Feed preference of grower ostriches consuming diets differing in Lupinus angustifolius inclusion levels
Feed costs contribute the largest proportion of the input costs of slaughter birds in an intensive ostrich production unit. Alternative, cheaper feedstuffs, such as lupins (sweet and bitter cultivars), were therefore evaluated to determine the optimal lupin inclusion level in ostrich rations without affecting feed preference and intake. Sixty South African Black ostriches were randomly divided into ten paddocks of six birds per paddock. Three trials, with five different experimental diets, were conducted to investigate the diet preference of grower ostriches in a free-choice system. Feed and water were supplied ad libitum. The position of the diets in the successive paddocks was varied by rotating the five feed troughs in a clockwise direction, but within each paddock the position of each feeder and diet stayed the same throughout the three trials. In the first two trials, sweet (trial 1) or bitter (trial 2) lupins replaced soybean oilcake meal to have 0, 7.5, 15, 22.5, and 30% lupin inclusion levels in the diet. In trial 3 the soybean oilcake meal was replaced with either sweet or bitter lupins to have dietary inclusion levels as follows: 0% lupins, 15% sweet, 15% bitter, 30% sweet, or 30% bitter. The daily intake per group for each diet was monitored over a period of five days each. The average initial body weight of the birds was 73.6 ± 0.5 kg. No interaction was found between day and diet for the three trials and dry matter intake (DMI) did not differ between the five treatments for any of the three trials. In the second trial the birds tended to show a preference for the 7.5% bitter lupin inclusion level and discriminated against the 15% and 30% bitter lupin inclusion levels. Regression analysis of DMI on lupin inclusion rates revealed no significant trends. In conclusion, the study revealed that soybean oilcake meal can be replaced in the diets of grower ostriches by sweet lupin inclusion levels up to 30%, without any significant detrimental effect on diet preference and feed intake.
Keywords: Alkaloids, dry matter intake, feed palatability, lupins, visual appearance of the feed