PSXVII-24 Relationships among feed efficiency performance and value of bulls in the Florida Bull Test.

摘要

Eight hundred and twenty nine bulls of various breeds were enrolled in the Florida Bull Test at the University of Florida’s North Florida Research and Education Center (NFREC) over a period of 9 years between 2008 and 2016. Bulls (8 to 12 mo of age) were housed at the NFREC Feed Efficiency Facility (FEF) for 56 d where daily feed intake was monitored using the GrowSafe system. A diet was fed to achieve a target ADG of 1.6 kg. After removal from the FEF, bulls were placed in 1.32-ha pastures for the remaining 56 d of the test. Annually, the bulls that qualified were able to be sold at the Florida Bull Test Sale. Feed efficiency characteristics and performance traits were evaluated throughout the test. Average daily gain differed (P<0.001) by year and ranged from 1.32 to 1.65 kg. A difference (P<0.001) was detected in weight per d of age (WDA) among years and ranged from 1.29 to 1.37 kg. In addition, average sale price differed (P<0.001) by year and ranged from $1,477.00 to $4,585.71. Of the 2 breeds that were consistently represented over the 9 years (Angus and Simmental), a breed × year interaction (P=0.004) was observed on sale price. Correlations (P<0.001) were detected between sale price and ADG (r=0.238), WDA (r=0.314), index ratio (r=0.297), final body weight (BW; r=0.457), frame score (r=0.199), and scrotal circumference (SC; r=0.345). Scrotal circumference was correlated to final BW (r=0.522, P<0.001). Residual feed intake (RFI) for the first 28 d was correlated to 56-d RFI (r=0.842, P<0.001). Moreover, WDA was correlated to average feed intake (r=0.541, P<0.001). As expected, the sale price of bulls differed by year depending on the cattle market. In addition, in order of priority, sale price was correlated to BW, SC, WDA, index ratio, ADG, and frame score.