A Study of Cattle Disposition: Exploring QTL Associated with Temperament

In any production setting, cattle disposition (temperament) has a great impact on handling and performance. Thus, behavior can be economically important, yielding the rationale for study. Wegenhoft (2005) previously identified several quantitative trait loci (QTL) for disposition, including a partially paternally imprinted QTL at 0cM on bovine chromosome (BTA) 8 that overlaps a region on human chromosome 8 associated with Schizophrenia in humans. The objective of this study was to identify a candidate gene influencing behavior in this region. Two genes from the human Schizophrenia region, bone morphogenetic protein 1 (BMP1) and bridging integrator 3 (BIN3), were initially chosen because they were reported to be imprinted in humans and mice, and were expected to map to BTA8. Two other genes, cathepsin B (CTSB) and farnesyl-diphosphate-farnesyltransferase 1 (FDFT1), were chosen as they mapped closer to the predicted QTL location and reported functions suggested a role for these in behavior. Amplicons from each of these 4 genes were sequenced, using genomic DNA from Texas A&M Angleton resource herd animals, to find single nucleotide polymorphisms (SNP). There were no SNP within the amplicon for BMP1, but 3 were found in BIN3, 7 in CTSB and 4 in FDFT1. Complementary DNA was synthesized from total RNA from muscle and liver samples collected at slaughter, and was sequenced to analyze SNP in transcribed regions to investigate the imprinting status of BIN3, CTSB and FDFT1. There was no evidence of imprinting of these genes. Microsatellites within each gene were amplified to genotype the entire population. Genotypes from the Angleton herd were used to update linkage maps for BTA8 and 11. Genotypes from the Texas A&M McGregor Genomics Project herd were used with 133 other markers to construct linkage maps for each of the 29 autosomes in this population. There were QTL for various component traits of behavior (aggressiveness, nervousness, flightiness, gregariousness, and overall disposition) measured at 4 different times (weaning, feeding, slaughter or time of first calving) on BTA3, 6, 12, 16, 26 and 29 under a Mendelian model, and on BTA3, 6, 11, 12, 13, 19, 22 and 29 under a parent-of-origin model