The evaluation of lupins (Lupinus angustifolius) as alternative protein source in ostrich (Struthio camelus var. domesticus) diets

[摘要] ENGLISH ABSTRACT: In an intensive ostrich production unit, one of the highest cost components is nutrition, contributing ca. 75% to the total input costs. Energy and protein are the two most important and abundant nutrients found in a balanced diet, with the protein component being the most expensive per unit weight. This study was conducted to evaluate the inclusion of lupins (Lupinus angustifolius) as an alternative protein source to soybean oilcake meal in ostrich (Struthio camelus var. domesticus) diets.In the first study (chapter 3) production performance and slaughter traits were studied at different dietary lupin inclusion levels that replaced soybean oilcake meal. There were five dietary treatments with three replications of between 15 – 17 chicks each. The chicks all received the same pre-starter diet. Five iso-nutritional diets were formulated for each feeding phase (starter, grower and finisher) using Mixit2+ software according to specifications set out for each of the different feeding phases Within each feeding phase these diets contained either soybean oilcake meal (control diet; 0LD) or sweet lupins (alternative protein source; diets 25LD, 50LD, 75LD and 100LD) as the primary protein source. The 100 lupin diet (LD) was formulated to include the maximum amount of sweet lupins according to the specifications for the specific species and the feeding phase. The maximum amount of lupins included in the 100LD therefore differs between the three feeding phases. The remaining three diets were formulated by mixing the diets to determine the gradual increase in lupins in the diets from 0LD up to 100LD. Soybean oilcake meal was thus gradually replaced by sweet lupins in the following ratios: 100:0 (0LD), 75:25 (25LD), 50:50 (50LD), 25:75 (75LD) and 0:100 (100LD) to make up the five dietary treatments for each feeding phase. No differences were found in the live weight of the birds at the end of each feeding phase or in the dry matter intake (DMI), average daily gain (ADG) or feed conversion ratio (FCR). The end weight (P = 0.07) and ADG (P = 0.09) for the starter phase tended to be higher for the birds on the 75LD. Birds fed the 50LD and 75LD tended (P = 0.08) to have the heaviest cold carcass weights, although dressing percentages did not differ. Birds receiving the 50LD diet had somewhat heavier (P = 0.05) thighs than those on the other diets. No differences were found for the weight of the big drum muscles of the birds. It was concluded that soybean oilcake meal can be replaced by sweet lupins in starter diets by up to 15% lupin inclusion in the diet (75LD) and in grower and finisher diets by up to 30% lupin inclusion in diet (100LD) without any significant detrimental effect on the production and slaughter traits.The second study (chapter 4) evaluated the three primary ostrich products (leather, meat and feathers) to clarify whether the lupin inclusion levels had any effect on these products. Birds used in this study were the same birds as described in chapter 1. No differences were found for the marketable feather classes and measured leather traits, but the leather was thicker (P < 0.05) for birds fed the 25LD. This corresponds with the heavier slaughter weight of the birds on the 25LD, although this was not significant. No differences were found in the chemical composition of the meat, apart from a higher (P < 0.05) intra-muscular fat content being found for birds on the 50LD. It can be concluded that the sweet lupin inclusion levels evaluated in this study had little influence on the leather traits, chemical composition of the meat of the birds measured (ten birds per treatment were selected around the median for chemical analysis of their meat) and the feather classes.In the third study (chapter 5), 60 South African Black growing ostriches were randomly divided into 10 paddocks with six birds per paddock. Three trials with five experimental diets per trial were conducted to investigate the effect of sweet and/or bitter lupins on the feed preference of growing ostriches in a free-choice system. In Trial 1 (sweet) and Trial 2 (bitter), lupins replaced soybean oilcake meal in a step-wise manner for inclusion levels of 0%, 7.5%, 15%, 22.5% and 30%. In Trial 3, the soybean oilcake meal was replaced with 0%, 15% sweet, 15% bitter, 30% sweet and 30% bitter lupin inclusion levels. The position of the feeders containing each diet in successive paddocks changed by rotating the five feed troughs in a clockwise direction, but within each paddock the specific position of each feeder and diet stayed the same throughout the three trials. No interaction was found between day and diet for the three trials. The DMI per diet did not differ between the five treatments in any of the three trials. However, in trial 2 the birds showed a tendency (P = 0.11) to prefer the 7.5% bitter lupin diet to the 15% and 30% diets. The results showed that soybean oilcake meal can be replaced in the diets of growing ostriches by sweet lupin inclusion of up to 30% without any significant detrimental effect on feed preference and intake. The tendency (P = 0.11) of the birds to discriminate to some extend against the 15% and 30% bitter lupin diets may warrant further research.This study found that lupins can be used without compromising growth or product quality in ostriches, making them a viable economic alternative.

[发布机构] Stellenbosch University