Use of fat in fattening diets for cattle

Abstract

The incorporation of dietary fat is quite usual with fattening cattle. The objectives are an increase of the energy content of the diet, a better finishing period and the ability to manipulate the unsaturated fatty acids content of fat in the carcass. Fat is incorporated either as purified fat of vegetable or of animal origin or as an oil producing seed or bean. Usually, feedstuffs are treated with as result, for example, an increase of the content in saturated fatty acids with shorter chains. Since fat sources of various origins have been used in the different trials, opposite results were sometimes reported. The incorporation of fat in fattening diet tended to reduce the extent of fermentation in the rumen and direct the fermentation to a larger proportion of propionic acid. From the litterature it appeared also that fat reduced apparent digestibility of dry matter and organic matter and increased digestibility of ether extract. The main effects on animal performances were a reduction of the length of the fattening period, an improvement of live weigth gain, and a decrease of food intakes with as result an improvement of the feed conversion ratio. The authors reported usually an increase in the carcass weight and the killing-out proportion. Carcass were also fatter. The chemical composition of the carcass and of the muscle and the lean meat was not largely affected. The supplementation with fat of animal origin induced a decrease of variable extent in the unsaturated fatty acids content. By contrast, the incorporation of fat of vegetable origin was characterized by an increase of desaturated fatty acids.