Part-time grazing improves sheep milk production and its nutritional characteristics

The positive effect of part-time grazing with three different amounts of indoor-supplied concentrate on milk production and quality was studied in an experimental flock of latxa sheep in mid-lactation. The group that received the highest amount of concentrate (group 3) ingested the least amount of grass during the 4h the animals were on the pasture. Milk production increased by 30% (p⩽0.05) in the three groups that were allowed to graze as compared with the milk produced by the control group (group 0; always fed indoors). No change in the milk gross composition among the four experimental groups was observed. The milk from group 1 (which received the lowest amount of concentrate) had the highest concentration (p⩽0.05) of unsaturated fatty acids (FA), both total and polyunsaturated (PUFA), and the highest percent (56%) of non-atherogenic saturated FA (p⩽0.05) as compared to 49% in the control group. Consequently, the atherogenicity index of the milk from group 1 was the lowest (p⩽0.05) of all groups. In addition, the concentration of CLA isomer c9t11 in this milk was 50μg/g fat, but only 15μg/g fat in the control group and around 33μg/g fat in groups 2 and 3. Changes in milk triglyceride composition were also observed between control group and grazing animals. The Trolox equivalent antioxidant capacity (TEAC) value of milks from groups 1 and 2 was higher than those of milks from groups 0 or 3. Curd firmness to compression was lowest (p⩽0.05) in milk from group 1. These results clearly indicate that part-time grazing is a viable alternative to intensive indoor sheep milk production which allows the use of locally available resources and improves the nutritional quality of the milk.