Correlations among antral follicular echotexture,apoptosis and expression of key steroidogenic enzymes in sheep

Nineteen cycling ewes underwent transrectal ultrasonography of ovaries followed by ovariectomies during the growth phase of the first follicular wave of the interovulatory interval or the proestrus/estrus phase of the cycle. Quantitative ultrasonographic characteristics of the antrum and follicular wall in a total of forty-three ovine antral follicles were examined for correlations with the protein expression of three steroidogenic enzymes (cytochrome P450 17α-hydroxylase, CYP17; cytochrome P450 aromatase, CYP19; and 3β-hydroxysteroid dehydrogenase, 3β-HSD) determined by densitometric analysis of immunohistochemical slides, follicular dimensions, granulosa layer thickness and the percentage of apoptotic granulosa cells. Significant correlations were found between echotextural attributes of ovine antral follicles and the percentage of apoptotic granulosa cells, CYP17 expression (theca), CYP19 expression (granulosa) and 3β-HSD expression (theca cells). Computer-aided analyses of ultrasonographic images can be beneficial to the development of assisted reproductive technologies and diagnosis of hormonal imbalances without the need for ovarian biopsies or hormone assays.     

The effect of antimicrobial growth promoter withdrawal on the health of weaned pigs in Finland

The use of the antimicrobial growth promoters (AGPs) carbadox and olaquindox has been banned in the European Union (EU) since September 1999. We studied the effects of the withdrawal on the health of weaned piglets on two types of piglet-producing farms (farrowing herds and farrow-to-finish herds) from the different regions of Finland. Farms with no major problems with post-weaning diarrhoea were selected for the study to better evaluate the effect of AGPs alone. Data on production, medication and incidence of diarrhoea were collected from 73 farms during 1 year after the withdrawal. On 29 of these farms, the data collection began 4 months before the withdrawal.

The health management of the pigs is considered good in Finland, and special attention has been paid to improve the husbandry practices and management of the farms. Eighty-two percent of the farms in the study were free of both Mycoplasma hyopneumoniae and Sarcoptes scabiei infection. Brachyspira hyodysenteriae infection was not detected in any of the farms. The median number of sows in the herds was 56.0 (IQR = 43.0; 72.5) in 2000.

The level of antimicrobial use in each herd was classified as low, moderate and high when the percentage of weaned pigs treated for diarrhoea during a 4-month period was 0–5%, 6–19% and ≥20%, respectively. Only on four herds (14%), there was an increase in the level of antibiotic use after the AGP withdrawal, when seasonally corresponding 4-month periods were compared. Fourty-one percent of these 29 farms were categorized as low users of antimicrobials, 38% as moderate users and 21% as high users.

The level of antimicrobial use for treatment of diarrhoea after weaning (and the incidence of diarrhoea in weaned piglets) did not increase significantly after the withdrawal of AGPs from weaner feeds according to farmers’ evaluations. In this study, the Escherichia coli infection was the most-common cause of diarrhoea in weaned pigs. The age at weaning did not change after the withdrawal of AGPs.     

Effect of dietary non-starch polysaccharide solubility and inclusion level on gut health and the risk of post weaning enteric disorders in newly weaned piglets

The objective of this experiment was to investigate the effect of non-starch polysaccharide (NSP) solubility and inclusion rate on gut health and development, performance and risk of post weaning enteric disorders (PWED) using NSP sources known not to affect digesta viscosity. The experiment consisted of a 2 × 3 factorial combination of NSP type (sNSP vs insoluble NSP (iNSP); inulin vs purified cellulose) and inclusion level (50 vs 100 vs 150 g/kg). Piglets were weaned at 28 days (day 0) and fed ad libitum until slaughter on day 14. There were no incidences of PWED. NSP solubility had little effect on performance, but sNSP diets resulted in lower caecal and colonic pH and higher colonic Lactobacilli to coliform ratio compared to iNSP diets. Increasing NSP levels significantly reduced caecal and colonic pH but decreased empty body weight percentage (P = 0.067). These results suggest that gut health may benefit most from diets containing appropriate sources of predominantly sNSP rather than iNSP. The optimal level of such sNSP will likely depend upon the level of risk of PWED in order to balance the trade off between maximising performance and improving gut health. Effects of NSP feeding under a higher infectious pressure remains to be assessed.     

Characteristic of duodenal myoelectric activity in relation to food in piglets during the 3rd and 4th week of life

The relationship between duodenal myoelectric activity and liquid food intake was investigated in eight conscious piglets with bipolar electrodes implanted on the wall of the duodenum. Piglets were fed with commercial milk formula and the effects of volume and feed dry matter intake on duodenal myoelectric activity were measured by means of an analog–digital recording system.The cyclic pattern of duodenal myoelectric activity, i.e. the migrating myoelectric complex (MMC), was preserved when piglets received small meals at regular intervals. The duration of the whole MMC cycle, as well as the duration of phase II of the MMC, were only weakly correlated (r = 0.2, P < 0.05 for both parameters, respectively) to the amount of ingested food. However, the increase of the amount of feed dry matter intake of a meal from 2.1 to 4.5 g kg^− 1 of live body mass (LBM) as well as an increase of volume of a meal from 13 to 26 ml kg^− 1 LBM significantly increased the duration of the MMC cycles (P < 0.05) due to the elongation of phase II of the MMC (P < 0.05).The present study shows that in piglets fed with a liquid diet the upper gut motility response to food is similar to that previously observed in adult animals.     

定时输精对母猪繁殖性能的影响

为了研究同期发情+定时输精对母猪发情率、妊娠率及产仔数的影响。试验1:将200头后备母猪随机分成两组,每组100头。所有后备母猪连续饲喂四烯雌酮(ATL)(15 mg/d)14 d,第15 d开始查情。试验组后备母猪停止饲喂ATL 24 h后肌注促性素(PMSG)、再过72 h肌注生源(Gn RH),肌注Gn RH 24 h后开始输精1次,过24 h再输精1次;对照组后备母猪停止饲喂四烯雌酮后有发情就开始输精,过24 h再输精1次(如还发情,第2次输精过24 h后再输精1次);试验2:将200头断奶母猪随机分成两组,每组100头,断奶第2 d开始查情。试验组断奶母猪断奶24 h后肌注促性素(PMSG),再过72 h肌注生源(Gn RH),肌注Gn RH 24 h进行输精1次,过24 h再输精1次;对照组断奶母猪发情就开始输精,过24 h再输精1次(如还发情,第2次输精过24 h后再输精1次);精液剂量为80 ml(2×109个精子细胞)。试验1结果显示,试验组的后备母猪的静立率(P>0.05)、妊娠率(P<0.05)、分娩率(P<0.05)、窝产仔数(P>0.05)均高于对照组。试验2结果显示,试验组的断奶母猪的发情率、妊娠率、分娩率均高于对照组(P>0.05),窝产仔数也高于对照组。试验结果表明,母猪肌注PMSG和Gn RH,可改善母猪的发情率、分娩率、窝产仔数,减少隐性发情母猪的漏配率。     

Relationship of fertility to ovarian follicular waves before breeding in dairy cows

Cows with two waves of follicular growth during the estrous cycle yield follicles that are older and larger at ovulation compared with cows having three waves. The objectives of the current research were 1) to compare fertility in cows with two or three follicular waves and 2) to examine associations between luteal function, follicular development, and fertility after breeding. Follicular waves were monitored by ultrasonography during the estrous cycle before insemination in 106 dairy cows. Fewer cows had three follicular waves before next estrus and ovulation than two waves (P < 0.01; 30% vs 68%, respectively), but pregnancy rate was higher (P = 0.058; 81 vs 63%, respectively). Cows with two waves had shorter estrous cycles (P < 0.01), with the ovulatory follicle being both larger (P < 0.05) and older (P < 0.01). In cows with three waves, luteal function was extended (P < 0.05) and the peak in plasma progesterone occurred later (P < 0.05) in the estrous cycle compared to two wave cows. Considering cows that became pregnant, luteal phase length was shorter (P < 0.05) during the estrous cycle preceding insemination than for nonpregnant cows. In conclusion, fertility was greater in lactating cows inseminated after ovulation of the third-wave follicle that had developed for fewer days of the estrous cycle as compared with two-wave cows.     

提高夏季断奶母猪发情率的几点措施

<正>广东省地处热带和亚热带季风气候区,每年夏季,平均气温为28～29℃,6～8月份最高气温达到36～38℃,且持续较久,给养猪生产带来极为不利的影响,表现为母猪发情率等生产指标明显下降。断奶母猪发情率,与其他月份相比往往下降20%～40%,甚至出现暗发情或发情状态很不稳定,造成配种后返情率很高,一定程度上困扰养猪生产。这可以从我场2008年全年一个单元内断奶母猪的发情率进行比较(见表1)。鉴于此,笔者从防暑降温工作落实、改善母猪膘情、改变查情时间等方面谈谈提高断奶母猪发情率的一些看法。     

Resynchronization of estrus in beef cattle: ovarian function, estrus and fertility following progestin treatment and treatments to synchronize ovarian follicular development and estrus

The objective was to optimize rebreeding of nonpregnant, previously inseminated beef cattle. In Experiment 1, 43 cows received a used intravaginal progesterone-releasing insert (IVPRI; Days 0-7) 12.3 d after ovulation and received concurrently no treatment, 100 microg gonadotropin releasing hormone (GnRH), 1 mg estradiol cypionate (ECP), or 150 mg progesterone. Emergence of a new ovarian follicular wave was most synchronous (P < 0.0001) in the GnRH group. In Experiment 2, 675 heifers were given GnRH or no treatment on Day 0, fed melengestrol acetate (MGA; 0.5 mg/head/d) from Days 0-5 (Day 0 = 13-14 d after timed insemination; TAI), given 0.5 mg ECP or nothing on Day 7, and reinseminated 6-12 h after onset of estrus. Estrus was more synchronous (P < 0.05) in heifers given GnRH versus no treatment on Day 0. In Experiment 3, 317 TAI heifers were resynchronized with either MGA or a used IVPRI with or without ECP on Day 7; estrus was more synchronous (P < 0.05) and pregnancy rates were higher (54.1% versus 39.2%, P < 0.05) in heifers given a used IVPRI than those fed MGA. For resynchronization of heifers, pregnancy rates were not significantly improved with GnRH treatment, but were higher with a used IVPRI than with MGA.     

加温饲养和定时饲喂对断奶仔猪肠黏膜形态和肠道发育的影响

试验旨在探索对仔猪床进行加温处理以及采用定时饲喂的方式的对早期断奶仔猪不同肠段黏膜形态和肠道发育的影响,从而为确定断奶仔猪适宜的饲养温度和科学的饲喂方式提供理论依据。试验采用2×2因子设计。选用21日龄杜长大断奶仔猪240头,随机分到4个处理组:1):28~30℃的仔猪床加温处理组;2)23~25℃的低温对照组(炉火暖气管道舍内加热);加温处理组和低温对照组中又根据不同的饲喂模式分为每天6次定时饲喂组和自由采食组。每个处理6个重复,每个重复10头猪。经过14 d的试验之后,在每圈仔猪中随机抽取1头,屠宰后取样检测小肠黏膜的绒毛高度、隐窝深度和肠壁厚度。结果表明:加温饲养组(28~30℃)的仔猪空肠中段的绒毛高度显著高于低温对照组(23~25℃)(P<0.05)。加温饲养组十二指肠的隐窝深度和空肠中段的肠壁厚度显著低于低温对照组(P<0.05)。定时饲喂饲养的仔猪空肠后段的绒毛高度显著高于自由采食饲养的仔猪(P<0.05)。定时饲喂组仔猪空肠中段的肠壁厚度和十二指肠隐窝深度显著低于自由采食组(P<0.05)。2因子的互作效应表明:加温定时饲喂组饲养的仔猪空肠后段的绒毛高度显著高于其他处理组。低温自由采食组饲养的仔猪空肠后段的绒毛高度极显著低于其他处理组(P<0.01)。加温定时饲喂组的仔猪空肠中段的肠壁厚度极显著低于其他处理组(P<0.01)。由结果可知,28~30℃的加温饲养组以及定时饲喂的饲喂模式有利于仔猪的肠道黏膜形态的改善,有益于肠道的发育和健康。     

Effect of weaning age and postweaning feeding programme on the growth performance of pigs to 10 weeks of age

This study aimed to determine the effects of weaning age and postweaning feeding programme on pig performance and health. In experiment 1, 96 same gender pairs of pigs weaned at 3, 4 and 5 weeks of age were used in a 3 (weaning age)×4 (dietary programme) factorial design experiment. Pigs received different amounts of a phase 1 diet (16.2 MJ/kg digestible energy (DE) and 16.2 g/kg lysine) and phase 2 diet (15.3 MJ/kg DE and 15.0 g/kg lysine): (A) very low (VL, 1 kg phase 1 and 3 kg phase 2 diet per pig); (B) low (L, 2 kg phase 1 and 6 kg phase 2 diet per pig); (C) medium (M, 3 kg phase 1 and 9 kg phase 2 diet per pig) or (D) high (H, 4 kg phase 1 and 12 kg phase 2 diet per pig), followed by a cereal based phase 3 diet (15.0 MJ/kg DE and 13.8 g/kg lysine) to 10 weeks of age. In experiment 2, faecal samples from 60 pigs weaned at 3, 4 and 5 weeks of age were collected at 10 days postweaning and analysed for Escherichia coli and lactic acid bacteria counts. In experiment 1, there were no interaction effects of age×dietary programme on growth performance. Dietary programme did not affect growth performance from weaning to 10 weeks of age. From weaning to 10 weeks of age, increasing weaning age increased average daily gain (ADG; 363, 402, and 476 g for 3, 4 and 5 weeks respectively; s.e. 17.6; P<0.001), average daily feed intake (ADFI; 560, 620, and 680 g; s.e. 26.1; P<0.001), and improved feed conversion ratio (FCR; 1.57, 1.55, and 1.43; s.e. 0.045; P<0.05). However, weaning age had no effect (P>0.05) on pig weight at 10 weeks of age. In experiment 2, 3 week weaned pigs had higher faecal counts of E. coli (P<0.05) than 4 week weaned pigs and higher faecal counts of lactic acid bacteria (P>0.01) than 5 week weaned pigs at 10 days postweaning. In conclusion, feeding higher amounts of phases 1 and 2 diets did not affect performance at any of the weaning ages tested. Increasing weaning age increased growth performance between weaning and 10 weeks of age, but had no effect on the resulting body weight. Pigs weaned at 3 weeks of age had increased counts of selected faecal bacteria compared to those weaned later.     

Effects of Acclimate™ on the frequency and duration of aggressive sequence and growth performance in co-mingled, weaned pigs

Co-mingling weaned pigs often results in aggressive behavior which can result in injury and reduced performance. This experiment examined the effect of Acclimate™, a product reported to reduce equine aggression, on weaned pig aggression and growth performance. Weanling pigs (n=214, avg. wt.=5.93 kg) were blocked by weight, sex and litter (n=25) and randomly assigned to either Acclimate™ treatment or a control group. Acclimate™ treated pigs were marked on the nose, face and neck. Pigs were individually identified and videotaped to determine frequency of aggressive sequence (FAS) and duration of aggression (DOA) on an individual pig basis. Pig weights and feed consumption were used to determine feed intake, total weight gain (TWG), average daily gain (ADG) and feed to gain ratio (F/G). Differences between litter, sex and treatment for FAS, DOA, F/G and ADG were tested using GLM, SAS. Neither Acclimate™ treatment or sex had a significant effect on FAS, TWG or F/G. However, there was a trend towards reduced duration and intensity of aggression in Acclimate™ treated pigs (p=0.1). There was a significant effect of litter (p<0.01) and TWG (p<0.001) on FAS at both 1 and 3 weeks. Acclimate™ treatment of weaned pigs does not decrease FAS, but may decrease the intensity and duration of aggression without negatively effecting growth.     

Expression and localization of adiponectin and its receptors in ovarian follicles during different stages of development and the modulatory effect of adiponectin on steroid production in water buffalo

Adiponectin is an adipocyte‐derived hormone regulating energy metabolism, insulin sensitivity and recently found to regulate reproduction. The current study was carried out to investigate gene and protein expression, immunolocalization of adiponectin and its receptors AdipoR1 and AdipoR2 in ovarian follicles of different developmental stages in water buffalo (Bubalus bubalis) and to investigate the effect of adiponectin on steroid production in cultured bubaline granulosa cells. qPCR, western blotting and immunohistochemistry were applied to demonstrate mRNA expression, protein expression and immunolocalization, respectively. The results indicate that adiponectin, AdipoR1 and AdipoR2 were present in granulosa cells (GC) and theca interna (TI) of ovarian follicles and the expression of adiponectin, AdipoR1, AdipoR2 in GC and AdipoR1 and AdipoR2 in TI increased with increase in follicle size (p < .05). Expression of adiponectin was high in small and medium size follicles in TI. The adiponectin and its receptors were immunolocalized in the cytoplasm of GC and TI cells. Further, in the in‐vitro study, GCs were cultured and treated with recombinant adiponectin each at 0, 1 and 10 µg/ml alone or with follicle stimulating hormone (FSH) at 30 ng/ml) or Insulin‐like growth factor I (IGF‐I) at 10 ng/ml for 48 hr after obtaining 75%–80%s confluency. Adiponectin at 10 µg/ml increased IGF‐I‐induced estradiol (E₂) and progesterone (P₄) secretion and FSH‐induced E₂ secretion from GC and also increased the abundance of factors involved in E₂ and P₄ production (cytochrome P45019A1 [CYP19A1] and 3‐beta‐hydroxysteroid dehydrogenase [3β‐HSD]). In conclusion, this study provides novel evidence for the presence of adiponectin and its receptors in ovarian follicles and modulatory role of adiponectin on steroid production in buffalo.     

Effects of oral caffeine administration to sows with induced parturition on hypoxia in piglets

To counteract the effects of perinatal hypoxia in piglets, the oral administration of caffeine to sows with induced parturition was evaluated. On day 113 of gestation 9 sows received 27 mg/kg body weight (BW) of caffeine mixed with 200 g of standard diet. The same amount of feed without the addition of caffeine was administered to 9 control sows. Additionally, on day 113 of gestation, all sows were treated by two injections in the perianal area of 1 mg of alfaprostol (at 8:00 am and 14:00 pm), and on the morning of farrowing by 14 IU of oxytocin in the perianal area. Caffeine did not affect BW of piglets and size of litters; however piglets from treated sows showed a higher capacity to adapt to extra-uterine life. Particularly, they showed a greater thermoregulatory ability (P<0.001) and a higher percentage of viability score≥7 compared to piglets from control sows (92% vs. 75%, respectively; P=0.030). Caffeine furthermore reduced the frequency of high serum biopterin values (>80 nmol/L) in piglets born from treated sows (P=0.001). In conclusion, the caffeine orally administered to sows with induced parturition showed a protective effect on the consequences of neonatal hypoxia in tissue ischemia–reperfusion injury in piglets.     

Changes in the ovary and the peripheral concentrations of sex hormones after the aspiration of follicular fluid from the spontaneous follicular cysts of dairy cows

The aim of the present study was to clarify the ovarian and hormonal dynamics after the aspiration of follicular fluid in cows with follicular cysts. Follicular fluid was aspirated from the follicular cysts and follicles that were fated to become cystic follicles and other coexisting normal follicles, respectively, in lactating cows (n = 3). After the aspiration procedure, new follicles developed and reached a diameter of 25 mm without ovulation within 13–19 days. The plasma concentrations of inhibin decreased and follicle-stimulating hormone increased rapidly after the aspiration procedure, and subsequently increased and decreased, respectively, as a new follicle grew. No luteal structures developed after the aspiration procedure, and the animals’ plasma progesterone levels remained low. The present study indicates that the cystic follicles are never luteinized by the aspiration of follicular fluid, and consequently, new follicular cysts are observed to repeatedly develop.     

Effects of hypercaloric diet-induced hyperinsulinemia and hyperlipidemia on the ovarian follicular development in mice

Long-term hypercaloric diets may adversely affect the development of ovarian follicles. We investigated the effects of high sugar (HS), high fat low sugar (HFLS), and high fat normal sugar (HFNS) diets on the ovarian follicle development in mice fed with these diets as compared to those fed with normal diet (control) for 180 days. Body weight, gonadal fat, glucose, lipid, insulin, estrous cycle, sex hormones and ovarian tissues were examined, and metabolism-related protein expression in the ovaries was evaluated by immunoblotting. The mice fed with hypercaloric diets showed hyperinsulinemia and hyperlipidemia, and exhibited heavier body and gonadal fat weights, longer estrous cycles, and fewer preantral and antral follicles than mice fed with normal diet. The sex hormone levels in the blood were similar to those in controls, except for significantly elevated estradiol levels in the HS diet group. The AMPKα phosphorylation was reduced, while AKT phosphorylation and caspase-3 levels were increased in the ovarian tissues of mice in all three hypercaloric diet groups than those in control. Taken together, the results suggest hyperinsulinemia and hyperlipidemia as possible mechanisms that impair the development of ovarian follicles in response to long-term exposure to unhealthy hypercaloric diets.     

Profitability of bovine somatotropin administration to increase first insemination conception rate in seasonal dairy herds with heat stress

A dairy farm simulation program was used to estimate the economic value of increased conception rate at first insemination (FCR) as a result of one administration of bovine somatotropin (BST) per lactation. Further, the economically optimal BST administration period in a year was investigated. Typical conditions in Florida were assumed, including reduced milk production and conception rates in the summer and early fall due to heat stress. Administration of a single dose of BST ($6 per dose) per lactation was incorporated into a timed AI protocol for first insemination at 61 days after calving. Increases in FCR of 0, 4, 8, and 12 percentage points (PP) were compared including changes in prices, fertility, and seasonality of cow performance. No direct effect of BST on milk production was assumed. With default inputs and an increase in FCR of 4 PP, the optimal administration period was February through June which resulted in a small gain in profitability of $0.80/slot/year. Typically, one administration of BST per lactation to increase FCR was profitable in the cooler winter and spring, but not the hotter season. The use of BST in the cooler winter and spring resulted in increased seasonality of herd performance and demographics. When no seasonality in milk production was assumed, administration of BST was profitable throughout the year when FCR increased at least 8 PP. In conclusion, increases in FCR were most profitable during the cooler season of the year when basic conception rates were already greater than in the hotter season.     

Dynamics of ovarian follicular development in cattle during the estrous cycle, early pregnancy and in response to PMSG

Ovarian follicular dynamics of cattle were examined during the estrous cycle, early pregnancy and in response to PMSG. Number and size of follicles were monitored by ultrasonographic examinations. During the estrous cycle, distinct periods of follicular dominance (measured by the increase in difference in size between the largest and second largest follicle) occurred in both the luteal (Days 6-8) and proestrus (18-22) phases of the estrous cycle (two follicular waves). Associated with the well timed development of the first dominant follicle was a change in distribution of follicle numbers in small (less than 5 mm; increased on Days 2-4), medium (6-8 mm; increased on Days 3-5) and large (greater than or equal to 9 mm; increased on Days 6-9) follicular size classes. Follicular development was greater on the ovary bearing the CL for the period that the CL was present. The dominant follicle formed during the first follicular wave was capable of ovulating (6 of 8 heifers) following an injection of a synthetic analogue of prostaglandin F-2 alpha on Day 9 of the estrous cycle. During early pregnancy (Days 6-34), follicular development (size of largest follicle, number of follicles and total accumulated size of all follicles) on the ovary bearing the CL was suppressed between Days 24 and 34 of pregnancy. This was a local effect in that follicular development was sustained on the contralateral ovary. Therefore, the CL or conceptus may be regulating follicular development in a manner to help prevent luteolysis. Associated with the injection of PMSG was an initial increase in the number of small follicles followed by their recruitment into medium and large size classes leading to ovulation. Number of follicles greater than 5 mm on the Day of estrus was related (r = .97) to the number of subsequent embryos and oocytes collected. Ultrasonography is a valuable technique to monitor ovarian follicular dynamics in cattle, and can thereby be used to infer changes in physiological and endocrine states.     

Investigation of a simplified artificial lighting programme to improve the fertility of sows in commercial piggeries

Two artificial lighting regimens were studied in a commercial unit of 800 sows. The aim was to develop a simplified lighting regimen to overdrive the effects of season on reproduction. A long-day group had a constant 16 hours light and eight hours dark photoperiod in all units during a production cycle. A short-day group had eight hours of light and 16 hours darkness in a farrowing unit for four weeks and in a mating unit for four weeks. After one month of pregnancy the short-day group was transferred to 16 hours light and eight hours dark for the rest of the dry-sow period. Production data were collected for eight months, and the farrowing rate, weaning to oestrus interval, culling rate for fertility problems and the number of live-born piglets were analysed. Seasonal infertility, which had previously affected the herd, was not detected in either group during the follow-up period. The farrowing rate was 90 per cent for both groups. The median weaning to oestrus interval was five days in both lighting regimens with ranges from four to 74 days in the short-day group and three to 55 days in the long-day group. The long-day programme had a positive effect on the weaning to oestrus interval. When the sows were classified as either "normal", with a weaning to oestrus interval of up to 10 days, or "problem" animals, with a weaning to oestrus interval of over 10 days, the short-day programme also had a positive effect. The culling rate for fertility problems was 2.4 per cent for the short-day group and 3.2 per cent for the long-day group (P=0.027). The only significant predictor for the number of live-born piglets was parity (P=0.027).     

6月龄和成年牦牛卵巢及卵泡发育状况研究

为了研究6月龄牦牛和成年牦牛卵巢及表面卵泡发育状况,试验比较了6月龄和成年牦牛卵巢长度、宽度、厚度、重量、卵泡数量以及卵母细胞体外成熟培养效果。结果表明:成年牦牛卵巢长度(2.29±0.43)cm、宽度(1.91±1.31)cm和厚度(1.60±1.90)cm均显著大于6月龄牦牛[(1.65±0.30)cm、(1.14±0.25)cm、(0.79±0.26)cm](P<0.05),成年牦牛卵巢体积(6.92±7.00)cm3和重量(3.19±1.58)g极显著大于6月龄牦牛体积(1.63±0.93)cm3和重量(0.87±0.44)g(P<0.01)。6月龄牦牛Ⅰ级卵泡数(14.47±8.74)枚和平均总卵泡数(15.17±8.87)枚极显著高于成年牦牛Ⅰ级卵泡数(7.97±3.72)枚和平均总卵泡数(8.98±3.87)枚(P<0.01),Ⅱ级卵泡数差异不显著(P>0.05),成年牦牛平均每头含(0.02±0.15)枚Ⅲ级卵泡,而6月龄牦牛无Ⅲ级卵泡。成年牦牛有黄体卵巢重量显著大于无黄体卵巢重量(P<0.05),有黄体卵巢含(0.06±0.24)枚Ⅲ级卵泡,而无黄体卵巢不含Ⅲ级卵泡。6月龄和成年牦牛A、B级卵母细胞体外培养成熟率分别为(81.39±3.53)%、(80.44±4.50)%,差异不显著(P>0.05),而6月龄牦牛卵巢的平均卵母细胞数和平均A、B级卵母细胞数均显著高于成年牦牛(P<0.05)。