Methionine deficiency in early-weaned dairy calves fed pelleted rations based on corn and alfalfa or corn and soybean proteins.

Holstein bull calves weaned at 4 wk of age were assigned to one of three replicated 4 X 4 Latin squares at 5 to 6 wk. Trials were abomasal infusion of 0, .30, .60, and either 90 (Trials 2 and 3) or 1.20 g (Trial 1) L-methionine/kg pelleted starter ration consumed. In Trials 1 and 2, ration ingredients of the ration contributed the following percentages of total crude protein: corn meal 39, alfalfa meal 48, and soybean meal 12; dry matter of rations contained 13.6 and 13.9% crude protein and .26 and .32% sulfur. Infusion of .60 g methionine in Trial 1 tended to depress excretion of nitrogen in urine and increase nitrogen retention. In Trial 2, urine nitrogen excretion and retained nitrogen responded in a quadratic fashion; infusion of .30 and .60, and either .90 (Trials 2 and 3) or 1.20 g (Trial 1) L-methionine/kg pelleted starter ration consumed. In Trials 1 and 2, ingredients of the ration contributed the following percentages of total crude protein: corn meal 39, alfalfa meal 48, and soybean meal 12; dry matter of rations contained 13.6 and 13.9% crude protein and .26 and .32% sulfur. Infusion of .60 g methionine in cretion 9%. Relationship between plasma methionine and infused methionine was linear for all trials. Methionine is the first limiting amino acid for early-weaned calves fed complete pelleted rations based on corn and either alfalfa or soybean proteins.