Lysine and Methionine Supplementation for Dairy Calves Is More Accurate through the Liquid than the Solid Diet

SIMPLE SUMMARY: Amino acids (AA) are known to be a factor limiting animals’ growth when requirements are not achieved, specially lysine (Lys) and methionine (Met). However, requirements of these AA are not well established for dairy calves. This study aimed to evaluate the performance and metabolic changes in dairy calves supplemented with Lys and Met in milk replacer (MR) or starter concentrate (SC) according to doses recommended in the literature. The supplementation with Lys and Met did not benefit dairy calves’ performance nor metabolism. However, supplementation through the MR was more efficient than SC to result in adequate daily intakes of AA. Further studies are needed to understand the negative effects of AA on calf starter intake. ABSTRACT: This study aimed to evaluate the performance and metabolic changes in dairy calves supplemented with lysine and methionine in milk replacer (MR) or starter concentrate (SC). Male Holstein calves (n = 45) were blocked and distributed in Control without supplementation (1) and; Lysine and Methionine supplementation to achieve an intake of 17 and 5.3 g/d in the SC (2) and to achieve of 17 and 5.3 g/d in the MR (3). MR was fed (6 L/d) until the 8th week of life when weaning occurred. Calves were followed until the 10th week of age. Feed intake was measured daily. Weight and body measurements were registered weekly. Blood samples were collected biweekly to evaluate the intermediate metabolism. The AA supplementation resulted in lower body weight at weaning and week 10. Calves fed SC Lys:Met had lower SC intake and lower total feed intake at weaning when compared to control. Calves fed control had higher heart girth, hip-width, and plasma glucose concentration. The supplementation with Lys and Met did not benefit dairy calves’ performance nor metabolism in this study. Supplementation through the MR was more efficient than SC to result in adequate daily intakes of AA. Further studies are needed to understand the negative effects of AA on calf starter intake.