The nutritive value of raw and pasteurized milk for calves

Abstract

1. An experiment on the feeding of calves is described, which lasted over 2 years, and which was carried out on a healthy Shorthorn herd free from tuberculosis and contagious abortion.2. Alternate animals as they were born were allocated, without any selection whatever, to one or other of two groups. One of these was fed on raw, the other on pasteurized milk. Every animal received its mother's colostrum for 3 days before being put on the milk diet.3. The milk used was taken from the mixed morning's milk of the whole herd. It was divided into two parts, one of which was given raw, the other of which was submitted to low-temperature pasteurization at 145° F. (628° C.) for 30 nun, and subsequently cooled. The animals were fed morning and evening on measured quantities that were in strict relationship to their body weight.4. In addition to the milk, hay was allowed ad lib. Observations showed that practically none was eaten during the first month, after which each animal consumed about 1 lb. a day, rising to 3 lb. by the eighth week.5. With the exception of two weaklings which died after 15 and 23 days respectively from causes apparently unconnected with the nature of their diet, all the animals—twenty-five in the raw and twenty-three in the pasteurized group—throve well, and showed no obvious signs of rickets or anaemia.6. The average increase in weight over the 8-week period for the animals in the raw group was 53·72 lb., and in the pasteurized group 53·86 lb., or 61·18 and 62·94 per cent respectively. This practical identity in weight increase is all the more surprising in view of the fact that the number of bull calves was very much less in the pasteurized than in the raw group.7. The highest individual gain among the bull calves—one of 80 lb.—and the highest individual gain among the heifer calves—one of 63 lb.—both occurred in animals fed on pasteurized milk.8. At no time throughout the experiment was any observer, lay or professional, able to distinguish between the two groups of animals.9. The diet given, though permitting of good skeletal development, was insufficient to fatten the animals. After they had been transferred, however, to a normal diet at the conclusion of their 8 weeks in the experiment, they soon put on weight and within 2 or 3 months were indistinguishable in size or condition from animals that had received a more generous diet from birth.10. There is nothing in these results to suggest that the nutritive value of pasteurized milk for calves is in any way inferior to that of raw milk.