Effects of fetal programming under offspring development in beef cattle

• Ano de defesa: 2022
• Autor(a) principal: Cracco, Roberta Cavalcante
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Desempenho; Epigenética; Epigenetics; Maternal nutrition; Nellore; Nelore; Nutrição materna; Nutrigenética; Nutrigenetics; Performance
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/74/74131/tde-16032023-161733/

The production of beef cattle, for the most part, occurs in an extensive way, where the animals depend almost exclusively on the availability of forage in terms of quality and quantity. In this scenario, the fetus in the pregnant mother faces the great challenge of depending on the mother for its nutrition and development, often suffering the impact of maternal malnutrition. In turn, maternal nutrition has a great impact on the life of the individual in formation, being able to cause long-term changes in several areas, a process called fetal programming. With that, the objective of this dissertation was to evaluate the corporal performance and muscular development in steers throughout life, and the reproductive development of heifers in the rearing. For this, 126 Nellore cows were inseminated and divided into three nutritional plans: NP (control) - Not Programmed, without protein-energy supplementation; PP - Partial Programmed, protein-energy supplementation in the final third of pregnancy; and FP - Full Programmed, protein-energy supplementation during all gestation. From birth, the animals had their weight and ultrasound measurements collected. In total, 63 males and 55 females were used. The males underwent biopsy of the Longissimus muscle at 15 and 22 months for transcriptomics. During rearing, heifers were monitored for reproduction to assess the impacts of fetal programming on the development of their reproductive tract. In the first chapter of this dissertation, the growth performance of males was evaluated from birth to slaughter, at 22 months, using measurements of weight, ribeye area and backfat and rumpfat thickness, as well as the gain of these measures in the calving, rearing and feedlot periods. No significant differences were found, but trends to the difference appeared in weaning weight, ribeye area gain and average daily gain during feedlot, and gain in rumpfat thickness during calving were detected, suggesting that differences between the treatments was not as great as it could have been. In the second chapter, the effects of maternal supplementation on the epigenetics of animals were evaluated using RNA-Seq data from the Longissimus muscle. In it, no differences were observed in the expression of genes related to changes in histones and chromatin, but there were differences between the treatments and the control when looking at the regulation made by long non-coding RNAs (lncRNA). Genes regulated by lncRNA have been shown to be involved in uterine embryonic development, adipose cell differentiation, vasculogenesis, transforming growth factor beta and canonical Wnt signaling pathway, among others. Finally, in the third and last chapter, the reproductive development of females during rearing, correlation between reproductive and performance traits, and genotype-environment interactions was addressed. There were differences in weight over time, but no effect of maternal supplementation was detected on the other traits. In the correlation analyses, there was a high correlation between measurements of loin eye area and weight. In the exploratory genomic association study, one SNP per treatment was identified. In summary, the effects of fetal programming are varied and dispersed in the literature, and this dissertation brings great contributions to this field of study, from the discovery of molecular mechanisms to small phenotypic changes.