“Cholesterogenic" dietary factors and milk and milk fat yields in dairy cows

Authors

• Pellervo Saarinen Department of Animal Husbandry, University of Helsinki

DOI: https://doi.org/10.23986/afsci.71470

Abstract

The following results have been obtained from a statistical investigation carried out on experimental results from 27 feeding trials in which the effect of cholesterogenic dietary factors, observed in an earlier investigation (5), on the relative levels of milk and milk fat yields are compared. An execessive intake of energy either has no statistically clear effect on the level of yield, or the effect is negative. In this respect the results obtained are uniform with experimental results obtained in Norway and Denmark using other methods (1, 6). In the negative cases the effect appears more clearly in the level of milk and milk fat yields than in the plasma cholesterol content. An excessive intake of protein shows a negative effect only in well-conditioned obese cows. An increase of the proportion of digestible crude fibre in the food ration appears in most cases to have an increasing effect on the milk yield. This effect, however, seems to be slighter than the effect on the blood plasma cholesterol content. The level of milk and milk fat yields has proved to be statistically in positive partial correlation to the digestible crude fat intake in g/kg live weight ,and in negative partial correlation to the relative fat intake compared with the nutritional requirements of the animal. This indicates that the favourable level of fat intake varies according to the level of milk yield, being larger in stages of higher yields than in stages of small yields.