ABSTRACTS
327
Mineral deficiencies cause unthriftiness, poor health, emaciation and disease. Early
maturing animals, because of lack of minerals in the blood, fall prey to pneumonia. Ca
and P build bone ; the former is especially important in pregnant and high producing
cows. As the foetus develops great quantities of this mineral are used in skeleton forma-
tion ; in milk secretion Ca is drawn in large amounts from the blood. A milking, preg-
nant and growing heifer is especially in need of this mineral. Early maturity is valuable
in that a heifer begins to milk as much as a year sooner; she must, however, be well
grown to prevent a shorter producing life. Cl produces hydrochloric acid which aids
greatly in digestion. Minerals not only build hardier stock, but when added to pastures
produce a more luxuriant growth. Ca is stored in the bones. If, therefore, a high
producer does not get extra Ca during her dry period there will be little or no reserve at
parturition. Such an animal may get milk fever at parturition or her bones may later
weaken so as to break easily.
Mineral deficiencies in the soil are caused by selling stock, selling milk or improper
conservation of manure. A 1000 lb. stear contains 39 .5 to 42 lb. of minerals ; the sale of
100 head of such animals a year removes about 4000 lb. of minerals from the farm. Milk
contains nearly 1% minerals. On a farm selling 400 quarts of milk daily nearly 3600 lb. of
minerals, therefore, are removed each year. For every 30 cows, nearly 1000 lb. of phos-
phoric acid and potash are lost yearly in the manure. There are other losses as minerals
leach from the pastures.
Mineral deficiencies may be corrected in two possible ways :—(1) better care and
management of pastures and (2) feeding mineral supplements to the stock.
Jamaica pastures require liming. Poor yields of poor quality fodder in pastures
require a greater amount of energy for locomotion on the part of the animals to avail
themselves of the larger quantities of food needed. These in turn require more energy for
digestion than smaller amounts of more nutritious feeds. Feeding legumes helps to
correct calcium deficiencies.
Common salt may be provided in rock form, ground form or mixed with the grain
ration at the rate of 2 lb. per 100 lb. of feed. The author suggests mixing ½ lb. of blue
stone (copper sulphate) with each 100 lb. of ground salt to prevent it from being stolen.
Bone meal provides P and Ca, usually deficient in Jamaica feeds. From 2 to 4 lb. for
each 10 lb. of common salt are recommended. Bone meal may be added at the rate of
1 lb. per 100 lb. of feed. Lime, from which Ca is obtained, should be added gradually up
to a maximum of 2 lb. per 500 lb. of feed. Ashes may be used in very small amounts.
Two mineral mixtures are suggested for cattle, sheep and horses :—
1. 10 lb. fine salt.
2 = 4 lb. bone meal.
½ = 1 lb. air-slaked lime.
2. 10 lb. fine salt.
1½= 3 lb. bone meal.
½ lb. air-slaked lime.
½ lb. ashes.
[J.N.W.]
The nutritional requirements of dairy cows. P. A. CAMPBELL (1939)
Holstein-Friesian World 36, 1328
F ARM grown feeds can be marketed through dairy cows at a better price if supplemented
by feeds from other sources in order to balance the ration. Nutrients consumed
by the cow are used for body maintenance, energy and milk production. A cow of
1,200 lb. body weight yielding 10.000 lb. of milk yearly produces 2½ times the dry weight
in the milk as that of her body. Feeding involves (1) what are the food requirements
and (2) how can they be provided. A knowledge of the nutrients concerned is there-
fore essential.
Protein.—Protein contains nitrogen which is broken up during digestion into at
least 23 products, amino acids. These go into body and milk proteins. Furthermore,
in the cows' digestive system bacteria in great numbers use this protein to build their
own bodies which are, probably, later digested by the cow. Protein quality is the
property of a protein to supply the specific amino acids, the consuming animal most
needs. Inherent high producers require higher quality proteins ; inherent low producers
drop their production until a balance results with the quality requirements for protein.