定时输精对经产母猪繁殖性能及生殖激素的影响

试验旨在建立高效的经产母猪定时输精（timed artificial insemination，TAI）技术，研究了定时输精对经产母猪繁殖性能、断奶-分娩间隔、不同胎次母猪产仔性能及断奶后7 d内血清生殖激素水平的影响。选取309头2~8胎次二元（长×大）经产母猪，随机分为对照组和试验组，对照组母猪进行常规人工授精（artificial insemination，AI），试验组母猪进行断奶后24 h注射PMSG 1 000 IU，间隔72 h注射GnRH 100 μg，在注射GnRH后24和40 h各输精1次的定时输精技术。通过统计两组母猪的断奶1周内发情率、受胎率、分娩率、窝均产仔数等，判断定时输精对经产母猪繁殖性能的影响；通过对断奶时间和分娩时间的统计，检测定时输精对经产母猪断奶-分娩间隔的影响；用放射免疫（RIA）方法检测2~4胎次母猪断奶1周内血清E₂、LH、FSH和P₄的含量，研究定时输精对母猪生殖激素的影响。结果显示，试验组母猪发情率显著高于对照组（P<0.05），但两组间受胎率、分娩率差异不显著（P>0.05），窝均产仔数、窝均合格仔数和繁殖效率有增加的趋势，但差异不显著（P>0.05）；定时输精显著缩短了母猪的断奶-分娩间隔（P<0.05）。在胎次方面，3~4胎母猪使用定时输精的效果较好，其发情率、受胎率和分娩率均显著高于对照组（P<0.05）。在生殖激素方面，试验组E₂水平在注射PMSG后迅速上升，且在定时输精处理后66~96 h内持续高于对照组（P<0.05），试验组P₄水平在断奶后至配种前显著低于对照组（P<0.05），但配种后快速升高，并高于对照组；LH和FSH的含量在两组间无显著差异。综上，定时输精可有效提高经产母猪的断奶发情率，并减少其非生产天数，可显著提高3~4胎母猪的繁殖性能。

Effects of Timed Artificial Insemination on Reproductive Performance and Reproductive Hormone in Multiparous Sows

The purpose of this study was to establish an efficient timed artificial insemination (TAI) technology for multiparous sows. The experiment studied the effects of timed insemination on the reproductive performance of multiparous sows, the interval between weaning and farrowing, the farrowing performance of sows with different parities and the serum reproductive hormone levels within 7 days after weaning. A total of 309 binary (Landrace×Large White) sows of 2-8 parity randomly divided into control group and test group. The sows of control group were subjected to conventional artificial insemination (AI), and the sows of test group were given TAI by PMSG (1 000 IU) treatment for 24 h after weaning and GnRH (100 μg) treatment at 72 h interval, then followed by inseminations at 24 and 40 h after GnRH injection. The effects of timing insemination on reproductive performance of multiparous sows were evaluated by counting estrus rate in one week after weaning, conception rate, delivery rate and litter size. The effect of regular insemination on weaning delivery interval of multiparous sows was detected through the statistics of weaning time and delivery time. The radioimmunoassay (RIA) method was used to detect the serum E₂, LH, FSH and P₄ levels of sows with 2 to 4 parities within one week of weaning to study the effect of timed insemination on the reproductive hormones of sows. The results showed that the estrus rate of sows in the test group was significantly higher than that in the control group (P<0.05), but the conception rate and delivery rate were not significantly different between the two groups (P>0.05). Litter size per litter, qualified litter size per litter and reproductive efficiency increased, but the difference was not significant (P>0.05). Timed insemination significantly shortened the interval between weaning and farrowing (P<0.05). The estrus rate, conception rate and delivery rate of 3-4 litter sows were significantly higher than those of the control group (P<0.05). In terms of reproductive hormone, the E₂ level of the test group rose rapidly after PMSG injection, and was continuously higher than that of the control group (P<0.05) within 66 to 96 h after the timed insemination treatment. The level of P₄ in the experimental group was significantly lower than that in the control group from weaning to mating (P<0.05), but increased rapidly after mating, and higher than the control group. There was no significant difference in the content of LH and FSH between the two groups. In summary, timed insemination could effectively increase the rate of weaning and estrus of multiparous sows, reduce the number of non-productive days, and could significantly improve the reproductive performance of sows with 3 to 4 litters.