Nutrient digestibility in the total tract of Holstein calves supplemented with doses of methionine analogue partially metabolizable in the rumen

• Grant number: 24/22243-7
• 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: Marcela Resende Mecchi
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The use of roughage in the diet of growing calves allows greater rumen development and nutrient digestibility. Partially metabolizable methionine in the rumen favors fibrolytic microorganisms in adult animals, enhancing the use of roughage in diets. The objective is to evaluate the digestibility of nutrients in the digestive tract of calves supplemented with methionine analogue partially metabolizable in the rumen. 36 male Holstein calves will be used at seven days of age, allocated in blocks and distributed into three diets: 1) 0g/d 2) 8g/d or 3) 16 g/d of methionine analogue partially metabolizable in the rumen. During lactation, the animals will be fed 8L/day of Tifton 85 (Cynodon dactylon) replacer, concentrate and hay. After weaning, at 56 days, they will be fed concentrate and hay. Two digestibility tests of ten consecutive days will be carried out: breastfeeding - 41 to 50 days of age; post-weaning: 91 to 100 days of age of the animals, following the ratio of 10 g of titanium dioxide (TiO2)/kg of concentrate consumed daily.The use of roughage in the diet of growing calves allows greater rumen development and nutrient digestibility. Partially metabolizable methionine in the rumen favors fibrolytic microorganisms in adult animals, enhancing the use of roughage in diets. The objective is to evaluate the digestibility of nutrients in the digestive tract of calves supplemented with methionine analogue partially metabolizable in the rumen. 36 male Holstein calves will be used at seven days of age, allocated in blocks and distributed into three diets: 1) 0g/d 2) 8g/d or 3) 16 g/d of methionine analogue partially metabolizable in the rumen. During lactation, the animals will be fed 8L/day of Tifton 85 (Cynodon dactylon) replacer, concentrate and hay. After weaning, at 56 days, they will be fed concentrate and hay. Two digestibility tests of ten consecutive days will be carried out: breastfeeding - 41 to 50 days of age; post-weaning: 91 to 100 days of age of the animals, following the ratio of 10 g of titanium dioxide (TiO2)/kg of concentrate consumed daily.The use of roughage in the diet of growing calves allows greater rumen development and nutrient digestibility. Partially metabolizable methionine in the rumen favors fibrolytic microorganisms in adult animals, enhancing the use of roughage in diets. The objective is to evaluate the digestibility of nutrients in the digestive tract of calves supplemented with methionine analogue partially metabolizable in the rumen. 36 male Holstein calves will be used at seven days of age, allocated in blocks and distributed into three diets: 1) 0g/d 2) 8g/d or 3) 16 g/d of methionine analogue partially metabolizable in the rumen. During lactation, the animals will be fed 8L/day of Tifton 85 (Cynodon dactylon) replacer, concentrate and hay. After weaning, at 56 days, they will be fed concentrate and hay. Two digestibility tests of ten consecutive days will be carried out: breastfeeding - 41 to 50 days of age; post-weaning: 91 to 100 days of age of the animals, following the ratio of 10 g of titanium dioxide (TiO2)/kg of concentrate consumed daily.The TiO2 will be packed in a paper cartridge and applied with a metal probe to the animals' esophagus at 9:00 am between d1 and d9, and the feces will be collected directly from the rectal ampoule between d6 and d10, at different times: 8:00 am, 10:00 am, 12:00 pm, 2:00 pm and 16:00. Composite samples of feces, leftovers and food subjected to chemical composition determination to estimate nutrient digestibility coefficients. The data will be submitted to SAS PROC MIXED for a randomized block design. The F test and PROC REG will be used with a significance of P¿0.05 for linear and quadratic effects of doses of the methionine analogue.