Mt. Kuhn et Rd. Shanks, ASSOCIATION OF DEFICIENCY OF URIDINE MONOPHOSPHATE SYNTHASE WITH PRODUCTION AND REPRODUCTION, Journal of dairy science, 77(2), 1994, pp. 589-597
Interaction between genotype at locus for uridine monophosphate syntha
se and parity was reexamined for 305-d mature equivalent milk and fat
production and calving interval. Three lactations for cows of known ge
notype defined two data files corresponding to different sampling proc
edures. The first data file selected by herd contained records on 23 c
ows that were deficient in activity of uridine monophosphate synthase
and on 1081 cows with normal activity; the second data file contained
records on 19 cows with deficient activity and on 17 cows with normal
activity, all daughters of bulls known to be heterozygous at the locus
for uridine monophosphate synthase. Results from the mutually exclusi
ve data files were determined independently and then pooled. Genotype
and parity interaction, tested against mean square error, was not supp
orted for any of the three traits. Mean differences of the two genotyp
es, averaged across data files, were, for first, second, and third par
ities, respectively, 360, 568, and 299 kg for milk; 6, 9, and 8 kg for
fat; and 22, 9, and 12 d for calving interval. Main effect of genotyp
e indicated a 417-kg advantage for heterozygotes but 17-d longer calvi
ng interval. The main effect of genotype on milk production adjusted f
or calving interval was 343 kg but was nonsignificant.