant protocols in feedlot steers of 2 different breed types. Sixty steers were stratified by weight and breed in a 2 × 3 factorial design examining 2 different breeds: Angus (AN; n=38) or Santa Gertrudis influenced (SG; n=22), and 3 implant strategies: no implant (CON; n=20), a moderate intensity implant protocol (d0 implant: Revalor-G, d56 implant: Revalor-IS, d112 implant: Revalor-S; MI; n=20), or a high intensity implant protocol (d0 implant: Revalor-IS, d56 implant: Revalor-S, d112 implant: Revalor-200; HI; n=20). Steers were randomly placed into pens equipped with GrowSafe bunks to collect dry matter intake and feeding behavior. All animals were fed the same diet. Weight, chute score, exit velocity, serum, rectal temperature, hip height and 12th rib fat thickness were collected approximately every 28 d over a 196 d period. Serum urea nitrogen (SUN) was evaluated as well. Total average daily gain was increased (P < 0.0001) in both the HI and MI steers compared to the CON steers by 29.4% and 26%, respectively. A treatment × breed interaction was observed (P < 0.0001) for hip height, with AN-CON steers being shorter (P < 0.0007) than AN-HI, SG-CON, SG-MI, and SG-HI steers. A breed × treatment interaction was observed (P < 0.004) for chute score and rectal temperature, with SG-HI and SG-MI steers having increased chute scores (P < 0.001) when compared to AN-HI, AN-MI, AN-CON, and SG-CON throughout the course of the trial. Additionally, SG-HI and SG-MI steers had an increased rectal temperature (P < 0.004) compared to AN-HI, AN-MI, AN-CON, and SG-CON steers. A breed effect was observed (P = 0.002) for SUN with AN steers having increased (P = 0.002) SUN concentration compared to SG sired steers, in addition to a treatment effect (P < 0.0001), with CON steers having a higher (P < 0.0001) SUN concentration than MI and HI steers, regardless of breed. The MI implant protocol increased net return per head, on average, by $97.28, regardless of breed, while the HI implant protocol increased net return by only $80.84. Taken together, despite the cattle breed types responding differently to the different anabolic implant protocols at times, a moderate intensity anabolic implant protocol was optimal in this experiment for steers raised in a temperate climate.

 

Comments:

The research aimed to compare the effects of anabolic implant protocols on feedlot steers of two different breed types, Angus (AN) and Santa Gertrudis influenced (SG). The study used a 2 × 3 factorial design, with two breeds and three implant strategies: no implant (CON), a moderate intensity implant protocol (MI), and a high intensity implant protocol (HI).

Sixty steers were selected and stratified by weight and breed, with 38 Angus and 22 Santa Gertrudis influenced steers. The steers were randomly assigned to different pens equipped with GrowSafe bunks to monitor dry matter intake and feeding behavior. All steers were fed the same diet throughout the 196-day trial period.

Various measurements and observations were recorded approximately every 28 days. These included weight, chute score, exit velocity, serum parameters, rectal temperature, hip height, and 12th rib fat thickness. Serum urea nitrogen (SUN) concentration was also evaluated.

The results showed that both the high intensity (HI) and moderate intensity (MI) implant protocols significantly increased total average daily gain compared to the non-implanted (CON) steers. The HI protocol increased average daily gain by 29.4%, while the MI protocol increased it by 26%.

A significant interaction between breed and treatment was observed for hip height. AN-CON steers were shorter than AN-HI, SG-CON, SG-MI, and SG-HI steers. There was also a significant breed × treatment interaction for chute score and rectal temperature. SG-HI and SG-MI steers had higher chute scores and rectal temperatures compared to AN-HI, AN-MI, AN-CON, and SG-CON steers.

The analysis also revealed a breed effect on serum urea nitrogen (SUN) concentration, with AN steers having higher SUN concentration compared to SG-sired steers. Additionally, there was a treatment effect, with CON steers having higher SUN concentration than MI and HI steers, regardless of breed.

In terms of economic implications, the MI implant protocol resulted in a higher net return per head ($97.28) on average, regardless of breed, compared to the HI implant protocol ($80.84).

In conclusion, while the different cattle breed types responded differently to the various anabolic implant protocols, the moderate intensity implant protocol (MI) was found to be optimal for steers raised in a temperate climate in this experiment. It resulted in increased average daily gain and higher net return per head compared to the non-implanted and high intensity implant groups.