| Meishan pig is belong to Taihu pig,a celebrated pig breed in China,famous for its high fertility characteristics.The effective conservation of Meishan pigs not only can effectively preserve their excellent traits,but also provide valuable germplasm resources,improving the reproductive performance of the introduced pig breeds and breeding of new breeds(supporting lines).This study analyzed the breeding records of pure breeding and hybrid utilization of Meishan pigs(medium-sized)of Kunshan Meishan Pig Breeding Co.,Ltd.from 2015 to 2019 to analyze the conservation effect and hybrid utilization.Meanwhile,this study has examined the reproductive hormones level around ovulation period,aim to provide a certain basis for the high-yielding mechanism of Meishan pigs,and to provide a reference basis for the hormone levels for Meishan pigs to determine the best breeding timing.The main results were as follows:1.The reproduction record of Meishan pigs(medium-sized)of Kunshan Meishan Pig Breeding Co.,Ltd.from 2015 to 2019 were analyzed in our study,total 725 litters.We found that the total number born(TNB)and number born alive(NBA)were mostly concentrated in 14-16,accounting for 45.52%and 45.93%,followed by 11-13,17-19.There was no significant difference in the TNB and NBA of the primiparous sows between 2015 and 2019;however,the TNB and NBA of the multiparity sows(?3 parities)in 2019 is significantly higher than other years(P<0.05),showed a gradual upward trend.These data indicated that Meishan pigs generally maintained the excellent characteristics of high reproductive performance during the breeding process from 2015 to 2019.2.In this study,we separately counted the differences between pure breeds and hybrids in different parities and parities,and found that there was no significant difference in TNB and NBA within the same parity,but from first to 7-9 parities,the TNB and NBA showed an upward trend,and there was no significant difference in the number of weaned piglets at 21 years of age.These data indicated that Meishan pigs have a long useful life,even after 7 parities,they still have excellent reproductive performance;at the same time,there is no significant correlation between the reproductive performance of each parity,and the reproductive performance of the early parity cannot be used to predict the later period fertility or early selection work3.In the process of crossbreeding utilization,Berkshire or Bamei pigs are used as male parents,and pure Meishan pigs are used as female parents.The TNB and NBA of the first parity are 13.10±2.04 and 12.56±2.05,respectively.The TNB and NBA were 13.59±2.15 and 13.09±2.09 respectively in second parity;the TNB and NBA of multiparous sows(?3 parities)were 14.80±2.57 and 14.20±2.36;but the born litter weight(LBW)and weaning litter weight(WLT)of their piglets were significantly higher than those of Meishan pure-bred piglets(P<0.05),indicating that Meishan pigs have a high hybrid combining ability as a female parent,which can be maintained by crossing with Berkshire Meishan pigs have excellent high-yield characteristics and effectively improve the production performance of Meishan pigs.However,the introduction of Berkshire pigs significantly reduced the number of total teats after crossing with Meishan pigs(17.05±0.79 vs 15.5±0.80)(P<0.001).4.The estrus identification of 110 Meishan pigs was carried out,and then serum samples were collected during artificial insemination(AI).The serum follicle-stimulating hormone(FSH),luteinizing hormone(LH),estradiol(E2)and progesterone(P4)at this moment were detected by radioimmunoassay.The pregnancy rate reached 90%of them,and the correlation analysis between serum reproductive hormones and littering traits showed that the FSH of sows with different total litter size and live litter size at the time of mating.There is no significant difference in serum content of,LH,estradiol(E2)and P4(P>0.05);in different parities(first parity,second parity,3-6 parities,7-9 parities),there was no significant difference in the levels of LH,E2 and P4,but the serum FSH levels of Meishan pigs at the second parity were significantly higher than the FSH levels of the 3-6 parities and 7-9 parities(P<0.05).The samples tested at this time are still small and the data is limited,so this result needs to be further studied.At the same time,in the 3-6 parity and 7-9 parity,the high-yield group(TNB?15)and Individual serum reproductive hormone levels in the low-birth group(TNB?10).The results showed that there was no significant difference in serum hormone levels between the high-birth group and the low-birth group in 3-6 parities(P>0.05);There was no significant difference in serum FSH,E2 and LH levels between the middle-high yield group and the low-yield group in 7-9 parities,but the progesterone of the high-yield group was significantly higher than that of the low-yield group(P<0.05),indicating that the high-level progesterone of the high-yield group maybe help the implantation of fertilized eggs,and improving embryo survival rate.Comprehensive analysis of the above results shows that Meishan pigs(medium-sized)maintained the excellent characteristics of high reproductive performance in the long-term preservation of breeds;and Meishan pigs have high cross-combining ability,which still maintain Meishan excellent characteristics of high yield of pigs also effectively improve the growth rate of piglets;and Meishan pig with high hybrid combining ability,which still maintain the high reproductive performance after hybrid with Berkshire,and the growth rate of piglets was improved effectively;the high level of serum progesterone during estrus and breeding of Meishan pigs may be one of the reasons for the high reproductive performance of Meishan pigs. |
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