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Title: BODY COMPOSITION AND ENERGY UTILIZATION BY STEERS OF DIVERSE GENOTYPES FED A HIGH-CONCENTRATE DIET DURING THE FINISHING PERIOD: II. ANGUS, BORAN, BRAHMAN, HEREFORD, AND TULI SIRES.

Author
item Ferrell, Calvin
item Jenkins, Thomas

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Objectives of the study were to determine the influence of diverse sire breeds, including Angus, Boran, Brahman, Hereford, or Tuli on body composition, composition of gain and energy utilization of crossbred steers during the finishing period. Differences among steers of diverse sire breeds in body weight, composition, and composition of gain were noted, as were differences in maintenance requirements and efficiencies of energy use for gain. However, the hypothesis that tropically adapted cattle have lower energy requirements for maintenance than those adapted to temperate environments was not supported by results obtained when a high concentrate diet was fed during the winter in a temperate environment. The results of these studies indicate the relationship of gain to intake was not linear over the range in intakes observed in this study, but followed the concept of diminishing returns. The implication of this observation is that maximum efficiency in finishing feedlot cattle may occur at less than maximum intake.

Technical Abstract: Objectives of the study were to determine the influence of diverse sire breeds, including Angus (A), Boran (BO), Brahman (BR), Hereford (H), or Tuli (T) on body composition, composition of gain and energy utilization of crossbred steers during the finishing period. Beginning at about 300 kg, 96 steers were adjusted to a high corn diet and individual feeding. Steers were assigned, by sire breed (S), to be killed as an initial slaughter group (ISG) or fed either a limited amount or ad libitum for 140 d. Organ weights, carcass traits, and body composition were determined. The statistical model included S, treatment (Trt), and S x Trt. Empty body, carcass, offal, and live weights of ISG steers differed (P < .05), but percentage of composition of carcass and empty body were similar (P > .25) among sire breeds. Feed intake was least for BO- and T-, intermediate for BR and H, and greatest for A-sired steers, when fed ad libitum, but similar among sire breeds when limit-fed. When fed ad libitum, mean rates of weight, fat, and energy gains were similar for A , H , and BR sired steers, but less (P < .01) for BO and T. Rates of protein or water gains did not differ among sire breeds (P > .12). Rates of water, fat, and protein increased linearly with increased rate of BW gain, but relationships differed (P < .05) among sire breeds. Evaluation by nonlinear regression indicated heat production increased exponentially and energy gain increased asymptotically as feed intake increased above maintenance.