African Mutton Merino ewes as supplementary feed during late pregnancy and lactation, while grazing wheat stubble at 2 ewes/ha during 1986 and 1987. Blood glucose, urea, calcium, magnesium and zinc levels of the ewes were monitored in 1986 only. Ewes received supplementary feed at 750 g/ewe/d for 16 weeks in 1986, and 550 g/ewe/d for 10 weeks and 750 g/ewe/d for the subsequent f weeks in 1987. The crude protein (CP) content of the oats was increased from 9,8% to 12,5% (EOAT) and 15,8% (NH30AT) in the first year and from 8,7% to 11,7% (EOAT) and 13,0% (NH30AT) in the second year. Ewes which received EOAT and NH30AT grain as supplement, tended in both years to maintain higher mean live masses (P ≤ 0.1) during lactation than ewes which received OAT grain. This improvement was probably due to the higher CP and energy content of the treated grain. Providing ewes with NH30AT grain as a supplement, significantly (P ≤ 0.05) improved 100-day lamb weaning mass and average daily gain (ADG) from birth to weaning by ca 19%, in comparison to the OAT and EOAT treatments in 1986. In 1987, weaning mass and preweaning growth of lambs in the NH30AT treatment group were improved by ca 14% in comparison to the EOAT treatment. Lambs from ewes consuming the NH30AT supplement were 7,3% heavier (P ≤0.05) at weaning than their contemporaries in the OAT group, but ADG figures for these two treatments did not differ (P ≤ 0.05). The tendency towards better performance of sheep in the NH30AT group could be related to differences in blood glucose levels between groups, which. suggests that an improved energy metabolism may be involved. The concentrations of plasma calcium, magnesium and zinc of ewes were unaffected by treatment and within ranges specified in the literature. It was concluded from the study that thermal ammoniation of oat grain led to improved utilization thereof, although the economical application of the procedure has to be elucidated. Satisfactory results in ewe live mass and lamb growth rate were also achieved with plain and urea-enriched oat grain.
Keywords: Blood metabolites, blood minerals, ewes, lamb growth rate, oat grain, stubble grazing, supplementation, thermal ammoniation