[Investigations on the sulfate concentration in milk substitutes and milk products and its effect on feces composition in calves].

In continuing investigations on effects of milk replacers with high ash and mineral contents (KAMPHUES et al., 1999a) on feces' quality and composition in calves in the present study the sulfate concentration (and its effects) in milk replacers and whey products were proved. In 13 samples of milk replacers the SO4 concentration varied between 2.4 and 6.7 g/kg dry matter, in 14 samples of dried whey products SO4- concentrations of 1.4 up to 41.8 g/kg dm were found. In general higher sulphur contents were caused by higher concentrations of sulfate. In feeding a milk replacer (6.7 g SO4/kg dm) about 20% of the consumed sulfate were excreted via feces (app. digestibility of about 80%). In experiments with elevated SO4 intake (in liquid diets: 560-1980 mg/l) the digestibility rate of sulfate decreased dose dependently (75-->65%). By analysis of milk replacers (used in previous experiments, TSCHENTSCHER, 1998) resulting in diarrhea in all treated calves unexpected SO4- concentrations were found of 16.3 and 10.2 g/kg dm. In feeding experiments (6 calves) by addition of Na2SO4 (85%) and MgSO4 (15%) sulfate concentration in the liquid diet was elevated from 560 mg to 1980 mg/l. Here the SO4 concentration in the diet and the dry matter content in calves' feces were correlated significantly (r = -0.86). Presented results on the SO4 concentration in milk replacers and the observed effects of sulfate intake on feces quality (i.e. dry matter content of feces) indicate by the first time that the SO4 content in milk replacers and dried whey products is an essential parameter when an estimation of milk replacers or whey products' quality is required.