Early preceding weaning and its effect on fetal programming of calves on performance, metabolic profile, carcass composition and meat quality of Nellore cattle.

• Grant number: 22/10479-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2023
• End date: June 30, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: Rodrigo Silva Goulart
• Grantee: Matheus Sousa de Paula Carlis
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 17/18937-0 - Earlier weaning of calves from Nellore cows and its effects on the fetal programming and on the produtive and reprodutive performance of the next progeny, AP.TEM
• Associated scholarship(s): 23/12386-2 - Effect of high-concentrate or high-forage diets on heifer, metabolism, and fetal development, BE.EP.DR

Abstract

Characteristics such as performance, carcass and meat quality are influenced by the proportion of fibers, adipocytes and fibroblasts that make up the animal's skeletal muscle tissue. During prenatal life, these cells develop by competitive processes, which are affected by the intrauterine environment through epigenetic changes. In this context, several studies have been carried out to understand how maternal nutrition through supplementation at different stages of gestation can alter fetal development and growth during postnatal life. However, aspects such as breastfeeding associated with the gestation of another calf can also interfere with fetal development, due to the partition of nutrients to meet the demands of these two physiological functions. Early weaning is a strategy that can improve the nutritional status of the cow and reduce the negative impact on fetal development, without affecting the performance of the calf that has been weaned. Currently, studies evaluating the impact of early weaning on fetal development have not been reported. Therefore, the present study aims to evaluate the effect of early or conventional weaning on growth, performance, metabolic profile, carcass characteristics and meat quality of the next progeny. Fifty-eight uncastrated Nellore males with initial body weight of 193.61 ± 21.68 kg and age of 5.12 ± 0.23 months will be used, coming from cows that were weaned at 150 or 240 days of previous lactation. The animals will be divided into two groups: non programed (NP), calves from cows that were weaned in the previous lactation with 240 days or Programmed (P) group, calves from cows that were weaned in the previous lactation with 150 days. In the rearing phase, a protein-energy supplement will be provided with an offer of 5g/kg of body weight per animal. During this period, weighing will be performed every 30 days to calculate average daily gain. Additionally, in the middle and at the end of the growing period, blood samples will be collected for analysis of metabolites (IGF-1, glucose, insulin and urea) and Longissimus thoracis muscle on the left side for histological analysis and gene expression. In the finishing phase, the entry and exit weights of the confinement will be recorded and, the performance of the animals will be monitored through the daily records generated by the scale and electronic "intergado" troughs. From the weight and consumption data, the average of daily gain and feed efficiency will be calculated. In the middle and at the end of the confinement period, a glucose tolerance test will be performed in a subsample of six animals per treatment (n = 12). Longissimus thoracis muscle samples will be collected in the middle of the feedlot period and during slaughter for gene expression analysis. At slaughter, the weight of the carcasses will be recorded for carcass yield and commercial cuts. During the cooling time of the carcasses, pH and temperature will be recorded every one hour during the first eight hours post-mortem and then every four hours until completing the 24 hours post-mortem. Meat samples will be collected for analysis of proximate composition, color, shear force, cooking losses, myofibrillar fragmentation index and sarcomere length. The expected results in this research will be earlier animals for slaughter, improving the qualitative characteristics of the meat, as well as a faster return on investment associated with a short production cycle. These results would present great potential to be disseminated in scientific journals of great impact, as well as they may be of great relevance to national livestock due to their applicability.