Resumen

ERASMUS, L.J. et al. Effect of level of rumen protected CLA supplementation on milk yield and composition in Saanen goats. S. Afr. j. anim. sci. [online]. 2004, vol.34, n.5, pp.42-45. ISSN 2221-4062.

The objective of this study was to investigate the effect of level of rumen protected conjugated linoleic acid (CLA) 35 on milk yield and composition in Saanen goats. Eight multiparous goats were used in an eight animals and four periods repeated Latin square experimental design. Supplementation levels were based on 10% of the recommended level for cows. Goats were fed either a control, 1.3 g/d, 2.6 g/d or 3.9 g/d. The rumen protected CLA 35 contained 17.5% of each of the cis 9-trans 11 and trans 10-cis 12 isomers respectively. Supplementation of up to 3.9 g rumen protected CLA 35, which is on a bodyweight basis, equivalent to 150% of the recommended level for cows, did not affect milk yield or composition. In a second trial 10 additional goats were used in a two treatment factorial design and fed either 30 or 60 g of rumen protected CLA 35. Milk lactose, protein and milk urea nitrogen concentrations were not affected. When the average milk fat percentage of the two days prior to the trial was compared with the fat percentage on day 8, 60 g rumen protected CLA 35 reduced milk fat by 0.57 percentage units compared to 0.07 units when 30 g rumen protected CLA 35 was fed. The results suggest that much higher levels of rumen protected CLA/unit of body weight would be needed in goats, as compared to cows, to suppress butterfat production to the same extent as in cows. Therefore, dairy goats cannot merely be used as a model for cows in butterfat depression studies and more long-term studies on CLA supplementation of goats are needed.

Palabras clave : Conjugated linoleic acid; Saanen goats; milk composition; milk yield.

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