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 4 h 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 50 μg/g fat, but only 15 μg/g fat in the control group and around 33 μg/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.