J. Hammond and J. C. Hawk 143 



It will be seen that there are great variations in the effect on different 

 individuals, and observation pointed to the conclusion that it was the 

 goats in the worst states of nutrition that showed a diminution in the 

 milk yield as a result of injection. Two explanations of this appear to 

 be possible, either (1) in the goats in a high state of nutrition the loss 

 of sugar by way of the kidney was not sufficient materially to alter the 

 amount of sugar in the blood and so the amount available for the 

 mammary gland, as would occur in goats with very little stored 

 carbohydrate ; or (2) the milk yield was only affected when the proteins 

 were disorganized to yield sugar and that the store of carbohydrates 

 in the well nourished goats acted as a shield to delay this disintegration. 



In either case it is evident that interference with the sugar meta- 

 bolism affected not only the amount of milk sugar but also the amount 

 of milk and protein without affecting to any great extent the amount 

 of fat produced. 



Discussion. 



The results of the experiments obtained in Series (b) have been 

 collated by interpolation of days and the results averaged and plotted 

 in the form of a curve. The curves (Fig. 1) show very clearly the effect 

 of lowering the state of nutrition on the yield and fat content. 



These results have a direct interest in view of the frequency with 

 which dairymen are prosecuted for selling milk deficient in fat. The 

 defence is often put forward that the milk was poor in fat in consequence 

 of a dry season and the shortage of feed. The results of our experiments 

 show on the contrary that, under such conditions of a reduced state 

 of nutrition, the milk is very rich in fat. It will be seen above however 

 that if, after such a period of low feeding, an abundant supply of food 

 is given the yield is increased but the percentage of fat is below normal. 

 This conclusion is in agreement with that of Eckles^, who found that 

 provided a cow is underfed after calving the percentage of fat in the 

 milk is influenced to a considerable extent by the fatness of the cow 

 at calving. Surveying the feeding experiments on dairy cows from 

 this point of view one sees repeated examples of this principle demon- 

 strated. Wakerley^ found that, although the yield of milk was greate 

 as a result of feeding Golden Tankard mangolds to cows, the quaHty 

 of it was impaired, but the total amount of butter fat was the same 



^ Univ. of Missouri, Agric. Exp. Sta. Bui., 100. 

 2 Rpt. Midland Agric. and Dairy Coll., 1905-6. 



