The VFA emission in a pig house influences sense of smell with a very small amount. The VFA reduction in a pig house is important for the malodor measures of the piggery. In this study the selection of the microbe that has ability for superior VFA reduction was considered from 515 Bacillus libraries, and its VFA reduction microbe which mixed with feed was given to a pig. Microbes that were inoculated into VFA addition nutrient medium, were judged by ability for increase, and some microbes were selected at first. As for the primary selection microbes, were measured VFA reduction ability. The microbe Bacillus thuringiensis D45 indicating the most excellent VFA reduction was selected at last. The D45 that was inoculated into pig feces suspension, and cultured under an aerobic condition, reduced VFA. The D45 does not influence health and dissection views and does not infiltrate the internal organs even if it was given to a piglet. The D45 was not detected in rectal feces 1 week later of the mixture stop. The D45 given to a growing-finishing pig reduced VFA without having an influence on feeding and the DG. The D45 that was mixed 10⁵ CFU/g with feed，and was given to a growing-finishing pig reduced VFA about 60%. Increase in number of D45 to 10⁶ CFU/g did not contribute to the improvement of the VFA reduction effect. The D45 of 10³ CFU/g did not reduce VFA. These results suggested that the most suitable number of D45 is 10⁵ CFU/g.

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The objectives of the present study were to characterize farrowing space (FS) utilization efficiency on commercial farms and to examine the relationships between FS utilization efficiency measurements and those possible factors. A questionnaire survey was undertaken to obtain information on FS utilization from 115 breeding farms. The FS data of the 94 farms (81.7%) that returned the questionnaires were coordinated with the respective reproductive performance data. The 94 farms were categorized into two groups on the basis of the upper 25^th percentile of number of pigs weaned per FS per year: high-performing farms and ordinary farms based on the FS utilization efficiency. In addition to herd reproductive performance data, a set of time-series data in 13 four-week periods during a year was created for each farm to obtain mean and its coefficient of variation (CV, %) as a measurement of within-farm variability for number of females served per 4-week. Correlation analysis and regression analysis were applied to the data. Means (±SEM) of pigs weaned per FS per year, litters farrowed per FS per year and the CV of the total number of females served per 4-week in a year were 97.33±2.70 pigs, 9.86±1.28 litters and 12.82±0.79%, respectively. High-performing farms had 42.91 more pigs weaned per FS per year, 3.89 more litters farrowed per FS per year and 4.83% lower CV for the number of females served than ordinary farms (P<0.05). In modelling, a higher number of pigs weaned per FS per year was associated with annual farrowing rate and a lower CV% for the number of females served 16 weeks previously (P<0.01). In conclusion, a higher FS utilization efficiency appeared to be related to mating management on female pigs.

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Effects of number and polymorphic content of DNA markers on marker homozygosity were examined by bootstrap simulation using genotype dataset of a simple F₂ family. The deviation of marker homozygosity in this population is unchanged as increased number of the replication. The increased sampling number of the markers was made more small deviation of marker homozygosity of individuals. When 70 markers were sampled from markers with 2 alleles, the coefficient of correlation with marker homozygosity calculated from all markers was over 0.7. In contrast, it is 40 markers in sampling from markers with more than 3 alleles over same criteria. Similarly, for full-informative markers we were able to evaluate certain marker homozygosity when the number of markers was greater than 20. From these results, it was shown that 70 markers with 2 alleles and/or 20 markers with highly polymorphism are required for evaluating marker homozygosity of the individual level.

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