ANIMAL HUSBANDRY. Ill 



condition ma^^ be partly due to feeding, and arrangements have 

 been made for a large scale feeding experiment with sows to test 

 the effect of feeding upon size of litter, and to find out not only 

 how far feeding may be effectual in increasing the size of a litter, 

 but how far it is desirable to go in this direction ; in other words, 

 what is the best size of litter to be aimed at, and how, by feeding, 

 can this size be secured. The experiment will extend over three 

 years, during which it is hoped that 240 breeding sows will be 

 dealt with. 



The factors which influence the production of milk by the 

 cow are also being studied at the Aberdeen Institute, and already 

 certain facts have been discovered which, if confirmed by subse- 

 quent experiments, will throw valuable light on the subject of the 

 effect of feeding on milk production. In past work on this subject, 

 attention has been chiefly directed to the fat, " total solids," 

 and salts in milk. At Aberdeen an extensive investigaton has 

 been carried out in which the milk was analysed for fat, sugar, 

 salts, casein, albumin, and globulin and non-protein nitrogen. 

 It has been found that on a fixed diet, as the volume of milk 

 increases the percentage of sugar also increases, but the percentage 

 of protein and salts diminishes. The results suggest that one of 

 the factors that determine the daily volume of milk is the rate 

 of formation of sugar in the mammary gland. The fact that 

 independently of the nature of the diet the percentage composition 

 of milk tends to vary with the volume may explain many 

 apparently contradictory results obtained in investigations 

 carried out to determine the effect of feeding on the quality of 

 milk. 



While on the subject of milk, reference may be made to an 

 enquiry which has recently been concluded at Cambridge into 

 the presence of " supernumerary glands," or extra teats, in the 

 udders of dairy cows. A large number of dairy herds were 

 examined in Berkshire, Somersetshire and Devonshire, and it 

 was found that more than half of the animals had these extra 

 teats. It was further found that the glands associated with the 

 teats very often function, secreting milk, but this milk, instead 

 of being drawn off as in the case of the four principal 

 teats, is re-absorbed and the milk sugar is excreted with the 

 urine. Thus there appears to be a waste of milk in the case of 

 animals possessing extra teats. 



Growth in Cattle and Sheep. 



We may conclude this chapter by referring to investigations 

 which are in progfess at Cambridge into the question of the growth 



