We have reported that artificial insemination (AI) with frozen-thawed boar semen supplemented with caffeine increased the number of uterine sperm by inhibiting the migration of polymorphonuclear leukocytes (PMNs) into the uterine lumen, resulting in improvement of the fertility of gilts and sows. Our aim of the present study was to examine the effects of the addition of caffeine to the Modena solution on fertility of sows in the commercial pig farm after AI with liquid-stored semen during hot season. Semen was collected from boars in the commercial pig farm once a month. Percentage of morphologically abnormal sperm in cool season (November-May) and hot season (June-October) were 20.4% and 38.4%, respectively. Sows were cervically inseminated with 100ml liquid-preserved boar semen (Control group, n＝23 in cool season, n＝23 in hot season), with 50ml Modena solution (Modena group, n＝32 in cool season, n＝25 in hot season), or with 50ml Modena solution supplemented with 30mM caffeine (Caffeine group, n＝28 in cool season, n＝27 in hot season). Farrowing rates of sows inseminated during hot season in Control and Modena groups were lower than those inseminated during cool season (P<0.05). There was no difference in the farrowing rate between seasons in Caffeine group. The results demonstrated that the addition of caffeine to the semen extender could suppress lowering of farrowing rate after AI with liquid-stored semen during hot season in commercial pig farm.

The objective of this research was to evaluate the effect of an astaxanthin-supplemented commercial swine diet upon semen production and sperm quality during the summer season (June-August). Dietary treatments were a non-supplemented basal diet (n＝3) or the basal diet supplemented with 50-100 g astaxanthin (n＝4). Collected semen was diluted with Modena solution and stored at 15°C. Two months of dietary astaxanthin had no effect on ejaculate volume and sperm concentration, total sperm numbers, and sperm abnormalities or motility prior to storage (P>0.05). After 1, 3, and 5 days of storage, sperm motility was equivalent between dietary treatments. However, sperm motility (after 5 h of incubation) after 7 days of storage was significantly higher (P<0.05) in the astaxanthin compared with basal diet group.

In conclusion, we demonstrated that an astaxanthin-supplemented commercial swine diet administered during the summer season improved boar sperm quality after liquid storage at 15°C for 7 days.

In a large-scale survey regarding 46,724 Berkshire pig carcasses and 342,787 other pig carcasses conducted at two slaughterhouses in Kagoshima prefecture, the percentage of top-grade Berkshire pig carcasses (52%) was lower than that of other pig carcasses (60%) because of excessive backfat thickness (Berkshire pig, 28%;other pig, 13%). In the first experiment, the effect of sex (barrow and gilt) on the backfat thickness of Kagoshima Berkshire pigs raised under restricted feeding conditions was investigated. The backfat thickness of barrow carcasses was thicker than that of gilt carcasses. In the second experiment, the effects of the feeding method and sex on carcass evaluation were investigated to establish a management method of controlling the backfat thickness of Kagoshima Berkshire pigs in the late fattening stage on pig farms. Ninety pigs were assigned to three dietary treatment groups:intermittent feeding on a 76% total digestible nutrients (TDN76%) diet (I-T76) from 80 kg of body weight, restricted feeding on a TDN76% diet (R-T76) from 70kg of body weight, and restricted feeding on a TDN70% diet (R-T70) from 70kg of body weight. Each dietary treatment group consisted of three subgroups:barrow (n＝10), gilt (n＝10), and mixed (barrow, n＝5 and gilt, n＝5). In the barrow subgroups, the percentages of lower-grade carcasses due to excessive backfat thickness in the I-T76, R-T76, and R-T70 groups were 80%, 76%, and 50%, respectively. On the other hand, in the mixed subgroups, the percentages of lower-grade carcasses in the I-T76, R-T76, and R-T70 groups were 20%, 10%, and 10%, respectively. In the barrow subgroups, the percentages of top-grade carcasses in the I-T76, R-T76, and R-T70 groups were 20%, 33%, and 50%, respectively. On the other hand, in the mixed subgroups, the percentages of top-grade carcasses in the I-T76, R-T76, and R-T70 groups were 80%, 80%, and 70%, respectively. In all dietary treatment groups, the backfat thickness in the barrow subgroups were significantly thicker than those in the gilt subgroups. In the mixed subgroups, however, there were no differences in the backfat thickness between barrow and gilt. These results suggested that the mixed rearing of barrow and gilt, switching feed as early, and lowering TDN content of the feed for the late fattening stag are effective management methods raising the percentage of top-grade carcass of Kagoshima Berkshires pigs by suppressing excessive backfat thickness.