Agricultural Contracting

The information in this presentation was assimilated during a University of Missouri Outreach & Extension Professional Implementation Experience (Train the Trainer) program held on April 4 and 5, 2000. The information assimilated herein was provided by the individual speakers. Please feel free to use this information for educational and informative uses

Sexually Dimorphic Transcriptomic Changes of Developing Fetal Brain Reveal Signaling Pathways and Marker Genes of Brain Cells in Domestic Pigs

In this study, transcriptomic changes of the developing brain of pig fetuses of both sexes were investigated on gestation days (GD) 45, 60 and 90. Pig fetal brain grows rapidly around GD60. Consequently, gene expression of the fetal brain was distinctly different on GD90 compared to that of GD45 and GD60. In addition, varying numbers of differentially expressed genes (DEGs) were identified in the male brain compared to the female brain during development. The sex of adjacent fetuses also influenced gene expression of the fetal brain. Extensive changes in gene expression at the exon-level were observed during brain development. Pathway enrichment analysis showed that the ionotropic glutamate receptor pathway and p53 pathway were enriched in the female brain, whereas specific receptor-mediated signaling pathways were enriched in the male brain. Marker genes of neurons and astrocytes were significantly differentially expressed between male and female brains during development. Furthermore, comparative analysis of gene expression patterns between fetal brain and placenta suggested that genes related to ion transportation may play a key role in the regulation of the brain-placental axis in pig. Collectively, the study suggests potential application of pig models to better understand influence of fetal sex on brain development

Analysis of polygenic selection in purebred and crossbred pig genomes using generation proxy selection mapping

Abstract Background Artificial selection on quantitative traits using breeding values and selection indices in commercial livestock breeding populations causes changes in allele frequency over time at hundreds or thousands of causal loci and the surrounding genomic regions. In population genetics, this type of selection is called polygenic selection. Researchers and managers of pig breeding programs are motivated to understand the genetic basis of phenotypic diversity across genetic lines, breeds, and populations using selection mapping analyses. Here, we applied generation proxy selection mapping (GPSM), a genome-wide association analysis of single nucleotide polymorphism (SNP) genotypes (38,294–46,458 markers) of birth date, in four pig populations (15,457, 15,772, 16,595 and 8447 pigs per population) to identify loci responding to artificial selection over a period of five to ten years. Gene-drop simulation analyses were conducted to provide context for the GPSM results. Selected loci within and across each population of pigs were compared in the context of swine breeding objectives. Results The GPSM identified 49 to 854 loci as under selection (Q-values less than 0.10) across 15 subsets of pigs based on combinations of populations. The number of significant associations increased when data were pooled across populations. In addition, several significant associations were identified in more than one population. These results indicate concurrent selection objectives, similar genetic architectures, and shared causal variants responding to selection across these pig populations. Negligible error rates (less than or equal to 0.02%) of false-positive associations were found when testing GPSM on gene-drop simulated genotypes, suggesting that GPSM distinguishes selection from random genetic drift in actual pig populations. Conclusions This work confirms the efficacy and the negligible error rates of the GPSM method in detecting selected loci in commercial pig populations. Our results suggest shared selection objectives and genetic architectures across swine populations. The identified polygenic selection highlights loci that are important to swine production

Evaluating the Effects of In Utero Heat Stress on Piglet Physiology and Behavior Following Weaning and Transport

The study objective was to determine whether in utero heat stress (IUHS) affects piglet physiology and behavior following common production practices. A total of 12 gilts were confirmed pregnant and allocated to either heat stress (HS; n = 6) or thermoneutral (TN; n = 6) conditions on day 30–60 of gestation. At weaning (22.5 ± 2.3 days of age), 1 boar and 1 barrow of median weight were selected from each litter and transported for approximately 7 h. Piglets were then blocked into pens (n = 2/pen) by in utero treatment (IUHS (n = 12) or in utero thermoneutral (IUTN, n = 12)) and sexual status (boar (n = 6/in utero treatment) or barrow (n = 6/in utero treatment)). Plasma cortisol, non-esterified fatty acids (NEFA), insulin and glucose were evaluated 1 day prior to transport (pre-transport) and immediately after transport (post-transport). Behavioral data were collected on day 1–7 for 60 min at four different time points each day. In utero heat stressed piglets exhibited reduced cortisol concentrations compared to IUTN piglets immediately post-transport (p = 0.04). Glucose concentrations were not affected by in utero treatment. Insulin concentrations were reduced in IUTN piglets post-transport compared to pre-transport (p = 0.002), but no differences were detected for IUHS pigs. Non-esterified fatty acids tended to be reduced overall for IUHS vs. IUTN pigs (p = 0.08). Overall, IUHS piglets performed more drinking behaviors (p = 0.02) and tended to perform more aggressive behaviors (p = 0.07) than IUTN piglets in the 7 days post-transport. In summary, there was some evidence for altered physiological and behavioral responses among IUHS piglets compared to IUTN piglets following weaning and transport

Additional file 1 of Analysis of polygenic selection in purebred and crossbred pig genomes using generation proxy selection mapping

Additional file 1: Table S1: Proportion of variation in AGE explained by SNPs for each purebred subset using five replications of randomly simulated genotype data

Additional file 3 of Analysis of polygenic selection in purebred and crossbred pig genomes using generation proxy selection mapping

Additional file 3: Table S3: Population, chromosome, SNP effect, Q-value, gene identifier, associated human traits, and associated pig traits for SNPs associated with AGE from GPSM analyses

Additional file 2 of Analysis of polygenic selection in purebred and crossbred pig genomes using generation proxy selection mapping

Additional file 2: Table S2: Number of SNPs significantly associated with AGE for each subset using five replicates of randomly simulated genotype data

Gestational heat stress alters postnatal offspring body composition indices and metabolic parameters in pigs.

The study objectives were to test the hypothesis that heat stress (HS) during gestational development alters postnatal growth, body composition, and biological response to HS conditions in pigs. To investigate this, 14 first parity crossbred gilts were exposed to one of four environmental treatments (TNTN, TNHS, HSTN, or HSHS) during gestation. TNTN and HSHS dams were exposed to thermal neutral (TN, cyclical 18-22°C) or HS conditions (cyclical 28-34°C) during the entire gestation, respectively. Dams assigned to HSTN and TNHS treatments were heat-stressed for the first or second half of gestation, respectively. Postnatal offspring were exposed to one of two thermal environments for an acute (24 h) or chronic (five weeks) duration in either constant TN (21°C) or HS (35°C) environment. Exposure to chronic HS during their growth phase resulted in decreased longissimus dorsi cross-sectional area (LDA) in offspring from HSHS and HSTN treated dams whereas LDA was larger in offspring from dams in TNTN and TNHS conditions. Irrespective of HS during prepubertal postnatal growth, pigs from dams that experienced HS during the first half of gestation (HSHS and HSTN) had increased (13.9%) subcutaneous fat thickness compared to pigs from dams exposed to TN conditions during the first half of gestation. This metabolic repartitioning towards increased fat deposition in pigs from dams heat-stressed during the first half of gestation was accompanied by elevated blood insulin concentrations (33%; P = 0.01). Together, these results demonstrate HS during the first half of gestation altered metabolic and body composition parameters during future development and in biological responses to a subsequent HS challenge

Effect of gestational and acute postnatal HS on blood gas variables and metabolites.

1<p>iCa, ionized calcium.</p>2<p>PCV, packed cell volume.</p>3<p>GestTrt, gestational treatment.</p>4<p>PostTrt, postnatal treatment.</p>5<p>G x A, interaction between gestational and postnatal treatment groups.</p><p>Different letters indicate GestTrt comparisons P<0.05.</p>#<p>indicates PostTrt comparisons P<0.05.</p><p>Effect of gestational and acute postnatal HS on blood gas variables and metabolites.</p

Acute postnatal heat stress (HS) alters temperature indices and feed intake over the 24 h treatment period.

<p>A) Rectal temperature increased during postnatal HS (<i>P<</i>0.001) and a postnatal treatment by time interaction was also detected (<i>P<</i>0.001). B) Respiration rate presented as breaths per minute (bpm) was elevated as a result of postnatal HS (<i>P<</i>0.001) in addition to the detection of a postnatal treatment by time interaction (<i>P<</i>0.01). C) Skin temperature was increased in pigs subject to postnatal HS compared to thermal neutral <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110859#pone.0110859-Early1" target="_blank">[30]</a> counterparts (<i>P<</i>0.001) in addition to detection of a postnatal treatment by time interaction (<i>P<</i>0.001). A gestational by postnatal treatment interaction was observed in skin temperature (<i>P</i> = 0.05) whereby gestational treatments exposed to HS during the second half of gestation had higher skin temperature (0.5°C) under HS conditions but lower skin temperature under TN conditions (0.3°C) compared to HSTN and TNTN gestational treatments. D) Cumulative feed intake was reduced (<i>P</i><0.01) in HS pigs compared to their TN counterparts. TN pigs gained weight while HS pigs lost weight over the acute HS period. No gestational effect was observed for feed intake or weight gain parameters (<i>P></i>0.1). E) The difference between rectal and skin temperatures is elevated in pigs from TNHS and HSHS vs. TNTN and HSTN treatments at 16 h (<i>P = </i>0.1) and 20 h (<i>P = </i>0.01) of HS. ^#<i>P</i><0.1; *<i>P</i><0.05. Data shown represent the LS-mean ± SEM of n = 6 pigs per postnatal treatment per gestational treatment.</p