EFFECT OF BREED AND MILKING METHOD ON SOMATIC CELL COUNT, STANDARD PLATE COUNT AND COMPOSITION OF GOAT MILK

摘要

This study was conducted on three commercial dairy goat farms (A, B, C), on which does were milked using pipeline milking machines, milking buckets and by hand, respectively. Six to eight mastitis-free milking does of Alpine and Nubian breeds were selected from each farm. Composite samples, made of equal volumes of evening and morning milk, were collected monthly throughout the lactation (March-October). Milk samples were analyzed for somatic cell count (SCC), standard plate count (SPC), and percentages of fat, protein, lactose and solids-non-fat (SNF). The overall means were 9.3 X 10(5) SCC ml(-1), 9.1 X 10(2) cfu ml(-1) SPC, 4.08% fat, 3.20% protein, 4.41% lactose and 8.28% SNF, respectively. There was no significant effect of breed or milking method on SCC. Overall monthly mean SCC increased as lactation advanced. During the entire lactation period, 51% of the milk samples contained above 1 million SCC ml(-1). However, only traces (under 5 cfu ml(-1)) of mastitis-related pathogens were found in these high SCC samples. Nubian does produced milk with higher SPC, percent fat, protein and SNF than Alpine does (P < 0.05). Milk by bucket milking had lower SPC than that by pipeline and hand milkings (P < 0.05), although all milk samples were below the limits of the Pasteurized Milk Ordinance for Grade A raw milk. Pooled data showed that SCC had a minor but positive correlation with SPC (r = 0.14, P < 0.05, n = 312).