Methionine Deficiency in Early-Weaned Dairy Calves Fed Pelleted Rations Based on Corn and Alfalfa or Corn and Soybean Proteins

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Abstract
Holstein bull calves weaned at 4 wk of age were assigned to 1 of 3 replicated 4 x 4 Latin squares at 5 to 6 wk. Trials were abomasal infusion of 0, 0.30, 0.60 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 0.26 and 0.32% S. Infusion of 0.60 g methionine in Trial 1 tended to depress excretion of N in urine and increase N retention. In Trial 2, urine N excretion and retrained N responded in a quadratic fashion; infusion of 0.30 and 0.60, and either 0.90 (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 0.26 and 0.32% S. Infusion of 0.60 g methionine in cretion 9%. Relationship between plasma methionine and infused methionine was linear for all trials. Methionine is the 1st limiting amino acid for early-weaned calves fed complete pelleted rations based on corn and either alfalfa or soybean proteins.