Supplementary feeding of young Merino sheep, grazing wheat stubble, with different amounts of lupin, oat or barley grain

Abstract

We examined the effect on liveweight change and wool growth of 3 grain supplements: lupins, oats and barley, fed at different levels to grazing Merinos. The animals (approx. 9 months of age, mean weight 29.3 kg) grazed wheat stubble (10 sheep/ha) from January to May and each supplement was fed at 0, 150, 300,450, 600, and 750 g/sheep.day (given twice per week). The digestibility of the stubble was high (stem 45%, leaf 58%) in February and decreased by May (stem 42%, leaf 49%). The unsupplemented animals received no supplementation until 1 May, when they reached a weight of 26.5 kg. The liveweight of the supplemented animals increased in relation to the amount of each supplement given. The conversion (kg supplement fed per kg liveweight gain, was 3.64 for lupins compared with 4.93 and 5.21 for the oats and barley respectively. There was an increase in the clean fleece weight (Y, kg) (November shearing) with increasing levels of each supplement (X, kg grain/sheep.day) described by the following equation; Y= 2.65 + 2.26X- 1,343, but there were no differences associated with the type of grain. As the level of supplement intake increased from 0 to 750 g/day, fibre diameter increased (P< 0.001) from 18.6 to 2 1.1 km, staple length increased (P < 0.01) from 73.5 to 86.7 mm and staple breaking force increased (P<0.05) from 17.4 to 26.1 N/ktex. There was no effect of type of supplement on parameters of wool quality. With all supplements there was an apparent carry-over effect of the summer-autumn feeding on wool growth during the winter period. For each additional 1 g of wool grown during the supplementary feeding period, approximately 1.4 g were measured in the final fleece weight.