The Effect of Plane of Nutrition on the Mineral Composition of Blood Serum, Liver, and on the Growth of Bone

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Abstract
In a slaughter experiment with Holstein bull calves, the effect of age and plane of nutrition was studied on the growth and development of bone and the micronutrient element content of blood serum and liver tissue. The calves were provided with 60 to 75, 100 and 140 to 160% of Morrison's higher total digestible nutrient allowances for growing dairy heifers; and were slaughtered at 16, 32, 48, 60 and 80 weeks of age. A parabolic relation of the physical and chemical characteristics of bone to body weight was observed. Bone from calves of the same body weight were in the same stage of development regardless of age or plane of nutrition fed. Normal bone growth continued in the underfed animals to the final slaughter age. The blood serum level of copper (60.0±5.8 meg. per 100 ml), molybdenum (5.0±0.88 meg. per 100 ml.) and manganese (0.59±0.17 mcg. per 100 ml.) did not change with age. Serum copper levels increased with a higher rate of copper consumption. The concentration of iron (184±20.8 mcg. per gm.), molybdenum (4.7 ±0.35 mcg. per gm.) and manganese (8.9±0.55 mcg. per gm.) in the liver dry matter was not affected by the age of the calf or plane of nutrition. The copper concentration in the liver dry matter decreased progressively with age up to 48 weeks of age, and increased at the higher level of copper consumption. The water content of the liver decreased progressively as the animal aged. Copyright © . .