Nutritionally induced relationships between insulin levels during the weaning-to-ovulation interval and reproductive characteristics in multiparous sows: I. Luteinizing hormone, follicle development, oestrus and ovulation

To get more insight in how insulin secretion patterns and corresponding insulin-like growth factor-1 (IGF-1) levels are related to luteinizing hormone (LH) secretion, follicle development and ovulation, 32 multiparous sows were fed either a dextrose plus lactose-containing diet at 4 h intervals (DL; each 150 g/day) or an isocaloric control diet at 12 h intervals (CTRL; containing soybean oil) during the weaning-to-ovulation interval (WOI). Insulin parameters (basal, peak levels and mean insulin) and IGF-1 levels during the WOI were similar for both treatments, but the insulin secretion pattern differed (related with feeding frequency and meal sizes). Oestrus and ovulation characteristics were not influenced by treatment. The LH surge was higher in CTRL compared with DL sows (3.73 vs 3.00 ng/ml; p = 0.03). Average diameter (6.5 vs 6.1 mm; p = 0.08) and uniformity (CV: 11 vs 15%, p = 0.02) of follicles ≥3 mm at day 4 after weaning was higher in CTRL compared with DL sows. Basal insulin levels were positively related with follicle diameter at ovulation (β = 0.05 mm/(μU/ml); p = 0.04) and negatively related with LH surge level (β = -0.07 (ng/ml)/(μU/ml); p = 0.01). Insulin area under the curve (AUC) (β = 0.037 (ng/ml)/1000 μU; p = 0.02) and IGF-1 levels (β = 0.002 (ng/ml)/(ng/ml); p < 0.01) were positively related to basal LH level around the LH surge. From these data, we conclude that insulin and IGF-1 levels during the WOI are related to LH secretion and follicle development. Not only the absolute level of insulin seems important, but also the pattern within a day in which insulin is secreted seems to affect LH secretion and development of pre-ovulatory follicles.     

Natriuretic peptide system regulation in granulosa cells during follicle deviation and ovulation in cattle

Natriuretic peptides (NPs) are known to regulate reproductive events in polyovulatory species, but their function and regulation in monovulatory species remain to be fully characterized. Using a well‐established in vivo model, we found that bovine granulosa cells from follicles near the deviation stage express mRNA for the three NP receptors (NPR1, NPR2 and NPR3), but not for NP precursors (NPPA, NPPB and NPPC). The abundance of NPR3 mRNA was higher in dominant compared to subordinate follicles at the expected time of follicular deviation. After deviation, mRNA for all NP receptors was significantly more abundant in the dominant follicle. Intrafollicular inhibition of oestrogen receptors downregulated NPR1 mRNA in dominant follicles. In granulosa cells from preovulatory follicles, NPPC mRNA increased at 3 and 6 h after systemic GnRH treatment, but decreased at 12 and 24 h to similar levels observed in samples collected at 0 h. After GnRH treatment, NPR1 mRNA was upregulated at 24 h, NPR3 mRNA gradually decreased after 3 h, while NPR2 mRNA was not regulated. The mRNA expression of the enzyme FURIN increased at 24 h after GnRH treatment. These findings revealed that the expression of mRNA encoding important components of the NP system is regulated in bovine granulosa cells during follicular deviation and in response to GnRH treatment, which suggests a role of NP system in the modulation of these processes in monovulatory species.     

饲养管理、环境及体况对妊娠母猪繁殖性能影响的研究进展

在母猪饲养过程中,通过考虑到个体差异可以降低饲料成本,从而提高动物生产效率.因此,对母猪进行精准饲喂可以提供有关动物生产性能和生活条件的实时信息,这些信息应被集成到需求估计中.到目前为止,只有体重和背膘厚度的生产数据被集成到个体营养需求计算中.但文献报道,健康状况和行为(如身体活动、社会行为和在围栏中的位置)会强烈影响...     

梅山猪与杜洛克猪中等卵泡差异表达基因的鉴定

本试验采用抑制性消减杂交技术构建了卵泡期第4天梅山猪和杜洛克猪中等卵泡M2组织差异表达的消减cDNA文库,从中筛选差异表达的基因,并通过实时荧光定量PCR对其进行验证,利用DAVID软件对差异表达的基因进行聚类分析。结果表明,从梅山猪和杜洛克猪M2卵泡消减文库中筛选得到了148和75个差异表达的ESTs,分别含有125和60个已知的基因。实时荧光定量PCR验证结果与筛选结果相符。GO功能分类注释到调控代谢、细胞循环、生物合成、胞内转运、类固醇雌激素受体和刺激等生物学过程。KEGG Pathway分析表明有6个基因参与TGF-beta信号通路,5个基因参与卵母细胞减数分裂信号通路,7个基因参与类固醇雌激素受体信号通路,推测TGF-beta信号通路中的基因可能调控猪卵泡的发育。研究结果为深入探讨卵泡发育机理和对繁殖性状影响的遗传机理奠定了基础。     

梅山与长白母猪粪样微生物体外发酵八种纤维底物的特性比较

本研究旨在比较不同品种母猪(梅山猪与长白猪)粪样中微生物对不同纤维底物的体外降解能力,同时分析粪样中的主要纤维降解菌数量。采集梅山(n=5)和长白(n=5)母猪新鲜粪样作为发酵接种物,以果胶、纤维素、菊粉、麦壳、麸皮、木聚糖、玉米芯渣及苜蓿作为纤维底物进行体外发酵,测定产气量和发酵液挥发性脂肪酸(volatile fatty acid,VFA)浓度。粪样同时用于提取细菌总核酸,变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)和real-time PCR对菌群区系进行分析。体外发酵结果表明,从发酵后9 h至96 h结束,长白猪接种物各组的累积产气量、有机物校正产气量分别显著(P<0.05)和极显著(P<0.01)高于梅山猪,长白猪T_1/2和T_max显著低于梅山猪(P<0.05),且发酵终产物中乙酸和总VFA浓度显著高于梅山猪接种物(P<0.05),整个发酵过程中不同底物间累积产气量差异显著(P<0.05),累积产气量从高到低的组别依次为:菊粉>麸皮>果胶>苜蓿>麦壳>玉米芯渣>木聚糖>纤维素。DGGE分析表明,梅山与长白母猪粪样菌群图谱中存在许多共同条带。Real-time PCR定量分析表明,梅山母猪粪样中的总细菌的16S rRNA基因拷贝数显著高于长白母猪(P<0.05),而拟杆菌、产琥珀酸丝状杆菌、黄化瘤胃球菌和白化瘤胃球菌等纤维降解菌数量及其占总菌比例差异均不显著(P>0.05)。结果显示,尽管2个品种母猪粪样中纤维降解菌数量无显著差异,但是长白母猪粪样微生物体外发酵纤维底物的能力高于梅山母猪。     

Phenotypic and genetic variation in longevity of Polish Landrace sows

The influence of some production traits on the longevity of Polish Landrace sows was evaluated using survival analysis. Estimates of genetic parameters were obtained from the sire and animal components in linear and survival methodologies. Comparison between survival and linear models was based on heritabilities and ranking of estimated breeding values of sires. The same data set, 13 031 sows, was used for both methodologies, even in the presence of censored observations. The effects of herd*year and year*season of the first farrowing had the largest influence on the risk of culling of sows. Sows born in spring season (March–May) had a 24% (p < 0.001) lower hazard for removal than those born in winter (December–February). The age at first farrowing had a small but significant effect on culling: the hazard regression coefficient for this trait was 0.002 per day. Sows that had more piglets born alive and fewer stillborn in the first litter had a decreased risk of being culled. Within a contemporary group, slower growing gilts had decreased removal risk. The relative risk ratios show a marginal decreased rate of culling for sows with backfat thickness between 9.5 and 11 mm compared to the leaner sows. Loin depth had no effect on sow longevity. Heritability estimates ranged from 0.09 to 0.38 depending on the model and type of analysis. In survival analysis, all heritabilities for longevity were higher when analysed with sire models (0.21 and 0.38) compared to animal models (0.09 and 0.16). The use of animal or sire models in the linear analysis gave similar heritability estimates (0.12 and 0.10). Correlations between breeding values for sires were moderate and high, with absolute values from 0.51 to 0.99, depending on the model fitted and methodology. A stronger correlations within methodologies (0.83–0.99) than within models with different methodologies (0.51–0.63) were obtained.     

Separation and Purification of Ovulation-inducing Factors in the Seminal Plasma of the Bactrian Camel (Camelus bactrianus)

Ovulation in the Bactrian camel depends upon ovulation-inducing factors in the seminal plasma. The present study was conducted to isolate and purify the bioactive fractions from the seminal plasma of these camels. The seminal plasma was fractionated by anion-exchange chromatography, and six fractions were obtained. The bioactive potential of each fraction was estimated from its effect on rat pituitary tissue cultured in vitro and by the effect of an intramuscular injection of the fraction into female camels in vivo. Both the third fraction (F3) and the fifth fraction (F5) stimulated the release of LH in vitro and in vivo. In addition, female camels ovulated within 48 h after intramuscular injection of F3. However, neither F3 nor F5 had any significant effect on the secretion of FSH, either in vitro or in vivo. When F3 was further fractionated into four subfractions, the third subfraction (F3-3) still stimulated the in vitro release of LH, but not of FSH. An attempt to further purify the ovulation-inducing factors in F3-3 failed owing to the similarity of the molecular characters.     

Factors influencing estrus and ovulation in weaned sows as determined by transrectal ultrasound.

Characterization of factors influencing estrus and ovulation in sows may facilitate development of procedures for improving reproductive performance. The experiment was conducted in confinement during 1997 to 1999 using 174 Large White x Landrace sows. After weaning, sows were checked for estrus twice daily. In the 1st yr, transrectal ultrasound was performed once daily and in the 2nd yr twice daily at estrus and on every day until ovulation. The effects of lactation length (< or = 16 d, 17 to 24 d, 25 to 31 d or > or = 32 d), parity (1, 2, or > or = 3), season (winter, spring, summer, or fall) and weaning-to-estrus interval (3, 4, 5, or 6 to 8 d) and their interactions on estrual and ovulatory responses were studied. There was no effect of frequency of ultrasound on any response variable, so data across years were pooled. Percentage of sows expressing estrus within 8 d of weaning was influenced by lactation length (P < 0.001), with sows lactating < or = 16 d (35.2%) less likely to express estrus than sows lactating > or = 17 d (94%). A parity x season interaction was observed (P < 0.001) for estrus, with the lowest expression in parity 1 (73.0%) and parity 2 sows in fall (67.2%), compared with > or = parity 3 sows (98.1%). No explanatory variable had a significant effect on weaning-to-estrus interval (4.4 d) or on follicle size at estrus (8.1 mm). Ovulation hour after onset of estrus was affected by weaning-to-estrus interval (P < 0.01), with sows returning in 3 d ovulating at 46.2 h and between 6 and 8 d at 30.2 h. For sows that expressed estrus within 8 d of weaning, the percentage of sows ovulating was influenced by lactation length (P < 0.001) and weaning-to-estrus interval (P < 0.001). Sows that lactated < or = 16 d were less likely to ovulate (78.0%) than those lactating > or = 17 d (> 92%). Sows that returned to estrus in 3 d were also less likely to ovulate (79.5%) than sows returning > or = 4 d after weaning (> 92%). A parity x season interaction was also observed on ovulation (P < 0.001), with parity 1 and 2 sows less likely to ovulate after expressing estrus in fall and spring compared with parity 3 and greater sows. The data suggest lactation length, early return to estrus, and parity by season effects are associated with risk of failure to express estrus and ovulate.     

猪微注射基因导入系统影响受体受孕率及产仔率的几个因素

在应用显微注射、胚胎移植系统技术，进行猪ＯＭＴ／ＰＧＨ基因导入的研究中，对移入受体的胚数，ＰＭＳＧ处理受体以及不同的移植方法（自体移植与异体移植）等影响受体受孕率及产仔率的因素，进行了试验分析，结果表明：（１）移入受体的注射胚数分别为１０—１９枚、２０—２９枚、３０枚以上时，其受孕率为４５．５％、６４．７％和７１．４％，产仔率为８．０％、１９．６％和１４．５％，以移入２０—２９枚效率最高；（２）用ＰＭＳＧ对受体母猪做同期发情处理，其受孕率和产仔率比选择自然发情的受体分别下降２５％和８．５％；（３）采用自体移植的方式，在移入胚数基本相同的情况下（１５枚左右），比异体移植的受孕率和产仔率分别提高１４．３％和６．４％。     

Puncture and drainage of the subordinate follicles at timed artificial insemination prevents the risk of twin pregnancy in dairy cows

The objective of this study was to determine whether fluid drainage from the subordinate follicles by ovum pickup procedures prevents the risk of twin pregnancy without reducing the fertility of the cow. Lactating dairy cows with at least two follicles over 12 mm diameter located one on each ovary and selected from synchronized groups for fixed‐time insemination were assigned to a Control (n = 49) or Drainage (n = 49) group. The largest follicle was considered as the dominant follicle. Draining of all subordinate follicles (≥10 mm) was performed in the Drainage group. All drained follicles developed as a corpus luteum 7 days later. In the Control cows, the presence of two corpora lutea (55.1%) was lower (p = .003) than those in the Drainage cows (87.8%), whereas the incidence of twin pregnancies was 50% and 0% for the Control and Drainage groups, respectively (p < .001). Draining did not affect the pregnancy rate. These results indicate that puncture and drainage of the subordinate follicles at insemination may eliminate the risk of twin pregnancies and reduce the risk of subsequent pregnancy loss by increasing the incidence of additional corpora lutea.     

Resynchronization of ovulation with new and reused intravaginal progesterone‐releasing devices without previous pregnancy diagnosis in Bos taurus indicus cows subjected to timed‐artificial insemination

The study aimed to evaluate pregnancy per artificial insemination (P/AI) of cows subjected to synchronization and resynchronization in ovulation protocols using intravaginal progesterone‐releasing insert (P4) before pregnancy diagnosis (PD) and the relationship of PR with the diameter of preovulatory follicles (ØPOF) before TAI. Cows (n = 378) were distributed into two groups: a resynchronization group with new devices (GRN; n = 185) and resynchronization group with used devices (GRU; n = 193). On Day 0, both groups received a new P4 and estradiol benzoate (EB). On D8, P4 removal + D‐cloprostenol + eCG + estradiol cypionate (EC) was done. On d10, TAI was conducted. On d32, cows were resynchronized and divided into two groups, GRN (n = 185) and GRU (n = 193). The GRN group received a new P4 + EB, and the GRU group received a used P4 + EB. On d40, the P4 was removed + PD. The non‐pregnant cows received D‐cloprostenol + eCG + EC. US was done again on d42 to determine ØPOF before the second TAI. The P/AI of the GRN and GRU groups after synchronization were 56.2% and 57.0% (p = 0.87), respectively, and those after resynchronization were 58.0% and 37.3% (p < 0.008), respectively. The P/AI of the GRN and GRU groups observed after TAI (synchronization + resynchronization) were 81.6% and 73.1%, respectively (p = 0.047). No difference (p = 0.067) in ØPOF between the pregnant and non‐pregnant cows in the GRN was found, whereas the GRU group showed a significant difference (p = 0.003). Resynchronization protocols optimized the P/AI in both groups. New intravaginal devices resulted in greater P/AI and P/AI accumulation in resynchronization as compared with the GRU; the ØPOF was related with P/AI.     

Studies on immunoglobulins and trypsin inhibitor in colostrum and milk from sows and in serum of their piglets.

The concentrations of IgG, IgM, IgA and the specific sow colostrum trypsin inhibitor (SCTI) were measured by radial immunodiffusion in colostrum and milk samples from sows and in serum samples from their offspring during the suckling period. A clear time dependence was found for all the measured variates in both whey and serum. Statistically significant positive correlations were found between, on the one hand, concentrations of IgG and IgA, but not IgM, in sera from 39 suckling piglets 1 and 3 days old, and, on the other hand, concentrations of the same immunoglobulins and of the trypsin inhibitor in maternal colostrum (n = 7). Multiple regression analyses showed that at day 1 and day 3 the levels of both IgG and IgA in serum samples from the suckling piglets were positively influenced by both the SCTI and the IgG or IgA contents in maternal colostrum.     

A comparison of seasonal effects on fertility of Landrace and Large White sows in a subhumid tropical environment

Forty sows comprising equal numbers of Landrace (LR) and Large White (LW) breeds were studied for 20 months to determine the effects of dry and rainy seasons on their fertility traits in Nigeria. Ambient temperature (14.0-35.5 degrees C) was lowest at night and highest in the day and peaked during the dry season. A relative humidity range of 60-82% peaked during the late rainy season. LR produced 218 and 278 piglets from 23 and 28 litters, while LW produced 193 and 316 piglets from 20 and 30 litters during dry and rainy seasons respectively. Fertility traits did not differ significantly between the breeds due to season (P greater than 0.05). Mean post-weaning oestrus at 10.9 and 9.0 days and preweaning mortality rates of 14.2% and 16.9% during dry and rainy seasons for LR differed significantly (P less than 0.5) from those of LW which were 12.2 and 8.2 days and 14.5% and 18.9% respectively. The significance of seasonal effects on sow fertility and necessary management techniques are discussed.     

氧化应激与母仔猪肠道菌群的互作及其营养调控

繁殖周期内母猪肠道菌群稳态的正常维持对其繁殖效率、仔代的健康状况和生长速度至关重要。在生产中,多层次因素导致母猪机体活性氧增加,繁殖周期内产生进程性氧化应激,进而破坏母体肠道菌群生态平衡,影响母仔猪的正常生理活动,降低养猪业生产效率。目前通过营养调控缓解母仔猪氧化应激,维持肠道菌群的稳态受到了广泛的关注。本文结合国内外研究进展,对氧化应激与繁殖周期内母猪和仔猪肠道菌群的互作及其营养调控进行综述,旨在为提高母猪年生产力提供理论依据和技术支撑。     

ORIGINAL ARTICLE: Effects of dietary glucose inclusion on reproductive performance,milk compositions and blood profiles in lactating sows

Twenty‐four multiparous sows were used to investigate the effects of dietary glucose inclusion on reproductive performance, milk compositions, blood metabolites and hormones during lactation. The sows were randomly assigned to four treatments and each treatment had six replicates (sows). The diets were added with 0%, 1%, 3% or 5% glucose at the expense of corn and fed to sows for 24 days. The loss of backfat thickness during lactation was quadratically decreased (p = 0.008) and the wean‐to‐oestrus interval was shortened (linear, p = 0.013; quadratic, p = 0.009) with increasing levels of dietary glucose supplementation. The reproductive performance was not affected (p > 0.05) by different dietary glucose contents. Increased concentrations of total solid and fat in milk were noted (p < 0.05), whereas there was no difference on colostrum compositions. With increasing levels of dietary glucose inclusion, the concentrations of blood urea nitrogen (p = 0.004) and glucose (p = 0.029) were linearly increased at weaning. The concentrations of insulin were increased at post‐farrowing (linear, p = 0.027; quadratic p = 0.013) and weaning (linear, p = 0.029; quadratic, p = 0.017), respectively. Furthermore, the pulses of insulin and FSH at weaning were linearly (p = 0.049) and quadratically (p = 0.015) increased with the increasing levels of dietary glucose inclusion. In conclusion, this study indicated that inclusion of 3% glucose in lactating diet could reduce backfat loss, increase milk fat and have no negative effect on reproductive performance in multiparous sows.     

The Effect of Cloprostenol on the Incidence of Multiple Ovulation and Anovulatory Hemorrhagic Follicles in Two Mares: A Case Report

Reproductive records of the entire lives of two mares with abnormally high incidence of multiple ovulation and hemorrhagic anovulatory follicles were analyzed retrospectively. Chi-square analysis was used to test statistically the effect of cloprostenol, a prostaglandin F2 analog, on the incidence of multiple ovulations, hemorrhagic anovulatory follicles, and its ultrasonographic appearance. A total of 319 estrous cycles during a 17-year period were analyzed. Cycles induced with cloprostenol were more likely (P < .000) to develop hemorrhagic anovulatory follicles than spontaneous cycles. The incidence of multiple ovulation was higher in induced cycles than in spontaneous cycles in one of the two mares.     

Detection of Torque teno sus virus 1 and 2 in tissues from stillborn piglets delivered by sows via natural farrowing

We detected Torque teno sus virus 1 and 2 (TTSuV1 and TTSuV2) in tissue samples from 18 stillborn piglets using nested polymerase chain reaction. The detection rates of TTSuV1 and TTSuV2 were 78% and 50%, respectively, with 83% of the stillborn piglets positive for TTSuV1 or TTSuV2. TTSuV1 was detected highest in the liver (72%) followed by heart (56%), spleen (38%) and tonsils (38%) while TTSuV2 was detected highest in the tonsils (38%) followed by liver (33%), spleen (25%), and heart (17%). These results indicate that TTSuVs are commonly present but not equally distributed among the tissues of stillborn piglets.     

妊娠母猪饲粮中不同苜蓿鲜草替代量对其生产性能的影响

在母猪妊娠期用不同比例的紫花苜蓿鲜草代替部分精料,研究其对生产性能及经济效益的影响。试验选用胎次、配种时间、上胎产仔数、体况等基本一致的大长二元母猪30头,采用单因子完全随机设计,共分为6个组,每组5头猪,每头猪1个重复。对照组饲喂基础日粮,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组分别用紫花苜蓿鲜草代替10%,20%,30%,40%的基础日粮(按干物质折算),试验Ⅴ组用紫花苜蓿草粉代替20%的基础日粮。结果表明:1)和对照组相比,在妊娠母猪饲粮中无论是用不同比例的紫花苜蓿鲜草还是用20%的苜蓿草粉代替精料,均提高了饲粮中粗蛋白质、粗灰分、中性洗涤纤维、酸性洗涤纤维、钙和总磷的表观消化率,其中试验Ⅲ组的提高幅度最大,极显著高于对照组(P＜0.01);随着紫花苜蓿鲜草替代量的增加,粗脂肪的表观消化率依次下降,但苜蓿草粉组和对照组几乎无差别。2)随着紫花苜蓿鲜草替代量的增加,繁殖期母猪体增重和背膘增加量均呈先升后降的趋势,而妊娠期母猪背膘增加量和泌乳期母猪背膘减少量依次下降。和对照组相比,在妊娠期母猪饲粮中以紫花苜蓿鲜草和草粉替代等干物质量的精料,均提高了母猪的采食量,其中试验Ⅲ组的采食量最大,极显著(P＜0.01)高于对照组。紫花苜蓿鲜草和草粉替代精料后,断奶至发情时间间隔有所缩短,但各组之间差异不显著(P＞0.05)。3)随着紫花苜蓿鲜草替代精料量的增加,提高了初生窝产仔猪总数、初生窝产活仔数、断奶仔猪数、断奶窝重和断奶窝平均日增重;鲜草试验组(试验Ⅲ组除外)的断奶仔猪个体重和对照组相似,试验Ⅴ组显著(P＜0.05)高于对照组和其余各试验组,试验Ⅴ组的断奶仔猪日增重也极显著(P＜0.01)高于对照组和其他试验组。综合分析认为,母猪妊娠期饲粮中用30%的紫花苜蓿鲜草代替精料其生产性能和经济效益最佳。