168 MILK AND ITS HYGIENIC RELATIONS 



advantage in favour of the raw milk over the boiled milk of the 

 same species. 



The age of the calf is shown to be of great importance in dealing 

 with the nutritive value of the food. Thus a group of four calves 

 which received raw milk and chalk required 9*01 kilos, of milk 

 in order to put on I kilo, of body-weight in the first five weeks of 

 life, and required 14*99 kilos, of milk for the same increase in 

 body-weight on the second five weeks of life. 



If these two periods are taken together, then 12-08 kilos, of 

 milk are required for I kilo, increase of body- weight. 



Another set of six calves which were fed upon boiled milk and 

 chalk required 13*23 kilos, of milk during the first period of five 

 weeks and 13-25 kilos, for the second period, in order to add I kilo, 

 to their body-weight. 



The net results of both periods show a slight difference in 

 favour of the raw milk, but Hittcher justly points out how great 

 the error might have been in drawing deductions from either 

 period taken alone. 



The table given by Hittcher, which is reproduced above in full, 

 shows that the addition of salts is a more important factor than 

 the actual boiling of the milk. The kilos, of milk are calculated 

 from the values of total solids obtained by actual analysis, on the 

 basis of milk containing 11-5 per cent, of solids. 



The salt content of the milk is evidently of great importance. 

 If the addition of salts to mother's milk can bring about such 

 striking differences, then that difference in salt content, which is 

 known to exist between the milks of different species of animals, 

 may reasonably be expected to play an important part in the 

 nutritive value of the milk of a foreign species. 



Hittcher justly emphasises the importance of conducting experi- 

 ments over a long period of time, and of estimating daily the solid 

 value of the food taken, and not merely taking the weight of liquid 

 milk given. 



A single experiment was made on boiled goat's milk as a food 

 for kids by Bnining in 1906. This will be considered with the 

 experiments in Chap. X. 



Jt would appear that the salt content is of far greater 

 importance than any effect which can be produced by boiling. 

 Babick (1912) says that common salt should be added to the food 

 of milking cows. If this is not done, he finds that at varying periods 

 after commencement of lactation the cow shows signs of ill-health, 

 loss of appetite, rough coat, loss of weight, and decreased milk 

 supply. The more milk is given by the cow, the greater the effect 

 produced. Common salt speedily restores the cow to health. 



Dammann (1912) carried out an experiment with raw milk and 

 milk kept at 100 C. for an hour. Three calves were used ; (i) and 

 (2) received the heated milk and (3) raw milk. The experiment 

 extended over two months. During the first month only milk was 



