Gastrointestinal tract development of Holstein calves supplemented with doses of partially rumen metabolizable methionine analogue

• Grant number: 25/04435-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Maria Eduarda Pizzo Silva Ferreira
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The enhanced development of the digestive tract in transition calves ensures better production rates after weaning by making the rumen suitable for the fermentation and absorption of solid feed. Partially metabolizable methionine analogues in the rumen increase the concentration of ruminal short-chain fatty acids, which stimulate body development and tend to improve fiber digestion in adult animals. The objective of this study was to evaluate the development of the gastrointestinal tract (GIT) in Holstein calves supplemented with partially metabolizable methionine analogues in the rumen. Thirty-six male Holstein calves, seven days of age, will be used, allocated in blocks, and assigned to three diets: 1) 0 g/d, 2) 8 g/d, or 3) 16 g/d of partially metabolizable methionine analogue in the rumen. During lactation, the animals will be fed 8 L/day of milk replacer, concentrate, and Tifton 85 hay (Cynodon dactylon). After weaning at 56 days, they will be fed concentrate and hay. At 57 days of age, 18 animals will be reduced, while 18 will be slaughtered when they reach an average body weight of 126 kg, a metric defined for the calf category. After slaughter, the GIT portions will be separated, and the rumen, reticulum, omasum, abomasum, intestine, and cecum will be weighed both full and empty. The epithelium will be collected to evaluate dry matter. Food consumption will be related to the development of the GIT in the animals. The data will be subjected to analysis of variance (ANOVA) using the F test, with significance at P ¿ 0.05, and regression analysis for linear and quadratic effects of the doses of the methionine analogue in the diets. (AU)