Variation among individuals, breeds, parities and milk fatty acid profile and milk yield of ewes grazed on pasture

The experimental flock of 328 ewes belonging to three breeds (148 Tsigai, 124 Improved Valachian, and 56 Lacaune) with ewes' parity 1-8 was grazed on natural pasture and milk was sampled on the same day in the morning. Fatty acid (FA) milk fat content in particular the content of conjugated linoleic acid (CLA), oleic acid (OA) and 12:0-16:0 saturated FA (SFA) was examined with regard to variation among individual ewes, breed, parity and milk yield. Individual ewes showed the most significant effect on the FA milk fat profile. The CLA milk fat content varied in the wide range of 5-26 mg g−1 FA, thus 5-fold among individual ewes. Similarly, the values of Δ9-desaturase indexes varied within a triple range. The ewes' breed and parity had only little effect on some milk FA and atherogenicity index, however systematic trends were found. The ewes' milk yield varied within a 12-fold range, and that of Lacaune ewes was significantly higher (P < 0.05) compared with other two breeds. An inverse not quite significant relations (P ≈ 0.05) between the milk yield and the CLA milk fat content were found in Tsigai and Lacaune breeds, and significant for Improved Valachian (P < 0.001). With increasing milk yield we observed an increase in 6:0-14:0 SFA milk fat content (P < 0.001) and a decrease in the content of unsaturated FA (P < 0.001) and stearic acid (P < 0.01), nevertheless, variations in the content of OA and linoleic acid were insignificant. The average milk yield of ewes' flock was similar with 1-3 parities, and it decreased approximately by 60% with increasing parities up to 7. A higher OA content (P < 0.001) and a lower myristic acid content (P < 0.001) for primiparous ewes for flock as well as for all the three breeds was the most striking difference between primiparous and multiparous ewes. Upon eliminating the data for 25% ewes with lower CLA milk fat content and lower milk yield, the average CLA milk fat content and milk yield of ewes flock increased approximately by 8% and 5%, respectively.