The nutrition of ruminants grazing native and improved pastures. III.* Mineral composition of bones and selected organs from grazing cattle

Abstract

Hereford heifers grazed native pasture, native pasture which had been dressed with superphosphate, native pasture which had been dressed with superphosphate and oversown with white clover and native pasture which had been dressed with superphosphate and oversown with white clover and lotononis. The heifers were slaughtered after 12 months and the livers and kidneys were analysed for copper, zinc, molybdenum and manganese, the hearts for copper, zinc and manganese, and the livers for selenium. Samples of the spine, skull and tail, ribs, pelvis and scapula, long bones and soft tissues were analysed separately for nitrogen, fat, ash, calcium, phosphorus, magnesium, zinc and sodium.

There were significant increases in the copper, zinc, and manganese contents of the kidneys when pastures were improved, but these differences were not evident in the liver or heart or in the molybdenum contents of the liver and kidney. Selenium content of the liver declined.

The concentrations of phosphorus, calcium and magnesium in the fat-free dry matter of the spine, skull and tail, and ribs were less for cattle grazing native than for those grazing the other pastures. Differences in the composition of the pelvis and scapula, and long bones were not significant.

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*Part 11, Aust. J. Agric. Res., 29: 875 (1978).