Fertility and longevity, major factors affecting the economic performance of dairy herds, are influenced by management and genetics. This study determined the reproductive performance and survival of Chinese Holstein cows in a large, modern dairy farm in central China using two complementary datasets. In Dataset 1, fertility and culling records were obtained from 1430 cows calving in 2008; in Dataset 2, all calving episodes during 2005 and 2006 were recorded (n = 1540) and the subsequent survival and reasons for death or culling of all female calves born during this period were monitored. In Dataset 1, the mean ages at first breeding and first calving for heifers were 18.7 ± 2.6 and 29.3 ± 3.6 months, respectively. Cows (lactations 1–10) were first inseminated at 110 ± 49 days after calving (mean ± s.d.), conceived at 185 ± 103 days and required 2.3 ± 1.6 services per conception with a first service conception rate of 34%. Reproduction performance was lower in the first lactation, with the best fertility in autumn-calving cows. In Dataset 2, 601 live-born heifers were monitored from birth until first calving. Of these, 521 (87%) were inseminated at least once and 502 (84%) calved once, but only 68% of the starting population calved successfully for a second time. The main reasons for culling in both datasets were poor fertility, disease and lameness. Improved management strategies to avoid calving cows in the spring and so offset the adverse effects of summer heat stress together with increased emphasis on selection for good fertility and conformation traits would increase future profitability.

According to Mendelian heredity laws, the sex ratio of a given chicken population during hatching is expected to be 1:1. In this study, we collected 432 chicken embryos that died during the first week of incubation from 5 different breeds. The sexes of the early-dead embryos were determined by using the previously described molecular sexing technique of double PCR. The female-to-male sex ratio was analyzed for departure from the expected 1:1 sex ratio by chi(2) testing. These results showed that the number of female dead embryos was significantly greater than that of males in the Hubei local breeding stock, Zhusi, and Hy-line Variety Brown (P < 0.05, P < 0.01, P < 0.01 respectively), with observed female-to-male sex ratios of 1.40:1, 2.03:1, and 2.22:1, respectively. Two other Chinese local breeds (the Yellow chicken and the Aijiaohuang chicken) also showed altered sex ratios, although the differences were not significant. Altogether, these results indicated that female chickens were more likely than male chickens to die at the early stages of incubation.

Alpha-(1,2)-fucosyltransferase (FUT1) gene has been identified as a candidate gene for regulating the expression of Escherichia coli F18 receptor gene (ECF18R) which promotes adherence of Enterotoxigenic (ETEC) and Verotoxigenic (VTEC) Escherichia coli (E. coli) via F18 fimbriae. In order to illustrate the polymorphisms of FUT1 and their effects on resistance to natural infection by Porcine Respiratory and Reproductive Symdrome Virus (PRRSV) and Haemophilus parasuis, the distributions of different genotypes and the relative risks of disease incidence in pigs were investigated. A total of 1,041 pigs representing three European breeds (Duroc, Landrace and LargeWhite), five Chinese local breeds (Wild pig, Small MeiShan, QinPing, JinHua, and JianLi) and three commercial populations (LargeWhite × JianLi, Duroc × Landrace × LargeWhite and Duroc × wild pig) were selected to analyze the genotype of the FUT1 gene by PCR-RFLP. Only the GG genotype associated with susceptibility to ECF18 bacteria was detected in Chinese local pig breeds and a population of LargeWhite × JianLi, while the AA genotype which confers resistance to ECF18 was detected in two European breeds (Duroc and LargeWhite), two populations of Duroc × wild pig and Duroc × Landrace × LargeWhite. Regarding relative risk of incidence, Duroc × Landrace × LargeWhite with genotypes GG or AG showed greater relative risk (OR = 2.040, P = 0.025; OR = 1.750, P = 0.081, respectively) than those with genotype AA during natural infection by both PRRSV and Haemophilus parasuis. It can be concluded that the mutation of FUT1 gene might play a role in pig infection by multi-pathogens, and that AA may be a favourable genotype for increasing the resistance to disease.

It is necessary that genetic markers or biomarkers can be used to predict resistance towards a wide range of infectious diseases. In the present study, we estimated the potential markers and measured their relationship with heritabilities of a wide range of immune traits. Polymorphisms in exon 13 of Mx1, intron 25 of BAT2 and intron 3 of CXCL12 were identified by sequencing, and the genotypes were analyzed by PCR-RFLP in a resource population composed of 352 pure breed Landrace piglets at days 0, 17 and 32 after birth. Associations of single-nucleotide polymorphisms (SNPs) in these genes with a variety of immunological traits and antibody levels for pig reproduction and porcine respiratory syndrome virus (PRRSV), pseudorabies virus (PRV) and classical swine fever virus (CSFV) were performed. The performance of GG genotype of BAT2 on hemoglobin concentration (HBG) and hematocrit (HCT) of piglets at day 0 was significantly higher than that of the AA and AG individuals. For Mx1, compared with CT genotype, the pigs with TT or CC generated more PRRS antibody at day 0. The piglets with CT genotype had highly significant difference of PRV antibody from those with CC and TT genotypes at day 0. And the piglets with CC genotype had higher level red blood cell count (RBC), hemoglobin concentration (HBG) and hematocrit (HCT) than those with CT and TT genotypes at day 17. For the C7462G SNP in the intron 3 of CXCL12, the PRV antibody level of piglets with the CG genotype were higher than that of piglets with CC and GG genotypes at day 17, and the mean corpuscular volume (MCV) of GG piglets were larger than that of CC and CG individuals at day 0. At the locus 7331 bp in the intron 3 of CXCL12, there were significantly differences of mean corpuscular hemoglobin concentrations (MCHC) at day 0 and white blood cell count (WBC) at day 32, which showed the trend GG or AG>AA, AA>AG or GG, respectively. The pigs with AA or GG genotype had more platelet distribution width (PDW), mean platelet volume (MPV) and platelet-large cell ratio (PLR) at day 17 than those with AG. The results of this study indicated that polymorphisms in Mx1, BAT2 and CXCL12 genes were significantly associated with the immunological traits in Landrace piglets and had potential application value for marker-assisted selection of pig breeding with disease resistance.