Dairy calves limiting amino acids metabolism: optimun levels for maximun performance and route of administration

Abstract

The objective of this study is to evaluate the concentration of essential amino acids (lysine and methionine) considerede in the literature as ideal, according to the route of administratio (milk replacer MR or concentrate), and its association with glutamate supplementation to calves in two milk-feeding systems: conventional or programmed. In Experiment 1 a survey will be conducted to knowlegd the amino acid composition of the main MR comercialized in Brazil. In experiments 2 and 3, 45 Holstein calves will be utilized in a randomized block design to evaluate the following treatments: 1) Control: no supplementation; 2) Lysine supplementation (17 g/d) and methionine (5.3 g/d) with corrections made based on the MR analysis; 3) Lysine supplementation (17g/d) and methionine (5.3 g/d), with adjustments made based on initial analysis of the concentrate. The difference between these experiments will be the milk-feeding system: in experiment 2 animals will receive 4L/d, while in experiment 3 animals will be submitted to the programed milk-feeding system (4L/d until the 2nd.week; 8L/d from the 3rd. the 6th. week; 4L/d from 6 th to 8 th. weeks). In Experiment 4 the same design will be used to assess teh effects in conventional feeding system, the following treatments: 1) Control: no supplementation; 2) MR supplemented with Lysine (17g/d) and methionine (5.3 g/d) + 1% DM basis of product containing 10% of glutamate and glutamine, 3) MR supplemented with Lysine (17g/d) and methionine (5.3 g/d) + 0.6% DM basis of product containing 10% of glutamate and glutamine. The animals will be allocated to individual shelters, with free access to water and initial concentrate. Calves will be weighted and growth measurement taken. In weeks 2, 4, 6, 8 and 10 of life blood samples will be taken for determination of metabolites as markers of animal protein status (albumin, total protein, urea-N), energy status (glucose, beta-hydroxybutyrate and B-hydroxybutyrate), bone growth (alkaline phosphatase) and muscle growth (creatinine) and spot urine collection for analysis of creatinine and purine derivatives to estimate microbial protein production. (AU)