Influence of an energy deficient diet on milk composition
2010
Morel, I. | Collomb, M., Forschungsanstalt Agroscope Liebefeld-Posieux ALP, Posieux (Switzerland) | van Dorland, A. | Bruckmaier, R.
An experiment was set up to study the effect of an energy deficit of approximately 15 MJ per day for two weeks on the composition of milk fat. Twenty-four cows at the beginning of full lactation, which were fed the same diet (hay, mixtures of silage of grass and corn, potatoes, concentrates of energy, protein and minerals) and kept under the same conditions after calving, were allotted to two groups. In group C (control), the cows were fed according to the recommendations, whereas in group D (deficit), the cows were slowly introduced to a diet resulting in an energy deficit of 15 MJ/day for two weeks. This phase was followed by a two weeks return to a normal diet. During the deficit phase, the live weight, BCS, milk production and protein levels decreased whereas the urea and fat content of milk increased. Compared to the values measured during the adaptation phase, the composition of the fat content of milk tended to have increased long (C18 and more) chain fatty-acids (FA), mainly C18: 1c9 (oleic acid) as well as the sum of omega-3 FA. There was a proportional decrease in saturated FA compared to mono- and poly-unsaturated FA. The majority of the effects noted during the deficit period were partially or entirely reversed after two weeks back to a recommended diet.
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