M.—AGRICULTURE. 209 
for growth. A remarkable degree of success has attended these efforts 
of the breeders. Some breeds of pigs will increase in weight from 2 lb. 
to 2 cwt. in six months. There are dairy cows which can secrete in their 
-milk as much as 10-12 lb. of solid matter per day. There are hens that 
lay 200 to 300 eggs in a year. Now, the faster the rate of growth, the 
greater must be both the absolute amount of mineral matter required 
in a given time and the proportion of mineral matter per unit of energy 
in the food. The following table shows that the percentage of mineral 
matter in the milk of different species and also the amounts relative to 
the energy values, are in proportion to the rates‘of growth. 
TABLE I. 
‘ Milk of species contains 
y Number of days in which weight of Ash Ash per 1,000 
J new-born animal is doubled. % calories. 
ke Days. Grams. Grams. 
Rial sition <ypheegsih ASO 25 3-7 
Cow .. AG rie ai 47 72 10-5 
rip... oe a: “ie 14 1-03 10:9 
Rabbit a we cit 6 2-50 15 
Hence, in modern types of animals the mineral requirements have in- 
creased pari passu with increased capacity for growth, and the danger of 
_ malnutrition through an absolute deficiency of any of the mineral elements, 
or a lack of balance of these constituents of the food, is correspondingly 
increased. As a matter of fact it is found that malnutrition due to dis- 
ordered mineral metabolism occurs most readily in those animals that are 
fc growing fastest. In experiments with both dogs and pigs it has been 
found that symptoms of rickets tend to appear earliest in those that are 
; growing most rapidly. 
Concurrently with the evolution of these faster growing types, with their 
_ greater need for each of the essential mineral elements in their food, and 
_ for a more perfect balance of these elements, there has been an increasing 
use of concentrates to support rapid growth. These concentrates, which 
consist chiefly of commercial by-products of cereal grains and tropical 
_ seeds and nuts, are markedly deficient in some of those mineral elements 
which are required for growth, or for the production of growth material. 
‘The following table compares the mineral matter of some of these 
artificial feeding stuffs with that of milk and good mixed pasture, the 
only two foodstuffs of which the mineral content corresponds 
approximately with the requirements of herbivora. 
: TABLE II. 
Y 1,000 Caloric Portions contain 
i Protein. Ca. P. Na. K. Cl! 
a Gms. Gms. Gms. Gms. Gms. Gms. 
tivated pasture . si 65:3 2-65 1-18 -69 9-58 3-52 
ws milk .. at are 51-6 1-73 1:52 “D8 2:66 1:39 
, _ Potatoes ais cas a 214 19 65 -29 4-61 +32 
Bs Maize of fr cg 28-6 02 16 08 1:18 — -0003 
- Wheat ts 8 os 35-0 13 1-18 ‘ll 1-32 “15 
It is seen from the table that foodstuffs, such as tubers and cereals, 
are deficient especially in calcium, chlorine, and sodium. Most concen- 
trates resemble cereals in their mineral composition. 
1925 P 
