乏情奶牛日粮营养水平和血浆生殖激素的变化

选取产后65～75天无发情表现的泌乳奶牛，经直检分为卵泡闭锁（Ⅰ）、卵巢囊肿（Ⅱ）、持久黄体（Ⅲ）和排卵延迟（Ⅳ）4组，每组10头奶牛。应用放射免疫测定法检测每头奶牛血浆FSH、LH、E2、P4的水平，同时分析该牛场此时期日粮中营养水平。结果表明：饲料中能量、蛋白质和磷的含量低于NRC（2001）水平。4个组奶牛血浆中的FSH含量均低于正常水平；Ⅰ组血浆中的E2含量低于同期正常水平；Ⅱ组血浆中的E2含量高于正常水平；Ⅲ组血浆中的E2含量低于正常水平，P4的含量高于正常水平；Ⅳ组血浆中的E2含量高于正常水平，P4和LH的含量低于正常水平。结论：日粮能量、蛋白和磷含量较低导致的泌乳奶牛生殖激素的紊乱是引起奶牛乏情的主要因素。     

Effect of Repeated Cabergoline Treatment on the Vernal Transition and Hair Shedding of Mares (Year 1) and a Subsequent Comparison of the Effect of Starting Date on Prolactin Suppression (Year 2)

Two studies were conducted to determine efficacy of cabergoline for suppressing prolactin (PRL) and the possible effects on vernal transition in mares. In experiment 1, six mares each received either vehicle or cabergoline (5 mg, intramuscularly) every 10 days for 12 treatments beginning February 4, 2013. Blood samples were drawn regularly, and mares were challenged with sulpiride periodically to assess PRL suppression. Weekly hair samples were obtained to determine shedding. Prolactin was suppressed (P < .05) by cabergoline, but suppression waned in spring. There was no effect (P > .05) of treatment on day of first ovulation, luteinizing hormone, or follicle stimulating hormone. Hair shedding was generally suppressed (P = .05). In 2014 (experiment 2), eight of the same 12 mares were used in a similar experiment to determine if the rise in PRL observed in experiment 1 was due to refractoriness to cabergoline or perhaps another factor. Treatment began on April 6, 2014, corresponding to the increase in PRL in treated mares in experiment 1. Mares were treated with cabergoline or vehicle until June 5. Prolactin was suppressed (P < .05) by cabergoline, and the pattern of apparent escape from suppression was similar to year 1. We conclude that (1) cabergoline at this dose alters hair shedding but does not alter the time of first ovulation in mares and (2) relative to our previous reports of cabergoline treatment in the fall, there is a seasonal effect on the ability of this dose of cabergoline to suppress unstimulated PRL secretion.     

Use of Acupuncture to Induce Cyclicity in Anestrous Mares

Acupuncture is part of an Eastern system of medicine used for diagnosing, treating, and preventing disease. It has been used for the treatment of reproductive disorders in both human beings and domestic species. We hypothesized that acupuncture could be used to induce cyclicity in anestrous mares. In experiment 1, six anestrous mares were treated with acupuncture at Bai Hui, governing vessel (GV)-2, bladder (BL)-22, BL-23, BL-31, and BL-33 twice a week for 3 weeks, then once a week for an additional 8 weeks, whereas six anestrous mares served as controls. In experiment 2, six anestrous mares received acupuncture stimulation at Bai Hui, GV-1, BL-22, BL-23, and BL-28, with electroacupuncture (10 minutes at 50 Hz) at BL-22 and BL-28 bilaterally. In addition, vitamin B12 (3 mL, 1,000 mcg/mL) was injected in the vaginal fornix at the 3, 6, and 9 o’clock positions around the cervix. Six anestrous mares served as controls. Examinations and treatments were carried out twice a week until ovulation. In both experiments, ovarian activity was examined in all mares by transrectal ultrasonography and blood sample was obtained twice a week to determine progesterone concentrations. The time to first ovulation for experiment 1 was 14.0 ± 0.7 and 13.5 ± 1.0 weeks (mean ± SD) for the control and acupuncture groups, respectively (P = .60). In experiment 2, the time to ovulation was 9.0 ± 0.6 and 10 ± 0.3 weeks (mean ± SD) for the control and acupuncture groups, respectively (P = .19). No significant difference was found between the treated and control mares in either study.     

Insulin-like growth factor I in sera, ovarian follicles and follicular fluid of cows with spontaneous or induced cystic ovarian disease

The objective of this research was to determine changes in IGF-I levels in serum and follicular fluid, and immunoreactivity of the follicle wall of cows with spontaneous (slaughter specimens) or ACTH-induced follicular cysts, and to compare results to normal cycling (control) cows after selection of the ovulatory follicle. Concentrations of IGF-I in serum did not differ between control and cystic animals (p=0.76). Fluid from the ovulatory follicle in control cows had 41% higher concentrations of IGF-I than that from cystic follicles collected at slaughter (spontaneous cysts; p<0.05) and 70% higher than that in induced follicular cysts (p<0.05). An intense positive immunostaining with anti-IGF-I was observed in granulosa cells (p<0.05) and in the theca interna (p<0.05) of secondary and tertiary follicles in all three groups of animals, but staining was less intense in cystic (p<0.05) and atretic follicles (p<0.05). This study provides evidence to suggest that cystic ovarian disease in cattle is associated with decreased concentrations of IGF-I in follicular fluid, but not in serum, and decreased production of IGF-I in the follicular wall. These data support the notion that IGF-I plays a role in the regulation of folliculogenesis, and may participate in the pathogenesis of cystic ovarian disease in cattle.