Milk replacers containing a soybean protein concentrate for preruminant lambs: interrelationships between methionine, cystine and choline

Abstract

Preruminant male crossbred lambs, aged 2-5 days at the start of the experiment, were fed on milk replacers containing a soybean protein concentrate (as the sole source of protein) to supply 25 % of the total dietary energy as protein. The minimum intake of methionine plus cystine (M+C) that was coincident with maximum nitrogen balance was estimated (mean¦s.e.) at 38.5¦1.8 mg/100 kJ diet (equivalent to 3.6¦0.2 g sulfur amino acids/16 g nitrogen). When the concentration of M+C was raised to this level by supplementation with DL-methionine, the addition of choline chloride, in amounts to give final concentrations varying from approximately one-seventh up to twice the concentration in cows' milk, did not affect nitrogen balance. The maximum replacement value of cystine for methionine (as judged by the effect on nitrogen balance), in milk replacers adequately supplen~ented with choline chloride and sulfur amino acids, was 47% on a weight basis, or 52% when calculated on the basis of moles of sulfur.