Information on feather and skin growth is important for the development of mathematical optimisation nutritional models for ostriches. Ostriches (n = 65) were subjected to a four-stage formulated growth diet programme (pre-starter, starter, grower and finisher), with declining protein and energy content. Nine birds were weighed, stunned, exsanguinated, defeathered, skinned and eviscerated at 1, 54, 84, 104, 115, 132 and 287 days of age. Feathers from four pre-selected locations on the body were harvested and weighed. The wet skin weight, wet unstretched skin size and wet unstretched crown size were measured at each slaughter stage. The live weight, feather and skin yields of the birds increased with age at slaughter, as did feather shaft diameter. Prediction models were developed to estimate the yield of the skin in terms of live weight and of empty body protein weight to aid in diet formulation. The allometry of feather growth was determined from total feather weight, as the maturation rates of the feathers differ from that of the ostrich body. Results from this study will aid in setting up a mathematical optimisation nutritional model for ostriches.
Full-fat canola seed (FFCS) is a locally produced alternative protein source that has potential for inclusion in the diet of ostriches. Chicks aged 84 days and weighing 24.7 ± 0.36 kg were fed five iso-nutritional diets with varying levels of FFCS. Birds were fed until slaughter at 309 days old (93.2 ± 1.82 kg). In each feeding phase, FFCS replaced soybean oilcake meal incrementally (0%, 25%, 50%, 75% and 100% of protein source). Dry matter intake (DMI) during the grower phase was lowest (1.52 kg/bird/day) for the 100%FFCS diet. Birds on the 100%FFCS also showed a 34% slower growth rate (average daily gain of 152.0 g/bird/day) compared to the other four diets (average growth rate of 230 g/bird/day) during the grower phase. The 0%FFCS (236.2 g/bird/day) and 50%FFCS (267.8 g/bird/day) diets resulted in a higher ADG. End weights during the grower phase for 0%FFCS, 25%FFCS, 50%FFCS and 75%FFCS (74.8, 72.2, 76.8, and 72.5 kg, respectively) did not differ significantly. The 100%FFCS resulted in a lower end weight (67.4 kg) for the growth phase, when compared to the 0%FFCS and 50%FFCS diets. For the overall trial period, the only differences were in ADG, with the 0%, 50% and 75%FFCS replacement diets showing the fastest growth. Fat pad weight was the only slaughter trait that revealed differences between diets, with 50%FFCS resulting in the heaviest fat pad weight. A maximum of 20.6% inclusion of FFCS should be used in diets in the grower phase, although in the other phases, FFCS could be included up to the maximum level evaluated (100% replacement of soybean oilcake meal) without detrimental effects on production parameters.Keywords: Average daily gain, Brassica napus, dressing percentage, dry matter intake, feed conversion ratio, glucosinolates, Struthio camelus
The largest expense of an intensive ostrich production unit is feed cost (ca.75%). Protein makes up a great portion of feed for monogastric animals and this expense can be lowered by utilizing locally produced feedstuffs such as full-fat canola, although it is not clear whether ostriches will readily consume full-fat canola because of its anti-nutritional and other known factors. To evaluate the feeding preference of ostriches towards full-fat canola, 60 South African Black ostriches (82.2 ± 1.06 kg in live weight) were placed in 10 camps of six birds per camp. Each camp had five identical feed troughs containing diets in which full-fat canola seed (FFCS) incrementally (0, 25, 50, 75 and 100% of protein source) replaced the soybean oilcake meal (9.8% of the total diet composition in control diet was soybean oilcake meal and full-fat canola was included up to 27.5% of the total diet) as protein source. Dry matter intake (DMI) was measured daily and feed colour characteristics were measured, based on L*, a* and b* colour attributes. Only the 25%FFCS showed a higher DMI (817.38 ± 81.98 g/bird/day) and percentage DMI (~29.53%) than the other diets, with an average DMI of 488.8 g/bird/day) and percentage DMI of 17.62%. Although the 0%FFCS, 50%FFCS and 75%FFCS had a lighter colour than the 25%FFCS and 100%FFCS and the b* colour parameter for 100%FFCS was lower than the rest, it is believed that these differences had no effect on DMI. Based on the results of this study, diets with up to 27.5% full-fat canola seeds had no detrimental effect on feed intake of finishing ostriches. Birds prefer diets with a combination of 6.9% full-fat canola seed and 7.4% soybean oilcake meal.
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