ON THE MILK OF THE COW. 335 



4. The addition of oil cake does not increase the quantity of butter, although it contained 



12 - 25 per cent of oil. This fact goes to show that oil is not employed in the animal 

 economy in the manufacture of butter ; neither will the milk become oily and taste of 

 oil, as has been supposed. 



5. There is a capacity for milk belonging to each cow, which, although the winter's milk may 



be increased by diet, yet the limits will be determined by the animal economy, and not 

 wholly by the quantity and quality of food. 



6. In feeding, the quantity of nutriment required being given, an increase of quantity beyond 



that amount is lost, or it is not assimilated, or will not be employed in making milk. 



7. The milk first obtained is poor in butter, the last rich : see analysis, p. 324. 



8. The casein increases by nitrogenous compounds, as oil cake, grains, &c, but there is no 



increase of butter by the use of oily compounds. 



The first milk is poor, both in butter and casein, and comparatively rich in sugar, but is 

 more watery by over 6 per cent. The common opinion here is, therefore, correct, and is well 

 understood, as I am informed, by some of our milkmen, who, to make their butter, save the last 

 of the milking, and supply the first to their customers for their coffee. 



The effect of food upon the value of the solid excrements. 



When an animal is fed upon hay, whether it is a cow or a horse, more than half of the solid 

 excrement will consist of silica, and being a substance which is not taken into the system, or if 

 it is, only more sparingly than any of the elements which enter into the composition of food. 



Manure of the horse and cow fed exclusively upon hay, has the following composition : 



Horse. Cow. 



Silex, 67-00 63-00 



Phosphate, 8-50 21-40 



Lime 3-50 1-20 



Magnesia, 0-35 * 



Potash, 6-30 3-65 



Soda ". 5-25 3-28 



Sulphuric acid, .... , 4-40 6-2& 



Chlorine, 0-40 0-0R 



The value of manures depends on the food : though the silica for the cereals and grasses I 

 deem important, yet for turnips — the esculents, their silica is almost useless. 



Feeding with screenings increased the amount of solid matter in the excrements : from hay 

 ,-jt was 19 ; screenings, 23 ; oil cake, 25 ; and so there is an increase in the phosphates thus,. 



