Changes in fat component in milk of dairy cows during the postparturient period
2001
Theera Rukkwamsuk(Kasetsart University. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Faculty of Veterinary Medicine. Dept. of Medicine) | Wensing, Theo(Utrecht University, Utrecht (Netherlands). Faculty of Veterinary Medicine) | Geelen, Math J. H.(Utrecht University, Utrecht (Netherlands). Faculty of Veterinary Medicine)
Percentages of fat component and fatty acid composition in milk of 4 control cows were compared with those percentages in milk of 7 experimental cows. During the dry period, the control cows were fed at restricted energy intake whereas the experimental cows were overfed. Blood was collected at-1, 1, 2 and 3 weeks from parturition for determination of nonesterified fatty acids (NEFA), and milk was collected daily for 14 days after parturition for determination of fat component and fatty acid composition. Before parturition, blood concentrations of NEFA were similar in both groups. After parturition, the concentrations of NEFA in both groups increased, and experimental cows had higher concentrations of NEFA at 1, 2 and 3 weeks than did control cows. This result indicated that experimental cows entered a deeper negative energy balance than did control cows. Experimental cows had higher percentages of milk fat than did control cows during the first 2 weeks of lactation, which indicated that massive fatty acids in the blood passed through the milk. The major fatty acids present in the milk were myristic acid (C sub(14:0)), palmitic acid (C sub(15:0)), stearic acid (C sub(18:0)), and oleic acid (C sub(18:1)). The concentrations of palmitic, stearic, and oleic acids were higher for experimental cows than for control cows. These results corresponded with the increased concentrations of palmitic, steartic, and oleic acids in the blood. In conclusion cows that were overfed during the dry period mobilized more body reserved particularly fat from adipose tissue after parturition, and the mobilized fatty acids were secreted with the milk in proportion to their concentrations in the blood. It is therefore possible to use the milk fat percentage as a parameter of negative energy balance in early lactating cows.
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