Development of conjugated linoleic acid and c18:1 content during in vitro rumen fermentation of dried and green forage

Causes of welfare reduction in dairy sheep flocks are presented and their impact on ovine milk and cheese quality is discussed. Attention is focused on climatic extremes, poor housing and milking hygiene, and nutritional imbalance: mechanisms are outlined through which stress-induced reduction of immune function can result in poor milk composition, deteriorated renneting ability of milk and altered proteolysis in cheese during ripening. In particular, the impact is brought out of exposure to high ambient temperature on the nutritional properties of ewe milk, in terms of increased short-chain and saturated fatty acids, and decreased unsaturated to saturated fatty acid ratio. As well, the relationship is highlighted between ewe welfare and udder health. Especially under poor hygiene conditions the risk of mastitis markedly increases due to reduction of the natural defense mechanisms of the teat and mammary gland and increased number and pathogenicity of the micro-organisms in contact with the entrance of the teat canal. Evidence is provided that rise in milk somatic cell count, in response to bacteria penetration into the udder, can lead to decreased milk yield and altered composition of milk and cheese, due to extensive epithelium secretory cell damage.