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Associations of Feed Efficiency with Performance, Feeding Behavior, Carcass Quality, and Fertility Traits in Growing Cattle
Abstract
The objectives of this study were to evaluate the effects of the selection of bulls for feed efficiency on progeny growth performance, feed efficiency, feeding behavior patterns, carcass composition, and fertility. In study 1, 373 Angus steers sired by bulls divergently selected for residual gain (RG) over a 6-year period were used to compare growth performance, feed efficiency, feeding behavior patterns, and carcass characteristics. Selected Angus sires were either high or low for RG expected progeny differences (EPD) and either high or breed average (AVG) for marbling (MB) EPDs. A 70-day feeding evaluation trial utilizing electronic feed bunks was completed to determine dry-matter intake, average daily gain, residual feed intake, and feeding behavior. After slaughter, postmortem carcass data was collected. The effects of RG and MB sire EPD classification on the growth performance, feed efficiency, feeding behavior, and carcass composition traits in their Angus steer progeny was analyzed.
High RG sired steers had greater (P = 0.017) HCW than their low RG sired contemporaries along with greater (P = 0.016) LMA and lesser (P = 0.016) percentages of IMF. Steers sired by average MB bulls had 4% greater (P = 0.009) ADG per day than high MB sired steers. High MB sired steers had lesser (P = 0.012) G:F than their average MB sired contemporaries.
In study 2, performance, feed efficiency, carcass composition, feeding behavior, and fertility traits were measured in 1,013 Angus, SimAngus, and Simmental bulls (12 trials). The bulls were grouped into low, medium, and high RFI groups to evaluate the effect of their RFI classification on these response variables. Low RFI bulls consumed 27.6% less (P < 0.001) feed than the high RFI bulls and 12.3% less than the medium RFI bulls. Low RFI bulls had 21.6% and 12.1% greater G:F than high and medium RFI bulls, respectively with no differences observed in final BW or ADG. The differences in DMI manifested in differences in RFI, RFIc, and RG. These studies suggest that RFI is a more advantageous selection criterion than RG, as it is more closely associated with growth performance, feed efficiency and feeding behavior traits.
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Citation
Linyear, Jerome Scott (2023). Associations of Feed Efficiency with Performance, Feeding Behavior, Carcass Quality, and Fertility Traits in Growing Cattle. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /203049.