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Live Weight and Milk-Energy Yield in the Wisconsin Dairy Cow Competition
LIVE W E I G H T AND MILK-ENERGY YIELD IN THE WISCONSIN DAIRY COW COMPETITION W. L. G A I N E S
Illinois Agricultural J~xperiment Station, Urbana, Illinois
The Wisconsin Dairy Cow Competition was conducted during the years 1909-1911 and the records were published in some detail by Woll (1). Brody and Cunningham (2) recently utilized ~Toll's data to show that gross efficiency is independent of live weight. The object of the present paper is to extend their observaton to show that, in these records, milk-energy yield per unit live weight is independent of live weight. As will be developed, these two relations permit the deduction that the digestible feed energy of working maintenance is proportional to live weight (rather than a fractional power of live weight). The utilization of live weight and milk-energy yield per unit live weight in a philosophy of dairy cattle breeding will be mentioned. LIVE WEIGHT AND GROSS EFFICIENCY
Gross efficiency is defined as the percentage ratio of milk-energy yield to digestible feed energy consumed. What is the relation of this ratio to live weight as shown by Woll's data ? Milk-energy yield is estimated from the reported milk and fat yields in terms of pounds of 4-per-cent milk (FCM) by the .4M + 15F formula. Feed consumption is reported by Woll in terms of feed units (FU), one FU being the equivalent of one pound of corn. Live weight in pounds (W) is given for 369 cows. FCM, F C M / F U and FC1Vi/W have been computed for each of the 369 cows. For present purposes we are not concerned with the absolute values of gross efficiency but only its relation to live weight, which is equally well shown by FCM/FU. The correlation surface for W and F C M / F U is shown graphically in Figure 1, and gives r = + .345 ___ .032. This result seems to contradict the statement that gross effÉciencyis independent of live weight. However, Woll allows 8 FU per day on pasture for each cow regardless of her live weight, although he states, " t h e number of units at which pasture should be rated will vary greatly according to its quality and the production and live weight of the cows and may range between 4 and 12 units per d a y . " Qualitatively, correction of this rather serious error in the estimate of feed consumption would reduce, algebraically, the above value of r; quantitatively, it is quite possible it might reduce r to zero. We may accept provisionally the conclusion of Brody and Cunningham that, in these records, gross efficiency is independent of live weight. Received f o r p u b l i c a t i o n J u l y 25, ]938. 49
50
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FIG. 1. R e l a t i o n b e t w e e n m i l k - e n e r g y yield in p o u n d s of 4-per-cent milk per feed u n i t c o n s u m e d ( F C M p F U ) a n d live w e i g h t in p o u n d s ( W ) . T h e regression, shown b y t h e s t r a i g h t line, is F C M / F U = 1.096 + .000465W. Gross efficiency (100 × milk calories/ digestible f e e d c a l o r i e s ) = 2 3 . 7 3 ( F C M / F U ) , c o m p u t e d as milk calories--340FCIvl a n d digestible f e e d calories = 1 4 3 3 F U . LIVE WEIGHT AND ~IILK-ENERGY YIELD PER UNIT LIVE WEIGHT
The correlation surface for W and F C M / W is shown graphically in Figure 2, and gives r = - . 0 2 3 ± .035. It is clear that live weight and milk•
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FZG. 2. R e l a t i o n between m i l k - e n e r g y y i e l d i n pounds o f 4-per-cent m i l k p e r p o u n d live w e i g h t ( F C ~ / W ) a n d live w e i g h t in p o u n d s ( W ) . T h e r e g r e s s i o n , shown by t h e s t r a i g h t line, is F C ~ I / W - - 1 0 . 5 3 1 - .000256W.
T]~IE R E L A T I O N
OF MILK
51
TO GRADE O F C H E E S E
energy yield per unit live weight fluctuate independently of each other. Or, milk-energy yield tends to be a multiple of live weight. LIVE W E I G H T
AND
WORKING
MAINTENANCE
We may split feed consumed, FU, into two parts : feed for lactation, FU' ; and feed for working maintenance, F U " ; such that FU = F U ' + FU". We may assume FU" is proportional to FC/VI, and hence proportional to W, in these records. If F C M / F U is constant so far as related to W (gross efficiency independent of live weight) and FCM is proportional to W, it follows that F U is proportional to W, and FU", the feed for working maintenance, must also be proportional to W. While it is recognized the reported feed consumption of individual cows is erroneous with respect to pasture, this would not warrant the deductions made except for the support of other findings (3, 4). DISCLTSSIOb~"
Under rules of the Competition entry was open to cows of any breed and records might start with the fifth or any later day after calving and continue not to exceed 365 days during the same lactation. Grade and registered cows of the Jersey, Guernsey, and Holstein breeds were entered. The latest stage of lactation of any entry was 637 days after calving (No. 322, days in milk= 314, F C ~ = 9999.9). The shortest time in milk was 269 days (No. 295). It is obvious that such variation in days in milk and stage of lactation must have an effect on both yield and gross efficiency. In Table 1 correlations are given for subgroups by days in milk and by breed of cow. It will be noted in Table 1 that while for all breeds together W and F C M / W are independent, the same is not strictly true within any one of the breeds. This difference is associated with the fact that F C M / W is lowest for the smallest breed, and highest for the largest breed, thus :
Breed
mean W Jersey
....................
Guernsey Holstein
Other records
365-day records
930
mean FC~/W 10.125
mean W
903
mean FCM/W 8.899
...............
997
10.514
974
9.534
..................
1272
11.346
1202
10.830
It is quite unexpected to find such a condition, and it may be that as a breed the Holsteins had more nearly optimum conditions for maximum production than did the Jerseys, with the Guernseys intermediate. However that may be, the results emphasize the necessity of taking size of cow into account in a breeding philosophy (cf. 5, 6).
52
w . L . GAINES TABLE
i
Coe~cients of correlation (r) between live weight (W) and mil~-energy yield per unit live weight ( F C M / W ) , and between live weight (W) and mil~-energy yield per feed unit (FCM/t~U) by length of record and by breed of cow Breed
Item
Jersey
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
Guernsey
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
Holstein
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
All B r e e d s
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
365-day records * -
-
-
Other records
.08 17
.22 + .31 59
. 4 7
-
. 5 9
.13 68
.23 + .20 67
-
.06 + .31 152
-
All records .27 + .25 76
-
-
.12 + .28 76
.22 + .12 144
.64 + .15 82 -
-
. 0 6
+ .32 217
-
.45 + .22 149
-
.02 + .35 369
-
R e c o r d s s t a r t i n g w i t h i n 30 d a y s a f t e r c a l v i n g a n d c o n t i n u i n g 365 d a y s in milk. A n i m p o r t a n t point, on t h e side, in t h e 365-day records of all breeds t o g e t h e r is the relat i o n o f a g e to yield. D e a l i n g with cows u n d e r 6 y e a r s of a g e (106 cows, a g e s 1.79 to 5.90 y e a r s ) to a p p r o x i m a t e l i n e a r r e g r e s s i o n of yield on age, t h e correlation b e t w e e n a g e a n d F C I ~ is, r = + .30, a n d F C M - 8998 + 762 × a g e ; b e t w e e n a g e a n d F C M / W , r = + .14 a n d 1 0 0 0 F C M / W = 9742 + 234 × age. M o s t of t h e a g e t r e n d is removed in F C M / W a n d u s e of i n i t i a l live w e i g h t f o r W would p r a c t i c a l l y remove t h e a g e t r e n d completely. T h a t is, F C M / W n e e d s no "age c o r r e c t i o n s . " DAIRY CATTLE BREEDING PHILOSOPHY
1. Breed for size of cow, that is, set up size as a first characteristic. We can breed cows of any size from say 700 pounds to 1500 pounds with some degree of certainty. Some dairymen need large cows, others need small cows. This need can be directly met. 2. Breed for composition of milk, that is, set up milk composition as a second characteristic. F a t percentage may be a satisfactory measure of composition. W.e can breed for milk of any f a t percentage f r o m say 3 to 6 with some degree of certainty. Some dairymen need cows giving milk of high fat percentage, others, low fat percentage. This need can be directly met. 3. Breed for hard-working cows, that is, set up degree of work in lactation as a third characteristic. Milk-energy yield per unit live weight may serve as a measure of degree of work. All dairymen need cows with high development in this regard. I t is the most important to have, and least certain to breed for, of the three characteristics. The point of view is that the inheritance of milk production in the dairy cow goes back to having an organism strong enough to do the work, accomplish the energy transformations, directly and indirectly connected with heavy long-time milk giving. Size of itself is thus a p r i m a r y consideration. Knowing the size of the organism, the next consideration is to measure its
THE RELATION OF MILK TO GRADE OF CHEESE
53
proclivity to milk secretion, to obtain quantitative data for genetic study of this phase. Obviously, absolute milk yield is n o t directly suitable. Milkenergy yield per unit live weight may be directly suitable. Appropriate units need to be chosen and appropriate environment provided. The above point of view attempts to distinguish between high yield associated with large size of cow and high yield at a given size of cow. If we breed larger cows and secure higher yields, it may be that we have progressed only in the first characteristic (size) and not at all in the most important third characteristic (degree of work, or proclivity to lactation). It is necessary to distinguish between these two phases of development in the dairy cow. SUlY[~ARY
Records of 369 cows (Jersey, Guernsey, Holstein--grade or registered) show that milk-energy yield per unit live weight is independent of live weight ( r = - . 0 2 3 ) . The same records show that gross efficiency (milk energy/feed energy) increases with live weight (r = + .345). Elimination of recognized systematic errors in the feed record may reduce the latter correlation to zero, making gross efficiency, in fact, independent of live weight. Then, a permissible deduction is that the feed of working maintenance is proportional to live weight. In study of the genetics of milk yield in dairy cows, distinction should be made as to size of the organism which may be measured by live weight, and proclivity to lactation which may be measured by milk-energy yield per unit live weight. REFERENCES (1) W0LL, F. W. Studies in Dairy Production. Res. Bul. 26. 1912.
Univ. of Wisconsin Agr. Exp. Sta.
(2) BRODY,SAS~UEL,AND CUNNINGtIAM,RICHARD. Growth and Development, X X X V I I I ,
(3) (4) (5) (6)
Further Studies on the Energetic Efficiency of Milk Production and the Influence of Live Weight Thereon. Univ. of Missouri, Agr. Exp. Sta. Res. Bul 238. 1936. GAINES, W. L. Nutrients for Lactation, Working Maintenance and Gain in Live Weight in American Dairy Cows. JouR. DAIaY SCl. 21: 585-592. 1938. GAINES, W . L . Feed Units for Lactation, Working Maintenance, and Gain in Live Weight in Danish Dairy Cows. J o v m DAIRY SCI. 21: 645-650. 1938. GAINES, W. L. Correction Factors and Germ Plasm in Dairy Cattle Breeding. Proc. 28th (1935) An. Meet. Am. Soc. An. Prod. 50-53. 1936. GAINES, W . L . Working Maintenance as a Function of Live Weight in Dairy Cows, and Its Bearing on an Energy-Size Index of Lactation. JOUR. DAIRY ScI. 20: 583-598. 1937.
Illinois Agricultural J~xperiment Station, Urbana, Illinois
The Wisconsin Dairy Cow Competition was conducted during the years 1909-1911 and the records were published in some detail by Woll (1). Brody and Cunningham (2) recently utilized ~Toll's data to show that gross efficiency is independent of live weight. The object of the present paper is to extend their observaton to show that, in these records, milk-energy yield per unit live weight is independent of live weight. As will be developed, these two relations permit the deduction that the digestible feed energy of working maintenance is proportional to live weight (rather than a fractional power of live weight). The utilization of live weight and milk-energy yield per unit live weight in a philosophy of dairy cattle breeding will be mentioned. LIVE WEIGHT AND GROSS EFFICIENCY
Gross efficiency is defined as the percentage ratio of milk-energy yield to digestible feed energy consumed. What is the relation of this ratio to live weight as shown by Woll's data ? Milk-energy yield is estimated from the reported milk and fat yields in terms of pounds of 4-per-cent milk (FCM) by the .4M + 15F formula. Feed consumption is reported by Woll in terms of feed units (FU), one FU being the equivalent of one pound of corn. Live weight in pounds (W) is given for 369 cows. FCM, F C M / F U and FC1Vi/W have been computed for each of the 369 cows. For present purposes we are not concerned with the absolute values of gross efficiency but only its relation to live weight, which is equally well shown by FCM/FU. The correlation surface for W and F C M / F U is shown graphically in Figure 1, and gives r = + .345 ___ .032. This result seems to contradict the statement that gross effÉciencyis independent of live weight. However, Woll allows 8 FU per day on pasture for each cow regardless of her live weight, although he states, " t h e number of units at which pasture should be rated will vary greatly according to its quality and the production and live weight of the cows and may range between 4 and 12 units per d a y . " Qualitatively, correction of this rather serious error in the estimate of feed consumption would reduce, algebraically, the above value of r; quantitatively, it is quite possible it might reduce r to zero. We may accept provisionally the conclusion of Brody and Cunningham that, in these records, gross efficiency is independent of live weight. Received f o r p u b l i c a t i o n J u l y 25, ]938. 49
50
W.L. i
i
i
i
GAINES
i
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•
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18oo
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FIG. 1. R e l a t i o n b e t w e e n m i l k - e n e r g y yield in p o u n d s of 4-per-cent milk per feed u n i t c o n s u m e d ( F C M p F U ) a n d live w e i g h t in p o u n d s ( W ) . T h e regression, shown b y t h e s t r a i g h t line, is F C M / F U = 1.096 + .000465W. Gross efficiency (100 × milk calories/ digestible f e e d c a l o r i e s ) = 2 3 . 7 3 ( F C M / F U ) , c o m p u t e d as milk calories--340FCIvl a n d digestible f e e d calories = 1 4 3 3 F U . LIVE WEIGHT AND ~IILK-ENERGY YIELD PER UNIT LIVE WEIGHT
The correlation surface for W and F C M / W is shown graphically in Figure 2, and gives r = - . 0 2 3 ± .035. It is clear that live weight and milk•
~
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u
•
u
i
i
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FZG. 2. R e l a t i o n between m i l k - e n e r g y y i e l d i n pounds o f 4-per-cent m i l k p e r p o u n d live w e i g h t ( F C ~ / W ) a n d live w e i g h t in p o u n d s ( W ) . T h e r e g r e s s i o n , shown by t h e s t r a i g h t line, is F C ~ I / W - - 1 0 . 5 3 1 - .000256W.
T]~IE R E L A T I O N
OF MILK
51
TO GRADE O F C H E E S E
energy yield per unit live weight fluctuate independently of each other. Or, milk-energy yield tends to be a multiple of live weight. LIVE W E I G H T
AND
WORKING
MAINTENANCE
We may split feed consumed, FU, into two parts : feed for lactation, FU' ; and feed for working maintenance, F U " ; such that FU = F U ' + FU". We may assume FU" is proportional to FC/VI, and hence proportional to W, in these records. If F C M / F U is constant so far as related to W (gross efficiency independent of live weight) and FCM is proportional to W, it follows that F U is proportional to W, and FU", the feed for working maintenance, must also be proportional to W. While it is recognized the reported feed consumption of individual cows is erroneous with respect to pasture, this would not warrant the deductions made except for the support of other findings (3, 4). DISCLTSSIOb~"
Under rules of the Competition entry was open to cows of any breed and records might start with the fifth or any later day after calving and continue not to exceed 365 days during the same lactation. Grade and registered cows of the Jersey, Guernsey, and Holstein breeds were entered. The latest stage of lactation of any entry was 637 days after calving (No. 322, days in milk= 314, F C ~ = 9999.9). The shortest time in milk was 269 days (No. 295). It is obvious that such variation in days in milk and stage of lactation must have an effect on both yield and gross efficiency. In Table 1 correlations are given for subgroups by days in milk and by breed of cow. It will be noted in Table 1 that while for all breeds together W and F C M / W are independent, the same is not strictly true within any one of the breeds. This difference is associated with the fact that F C M / W is lowest for the smallest breed, and highest for the largest breed, thus :
Breed
mean W Jersey
....................
Guernsey Holstein
Other records
365-day records
930
mean FC~/W 10.125
mean W
903
mean FCM/W 8.899
...............
997
10.514
974
9.534
..................
1272
11.346
1202
10.830
It is quite unexpected to find such a condition, and it may be that as a breed the Holsteins had more nearly optimum conditions for maximum production than did the Jerseys, with the Guernseys intermediate. However that may be, the results emphasize the necessity of taking size of cow into account in a breeding philosophy (cf. 5, 6).
52
w . L . GAINES TABLE
i
Coe~cients of correlation (r) between live weight (W) and mil~-energy yield per unit live weight ( F C M / W ) , and between live weight (W) and mil~-energy yield per feed unit (FCM/t~U) by length of record and by breed of cow Breed
Item
Jersey
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
Guernsey
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
Holstein
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
All B r e e d s
r, W a n d F C M / W r, W a n d F C M / F U n u m b e r of cows
365-day records * -
-
-
Other records
.08 17
.22 + .31 59
. 4 7
-
. 5 9
.13 68
.23 + .20 67
-
.06 + .31 152
-
All records .27 + .25 76
-
-
.12 + .28 76
.22 + .12 144
.64 + .15 82 -
-
. 0 6
+ .32 217
-
.45 + .22 149
-
.02 + .35 369
-
R e c o r d s s t a r t i n g w i t h i n 30 d a y s a f t e r c a l v i n g a n d c o n t i n u i n g 365 d a y s in milk. A n i m p o r t a n t point, on t h e side, in t h e 365-day records of all breeds t o g e t h e r is the relat i o n o f a g e to yield. D e a l i n g with cows u n d e r 6 y e a r s of a g e (106 cows, a g e s 1.79 to 5.90 y e a r s ) to a p p r o x i m a t e l i n e a r r e g r e s s i o n of yield on age, t h e correlation b e t w e e n a g e a n d F C I ~ is, r = + .30, a n d F C M - 8998 + 762 × a g e ; b e t w e e n a g e a n d F C M / W , r = + .14 a n d 1 0 0 0 F C M / W = 9742 + 234 × age. M o s t of t h e a g e t r e n d is removed in F C M / W a n d u s e of i n i t i a l live w e i g h t f o r W would p r a c t i c a l l y remove t h e a g e t r e n d completely. T h a t is, F C M / W n e e d s no "age c o r r e c t i o n s . " DAIRY CATTLE BREEDING PHILOSOPHY
1. Breed for size of cow, that is, set up size as a first characteristic. We can breed cows of any size from say 700 pounds to 1500 pounds with some degree of certainty. Some dairymen need large cows, others need small cows. This need can be directly met. 2. Breed for composition of milk, that is, set up milk composition as a second characteristic. F a t percentage may be a satisfactory measure of composition. W.e can breed for milk of any f a t percentage f r o m say 3 to 6 with some degree of certainty. Some dairymen need cows giving milk of high fat percentage, others, low fat percentage. This need can be directly met. 3. Breed for hard-working cows, that is, set up degree of work in lactation as a third characteristic. Milk-energy yield per unit live weight may serve as a measure of degree of work. All dairymen need cows with high development in this regard. I t is the most important to have, and least certain to breed for, of the three characteristics. The point of view is that the inheritance of milk production in the dairy cow goes back to having an organism strong enough to do the work, accomplish the energy transformations, directly and indirectly connected with heavy long-time milk giving. Size of itself is thus a p r i m a r y consideration. Knowing the size of the organism, the next consideration is to measure its
THE RELATION OF MILK TO GRADE OF CHEESE
53
proclivity to milk secretion, to obtain quantitative data for genetic study of this phase. Obviously, absolute milk yield is n o t directly suitable. Milkenergy yield per unit live weight may be directly suitable. Appropriate units need to be chosen and appropriate environment provided. The above point of view attempts to distinguish between high yield associated with large size of cow and high yield at a given size of cow. If we breed larger cows and secure higher yields, it may be that we have progressed only in the first characteristic (size) and not at all in the most important third characteristic (degree of work, or proclivity to lactation). It is necessary to distinguish between these two phases of development in the dairy cow. SUlY[~ARY
Records of 369 cows (Jersey, Guernsey, Holstein--grade or registered) show that milk-energy yield per unit live weight is independent of live weight ( r = - . 0 2 3 ) . The same records show that gross efficiency (milk energy/feed energy) increases with live weight (r = + .345). Elimination of recognized systematic errors in the feed record may reduce the latter correlation to zero, making gross efficiency, in fact, independent of live weight. Then, a permissible deduction is that the feed of working maintenance is proportional to live weight. In study of the genetics of milk yield in dairy cows, distinction should be made as to size of the organism which may be measured by live weight, and proclivity to lactation which may be measured by milk-energy yield per unit live weight. REFERENCES (1) W0LL, F. W. Studies in Dairy Production. Res. Bul. 26. 1912.
Univ. of Wisconsin Agr. Exp. Sta.
(2) BRODY,SAS~UEL,AND CUNNINGtIAM,RICHARD. Growth and Development, X X X V I I I ,
(3) (4) (5) (6)
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