枫泾小猪生殖机能的发展和孕酮含量的测定

在枫泾小公猎生殖机能发展的试验中,用小公猪4头,从3月龄开始至7月龄,每个月龄都与6～8月龄母猪配种,共配22头,受胎率分别为40%(2/5)、100%(5/5)、50%(1/2)、66.7%(2/3)和85.7%(6/7),妊娠28天胚胎数量、重量和分娩仔猪数、初生重都达成年公猪所配的效果。表现枫泾小公猪3月龄已属发身期,配种后可使母猪受胎,4.5月龄已属性成熟期,具有充分的受精能力。在枫泾小母猪生殖机能发展试验中,用小母猪25头,分成5组,分别在初情期到第五情期,各用成年公猪精液配种,受胎率分别为20%(1/5)、100%(5/5)、100%(5/5)、100%(5/5)和60%(3/5);排卵数分别为13.0、12.2、14.8、14.8、和16.6。小母猪妊娠28日龄胚胎的大小与大母猪28日龄胚胎的相似。小母猪各情期孕酮含量高水平之间,各情期妊娠早期孕酮含量高水平之间,差异均不显著(P>0.05)。情期第9天和第12天孕酮水平为27.4ng/ml 和29.6ng/ml,妊娠第9天和第12天为21ng/ml 和26.8ng/ml,与8～10月龄大母猪的孕酮水平相似。上述受胎率和孕酮水平均表明枫泾小母猪113.2日龄(体重18.9公斤)已属初情期,可以配种受胎;135.8日龄(体重23.2公斤)已属性成熟期,具有充分的受胎能力。     

不同断奶至配种间隔天数对大白纯种母猪失配率和窝产仔数的影响

为研究基础母猪最佳断奶天数,对温氏西北区域某原种场批次化内所有断奶母猪的失配率、总产仔数等数据进行统计分析。结果显示,该场的第7至第11批次母猪断奶至配种间隔天数分布较为广泛,最低2天,最高达到8天。断奶至配种间隔天数为4天、5天、6天的配种率较为集中。断奶至配种间隔天数分别为3、4、5天的窝产仔数差异不显著,但断奶至配种间隔为3天的失配率最低。第7至第17批次母猪以及超期猪和后备猪的失配率数据统计结果表明,后备猪和断奶7天配种的母猪失配率分别达12.48%、12.82%,断奶8天配种的母猪失配率最高,达37.5%。超期猪的失配率也较高,为10.20%。配种率较大的断奶至配种间隔天数集中在4～6天。单从失配率指标考虑,断奶后3～6天失配率较低,断奶后4天配种失配率最低,为4.25%。结论:1)断奶至配种间隔天数对经产母猪繁殖性能影响显著。2)基于该场采用深部两次输精的模式,断奶后适当提前配种有利于提高繁殖成绩。3)该试验条件下该场断奶至配种间隔天数为3～5天配种可获得最佳的繁殖性能。     

母牛早期妊娠诊断——应用放射免疫测定乳汁孕酮在母牛性周期内变化规律的试验报告

应用放射免疫法对10头黑白花母牛性周期内乳汁孕酮含量进行了测定。结果显示母牛配种当天(0天)乳汁不含孕酮,配种后第3天含量仍是低值(范围0—4ng/ml,平均0.71±1.338)。以后逐渐上升,配种后第13天,70%个体出现峰值(范围14.8～36.5ng/ml,平均24.9±6.73);其余个体于配种后第16天出现峰值(范围15—31ng/ml,平均24.83±8.6)。此后显示分化现象,其波动曲线与同类报道相似。     

配种前不同能量水平饲粮对断奶母猪生产性能的影响

为研究配种前不同能量水平饲粮对断奶母猪生产性能的影响,试验选择380头、体况相近、2~7胎长白×大约克杂种断奶母猪,根据胎龄、体况等按随机区组分为3组。断奶当天开始分别饲喂消化能12.97 MJ/kg、13.60 MJ/kg和14.23 MJ/kg的3种饲粮,其他营养指标相同。结果表明:1)14.23 MJ/kg组窝均总仔数比13.60 MJ/kg组和12.97 MJ/kg组分别提高0.07头(P>0.05)和0.28头(P>0.05),窝均健仔数分别提高0.13头(P>0.05)和0.28头(P>0.05);2)14.23 MJ/kg组配种分娩率最高,但各组差异不显著(P>0.05)。结果提示,建议配种前适当提高饲粮能量水平,有利于提高断奶母猪的繁殖性能。     

仔猪不同日龄断奶母猪生产表现比较试验

选择同一胎次长大母猪18头与杜洛克公猪杂交产生18窝仔猪,共分3组,每组6窝,分别于21、28、35日龄断奶。各阶段分别饲喂妊娠母猪料(配种～21天,1.8千克/天;22～84天,2.2千克/天;85～108天,2.8千克/天)、哺乳母猪料(配种后的108天至仔猪断奶,3千克/天)、乳猪颗粒料。结果统计各项指标如表1。不同断奶日龄日增重差异显著(P<0.05),但断奶～60日龄育成率差异不显著(P>0.05)。21日龄与28日龄组相比,繁殖周期缩短6.5天,每年可提高0.12胎次;21日龄与35日龄断奶相比,繁殖周期缩短13.2天,每年可提高0.23胎次。可见正确实施早期断奶可提高母猪利用率,…     

母猪分阶段的饲养管理方法

1提高排卵率时期（断奶～配种） 从断奶至配种饲喂哺乳料，要最大限度的增加采食量，这不仅能使母猪尽快恢复哺乳期间的体重损失，也能提高母猪的排卵率。最好断奶当天不要断食断水，如断奶当天断食断水，就会使母猪再发情日延长1-2天。     

类卵泡刺激素和人绒毛膜促性腺激素对后备母猪诱情效果及繁殖性能的影响

后备母猪初情期推迟,导致繁殖性能和利用率低。试验通过促性腺激素诱导长大二元杂种后备母猪发情,以期提高其繁殖性能和利用率。以类FSH(卵泡刺激素)和HCG(人绒毛膜促性腺激素)处理6.5月龄后备母猪,激素诱导组1周内75.58%的后备母猪出现发情,第2次规律发情比例为67.44%,而空白对照组分别为6.80%和44.22%;激素诱导组首次配种日龄和配种时的情期数分别为259天和2.72次,与空白对照组的266.5天和1.84次,差异达显著和极显著水平;激素诱导组利用率比空白对照组提高12个百分点;激素诱导组母猪第1胎断奶至配种的时间间隔为6.31天,显著短于空白对照组9.47天。后备母猪当胎的分娩率、窝均总产仔数、窝均合格仔数和第1胎断奶后发情配种率等指标,激素诱导组和空白对照组差异均不显著。可见,激素诱导后备母猪发情可显著使母猪的初情期提前,繁殖性能和利用率提高。     

长白母猪断奶至配种间隔时间与下一产的产仔数之关系

母猪的断奶至配种间隔的时间是母猪一个繁殖周期的组成部分 ,它的时间长短不但影响母猪的年产胎数 ,同时也制约着下一产的产仔数。本文通过母猪断奶至配种间隔时间与下一产的产仔 (活 )数及与母猪胎龄、产仔季节之关系统计分析 ,阐明提高母猪生产水平必须注意的几个问题。1　资料来源江苏淮阴江淮农业发展有限公司 2 0 0 0年长白母猪的繁殖与配种记录 ,共 1 85胎 ;母猪哺乳期 2 8天。统计母猪胎龄 ,断奶时间 ,下一产的配种日期 ,产仔(活 )数 ,进行分析。2　统计结果2 1　 1 85胎长白母猪的断奶至配种间隔的平均时间为 7 45± 4 5 6天。最长…     

妊娠期不同营养方式对母猪繁殖性能的影响

试验旨在研究不同营养方式对母猪繁殖性能的影响。选择胎次、体重相近、发情期相近空怀的长×大母猪60头,分为3组,每组10个重复。试验日粮营养分低水平营养(日粮1)和高水平营养(日粮2);第1组在发情配种之日开始饲喂日粮1至分娩,第2组在配种之日开始饲喂日粮2至分娩,第3组配种之日连续30 d饲喂日粮1,而后经过7 d过渡期逐渐转为日粮2至分娩。分娩后所有母猪都饲喂哺乳日粮至断奶。结果表明:①第3组产仔数分别比1组、2组提高12.49%(P<0.05)和12.08%(P<0.05);②第3组产活仔数分别比1组、2组增加17.35%(P<0.05)和21.00%(P<0.05);③平均出生个体重以第2组最高,差异不显著;但28日龄断奶窝重则以第3组最高,分别比1组、2组提高41.06%(P<0.05)和21.50%(P<0.05)。④不同营养方式对母猪情期受胎率没有影响,但低营养水平可延长发情间隔(P>0.05)。前低后高营养方式使母猪产仔数、产活仔数和28日龄断奶窝重显著提高;不同营养方式对仔猪平均出生个体重、母猪的发情间隔及情期受胎率没有显著影响。     

母鹅抱窝期间血浆中PRL、P和17β—E2水平的变化

选择表现抱窝行为的母鹅7只,通过RIA方法测定了母鹅在抱窝期间PRL(催乳素)、P(孕酮)和17β—E2(雌二醇)水平的变化。抱窝伊始P、17β—E2含量分别为3.28±0.27ng/ml、71.74±6.45pg/ml。抱窝第11天17β—E2水平降至49.07±8.48pg/ml(P>0.05),而P水平略有升高直至第18天才出现显著下降(1.864±0.12ng/ml)。雏鹅孵出后P、17β-E2水平分别回升至2.71±0.29ng/ml(P>0.05)、142.86±19.00pg/ml(P<0.01)。休产期间P、17β—E2水平均表现一定程度的降低。血浆中PRL水平第一天为214.24±19.73uU/ml。以后呈缓慢上升趋势,抱窝第25天达到高峰395.89±29.75uU/ml(P<0.01),雏鹅孵出后PRL下降至276.32±16.10uU/ml(P<0.05),抱窝结束后PRL水平进一步降低,休产期间PRL降至最低点55.94±15.35uU/ml(P<0.01)。研究表明:PRL可以诱导以及维持母鹅表现抱窝行为,并可抑制卵巢性腺激素的生成与释放。     

Leptin and ghrelin levels in colostrum,milk and blood plasma of sows and pig neonates during the first week of lactation

Radioimmunology was used to determine leptin and ghrelin levels in sow colostrum and milk in relation to those in sow and neonatal pig blood plasma and to the body weight of piglets during the first week of lactation. The highest concentration of leptin was found in colostrum on the second day of lactation (69.3 ± 6.3 ng/mL). Leptin concentrations in sow plasma were significantly lower than in colostrum/milk (2.19 ± 0.9 ng/mL, P = 0.7692) and were stable in the first 7 days of lactation. Total and active ghrelin concentrations in colostrum/milk were stable in the measured time points (6734 ± 261 pg/mL, P = 0.3397; 831 ± 242 pg/mL, P = 0.3988, respectively). Total ghrelin concentrations in sow plasma were lower than in colostrum/milk. These results indicate that pigs follow a unique species‐specific pattern of leptin and ghrelin synthesis, release and existence, and that the mammary gland is an important source of leptin and ghrelin contained in colostrum/milk.     

Effects of sample handling on adrenocorticotropin concentration measured in canine plasma, using a commercially available radioimmunoassay kit.

A commercially available radioimmunoassay (RIA) kit for measurement of human adrenocorticotropin (hACTH) was validated for use in dogs. Assay sensitivity was 3 pg/ml. Intra-assay coefficient of variation (x 100; CV) for 3 canine plasma pools was 3.0 (mean +/- SD, 33 +/- 0.99 pg/ml), 4.2 (71 +/- 2.4 pg/ml) and 3.7 (145 +/- 3.7 pg/ml) %. Interassay CV for 2 plasma pools measured in 6 assays was 9.8 (37 +/- 3.6 pg/ml) and 4.4 (76 +/- 3.4 pg/ml) %, respectively. Dilutional parallelism was documented by assaying 2 pools of canine plasma at 3 dilutions and correcting the measured result for dilution. Corrected mean concentrations for the first pool were 33 (+/- 0.99), 36 (+/- 4.3), and 33 (+/- 6.8) pg/ml; corrected mean concentrations for the second pool were 145 (+/- 5.4), 141 (+/- 10.8) and 125 (+/- 3.4) pg/ml. Recovery of 1-39hACTH added to canine plasma (6.25, 12.5, 25.0, 50.0, and 100.0 pg/ml) was linear and quantitative (slope = 0.890, R2 = 0.961). To test whether anticoagulant or the protease inhibitor, aprotinin, influences ACTH concentration in canine plasma, ACTH was measured in canine blood collected in 4 tubes containing anticoagulant: heparin (H), heparin + 500 kallikrein inhibitor units (KIU) of aprotinin/ml (HA), EDTA (E), and EDTA + aprotinin (EA). Plasma ACTH concentration was the same when samples containing H and HA, or HA and E were compared, and was significantly (P less than 0.01) lower in samples containing EA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Function of prostaglandins, thromboxane A2, and histamine in hypersensitivity reaction to experimental bluetongue disease in calves

Calves given 2 subcutaneous inoculations (4 ml, 4.5 weeks apart) of an inactivated bluetongue virus serotype 17 (BTV-17), aluminum hydroxide adjuvant, and cimetidine (600 mg) or levamisole (819 mg, 6 ml) combination were challenge exposed with virulent BTV-17 (2.5 x 10(5) embryo lethal dose) 9 weeks after the 1st inoculation and were monitored for 35 days. Plasma prostaglandins (PG) and thromboxane (Tx) B2 were measured by radioimmunoassay. Histamine was assayed spectrofluorometrically. During the inoculation period (9 weeks from the 1st inoculation to challenge exposure) PGE and histamine increased from base-line concentrations of 34 +/- 3 pg/ml and 1.2 +/- 0.1 ng/ml to 83 +/- 8 pg/ml and 2.0 +/- 0.1 ng/ml, respectively, whereas PGF2 alpha decreased from base-line values of 356 +/- 41 pg/ml to 226 +/- 16 pg/ml. Significant (P less than or equal to 0.05) changes from base-line TxB2 values (110 +/- 7 pg/ml) were not observed during the inoculation period. After challenge exposure, maximum increases were observed in TxB2 (157 +/- 10 pg/ml), PGF2 alpha (713 +/- 93 pg/ml), PGE (140 +/- 30 pg/ml), and histamine (3.6 +/- 0.2 ng/ml) concentrations at 4, 7, 7, and 14 days after challenge exposure, respectively. Concentrations of PGF2 alpha and TxB2 decreased from base-line values to 211 +/- 42 pg/ml and 75 +/- 11 pg/ml, respectively, 21 days after challenge exposure and then returned to base-line values. Significant changes were not observed in plasma concentrations of 6-keto-PGF1 alpha. Results indicate that PG, TxA2, and histamine may be involved in the hypersensitivity reaction to BTV in cattle.     

Vitamin D status in cattle with malignant catarrhal fever

The aim of the present study was to determine the vitamin D status in cattle with malignant catarrhal fever (MCF). Twelve cattle diagnosed as MCF and 6 healthy cattle (controls) were used in the study. Serum 1,25-dihydroxyvitamin D(3) (1,25-D), 25-hydroxyvitamin D(3) (25-D), calcium, phosphorus and parathyroid hormone (PTH) levels were determined as 96.83 pg/ml, 30.0 ng/ml, 2.19 mmol/l, 1.57 mmol/l and 15.21 pg/ml in MCF group and 42.33 pg/ml, 37.0 ng/ml, 2.43 mmol/l, 1.96 mmol/l and 36.08 pg/ml in controls, respectively. Although serum 1,25-D level in the MCF group was increased (P<0.01), serum calcium (P<0.01) and PTH (P<0.05) levels were decreased compared to the controls. The results suggest that there might be an interaction between vitamin D status and MCF.     

Plasma concentrations of endothelin-like immunoreactivity in healthy horses and horses with naturally acquired gastrointestinal tract disorders

OBJECTIVE: To compare plasma endothelin (ET)- like immunoreactivity between healthy horses and those with naturally acquired gastrointestinal tract disorders. ANIMALS: 29 healthy horses and 142 horses with gastrointestinal tract disorders. PROCEDURE: Blood samples were collected from healthy horses and from horses with gastrointestinal tract disorders prior to treatment. Magnitude and duration of abnormal clinical signs were recorded, and clinical variables were assessed via thorough physical examinations. Plasma concentrations of ET-like immunoreactivity were measured by use of a radioimmunoassay for human endothelin-1, and CBC and plasma biochemical analyses were performed. RESULTS: Plasma ET-like immunoreactivity concentration was significantly increased in horses with gastrointestinal tract disorders, compared with healthy horses. Median plasma concentration of ET-like immunoreactivity was 1.80 pg/ml (range, 1.09 to 3.2 pg/ml) in healthy horses. Plasma ET-like immunoreactivity was greatest in horses with strangulating large-intestinal obstruction (median, 10.02 pg/ml; range, 3.8 to 22.62 pg/ml), peritonitis (9.19 pg/ml; 789 to 25.83 pg/ml), and enterocolitis (8.89 pg/mI; 6.30 to 18.36 pg/ml). Concentration of ET-like immunoreactivity was significantly associated with survival, PCV, and duration of signs of pain. However, correlations for associations with PCV and duration of pain were low. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with gastrointestinal tract disorders have increased plasma concentrations of ET-like immunoreactivity, compared with healthy horses. The greatest values were detected in horses with large-intestinal strangulating obstructions, peritonitis, and enterocolitis. This suggests a potential involvement of ET in the pathogenesis of certain gastrointestinal tract disorders in horses.     

Oestradiol stimulates the release of AVP and GnRH from the ewe hypothalamus in vitro.

Oestradiol (E(2)) sensitizes the stress and reproductive axes in vivo. Our current aim is to investigate whether E(2) directly influences hypothalamic AVP and GnRH release in vitro. Within 10 min of ewe killing, saggital midline hypothalamic slices (from the anterior preoptic area to mediobasal hypothalamus, 2 mm thick, two per sheep) were dissected, placed in oxygenated MEM-alpha at 4 degrees C and within next 2 h were singly perifused at 37 degrees C with oxygenated MEM-alpha (pH 7.4; flow rate 150 microl/min) alone (vehicle; n = 15), with low (6 pg/ml; n = 14) or high E(2) (24 pg/ml; n = 13). After 5 h equilibration, 10 min fractions were collected for 3 h with exposure to 100 mm KCl for 10 min within the last hour. Concentrations of AVP and GnRH were measured by RIA. Baselines for AVP and GnRH were 7.0 +/- 1.1 and 17.4 +/- 0.8 pg/ml respectively. Basal values with low E(2) were similar to vehicle for AVP (7.5 +/- 1.2 pg/ml) and GnRH (17.5 +/- 1.1 pg/ml). However, high E(2) increased basal AVP (11.7 +/- 1.4 pg/ml; p < 0.05) and GnRH (23.7 +/- 1.4 pg/ml; p < 0.05). After KCl, AVP and GnRH respectively, increased (p < 0.05) to 25.6 +/- 7.5 and 38.2 +/- 5.6 (vehicle), 26.3 +/- 7.5 and 23.6 +/- 2.1 (low E(2)) and 24.1 +/- 5.4 and 41.3 +/- 6.6 pg/ml (high E(2)). After KCl, maximum values of AVP occurred at 20 and GnRH at 30 min. In conclusion, high E(2) concentration augments AVP and GnRH release by direct action on the ewe hypothalamus.     

Correlation of pituitary histomorphometry with adrenocorticotrophic hormone response to domperidone administration in the diagnosis of equine pituitary pars intermedia dysfunction

Functional evaluation of the pars intermedia (PI) is required for the early diagnosis of equine pituitary PI dysfunction (PPID), yet most assays target the hypothalamic-pituitary-adrenal axis, which regulates the pars anterior. In contrast, the PI is regulated by dopaminergic tone from hypothalamic neurons. Loss of dopaminergic inhibition is hypothesized to cause the PI hypertrophy and hyperplasia that result in the clinical manifestations of PPID. Domperidone, a dopamine receptor antagonist, should exacerbate the loss of dopaminergic inhibition in horses with PPID and increase the release of endogenous adrenocorticotrophic hormone (eACTH) by PI melanotrophs. To test this, plasma eACTH concentration was determined in horses with or without clinical signs of PPID at 0, 4, and 8 hours after oral administration of 3.3 mg domperidone/kg. Pituitary glands were evaluated postmortem by histologic grading and morphometry. In the 33 horses, median age, plasma ACTH concentration 8 hours after domperidone, and PI area in median sagittal sections were associated with histologic grade as follows: pituitary grade 1 (normal), n = 3, 7.5 years, 20.0 pg/ml, 0.16 cm(2); grade 2 (focal hypertrophy or hyperplasia), n = 9, 14.5 years, 27.1 pg/ml, 0.27 cm(2); grade 3 (diffuse adenomatous hyperplasia), n = 5, 21.0 years, 64.4 pg/ml, 0.48 cm(2); grade 4 (microadenomas), n = 12, 23.3 years, 128.0 pg/ml, 0.87 cm(2); grade 5 (adenoma), n = 4, 24.9 years, 720.5 pg/ml, 2.1 cm(2). Results suggest that horses with pituitary histologic grade > or =3 respond to domperidone with increased plasma ACTH concentration.     

The effects of different photoperiods on reproduction in the sow

Three groups of Yorkshire sows (total of 106) were exposed to photoperiods of light:dark (LD) 24:0, 12:12 and 0:24, respectively, from d 1 postweaning to 24 h postestrus. The onset and duration of estrus, conception rate, farrowing rate and litter size were recorded. Serum concentrations of luteinizing hormone (LH), estrogen and progesterone were measured. Sows in the LD 24:0 exhibited behavioral estrus for a longer period (P less than .0001) than those in LD 12:12 (4.0 vs 2.7 d). The number of days to estrus from d 1 postweaning (5.4, 4.5 and 4.7 d, respectively), conception rate (60, 67 and 73%, respectively), farrowing rate (60, 67 and 73%, respectively) and litter size (10.6, 10.2 and 10.8, respectively) were not different (P greater than .05) for the three light regimens of 24:0, 12:12 and 0:24. Maximum serum levels of LH (5.4, 5.0 and 4.5 ng/ml, respectively) and estrogen (71.8, 63.3 and 60.4 pg/ml, respectively) were not different, nor were progesterone profile means (P greater than .05) for the sows in LD 24:0, 12:12 and 0:24. These data suggest that long photoperiods prolong manifestations of behavioral estrus in the sow.     

A role for the adrenal cortex in the onset of cystic ovarian follicles in the sow.

The corticotrophin (ACTH)-adrenal cortical axis has previously been implicated in the onset of cystic ovaries in the sow. In view of the role of the ACTH-adrenal cortical axis in stress, two sows were subjected to an elevated environmental temperature of 32 degrees C for three hours daily during the follicular phase of the estrous cycle. Plasma concentrations of glucocorticosteroids and progesterone fluctuated markedly in one sow that developed cystic ovaries. Concentrations of these hormones did not vary greatly in the other sow that did not develop cystic follicles. Exposure to an environmental temperature of 32 degrees C for three hours or injection of 1 IU/kg bodyweight of ACTH for each of two ovariectomized sows resulted in an elevation in progesterone values to 5-7 ng/ml plasma from basal levels of 1-2 ng/ml and a rise in total glucocorticosteroids from basal levels of 1 or 2 microgram/100 ml plasma to 4-10 microgram/100 ml. Injection of 2 mg/kg bodyweight of progesterone and 4 mg/kg bodyweight of cortisol into the ovariectomized sows was found to approximate these elevations in plasma steroid values. When either progesterone or cortisol was injected daily during the follicular phase into two intact sows in two successive experiments at these dosage levels, similarly elevated plasma steroid concentrations were seen and cystic ovarian follicles resulted. The results suggest that glucocorticosteroids and progesterone of adrenal origin may be involved in the onset of cystic ovaries in the sow.     

Therapeutic effect of aromatase inhibitor in two azoospermic dogs with high plasma estradiol-17beta levels

Two azoospermic dogs with high plasma estradiol-17 beta (E(2)) levels were subcutaneously injected with an aromatase inhibitor (AI), 4-androstene-4-ol-3,17-dione, 2 mg every other day for 4 weeks. Before the AI treatment the plasma E(2) levels of the two dogs (21 and 22 pg/ml, respectively) were higher than those of 2 normal dogs (8.1 and 12.3 pg/ml), and they fell to 11-17 pg/ml between 1 and 4 weeks after the start of AI treatment. The plasma testosterone levels after the start of AI treatment had increased to 2.1-3.1 ng/ml. A small number of sperm were detected in the semen of the two dogs between 3 and 6 weeks after the start of AI treatment. These results indicate that the testicular function of infertile dogs with high plasma E(2) levels can be temporarily improved by AI therapy.