Three hundred pregnant beef cows between 35 and 125 days of gestation were scanned ultrasonically and their calving dates were predicted from measurements of fetal parts. The mean difference between the actual and predicted calving dates was 0.9 day with a standard deviation of 9.0 days. The accuracy and precision of the prediction of calving date were sufficient to be of benefit in the management of cows in late pregnancy and at calving.

Ewe live iveights were recorded 4 weeks prior to mating, at the beginning of mating and 22 to 23 days later over a period of 3 years in a flock of some 300 breeding ewes comprising approximately equal numbers of Australian Merino, Ideal (Polwarth), Merilin and Corriedale breeds in a pastorally based grazing system in Uruguay. Multiple-bearing ewes were generally heavier than single-bearing ewes which in turn were heavier than ewes which did not conceive, these differences being greatest in 3-and 4-year-old ewes (i.e. in their second and third breeding seasons). Body condition scores of non-pregnant ewes were lower than those of pregnant ewes, particularly in the 3and 4-year-old age groups. Ewe live weights achieved prior to, during and at the end of the mating period and the body condition score achieved 4 weeks prior to mating all had significant influences on the number of lambs born (P < 0-01) but there were no significant effects of changes in either live weight or body condition over the 4 weeks prior to mating or during the mating period. The effect of body condition score over the range from 2-0 to 4-0 was to increase the proportions of single-and multiple-bearing ewes and to decrease the proportion of non-pregnant ewes such that the number of lambs born per ewe mated increased from 0-94 to 1-38. Fleece weights differed significantly between breeds, Corriedales having the heaviest fleeces and Merilins the lightest (4-26 and 3-22 kg respectively). Wool production was also significantly and positively affected by age (P < 0-01) and by ewe weight at mating (P < 0-01). The results demonstrate the importance of giving preferential nutritional treatment to younger ewes to ensure a satisfactory subsequent lambing performance and improved wool production.

The development of cobalt deficiency was studied in 30 Scottish Blackface lambs grazing pasture on a soil containing 0-17 ppm cobalt. By the end of an eight-week period 50 per cent of lambs were subjectively appraised as showing signs of cobalt deficiency. After a further period lasting four weeks, during which three groups of lambs were studied (one group, least affected by cobalt deficiency, acted as control, the second received a single cobalt bullet and the third received oral doses of 200 mg cobalt chloride at the beginning of the period and three weeks later). Mean urinary formiminoglutamic acid (FIGLU) concentrations were inversely related to serum vitamin B12 concentrations and increased from 0-08 to 0-20 mumole per ml in group 1, and decreased to virtually zero within one week of treatment in groups 2 and 3. The use of serum vitamin B12 and urinary FIGLU concentrations in the diagnosis of cobalt deficiency in sheep are discussed.

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