Studies of leptin in large domestic ruminants have been limited to measurements of gene expression because methods to measure circulating levels are not available. To develop a bovine leptin radioimmunoassay, we produced recombinant bovine leptin and used it to immunize rabbits, and to prepare bovine leptin tracer and standards. A single antiserum with sufficient affinity and titer was identifi...

Although it has long been known that there are seasonal variations in the chemical characteristics of butterfat, it has as yet not been possible to assess the relative importance of nutritional and lactational influences. Moreover, in the Northern Hemisphere the problem is further complicated by the climatic effects, which necessitate the maintenance of cows indoors during the colder months, th...

The effect of level of dietary energy and protein intake on reproductive performance was studied in 110 Finn-cross ewe lambs and in 404 Finn-cross yearling ewes during late gestation. Nitrogen metabolism was studied in 26 ewe lambs and 23 yearling ewes. Increasing digestible energy and crude protein intake for ewe lambs and yearling ewes during late gestation increased (P<.05) ewe average daily...

Lifetime (5 yr) lamb production and wool production from 207 straightbred Targhee (T) and 474 1/4 Finn-1/4 Dorset-1/2 Targhee (FDT) crossbred ewes managed in a range or farm flock system were evaluated for ewe fertility, prolificacy, ewe fleece weight, and total lamb weight weaned per ewe exposed. Data included 2,620 ewe exposures, 2,384 parturitions, 4,638 lambs born, and 3,498 lambs weaned. E...

Restriction of the conceptus to one uterine horn of the pregnant ewe results in the accumulation of fluid called uterine milk (UTM) in the contralateral horn. Two basic polypeptides, called the uterine milk proteins (UTM-proteins; Mr = 55,000 and 57,000 as determined by polyacrylamide-gel electrophoresis using sodium dodecyl sulfate), accounted for the majority of the protein in uterine milk. T...