| Based on the investigation of actual reproduction state of gilts in factory pig farm in Dongguang, the experiment of improving reproductivit\ of anestrous gilts by LHRH-A3 was conduced.1. The investigation of the reproductivity from hybrid gilts (Yorkshire Landrace) indicated that the estrus rate, conception rate and physiological anestrous rate in gilts was 71.98%, 84.18% and 22.80% respectively. Nursing 28 day or 35 day, the first-litter sow with medium weaning condition can shorten estrus-service interval (P<0.01), the anestrus rate of farrowing sow during weaning period was reduced (P<0.01). The estrus rate (P<0.01). the percent of concept sow farrowing(P<0.01), the live litter size(P<0.01) and the litter weights(P<0.01) in the second birth were improved.2. The results of using LHRH-A3 inducing estrous in anestrous gilts indicated that LHRH-A3 can promoted estrous in anestrous gilts and shorten the day open of first-litter sow, improved estrus rate and conception rate of anestrous gilts, and increased litter size. Comparing to the control group, the estrus-service interval was shortened by 7.24 day(7.14 day: 14.38day, P<0.01). the sow's post-weaning estrus ratio was increased by 54.37%(81.55%:27.18%. P<0.01). The estrus rate, conception rate were increased by 30.10 %( P<0.01), 15.87%( P<0.01) respectively. The average live litter size of firstborn and second birth were increased by 2.11%( 10.13:8.02;P<0.01), 1.94 (10.14:8.20; P<0.01) respectively.The results indicated that it was generally that the physiological anestrus in gilts. Using LHRH-A3 can adjusted the balance of reproduction endocrine'of anestrous gilts, improved the conception rate and the live litter size, shortened sow's post-weaning day open, reducd the culling rate of sow, and improved brood sow herd reproductivity and economic benefits of pig farm.
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