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Arginine is an important amino acid for angiogenesis and vasodilation, and recent studies have established ideal amino acid ratios for maternal, placental, fetal, and mammary gland tissue growth during gestation. This study was carried out to evaluate the effects of supplementing gestation diets with arginine and/or amino acid blend (lysine, methionine, threonine, and tryptophan) on placental efficiency and piglet birth weight (BW) in hyper-prolific females. Pregnant gilts were divided into four treatment groups, namely, Control (corn-soybean meal based diet from D25 to D112), Arginine (supplemented with 1% Arg from D25 to D80); Blend (20 g of blend from D81 to D112) and Argiblend (supplemented with 1% Arg from D25 to D80 and 20 g of blend from D81 to D112 of gestation). The supplementation with Blend increased the weight of gilts at D112). The total number of piglets born, percentage of mummified fetuses, average BW, within-litter coefficient of variation in BW, percentage of low-birth-weight piglets (≤850 g or ≤1000 g), placental weight, placental efficiency and expression of vascular endothelial growth factor (VEGF) were not affected by the supplements. The supplementation with arginine decreased the number of born alive piglets and increased then percentage of stillborn piglets. The average placental weight was higher in Blend than in Control gilts. The effects of supplementation were also evaluated based on prolificacy of females categorized as either high (>14 total piglets born) and low (≤14 total piglets born). Within LowProlif group, gilts fed on the blend treatment had increased LitBW and AvgPBW compared to control gilts. LowProlif gilts supplemented with arginine also had higher AvgPBW than Control gilts. The LowProlif gilts fed on the arginine or blend diets had lower percentage ( P 0.05) of low BW piglets (≤850 g and ≤1000 g) than those fed on the control and argiblend diet. Even though gestation diets supplemented with arginine and/or an amino acid blend did not influence average piglet BW and the within-litter variation in BW, when all the litters were taken into account, the supplementation with arginine or blend increased the average BW and reduced the percentage of low-weight piglets at birth when the litter size was less than 14.

A genome-wide association study for immune response to influenza vaccination in a crossbred swine population was conducted. Swine influenza is caused by influenza A virus (FLUAV) which is considered one of the most prevalent respiratory pathogens in swine worldwide. The main strategy used to control influenza in swine herds is through vaccination. However, the currently circulating FLUAV subtypes in swine are genetically and antigenically diverse and their interaction with the host genetics poses a challenge for the production of efficacious and cross-protective vaccines. In this study, 103 pigs vaccinated with an inactivated H1N1 pandemic virus were genotyped with the Illumina PorcineSNP60V2 BeadChip for the identification of genetic markers associated with immune response efficacy to influenza A virus vaccination. Immune response was measured based on the presence or absence of HA (hemagglutinin) and NP (nucleoprotein) antibodies induced by vaccination and detected in swine sera by the hemagglutination inhibition (HI) and ELISA assays, respectively. The ELISA test was also used as a measurement of antibody levels produced following the FLUAV vaccination. Associations were tested with x(2) test for a case and control data and using maximum likelihood method for the quantitative data, where a moderate association was considered if p5×10(-5). When testing the association using the HI results, three markers with unknown location and three located on chromosomes SSCX, SSC14 and SSC18 were identified as associated with the immune response. Using the response to vaccination measured by ELISA as a qualitative and quantitative phenotype, four genomic regions were associated with immune response: one on SSC12 and three on chromosomes SSC1, SSC7, and SSC15, respectively. Those regions harbor important functional candidate genes possibly involved with the degree of immune response to vaccination. These results show an important role of host genetics in the immune response to influenza vaccination. Genetic selection for pigs with better response to FLUAV vaccination might be an alternative to reduce the impact of influenza virus infection in the swine industry. However, these results should to be validated in additional populations before its use.