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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic and Genomic Approaches to Improve Swine Reproductive Efficiency

Location: Reproduction Research

Title: Genome wide association of changes in feeding behavior due to heat stress in pigs)

Author
item Cross, Amanda
item Keel, Brittney
item Brown Brandl, Tami
item Rohrer, Gary

Submitted to: International Society for Animal Genetics (ISAG)
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Heat stress negatively impacts pork production. Grow-finish production losses include decreased growth, reduced feed intake, and mortality. Pigs change their feeding behavior to decrease heat production when temperatures are elevated. Identification of pigs that are more tolerant of warmer temperatures would enable determination of genetic markers and candidate genes that are associated with thermal tolerance. Therefore, the objective of this study was to identify genetic markers associated with changes in feeding behavior due to heat stress. Data were collected on grow-finish pigs (n = 1345) from July 2011 to March 2016. Barrows and gilts were in grow-finish groups (n = 240), distributed into six pens with 40 pigs per pen. Pigs were from Landrace or Yorkshire sire lines. Animals were tagged with an electronic identification tag upon entry into the barn fitted with a feed system that monitored feeding behavior. Temperature and relative humidity were obtained and temperature humidity indices (THI) calculated. THIs were divided into groups, where less than 23.33 °C was considered “normal”, between 23.33 °C and 26.11 °C considered an “alert”, between 26.11 °C and 28.88 °C considered a “danger”, and greater than 28.88 °C considered an “emergency”. Standardized differences between a pig’s feeder activity and the average feeder visit activity for an animal of that sex, breed of sire and THI category were calculated. DNA was extracted and genotyping conducted using Illumina BeadChip products, all animals (n = 853) were imputed to the NeoGen Porcine GGPHD chip. A genome-wide association study (GWAS) for an animal’s change in feeding behavior between different THI categories was conducted using Bayesian analyses in GenSel. Candidate genes were identified using a 200-kb region around significant single nucleotide polymorphisms (SNP). Heritabilities for difference of a pig’s ranking between each of the THI categories from GenSel were moderate to high (0.146 to 0.478). Greater than 71 % of genetic variation was explained by regions within eight chromosomes when comparing feeder visit activity differences between danger and emergency THI. Gene ontology (GO) enrichment analysis showed that biological processes related to sensory perception and detection of chemical stimuli over-represented in genes in the identified regions. These genetic markers may facilitate genetic selection for improved grow-finish performance during elevated ambient temperatures.

Last Modified: 04/22/2017
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