Submitted to: American Dairy Science Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2000
Publication Date: N/A
Interpretive Summary: No Interpretive Summary.
The milk somatic cell count (MSCC) is the basis for abnormal milk control programs. The current legal MSCC limit for bulk tank milk for small ruminants in the United States is 106/ml. Milk somatic cell counts for goats are higher than MSCC for cows and sheep. Evaluation of 71 bulk tank samples from commercial goat herds indicated that 65% of the samples exceeded the legal limit. The MSCC for goats free from intramammary infection range from 200 to 2,000 x 103/ml. Cell counts for sheep are similar to cows and range from 10 to 200 x 103/ml. Milk secretion in goats and sheep is apocrine in nature and cytoplasmic particles, similar in size to milk somatic cells, are normal constituents in milk. Concentrations of cytoplasmic particles in sheep milk average 15 x 103/ml while goat milk averages 150 x 103/ml. Therefore, in order to obtain accurate MSCC, only cell counting procedures specific for DNA should be used. While intramammary infection contributes significantly to increased MSCC for goats and sheep, non-infectious factors such as parity, stage of lactation, season and milk yield have been related to increased goat MSCC. Cell counts for uninfected halves will average 200 x 103/ml during the first 3 months of lactation and progressively increase to > 1,000 x 103/ml during the latter months of lactation. For sheep, counts are highest during the first few weeks of lactation (500 x 103/ml) and decrease to 30 x 103/ml at the fifth week of lactation, which coincides with maximum milk production. Counts remain unchanged for the remainder of the lactation. A further clarification on use of MSCC in abnormal milk control programs for goat milk appears justified because of noninfectious factors that influence MSCC for goats.