nr. vel. j. ( 1979). 135,40
THE EFFECTS OF KETOSIS IN DAIRY COWS ON BODY WEIGHT, MILK YIELD AND MILK COMPOSITION By J. O. L. KI NG
University of Liverpool, Veterinary Field Station, Neston, South Wirral, L64 7TE
SUMMARY
Observations were made on 53 cows when suffering from ketosis and when normal about seven to 10 days later. During this period the average body weight, milk yield and percentage of so lids-not-fat in milk were significantly reduced and the milk fat, protein and combined lactose and mineral percentages were non-significantly lowered. INTRODUCTION
Ketosis, also known as acetonaemia, is a metabolic disease associated with failure to ellect complete combustion of carbo hydrate and volatile fatty acids in the food with a consequent accumulation of ketones in the blood, urine, milk and tissues. The disease has a world-wide distribution and occurs mainly in dairy cows. Uncomplicated ketosis in the dairy cow is characterized by poor appetite, a marked decrease in milk production and an abnormally rapid loss of body weight. It is difficult to estimate the economic losses caused by bovine ketosis because the disease is rarely fatal but observations suggest that it is responsible for heavy losses to the dairy industry, particularly through lowered milk production. A secondary and contributory effect on losses is the culling or disposal of cows which fail to respond to treatment or which lose condition to such an extent that they are rendered uneconomic for further production. Belschner (1967) records that the rapid loss of body weight is greater than would be expected from the decrease in appetite and agrees with Sampson (1956) that milk production may be reduced to half the normal amount secreted or still less if the cow refuses all food. Shaw (1955) in a comprehensive review of the disease as encountered in herds in the United States of America estimated that the loss of milk represented a loss of ten million dollars per annum to the dairy industry in that country. Blackburn, Castle & Strachan (1958) conducted a trial using 12 Ayrshin; cows in a herd in which ketosis had been a major problem for at least the two previous winters. Ten of the cows developed ketosis and it was calculated that, on average, there was a loss of 15% of the milk yield in the early part of the lactation when the animals were affected. No relationship was found between the ketone content of the milk and its fat and solids-not-fat (SNF) content.
EFFECTS OF KETOSIS IN DAIRY COWS
41
Few other attempts have been made to measure the extent of the decrease in milk production and loss of body weight or to assess the effect on milk composition. It was for this reason that the study described in this paper was undertaken.
MATERIALS AND METHODS
Observations were made on 34 Ayrshire and 19 Friesian cows on farms in the Wirral peninsula over a period of JO years. Thirty-nine were in their third or later lactations and the remaining 14 were second calvers. They all calved between September and December and were observed while housed and not grazing. All the Ayrshires and nine of the Friesians were housed in cowsheds, the remaining 10 Friesians being kept in covered yards. The cows were observed first at two consecutive milkings, morning and evening, when they were not eating all their concentrate ration and their milk gave "a positive reaction to the Rothera test. The cows were given therapeutic treatment and the second observations were made at corresponding milkings when there were no obvious signs of illness and the Rothera test was negative, usually between seven and JO days later. The evaluation of the liveweight of adult dairy cows is affected appreciably by alterations in intestinal contents, apart from changes in true body reserves. To reduce errors due to differences in the wmghts of the intestinal contents as far as possible individual cows were weighed at approximately the same times at the start of the illness and after recovery. As they were fed at the same time each day it was expected that their intestines would be filled fairly uniformly at each weighing. The milks were thoroughly mixed before being sampled. The fat contents were determined by the British Standard Specification No. 696 (1955 ) Gerber method, the SNF contents by the British Standard Specification No. 734 ( 1959 ) density method, and the protein percentages by the amido-black dye method. The lactose and mineral contents were calculated by subtracting the protein percentage from the SNF percentage for each animal. The figures for yield were totalled and for fat, SNF, protein, and lactose and mineral contents were averaged for consecutive morning and evening milkings. The significances of the findings were determined by application of the t test.
RESULTS
The results are summarized in Table 1. Body weight During the period of illness the average liveweights of the cows fell and the differences in the means were significant. The weight of food in the alimentary canal would have contributed to the difference because at the time of the first weighing the cows would not have been eating concentrate food, although they would have been consuming roughage, while at the second weighing the animals would have been eating a full ration .
42
BRITISH VETERINARY JO URNAL , 135, I TABLE I
AVERAG E BODY WEI G HTS AND MILK YIELDS AND PERCENTAGES OF FAT , SNF , PROTEIN , AND LACTOS E A N D M I NE RALS IN THE MILK OF 53 COWS SUFFERING FROM KETOSIS ( I) AND AFTE R RECOVERY ( N )
Body weight (kg) Milk yie ld (I ) Fat (%) SNF (%) Prote in (%) Lactose and minerals (%)
5 1256 8·13 4·09 8·36 3·26 5 10
N
J- N
58 1·88 10 ·96 4·24 8 ·64 3 ·35 5·29
-69· 32 - 283 - 0·15 - 0·28 - 009 - 0·19
SEM 30·9407'" 0·7773"':'* 0·2100 0·0598'' '''' 0·1042 0·0989
% reduction
11 ·9 1 25·82 3·54 3·24 2·69 3·59
· P < O·05.
**', P
THE EFFECTS OF KETOSIS IN DAIRY COWS ON BODY WEIGHT, MILK YIELD AND MILK COMPOSITION By J. O. L. KI NG
University of Liverpool, Veterinary Field Station, Neston, South Wirral, L64 7TE
SUMMARY
Observations were made on 53 cows when suffering from ketosis and when normal about seven to 10 days later. During this period the average body weight, milk yield and percentage of so lids-not-fat in milk were significantly reduced and the milk fat, protein and combined lactose and mineral percentages were non-significantly lowered. INTRODUCTION
Ketosis, also known as acetonaemia, is a metabolic disease associated with failure to ellect complete combustion of carbo hydrate and volatile fatty acids in the food with a consequent accumulation of ketones in the blood, urine, milk and tissues. The disease has a world-wide distribution and occurs mainly in dairy cows. Uncomplicated ketosis in the dairy cow is characterized by poor appetite, a marked decrease in milk production and an abnormally rapid loss of body weight. It is difficult to estimate the economic losses caused by bovine ketosis because the disease is rarely fatal but observations suggest that it is responsible for heavy losses to the dairy industry, particularly through lowered milk production. A secondary and contributory effect on losses is the culling or disposal of cows which fail to respond to treatment or which lose condition to such an extent that they are rendered uneconomic for further production. Belschner (1967) records that the rapid loss of body weight is greater than would be expected from the decrease in appetite and agrees with Sampson (1956) that milk production may be reduced to half the normal amount secreted or still less if the cow refuses all food. Shaw (1955) in a comprehensive review of the disease as encountered in herds in the United States of America estimated that the loss of milk represented a loss of ten million dollars per annum to the dairy industry in that country. Blackburn, Castle & Strachan (1958) conducted a trial using 12 Ayrshin; cows in a herd in which ketosis had been a major problem for at least the two previous winters. Ten of the cows developed ketosis and it was calculated that, on average, there was a loss of 15% of the milk yield in the early part of the lactation when the animals were affected. No relationship was found between the ketone content of the milk and its fat and solids-not-fat (SNF) content.
EFFECTS OF KETOSIS IN DAIRY COWS
41
Few other attempts have been made to measure the extent of the decrease in milk production and loss of body weight or to assess the effect on milk composition. It was for this reason that the study described in this paper was undertaken.
MATERIALS AND METHODS
Observations were made on 34 Ayrshire and 19 Friesian cows on farms in the Wirral peninsula over a period of JO years. Thirty-nine were in their third or later lactations and the remaining 14 were second calvers. They all calved between September and December and were observed while housed and not grazing. All the Ayrshires and nine of the Friesians were housed in cowsheds, the remaining 10 Friesians being kept in covered yards. The cows were observed first at two consecutive milkings, morning and evening, when they were not eating all their concentrate ration and their milk gave "a positive reaction to the Rothera test. The cows were given therapeutic treatment and the second observations were made at corresponding milkings when there were no obvious signs of illness and the Rothera test was negative, usually between seven and JO days later. The evaluation of the liveweight of adult dairy cows is affected appreciably by alterations in intestinal contents, apart from changes in true body reserves. To reduce errors due to differences in the wmghts of the intestinal contents as far as possible individual cows were weighed at approximately the same times at the start of the illness and after recovery. As they were fed at the same time each day it was expected that their intestines would be filled fairly uniformly at each weighing. The milks were thoroughly mixed before being sampled. The fat contents were determined by the British Standard Specification No. 696 (1955 ) Gerber method, the SNF contents by the British Standard Specification No. 734 ( 1959 ) density method, and the protein percentages by the amido-black dye method. The lactose and mineral contents were calculated by subtracting the protein percentage from the SNF percentage for each animal. The figures for yield were totalled and for fat, SNF, protein, and lactose and mineral contents were averaged for consecutive morning and evening milkings. The significances of the findings were determined by application of the t test.
RESULTS
The results are summarized in Table 1. Body weight During the period of illness the average liveweights of the cows fell and the differences in the means were significant. The weight of food in the alimentary canal would have contributed to the difference because at the time of the first weighing the cows would not have been eating concentrate food, although they would have been consuming roughage, while at the second weighing the animals would have been eating a full ration .
42
BRITISH VETERINARY JO URNAL , 135, I TABLE I
AVERAG E BODY WEI G HTS AND MILK YIELDS AND PERCENTAGES OF FAT , SNF , PROTEIN , AND LACTOS E A N D M I NE RALS IN THE MILK OF 53 COWS SUFFERING FROM KETOSIS ( I) AND AFTE R RECOVERY ( N )
Body weight (kg) Milk yie ld (I ) Fat (%) SNF (%) Prote in (%) Lactose and minerals (%)
5 1256 8·13 4·09 8·36 3·26 5 10
N
J- N
58 1·88 10 ·96 4·24 8 ·64 3 ·35 5·29
-69· 32 - 283 - 0·15 - 0·28 - 009 - 0·19
SEM 30·9407'" 0·7773"':'* 0·2100 0·0598'' '''' 0·1042 0·0989
% reduction
11 ·9 1 25·82 3·54 3·24 2·69 3·59
· P < O·05.
**', P
