Knights M, Hoehn T, Lewis P E, Inskeep E K
Division of Animal and Veterinary Sciences, West Virginia University, Morgantown 26506, USA.
J Anim Sci. 2001 May;79(5):1120-31. doi: 10.2527/2001.7951120x.
The objectives of this study were to determine whether a new progesterone (P4)-releasing intravaginal insert would induce fertile estrus and whether FSH combined with the insert would increase prolificacy in anestrous ewes introduced to rams. Ewes of mixed breeding on six farms were assigned to four randomized treatments: control (C), n = 73; 12 d P4 (polycapralactone [PCL] insert with 0.82 g P4), (P12), n = 73; 12 d P4 plus i.m. FSH (Folltropin, 55 mg NIH-FSH-P1 equivalent) in propylene glycol, 24 h before insert removal, (P12F), n = 71; and 5 d P4 plus FSH (P5F), n = 77. Growth and ovulation of follicles were observed ultrasonographically in 20 ewes at four farms (five/treatment) at insert removal and 36, 48, 72, and 96 h later. Intact rams (1:15 ewes in multiple-sire groups) were joined at insert removal, and raddle marks were observed every 12 h for 5 d. On d 26 to 30, rams were removed; ewes were examined for pregnancy then and 20 d later. Percentage of ewes marked by rams was greater in P4-treated (66 to 79%) than in C (12%; P < 0.01) ewes and in P5F (79%) than in P12F (66%; P < 0.05). Diameters of largest follicles at insert removal were greater (P < 0.05) in P4-treated (5.5 +/- 0.2) than in C ewes (4.8 +/- 0.2). Progesterone increased numbers of follicles > 3 mm (P < 0.01) or ovulated (P < 0.05; 2.6 +/- 0.6 vs 1.3 +/- 0.6 in C ewes) and FSH increased number of follicles > 3 mm (P < 0.05). In FSH-treated ewes, ovulation rate tended to be greater after treatment with P4 for 5 than for 12 d (P = 0.09, 3.3 +/- 0.6 and 2.2 +/- 0.4, respectively). More P4-treated than C ewes lambed (P < 0.01) to the first (38 to 45 vs 0%) or both (63 to 66 vs 41%) service periods. Prolificacy (first service) did not differ between FSH-treated ewes (P12F + P5F; 1.8 +/- 0.1) and ewes treated with P4 only (P12; 1.6 +/- 0.1). However, FSH increased prolificacy to first service (1.8 +/- 0.1) over prolificacy to second service (C ewes 1.5 +/- 0.1; P < 0.05, and all ewes 1.4 +/- 0.1; P < 0.01). Pregnancy retention did not differ among treatments but was greater (P < 0.01) in ewes that conceived at the first (90.9 +/- 3.7) than at the second (72.5 +/- 3.3) service period. In conclusion, a PCL insert in combination with ram introduction at insert removal was more effective than ram introduction alone to induce synchronized estrus and ovulation and to yield pregnancy after one or two service periods. Treatment with P4 for 5 d was as effective as for 12 d to induce fertile estrus in FSH-treated anestrous ewes.
本研究的目的是确定一种新的释放孕酮（P4）的阴道内植入物是否会诱导发情排卵，以及促卵泡素（FSH）与该植入物联合使用是否会增加引入公羊的乏情母羊的繁殖力。六个农场的杂交母羊被随机分为四种处理：对照组（C），n = 73；12天P4组（含0.82 g P4的聚己内酯[PCL]植入物），（P12），n = 73；12天P4加在取出植入物前24小时肌肉注射FSH（促卵泡素，55 mg NIH-FSH-P1等效物，溶于丙二醇），（P12F），n = 71；以及5天P4加FSH组（P5F），n = 77。在四个农场的20只母羊（每种处理5只）取出植入物时以及之后36、48、72和96小时，通过超声观察卵泡的生长和排卵情况。在取出植入物时将成年公羊（多公羊组中母羊与公羊比例为1:15）放入，连续5天每12小时观察一次公羊爬跨标记。在第26至30天，将公羊移出；随后检查母羊是否怀孕，并在20天后再次检查。经P4处理的母羊（66%至79%）被公羊标记的比例高于对照组（C，12%；P < 0.01），P5F组（79%）高于P12F组（66%；P < 0.05）。取出植入物时，经P4处理的母羊（5.5±0.2）最大卵泡直径大于对照组母羊（4.8±0.2；P < 0.05）。孕酮增加了直径>3 mm的卵泡数量（P < 0.01）或排卵卵泡数量（P < 0.05；C组母羊为1.3±0.6，P4处理组为2.6±0.6），FSH增加了直径>3 mm的卵泡数量（P < 0.05）。在FSH处理的母羊中，P4处理5天的排卵率倾向于高于处理12天的（P = 0.09，分别为3.3±0.6和2.2±0.4）。经P4处理的母羊产羔数多于对照组母羊（P < 0.01），首次配种期（38%至45%对0%）或两次配种期（63%至66%对41%）均如此。FSH处理的母羊（P12F + P5F；1.8±0.1）与仅用P4处理的母羊（P12；1.6±0.1）首次配种的繁殖力无差异。然而，FSH使首次配种的繁殖力（1.8±0.1）高于第二次配种的繁殖力（C组母羊为1.5±0.1；P < 0.05，所有母羊为1.4±0.
