Relations between the production of fatty acids in the rumen and their content in the milk fat of cows fed with different silages
2008
Petkova, M., Institute of Animal Science, Kostinbrod (Bulgaria) | Zhelev, K., Executive Agency for Reproduction and Selection in Animal Husbandry, Sofia (Bulgaria) | Petrova, N., Institute of Animal Science, Kostinbrod (Bulgaria) | Cheshmedzhieva, S., Institute of Animal Science, Kostinbrod (Bulgaria)
The aim of this study was to determine whether there is a correlation between the production of the volatile fatty acids in the rumen and the level of the fatty acids in the milk fat of cows as well as to assess the effects for the possibilities to influence the milk fat content trough the feeding. In the experiment with 2 x 6 cows in the beginning of their lactation from the 7th to the 60th day the feeding of the groups differed in the kind of the utilized ad libitum silage: from sorgum and sudan grass and from maze, for the experimental and control group respectively. During the 54-day experimental period three individual milk tests were made within equal time intervals for determination of the fatty acids in the milk fat and also rumen liquid samples were taken per os with a stomach tube for detection of the volatile fatty acids production. It was found that the utilization of the sorgum and sudan grass silage as 35% share of the ration dry matter with a ratio of roughages to concentrates 55:45 led to production of 44.78 mM/l total VFA in the rumen, and the dynamics of the fermentation changes was most intensive 2 h after feeding. The results obtained for the fatty acids content of the milk fat showed that the content of oleic acid was predominant 30.8% on average, followed by palmitic acid 26.17 % on average, irrespective of the kind of silage and the period for control. A positive relation was found between the total amount of volatile fatty acids in the milk and the ratio of С2/C 3 produced in the rumen r = 0.94; R2 = 88.00. When a maze silage was used, a significant positive relation was found between the sum of С2+C 3 and medium-length fatty acids in the milk r = 0.94; R2 = 87.63. A conclusion was drawn that in feeding lactating cows and through the processes in the rumen it is possible to influence the milk fat content. The determined correlations between VFA in the rumen and the FA in the milk fat showed the possibilities for such an influence.
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