Calf Performance and Female Reproductive Traits in Second Generation Reciprocal Nellore-Angus Crosses
Abstract
The objectives of this study were to analyze calf performance traits and female reproductive traits in reciprocal F2 Nellore-Angus calves (n = 539) born 2010-2015 and calves out of these F2 females through 4 yr age (n = 443) born 2012-2018. The F2 animals were produced using reciprocal F1 Nellore-Angus sires and dams (AN and NA, sire breed is listed first followed by dam breed). The F2 breed types included ANAN, ANNA, NAAN, and NANA where the first two letters are the animal’s sire type and the third and fourth are its dam type (i.e., ANNA were sired by F1 AN bulls and out of F1 NA cows). Calf performance traits were analyzed using mixed models and female reproductive traits were analyzed through PROC GLIMMIX in SAS. Dam type influenced Julian birth date (P < 0.05) in the F2 calves with those out of AN cows being born earlier than those out of NA cows. Sire type and dam type affected birth weight (P < 0.05) but not weaning weight of the F2 calves. The interaction between sire type and dam type accounted for weaning weight differences (P = 0.038). Sire type also accounted for important variation in the calf sex distribution at birth among F2 calves (P < 0.005). Percent male at birth and weaning among the F2 calves exceeded the expected ratio for calves with NA sires, calves out of AN dams, and NAAN and NANA calves (P ≤ 0.05). The opposite trend appeared in calves from F2 females with calves out of NA-sired dams and NANA dams having more females at birth and weaning (P ≤ 0.05). The sole significant breed effect for calves out of F2 females was sire type × dam type × sex for weaning weight (P = 0.010) where only among calves from ANNA and NANA dams were males heavier than females. These results suggest that some of the calf weight reciprocal differences typically observed among F1 Bos indicus-Bos taurus crosses can continue into later generations. Reciprocal breed effects were insignificant for reproductive traits in young F2 Nellore-Angus females.
Subject
reciprocalsecond genreration
calf performance
female performance
nellore
angus
sex ratio
crossbred
Citation
Mickey, Dana Marie (2021). Calf Performance and Female Reproductive Traits in Second Generation Reciprocal Nellore-Angus Crosses. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /195141.