Ovulation in ewes given formaldehyde-treated or untreated casein in maintenance-energy rations

Abstract

Forty-six Border Leicester ewes and 40 Dorset Horn ewes were individually fed in pens, for a period of mean length 25 days, with amounts of pelleted lucerne and barley that approximately met their energy requirements for maintenance, and contained 14.75% crude protein in the dry matter. Maintenance feeding continued on average for a further 23 days until the ewes were mated, but during this period individual daily rations for one half of each breed group contained 60 g casein that had been treated with formaldehyde; rations for the other ewes were virtually identical except that the casein was untreated. Measurements of blood urea nitrogen, plasma amino acids, and wool growth on the Dorset Horn ewes indicated that the treated casein diet provided the ewes with greater quantities of amino acids than did the untreated diet.

The ovaries of all ewes were examined by laparotomy after mating. The mean number of corpora lutea per ewe was 1.6 and did not differ significantly between casein diets, nor did the mean number of ovarian follicles, 1.6, or follicle size. There were also no differences in the numbers of ewes that failed to lamb, or bore single or twin lambs.