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RELATIVE VALUE OF RAW AND HEATED MILK IN NUTRITION
1132
SPECIAL ARTICLES the results of "fresh" and kept" sterilised milk are included. The results with " sterilised " milk, both fresh" and "kept," have been discussedand hardly need Those with raw milk present BY ELFREIDA C. V. MATTICK, M.Sc., Ph.D. Bristol further comment. various interesting features. The does of the first, AND second, and third generations all produced litters at J. GOLDING, D.S.O., F.I.C. a first mating ; in the later generations one or more in each case failed to produce litters. These failures (From the National Institute for Research in Dairying, in production were not, however, increasingly the University, Reading) numerous in successive generations. In the seventh generation, one doe of four did not become pregnant, IN a previous paper on the relative value of raw but the remaining three produced nineteen pups and heated milk in nutrition, long-continued feeding (litters of four, seven, and eight). None of these were weaned, for the does failed to lactate. It is experiments with rats in which different types of this lactate the to which seems to be failure limiting milk were used was described. It was shown that in the first experiment while a fourth generation factor in this type of experiment, and it is noticeable this is throughout the experiment and receiving raw milk were weaned successfully, only that be due present to inadequacy of the diet or to some dead pups were born to the second generation on may "fresh" sterilised milk, and no second generation unknown factor which is found to affect does in many similar experiments. were weaned on " kept " sterilised milk. A comparison of the rate of growth and average In that paper we said : " It is proposed to keep at similar age of the members of successive weight some members of this fourth generation in an is shown in Figs. 1 and 2 and in Table II. generations the to number successive determine of endeavour From Table II. it is seen that at 120 days the generations which can be raised on this particular diet." We now give the history of these subsequent average weights of the first generations (litter brothers and sisters) on each type of milk are somegenerations. what similar ; the " kept " sterilised bucks and the " RESULTS OF THE INVESTIGATION fresh " sterilised does having respectively the highest The technique used and the source of the milk and lowest values. No second generation was weaned remained unchanged. All the results given here are on "kept" sterilised milk while the second on from a first and single mating only, in each genera- " fresh " sterilised were quite abnormally small and tion. Except in the early stages when suitable light (photograph given in earlier paper).’ The were considered, mating was entirely numbers in these groups are so small that the results weights " random" within the possibilities of cross-mating. might quite reasonably be regarded as insignificant Ifit had been possible to keep all the rats which were except for the fact that the original rats in each group weaned and to carry out successive matings it is were litter brothers and sisters selected from two possible that our efforts would have been more litters only. No further comparison between groups successful; on several occasions families were weaned can be made. A quite definite falling off in weight from later but not from a first mating. It must be ofanimals of the same age on raw milk is shown in remembered that the diet was at no time considered subsequent generations compared with the first to be ideal. and second, but again it is interesting to note that The number of pups born and weaned in successive this is not progressive, the average weight of the generations are shown in Table I. For the sake of fourth to the seventh generations of bucks being con-
RELATIVE VALUE OF RAW AND HEATED MILK IN NUTRITION
comparison
TABLE RESULTS OF MATING IN SUCCESSIVE
GENERATIONS
1133
siderably higher and of the does either identical or slightly better than those of the third generation. These results are clearly indicated in Figs. 1 and 2, which show the average growth curves for bucks and does respectively in each successive generation until the time of mating. The significance of these differences between the average weight of the animals in the different groups and in different generations of the same group was found by comparing each with twice its standard * When
error.*
standard
a
The a hsemocytometer was used. haemoglobin was estimated by the acid hsematin method using a Klett colorimeter. The blood of rats aged 110-117 days which had been kept on the
from the tails and
difference is greater than twice its
error, we may
regard
the measurements
as
evidence of a real distinction between the two quantities whose difference is in question. In groups where the numbers are less than ten, a correction established by " Student," but in the form adopted by Jeffreys3 was introduced. This makes the comparisons considerably more stringent than they would otherwise be. The results of the statistical calculations show that the average weights of bucks and does in the three groups receiving raw, fresh " sterilised, and " kept " sterilised milk were not significantly different in the first generation. Differences between the second generation does on raw and " fresh " sterilised milk, and the first "
TABLE
II.-Average Weight
in Successive Generations
Calculated for all animals at 120
days
FIG. 1-Rate of growth in successive
experiment.
generations.
First
All bucks.
milk and biscuit diet showed a statistically significant higher number of red blood-cells, and lower
haemoglobin content, indicating a tendency to anaemia which, however, disappeared with increasing age. On the other hand, the animals on stock diet showed lower values of statistical significance--of both red cells and haemoglobin as they became older. At 358-386 days there were no statistically significant differences in either red cells or haemoglobin in the blood of the experimental and stock rats examined. Bone analysis.-Analyses of the leg bones of six rats of the second generation were carried out. These were one buck and two does from the raw and two bucks and one doe from the sterilised milk group. The age of all the rats was between 473 and 486 days. Statistical calculation of the results showed that the ash and calcium contents of the
*
generation weaned,t No second generation of these two does died at 126 days. A.w. c?$== average weight in grammes of bucks and does No
weaned ;
third one
respectively.
and second generation bucks and does on "fresh" sterilised milk are very significant. There is no significant difference between the average weights of successive generations from the third to the seventh in either bucks or does on raw milk. The reason for the falling off in weight in the third generation and subsequent stabilising is not known, but recorded data show that it is not apparently due to inbreeding, age of rats, or time of year at mating. It may be significant that the second generation rats were bred from does whose parents had been raised on a stock diet, and it is possible that the benefits of this original stock diet were not lost until after the second generation, while from the third onward the rats had become accustomed to this insufficient diet of biscuit and milk. Failures in lactation were found in the first generation. Red cells and hcemoglobin blood content.-Towards the end of this experiment some estimations of the number of red cells and haemoglobin content of the blood of stock (11 bucks) and experimental (5 bucks, 5 does) rats were made. The samples were taken * The standard error of the difference between two quantities is the square root of the sum of the squares of individual standard errors of the two quantities.
FIG. 2.-Rate
of
growth in successive generations. experiment. All does.
First
mills: fed rats were slightly but in those receiving sterilised than definitely greater milk. The differences in the phosphorus content bones of the
were
not
raw
significant.
Results of the analyses of the leg bones of a seventh generation doe (aged 516 days) showed that after four years’ feeding of successive generations on a diet of raw milk and flour and water biscuit there was no diminution in the ash, calcium, and phosphorus content of the bones. Condition of teeth.-It is interesting to note that at an age of 477 and 516 days respectively, no dental lesions could be found in a seventh generation buck
1134 world to report advances and progress in medical knowledge. It was, he said, one of the aims of the Ministry of Health to secure unity and cooperation in health and medical administration, to prevent overlapping and waste of effort, and so to secure the exertion of maximum effect. Between 1846 CONCLUSIONS and 1902 many other medical societies were formed (1) Rats from the same litters placed at weaning for the advancement of special studies, all doing excellent work within their own spheres. Owing to on diets of biscuit made from flour and water only and of (a) raw, (b) freshly sterilised, and (c) kept rivalry and lack of coordination, however, progress sterilised milk, show marked differences during a was not as marked as it should have been and it was a happy thing when the amalgamation of sevenlong-continued experiment. (2) No second generation was weaned from the teen of these societies ensured the success of what group receiving " kept " sterilised milk. No third became the Royal Society of Medicine. He congeneration was weaned from the group receiving gratulated the society on its financial stability and fresh " sterilised milk. Second, third, fourth, fifth, increasing membership, due in large measure to the sixth, and seventh generations were weaned from loyal service of the late Sir John MacAlister and of first matings only of successive generations in the Mr. Geoffrey Edwards. The Ministry of Health was raw milk group. primarily concerned with the prevention of disease these and it was becoming more difficult to draw the line the rats on (3) Although originally placed diets at weaning from stock (called first generation) where prevention ended and treatment began. This showed no significant differences in average weight society provided the Minister with standards on which to model and keep bright his work. He coupled at time of mating, the second generation does on fresh sterilised milk were significantly lower in weight with the toast the name of Dr. Robert Hutchison, than the original rats receiving either raw or sterilised equally distinguished as physician, medical historian, milk. wit, and expert on nutrition. (4) After the third generation no significant Dr. ROBERT HUTCHISON, in reply, spoke of the loss differences in the average weights of either bucks sustained by the society in the death of their patron, or does were found in successive generations on raw King George V. They hoped that Royal patronage milk. would again be extended to them by King Edward. (5) The possibility of ansemia in the younger rats In thanking the Minister of Health for his presence on the experimental diet is shown by a consideration he spoke of the pleasure felt by the society of putting of the statistical significance of the differences in before the Ministry the knowledge and experience of the average red cell count and hsemoglobin content the many great men contained in its ranks, for the of such rats compared with those on a stock diet of society knew no politics, medical or other. Their similar age-such differences are no longer significant only regret was that they were not consulted oftener. in the case of older rats. The society, he went on, had three functions to (6) Analysis of bones of rats of the second genera- perform : it had to supply the apparatus of knowtion on raw and fresh sterilised milk show that the ledge ; to provide for the interchange and diffusion bones of the former contain slightly more ash and of knowledge; and to promote good fellowship calcium than those in the latter group. amongst its members and the profession at large. (7) No dental lesions could be found in a buck and It was his belief that these three functions were only doubtful signs in the teeth of one doe of the efficiently fulfilled. The library, he was told, ranked seventh generation on raw milk. fourth among the great medical libraries of the world ; its maintenance was regarded as a first charge on REFERENCES income. Men in the remoter parts of the Empire 1. Mattick and Golding: THE LANCET, 1931, i., 662. had said how helpful the library service was to them. 2. Student " : Biometrika, 1908, vi., 1. 3. Jeffreys, S. H.: Proc. Roy. Soc. A., 1932, cxxxvili., 48 The sectional meetings were well attended, but he felt himself that the discussions were too polite; a little unparliamentary language at times would be a useful tonic. A tavern was, he thought, a good place ROYAL SOCIETY OF MEDICINE to be born in, for it at least ensured that the society was imbued with the spirit of sociability. There was THE biennial dinner of the society was held on no reason for a learned society to be solemn or May 9th, at the May Fair Hotel, London, when about pompous in its lighter moments and under the inspiration of the present secretary the society’s house was 180 fellows and guests sat down. The president, Dr. Robert Hutchison, was in the chair, and after the becoming more of a club and their receptions more loyal toasts " The Royal Society of Medicine " was frivolous-e.g., a recent study of the embryology proposed by the Minister of Health, Sir KINGSLEY of Mickey Mouse. Financially they were doing well ; WOOD, who remarked that he was to enjoy a night the budget had been balanced with a substantial out as the society had, he understood, nothing to surplus. They had done that off their own bats, do with medical politics. It was born, he was told, they had robbed no hen-roosts. He felt it a great in a tavern in 1805 under the name of the Medical honour to be president of the society, and a great and Chirurgical Society for the purpose of conversa- responsibility, although fortunately that responsition on professional subjects, for the reception of bility was shared, and he would be wanting in graticommunications, and for the formation of a library. tude if he did not acknowledge the constant help Since that time its numbers had increased until received from the honorary officers and from the to-day it was housed in a magnificent building in permanent staff. The toast of " The Guests " was proposed by Mr. Wimpole-street with a Royal Charter, a roll of over 5000 fellows, and twenty-four sections dealing with ERIC PEARCE GOULD, who paid a very pretty compliall branches of medicine. The printed " Proceedings " ment to their role at a medical dinner in pandering acted as the ambassador of the society all over the to doctors’ natural delight in gluttony. When we and only doubtful earliest signs of carious lesions in a doe of the seventh generation on raw milk. Examination of the teeth of these rats was very kindly made for us by Dr. Evelyn Sprawson of the London Hospital dental school.
"
"
SPECIAL ARTICLES the results of "fresh" and kept" sterilised milk are included. The results with " sterilised " milk, both fresh" and "kept," have been discussedand hardly need Those with raw milk present BY ELFREIDA C. V. MATTICK, M.Sc., Ph.D. Bristol further comment. various interesting features. The does of the first, AND second, and third generations all produced litters at J. GOLDING, D.S.O., F.I.C. a first mating ; in the later generations one or more in each case failed to produce litters. These failures (From the National Institute for Research in Dairying, in production were not, however, increasingly the University, Reading) numerous in successive generations. In the seventh generation, one doe of four did not become pregnant, IN a previous paper on the relative value of raw but the remaining three produced nineteen pups and heated milk in nutrition, long-continued feeding (litters of four, seven, and eight). None of these were weaned, for the does failed to lactate. It is experiments with rats in which different types of this lactate the to which seems to be failure limiting milk were used was described. It was shown that in the first experiment while a fourth generation factor in this type of experiment, and it is noticeable this is throughout the experiment and receiving raw milk were weaned successfully, only that be due present to inadequacy of the diet or to some dead pups were born to the second generation on may "fresh" sterilised milk, and no second generation unknown factor which is found to affect does in many similar experiments. were weaned on " kept " sterilised milk. A comparison of the rate of growth and average In that paper we said : " It is proposed to keep at similar age of the members of successive weight some members of this fourth generation in an is shown in Figs. 1 and 2 and in Table II. generations the to number successive determine of endeavour From Table II. it is seen that at 120 days the generations which can be raised on this particular diet." We now give the history of these subsequent average weights of the first generations (litter brothers and sisters) on each type of milk are somegenerations. what similar ; the " kept " sterilised bucks and the " RESULTS OF THE INVESTIGATION fresh " sterilised does having respectively the highest The technique used and the source of the milk and lowest values. No second generation was weaned remained unchanged. All the results given here are on "kept" sterilised milk while the second on from a first and single mating only, in each genera- " fresh " sterilised were quite abnormally small and tion. Except in the early stages when suitable light (photograph given in earlier paper).’ The were considered, mating was entirely numbers in these groups are so small that the results weights " random" within the possibilities of cross-mating. might quite reasonably be regarded as insignificant Ifit had been possible to keep all the rats which were except for the fact that the original rats in each group weaned and to carry out successive matings it is were litter brothers and sisters selected from two possible that our efforts would have been more litters only. No further comparison between groups successful; on several occasions families were weaned can be made. A quite definite falling off in weight from later but not from a first mating. It must be ofanimals of the same age on raw milk is shown in remembered that the diet was at no time considered subsequent generations compared with the first to be ideal. and second, but again it is interesting to note that The number of pups born and weaned in successive this is not progressive, the average weight of the generations are shown in Table I. For the sake of fourth to the seventh generations of bucks being con-
RELATIVE VALUE OF RAW AND HEATED MILK IN NUTRITION
comparison
TABLE RESULTS OF MATING IN SUCCESSIVE
GENERATIONS
1133
siderably higher and of the does either identical or slightly better than those of the third generation. These results are clearly indicated in Figs. 1 and 2, which show the average growth curves for bucks and does respectively in each successive generation until the time of mating. The significance of these differences between the average weight of the animals in the different groups and in different generations of the same group was found by comparing each with twice its standard * When
error.*
standard
a
The a hsemocytometer was used. haemoglobin was estimated by the acid hsematin method using a Klett colorimeter. The blood of rats aged 110-117 days which had been kept on the
from the tails and
difference is greater than twice its
error, we may
regard
the measurements
as
evidence of a real distinction between the two quantities whose difference is in question. In groups where the numbers are less than ten, a correction established by " Student," but in the form adopted by Jeffreys3 was introduced. This makes the comparisons considerably more stringent than they would otherwise be. The results of the statistical calculations show that the average weights of bucks and does in the three groups receiving raw, fresh " sterilised, and " kept " sterilised milk were not significantly different in the first generation. Differences between the second generation does on raw and " fresh " sterilised milk, and the first "
TABLE
II.-Average Weight
in Successive Generations
Calculated for all animals at 120
days
FIG. 1-Rate of growth in successive
experiment.
generations.
First
All bucks.
milk and biscuit diet showed a statistically significant higher number of red blood-cells, and lower
haemoglobin content, indicating a tendency to anaemia which, however, disappeared with increasing age. On the other hand, the animals on stock diet showed lower values of statistical significance--of both red cells and haemoglobin as they became older. At 358-386 days there were no statistically significant differences in either red cells or haemoglobin in the blood of the experimental and stock rats examined. Bone analysis.-Analyses of the leg bones of six rats of the second generation were carried out. These were one buck and two does from the raw and two bucks and one doe from the sterilised milk group. The age of all the rats was between 473 and 486 days. Statistical calculation of the results showed that the ash and calcium contents of the
*
generation weaned,t No second generation of these two does died at 126 days. A.w. c?$== average weight in grammes of bucks and does No
weaned ;
third one
respectively.
and second generation bucks and does on "fresh" sterilised milk are very significant. There is no significant difference between the average weights of successive generations from the third to the seventh in either bucks or does on raw milk. The reason for the falling off in weight in the third generation and subsequent stabilising is not known, but recorded data show that it is not apparently due to inbreeding, age of rats, or time of year at mating. It may be significant that the second generation rats were bred from does whose parents had been raised on a stock diet, and it is possible that the benefits of this original stock diet were not lost until after the second generation, while from the third onward the rats had become accustomed to this insufficient diet of biscuit and milk. Failures in lactation were found in the first generation. Red cells and hcemoglobin blood content.-Towards the end of this experiment some estimations of the number of red cells and haemoglobin content of the blood of stock (11 bucks) and experimental (5 bucks, 5 does) rats were made. The samples were taken * The standard error of the difference between two quantities is the square root of the sum of the squares of individual standard errors of the two quantities.
FIG. 2.-Rate
of
growth in successive generations. experiment. All does.
First
mills: fed rats were slightly but in those receiving sterilised than definitely greater milk. The differences in the phosphorus content bones of the
were
not
raw
significant.
Results of the analyses of the leg bones of a seventh generation doe (aged 516 days) showed that after four years’ feeding of successive generations on a diet of raw milk and flour and water biscuit there was no diminution in the ash, calcium, and phosphorus content of the bones. Condition of teeth.-It is interesting to note that at an age of 477 and 516 days respectively, no dental lesions could be found in a seventh generation buck
1134 world to report advances and progress in medical knowledge. It was, he said, one of the aims of the Ministry of Health to secure unity and cooperation in health and medical administration, to prevent overlapping and waste of effort, and so to secure the exertion of maximum effect. Between 1846 CONCLUSIONS and 1902 many other medical societies were formed (1) Rats from the same litters placed at weaning for the advancement of special studies, all doing excellent work within their own spheres. Owing to on diets of biscuit made from flour and water only and of (a) raw, (b) freshly sterilised, and (c) kept rivalry and lack of coordination, however, progress sterilised milk, show marked differences during a was not as marked as it should have been and it was a happy thing when the amalgamation of sevenlong-continued experiment. (2) No second generation was weaned from the teen of these societies ensured the success of what group receiving " kept " sterilised milk. No third became the Royal Society of Medicine. He congeneration was weaned from the group receiving gratulated the society on its financial stability and fresh " sterilised milk. Second, third, fourth, fifth, increasing membership, due in large measure to the sixth, and seventh generations were weaned from loyal service of the late Sir John MacAlister and of first matings only of successive generations in the Mr. Geoffrey Edwards. The Ministry of Health was raw milk group. primarily concerned with the prevention of disease these and it was becoming more difficult to draw the line the rats on (3) Although originally placed diets at weaning from stock (called first generation) where prevention ended and treatment began. This showed no significant differences in average weight society provided the Minister with standards on which to model and keep bright his work. He coupled at time of mating, the second generation does on fresh sterilised milk were significantly lower in weight with the toast the name of Dr. Robert Hutchison, than the original rats receiving either raw or sterilised equally distinguished as physician, medical historian, milk. wit, and expert on nutrition. (4) After the third generation no significant Dr. ROBERT HUTCHISON, in reply, spoke of the loss differences in the average weights of either bucks sustained by the society in the death of their patron, or does were found in successive generations on raw King George V. They hoped that Royal patronage milk. would again be extended to them by King Edward. (5) The possibility of ansemia in the younger rats In thanking the Minister of Health for his presence on the experimental diet is shown by a consideration he spoke of the pleasure felt by the society of putting of the statistical significance of the differences in before the Ministry the knowledge and experience of the average red cell count and hsemoglobin content the many great men contained in its ranks, for the of such rats compared with those on a stock diet of society knew no politics, medical or other. Their similar age-such differences are no longer significant only regret was that they were not consulted oftener. in the case of older rats. The society, he went on, had three functions to (6) Analysis of bones of rats of the second genera- perform : it had to supply the apparatus of knowtion on raw and fresh sterilised milk show that the ledge ; to provide for the interchange and diffusion bones of the former contain slightly more ash and of knowledge; and to promote good fellowship calcium than those in the latter group. amongst its members and the profession at large. (7) No dental lesions could be found in a buck and It was his belief that these three functions were only doubtful signs in the teeth of one doe of the efficiently fulfilled. The library, he was told, ranked seventh generation on raw milk. fourth among the great medical libraries of the world ; its maintenance was regarded as a first charge on REFERENCES income. Men in the remoter parts of the Empire 1. Mattick and Golding: THE LANCET, 1931, i., 662. had said how helpful the library service was to them. 2. Student " : Biometrika, 1908, vi., 1. 3. Jeffreys, S. H.: Proc. Roy. Soc. A., 1932, cxxxvili., 48 The sectional meetings were well attended, but he felt himself that the discussions were too polite; a little unparliamentary language at times would be a useful tonic. A tavern was, he thought, a good place ROYAL SOCIETY OF MEDICINE to be born in, for it at least ensured that the society was imbued with the spirit of sociability. There was THE biennial dinner of the society was held on no reason for a learned society to be solemn or May 9th, at the May Fair Hotel, London, when about pompous in its lighter moments and under the inspiration of the present secretary the society’s house was 180 fellows and guests sat down. The president, Dr. Robert Hutchison, was in the chair, and after the becoming more of a club and their receptions more loyal toasts " The Royal Society of Medicine " was frivolous-e.g., a recent study of the embryology proposed by the Minister of Health, Sir KINGSLEY of Mickey Mouse. Financially they were doing well ; WOOD, who remarked that he was to enjoy a night the budget had been balanced with a substantial out as the society had, he understood, nothing to surplus. They had done that off their own bats, do with medical politics. It was born, he was told, they had robbed no hen-roosts. He felt it a great in a tavern in 1805 under the name of the Medical honour to be president of the society, and a great and Chirurgical Society for the purpose of conversa- responsibility, although fortunately that responsition on professional subjects, for the reception of bility was shared, and he would be wanting in graticommunications, and for the formation of a library. tude if he did not acknowledge the constant help Since that time its numbers had increased until received from the honorary officers and from the to-day it was housed in a magnificent building in permanent staff. The toast of " The Guests " was proposed by Mr. Wimpole-street with a Royal Charter, a roll of over 5000 fellows, and twenty-four sections dealing with ERIC PEARCE GOULD, who paid a very pretty compliall branches of medicine. The printed " Proceedings " ment to their role at a medical dinner in pandering acted as the ambassador of the society all over the to doctors’ natural delight in gluttony. When we and only doubtful earliest signs of carious lesions in a doe of the seventh generation on raw milk. Examination of the teeth of these rats was very kindly made for us by Dr. Evelyn Sprawson of the London Hospital dental school.
"
"