Abstract

SANTOS, S.F. et al. Effect of the castor bean hulls in the dairy goat diet on production, content and fat acid profile of milk. Arch. zootec. [online]. 2011, vol.60, n.229, pp.113-122. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922011000100013.

The aim of this work was to evaluate the effect of substitution levels of the Tifton 85 hay by castor bean hulls in diets for dairy goats on the yield, chemical composition and fatty acids profile of milk. Eight Anglo-Nubian female goats, breed, with average weight of 45 kg were used. The animals were allocated in stalls and distributed in a double 4x4 latin square experimental design. The treatments consisted of three levels of substitution of the Tifton 85 hay by castor bean hulls as roughage food (0, 33, 67 and 100%) maintaining the roughage:concentrate ratio of 50:50. Each experimental period had a duration of 21 days, being 14 days of adaptation and seven days of data collection. There was a decrease in production when the castor hulls were included in diet, and two diets containing the highest levels of inclusion of the castor bean hulls did not differ between themselves. For milk chemical composition, there was no effect when Tifton 85 hay was substituted by castor bean hulls on the crude protein, minerals, lactose and total dry extract. The fat milk level was increased when the castor bean hulls substituted the Tifton 85 hay in the levels 67 and 100%, but it caused no change in milk density, whose average density was 1031. The substitution of Tifton 85 hay by castor bean hulls promoted effect on the fatty acids concentration. Was found significant effect, for fatty acid concentration, on the levels of miristic acid (C_{14: 0}), linoelaidic acid (C_{18: 2n6t}), conjugated linoleic acid (CLA _9t11) and on the profile of saturated (AGSAT), polyunsaturated (AGPOL) and essential fatty acids (AGESS) (p<0.05). There was no effect of treatments on unsaturated, short chain, long chain and monounsaturated fatty acids (p>0.05). The substitution of Tifton 85 hay by castor bean hulls reduced the atherogenicity index (AI) of the diet. The castor bean hulls can replace the Tifton 85 hay in up to 33% in diet of dairy goats. This substitution can be viable when the goal is to have goat milk with better nutritional characteristics.

Keywords : Byproduct; Fiber; Small ruminant; Ricinus communis.

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