BODY GROWTH AND RUMINAL DEVELOPMENT OF HOLISH CALVES SUPPLEMENTED WITH METHIONINE ANALOGUE (HMBi) PARTIALLY METABOLIZABLE IN THE RUMEN

• Grant number: 23/14360-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2024
• End date: February 28, 2027
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Pedro Henrique Cavalcante Ribeiro
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Methionine analogues with partial metabolism in the rumen can increase the availability of the amino acid in the body and affect the microbiota and rumen fermentation. The objective is to evaluate body growth and ruminal development of calves supplemented with methionine analogue partially degraded in the rumen (HMBi). 36 Holstein calves (18 castrated males and 18 females) will be used at seven days of age, allocated in blocks and distributed on two experimental diets: 1) without supplementation or 2) supplementation with HMBi. During lactation, the animals will be fed 6L/day of milk and concentrate. After weaning, the animals will be fed with concentrate and chopped Tifton 84 (Cynodon dactylon) hay. HMBi will be provided daily, allowing intake of 6.5 g/day of methionine. Nutrient intake and fecal score will be assessed daily. Weight and body measurements will be measured every 7 days. Blood metabolites and plasma amino acid profile will be described at weaning and at the end of the experiment. Titanium dioxide (TiO2) will be used for digestibility testing and spot urine collections will allow determination of nitrogen balance and estimation of microbial protein synthesis. Six male calves will be slaughtered after weaning and at the end of the study. Fermentation parameters in rumen fluid, morphology and histology of rumen and cecum epithelia will be determined. The data will be statistically analyzed using PROC MIXED and GLM from SAS (2003), using a mixed model. The F test at 5% significance will be used to compare means. Repeated measures data will be analyzed with the REPEAT feature.