1024 EXPERIMENT STATION RECORD, 



tatioiis (Amorican Holderness, Ayrshire, Devon, Guernsey, Holstein, Jersey, and 

 Shorthorn), and the Minnesota data upon 17 separate lactations and cows (Jersey, 

 Guernsey, Shorthorn and their grades, I'olled Angus, and Grade Holsteins)." 



The following deductious are taken from the author's summary: 



" Monthhj rnriations during the period of lactation. — The average spring cow rapidly 

 hetters the (|uality of her milk, heginniug about five months after calving; the sum- 

 mer cow starts in as early as the third month, while the fall cow maintains fairly 

 even quality throughout her lactation period, seldom improving it more than 0.5 per 

 cent in fat content. The percentage of solids-not-fat also is most uniform month by 

 month in the milk of the fall cow. The percentage of solids- not-fat in the milk of 

 spring cows seems to lessen somewhat in the summer time. 



"The average fall cow 'holds out' [in yield] as a rule better than the average 

 spring cow, and, in the records now under discussion, as a rule gave larger yields. 



" The gross yields [of butter] of spring and fall cows in the Vermont herd were the 

 same, but in the New York and Minnesota herds, the average fall cow outstripped 

 the average spring cow. 



"The Vermont fall cow held up the evenness of butter production better than the 

 spring cow. Little, if any, difference was seen in this respect in the other herds. 



"Extreme variations in qnulity during the period of lactation. — The greatest monthly 

 variation in the quality of the milk of 115 cows was 3.06 per cent fat, the least 0.33 

 per cent fat. The -widest diflerenco involved a change from 26.4 lbs. of milk to 14 

 lbs. of milk to a pound of butter. The average variation was 1.26 percent fat. The 

 average monthly variation of spring cows was 1.62 per cent fat; of fall cows, 1.08 

 per cent fat; of summer cows, 1.25 iier cent fat. . . . 



"Two-thirds of the Vermont and Minnesota herds gave thinnest milk during the 

 first 2 months, and two thirds of the New York during the first 4 months. Ninety 

 per cent of the Vermont and Minnesota cows gave their richest milk after the seventh 

 month. Sixtj' per cent of the New York cows gave their richest milk before the 

 eighth month. The arbitrary limitation of the New York records to a 10 months' 

 lactation may partially explain this. 



" Variations in qnality and quantity of milk from year to year. — BiitOof 43 cows changed 

 10 per cent in (juality in successive years. Such slight change as was ma<le was for 

 the better iu two-thirds of the cases. Quantity changes are too dependent upon 

 feeding, etc., to admit of deductions being drawn. 



"The quality of themilk of strippers. — The milk given duringthelast few weeks before 

 going dry is richer in fat and solids-not-fafc, and of a higher specific gravity than the 

 average of the milking ]>eriod, provided the cow has been in calf for 2 months or 

 more. This is not so surely true if the cow goes dry when farrow or when but 

 recently served. 



" When to test a cow for quality and </uantity of milk. — A large number of comparisons 

 show that the average quality of the milk of the entire year may be found with con- 

 siderable accuracy by testing 2 composite samjilcs, taken in either of two ways. 



(1) Spring cows. — First sample taken 6 weeks after calving, and second from 

 6| to 7 J months after calving. 



'•'Summer cows. — First sample taken 8 weeks, and second one from (> to 7 months, 

 after calving. 



" Fall cows. — First sample taken from S to 10 weeks, and second Irom 5A to 7 months, 

 after calving. 



" (2) By analyzing 2 composite samples taken 2 weeks apart, date of taking in case 

 of spring and fall cows to be 6 months after calving, and in case of summer cows to 

 he 3 to 5 months after calving. 



"Quite close approximations to truth may lie obtained by weighing the milk dur- 

 ing 4 days in the middle of each month and calculating the total yield by multiplica- 

 tion. In 43 per cent of the cases, calculation was within 2 jjcr cent of truth. Butter 



