Protein intake and its relationship to urinary calcium excretion in the preruminant lamb

Abstract

Preruminant male crossbred lambs, aged 1-2 days at the start of the experiment, were used. Twenty-four lambs were bottle-fed for an experimental period of 21 days in a 4 x 3 factorial experiment (with unequal replications). The sole source of protein in the milk replacers was casein, supplemented with DL-methionine, to supply either 10, 20, 30 or 40% of the total dietary energy as protein. At each protein level there were three levels of Ca to represent 50% (low), 100% (medium) and 200% (high) of the Ca concentration of ewes' milk (taken to be 360 mg MJ-1 gross energy). The Ca:P ratio in all diets was 1.1:l. The daily intake of gross energy was controlled at 1046 kJ kg-0.73. Nitrogen, Ca and P balances were determined during the last seven days of the experiment. There was no significant effect of protein intake, or of Ca intake, on the daily urinary Ca excretion, which was uniformly low (n = 24; mean, 1.67 � 0.25 mg kg-1).