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Introduction: Porcine reproductive and respiratory syndrome virus (PRRSV) causes respiratory disease in piglets and reproductive disease in sows. Piglet and fetal serum thyroid hormone (i.e., T3 and T4) levels decrease rapidly in response to Porcine reproductive and respiratory syndrome virus infection. However, the genetic control of T3 and T4 levels during infection is not completely understood. Our objective was to estimate genetic parameters and identify quantitative trait loci (QTL) for absolute T3 and/or T4 levels of piglets and fetuses challenged with Porcine reproductive and respiratory syndrome virus.Methods: Sera from 5-week-old pigs (N = 1792) at 11 days post inoculation (DPI) with Porcine reproductive and respiratory syndrome virus were assayed for T3 levels (piglet_T3). Sera from fetuses (N = 1,267) at 12 or 21 days post maternal inoculation (DPMI) with Porcine reproductive and respiratory syndrome virus of sows (N = 145) in late gestation were assayed for T3 (fetal_T3) and T4 (fetal_T4) levels. Animals were genotyped using 60 K Illumina or 650 K Affymetrix single nucleotide polymorphism (SNP) panels. Heritabilities, phenotypic correlations, and genetic correlations were estimated using ASREML; genome wide association studies were performed for each trait separately using Julia for Whole-genome Analysis Software (JWAS).Results: All three traits were low to moderately heritable (10%–16%). Phenotypic and genetic correlations of piglet_T3 levels with weight gain (0–42 DPI) were 0.26 ± 0.03 and 0.67 ± 0.14, respectively. Nine significant quantitative trait loci were identified for piglet_T3, on Sus scrofa chromosomes (SSC) 3, 4, 5, 6, 7, 14, 15, and 17, and collectively explaining 30% of the genetic variation (GV), with the largest quantitative trait loci identified on SSC5, explaining 15% of the genetic variation. Three significant quantitative trait loci were identified for fetal_T3 on SSC1 and SSC4, which collectively explained 10% of the genetic variation. Five significant quantitative trait loci were identified for fetal_T4 on SSC1, 6, 10, 13, and 15, which collectively explained 14% of the genetic variation. Several putative immune-related candidate genes were identified, including CD247, IRF8, and MAPK8.Discussion: Thyroid hormone levels following Porcine reproductive and respiratory syndrome virus infection were heritable and had positive genetic correlations with growth rate. Multiple quantitative trait loci with moderate effects were identified for T3 and T4 levels during challenge with Porcine reproductive and respiratory syndrome virus and candidate genes were identified, including several immune-related genes. These results advance our understanding of growth effects of both piglet and fetal response to Porcine reproductive and respiratory syndrome virus infection, revealing factors associated with genomic control of host resilience.

Newcastle disease is a devastating poultry disease that often causes significant economic losses in poultry in the developing countries of Africa, Asia, as well as South and Central America. Velogenic Newcastle disease virus (NDV) outbreaks are associated with high mortalities, which can threaten household livelihoods, especially in the rural areas, and lead to loss of high-quality proteins in the form of meat and eggs, as well as household purchasing power. In this study, we exposed unvaccinated Ghanaian and Tanzanian chickens of six local ecotypes to velogenic NDV strains, measured NDV response traits, sequenced their DNA on a genotyping-by-sequencing platform, and performed variance component analyses. The collected phenotypes included: growth rates (pre- and post-exposure); lesion scores (gross lesion severity) in the trachea, proventriculus, intestine, and cecal tonsils; natural antibody levels; anti-NDV antibody levels at 7 days post exposure (dpe); tear and cloacal viral load at 2, 4, and 6 dpe; and survival time. Heritability estimates were low to moderate, ranging from 0.11 for average lesion scores to 0.36 for pre-exposure growth rate. Heritability estimates for survival time were 0.23 and 0.27 for the Tanzanian and Ghanaian ecotypes, respectively. Similar heritability estimates were observed when data were analyzed either separately or combined for the two countries. Survival time was genetically negatively correlated with lesion scores and with viral load. Results suggested that response to mesogenic or velogenic NDV of these local chicken ecotypes could be improved by selective breeding. Chickens that are more resilient to velogenic NDV can improve household livelihoods in developing countries.

This study is aimed at evaluating antibody responses, viral loads, viral clearance and growth rate of Tanzanian free-range local chicken (FRLC) challenged with LaSota strain of Newcastle disease virus (NDV) as indicator traits for selection of chickens for breeding with enhanced resistance to the disease and economic value. Three popular free-range local chicken ecotypes: Kuchi, Ching’wekwe and Morogoro-medium from three ecological zones of Tanzania were used for the experiments. Progenies from the breeder chickens were challenged with 107 titer of 50% egg infectious dose (EID50) of the virus at 28 days of age. The viral loads and viral clearance rates evaluated by qRT-PCR from tear samples collected at 2- and 6-days post infection (dpi) showed that Kuchi could clear NDV better than Morogoro-medium and Ching’wekwe. Anti-NDV antibody levels determined from blood samples collected at 10 dpi using ELISA showed that Kuchi ecotype expressed higher mean anti-NDV antibodies compared to Morogoro-medium and Ching’wekwe. Growth rates determined from body weights collected for 38 days from day of hatch (D0) to 10 dpi showed higher growth rate for Kuchi than Morogoro-medium and Ching’wekwe chickens. Kuchi chickens were potentially more resistant to ND compared to Morogoro-medium and Ching’wekwe. Key words: Free-range local chickens, Newcastle disease, immune response, innate resistance.

Newcastle Disease (ND) is a continuing global threat to domestic poultry, especially in developing countries, where severe outbreaks of velogenic ND virus (NDV) often cause major economic losses to households. Local chickens are of great importance to rural family livelihoods through provision of high-quality protein. To investigate the genetic basis of host response to NDV, three popular Tanzanian chicken ecotypes (regional populations) were challenged with a lentogenic (vaccine) strain of NDV at 28 days of age. Various host response phenotypes, including anti-NDV antibody levels (pre-infection and 10 days post-infection, dpi), and viral load (2 and 6 dpi) were measured, in addition to growth rate. We estimated genetic parameters and conducted genome-wide association study analyses by genotyping 1399 chickens using the Affymetrix 600K chicken SNP chip. Estimates of heritability of the evaluated traits were moderate (0.18&ndash, 0.35). Five quantitative trait loci (QTL) associated with growth and/or response to NDV were identified by single-SNP analyses, with some regions explaining &ge, 1% of genetic variance based on the Bayes-B method. Immune related genes, such as ETS1, TIRAP, and KIRREL3, were located in regions associated with viral load at 6 dpi. The moderate estimates of heritability and identified QTL indicate that NDV response traits may be improved through selective breeding of chickens to enhance increased NDV resistance and vaccine efficacy in Tanzanian local ecotypes.

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) causes respiratory disease in piglets and reproductive disease in sows. However, the interaction between host immunity and hormone homeostasis is not completely understood but piglet and fetal serum thyroid hormone (i.e., T3 and T4) levels decrease rapidly in response to PRRSV infection. Our objective was to estimate genetic parameters, identify QTL, and uncover nearby candidate genes for T3 and/or T4 levels of piglets and fetuses challenged with PRRSV2. Serum from 5-week old pigs (N=1792) at 11 days post infection (dpi) with PRRSV2 were assayed for T3 levels (piglet_T3). While serum from fetuses (N=1267) at 12 or 21 dpi from sows (N=150) challenged with PRRSV2 in late gestation were assayed for T3 (fetal_T3) and T4 (fetal_T4) levels. Animals were genotyped for 60K or 650K SNPs, heritabilities were estimated and genome wide association studies were performed for each trait separately. We found all three traits to be moderately heritable (18–28%) and the significant QTL (N=37) across several chromosomes collectively explained 24–34% of the genetic variation. A shared QTL identified for all traits on chromosome 6 contained the IL12RB2 and IFI44 genes. The largest QTL identified for both piglet_T3 and fetal_T3 on chromosome 5 contained IL17RA. A large QTL identified for piglet_T3 on chromosome 7 contained 9 MHC genes (e.g., SLA-DMA, SLA-DOA, SLA-DQA, SLA-DRA, and MHC-IA7). In conclusion, our data support the concept that there are complex interactions between thyroid hormone levels and multiple immunogenetic pathways during PRRSV infection, and that there is potential to select for pleiotropic QTL to simultaneously improve host immunity for reproductive and respiratory PRRS.

An experiment was conducted to evaluate the effects of feeding various fiber contents on the performance of chickens bred for egg or meat production from 1 to 21 d of age. The lower fiber diet was based on a traditional corn-soybean meal (SBM) diet and the higher fiber diet was formulated by the addition of 60 g/kg of both dried distillers grains with solubles (DDGS) and wheat bran in the first period of feeding and 80 g/kg of both DDGS and wheat bran in the second period of feeding to the corn-SBM base. The diets were isocaloric and were formulated to meet or exceed NRC requirements. Two lines of male chicks, Ross 308 broilers and Hy-Line W36 layers, were randomly assigned to cages with 11 replicates of 8 chicks for each of the 4 treatments. The evaluation criteria consisted of average daily gain (ADG), average daily feed intake (ADFI), feed efficiency (FE), nitrogen corrected apparent metabolizable energy (AMEn) and neutral detergent fiber (aNDF) digestibility. The higher dietary fiber diet significantly reduced broiler ADG (P≤0.01) for the 1–12 d and 1–21 d periods but had no effect on layer chick ADG, resulting in a significant interaction. Increasing dietary fiber did not have significant effects on ADFI for the 1–12 d and 1–21 d periods. Neutral detergent fiber digestibility was higher in layer chicks than broiler chicks regardless of the diet (P≤0.01), and higher dietary fiber concentration resulted in increased ileal (P≤0.01) and total (P≤0.02) aNDF digestibility, across both lines. Apparent metabolizable energy was not different (P=0.96) between lines or dietary fiber content. These results suggest that layer chicks are able to better utilize feed ingredients rich in fiber content compared to broiler chicks, possibly due to decreased ADFI and increased fiber utilization.

A survey was conducted in two sites of Senegal to determine the intra-household gender roles in the Senegal dairy cattle systems. Two surveys, baseline and longitudinal were conducted and the main survey respondents were the households heads. Households were grouped into two levels (higher or lower) of market orientation using the longitudinal household milk production data. Baseline survey results revealed that adult males (> 15 years of age) were responsible for the costs and decision making of most of the dairy related activities though less so when production was quite low. Adult males, hired males (> 15 years of age), and any other household members, except the female gender were the main labor source for the dairy activities. When comparing who received income from milk sales, income from lower market orientated households went to females for a larger proportion of households, than in higher market orientated households.