Improved fertility of frozen-thawed porcine spermatozoa with 3,3-dimethylglutaric anhydride poly-L-lysine as a novel cryoprotectant.

In this study, we determined the efficacy of 3,3-dimethylglutaric anhydride poly-L-lysine (DMGA-PLL) as a cryoprotectant for porcine spermatozoa. Porcine spermatozoa were cryopreserved in a freezing extender containing 3% (v/v) glycerol and various concentrations of DMGA-PLL. At 12 h after thawing, the motility index of spermatozoa cryopreserved with 0.25% (v/v) DMGA-PLL (25.9) was significantly (P < 0.01) higher than that of spermatozoa cryopreserved with 0%, 0.125%, or 0.5% DMGA-PLL (10.0-16.3). In addition, the blastocyst formation rate of embryos derived from spermatozoa cryopreserved with 0.25% DMGA-PLL (22.8%) was significantly (P < 0.01) higher than that of embryos derived from spermatozoa cryopreserved with 0%, 0.125%, or 0.5% DMGA-PLL (7.9%-10.9%). The mean number of total piglets born to sows inseminated with spermatozoa cryopreserved without DMGA-PLL (9.0) was significantly (P < 0.05) lower than that of total piglets born to sows inseminated with spermatozoa stored at 17°C (13.8). However, when spermatozoa cryopreserved with 0.25% DMGA-PLL were used for artificial insemination, the mean number of total piglets (11.7) was not significantly different from that obtained following artificial insemination using spermatozoa stored at 17°C. The results showed the usefulness of DMGA-PLL as a cryoprotectant in the cryopreservation of porcine spermatozoa.

Cryopreservation of pig spermatozoa using carboxylated poly-L-lysine as cryoprotectant.

In this study, we cryopreserved pig spermatozoa using carboxylated poly-L-lysine (CPLL) as the cryoprotectant to determine its efficacy. Pig spermatozoa were placed in a freezing extender containing 3% (v/v) glycerol and different CPLL concentrations. The motility indices of the spermatozoa cryopreserved with 0.25% (v/v) CPLL at 6 (59.3), 9 (53.7), and 12 (26.2) h after thawing were significantly higher (P < 0.01 or P < 0.05) than those of the spermatozoa cryopreserved without CPLL (53.7, 40.1, and 17.5 at 6, 9, and 12 h after thawing, respectively). The concentration of CPLL in the freezing extender did not affect the ability of frozen-thawed spermatozoa to fertilize oocytes in vitro. However, the blastocyst formation rate of embryos derived from spermatozoa cryopreserved with 0.25% CPLL (24.6%) was significantly higher (P < 0.01) than that of embryos derived from spermatozoa cryopreserved without CPLL (11.2%). The conception rate of the sows inseminated with spermatozoa cryopreserved with 0.25% CPLL (72.2%) was not significantly different from that of the sows inseminated with spermatozoa stored at 17°C (81.3%). However, the mean number of total piglets born to the former (10.0) was significantly lower (P < 0.05) than that of total piglets born to the latter (13.4). The results showed that CPLL in the freezing extender maintained the motility of frozen-thawed pig spermatozoa and improved the in vitro development of embryos produced by in vitro fertilization. In addition, we have demonstrated that piglets could be obtained with artificial insemination using spermatozoa cryopreserved with CPLL.

Assessment of reproductive and growth performance of pigs on commercial swine farms in southern Kyushu, Japan.

The objective of the present study was to assess the productivity of pigs to investigate the time-dependent change in productivity and compare productivity according to breeding company group and porcine reproductive and respiratory syndrome (PRRS) status on commercial swine farms in southern Kyushu, Japan. Data used in the present study were 245 annual productivity records from 2014 to 2018 obtained from 72 farms. Average sow inventory was 481.2 sows. Mean numbers of pigs weaned per sow per year and market pigs sold per sow per year were 23.7 and 21.6, respectively. Pigs born alive per litter increased from 11.1 to 11.9 pigs from 2014 to 2018 (p < .05). Farms using domestic breeding companies had similar numbers in 2016 to those using international breeding companies, but fewer pigs in 2014, 2015, 2017, and 2018 (p < .05). Farms with an unknown or unstable PRRS status had fewer pigs born alive per litter and pigs weaned per sow per year than those with stable or negative PRRS statuses (11.2 ± 0.06 vs. 11.8 ± 0.08 pigs and 22.6 ± 0.38 vs. 25.0 ± 0.22 pigs, respectively; p < .05). These results can be used to establish feasible targets and standards of performance to identify problem areas and improve production.

Quantitative assessment of the effects of outside temperature on farrowing rate in gilts and sows by using a multivariate logistic regression model.

It is well known that pigs are sensitive to heat stress, but few studies have assessed the critical temperature that affects farrowing rate. Therefore, the objective of the present study was to assess the effects of outside temperature on farrowing rate by using a multivariate logistic regression model. Data were obtained from 25 commercial farms, including 26,128 service records for gilts and 120,655 service records for sows. Two variables, maximum temperature (MAX) and temperature humidity index (THI), were used as an indicator for climate conditions. In gilts, an interaction between climate conditions and service number was associated with farrowing rate (p < .05). In the first service, farrowing rate decreased as climate conditions increased, whereas no relationship was found in the second service or later. In sows, farrowing rate at first service decreased as MAX increased from 22°C or THI increased from 66 (p < .05), but no apparent reduction under heat conditions was found in the second service or later. Additionally, effect of heat stress on farrowing rate in parities 1-2 was higher than those in parities 3-5 and ≥6 (p < .05). These results can be applied to field conditions as a standard for the critical temperature for farrowing rate.

Assessment of reproductive performance in F1 sows exposed to the porcine epidemic diarrhea virus at different periods of production stage on farms with different hygienic environments.

Porcine epidemic diarrhea (PED) occurred in Japan in 2013 after an interval of 7 years. The present study assessed individual productivity of sows exposed to PED virus at different periods of the production stage. The present study was performed at three commercial farms that had PED outbreak during the month of December 2013. Herd immunization was conducted for all gilts and sows. The production records were obtained for sows that were alive during the PED outbreak at each farm. The sows were categorized into six groups based on the period in which they were exposed to PED virus between days 0-30 (G1), 31-60 (G2), 61-90 (G3), or after 91 days of pregnancy (G4), during lactation (L), and after weaning (W). The control group was assigned based on the records before the period of PED outbreak (uninfected group). The number of sow's records obtained from farms A, B, and C were 1056, 1137, and 1035, respectively. Compared with the uninfected group, there was no reduction in the number of pigs born alive in the G1-G4 groups. Sows of the G4 and L groups, however, had 4-9 pigs fewer pigs weaned, and a 36%-77% greater pre-weaning mortality than the uninfected group (P < 0.05). There was no difference in farrowing rate and number of pigs born alive at subsequent parities among the sow groups. There were no interactions between sow groups and parity for sow productivity.

Impact of porcine epidemic diarrhea on herd and individual Berkshire sow productivity.

Porcine epidemic diarrhea (PED) is an emerging disease of pigs in several countries. In the present study, individual sow productivity of Berkshire sows exposed to PED virus at different stages of production was compared. On a commercial farrow-to-finish farm in Kagoshima Prefecture, Japan, the clinical presence of PED was observed in the farrowing barn on January 6, 2014, and all gilts and sows were immunized on January 9, except those in the farrowing barn. The sows were categorized into six groups based on the period in which they were exposed to PED virus: between days 0-30 (G1), 31-60 (G2), 61-90 (G3), or after 91 days of pregnancy (G4), during lactation (L), and after weaning (W). The control group was not exposed to PED during the period of PED outbreak. The study was based on 574 production records. The sows of the G4 and L groups had the fewest piglets weaned (4.8±0.4, and 4.0±0.3 pigs, respectively; P<0.05) and the greatest pre-weaning mortality (33.1±4.8%, and 39.7±4.1%, respectively; P<0.05). The number of piglets weaned and pre-weaning mortality, however, did not differ among the G1, G2, G3, and uninfected groups. The G4 and W groups had slightly lesser farrowing rates than the uninfected group (P<0.05), however, similar subsequent piglet litter performance as the uninfected group. In conclusion, the effect of PED on individual sow productivity differed with the production stage in which sows were exposed to PED virus.

The effect of porcine epidemic diarrhea (PED) on ovarian function and reproductive performance after weaning in Berkshire sows.

The purpose of this study was to investigate the ovarian condition at weaning and subsequent reproductive performance of Berkshire sows following an outbreak of PED. This study was conducted on a farrow-to-finish farm that experienced a PED outbreak beginning on January 6, 2014. Blood samples were collected at weaning from 19 to 20 sows every month from July 2013 until July 2014 to investigate the ovarian condition. The mean progesterone concentration was numerically higher during January 2014 than the other months, but this difference was not significant. The mean estradiol-17ß concentration was higher during January 2014 than during July and October 2013 (P < 0.05). In addition, reproductive performance was compared during January, February, and March before (2013) and after (2014) the PED outbreak. Sows that farrowed in January had higher preweaning mortality in 2014 than in 2013 (P < 0.05), but sows that farrowed in February and March had similar preweaning mortality in 2013 and 2014 (P > 0.10). Sows that farrowed between January and March 2014 had 15% lower farrowing rate than those that farrowed during the same months in 2013 (P < 0.05). In conclusion, our results demonstrate poorer reproductive performance of Berkshire sows after a PED outbreak compared with before the outbreak.