- Email: [email protected]
Mild Production of Young Cows Compared With That of Mature Cows
M I L D P R O D U C T I O N OF YOUNG COWS C O M P A R E D W I T H T H A T OF M A T U R E COWS J. J. H O O P E R
Department of Anima~ Husbandry, University of Kengucky, Lexington, Kenguv2ay
The question is often asked as to how much more milk will a mature cow yield than a two-year-old cow with her first calf. I n other words, if a heifer produces6700 pounds of milk and 360 pounds of butter fat during her first year's milking,-how much will she yield a s a mature cow, and at what age will she mature, or at what age will she produce the largest quantity? To determine this matter I studied the yearly official test records o f 865 Jersey cows, so my work relates only to tl~at breed, although it holds good in a general way for all dairy breeds. The records are as follows: Production of young cows compared with that of mature cows A G E OF COW
NUMBER OF COW8
PER CENT
pOUndS
year
1 2 3 4 5 6 7 8 9 10
MILK
86 278 126 112 91 60 47 29 25 11
68 74 82 91 91 94 100 97 97 98
6, 267 6, 707 7, 496 8, 231 8, 222 8, 490 9, 029 8, 755
8,718 8, 887
B UTI~ER F A T
pounds 337 359 399 449 441 46O 477 462 476 464
P Z R CENT
71 73 81 94 92 96 100 97 I00 97
From the above table it is found that a heifer that produces 6700 pounds of milk and 360 pounds butter fat as a two-year-old will yield 9000 pounds milk, and 480 pounds butter fat as a mature cow, at seven years of age. But she becomes over 90 per cent as efficient at four years old, or practically mature with the third 451
452
J.J.
HOOPER
calf. And apparently the cow will hold her maximum efficiency through her tenth year. We find also from this table that young cows gain an easier entrance into the Register of Merit than old cows, and the same is true with all dairy breeds. To prove this statement we will call attention to the fact that six-year-old cows exceed two-year-old cows by 101 pounds fat, or by 23 per cent, while the standard for entrance into the official test book has a difference between these ages of 110 pounds (250 pounds for two year-olds and 360 for five years and over) or 30 per cent. To state it differently a two-yearold excels her requirement by 30 per cent, and the six-year-old one excels .hers by only 22 per cent. But the error is not a serious one.
Department of Anima~ Husbandry, University of Kengucky, Lexington, Kenguv2ay
The question is often asked as to how much more milk will a mature cow yield than a two-year-old cow with her first calf. I n other words, if a heifer produces6700 pounds of milk and 360 pounds of butter fat during her first year's milking,-how much will she yield a s a mature cow, and at what age will she mature, or at what age will she produce the largest quantity? To determine this matter I studied the yearly official test records o f 865 Jersey cows, so my work relates only to tl~at breed, although it holds good in a general way for all dairy breeds. The records are as follows: Production of young cows compared with that of mature cows A G E OF COW
NUMBER OF COW8
PER CENT
pOUndS
year
1 2 3 4 5 6 7 8 9 10
MILK
86 278 126 112 91 60 47 29 25 11
68 74 82 91 91 94 100 97 97 98
6, 267 6, 707 7, 496 8, 231 8, 222 8, 490 9, 029 8, 755
8,718 8, 887
B UTI~ER F A T
pounds 337 359 399 449 441 46O 477 462 476 464
P Z R CENT
71 73 81 94 92 96 100 97 I00 97
From the above table it is found that a heifer that produces 6700 pounds of milk and 360 pounds butter fat as a two-year-old will yield 9000 pounds milk, and 480 pounds butter fat as a mature cow, at seven years of age. But she becomes over 90 per cent as efficient at four years old, or practically mature with the third 451
452
J.J.
HOOPER
calf. And apparently the cow will hold her maximum efficiency through her tenth year. We find also from this table that young cows gain an easier entrance into the Register of Merit than old cows, and the same is true with all dairy breeds. To prove this statement we will call attention to the fact that six-year-old cows exceed two-year-old cows by 101 pounds fat, or by 23 per cent, while the standard for entrance into the official test book has a difference between these ages of 110 pounds (250 pounds for two year-olds and 360 for five years and over) or 30 per cent. To state it differently a two-yearold excels her requirement by 30 per cent, and the six-year-old one excels .hers by only 22 per cent. But the error is not a serious one.