规模舍饲山羊的主要繁殖性能

文章对盐亭汇源牧业有限责任公司种羊场2002～2005年山羊的繁殖生产记录资料和部分质量性状进行了统计分析.结果表明,在舍饲条件下,山羊全年均可发情,但配种季节主要集中在春、秋两季,尤以秋季最为集中;使用人工授精技术的受胎率达到自然发情配种母羊的受胎率;产单羔母羊的妊娠期极显著和显著地长于产双羔和三羔的母羊;不论公、母,单羔的平均初生重极显著高于双羔和三羔;出生双羔公羊的初生重显著高于三羔,双羔和三羔母羊的初生重无显著差异;窝产单羔和双羔时,公、母羔的初生重差异极显著,而窝产三羔时,公、母羔的初生重无显著差异;有胡须母羊的平均窝产羔数比无胡须母羊的平均窝产羔数高8.26%,无角母羊的平均窝产羔数比有角母羊的平均窝产羔数高5.70%,有肉髯母羊的窝产羔数高于肉髯母羊.     

河南大尾寒羊繁殖性能的观察与统计分析

对河南大尾寒羊繁殖性能进行了观察与统计分析。大尾寒羊母羊初配月龄约为8月龄。1~8胎次平均产羔率为249.27%,总的单羔率、双羔率、三羔率、四羔率及五羔率分别为8.00%、47.82%、36.36%、6.55%和3.27%。产双羔的母羊比率极显著高于产单羔、四羔和五羔的母羊比率(P<0.01);产三羔的母羊比率极显著高于产五羔的母羊比率(P<0.01)、显著高于产单羔及四羔母羊比率(P<0.05)。1~6胎产羔率总的趋势是随着胎次的增加而上升,7~8胎逐渐降低。胎产羔数与胎次回归方程的决定系数为R2=0.991 2。据回归方程计算了每胎的产羔估计值,并以5、6胎校正产羔值的简单平均数为基准计算了各胎次的校正系数。胎产羔数对初生重、断奶体重有显著或极显著的影响(P<0.05或P<0.01),随胎产羔数的增加,初生重和断奶体重减小。     

晋岚绒山羊多胎性能4个候选基因的研究

为探寻辅助育种的分子标记,提高绒山羊产羔数,本实验在山西省某绒山羊养殖场分别选取20只经产双羔母羊和单羔母羊,检测多胎性能候选基因GDF9、BMP15、FSHβ和GnRHR所有编码区SNPs位点;选取有差异的基因位点在171只经产母羊(90只双羔母羊和81只单羔母羊)中进行SNPs位点检测,统计基因型频率、等位基因频率、多态信息含量(PIC)和期望杂合度(He),并与母羊产羔数进行关联分析。结果显示:共发现17个SNPs位点,仅GDF9基因A959C位点和BMP15基因G735A位点在单、双羔母羊间有差异。SNaPshot检测表明GDF9基因A959C位点有AA、AC、CC 3种基因型,A为优势等位基因,AA为优势基因型,含CC、AC基因型个体的产羔数显著高于AA型。BMP15基因G735A位点共检测到GG、AG、AA 3种基因型,G为优势等位基因,GG为优势基因型;含AA、AG基因型个体的产羔数显著高于GG型。本研究结果表明GDF9基因A959C位点C等位基因和BMP15基因G735A位点A等位基因与晋岚绒山羊高产羔数呈极显著正相关,可作为分子标记对晋岚绒山羊进行辅助育种。     

特克塞尔羊和无角陶赛特羊在甘肃榆中地区繁殖性能的观察与统计分析

通过对特克塞尔羊和无角陶赛特羊在甘肃榆中地区的繁殖性能进行统计分析,发现两种羊的妊娠期分别为:149.71 d和149.18d,与国内肉羊的平均妊娠期150d相比,差异不显著(P＞0.05);两种羊的平均产羔率均较高,分别为132％和133％;特克塞尔羊和无角陶赛特羊单羔初生重极显著高于双羔初生重(P＜0.01);不同性别之间,公羊初生重极显著高于母羊(P＜0.01),同性别之间,特克塞尔羊单羔公、母羊初生重极显著高于双羔公、母羊初生重(P＜0.01),无角陶赛特羊单羔母羊显著高于双羔母羊(P＜0.05),单羔公羊初生重高于双羔母羊,但差异不显著(P＞0.05).表明两个品种的羊在甘肃榆中地区具有良好繁殖性能.     

陕北白绒山羊10月龄母羊发情周期血清激素分泌规律的研究

本实验旨在分析陕北白绒山羊10月龄母羊发情周期内卵泡刺激素(FSH)、黄体生成素(LH)、雌二醇(E_2)和孕酮(P_4)的含量变化规律,为研究幼龄陕北白绒山羊母羊的繁殖性能和生殖激素的调控提供理论依据。在一个发情周期内,连续20 d每天对8只10月龄陕北白绒山羊母羊进行颈静脉采血(母羊出现发情表现记为发情第0天);在发情期当天和发情间期第5天,从08:00开始,每间隔15 min连续采血3 h,分离血清,用酶联免疫测定法(ELISA)测定发情期、间情期和发情周期血清中FSH、LH、E_2和P_4的含量。结果表明:在发情期和间情期连续3 h内,FSH、LH、E_2和P_4均呈波动式分泌,FSH发情期比间情期波动频率快。LH发情期较间情期的波动频率低;在发情期血清内E_2含量较间情期高(P0.05);间情期血清内P4含量显著高于发情期(P0.05);在测定的20 d内,FSH、LH、E2血清中浓度值差异不显著(P0.05),而P4浓度在发情当日和发情次日低于发情间期(P0.05)。     

提高凉山半细毛羊产羔率选育技术的研究

用出生于双羔和三羔的公羊与出生于双羔或产过双羔的母羊选配，平均产羔率分别达到１１８．５２％、１２３．０８％和１２７．２７％。比出生于单羔的公、母羊交配的产羔率提高１２．６￣２６．７４个百分点。血液蛋白多态性电泳分析结果表明，出生于双羔的母羊血红蛋白Ｈｂ＾Ｂ型基因频率显著大于出生于单羔的母羊。血红蛋白基因型可以作为早期选择产羔率的辅助选择性状。     

巴美肉羊发情期血清FSH和LH浓度变化规律及其与产羔数关系分析

为了研究巴美肉羊血清生殖激素的动态变化及其与产羔数的关系,试验采用电化学发光免疫测定法分别测定了产单、双羔母羊发情期血清中2种促性腺激素(FSH和LH)的浓度,分析其动态变化规律,并用SAS9.0的方差分析程序分析激素浓度与产羔数的关系。结果表明:血清中FSH和LH均呈脉冲式分泌,单、双羔母羊FSH在发情后的1小时都出现1个峰值(P0.001),LH在发情后的12~24 h出现峰值;经方差分析,双羔羊FSH水平在发情后1小时极显著高于单羔羊(P0.001),12小时显著高于单羔羊(P0.05);双羔羊LH水平在发情后12小时极显著高于单羔羊(P0.001),24小时显著高于单羔羊(P0.05)。说明巴美肉羊产羔数增加与血清FSH和LH浓度升高有关。     

杜泊羊胚胎移植试验

48只杜泊绵羊供体用促卵泡素(FSH) 进行超排处理, 用手术法采胚, 39只羊共获250枚可用胚, 头均获可用胚为6 41 ( 250 /39 ) 枚,不同产地FSH及供体年龄对超排效果影响差异不显著(P>0 05)。将250枚可用胚植入209只小尾寒羊受体中, 产羔101只, 产双羔受体10只,产羔率为48 33% (101 /209)。结果表明: 移三胚、双胚的受体羊产羔率明显高于移单胚的产羔率, 差异极显著(P<0 01 ); 移植受体的移入侧卵巢上有3个及以上黄体的受胎率高于1个黄体和2个黄体, 但差异不显著(P>0 05); 不同饲养管理水平下羔羊初生重差异显著(P<0 05 ),但受胎率无显著差异。双羔平均初生重较单羔低0 58kg, 差异显著(P<0 05); 双羔成活率较单羔成活率低25 6%, 差异极显著(P<0 01 );单羔妊娠期较双羔长, 差异显著(P<0 05)。     

孕前补饲对山羊繁殖性能的影响

选择健康、空怀、经产、膘情中等以上的母羊分为两组(试验组70只,对照组52只),比较孕前补饲对山羊受胎率、产羔率、初生重、羔羊成活率等繁殖性状的具体影响程度.结果发现试验组与对照组母羊产单羔和双羔的百分率差异不显著,产多羔的母羊比对照组高4.3%;母羊受胎率差异不显著;羔羊死亡率比对照组下降16.9%;产单羔的初生重差异不显著,双羔的初生重比对照组高0.14 kg,差异极显著(P＜0.01).在配种前搞好放牧抓膘和补饲,实行满膘配种,是提高母羊繁殖性能的重要措施.     

FSHR基因多态性及其与陇东绒山羊产双羔关联性分析

为了寻找控制陇东绒山羊双羔性状的分子标记,本研究以陇东绒山羊双羔母羊及所产F1代为实验材料,并以单胎的陇东绒山羊母羊和单胎的辽宁绒山羊母羊为对照,采用PCR-SSCP及测序法分析陇东绒山羊FSHR基因第10外显子遗传多态性,运用最小二乘法分析其与产羔性状的关联性。结果检测到G1542T和T1595G2个多态位点,其中T1595G位点为错义突变,可导致所编码的氨基酸由甲硫氨酸(Met)变为精氨酸(Arg),该位点包括4种基因型分别为AA型、AB型、BB型和AC型,陇东绒山羊双羔群体的优势基因型为BB型,优势等位基因为B;陇东绒山羊BB型个体的产羔数最高,AB型个体次之,且AB型、BB型母羊产羔数与AA型、AC型差异显著。因此,FSHR基因第10外显子T1595G位点B等位基因对陇东绒山羊产羔数有显著影响,可以作为陇东绒山羊产双羔的一个候选分子标记。本研究为进一步筛选陇东绒山羊双羔性状主效基因提供了技术支撑,进而为加快高繁殖力陇东绒山羊的选育进程提供依据。     

莱芜黑山羊发情周期中FSH、LH、E2和P的分泌规律

莱芜黑山羊在发情期和间情期，血浆内的卵泡刺激素（FSH）和黄体生成素（LH）均呈脉冲式分泌，雌激素（E2）和孕嗣（P）为波动式分泌。发情期FSH的脉冲周期较间情期长，两者之间显著差异（P〈0．05）。发情期LH的脉冲周期短于间情期，两者之间差异不显著（P〉0．05）。在整个发情周期中，FSH和LH均先后出现4个分泌峰，FSH和LH的第1个分泌峰分别出现在第7天和第5天，其余3个分泌峰均同时出现（分别为第10、15和20天）。E2和FSH、LH均在发情周期的第20天迭最高峰。P在间情期一直维持在一个较高水平。     

Effects of supplementing with calcium salts of palm oil fatty acids or hydrogenated tallow on ewe milk production and twin lamb growth

Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.     

Changes in Plasma Concentrations of LH, FSH, Estradiol 17-β and Progesterone During Oestrus in Mithun (Bos frontalis)

The objective of the present study was to establish the changes in plasma concentrations of LH, FSH, estradiol 17-beta (E2) and progesterone (P4), as well as to understand their temporal relationships during oestrus in mithun (Bos frontalis). The experiment was conducted on 11 mithuns during third or fourth postpartum oestrous cycle. Since oestrus onset the jugular vein blood samples were collected every 2 h for 72 and 96 h, respectively from the animals without and with standing heat. The LH, FSH, E2 and P4 concentrations were estimated in plasma. The P4 concentration was fluctuated throughout the oestrus period and the average P4 concentration was found significantly (p<0.05) lower on the day of oestrus onset. The multiple rises in LH and FSH concentrations above the basal level in spike like fashion were observed throughout the oestrus period irrespective of the occurrence of standing heat. A significant (p<0.01) gradual increase in the average daily E2 concentration was observed till day 2 following oestrus onset irrespective of the occurrence of standing heat. A significant (p<0.05) simultaneous increase in LH, FSH and E2 concentrations and a transient increase in P4 concentration at approximately the time of standing heat onset were observed. During investigation a definite temporal coupling between LH and FSH rises was absent throughout the oestrus period. The results suggest that (1) the multiple short-duration low-amplitude LH and FSH surges during oestrus may be crucial for the final maturation of ovulatory follicle and subsequent ovulation in mithun; (2) a differential mechanism for controlling LH and FSH secretions probably exists in mithun.     

不同月龄绵羔羊卵泡发育的比较研究

本研究旨在比较1、3月龄绵羔羊激素处理后卵巢、子宫及血液中促卵泡激素(FSH)变化,研究不同月龄对羔羊卵泡发育的影响。通过对1、3月龄羔羊进行FSH和孕马血清促性腺激素(PMSG)处理,比较羔羊在激素处理前后血液中FSH水平和卵巢、子宫大小变化,卵巢上2～8 mm卵泡的数量和卵母细胞体外成熟、受精后胚胎的发育情况。结果表明:1月龄羔羊实验组体内整体FSH水平高于3月龄羔羊(P<0.05)。1月龄羔羊注射外源激素后两侧卵巢可获卵母细胞数(42.3±2.5、36.8±1.1)枚及体外受精囊胚发育率(16.33%±0.96%)显著高于3月龄羔羊卵母细胞数(10.0±0.7、8.5±0.6)枚及囊胚率(9.29%±1.55%)(P<0.05)。羔羊进行超数排卵处理时卵巢上卵泡发育与血液中FSH水平密切相关,且较高的FSH水平预示着较多的卵泡发育。     

Lactation curves of commercial ewes rearing lambs

Three-hour milk production measurements determined by machine milking at 3-d intervals throughout a 63-d lactation period were used to describe lactation curves for crossbred ewes lambing at 1 and 2 yr of age and rearing single and twin lambs. Age of ewe, type of rearing, and day of lactation affected (P < 0.05) milk production. Over the 63-d lactation, average daily milk production was 2.56 and 2.63 kg, respectively, for 1- and 2-yr-old ewes rearing single lambs and 2.73 and 3.47 kg, respectively, for 1- and 2-yr-old ewes rearing twins. Milk production of 2-yr-old ewes rearing twin lambs peaked at 21 d of lactation, and that of 1- and 2-yr-old ewes rearing singles peaked between 27 and 30 d of lactation. The largest differences in the lactation curves among age and rearing ewe classes were found in early lactation. These differences were reduced by midlactation, and by late lactation, milk production for all ewes was similar. Diurnal variation in milk production by ewes was evaluated in an 8 x 8 Latin square design. Diurnal variation in milk yield measurements of eight mature ewes, each bearing and rearing twin lambs, was similar between d 21 and 24 of lactation. Time of milk production measurements within a day did not affect yield determinations. Extrapolation from 3-h production estimates to daily milk production is valid in determining a ewe's milk contribution in support of lamb growth.     

Endocrine Profiles and Embryo Quality in Japanese Black Cattle Superovulated with Human Menopausal Gonadotrophin and Porcine Follicle Stimulating Hormone

Induction of superovulation using human menopausal gonadotriphin (hMG) in Japanese Black cattle can result in the recovery of a higher percentage of high quality embryos compared with that using porcine follicle stimulating hormone (FSH). In order to clarify the endocrinological mechanism involved in this discrepancy, 30 superovulation sessions of 17 Japanese Black cattle were studied. Fifteen cattle were super‐stimulated with hMG (total 600 IU), and the remaining 15 cattle were given FSH (total 20 mg). The plasma profiles of LH, estradiol‐17β (E₂) and progesterone (P₄) were correlated, and the embryo quality was investigated. The total number of ova recovered and the number of transferable embryos tended to be larger in the hMG‐treated group than in the FSH‐treated group. The percentage of excellent embryos tended to be higher in the hMG‐treated group than in the FSH‐treated group (54.3 and 28.7%, respectively, p < 0.10). The E₂ level increased during the first 3 days after the initial administration of either hMG or FSH and was higher in the hMG‐treated group than in the FSH‐treated group (p < 0.05). During this period, the E₂ level could be categorized into one of the following three types according to whether it increased or decreased and according to the degree of increase or decrease: (1) increase by a factor of 1.2 or more (quick increase type) (2) slight increase by a factor less than 1.2 (slow increase type), and (3) no increase (unstable increase type). In the group treated with hMG, 66.7% of the animals (10 of 15 cattle) showed a quick increase in the E₂ level. However, in the FSH‐treated group, 40% (six of 15) of the animals showed a slow increase in the E₂ level. The plasma LH level increased dramatically 8 h prior to the peak level in both the hMG‐ and FSH‐treated groups, and then it returned to the basal level 12 h later. After the administration of prostaglandin (PG)F_2α, the LH peak level was attained within 44 h in 80% of the animals in the hMG‐treated group, whereas in the FSH‐treated group, the LH peak level tended to be reached later. The P₄ level did not increase during the period of hMG or FSH treatment and decreased drastically following administration of PGF_2α. After the onset of oestrus, the P₄ level was higher in the hMG group than in the FSH group, and 5 to 7 days after oestrus, the level remained higher in the hMG group than in the FSH group (p < 0.05). After the first 3 days of hMG administration, the E₂/P₄ ratio was higher than that after FSH administration. Furthermore, on the day following PGF_2α administration, the ratio was significantly higher in the hMG group than in the FSH group (p < 0.05). These results indicate that superovulation in cattle given hMG results in a significant increase in plasma E₂ during the first 3 days and that the increase in the plasma P₄ level is larger a few days after oestrus and thereafter compared with FSH‐induced superovulation. Therefore, such plasma level profiles may be related to the increased recovery rate of high quality embryos.     

The effect of ewe maternal behaviour score on lamb and litter survival

The study was carried out on a commercial New Zealand sheep farm with high ewe reproductive rates and lamb survival produced through intensive selection in its Coopworth flock for maternal ability.Heritability and repeatability estimates were derived for ewe maternal behaviour score (MBS) and litter survival (LIS). Heritability estimates were derived for lamb survival as a trait of the lamb (LAS) for all lambs, for twin (LAS2) and for triplet (LAS3) lambs.MBS and LIS were measured on 1954 dams, for a maximum of four parities: 1997, 1998, 1999 and 2000. MBS was measured at tagging on a 5-point scale (1=poor, 5=excellent) when the dam's lambs were between 12 and 36 h old. The mean MBS in this study was 3.3 and increased with litter size. LIS was measured from birth to weaning. Mean litter survival was 83%. LIS increased significantly as MBS increased (P<0.01). LIS decreased as the size of the litter increased (P<0.01). Age of dam was a nonsignificant effect on LIS (P>0.05).LAS was measured from birth to weaning on 4171 Coopworth lambs. Mean LAS was higher for lambs born as twins compared to lambs born as singles and lowest for lambs born as triplets (P<0.01). LAS was lower for lambs born to dams aged 2 years. This effect was significant for all lambs, regardless of litter size at birth and for the triplet lamb data set (P<0.01). The effects of age of dam and sex of lamb on twin lamb survival were not significant (P>0.05). Ewe lamb survival rate was higher when compared to ram lambs in the full data set, however the relationship was reversed for the triplet lamb data set where ram lamb survival was greatest (P<0.01). LAS decreased as the MBS of its dam increased (P<0.01). The relationship was significant for lambs in the full data set and the twin data set (P<0.05).MBS and LIS were under minimal genetic control. The heritability and repeatability for MBS were both 0.09. The heritability and repeatability for dam LIS were 0.0 and 0.11. Heritability for LAS over all lambs attributed to direct effects was 0.14, while the heritability attributed to maternal effects was 0.11. The heritability for twin (LAS2) and triplet (LAS3) lamb survival differed. Heritability attributed to direct and maternal effects were 0.0 and 0.21, respectively, for twin lambs and 0.08 and 0.16, respectively, for triplets.The genetic correlation between maternal and direct effect for LAS was −0.74. It is possible that the genes that regulate physiological and biochemical processes for survival are incompatible with the genes that enhance ewe-lamb bonding. For example, the genes that regulate the physiological factors to reduce gregariousness at parturition may in fact be the same genes that encourage isolation in the neonate from its littermates and dam.There is minimal genetic variation in this flock for lamb survival and maternal traits. Low genetic variation suggests that selection will be ineffective, and that farmers must consider environment and management techniques for improving lamb survival.     

Evaluating the effect of calcium,magnesium and sodium supplementation of Merino ewes on their lambs' growth

Our study aimed to investigate responses to supplementation of calcium (Ca), magnesium (Mg) and sodium (Na) to lactating ewes and lambs grazing barley forage from lamb marking to weaning. A 10-ha paddock sown to barley was subdivided into eight plots as four replicates of two treatments. Merino ewes (n = 104) with lambs at foot were stratified to the eight plots (13 ewes and 21 lambs/plot) based on number of lambs (twin or single) and ewes' weight. Supplemented groups had access to mineral supplements (30 g/ewe/day) supplying 12 g/ewe/day ground limestone, 12 g/ewe/day Causmag® and 6 g/ewe/day coarse salt in a ratio of 2: 2: 1 by weight (as fed) from day 0 (a day before lamb marking) after sample collection. Control groups were not supplemented with minerals. Blood, milk and urine samples from ewes and blood from lambs were collected at different time points, namely, a day prior to lamb marking (day 0), 14 days after the commencement of study (day 14), and 28 days after the commencement of study (day 28). Weight of the lambs was also recorded at each time point. We found that the concentration of the forage minerals (Ca, Mg and potassium (K)) was lower on day 28 than on day 0 (P < 0.025). Liveweight gain was greater in the first 14 days compared with the second weight gain period (P < 0.001). The interaction of time and treatment was significant for liveweight (P < 0.001). Due to the improvement in weight gain of supplemented lambs, we recommend that mineral supplementation during late lactation is beneficial considering the low cost of minerals, even though the mineral content of the forage was not deficient.     

Multiple Factors Affecting Superovulation in Poll Dorset in China

To expand the breeding flock of Poll Dorset sheep in China, multiple ovulation and embryo transfer breeding program was applied to the limited number of imported Australian Poll Dorset sheep. This study investigated the effects of FSH from three different manufacturers, parity (nulliparous vs multiparous), repeated superovulation, oestrus induction, corpus luteum regression and oestrus delay on Poll Dorset superovulation. The results showed that gonadotropin FSH from Canada Folltropin‐V (Ca‐FSH) was successfully used for superovulatory treatment with 160 mg–200 mg dosage per ewe and recovered 12.91 ± 7.80 embryos. Multiparous ewes for superovulation treatment were significantly better nulliparous ewes (p < 0.05). The successive superovalution treatment reduced significantly embryo collection but did not affect transferable embryo number. Ewes with natural oestrus resulted in significantly higher number of embryos (13.83 ± 4.64) and of transferable embryos (12.00 ± 5.76) than ewes with induced oestrus (7.00 ± 4.92; 4.22 ± 3.42) and unknown oestrus cycle (5.94 ± 3.38; 3.19 ± 2.56, p < 0.05). The delayed oestrus ewes at 24 h after superovulatory treatment produced significantly fewer embryos and transferable embryos (0.92 ± 1.51 vs 0.42 ± 0.90) than those with normal oestrus (p < 0.01). Furthermore, the more transferable embryos were recovered from ewes with normal corpus luteum than those with corpus luteum regression (5.88 ± 5.09 vs 3.59 ± 4.30 and 8.83 ± 5.75 vs. 6.66 ± 5.41, p < 0.01). These results suggest that in our farm practice, a comprehensive treatment method by using the Canadian FSH (Folltropin‐V), plus choosing multiparous and natural oestrus ewes with normal corpus luteum might obtain an optimum embryo collection and embryos transfer in sheep.     

Leptin concentrations in periparturient ewes and their subsequent offspring

Leptin is an adipocyte-derived hormone that suppresses feed intake and increases energy expenditure. Leptin is also involved in regulating body temperature. Thus, the presence of leptin in milk, which can be absorbed through the gut of neonates immediately after birth, may aid in the survival of neonates born in cold weather. Our objectives were to determine the temporal relationship between concentrations of leptin in postpartum ewe blood serum and ewe milk serum, and to determine whether ewe blood and milk serum leptin concentrations were correlated with concentrations of leptin in lamb blood serum in their off-spring. Approximately 1 wk before the expected date of lambing, blood samples, weights, and body condition scores (BCS; 0 to 5 scale) were collected from 27 mixed-parity ewes. Following parturition, ewe blood and milk samples were collected within 2 h of parturition (d 0), 12 h (d 0.5) and 24 h (d 1) after parturition, again on d 5, and weekly thereafter until d 47. Lambs were blood-sampled and weighed within 2 h of parturition (d 0), bled daily until d 5, and bled and weighed weekly thereafter to d 47. Prior to lambing, ewe blood serum leptin was positively correlated with congruent BCS (r2 = 0, 10, P = 0.06), but not weight (P = 0.14). Following parturition, ewe blood serum leptin was positively correlated with BCS, weight, and milk serum leptin (r2 = 0.14, P < 0.0001, r2 = 0.12, P < 0.0001, and r2 = 0.028, P = 0.04). Leptin in milk serum was correlated with ewe weight (r2=0.05, P = 0.007) but not ewe BCS (P = 0.7); however, concentrations of leptin in both ewe blood and milk serum varied with day of lactation (P = 0.0001), being maximal within 24 h of parturition and declining to nadir concentrations by d 5. Leptin in lamb serum was correlated with milk serum leptin, (r2 = -0.05; P = 0.001), but not ewe blood serum leptin (P = 0.5). Concentrations of leptin in lamb serum increased from birth to d 5 and declined thereafter to nadir concentrations by d 19. Elevated concentrations of leptin in milk during the early stages of lactation may provide a mechanism for thermoregulation, satiation, and homeostatic endocrine control in the neonate.