Abstract

LEITNER, G. et al. Factors influencing milk quantity and quality in Assaf sheep and goat crossbreds. S. Afr. j. anim. sci. [online]. 2004, vol.34, n.5, pp.162-164. ISSN 2221-4062.

The present study aimed to analyze the major factors that influence milk yield in Assaf sheep and Saanen, and Shami x Anglo Nubian goats, the major small ruminant dairy breeds and crossbreds in Israel. Six different farms with 745 Israeli-Assaf dairy sheep and 682 goats were surveyed. Udder halves were tested for udder bacterial condition, California mastitis test (CMT), somatic cell count (SCC), N-acetyl-p-D-glucosaminidase (NAGase) activity and milk composition (fat, protein and lactose). Effects of subclinical mastitis caused by CNS include a drastic increase in SCC and a decrease in milk yield. Changes are more acute in sheep compared with goats: SCC was quadrupled and milk yield was decreased by 30% in sheep, and in goats SCC was doubled and milk yield was only slightly decreased. However, in both sheep and goats, the direct income loss from decreased milk yield and the strong immune response to bacterial udder contamination, which results in the increase of SCC, appear to be of much greater magnitude than noted in dairy cows. The implication of these results is that for a given percentage of animals with udders contaminated with CNS, the increase in SCC will be much higher in the bulk milk of dairy sheep than cows. In dairy sheep and goats, grading milk according to SCC as currently practiced in herd improvement programs will place great pressure on growers to produce milk of a higher quality.

Keywords : Sheep; goat; udder infection; milk yield.

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