ABSTRACT
Data from farmer-owned herds and from experimental matings supported monofactorial recessive inheritance of rectovaginal constriction in US Jersey cattle. Kempthorne's population genetics model of a recessive trait involving only male selection was extended to include mutation and converted to selection of females only. Computer analyses with that model estimate slow decline in the frequency of the gene for rectovaginal constriction. Practical dynamics of the disorder in a breed registering 50,000 females and 2,000 males annually are given for current conditions and after 500 generations of selection.
Subject(s)
Breeding , Cattle Diseases/genetics , Models, Genetic , Rectal Diseases/veterinary , Vaginal Diseases/veterinary , Alleles , Animals , Cattle , Female , Male , Mutation , Pedigree , Rectal Diseases/genetics , Vaginal Diseases/geneticsABSTRACT
Fifteen Jersey sires, with significant impact on the breed in the United States, were assayed for activity of uridine monophosphate (UMP) synthase. Six of these bulls were the highest ranking Jersey bulls, as July 1987, with cheese yield dollars averaging $165. These 15 bulls sired over one-third of all Jersey sons registered in 1986 and 1987 and have registered approximately 14,000 of the 37,000 lactating daughters contributing to active AI sire evaluations in 1988. These bulls represent a cross-section of the Jersey breed as they have 11 different sires; 7 different, additional maternal grandsires; and their five-generation inbreeding coefficients average 1.5%. Activity of UMP synthase was 3.14 plus or minus .24 units/ml with a range from 2.74 to 3.58 units/ml. The coefficient of variation of 7.7% was slightly less than previously reported coefficients of variation for Holsteins. All these Jersey sires had activities within normal expectations, above delimiter of two thirds of average, and none should be considered heterozygous for UMP synthase. Although this is insufficient proof of absence of the undesirable UMP synthase allele among Jerseys, it is reassuring that no heterozygotes were found among these popular Jersey sires.
Subject(s)
Carboxy-Lyases/metabolism , Cattle/metabolism , Multienzyme Complexes/metabolism , Orotate Phosphoribosyltransferase/metabolism , Orotidine-5'-Phosphate Decarboxylase/metabolism , Pentosyltransferases/metabolism , Animals , Cattle/genetics , Heterozygote , Homozygote , Male , Multienzyme Complexes/genetics , Orotate Phosphoribosyltransferase/genetics , Orotidine-5'-Phosphate Decarboxylase/geneticsABSTRACT
Two experiments examined whether vitamin B12 status of liver affects milk fat percentage or yield. In Experiment 1 B12 concentration in liver, measured at approximately 8 and 15 wk postpartum in 35 cows, was not correlated significantly with milk fat percentage or yield. In Experiment 2 twenty-two cows were fed a ratio similar to one used to depress milk fat percentage. The B12 status of 12 of these cows was enhanced by intramuscular injection of vitamin B12 while the other 10 served as controls. During wk 2 to 8 of lactation, milk fat percentages were almost identical for the two groups. A difference in milk fat yield in favor of the B12-treated group resulted from a difference in milk yield. The data do not support a recent hypothesis of the metabolic cause of milk fat depression.
Subject(s)
Lipid Metabolism , Liver/metabolism , Milk/metabolism , Vitamin B 12/metabolism , Animals , Cattle , Female , Lactation , Postpartum Period , Pregnancy , Time Factors , Vitamin B 12/pharmacologyABSTRACT
Methylmalonic acid was measured in cattle urine by decarboxylating it to propionate with sulfuric acid and heat and quantifying the propionate so formed by gas-liquid chromatography. Crystalline methylmalonic acid added to cow urine was recovered quantitatively.
