Okinawa Agu pigs are only raised in the Okinawa prefecture and are characterized by low growth performance and high-quality meat. This breed is often utilized as terminal boars for commercial pork production. The objective of this study was to investigate the growth pattern of Agu boars to inform their management. Five nonlinear growth models (Logistic, Gompertz, von Bertalanffy, Richards, and Janoschek) were used to describe the growth pattern of this breed. Animals were allowed ad libitum access to feed to 16 weeks of age and then reared under restricted feeding of 1.5kg/day to 34 weeks of age. From birth to 34 weeks, body weight (BW) data of 14 Agu pigs were collected weekly. A comparison among the five models revealed that the Richards model was the best fit to the growth data based on the adjusted R-square and Akaike’s information criterion. In the leave-one-out cross-validation, the Richards model was also superior in predicting the accuracy. According to the Richards function, Agu boars reached the inflection point of the maximum growth rate at 11.6 weeks at a BW of 29.6kg. The maximum growth rate of Agu boars was 496.9g/day.

In recent decades, the prolificacy potential of sows was dramatically developed by genetic improvements, and cross-fostering (CF) practices are implemented to sows farrowed piglets more than their functional teat number. The objective of this study was to investigate the effect of CF on subsequent performance at weaning and post weaning. The present study was conducted on a commercial farm reared hyper-prolific sows. Data used in this study was 2,292 farrowing records in 1,337 sows that farrowed from March 2016 to February 2017. Sows were classified to three groups based on CF practices: non-CF sows, CF－ sows that defined as sows provided their piglets to other sows, and CF+ sows that defined as sows received piglets from other sows. Linear mixed-effect model was used to analyze the relationship between CF and productivity, including parity and number of piglets at beginning of lactation in the model. Of 2,292 records, 1,366 were practiced CF (59.6%), and proportion of CF－ and CF+ sows were 28.5% and 31.1%, respectively. CF was associated with number of piglets weaned and preweaning piglet mortality only in the number of piglets at beginning of lactation 13-14 pigs group: CF－ and non-CF sows had 1.2-1.7% higher preweaning piglet mortality and 0.3-0.4 lower number of piglets weaned (P<0.05). CF－ sows had 0.2kg lower piglet weight at weaning than non-CF and CF+ sows (P<0.05). CF was not associated with weaning to first mating interval and farrowing rate at first service, but CF－ sows had the highest number of piglets born alive at subsequent parity and CF+ sows had the lowest (P<0.05). In conclusion, there was no apparent reduction of productivity between non-CF sows and CF practices sows.

We used the microvolume air cooling (MVAC) method to optimize sugar additives for vitrification media, in order to improve the survivability of vitrified porcine blastocysts. We also examined the effectiveness of vitrification devices by comparing a hand-made device with a commercially available device (Hi-Stick). Blastocysts were collected from gilts, then vitrified in either a sucrose-added vitrification media using a hand-made device (HDM-S), or in a trehalose-added vitrification media using a hand-made device (HDM-T) or a Hi-Stick (HST-T). Survival of the vitrified embryos was assessed using in vitro cultures, and by embryo transfer to recipient gilts. Untreated embryos (fresh embryos) were used as the control. The rate of hatched blastocysts in vitro was 73.1% for HDM-S, 76.9% for HDM-T, 88.0% for HST-T, and 92.0% for the control group. No significant difference was observed between each group. The piglet production rate in of the embryo transfer test, was 13.3% for HDM-S, 26.5% for HDM-T, 32.3% for HST-T, and 42.4% for the control group. The piglet production rate was calculated as follows: total number of delivered piglets / total number of transferred embryos. No significant difference was observed between HST-T and the control group, however, the HDM-S performed significantly worse in the piglet production rate than the other groups. The HDM-T showed a significantly lower production rate than the control group. These results indicate that the piglet production rate can be optimized when using the MVAC method for porcine blastocysts vitrified in trehalose-added media by using a Hi-Stick, because the resultant piglet production rate is similar to that of fresh embryos.