Genotype x environment interactions in preweaning traits of purebred and reciprocal cross Angus and Brahman calves on common bermudagrass and endophyte-infected tall fescue pastures.
Preweaning data on 486 Angus, Brahman, and reciprocal cross calves (AB, BA) managed on common bermudagrass or endophyte-infected tall fescue were used to evaluate the interactions of forage type and sex of calf with direct effects, individual heterosis, and maternal effects. Calves were spring-born in 1988, 1989, 1990, and 1991 to five sires of each breed. Male calves were castrated at birth, and calves were not creep-fed. Average values of heterosis for birth weight, 205-d weight, weaning hip height, and weaning weight:height ratio (WT/HT) were important (P < .01) and consistent across forage environment. Heterosis for birth weight was larger in bull calves than in heifer calves (P < .05), whereas heterosis for other preweaning traits were consistent across sex of calf. Average maternal effects for WT/HT (P < .10) were important and consistent across forage environment. Maternal effects for birth weight were larger with bull calves than with heifer calves (P < .01). Maternal effects for weaning hip height favored the Angus dam managed on bermudagrass (P < .05) but not managed on fescue. A similar but nonsignificant trend occurred in maternal effects for 205-d weight. Direct effects for birth weight were larger in bull calves than in heifer calves (P < .01). Direct effects for weaning height were larger in calves managed on bermudagrass than in calves managed on tall fescue (P < .07). A similar but nonsignificant trend was evident in direct effects for 205-d weight. Direct effects for WT/HT were relatively small and unimportant.(ABSTRACT TRUNCATED AT 250 WORDS)
Brown
M A
MA
South Central Family Farm Research Center, ARS, USDA, Booneville, AR.
Tharel
L M
LM
Brown
A H
AH
Jackson
W G
WG
Miesner
J R
JR
D000704:Analysis of Variance; D000821:Animal Feed; D000818:Animals; D001724:Birth Weight / Q000235:genetics; D001947:Breeding; D002417:Cattle / Q000235:genetics / Q000254:growth & development*; D005260:Female; D005516:Food Microbiology; D005658:Fungi / Q000254:growth & development; D005838:Genotype; D006823:Hybrid Vigor; D008297:Male; D006109:Poaceae / Q000382:microbiology; D012737:Sex Factors; D014886:Weaning; D015430:Weight Gain