Takuro Oikawa

Genetic relationship of body measurement traits at early age with carcass traits in Japanese black cattle

Estimates of genetic parameters were obtained for body measurement traits of 648 animals at 4 months of age, of 545 at 8 months and carcass traits of 14 972 animals with the use of an animal model by the restricted maximum likelihood procedure. The estimated heritabilities for carcass traits were high (0.41 to 0.54). At 4 months the estimated direct heritabilities for body measurement traits were moderate to high (0.28 to 0.64), except for chest width (0.19); at 8 months they were also moderate to high (0.23 to 0.49), except for chest depth and chest width (0.18 and 0.06, respectively). Maternal heritabilities for all body measurement traits were low at both ages. The results indicate that because of their moderate direct genetic correlations with body measurement traits, carcass weight, rib thickness and subcutaneous fat thickness can be improved; however, rib eye area and beef marbling standard show little such possibility considering their correlation with body measurement traits.

Genetic variability of maternal effect on body measurements and its intra- and inter-genetic relationship with direct effect in Japanese Black calves

This study was conducted to evaluate the importance of maternal effect on body measurement traits at an early stage of growth, and to estimate the genetic relationships between direct and maternal effects and among body measurement traits at 0u2003month (0-mo) and 4u2003months (4-mo) of age in a population of Japanese Black calves. Body measurements and body weight of 889 Japanese Black calves were estimated with the use of an animal model by the Residual Maximum Likelihood procedure. Direct heritabilities were low to moderate, ranging between 0.17u2003±u20030.09 and 0.48u2003±u20030.13 at 0-mo, and slightly lower, ranging between 0.15u2003±u20030.07 and 0.33u2003±u20030.13 at 4-mo. Estimated maternal heritabilities were low to moderate, ranging between 0.08u2003±u20030.07 and 0.33u2003±u20030.07 at 0-mo and 0.13u2003±u20030.06 to 0.33u2003±u20030.06 at 4-mo. The direct genetic correlations between 0-mo and 4-mo were moderate to highly positive, ranging from 0.53u2003±u20030.23 to 0.96u2003±u20030.09. The estimated direct genetic correlation of chest width with other width traits was low and positive at both ages, whereas with hip width it was high and positive (0.80u2003±u20030.09) at 0-mo, suggesting that simultaneous improvement of body width of the front and back parts is possible. Maternal genetic effects were relatively independent of direct genetic effects for body measurement traits and can be considered in genetic evaluation.

Maternal lineage of Okinawa indigenous Agu pig inferred from mitochondrial DNA control region

Objective The Agu is the only native pig breed in Japan, which is reared in Okinawa prefecture, the southernmost region in Japan. Its origins are considered to be of Asian lineage; however, the genetic background of the Agu is still unclear. The objective of this study was to elucidate the maternal lineage of the Okinawa indigenous Agu pig with the use of the mitochondrial DNA (mtDNA) control region. Methods The mtDNA control regions of Agu pigs were sequenced and the phylogenetic relationship among Agu, East Asian and European pigs was investigated with the use of 78 Agu individuals. Results Twenty-seven polymorphic sites and five different haplotypes (type 1 to type 5) were identified within the Agu population. Phylogenetic analysis indicated that types 1 and 2 were included in East Asian lineages; however, the remaining types 3, 4, and 5 were of European lineages, which showed a gene flow from European pigs in the 20th century. Sixty-seven out of 78 Agu individuals (85.9%) possessed mtDNA haplotypes 1 and 2 of the East Asian lineage, which were identical to two haplotypes of ancient mtDNA (7,200 to 1,700 years before the present) excavated at archaeological sites in Okinawa. Conclusion This study confirmed that the East Asian lineage is dominant in the maternal genetic background of the Agu population, supporting the hypothesis that the ancestors of the Agu pig were introduced from the Asian continent.

Effect of heat stress on age at first calving of Japanese Black cows in Okinawa.

Calving records from birth certificates of cows were analyzed to investigate the effect of heat stress on age at first calving (AFC) of Japanese Black cows. The data set covered 20u2009years (1990-2009) of calving records. Total number of records was 9279. Daily weather information from weather stations in the vicinity of the farms was used. Temperature-humidity index (THI) fitted to a linear model covered 30u2009days pre-insemination to 61u2009days post-insemination. Statistical analysis was conducted with procedures of SAS/STAT. Preliminary analysis showed that THI of the lowest temperature and humidity was most conducive to AFC. Covariance analysis, including main effect of sire, farm and year of insemination and covariates of THI on days showed that regression coefficients of THI on day -7, day -2 and day +31 were statistically significant. The estimated piecewise regression line showed different responses of AFC to THI on days: roof-shasped downward trend on day -7, hockey-stick shaped upward trend on day -2 and day +31. The difference among the estimated regression lines may be caused by direct and indirect factors on reproduction: indirect effect of reduced feed intake, failure of conception at previous insemination, direct effect of heat stress on oocyte and embryo development.