Effect of candidate genes for maternal ability on piglet survival and growth

Effect of genomic regions harboring putative lethal haplotypes on reproductive performance in closed experimental selection lines of Nellore cattle

Lethal alleles are mutations in the genome that cause embryonic losses in affected homozygous embryos and, therefore, can negatively influence reproduction rates in commercial populations. Thus, this study aimed to identify genomic regions containing potential lethal haplotypes in Nellore breed; identify candidate genes located within these regions; and investigate the reproductive performance of heterozygous carriers of lethal haplotypes in Nellore cattle. Forty-five genomic regions harboring putative lethal haplotypes were identified, which overlap with 360 genes. Gene ontology analyses of these genes revealed biological processes associated with the development of sexual traits in males and females, key functions of the immune system, energy homeostasis, and embryonic development. The gene networks were involved in metabolic pathways including ovarian steroidogenesis, oocyte meiosis, and insulin secretion. Matings between carrier dam and carrier sire led to a reduction of up to -203.46% in pregnancy success probability, an increase of 275.15% in probability of pregnancy loss, 295.03% for stillbirth occurrence, and 301.40% for pre-weaning mortality when compared to non-carrier dam and sire matings. The results highlight the importance of identifying animals that are carriers of lethal haplotypes to avoid the propagation of these haplotypes in the population.

Invited review: Piglet survival: benefits of the immunocompetence

Piglet mortality has a negative impact on animal welfare and public acceptance. Moreover, the number of weaned piglets per sow mainly determines the profitability of piglet production. Increased litter sizes are associated with lower birth weights and piglet survival. Decreased survival rates and performance of piglets make the control of diseases and infections within pig production even more crucial. Consequently, selection for immunocompetence becomes an important key aspect within modern breeding programmes. However, the phenotypic recording of immune traits is difficult and expensive to realize within farm routines. Even though immune traits show genetic variability, only few examples exist on their respective suitability within a breeding programme and their relationships to economically important production traits. The analysis of immune traits for an evaluation of immunocompetence to gain a generally improved immune response is promising. Generally, in-depth knowledge of the genetic background of the immune system is needed to gain helpful insights about its possible incorporation into breeding programmes. Possible physiological drawbacks for enhanced immunocompetence must be considered with regards to the allocation theory and possible trade-offs between the immune system and performance. This review aims to discuss the relationships between the immunocompetence of the pig, piglet survival as well as the potential of these traits to be included into a breeding strategy for improved robustness.