Sulfate incorporation into organic bone matrix of the tibiotarsus of broiler chicks is reduced by excess dietary methionine
1995
Frankel, T.L.
Two experiments were conducted in broiler chicks to determine whether dietary imbalances of sulfur amino acids (SAA), vitamin A, or interactions between the two nutrients could influence organic bone matrix metabolism measured with L-[35S]-methionine. In the first experiment, in vivo incorporation of 35S into the tibiotarsal bone matrix of 2-wk-old birds was unaffected by vitamin A treatment of 10 and 100 times the requirement when compared with that of birds receiving recommended amounts of vitamin A. However, 35S incorporation was significantly reduced by increasing the SAA concentration of the diet to 1.5 times the requirement relative to lysine. In the second experiment, in vitro incorporation of 35S, derived from L-[35S]methionine, into bone matrix was reduced in birds consuming a diet containing 1.5 times the methionine requirement relative to lysine (Diet HS) when compared with those receiving .75 (Diet LS), 1.0 (Diet NS), or 1.25 (Diet MS) times the requirement. Birds consuming Diet LS incorporated significantly more 355 into organic bone matrix than birds consuming the other three diets. Although the ratio of SAA to lysine was that recommended (.76:1), on a weight basis the concentration of SAA in diet NS was relatively high (11.48 g/kg diet) compared with the NRC (1984) recommendation of 9.3 g/kg diet. The results show that excess SAA can affect organic bone matrix metabolism and suggest that SAA may play a role in the etiology of tibial dyschondroplasia. They also indicate the importance of distinguishing between nutrient content of the diet expressed as a ratio and that expressed on a weight basis.
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