Interactions between cattle breed type and anabolic implant strategy impact circulating serum metabolites, feedlot performance, feeding behavior, carcass characteristics, and economic return in beef steers

The effects of including sprouted barley with alfalfa hay in the diet on ruminal health and performance of cow-calf pairs

The world population is growing exponentially, increasing demand to produce high-quality protein for human consumption. Changes in weather patterns, drought, and decreased land resources due to urbanization have increased the strain on the agriculture sector to meet world demands. An alternative method to combat these issues and continue to produce high-quality livestock feed would be through a controlled environment vertical farming system. Commonly, cereal grains, such as barley, are used in these systems to produce livestock feed. However, there is little information on the viability of feeding sprouted grains to beef cattle. Two diets of either feeder-quality alfalfa hay (n = 10 pairs; ALF) or the same alfalfa hay and sprouted barley (SB; 12.6% dry matter [DM]; n = 10 pairs) were fed for 90 d to Angus pairs with a steer calf during mid to late lactation. On days 0 and 90, body weight (BW), milk, rumen fluid, and body condition score were collected from cows and hip height and BW were recorded for calves. On day 10, BW was recorded for cows and calves and rumen fluid was collected from cows. Rumen fluid was also collected from cows on day 45. On day 55, BW was collected for both cows and calves and milk from cows. Intake was recorded throughout the trial via bunks with Vytelle technology. The PROC MIXED procedure of SAS was used to analyze all data with the day as a repeated measure to determine the main effect of diet. Individual volatile fatty acids (VFA) were measured as a percent of total VFA. No differences (P ≥ 0.16) were observed in calf BW, hip height, milk protein, fat, lactose, calf DM intake (DMI), or cow DMI. Cows fed SB tended (P = 0.08) to have a decreased somatic cell count compared to ALF. Percent butyrate was impacted by diet × day (P = 0.02), but no difference (P > 0.09) at any time points were detected. Additionally, a diet × day effect (P = 0.001) on rumen pH demonstrated that both groups stayed consistent until day 45 and then SB pH decreased the last 45 d. There was a day effect for total VFA (P = 0.0009), acetate:propionate (Ac:Pr; P < 0.0001), acetate (P < 0.0001), and propionate (P < 0.0001) demonstrating that total VFA, acetate, and Ac:Pr all increased throughout the trial, while propionate decreased. These results indicate that SB can be a potential alternative feed at this stage of production as it does not negatively impact health or production, but does affect the rumen pH and proportion of some VFA.

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.

Anabolic implants alter abundance of mRNA involved in muscle growth, metabolism, and inflammation in the longissimus of Angus steers in the feedlot

The majority of beef cattle in the United States often receive at least one anabolic implant resulting in improved growth, feed efficiency, and environmental and economic sustainability. However, the physiological and molecular mechanisms through which anabolic implants increase skeletal muscle growth of beef cattle remain elusive. The objective of this study was to identify transcriptional changes occurring in skeletal muscle of steers receiving anabolic implants containing different steroid hormones. Forty-eight steers were stratified by weight into 1 of 4 (n = 12/treatment) implant treatment groups: (1) estradiol (ImpE2; 25.7 mg E2; Compudose, Elanco Animal Health, Greenfield, IN), (2) trenbolone acetate (ImpTBA; 200 mg TBA; Finaplix-H, Merck Animal Health, Madison, NJ), (3) combination (ImpETBA; 120 mg TBA + 24 mg E2; Revalor-S, Merck Animal Health), or (4) no implant (CON). Skeletal muscle biopsies were taken from the longissimus 2 and 10 d post-implantation. The mRNA abundance of 94 genes associated with skeletal muscle growth was examined. At 10 d post-implantation, steers receiving ImpETBA had greater (P = 0.02) myoblast differentiation factor 1 transcript abundance than CON. Citrate synthase abundance was increased (P = 0.04) in ImpETBA steers compared to CON steers. In ImpE2 steers 10 d post-implantation, muscle RING finger protein 1 decreased (P = 0.05) compared to CON steers, and forkhead box protein O4 decreased (P = 0.05) in ImpETBA steers compared to CON steers. Interleukin-6 abundance tended to be increased (P = 0.09) in ImpE2 steers compared to both ImpETBA and CON steers. Furthermore, interleukin-10 mRNA abundance tended to be increased (P = 0.06) in ImpTBA steers compared to ImpETBA steers. Leptin receptor abundance was reduced (P = 0.01) in both ImpE2 and ImpTBA steers when compared to CON steers. Abundance of phosphodiesterase 4B was increased (P = 0.04) in ImpTBA steers compared to CON steers 2 d post-implantation. Taken together, the results of this research demonstrate that estradiol increases skeletal muscle growth via pathways related to nutrient partitioning and mitochondria function, while trenbolone acetate improves steer skeletal muscle growth via pathways related to muscle growth.

Cattle breed type and anabolic implants impact calpastatin expression and abundance of mRNA associated with protein turnover in the longissimus thoracis of feedlot steers

Two methods that the beef cattle industry can use to improve efficiency, sustainability, and economic viability are growth promotants and crossbreeding cattle of different breed types. In the United States, over 90% of cattle receive an anabolic implant at some point during production resulting in an overall increase in skeletal muscle growth. Recent research suggests that the two main cattle breed types, Bos indicus and Bos taurus, respond differently to anabolic implants. The objective of this study was to characterize changes that occur in skeletal muscle following implanting in Bos indicus influenced steers or Bos taurus steers. Twenty steers were stratified by initial weight in a 2 × 2 factorial design examining two different breeds: Angus (AN; n = 10) or Santa Gertrudis influenced (SG; n = 10), and two implant strategies: no implant (CON; n = 10) or a combined implant containing 120 mg TBA and 24 mg E2 (IMP; n = 10; Revalor-S, Merck Animal Health). Skeletal muscle biopsies were taken from the longissimus thoracis (LT) 2 and 10 d post-implantation. The mRNA abundance of 24 genes associated with skeletal muscle growth were examined, as well as the protein expression of µ-calpain and calpastatin. Succinate dehydrogenase mRNA abundance was impacted (P = 0.05) by a breed × treatment interaction 2 d post-implanting, with SG-CON having a greater increased abundance than all other steers. A tendency for a breed × treatment interaction was observed for calpain-6 mRNA (P = 0.07), with SG-CON having greater abundance than AN-CON and SG-IMP. Additionally, calpastatin protein expression was altered (P = 0.01) by a breed × treatment interaction, with SG-CON and SG-IMP steers having increased expression (P = 0.01) compared with AN-CON steers. At 2 d post-implanting, a breed × treatment interaction was observed with SG-CON steers having greater (P = 0.05) mRNA abundance of mitogen-activated protein kinase compared with AN-CON steers. Furthermore, breed affected (P = 0.05) calpastatin abundance with AN steers having increased (P = 0.05) abundance 2 d post-implanting compared with SG steers. Meanwhile, implants tended to affect (P = 0.09) muscle RING finger protein-1 mRNA abundance, with CON steers having increased (P = 0.09) abundance compared with that of IMP steers. These findings suggest that cattle breed type and anabolic implants impact calpastatin expression and mRNA abundance associated with protein turnover in the LT of feedlot steers 2 and 10 d post-implantation.

Comparing net returns in the feedlot: Bos Taurus vs. Bos Indicus influenced steers with varying anabolic implant intensity

There are two main beef cattle breed types: Bos Taurus (BT) and Bos Indicus (BI). Past research has demonstrated various expected differences in growth, temperament, feeding behavior, and carcass characteristics between these breed types when administered varying levels of anabolic implant. However, little is known about the differences in expected economic returns between these cattle types. The objective of this research is to simulate and compare the expected net returns of BT, Angus (AN) steers and BI influenced, Santa Gertrudis (SG) steers, with moderate or high intensity levels of implants relative to a control with no implant. The animal performance and carcass data for this economic analysis was provided from a recent feeding experiment of AN and SG influenced steers. In the experiment, sixty steers were stratified by weight and breed in a 2 × 3 factorial design examining the two different breeds: AN (N = 38) or SG influenced (N = 22), and three implant strategies: no implant (N = 20), a moderate intensity implant protocol (d0 implant: Revalor-G, d56 implant: Revalor-IS, d112 implant: Revalor-S; n=20), or a high intensity implant protocol (d0 implant: Revalor-IS, d56 implant: Revalor-S, d112 implant: Revalor-200; N = 20). The steers performance and carcass data were used together with publicly available price and input costs data in the simulation of net returns per animal for each of the treatment groups. Results demonstrated that both moderate and high intensity implanted BT steers have higher expected net return (US$78.70/hd. and US$75.84/hd., respectively) compared to BI moderate and high intensity implanted steers (US$47.03/hd. and $6.98/hd., respectively). Stochastic efficiency analysis with respect to a function demonstrated when certainty equivalent values are constrained to those ≥US$0, only the moderate implanted BT steers would be included in the efficient set.

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

Simple Summary

Though anabolic implants are commonly utilized in U.S. cattle production, comparisons between hormone type and content of different implants and the effects on growth and trace mineral stores is limited. The objective of this study was to evaluate the effects of anabolic implants varying in hormone type and concentration on growth, carcass characteristics, and trace mineral concentrations in Angus steers. Cattle administered an estradiol only implant did not experience differences in growth compared to non-implanted controls. However, cattle implanted with a trenbolone acetate only implant or a combined (estradiol and trenbolone acetate) implant experienced improvements in growth and changes in plasma and liver trace mineral concentrations. Greatest differences in growth and trace mineral concentrations were observed in steers administered the combination implant compared to non-implanted controls. These data suggest hormone type and concentration influence implant-induced growth and changes in plasma and liver trace mineral concentrations.

Abstract

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.