MORPHOLOGY AND HISTOLOGY OF THE RUMEN OF GROWING HOLISH CALVES SUPPLEMENTED WITH METHIONINE ANALOG PARTIALLY METABOLIZABLE IN THE RUMEN

• Grant number: 24/22174-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Jeniffer Caroline Paterno
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Methionine analogues with partial metabolization in the rumen affect the microbial community and ruminal fermentation of adult ruminants, in addition to increasing the performance of suckling calves, as a possible response to ruminal metabolism. The objective of this study was to evaluate the morphology and histology of the rumen of growing calves supplemented with a methionine analogue partially metabolizable in the rumen. Thirty-six male Holstein calves will be used at seven days of age, allocated in blocks and distributed in three experimental diets: 1) without supplementation 2) supplementation with 8 g/d or 3) 16 g/d of methionine analogue partially metabolizable in the rumen. The study will be divided into two and during lactation the animals will be fed with 8 L/day of milk replacer, concentrate and hay. After weaning the animals will be fed with concentrate and hay. The animals will be weaned at 56 days. At 57 days of age, 18 animals will be slaughtered for collection of 1 cm1 samples of the rumen epithelium for morphological evaluation and 1 cm2 for histological analysis. The other 18 animals will be evaluated in the post-weaning phase and slaughtered when they reach 126 kg of body weight. The morphology of the epithelium will be described by the average number of papillae per cm² of wall, average area of the papillae, total area of absorptive surface per cm² of wall and representation of the ruminal papillae in the total area of absorptive surface. For histology, the number and type of cells present in the digestive epithelium will be evaluated. The data will be subjected to analysis of variance (ANOVA) by the F test with significance at P ¿ 0.05 and regression for linear and quadratic effects for the doses of the methionine analogue in the diets.