探讨延长光照对母貂体内孕酮(progesterone,P4)水平和繁殖性能的影响.试验随机选择120只母貂,随机平均分为控光组和对照组,控光组从母貂配种结束开始至约1/2母貂产仔结束期间有规律的延长光照,对照组母貂只接受自然光照;试验自准备配种后期、配种期、妊娠期每隔1d和产仔后连续3d分别收集2组母貂的鲜粪,采用酶联免疫法测定粪中P4含量并统计母貂的妊娠时间、胎平均产仔数等指标.结果表明:延长光照前19d2组P4在738.2 pmol/L水平波动(P>0.05);施加光照后,控光组P4水平逐渐上升并于第6d升至峰值l 213.65 pmol/L,较对照组提前2 d (P<0.05);然后P4缓慢下降,至第38 d波动于825.48 pmol/L水平(P<0.05);随后逐渐下降至第49 d两组P4在729.47 pmol/L水平波动(P>0.05).控光组母貂平均妊娠期47.76 d,胎平均产仔数为5.75只,仔貂3日龄成活率82.91%.由此说明,从配种落点开始,对母貂有规律的延长光照可使P4提前2d达到峰值,有利于胚泡早着床;母貂妊娠期缩短1.84 d (P<0.05),胎平均产仔数增加1.28只(P<0.05),仔貂3日龄成活率提高12.03% (P<0.05),75.0%母貂于6日内集中产仔.
Effects of Light Control on Mink's Progesterone Level in vivo and Reproductive Performance in Breeding Season
The aim of this study was to investigate the effects of extended light on progesterone level in vivo and reproductive performance of female mink.120 female minks were randomly selected and divided into two groups in average,the light control group and the control group.Minks in the light control group were given regular extra light when they completed mating,until half of them gave birth.At the same time,minks in the control group were only accepted natural light throughout all the experiment.Results showed that,progesterone levels in the two groups were fluctuating in 738.20 pmol/L in the first 19 days before extending light (P>0.05).After light controlling,the progesterone level of light control group rose significantly,and peaked at 1213.65 pmol/L on the 6th day,which was 2 days in advance (P< 0.05).Then the progesterone level of light control group declined gradually and fluctuating in 825.48 pmol/L at the 38th day,which was significantly higher than that of control group (P<0.05).At the 49th day it had declined to 729.47 pmol/L near to the control group (P>0.05).The average gestation days and the average little size per mink of light control group were 47.76 and 5.75 respectively,and the survival rate of 3-day-old minks was 82.91 percent.Thus it can be seen that giving regular extra light benefited to pregnant minks in the following ways.The progesterone level in vivo could peak 2 days in advance,then affecting the embryos implanting earlier.The average gestation period reduced 1.84 days (P<0.05).The average little size per mink and the survival rate of 3-day-old mink were all increased,by 1.28 (P<0.05) and 12.03% (P<0.05) respectively.About 75.0 percent of pregnant minks had concentrated their time of giving birth in 6 days.