Genetic improvement of sow lifetime reproductive performance has value from both the economic perspectives of pork producers and the pork industry, but also from the perspective of ethical and animal welfare concerns by the general public. Genetic potential for piglets produced from individual litters is a primary determinant of lifetime prolificacy, but females must be able to sustain productivity without injury or death beyond the achievement of positive net present value. Evidence exists for between- and within-line genetic variation in sow lifetime performance, suggesting that improvements may be made by both line choices and genetic selection within lines. However, some of the same barriers to accurate within-line selection that apply to individual litter traits also present challenges to genetic selection for sow lifetime prolificacy: generally low heritabilites, sex-limited expression, expression after the age that animals are typically selected, and unfavorable genetic correlations with other traits in the profit function. In addition, there is an inherent conflict within the genetic nucleus herds where selections take place between the goal of shortened generation interval to accelerate genetic progress and the expression of sow lifetime traits. A proliferation in the industry of commercial multipliers with direct genetic ties and routine record flows to genetic nucleus herds provides a framework for accurate estimates of relevant genetic variances and covariances, and estimation of breeding values for sow lifetime traits that can be used in genetic selection.

Objective —To evaluate the associations between 14 biological candidate genes and scrotal hernias in pigs. Animals —1,534 Pietrain-based pigs, including 692 individuals from 298 pig families and 842 male pigs without family information. Procedures —Pigs were classified as affected or unaffected for scrotal hernias. Single nucleotide polymorphisms of candidate genes were analyzed via PCR assays and genotyped. Statistical analyses were performed on the family-trio and the case-control data. Results —2 genes involved in collagen metabolism (homeobox A10 [ HOXA10 ] and matrix metalloproteinases 2 [ MMP2 ]) and 1 gene encoding zinc finger protein multitype 2 ( ZFPM2 , important in the development of diaphragmatic hernia) were significantly associated with hernias. Pigs with these genotypes had high odds of developing scrotal hernias in the case and control groups (2 ZFPM2 variants: odds ratio, 4.3 [95% confidence interval, 2.78 to 6.64] and 4.45[95%confidenceinterval,2.88to6.88]). Anothergene, collagentypeII A 1( COL2A1 ),was potentially involved in hernia development. Conclusions and Clinical Relevance — HOXA10, ZFPM2 , MMP2 , and COL2A1 could have important roles in pig hernia development and potentially be useful for marker-assisted selection in the pig industry. Impact for Human Medicine —Pigs are used for the study of many human diseases because of their physiologic similarities. Genes associated with scrotal hernias in this study may be directly used in understanding the molecular mechanisms underlying this defect in humans.

Scrotal hernia in pigs is a complex trait likely affected by genetic and environmental factors. A large-scale association analysis of positional and functional candidate genes was conducted in four previously identified genomic regions linked to hernia susceptibility on Sus scrofa chromosomes 2 and 12, as well as the fifth region around 67 cM on chromosome 2, respectively. In total, 151 out of 416 SNPs discovered were genotyped successfully. Using a family-based analysis we found that four regions surrounding ELF5, KIF18A, COL23A1 on chromosome 2, and NPTX1 on chromosome 12, respectively, may contain the genetic variants important for the development of the scrotal hernia in pigs. These findings were replicated in another case-control dataset. The SNPs around the ELF5 region were in high linkage disequilibrium with each other, and a haplotype containing SNPs from ELF5 and CAT was highly significantly associated with hernia development. Extensive re-sequencing work focused on the KIF18A gene did not detect any further SNPs with extensive association signals. These genes may be involved in the estrogen receptor signaling pathway (KIF18A and NPTX1), the epithelial-mesenchymal transition (ELF5) and the collagen metabolism pathway (COL23A1), which are associated with the important molecular characteristics of hernia pathophysiology. Further investigation on the molecular mechanisms of these genes may provide more molecular clues on hernia development in pigs.

Knowledge of the extent and range of linkage disequilibrium (LD), defined as non-random association of alleles at two or more loci, in animal populations is extremely valuable in localizing genes affecting quantitative traits, identifying chromosomal regions under selection, studying population history, and characterizing/managing genetic resources and diversity. Two commonly used LD measures, r(2) and D', and their permutation based adjustments, were evaluated using genotypes of more than 6,000 pigs from six commercial lines (two terminal sire lines and four maternal lines) at ~4,500 autosomal SNPs (single nucleotide polymorphisms). The results indicated that permutation only partially removed the dependency of D' on allele frequency and that r(2) is a considerably more robust LD measure. The maximum r(2) was derived as a function of allele frequency. Using the same genotype dataset, the extent of LD in these pig populations was estimated for all possible syntenic SNP pairs using r(2) and the ratio of r(2) over its theoretical maximum. As expected, the extent of LD highest for SNP pairs was found in tightest linkage and decreased as their map distance increased. The level of LD found in these pig populations appears to be lower than previously implied in several other studies using microsatellite genotype data. For all pairs of SNPs approximately 3 centiMorgan (cM) apart, the average r(2) was equal to 0.1. Based on the average population-wise LD found in these six commercial pig lines, we recommend a spacing of 0.1 to 1 cM for a whole genome association study in pig populations.

ContentsInformation is lacking as to the timing and cause of sows that repeatedly have low litter size over several parities. Sows evaluated for the present study had at least two parities either small ≤7 (SL) or normal ≥12 (NL) litter size. Following breeding of sows with contemporary boars, reproductive tracts were obtained on day 30 of gestation. There was no difference (p > 0.10) between SL and NL sows in the number of CL, embryo weight or placental length. The total number of embryos and embryonic survival tended to be lower (p < 0.10) in SL sows compared with NL sows, but there were 5.1 less viable embryos (p < 0.03) in SL. Results indicate that time of conceptus loss in SL sows was variable throughout gestation.

The objective was to evaluate whether addition of EAZI-BREED CIDR Cattle Inserts (CIDR) to the Ovsynch program increases first service pregnancy rate (PR) in lactating dairy cows. The study was conducted in 5 dairies in Central Mexico. Cows were inseminated from June through September, 2001. Within trial site and within parity, cows were assigned to either an Ovsynch (n=255) or an Ovsynch-CIDR group (n=255) for their first service. Ovsynch was initiated at 50±3 d postpartum with an injection of 100 μg of GnRH (2 mL, i.m.; CYSTORELIN), an injection of 25 mg of PGF2α (5 mL, i.m.; LUTALYSE Sterile Solution) 7 d later, a second 100 μg injection of GnRH 48 h later, and timed insemination 8 to 20 hours after the second GnRH injection. Ovsynch-CIDR cows received the same treatments but also received a CIDR Insert (1.38 g of progesterone) which was administered with the first GnRH injection and removed 7 d later at the PGF2α injection. Cows were palpated for pregnancy 40 to 45 d after timed insemination. An interaction between treatments and parity was detected (P=0.023). The interaction indicated that PR was increased for Ovsynch-CIDR compared to Ovsynch in primiparous cows (38.2% and 20%, respectively; P=0.024) but no differences were detected in multiparous cows (22.3% and 27.5%, respectively; P=0.375). A subset of cows (n=466) was classified as anestrus or cyclic based on progesterone concentrations of two blood samples collected 7 d prior to and at the first GnRH injection. For anestrous cows, PR was 18.8% for Ovsynch (6/32) and 18.4% for Ovsynch-CIDR (7/38). For cyclic cows, PR was 23.5% for Ovsynch (47/200) and 29.1% for Ovsynch-CIDR (57/196). Such effects were further subdivided according to parity but none were significant. Addition of CIDR increased first service pregnancy rates of primiparous but not multiparous lactating dairy cows submitted to an Ovsynch program. Because cows were inseminated during summer, heat stress might have affected embryonic survival but the study was not designed to specifically address such an effect.

Journal Article Rapid communication: linkage mapping of the porcine Agouti gene Get access K. S. Kim, K. S. Kim *Department of Animal Science, Iowa State University, Ames 50011, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar E. A. Mendez, E. A. Mendez *Department of Animal Science, Iowa State University, Ames 50011, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar S. Marklund, S. Marklund *Department of Animal Science, Iowa State University, Ames 50011, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar A. C. Clutter, A. C. Clutter †Department of Animal Science, Oklahoma State University, Stillwater, 74078 Search for other works by this author on: Oxford Academic PubMed Google Scholar D. Pomp, D. Pomp ‡Department of Animal Science, University of Nebraska, Lincoln, NE 68583 Search for other works by this author on: Oxford Academic PubMed Google Scholar M. F. Rothschild M. F. Rothschild *Department of Animal Science, Iowa State University, Ames 50011, USA 3Correspondence. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 78, Issue 5, May 2000, Pages 1395–1396, https://doi.org/10.2527/2000.7851395x Published: 01 May 2000 Article history Received: 15 April 1999 Accepted: 19 November 1999 Published: 01 May 2000

Journal Article Rapid communication: assignment of the alpha-1-microglobulin bikunin precursor (AMBP) gene to porcine chromosome 1 via a new PCR-based polymorphism Get access M. J. Allen, M. J. Allen 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar S. Sasaki, S. Sasaki 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar M. J. Diederich, M. J. Diederich 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar J. V. Yelich, J. V. Yelich 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar R. D. Geisert, R. D. Geisert 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar A. C. Clutter A. C. Clutter 3Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA 2To whom correspondence should be addressed. (Phone: 405/744-6070; fax: 405/744-7390; E-mail: accosu@okstate.edu). Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 77, Issue 3, March 1999, Pages 789–790, https://doi.org/10.2527/1999.773789x Published: 01 March 1999 Article history Received: 23 July 1998 Accepted: 16 December 1998 Published: 01 March 1999

Plasma cholecystokinin-8 (CCK-8) was studied in pigs with divergent genetic potential for feed intake. Differences in feed intake resulted from selection for either fast (line F) or slow (line S) postweaning gain. The hypothesis was that the relatively lesser feed intake in S versus F may be attributable, in part, to greater circulating concentrations of the putative satiety hormone CCK-8. In Experiment 1, barrows from F (n = 23) and S (n = 19) were used to determine changes in CCK-8 associated with ad libitum feed consumption. Blood samples were collected after overnight feed deprivation, then periodically during a 2-hr feeding period. Averaged across sampling times, concentration of CCK-8 tended to be greater (P = 0.07) in S (6.70 pmol/l) than in F (5.06 pmol/l). Concentration of CCK-8 per unit of feed consumed (CCK-8/cumulative feed intake) was greater (P < 0.01) in S than in F during the first 30 min of the feeding period. In Experiment 2, plasma concentrations were determined for nine pairs (F, S) of the same barrows allowed an amount of feed equal to the previous ad libitum intake of the S barrow in the pair. Averaged across times, the difference between CCK-8 concentrations of S (11.65 pmol/l) and F (7.94 pmol/l) barrows was not significant (P = 0.18). A greater concentration of CCK-8 per unit of feed consumed in S than in F supports the hypothesis that satiety effects of CCK-8 may play a role in genetic differences between the lines for feed intake.

Journal Article Rapid communication: the cholecystokinin type-A receptor (CCKAR) gene maps to porcine chromosome 8 Get access A. C. Clutter, A. C. Clutter 4Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA 2To whom correspondence should be addressed: phone: 405-744-6070; fax: 405-744-7390; E-mail: accosu@okway.okstate.edu. Search for other works by this author on: Oxford Academic PubMed Google Scholar S. Sasaki, S. Sasaki 4Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar D. Pomp D. Pomp 4Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 76, Issue 7, July 1998, Pages 1983–1984, https://doi.org/10.2527/1998.7671983x Published: 01 July 1998 Article history Received: 01 December 1997 Accepted: 17 March 1998 Published: 01 July 1998

The objective of this study was to identify genomic regions associated with postweaning average daily gain (ADG) in swine. Two families were produced using sires obtained from the cross of lines divergently selected for high and low growth rate. Sires were mated to 29 unrelated dams that produced 124 and 115 offspring. Average daily gain was recorded for every individual; mean ADG was .593 +/- .007 kg/d and .619 +/- .009 kg/d in the two families. Selective genotyping was performed as a prescreening procedure to identify genomic regions potentially associated with ADG. A total of 75 genetic markers were used between both families. Markers identified as nominally significant (P < .05) in an individual marker analysis were subsequently typed in all individuals. Markers still nominally significant (P < .05) after analysis with the complete family were then reevaluated together with flanking markers in an interval mapping analysis. A single region on chromosome 3, flanked by markers Sw2429 and Sw251, for the second family had a logarithm of the odds score of 2.9, which is suggestive of linkage with a quantitative trait locus for ADG. Differences were .033 +/- .009 kg/d between individuals inheriting alternative paternal alleles for Sw251, which was the most significant marker.