A study of the effect of feeding oils to dairy cows and of the value of the Latin square lay-out in animal experimentation

Abstract

1. A description is given of an adaptation of the Latin square lay-out to experiments with dairy cows. Experiments were conducted to test the effect of adding various fats and oils to the ration, and since effects were rapidly produced the Latin square technique proved very efficient, experimental errors being rather lower than those usually obtained in experiments with crops.2. Seventeen separate experiments, including, in all, twenty-one different cows (many of whom were used more than once), were conducted; fourteen of these were short-term experiments with unit periods of 5 days, two were medium-term with unit periods of 10 days and one long-term with 20 days.3. Palm oil, butter, lard and possibly cotton-seed oil were found to increase butterfat yield, chiefly by raising the butterfat percentage of the milk. Soya-bean, linseed and whale oils were without effect. Cod-liver oil definitely decreased butterfat percentage and butterfat yield.4. It appears that the beneficial oils are those containing a large proportion of the saturated fatty acids.5. Experiments with the same oil were not always consistent, and it appears that the effect may vary from cow to cow, and also with the same cow at different times.