430 



The author states that it is a matter of frequent observation that iu 

 the case of the same cow at two diffeiept milkings, that milking furnish- 

 ing the largest quantity of milk will in general be poorer in percentage 

 of solids and fat; and also that the mixed milk of a number of cows iu 

 the same stage of lactation and receiving the same food, becomes richer 

 in percentage of solids as the period of lactation advances. Reasoning 

 from these facts, a general rule has been assumed to exist, namely, that 

 individual cows or those breeds of cows remarkable for a large milk 

 yield, give milk which on the average is poorer in solids than the milk 

 of individual cows or breeds of cows of ordinary milk yiehl. He grants 

 that under certain conditions such may be the case; but believes that 

 the existence of such a general law or rule renuiins to be proved. With 

 reference to this point tlie cows under exi)eriment were arranged in 

 groups of four acconling to the averag** daily yield of milk per 5(K) 

 kg. of live weight, and the average composition of the milk is given. 

 The averages for each of these groups are given in the following state- 

 ment: 



Relation biiiceen yield and composition of milk. 



Group 1 

 Group 2 

 Group 3 

 Group 4 



Daily yield per 



5<k> kp. live 



wei(;lit. 



Compo!<ition of tbe milk. 



Milk. 



Kg. 

 24.18 



20. m 



10.70 

 17.30 



BntUr. 



Fat. 



0.89 

 O.W 

 0.76 

 0.64 



Ptr e^n t. 

 3.086 

 3.407 

 3.222 

 3.081 



.SoliiU- 

 not-fut. 



Per emt. 

 8. 523 



8.430 

 8.474 

 8.400 



Fat in 

 total 



Bolids. 



I Specltic 



'graxitv of 



milk. 



SuliiU. 



Percent. 

 11.609 

 11.K18 

 11.695 

 11.4{$7 



Per eri)t. 

 26. .'w^ 

 21*. 77 

 27.5.1 

 26.61 



Degre' ». 

 30.0 

 30.0 

 30.3 

 80.1 



•ContAlniDR 83.33 per cent of fat; calculated from the total amount of f«t in tbe milk. 



This table shows that in the case of the 16 cows under experiment, 

 the milk of gnmp 4, giving the smalle.st quantity, was in no respect 

 richer than tliat of the groups giving the largest quantity. The aver- 

 ages for groups 2, 3, and 4 show a steady decrease with the decrease 

 in yield in all constituents except in solids-not-fat. The conclusion 

 might be n>aclied that with the.se cows a de<rease in yield of milk was 

 accompanied l)y a decrease in itercentage of solids. He believes that 

 in cases in everyday practice, Mhere it is noticed that the milk of cows 

 giving a large quantity is thin and relatively i>oor, the explanation may 

 be often tbund in in.sunicient nourishment supplied in proportion to the 

 amount of work performed. 



An arrangement of the cows in groups of four, on the basis of the 

 average percentage of fat in the milk, brings out the fact that with an 

 increase in the percentage of fat in the milk all of the other ingredi- 

 ents of the milk also iucreased. In general then, as shown by the per- 

 centage of fat in solids, those cows which gave milk absolutely richer 

 in f\it, also gave milk relatively richer in fat. The individual ability 

 of the cows to secrete largOi' amiumts of solitl materials in the milk 



