怎样养好种公兔

种兔是提高兔群质量、发展养兔事业的重要物质基础。种公兔饲养的好坏,与其配种能力及精液品质密切相关,并直接影响到母兔的受胎、产仔数及仔兔的生活力,千万不可忽视。一、影响种公兔配种能力的因素(一)营养对种公兔精液品质和配种能力的影响:种公兔的配种和精液品质主要受脑垂体机能制约。如果脑垂体机能降低,则影响促性腺激素的分泌,公兔表现性欲不强,精子     

促性腺激素释放激素并列体主动免疫对公猪性腺的影响

用GnRH并列体主动免疫公猪 ,并观察了免疫对公猪性腺的影响。结果表明 ,免疫使公猪睾丸体重降低 ,睾丸周长缩短 ,曲细精管管腔空荡 ,性腺萎缩     

公兔去势术

公兔性成熟后会出现好动、相互爬跨、撕咬现象,公兔3月龄后只能单笼饲养。商品兔及淘汰的种兔单笼饲养,则成本较高。公兔去势后性情温顺,饲料消耗减少,生产性能提高,减少对兔笼的啃咬破坏。肉兔和獭兔可提高增重速度和皮张质量,毛兔可提高产毛量,同时,也避免了散养兔群胡乱交配。去势后的公兔性腺萎缩,基本除去了公兔性腺特有的臊臭味,提高了肉品质量。     

獭兔种公兔饲养管理“四控制”

1控制体重过大 有人认为种公兔体重是种用价值的标志，即体重越大越好，这种观点是片面的、错误的。种公兔的种用价值不仅在于外表，而且重在能将其优良的品质遗传给后代，在于配种能力的高与低。一般来说，种兔的体重应适当控制，体型过大会出现的问题主要有：第一，发生脚皮炎的概率增大；     

用结扎法进行公兔去势

对不留作种用的公兔进行去势后,可达到以下效果:一是性情温顺,运动减少,减少饲料消耗.二是提高生产性能,对肉兔和獭兔可提高增重速度和皮张质量,对于毛兔可提高产毛量15%以上.三是便于兔群管理.去势公兔对兔笼的啃咬破坏减少,较少钻出笼外.同时,也避免了兔群胡乱交配情况的发生.四是经过去势的公兔会阴部性腺萎缩,宰杀后基本除去了公兔性腺特有的臊臭味,提高了肉品质量.     

如何得到健康的仔兔

1选好种公兔选择种公兔首先要求外貌要符合所选品种特征,符合生产方向的要求;其次要选择与欲配种母兔血缘关系远的种公兔,这样杂交优势才明显,再次要在满足上述条件的公兔群中选留体格健壮、生长速度快、睾丸发育匀称、性欲旺盛、配种能力强的青年公兔留作种用。2把握好种公兔的初配年龄在选好种公兔的基础上,关键要把握好种公兔的初配年龄,因为青年种公兔使用过早,不利于其生长发育;使用过迟,又不利于种公兔性欲的发挥。种公兔的初配年龄应比预留种母兔稍迟,应以8月龄为宜,肉兔种公兔的初配体重以4千克为宜,美系獭兔种公兔的初配体重以3千…     

獭兔种公兔饲养管理“四控制”

一是控制体重过大。不少人认为种公兔体重是种用价值的标志,即体重越大越好。这种观点是片面的、错误的。种公兔的种用价值不仅在于外表,而重在     

獭兔抗热应激制剂的研制

獭兔是多胎多产动物，具有常年发情、常年配种受孕的生理学基础。而兔又身被绒皮，汗腺不发达，炎热的气候条件往往会导致獭兔生长缓慢，母兔发情不规律，公兔精液品质下降，造成很大损失。本研究进行了抗热应激制剂的筛选试验。 1材料与方法 1.1试验兔的选择和分组 1.1.1选择 50只 60日龄左右的獭兔，体重相近，随机分为 5组，试验前进行驱虫和常规免疫，供生长育肥饲养试验之用。 1.1.2选择 6月龄公兔 30只，测定抗热应激制剂对精液品质的影响。 1.1.3选 1岁左右经产母兔 40只，随机分 5组，测定抗热应激制剂对母兔繁殖性能的影响。 1.2抗…     

家兔如何配种成功率高

<正>(一)适龄配种繁殖一般母兔达到7月龄,体重2.5千克左右,公兔达到9月龄,体重3千克左右时配种繁殖较好;壮年种公兔配壮年种母兔为最佳,1只公兔可配     

提高仔兔成活率的技术措施

１加强选种配种，科学饲养母兔是提高仔兔成活率的基础种母兔要选择体重适中、母性好、泌乳力强、产仔数多、性欲旺盛的母兔。种公兔要求体质好、配种能力强的正常公兔作为种兔。并非配得次数越多越好。虽然胎儿数量上去了，但却造成胎儿营养不足，个体体重下降，哺乳也增...     

GnRH并列体二聚体主动免疫对雄兔血清睾酮的影响

用GnRH并列体二聚体主动免疫雄兔,并观察了免疫对雄兔血清睾酮与睾丸重量的影响。结果表明该方法能使雄兔血清睾酮水平降低,睾丸重量下降。     

促性腺激素释放激素类似肽主动免疫对公猪生殖机能的影响

10头公猪在3月龄时用促性腺激素并列体二聚体(GnRHTD)主动免疫,观测内源GnRH被免疫中和所产生的内分泌和生殖机能的变化。注射GnRHTD与卵清蛋白(OVA)的偶联物2次,结果发现GnRHTD主动免疫能降低外周血清睾酮浓度,睾丸重量也明显下降。组织切片显示,曲细精管有少数退化的精原细胞。这些变化表明:公猪接种GnRHTDOVA能诱发免疫反应,中和内源GnRH的生物活性,且抑制睾酮的合成,从而导致性器官发育受阻。     

Reproductive function and feedlot performance of beef heifers actively immunized against GnRH1

Two trials were conducted to examine reproductive function and feedlot performance by heifers after active immunization against GnRH. In trial 1, heifers were not immunized or were immunized with one of three doses of a GnRH-KLH (keyhole limpet hemocyanin) conjugate in Freund's complete adjuvant. Antibodies against GnRH were not detectable in non-immunized heifers (n = 9). However, antibodies against GnRH were noted in all immunized animals (n = 30) within 8 wk of primary immunization; anti-GnRH antibody concentrations were at a maximum 16 to 20 wk after immunization. This increased anti-GnRH titer was associated with a decreased serum concentration of progesterone. Ovarian and uterine weight and tissue concentrations of LH and GnRH receptor were reduced (P less than .05) by immunoneutralization of GnRH. Similarly, immunization against GnRH reduced (P less than .05) weight gain during feedlot confinement. In trial 2, feedlot performance after insertion of anabolic steroid implants (Synovex H) was evaluated in non-immunized heifers (n = 15), heifers actively immunized against GnRH-KLH (n = 15) or KLH alone (n = 15), or non-immunized heifers treated with melengestrol acetate (MGA; n = 15). Serum concentrations of progesterone were depressed in anti-GnRH and MGA-fed groups, but ovarian and uterine weights were depressed (P less than .05) only in heifers immunized against GnRH. Total weight gain and gain during the final 4 wk of confinement did not differ (P greater than .05) among groups with steroid implants. The GnRH-KLH conjugate is an effective immunogen in heifers, leading to suppression of reproductive activity. The depression of weight gain that attends development of anti-GnRH titers may be reversed by use of implants that contain anabolic steroids.     

Pituitary and testicular responses of beef bulls to active immunization against inhibin alpha

Prepubertal crossbred beef bulls served as controls or were actively immunized against the N-terminal, 30-amino acid synthetic fragment of porcine inhibin alpha, pI alpha (1-30). Antibody titers were detected in sera (greater than 40% B/BO in sera diluted 1,000-fold) but not in rete testis fluid of 390-d-old bulls. Serum FSH and inhibin remained static during a 5-h intensive bleed; inhibin was not acutely affected by a 15-fold LH rise and a threefold FSH rise induced by exogenous GnRH. Serum FSH, but not LH or testosterone, was consistently elevated (P less than .05) in immunized bulls compared with control bulls. Neither pituitary weight, pituitary gonadotropin content nor pituitary FSH/LH ratios were affected (P greater than .10) by pI alpha(1-30) active immunization. Testicular sperm density was greater (60 x 10(6) vs 45 x 10(6) sperm/g testis; P less than .10) in immunized bulls, but testes weight, epididymides weight and total daily sperm production remained unchanged. These results suggest that inhibin is important for regulation of FSH secretion and testicular function. Immunization with suitable inhibin vaccines may improve bull fertility.     

Feedlot performance of steers and bulls actively immunized against gonadotropin-releasing hormone.

Feedlot performance and testicular and pituitary function were assessed in cattle actively immunized against GnRH. In Trial 1, 50 steers were either unimmunized (n = 10), actively immunized against keyhole limpet hemocyanin (KLH; n = 10), or immunized against a GnRH-KLH conjugate (n = 30). Fifteen of 30 steers immunized against GnRH-KLH received a secondary immunization 8 wk after primary immunization. Antibodies against GnRH were not evident in unimmunized steers or steers actively immunized against KLH. Antibodies against GnRH were noted in all immunized animals (n = 30) within 6 wk of primary immunization and anti-GnRH antibody concentrations became maximal 20 to 24 wk after immunization. The increasing anti-GnRH titer in immunized steers was associated with decreasing serum concentrations of LH. Serum concentrations of LH were depressed (P less than .05) within 8 wk of primary immunization and reached a nadir by wk 20. The patterns of increase in GnRH titer and decrease in serum concentrations of LH did not differ (P greater than .05) in animals receiving primary immunization alone or primary and secondary immunization. Feedlot performance and carcass quality were not affected (P greater than .05) by immunization against KLH or the GnRH-KLH conjugate. In Trial 2, 60 bull calves (mean weight = 325.2 +/- 2.8 kg) were randomly assigned to a 2 x 3 factorial experiment. The two classes (n = 30) were 1) unimplanted and 2) implanted with Synovex-S. The three treatments (n = 20) were 1) intact control, 2) actively immunized against GnRH, and 3) castrate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Performance of male pigs immunized against GnRH is related to the time of onset of biological response

In this study, the performance of male pigs immunized against GnRH was determined in relation to the onset of their biological response to the immunization. Pigs were immunized at 9 and 17 wk of age and were housed in a pen together with both a surgically castrated and an intact boar littermate. Feed intake was restricted to 2.8 to 3.2 times maintenance requirement for energy. Animals were weighed weekly and slaughtered at 108 kg BW. Depending on the time of onset of the response after immunization in terms of biological effects, immunized pigs were retrospectively grouped into two categories. One category consisted of the immunized pigs, which had undetectable or low levels of LH and testosterone at the time of booster immunization-known as "early" responding immunocastrates (E-IM, n = 8), whereas the "late" responding immunocastrates (L-IM, n = 7) had substantial LH and testosterone levels at that time. This dichotomy of the response to immunization also was reflected in testis weight, with 17 g and 40 g for E-IM and L-IM pigs, respectively. At slaughter, testis size and weight were reduced (P < 0.001) in the immunocastrated pigs as compared to the intact boars. Androstenone concentrations in backfat of all immunocastrated pigs were undetectable. Growth performance (i.e., ADG and feed efficiency [FE, g gain/kg feed]), was better in boars and L-IM pigs than in surgical castrates and E-IM pigs (P < 0.05). Average daily gain and FE did not differ between E-IM pigs and the surgical castrates, but intact boars performed better than L-IM (P < 0.02). There were no significant differences in carcass quality (backfat thickness and meat percentage) between boars and surgical castrates at slaughter. However, for both characteristics L-IM pigs and intact boars performed better (P < 0.03) than E-IM pigs. Thus, growth performance in L-IM is better than in either E-IM or surgical castrates.     

GnRH类似物疫苗免疫去势效果的影响因素

利用GnRH类似物疫苗主动免疫动物机体可达到与手术去势类似的效果,同时避免了手术去势对动物机体产生的影响。抗原、佐剂、免疫次数、免疫剂量以及免疫时间都会对其免疫效果产生影响。采用GnRH类似物疫苗免疫动物通常需要有力的佐剂以及多次加强免疫来克服个体反应的差异性。     

Immunization of beef heifers against gonadotropin-releasing hormone prevents luteal activity and pregnancy: Effect of conjugation to different proteins and effectiveness of adjuvants

Three experiments were conducted to evaluate methods of immunization against GnRH on antibody titer, luteal activity, and pregnancy in beef heifers. Experiment 1 evaluated the efficacy of adjuvants with 30 heifers. Control heifers were immunized against human serum albumin (HSA) emulsified in Freund's complete adjuvant (FCA). The other 4 treatments contained GnRH conjugated to HSA (HSA-GnRH) emulsified in FCA, Freund's incomplete adjuvant (FIA), DEAE dextran (DD) + mineral oil (MO), or DD+FIA. Treatment was in the mammary gland for all experiments. Titers against GnRH for heifers immunized against HSA-GnRH with FCA, DD+MO, or DD+FIA were greater than titers for HSA-GnRH with FIA or control heifers (P < 0.01). Body weight was reduced (P < 0.05) in control and FCA heifers compared with FIA, DD+MO, and DD+FIA heifers. Heifers immunized with DD+MO and DD+FIA had fewer granulomas in mammary glands than heifers treated with FCA (P < 0.01). In Exp. 2, 36 heifers were used to determine the effect of the protein conjugated to GnRH on titers against GnRH. Heifers (6/treatment) received a primary immunization against GnRH conjugated to HSA (HSA-GnRH), ovalbumin (OA-GnRH), or keyhole limpet hemocyanin (KL-GnRH), or heifers were immunized against each carrier protein. Antigens were emulsified in DD+FIA. Immunization of heifers against OA-GnRH, KL-GnRH, or HSA-GnRH suppressed luteal activity (P < 0.01) for 23, 16, and 12 wk, respectively, and antibody titers against GnRH were greater (P < 0.01) for 19, 5, and 7 wk, respectively, compared with heifers immunized against the carrier proteins. In Exp. 3, 90 heifers were used to determine the effect of immunization against GnRH on ovarian activity and pregnancy rate. Heifers (30/treatment) received a primary and 2 or 3 booster immunizations against GnRH conjugated to OA, and controls received a primary and 2 booster immunizations against OA. All antigens were emulsified in DD+FIA. At 8 wk after primary immunization, heifers were exposed to fertile bulls for 24 wk. Pregnancy rate was less (P < 0.01) for 3-booster heifers (13%) compared with control (83%) and 2-booster (62%) heifers. We conclude that immunization against GnRH, conjugated to OA and emulsified in DD+FIA, does not influence ADG and produces sufficient titers against GnRH to prevent estrous cycles with few mammary granulomas. Immunization against GnRH with 3 booster immunizations prevented luteal activity and pregnancy in most beef heifers for more than 4 mo.     

Stimulation of annexin A5 expression by gonadotropin releasing hormone (GnRH) in the Leydig cells of rats

The distribution and regulation of annexin A5 expression, a gonadotropin releasing hormone (GnRH) receptor regulated protein in gonadotropes and luteal cells, in the testes of rats were examined. Immunocytochemical staining revealed high levels of annexin A5 in the Leydig and endothelial cells and lower levels in the primary spermatocytes and sperm. Hemicastration significantly increased the annexin A5 content of the remaining testis within 24 h. Annexin A5 immunoreactivity was increased mainly in interstitial tissues including the peritubular cells, while some spermatocytes also showed higher intensity of annexin A5 in the remaining testis. Administration of hCG (50 IU) enhanced the testicular content of annexin A5 after 24 h. This treatment expanded the area of interstitial tissue in the testis and increased annexin A5 immunoreactivity, but the area of the of endothelial cells was unchanged. Similarly, human chorionic gonadotropin (hCG) enhanced annexin A5 expression in a primary culture of testis cells that consisted of mainly interstitial cells. Because GnRH stimulates the expression of annexin A5 in the gonadotropes and luteal cells, we examined the effect of GnRH on annexin A5 expression in the testes. We found that des-Gly10 [Pro9]-GnRH ethylamide (100 nM), a GnRH agonist, increased annexin A5 expression in cultured testis cells and that Cetrorelix (100 nM), a GnRH antagonist, inhibited the effect of hCG on annexin A5 expression. These results suggest that pituitary luteinizing hormone promotes annexin A5 synthesis in Leydig cells and that this effect could be mediated by local GnRH in the testis.     

GnRH-Ⅰ疫苗免疫效果影响因素、商业困境与免疫机理研究进展

哺乳动物中除豚鼠外GnRH-Ⅰ的主要序列和结构都是完全一致的，所以GnRH-Ⅰ疫苗的应用范围广。在动物去势及避孕和人类免疫治疗研究中显示了其无可比拟的优越性。本文综述了GnRH-Ⅰ疫苗的免疫机理、免疫效果的影响因素及其商业化的困境。