NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
278 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
It will be observed that there is a remarkable correlation between the rate of
growth of an animal and the mineral and protein content of its mother's milk. Since
the minerals do not supply energy in any form, their function is entirely different
from that of carbohydrate, fat or proteins. From the above table it is clear that the
milk of a rapidly growing species contains a larger proportion of ash. This is of
course intelligible from the fact that more mineral matter is necessary in these cases
to build up the bone and the skeleton. A similar correlation is observed between
the chemical composition of the body and that of milk of the same species as has
been shown by Bunge. 4
THE EVALUATION OF THE MINERAL REQUIREMENT.
It has been stated already that only in the case of lime and phosphoric acid is
the amount of mineral requirement known. An idea of the requirement for these two
substances may be obtained from the following considerations. It is known that
each of these ingredients is present in the animal body to the extent of about 1% of
the body weight of pig and about 2% in the case of bullock. On this basis, for an
increase of 100 lbs. in the body weight, the CaO and P 2 O 5 requirement will be about
1 lb. each. Godden and his co-workers 5 have found in metabolic experiments with
pigs that only 50% of the intake of these minerals is retained under normal favour
able conditions, and hence 2 lbs. of these minerals will be necessary for a 100 lbs. in
crease of live weight. For a calf nearly double these amounts are necessary. Thus
a calf putting on 1½ lbs. weight per day must therefore absorb from the intestine and
retain approximately ½ oz. of lime per day and a pig about ¼ oz. Ten pounds of
cow's milk contain roughly ¼ oz. of lime and ⅓ oz. of phosphoric acid. A cow giving
30 lbs. of milk per day is therefore subjected to a drain of ¾ oz. of the former and 1
oz. of the latter. The hen laying an egg a day is perhaps the largest producer in pro
portion to body weight. An egg production of 200 per annum requires 1¼ lbs. of lime.
It appears from the work of Sherman and Hawley 6 that with ordinary rations
about three times the amount required for constructional purposes should be pro
vided. That means, in the case of a young calf, that the ration should contain
about 1½ oz. of lime per day and in the case of a young pig about ¾ oz. A milch
cow giving 30 lbs. per day should have about 2.5 oz. For animals grazing on good
pasture these amounts are available. Good pasture contains about 1% of lime in dry
matter, so that a cow consuming grass equivalent to 20 lbs. of hay would obtain
just over 2.5 oz. On poor pasture however the percentage of lime may be as low as
0.5, and on such grazing she would receive only half of the amount of calcium
needed for a 30 lbs. milk yield. On indoor rations, the likelihood of deficiency
would be even greater, as most concentrates are relatively poor in calcium. Thus
MINERAL METABOLISM OF FARM ANIMALS
279
for example it would take 2 cwts. of a mixture of oats, bran and maize to yield 3 oz.
of lime. The danger of calcium deficiency arises therefore either when grazing on
poor pasture or during indoor feeding on concentrates. 7
A good deal of attention has been paid to the requirements of lactating animals
where the need for both these minerals is high. Large numbers of experiments
have been reported by various investigators to keep an animal in positive
calcium balance or to keep the animals in equilibrium. Forbes and his
co-workers 8 were unable to obtain a positive calcium balance with cows during
the first half of lactation, despite an abundant supply of calcium, phosphorus
and other minerals. Hart and others 9 succeeded in obtaining a positive calcium
balance by feeding alfalfa hay. In later experiments they could only reduce, but
not make positive, the negative balances of milking cows by substituting alfalfa hay
for timothy hay. These latter results were attributed by them to a faulty curing
of the hay which destroyed the vitamin assisting calcium assimilation. Many other
authors record beneficial effects from feeding fresh green food. Hart, Steenbock and
Hoppert 10 found that with milking goats the administration of cod liver oil converted
a negative to positive calcium balance, but the oil was not well tolerated. In some
experiments at the Rowett Institute in the case of young hog pigs on a ration of
maize, middlings, oat meal and blood meal, cod liver oil raised the calcium retention
from a minus quantity to over 60% of the intake. Irradiation with artificially pro-
duced ultraviolet light produced a similar effect both in growing and in lactating
animals. Thus, for example in the case of young pigs, exposure to light from a carbon
are lamp for one hour daily raised the calcium retention from 0.46 gram to 2.1 gram.
In lactating goats the effect of light was to diminish the loss of calcium or to convert
a loss to a gain. 11
BALANCE BETWEEN MINERALS.
The question of mineral requirement is intimately connected with assimilation
and retention, and balance between different mineral constituents. It is becoming
evident now that the ingestion of one mineral may profoundly affect the retention
of another mineral. Thus Henderson 12 has found with pigs that when the ratio of
lime to phosphoric acid in a ration is 1:1, there is an adequate assimilation and
retention of both elements, but when the ratio is only 1 : 2.5, the balances are very
much lower and the animals fare better under ultraviolet treatment. It is of course
well known that a high variation in CaO : P O ratio in the diet causes either a low
calcium or low phosphorus type of rickets in rats which is indeed the basis of
Sherman and Pappenheimer's 13 rachitogenic diet. Phosphorus may be present in
abundance and may be absorbed from the intestine in sufficient amounts, but unless
280 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
a sufficient amount of calcium be present it cannot be used for bone construction,
and the greater part may be lost in the excreta. According to Ingle 14 an excess
of phosphorus may deplete the body of previously stored calcium.
The nature of the diet, in certain other respects, also affects the assimilation of
calcium. Thus, for instance, a higher proportion of calcium appears to be absorbed
from fresh pasture than from most other food-stuffs. In the case of hay the method
of curing is of some importance, assimilation being more difficult from hay that has
been left lying out for a long time than from hay secured from minimum exposure
to the elements. In the case of children, Blauberg 15 found the assimilation of
calcium from human milk, cow's milk and an artificial food was respectively 82, 61
and 33 per cent. Sherman and Hawley 16 found that calcium in vegetables could
not be assimilated as easily as the calcium in cow's milk. The ratios of other con-
stituents of the ration to calcium are also of some importance. According to Ingle 17
excess of magnesium may limit absorption. There is an optimum ratio of fat to
calcium. The ratio of acid to basic radicles has also an influence, assimilation being
more rapid when there is an excess of acid radicles. The influence of a proper CaO :
P 2 O 5 ratio has already been mentioned. With regard to the assimilation of other
minerais, it is probable that the amount of calcium in the diet affects assimilation of
iron. With an ample calcium intake, the body can satisfy its needs from a smaller
amount of iron than is the case when the intake of calcium is limited. 18
A certain amount of controversy has centred round Bunge's theory 19 for the
necessity of a correct balance of Na: K in the diet. He showed that an excessive
ingestion of potassium salt causes an elimination of sodium and chlorine. This is of
importance in practical feeding of farm animals, because a depletion of sodium and
chlorine would tend to react unfavorably on the animals. Lengthy experiments on
heifers carried out by Hart and his collaborators 20 have however shown the in-
completeness of Bunge's theory. They found in the case of different groups of
animals, fed on rations of different cereals, but all having free access to salt that
the amount of sodium chloride consumed bore no relation to the potassium content
of the ration, either when used alone or when supplemented by potassium salts.
But an interesting question has been raised with regard to the effect of an abnormal
ratio of Na : K on the retention of other elements such as calcium. Thus Seeman 21
first suggested and Zander 22 supported the idea that an excessive K : Na ratio
may be the cause of rickets. Aron 23 also considered it probable that such a ratio
interfered with the deposit of calcium and bone formation in cattle, while Zuntz 24
has recorded that fodder which cause rickets usually show an excessive proportion
of K to Na. In recent years Richards, Godden and Husband 25 have investigated
the effect, on the metabolism of the growing pig, of increasing the proportion of Na
MINERAL METABOLISM OF FARM ANIMALS
281
to K by addition of sodium salts to a cereal ration, and have found that the addi-
tion of sodium chloride or sodium citrate led to increased assimilation and retention
of nitorgen calcium and phosphorus. In a later paper 26 it was found that the
addition of potassium citrate to the diet decreased the retention of the
above constituents. With regard to lime retention, potassium citrate led to a
decrease while sodium citrate showed an increased retention and the authors conclude
that a high Na : K ratio may have a considerable influence on the calcium assimilation,
THE INTER-RELATION BETWEEN ORGANIC AND INORGANIC CONSTITUENTS OF THE
DIET.
The first point that arises in this connection is the rôle of organic constituents
on the retention of minerals and secondly the rôle of minerals in the phenomenon of
digestion and absorption of the energy producing substances. Thus Auchinache 27
in a recent series of elaborate experiments with sheep finds that there is some
unidentified substance in green pasture which is superior to cod liver oil in assisting
assimilation and retention of lime and phosphoric acid. Godden and others 28 find
that with pigs on a ration badly balanced with respect to CaO and P 2 O 5 , the addi-
tion of oils like cod liver oil, linseed oil and olive oil caused a rise in the calcium and
phosphorus balances.
The question of the rôle of minerals on the digestion and assimilation of the
organic constituents of the food has not been throughly studied, but the results
obtained by Förster 29 are significant. When minerals were previously extracted
from the food, he found that on this diet dogs died sooner than in complete starva-
tion. Signs of disturbance of the digestive organs appeared early. They were soon
accompanied by increased excitability and weakness of the neuromuscular system.
The central nervous system was also affected, as was shown by the occurrence of con-
vulsions and periods of drowsiness. A remarkable feature of the experiments
was the profound disturbance caused by relatively small losses of inorganic salts
from the system. The total mineral matter of the body at the beginning
of the feeding with the diet from which all salt had been extracted was
estimated at 1500 grams. During the experimental stage, the body lost phos-
phoric acid and sodium chloride in greatest amounts compared with other minerals,
but the actual amount of loss of these minerals was only 30 grams and 7 grams
respectively before death occurred as a result of mineral starvation. A well
nourished body could lose a far larger proportion of its total protein, fat or
carbohydrate without showing any marked disturbance of its functions. 30
Regarding the effect of minerals on intestinal absorption, recent experiments by
the writer 31 on the rôle of blood calcium on carbohydrate metabolism point to some
282 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, III.
interesting probabilities. Thus with rats it has been found that a deficiency of
calcium in blood causes a large decrease of sugar absorption from the small intes-
tine. The question may now be raised as to the possibility of minerals functioning
as a limiting factor in the carbohydrate utilisation by larger animals. Magee and
Reid 32 have recently found that the addition of 0.2% phosphate increased the
absorption of sugar by 50% in rats. These studies open out interesting fields of
research in the physiology of absorption,
THE RELATIVE IMPORTANCE OF VITAMINS IN THE FEEDING OF STOCK.
There has been a good deal of confusion regarding the necessity of supplying
vitamins to farm animals. Many results have been ascribed to unknown food
factors which could easily be explained on the basis of their mineral constituents. 33
Thus according to Orr 34 in feeding experiments with fowls, where yeast is used as a
source of vitamin B, some of the beneficial results obtained by giving yeast, can also
be observed by giving a solution of inorganic phosphate and glucose in an amount
equivalent to that obtainable from yeast. It is known that fowls have a high
requirement of phosphorus while yeast is also a good source of phosphorus. The
beneficial rsults of cod liver oil have been attributed to its vitamin content. It
appears that vitamin D may be necessary for stock feeding. Apart however from
its vitamin D content, the value of the oil may be due to its iodine content.
Compared with ordinary feeding stuffs, many of which contain very little iodine, cod
liver oil is rich in this substance and the results obtained by Smith 35 on pigs and
Marine and Kimball 36 have shown that the administration of minute quantities of
iodine may be followed by marked beneficial effects. With regard to the necessity
of other vitamins, Theiler and his co-workers 37 in their experiments on cattle, sheep,
goats and horses on rations deficient in vitamins, did not observe any symptoms
which could be ascribed to vitamin deficiency. In the case of sheep, the addition of
vitamin B to the ration led to no improvement in their condition. The lack of
dependance of growing cattle on their rations for vitamin B 1
38 and B 2 has been
recently explained by the finding 39 that these factors are synthesised by the bacteria
in the rumen of the species. In their experiments on pigs which are rapidly growing
animals and therefore are likely to suffer from vitamin deficiency, Orr and his
collaborators 40 could not produce any sign of malnutrition on ration deficient
in vitamin A or C. Similar results have been obtained by Golding and his
co-workers 41 with vitamins A and D who could not produce rickets in pigs
on vitamin deficient diet although growth was stimulated in pigs of low weights
on supplying pure milk and other substances. It is thus obvious that the require-
ments of the pig for these vitamins must be so low that there is no danger of
MINERAL METABOLISM OF FARM ANIMALS
283
deficiency on any ordinary ration. Crowther 42 and White and Roberts 43 have
confirmed this view by practical experiments. Poultry 44 and also a calf 45 do
not seem to suffer from a deficiency of vitamin C, and with regard to other vitamins
the addition of cod liver oil to an already balanced diet is said not to give any im-
provement in growth, egg-laying or hatchability of the eggs. 46 The evidence on
this point, however, is somewhat conflicting. Thus Foster 47 states that in an
experiment conducted with two groups of hens, to ascertain the relative dietetic
values of linseed oil and cod liver oil, it was observed that the linseed oil group
developed the habit of eating their own eggs and others did not. On changing over
the diets, within a week the group now on linseed oil began to eat their eggs and
the former egg-eaters (now on cod liver oil) dropped the habit. Foster thinks that
there is some connection between this depraved appetite (pica) and avitaminosis.
It is interesting to note that the existence of a similar depraved appetite is well
known to poultry-keepers in India. Hart and others 48 consider that the effect of
cod liver oil on an unbalanced ration is due to its vitamin content. Baby chicks
grow very well when cod liver oil is administered, or ultraviolet light is given. Since
eggs are rich in vitamin A, some source of this substance is needed in the ration.
There is good evidence to indicate that a close relationship exists between the diet
of cows and hens and the vitamin A content of milk and eggs. The highest con-
centrations of vitamin A in these foods occur during the season when an abundance
of fresh green forage is available. The lack of green forage for the winter feeding
of dairy cattle and laying fowls can to a large extent be overcome through the use
of properly cured leafy forage, yellow seeds, such as yellow corn and yellow roots.
From the practical standpoint therefore, the question of vitamin addition is
not of much importance in cattle feeding. As all grains, grain offal, pasture, roots,
etc., are rich in vitamins, there is little danger of naturally grazing farm animals
suffering from a deficiency of vitamins. The only possibility of vitamin deficiency
is in the case of indoor animals fed on rations composed mainly of artificial foods.
It is remarkable that the vitamin requirement diminishes when the ration becomes
better balanced with regard to the known constituents of food. 49 According to
McCarrison 50 if a ration be properly balanced with regard to the known constituents
of food, it is hardly possible for deficiency diseases, i.e., those due to lack of
vitamins, with the possible exception of scurvy, to occur outside a laboratory.
MINERAL DEFICIENCY AND DISEASES DUE TO MALNUTRITION IN FARM ANIMALS
The object of this section is to record a brief account of the numerous observa-
tions made on the malnutrition of animals on a mineral deficient ration and its
effect on maintenance, growth and reproduction. The deficiency of lime and phos¬
284 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY III, III.
phorus, both natural and experimental, has been the most investigated,. and many
cases of Rickets, Osteoporosis or Osteomalacia, soft bone, bent leg, etc., are to be
found in the literature. Deficiency of chlorine, iron, potassium, sodium, magnesium
and iodine also occurs in many parts of the world. In the case of a deficiency of
calcium, it has been proved that a slowing of the rate of growth, rickets and various
digestive disturbances may be induced. 51 In a long series of experiments to which
reference has already been made, Hart, McCollum and Steenbock (loc. cit.) studied
growth and reproduction in cattle on a restricted diet of various grains. It was
observed that the wheat fed animals (a diet deficient in calcium) suffered from
malnutrition. Their offspring were not carried to full term and those that were not
born dead usually died several days after birth. Meigs 52 and Hart, Steenbock and
Humphrey 53 have found that loss of calcium (in milch cows with a negative calcium
balance) has a serious effect on the condition of calves. They may be small and
weakly, or may not live. Further, there may be difficulty in getting the cows to
breed and abortion is liable to occur, but the same cows give birth to healthy, full
time calves when the ration is improved by the addition of calcium salts.
A deficiency of calcium or phosphorus in the diet leads to decreased rate of
growth in growing animals and decreased production in full grown animals. The
feeding of deficient mineral has a remarkable effect on such cases. Thus Theiler
and others 54 showed that the feeding of bone meal to stock grazing on phosphorus
deficient pasture resulted in a rate of growth nearly three times greater than that
of control animals on the same pasture without bone meal. The milk yield in this
case also increased by 40 per cent. According to a Rowett Institute experiment,
in the case of pigs on a Calcium deficient diet, the gain in weight in 124 days was
69.3 lbs. as compared with 132.8 lbs. on the same ration with the addition of cal-
cium rich salt mixture. Elliot and others 55 fed young pigs on a ration of oatmeal
bran, blood meal and potatoes with some swede turnip, " marmite " and cod liver
oil being added to prevent vitamin deficiency. The ration was markedly deficient
in calcium. The animals became unthrifty as shown by a staring coat, a tendency
to emaciation, lethargy and a stilted gait. By the end of the third month bony
deformities were evident. Post-mortem examination of the bones showed a reduced
calcium and phosphorus content, excess of osteoid tissue, and a disorganisation of
the zone of proliferation of cartilage. Control animals on the same ration with the
addition of a calcium rich salt mixture grew at the normal rate and remained in
perfect health. A very significant result has been obtained with breeding animals.
Davidson 56 in Cambridge working with sows found that deficiency of calcium was
the cause of weak litters, with high mortality after birth, becoming progressively
worse with successive generations. Breeding was impossible in the fourth genera-
MINERAL METABOLISM OF FARM ANIMALS
285
tion. It was noted that there was an absence of udder development at parturition
and an obvious lack of milk during the suckling period. In a somewhat similar
experiment with cattle at Wisconsin, Hart and others 57 found that on a ration of
ground oats and oat straw, cows failed to breed or gave birth to dead calves. These
workers calculated that for normal reproduction, there should be 0.45 part of
calcium per 100 of the ration.
Much attention has not however been paid to other minerals. McGowan and
Crichton 58 studied the subject of iron deficiency in the case of young pigs. They
found that with a deficiency of iron, the young pigs gained in weight at fully the
normal rate, but were fat and flabby. The skin was paler than normal and in some
cases the hæmoglobin was as low as 25 per cent. of the normal. The death rate was
high. As a result of experiments on animals Hoslin 59 has also suggested that
deficiency of iron may be the cause of primary anæmia in children. Waddel and
others 60 recently showed the physiological function of traces of copper in hæmoglobin
building and Elvehyem, Hart and co-worker 61 have shown the necessity of copper as
a supplement to iron in hæmoglobin formation in the pig. Orr 62 states that a diet
containing too little salt produces in cows a staring coat, lustreless eyes and a
condition of general malnutrition with a decrease in milk yield. The condition
appears to be due to a lack of chlorine, and can be rapidly cured by giving either
sodium chloride or potassium chloride. An excess of chlorine however might lead
to pathological symptoms. Thus McCollum 63 regards an inflammatory condition of
the eyes, resembling xerophthalmia which he calls "salt ophthalmia" as due to
excess of chlorine in the food.
So far we have been considering malnutrition in cattle more or less under
experimental conditions. The importance of this mineral deficiency lies however in
the fact that some deficiency diseases, due to lack of minerals, are common in all
parts of the world. Thus Marine 64 studied the curative effect of iodine on goitre by
observations on sheep in Michigan. Severe losses occurred there through goitre
with which were associated certain pathological conditions and heavy death rate in
lambs. Ennis Smith 65 in Montana found a striking case of the effect of iodine in
preventing the birth of hairless pigs. Helmer 66 in British Columbia and Torrance 67
in Canada recommended administration of potassium iodide to sows, ewes and cows
as a prophylactic measure against goitrous conditions. Numerous other experiments
on the beneficial effect of iodine on a iodine-low ration have demonstrated its value
in the dieting of farm animals.
The most important of recent contributions to the study of mineral requirement
has been made on phosphorus deficiency by a group of workers in South Africa, and
a very recent paper by Theiler and Green 68 summarises the position of aphosphorosis