- Email: [email protected]
The Effect of Prepartum Milking and of Feeding of Vitamin A Supplemented Ration on the Leucocyte Count of Postpartum Milk Samples
THE
E F F E C T OF P R E P A R T U M M I L K I N G AND OF F E E D I N G V I T A M I N A S U P P L E M E N T E D R A T I O N ON T H E L E U C O C Y T E COUNT OF P O S T P A R T U M M I L K S A M P L E S
OF
E. O. ANDERSON A.'qD P A T R I C I A MACLEOD
Department of Animal Industries, Storrs Agricultural Experiment Statio7 b University of Connectictlt, Storrs
This paper reports the effects of p r e p a r t u m milking and the feeding of a vitamin A-supplemented ration on the leucocyte counts of postpartum milk samples. An analysis of the effects of these factors on the composition of postpartum milk will be published elsewhere. 1 5iETHODS
Films of milk samples of the first postpartum milkings of 32 mastitis-free (3) cows were stained and examined by the methods prescribed by the American Public Health Association (2). The cows were milked on a 12-hour schedule. Sixteen were subjected to p r e p a r t u m milking, beginning 3 days before the calculated parturition date. The actual period of p r e p a r t u m milking varied from 36 hours to 9 days. Of these cows, milked prepartum, five were fed the basal ration and 11 the same basal ration supplemented by vitamin A. The other 16 animals were not milked before parturition. F o u r of these were fed the basal ration and 12 the supplemented diet. The leucocyte counts, expressed in millions of cells per ml. were converted to logarithms for statistical analysis. The milk samples of the four differentlytreated groups of animals were compared in respect to both the mean leucocyte count and the change in the leucocyte count during the first six milkings postpartum. RESULTS
The average leucocyte counts of the four groups differed less from one another than the error of the difference. The average log-counts of the p r e p a r t u m basal and vitamin A groups were 5.76 and 5.84, respectively, and those for the two groups milked only postpartum were both 5.77. In actual counts these correspond to the geometric means shown in the last row of table 2, together with the average amount of milk produced, in pounds. The number of leucocytes decreased strikingly and very significantly during the six postpartum milkings when averaged over all four groups. This downward t r e n d was somewhat less marked in the prepartum-milked cows than in the others, although the difference in the trend could not be considered as statistically significant. The addition of vitamin A to the ration had no effect upon the trend. Keyes et al. (2) found that the number of leucocytes was the highest in the Received for publication April 29, 1949. 1 This study is being conducted by g . D. Eaton, Department of Animal Industries, University of Connecticut. 8O4
805
THE EFFECT OF PREPART1JM MILKING
TABLE 1 Average mille production and leucocyte counts of postpartum milkings, for the four groups of experi~nental cows P r e p a r t u m milked cowsa Postpartum milking
1st 2nd 3rd 4th 5th 6th Av. for group
Basal ration
Non-prepartum milked C0wsb
Vitamin A Ration
Basal ration
¥itamin A Ration
Leucocytes
Milk
Leucocytes
Milk
Leucocytes
Milk
Leucocytes
(No./ml.)
Ub.)
(lV-o./m~.)
(lb.)
(No./.~t.)
Ub.)
(Yo./~l.)
Ub.)
1,202,000 1,112,000 617,000 427,000 407,000 302~000 589,000
14.53 8.37 10.69 14.68 14.19 17.25 13.29
676,000 851,000 537,000 513,000 479,000 490,000 575,000
12.26 16.58 16.92 19.68 17.62 20.68 17.29
1,000,000 1,175,000 562,000 525,000 555,000 550,000 692,000
9.99 1,122,000 14.00 12.35 2,042,000 7.88 15.23 4 9 0 , 0 0 0 14.55 16.67 355,000 17.38 16.77 229,000 17.68 15.33 263,000 17.08 14.39 589,000 14.76
Milk
a 16 cows: 5 on basal ration (1 Ayrshire, 1 Guernsey, 2 Holsteins, 1 Jersey) ; 11 on vitamin A ration (4 Guernseys, 3 Holsteins~ 4 Jerseys). b 16 COWS: 4 on basal ration (2 Guernseys, 1 Holstein, 1 J e r s e y ) ; 12 on vitamin A ration (2 Ayrshires, 3 Guernseys, 4 Holsteins, 3 Jerseys).
first milkings and dropped to normal (the actual number was not given) within 4 days after parturition. CONCLUSION
The mean leucocyte count of milk samples of postpartum milkings of healthy cows is not affected by prepartum milking or by the feeding of a vitamin A-supplemented ration. ACKNOWLEDGMENT
Tile authors wish to express their appreciation to C. I. Bliss, Biometrician, Storrs Agricultural Experiment Station, for his help in the statistical analysis of the data, and to H. D. Eaton, Department of Animal Industries, University of Connecticut, for the milk production figures. REFERENCES (1) AMERICAN PUBLIC HEALTH ASSOCIATION. Standard Methods for the Examination of Dairy Products. 8th ed. New York, N . Y . 1941. (2) KEYES, E. A., REID~ J. J., BECHDEL, S. I., BORL.~-ND, A. A.~ BEAM, A. L., AND WILLIAMS~ P.S. Pre-Partum Milking (Abs.). J. Dairy Sci., 27: 638-639. 1944. (3) PLASTRIDGE, W. N., ANDERSON, E. O., WILLIAMS, L. F., AND HALE, H . H . Infectious Bovine Mastitis. 9. Information on the Control of Chronic Mastitis. Storrs (Conn.) Agr. Expt. Sta. Bull. 255. 1946.
E F F E C T OF P R E P A R T U M M I L K I N G AND OF F E E D I N G V I T A M I N A S U P P L E M E N T E D R A T I O N ON T H E L E U C O C Y T E COUNT OF P O S T P A R T U M M I L K S A M P L E S
OF
E. O. ANDERSON A.'qD P A T R I C I A MACLEOD
Department of Animal Industries, Storrs Agricultural Experiment Statio7 b University of Connectictlt, Storrs
This paper reports the effects of p r e p a r t u m milking and the feeding of a vitamin A-supplemented ration on the leucocyte counts of postpartum milk samples. An analysis of the effects of these factors on the composition of postpartum milk will be published elsewhere. 1 5iETHODS
Films of milk samples of the first postpartum milkings of 32 mastitis-free (3) cows were stained and examined by the methods prescribed by the American Public Health Association (2). The cows were milked on a 12-hour schedule. Sixteen were subjected to p r e p a r t u m milking, beginning 3 days before the calculated parturition date. The actual period of p r e p a r t u m milking varied from 36 hours to 9 days. Of these cows, milked prepartum, five were fed the basal ration and 11 the same basal ration supplemented by vitamin A. The other 16 animals were not milked before parturition. F o u r of these were fed the basal ration and 12 the supplemented diet. The leucocyte counts, expressed in millions of cells per ml. were converted to logarithms for statistical analysis. The milk samples of the four differentlytreated groups of animals were compared in respect to both the mean leucocyte count and the change in the leucocyte count during the first six milkings postpartum. RESULTS
The average leucocyte counts of the four groups differed less from one another than the error of the difference. The average log-counts of the p r e p a r t u m basal and vitamin A groups were 5.76 and 5.84, respectively, and those for the two groups milked only postpartum were both 5.77. In actual counts these correspond to the geometric means shown in the last row of table 2, together with the average amount of milk produced, in pounds. The number of leucocytes decreased strikingly and very significantly during the six postpartum milkings when averaged over all four groups. This downward t r e n d was somewhat less marked in the prepartum-milked cows than in the others, although the difference in the trend could not be considered as statistically significant. The addition of vitamin A to the ration had no effect upon the trend. Keyes et al. (2) found that the number of leucocytes was the highest in the Received for publication April 29, 1949. 1 This study is being conducted by g . D. Eaton, Department of Animal Industries, University of Connecticut. 8O4
805
THE EFFECT OF PREPART1JM MILKING
TABLE 1 Average mille production and leucocyte counts of postpartum milkings, for the four groups of experi~nental cows P r e p a r t u m milked cowsa Postpartum milking
1st 2nd 3rd 4th 5th 6th Av. for group
Basal ration
Non-prepartum milked C0wsb
Vitamin A Ration
Basal ration
¥itamin A Ration
Leucocytes
Milk
Leucocytes
Milk
Leucocytes
Milk
Leucocytes
(No./ml.)
Ub.)
(lV-o./m~.)
(lb.)
(No./.~t.)
Ub.)
(Yo./~l.)
Ub.)
1,202,000 1,112,000 617,000 427,000 407,000 302~000 589,000
14.53 8.37 10.69 14.68 14.19 17.25 13.29
676,000 851,000 537,000 513,000 479,000 490,000 575,000
12.26 16.58 16.92 19.68 17.62 20.68 17.29
1,000,000 1,175,000 562,000 525,000 555,000 550,000 692,000
9.99 1,122,000 14.00 12.35 2,042,000 7.88 15.23 4 9 0 , 0 0 0 14.55 16.67 355,000 17.38 16.77 229,000 17.68 15.33 263,000 17.08 14.39 589,000 14.76
Milk
a 16 cows: 5 on basal ration (1 Ayrshire, 1 Guernsey, 2 Holsteins, 1 Jersey) ; 11 on vitamin A ration (4 Guernseys, 3 Holsteins~ 4 Jerseys). b 16 COWS: 4 on basal ration (2 Guernseys, 1 Holstein, 1 J e r s e y ) ; 12 on vitamin A ration (2 Ayrshires, 3 Guernseys, 4 Holsteins, 3 Jerseys).
first milkings and dropped to normal (the actual number was not given) within 4 days after parturition. CONCLUSION
The mean leucocyte count of milk samples of postpartum milkings of healthy cows is not affected by prepartum milking or by the feeding of a vitamin A-supplemented ration. ACKNOWLEDGMENT
Tile authors wish to express their appreciation to C. I. Bliss, Biometrician, Storrs Agricultural Experiment Station, for his help in the statistical analysis of the data, and to H. D. Eaton, Department of Animal Industries, University of Connecticut, for the milk production figures. REFERENCES (1) AMERICAN PUBLIC HEALTH ASSOCIATION. Standard Methods for the Examination of Dairy Products. 8th ed. New York, N . Y . 1941. (2) KEYES, E. A., REID~ J. J., BECHDEL, S. I., BORL.~-ND, A. A.~ BEAM, A. L., AND WILLIAMS~ P.S. Pre-Partum Milking (Abs.). J. Dairy Sci., 27: 638-639. 1944. (3) PLASTRIDGE, W. N., ANDERSON, E. O., WILLIAMS, L. F., AND HALE, H . H . Infectious Bovine Mastitis. 9. Information on the Control of Chronic Mastitis. Storrs (Conn.) Agr. Expt. Sta. Bull. 255. 1946.