The influence of litter birth weight phenotype on embryonic and placental development at day 30 of gestation in multiparous purebred Large White sows.

The aim of this study was to understand the intrauterine biological processes associated with the low litter birth weight phenotype in pigs. Analyses were conducted on reproductive data from a purebred Large White maternal line to identify sows (>2 parities) with repeatable high or low litter birth weight phenotype (HLBWP or LLBWP). A total of 40 sows were selected (n = 20 HLBWP and n = 20 LLBWP) and bred with semen from purebred Large White boars of proven fertility. Sows were euthanized on day 28-30 of gestation (day 29.5 ± 0.6) and samples of placenta and embryos collected. Total number of embryos (TNE), embryonic weight (EW), embryonic viability, and crown-rump (CRL) measurements were recorded, along with the ovulation rate (OR) and allantochorionic fluid volume (AFV). No significant difference was detected (P > 0.05) in OR, TNE, and number of viable embryos on day 30 of gestation between the two groups. There was no significant difference in EW (LLBWP: 0.80 ± 0.05 g; HLBWP: 0.88 ± 0.04 g, P = 0.18) or CRL (LLBWP: 21.5 ± 0.7 mm; HLBWP: 21.9 ± 0.68 mm, P = 0.46). Placental development represented by the average AFV was significantly lower in the LLBWP compared to HLBWP (LLBWP: 131 ± 9.82 mL; HLBWP: 149 ± 9.39 mL, P = 0.03). In conclusion, placental development may be the main factor causing lower BW of entire litters in LLBWP sows.

Economic comparison of an ear tag automated activity monitor for estrus detection with timed-AI in Holstein heifers.

The objective of this study was to compare the economic performance of an ear tag automated activity monitor system (AAM) versus a timed-AI (TAI) protocol in Holstein heifers. In total, 340 heifers were enrolled onto the study at 13.5 mo of age and randomly assigned to receive either an AAM (n = 170) or TAI (n = 170) protocol before breeding eligibility (D 0). Heifers in the AAM group were fitted with an ear tag AAM and bred based on high activity alert from the system. Heifers in the TAI group received a progesterone releasing intravaginal device on D -8, followed by device removal and prostaglandin on D -3 and gonadotropin-releasing hormone with TAI on D 0. In both treatments, the majority of heifers received sex-sorted semen for the first AI and conventional semen for subsequent AIs, with three opportunities to become pregnant. All heifers were diagnosed for pregnancy approximately 25 d post AI using transrectal ultrasonography, with confirmation at 30 and 45 d. Non-pregnant heifers in the TAI group, were resynchronized using the same TAI protocol. A partial budget was used to compare the costs and benefits of switching from a TAI to an AAM protocol in heifers, including protocol, labour, and rearing costs for each treatment, as well as estimated calf and milk value. Sensitivity analyses were also conducted to determine the effect of pregnancy per AI (P/AI), outsourcing AI, AAM tag cost and herd size on the net outcome. There was no difference in overall P/AI or days to pregnancy between treatments. However, number of AI was greater in the TAI than the AAM group. For the first AI, the P/AI was less in the TAI compared to the AAM group; however, the interval to first AI was less in TAI. There was minimal difference in performance for the second and third AI. There was a net gain of $11.97 per heifer when switching from a TAI to AAM protocol, due to the increased P/AI to the first AI and reduced cost of hormones. Several variables in the sensitivity analyses affected the net outcome. Considering only the first AI, switching to an AAM collar and a larger herd size all increased the net gain. Considering a greater P/AI to the first AI in the TAI group, outsourcing AI, using more AAM ear tags, and smaller herd sizes resulted in a net loss when switching from TAI to AAM. The AAM system resulted in exceptional P/AI and may be an economically viable alternative to improve heifer reproductive efficiency in herds with suboptimal P/AI to TAI.

Comparative transcriptomic analysis of porcine peripheral blood reveals differentially expressed genes from the cytokine-cytokine receptor interaction pathway related to health status.

While some research has looked into the host genetic response in pigs challenged with specific viruses or bacteria, few studies have explored the expression changes of transcripts in the peripheral blood of sick pigs that may be infected with multiple pathogens on farms. In this study, the architecture of the peripheral blood transcriptome of 64 Duroc sired commercial pigs, including 18 healthy animals at entry to a growing facility (set as a control) and 23 pairs of samples from healthy and sick pen mates, was generated using RNA-Seq technology. In total, 246 differentially expressed genes were identified to be specific to the sick animals. Functional enrichment analysis for those genes revealed that the over-represented gene ontology terms for the biological processes category were exclusively immune activity related. The cytokine-cytokine receptor interaction pathway was significantly enriched. Nine functional genes from this pathway encoding members (as well as their receptors) of the interleukins, chemokines, tumor necrosis factors, colony stimulating factors, activins, and interferons exhibited significant transcriptional alteration in sick animals. Our results suggest a subset of novel marker genes that may be useful candidate genes in the evaluation and prediction of health status in pigs under commercial production conditions.

Structural analysis of MHC alleles in an RSV tumour regression chicken using a BAC library.

The chicken major histocompatibility complex (MHC-B locus) has a strong association with resistance and susceptibility to numerous diseases. We have found a B haplotype designated WLA that associated with the regression of tumours caused by Rous sarcoma virus J strain (RSV-J). Haplotype WLA was identical to the regressive B6 haplotype when partial genotyping was performed (Poultry Science, 89, 2010, 651). We then constructed a bacterial artificial chromosome (BAC) library from a WLA homozygote chicken to evaluate the structure of this regression haplotype and compared it to those of the B6 haplotype. Comparison between WLA and B6 above 59 kb within the 167 kb, including 14 genes from BG1 to BF2, revealed 75 SNPs and 14 indels. However, several genes were identical between WLA and B6, including the BF1 and BF2 genes, which encode a class I molecule previously suggested to be related to the regression phenotype. The BLB2 gene encoding the MHC class II beta chain showed the greatest diversity, with 19 non-synonymous SNPs. A comparison of WLA and B6 haplotpyes that are associated with tumour regression and RIRa and B24 haplotypes associated with tumour progression suggests that DMA1, DMA2, BRD2, TAPBP and BLB2 genes are not involved in the intensity of RSV J tumour regression.

Genotypes of chicken major histocompatibility complex B locus associated with regression of Rous sarcoma virus J-strain tumors.

The chicken MHC-B locus affects the response to several strains of Rous sarcoma virus (RSV). We evaluated the association between haplotypes of the MHC-B locus and responses to the J strain of RSV by using an F(2) experimental resource family constructed with tumor-regressive (White Leghorn) and tumor-progressive (Rhode Island Red) chickens. The MHC-B haplotypes were determined by genotyping of the microsatellite marker LEI0258 and MHC-B locus class I alpha chain 2 (BF2). Two haplotypes in the resource family, one associated with tumor regression and one with progression, were defined by these 2 markers. To discriminate more precisely the regressive haplotype in this family, we further developed 35 SNP markers at the MHC-B locus. Information on the haplotypes revealed here should be useful for identifying chickens with regression and progression phenotypes of J-strain RSV-induced tumors.

Single nucleotide polymorphism identification, linkage and radiation hybrid mapping of the porcine pituitary adenylate cyclase-activating polypeptide type I receptor gene to chromosome 18.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with diverse biological actions. Type I PACAP receptors (PACAPR) are specific for PACAP, whereas type II and III PACAPRs are less restricted. To localize and analyse the variation of this gene, a 559-bp long intronic fragment of the porcine PACAPR gene was amplified by polymerase chain reaction and sequenced in samples from five different pig breeds. One single nucleotide polymorphism was identified and its allele frequency was determined in all five breeds. Linkage analysis in a Berkshire x Yorkshire reference family placed the PACAPR gene on chromosome 18, between SW787 and S0062 (SW787- 8.1 cM -PACAPR- 3.0 cM -S0062). Radiation hybrid mapping confirmed that the PACAPR gene was linked to SW1682 on chromosome 18 (28.8 cR(3000); LOD = 10.4).

New alleles in calpastatin gene are associated with meat quality traits in pigs.

Suggestive QTL affecting raw firmness scores and average Instron force, tenderness, juiciness, and chewiness on cooked meat were mapped to pig chromosome 2 using a three-generation intercross between Berkshire and Yorkshire pigs. Based on its function and location, the calpastatin (CAST) gene was considered to be a good candidate for the observed effects. Several missense and silent mutations were identified in CAST and haplotypes covering most of the coding region were constructed and used for association analyses with meat quality traits. Results demonstrated that one CAST haplotype was significantly associated with lower Instron force and cooking loss and higher juiciness and, therefore, this haplotype is associated with higher eating quality. Some of the sequence variation identified may be associated with differences in phosphorylation of CAST by adenosine cyclic 3', 5'-monophosphate-dependent protein kinase and may in turn explain the meat quality phenotypic differences. The beneficial haplotype was present in all the commercial breeds tested and may provide significant improvements for the pig industry and consumers because it can be used in marker-assisted selection to produce naturally tender and juicy pork without additional processing steps.

Construction of a new porcine whole-genome framework map using a radiation hybrid panel.

We have constructed a radiation hybrid (RH) map of the porcine genome using an RH panel generated by an irradiation dose of 5000-rad (Sus scrofa radiation hybrid map, SSRH map). Normal porcine aortic endothelial cells were irradiated and fused with a thymidine kinase-deficient mouse cell line, L-M (TK-). A total of 110 cell lines were selected and used for further analysis. Among 1091 microsatellite (MS) markers selected for mapping, 842 markers (77%) could be typed on the panel. The framework map comprised 342 MS markers and an additional 247 MS markers were then added to generate the whole-genome map. The average retention frequency for the data set was 30.6%. The total map length was 5596.2 centiRay (cR). Using an estimated physical length of 2718 Mbp, the average ratio between cR and physical distance over the porcine genome was estimated to be 0.49 Mb/cR.

Evidence for new alleles in the protein kinase adenosine monophosphate-activated gamma(3)-subunit gene associated with low glycogen content in pig skeletal muscle and improved meat quality.

Several quantitative trait loci (QTL) affecting muscle glycogen content and related traits were mapped to pig chromosome 15 using a three-generation intercross between Berkshire x Yorkshire pigs. On the basis of the QTL location the PRKAG3 (protein kinase, AMP-activated, gamma(3)-subunit) gene was considered to be a good candidate for the observed effects. Differences in the PRKAG3 gene sequences of the founder animals of the intercross were analyzed. The RN(-) mutation previously reported was not present in the cross but three missense substitutions and a polymorphic short interspersed element (SINE) were identified. To confirm the hypothesis that at least one of these mutations was associated with differences in meat quality, >1800 animals from several unrelated commercial lines were genotyped for the candidate substitutions and an association study was performed. The results demonstrate the presence of new economically important alleles of the PRKAG3 gene affecting the glycogen content in the muscle and the resulting meat quality. Haplotype analysis was shown to resolve the effects of PRKAG3 more clearly than analysis of individual polymorphisms. Because of their prevalence in the more common commercial breeds, the potential implications for the pig industry and consumers are considerably greater than the original discovery of the RN(-) mutation. Furthermore, these results illustrate that additional alleles of genes involved in major mutations may play a significant role in quantitative trait variation.

The Belt mutation in pigs is an allele at the Dominant white (I/KIT) locus.

A white belt is a common coat color phenotype in pigs and is determined by a dominant allele (Be). Here we present the result of a genome scan performed using a Hampshire (Belt)/Pietrain (non-Belt) backcross segregating for the white belt trait. We demonstrate that Belt maps to the centromeric region of pig Chromosome (Chr) 8 harboring the Dominant white (I/KIT) locus. Complete cosegregation between Belt and a single nucleotide polymorphism in the KIT gene was observed. Another potential candidate gene, the endothelin receptor type A gene (EDNRA), was excluded as it was assigned to a different region (SSC8q21) by FISH analysis. We argue that Belt is a regulatory KIT mutation on the basis of comparative data on mouse KIT mutants and our previous sequence analysis of the KIT coding sequence from a Hampshire pig. Quantitative PCR analysis revealed that Belt is not associated with a KIT duplication, as is the case for the Patch and Dominant white alleles. Thus, Belt is a fourth allele at the Dominant white locus, and we suggest that it is denoted I(Be).

Effect of the estrogen receptor locus on reproduction and production traits in four commercial pig lines.

We investigated the effect of the estrogen receptor (ESR) gene on growth and reproductive traits in four Large White-based commercial pig lines. A total of 9,015 litter records from 4,262 sows genotyped at the ESR locus were analyzed to determine whether ESR influenced total number born (TNB) or number born alive (NBA). Teat number (TN), test ADG, ADFI, feed:gain ratio (F/G), and ultrasonic backfat (BF) were also analyzed to determine effects of ESR. The TNB and NBA were increased per favorable allele of ESR (P < .01) with additive effects of .42 (.31) and .39 (.31) pigs/litter in the first parity (later parities), respectively. Dominance effects were near zero in parity one, but they were .16 and .14 pigs for TNB and NBA, respectively, in later parities (P < .05). A favorable additive pleiotropic effect was detected for BF (P < .001; -.11 mm per copy of the favorable litter size allele). There were no detectable effects on ADG or F/G (P > .10), although ADF was reduced 18 g/d per copy of the favorable litter size allele (P < .05). Average TN was 13.1 for pigs carrying the favorable litter size allele vs 13.2 for noncarriers (P < .05). Marker-assisted selection using ESR is warranted to increase litter size in the Large White-based lines considered here and will be of considerable economic value to pork producers.

The estrogen receptor locus is associated with a major gene influencing litter size in pigs.

Identification of individual major genes affecting quantitative traits in livestock species has been limited to date. By using a candidate gene approach and a divergent breed cross involving the Chinese Meishan pig, we have shown that a specific allele of the estrogen receptor (ER) locus is associated with increased litter size. Female pigs from synthetic lines with a 50% Meishan background that were homozygous for this beneficial allele produced 2.3 more pigs in first parities and 1.5 more pigs averaged over all parities than females from the same synthetic lines and homozygous for the undesirable allele. This beneficial ER allele was also found in pigs with Large White breed ancestory. Analysis of females with Large White breed background showed an advantage for females homozygous for the beneficial allele as compared to females homozygous for the other allele of more than 1 total pig born. Analyses of growth performance test records detected no significant unfavorable associations of the beneficial allele with growth and developmental traits. Mapping of the ER gene demonstrated that the closest known genes or markers were 3 centimorgans from ER. To our knowledge, one of these, superoxide dismutase gene (SOD2), was mapped for the first time in the pig. Analysis of ER and these linked markers indicated that ER is the best predictor of litter size differences. Introgression of the beneficial allele into commercial pig breeding lines, in which the allele was not present, and marker-assisted selection for the beneficial allele in lines with Meishan and Large White background have begun.

Klebsiella pneumoniae strain K21: evidence for the rapid secretion of an unacylated form of pullulanase.

Klebsiella pneumoniae strain PAP996 was previously shown to secrete fatty acylated, aggregated (micellar) pullulanase only after the end of exponential growth. Here we show that the closely related strain K21 secretes large amounts of unacylated, non-aggregated (monomeric) pullulanase during exponential growth. Only a small amount (less than 10%) of the secreted pullulanase was initially retained by the exponentially growing cells to be subsequently secreted in a fatty acylated, aggregated form. Despite the absence of fatty acids in secreted monomeric pullulanase, the effects of the antibiotic globomycin on pullulanase maturation indicated that all of the enzyme synthesized by strain K21 is processed by lipoprotein signal peptidase.

Molecular cloning and nucleotide sequence of the pectin methyl esterase gene of Erwinia chrysanthemi B374.

The gene encoding pectin methyl esterase (pme) has been cloned from Erwinia chrysanthemi B374. Expression of pme in Escherichia coli allowed the enzyme to be characterized. Pectin methyl esterase (PME) was found to have an apparent molecular weight of 36,000 Daltons and an isoelectric point of approximately 9.9. The structural gene was sequenced and consists of a 1098-bp open reading frame encoding a polypeptide of 39,318 Daltons, which includes an amino-terminal signal peptide. The isolation of the Erwinia gene provides a simple method for the production of PME free from depolymerizing pectinases thereby extending its potential uses.