engleski

Interactive fat supplementation changed the milk quality and plasma thyroid hormone concentration in Simmental cows

Ten healthy multiparous Simmental cows in mid-lactation, with average 4.34 % of milk fat and 3.61 % of milk protein, were appointed for five weeks simple change-over feeding trial. The cows were randomly assigned in two groups, one treatment per group. Treatment 1 (WSO-diet) consisted of 41% concentrate, 33% perennial ryegrass haylage, 26% corn silage in DM, and Treatment 2, (SO-diet) comprised of WSO diet supplemented with 200 g of non-protected sunflower oil per cow and day. Milk production and the majority of milk components did not change significantly regarding the treatment, apart the milk urea concentration that increased in Treatment 2. The milk fatty acid profile was modified with the significant decrease in lauric, miristic and palmitic acid (4.23 vs. 3.64 ; 12.52 vs. 10.85 ; 31.21 vs. 24.50), and the increase in stearic, vaccenic, linoleic and conjugated linoleic acid (CLA) (10.70 vs. 15.26 ; 0, 61 vs. 0.96 ; 2.55 vs. 3.61 ; 0.71 vs.1.57) content. No remarkable changes in eicosapentaenoic and docosahexaenoic acid milk content, as well as in the index of milk lipid peroxidation were identified. The concentration of total tetraiodothyronine (T4) in plasma increased in Treatment 2 whereas no changes in total triiodothyronine (T3) concentration were detected. The positive correlation between CLA and T4 was determined (r=0.38 ; p<0.05). We may suspect that supplementation of low content of interactive sunflower oil in the diet influenced the thyroid hormone secretion and partially modified the fatty acid profile of milk fat, with lowering effect on unfavorable lauric and palmitic acid, and raising the dietary source of bioactive CLA in raw milk.

cows; thyroide hormones; milk fatty acids; metabolism

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