Impact of postovulatory food deprivation on the ova transport, hormonal profiles and metabolic changes in sows.

The effect of food deprivation on ova transport, hormonal profiles and metabolic changes was studied in 20 crossbred multiparous sows during their second oestrus after weaning. To determine the time of ovulation, transrectal ultrasonographic examination was performed. The sows were divided into 2 groups, one control group (C-group), which was fed according to Swedish standards, and one experimental group (E-group). The E-group sows were deprived of food from the first morning meal after ovulation until slaughter. Blood samples were collected every second hour from about 12 h before expected ovulation in the second oestrus after weaning until slaughter and were analysed for progesterone, prostaglandin F2 alpha-metabolite, insulin, glucose, free fatty acids and triglycerides. All sows were slaughtered approximately 48 h after ovulation and the genital tract was recovered. The isthmic part of the oviduct was divided into 3 equally long segments and flushed separately with phosphate buffered saline (PBS). Uterine horns were also flushed with PBS. A significantly greater number of ova were found in the first and second part of the isthmus in the E-group (p = 0.05) while in the C-group most of the ova were found in the third part of the isthmus or the uterus (p = 0.01). The level of prostaglandin F2 alpha-metabolite was significantly higher in the E-group compared with the C-group. The concentration of progesterone increased in both groups after ovulation but there were no significant differences between the groups. The other blood parameters showed that the food-deprived sows were in a catabolic state. The 48 h period of fasting results, directly or indirectly in an delayed ova transport, which may be due to a delayed relaxation in the smooth circular muscle layer of the isthmus.     

Suppression of ovarian progesterone production in dairy cows using an implant of GnRH-agonist (deslorelin) for the purpose of evaluating progesterone metabolism

OBJECTIVE: To evaluate the potential of an implant of a GnRH-agonist (deslorelin) to create a progesterone free animal suitable for studying progesterone (P4) metabolism in intact cows by measuring blood P4 and faecal P4 metabolites. METHODS: Experiment 1: Eighteen non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to one of three groups to study plasma P4 concentrations preceding an intravaginal insert. These groups comprised: i) a deslorelin group (GnRH-agonist implanted); ii) a PGF group receiving two injections of prostaglandin (PGF2alpha) 12 days apart; and, iii) an ovariectomised (OVX) group. An intravaginal device (CIDR) was inserted into the vagina of each animal and left in place for 11 days. Plasma P4 concentrations were measured during the study period. Experiment 2: Twelve non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to two groups: i) a deslorelin group (GnRH-agonist implanted); and ii) an ovariectomised group. Plasma P4 and faecal P4 metabolites (20-oxo-pregnanes, 20alpha-OH and 20beta-OH) were monitored for a period of 5 weeks. RESULTS: Experiment 1: Average plasma P4 concentration did not differ between the three groups (1.28, 1.43 and 1.55 ng/mL for deslorelin, OVX and PGF cows, respectively, P = 0.8) during the period of supplementation. Experiment 2: There was no difference in plasma P4 (mean plasma P4 < 0.02 ng/mL, P = 0.9) and faecal P4 metabolites between deslorelin and OVX cows 2 weeks after the implantation (P = 0.7). CONCLUSIONS: These data showed that a GnRH-agonist (deslorelin) implant may be used as an alternative to ovariectomy to create a progesterone free animal suitable for studying the metabolism of administered P4.     

The post-ovulatory rise in progesterone is lower and the persistence of oestrous behaviour longer during the first compared with the second cycle of the breeding season in mares

Mares are seasonally polyoestrous breeders. Therefore, the first ovulation of the season, following winter anoestrus, is the only cycle in which mares ovulate without the presence of an old CL from the previous cycle. The objective of this study was to compare the length of oestrous behaviour, and plasma progesterone concentrations during the early post-ovulatory period between mares after the first and second ovulation of the breeding season. Overall, 38 mares and 167 oestrous periods were used in the study. From those, 11 mares were used during the first and subsequent oestrous period to measure and compare the post-ovulatory rise in progesterone concentration, whereas all the mares were used to compare the length of the post-ovulatory oestrous behaviour between the first and subsequent cycles of the breeding season. The persistence of the post-ovulatory oestrus was longer (p < .001) following the first ovulation of the year (median of 52 h) compared with the subsequent ovulations (median of 36 h for second and later ovulations groups; n = 38 mares). The progesterone concentration at any of the four 8 h-intervals analysed (28, 36, 76 and 84 h post-ovulation) was lower (p < .01) following the first versus the second ovulation of the year. By 36 h post-ovulation the progesterone concentration of mares at the second ovulation of the year had passed the threshold of 2 ng/ml (2.1 ± 0.33 ng/ml), whereas in the first cycle it was 1.2 ± 0.13 ng/ml. In conclusion, mares had lower progesterone concentrations in their peripheral circulation and longer persistence of oestrous behaviour following the first ovulation of the year compared with the second and subsequent ovulatory periods of the breeding season.     

用孕酮阴道栓治疗乏情牛的试验

用孕酮阴道栓治疗乏情牛,一至三天内同期发情率为89.6%。72头牛采用冷冻精液授精,第一情期受孕率为33.3%,笫二情期受孕率为19.4%。证明孕酮阴道栓治疗乏情牛是有效的。     

全放牧婆罗门牛和BMY牛的超数排卵效果及激素水平比较

为了比较婆罗门牛和BMY牛的雌二醇(E2)、孕酮(P4)水平及胚胎生产潜力,并探讨MOET技术在BMY牛扩繁中的应用前景,采用进口激素(日本产FSH 24~36 mg+美国产PG 35 mg)和国产激素(国产FSH 10~12 mg+国产PG 0.8 mg)对全放牧婆罗门牛和BMY牛进行超排,并于超排前(同期发情第7天)、超排开始、超排第3天、超排发情当天和胚胎回收当天采集血液,采用RIA法分析血浆中的E2和P4水平。结果表明,BMY牛的黄体数和获胚(卵)数、可用胚数分别较婆罗门牛高2.09个和0.95、0.36枚,但差异不显著(P>0.05);BMY牛的排卵率较婆罗门牛高18.46%(P<0.01),而可用胚率则较婆罗门牛低2.55%(P<0.01)。BMY牛在5个处理时段的E2和P4平均值分别较婆罗门牛高0.58 pg/mL(P<0.01)和1.44 ng/mL(P>0.05),在各处理时段的P4水平变化规律几乎与婆罗门牛一致,E2/P4值为婆罗门牛的5.16倍。结果提示,BMY母牛的E2和P4水平高于婆罗门牛,在激素水平和繁殖性能方面表现出一定的杂种优势;E2水平低是婆罗门牛发情微弱和排卵率低的主要原因之一;在同等放牧管理和超排处理条件下,婆罗门牛及其杂种BMY牛对外源激素的敏感性基本一致,具有同等的胚胎生产潜力。     

猪孕酮酶免疫分析及释放激素对猪孕酮含量的影响

应用孕酮单克隆抗体（ＰＭｃＡｂ）和孕酮－辣根过氧化物酶（Ｐ－ＨＲＰ）通过微量板对猪血清孕酮进行酶免疫分析。结果表明：１：２．５×１０￣４浓度的ＰＭｃＡｂ和１：５×１０￣４浓度的Ｐ－ＨＲＰ之间具有较强的亲和力，母猪在发情配种前注射释放激素类似物（ＬＲＨ－Ａ＿３）能提高怀孕早期的孕酮含量，怀孕母猪在怀孕１５天时的孕酮含量是未孕猪的近２倍，分别为１７．２４ｎｇ／ｍＬ和９．５０８ｎｇ／ｍＬ。     

日粮中高碘对母鸡繁殖性能的影响

在２５周龄母鸡日粮中添加高剂量碘化钾，持续１６周，观察产蛋率，种蛋受精率及孵化率的变化，并用ＲＩＡ法测定鸡血浆中的雌激素、孕酮浓度．结果表明，高碘组母鸡产蛋率下降，种蛋爱精率无明显变化但孵化率降低．母鸡血浆雌激素的基础分泌量无显著变化，但高碘引起孕酮基础分泌量升高，而且导致雌激素、孕酮的周期分泌率紊乱．     

雌二醇和孕酮对小鼠子宫半胱亚磺酸脱羧酶基因表达和牛磺酸含量的调控

实验主要研究了17β-雌二醇(E2)和孕酮(P4)对小鼠子宫组织中半胱亚磺酸脱羧酶基因(CSD)表达和牛磺酸含量的调控。给去卵巢小鼠分别皮下注射植物油(对照组)、17β-雌二醇(E2)、孕酮(P4)、E2和P4、E2和氟维司群(ICI 182780)、P4和米非司酮(RU486),24h后观察各组小鼠子宫中CSD的表达和牛磺酸的含量。Real-time PCR和Western blot定量分析结果显示,每只小鼠注射1μg E2能够显著抑制CSD的mRNA和蛋白的表达,6mg P4能够显著促进CSD mRNA和蛋白的表达,其受体抑制剂RU486和ICI182780都能逆转它们的作用。高效液相色谱(HPLC)测定结果显示,注射1μg E2和6mg P4分别下调和上调子宫组织中牛磺酸的含量。上述结果提示E2和P4可能通过受体途径参与调节子宫CSD的表达,从而调节子宫中牛磺酸含量。     

泌乳期中国荷斯坦牛转化孕酮浓度的影响因素分析及其表型预测

【目的】本研究基于试验测定的中国荷斯坦牛血液和乳汁中的孕酮浓度表型，探究了影响中国荷斯坦牛体内孕酮分泌的环境因素、孕酮浓度的变化趋势、孕酮浓度与乳成分的关联程度以及血乳中孕酮浓度的预测方法。【方法】试验于2021年8月在北京、山东两个牧场采集不同胎次、泌乳阶段和妊娠状态的中国荷斯坦泌乳牛的奶样、尾根血样，测定孕酮浓度，最终获得402条乳汁孕酮浓度和298条血液孕酮浓度表型用于数据分析。对孕酮浓度进行数据转化使其近似服从正态分布后，采用固定效应模型探究胎次、泌乳阶段、妊娠状态、牧场等固定效应对奶牛孕酮表型的影响，运用R语言cor函数计算孕酮与各乳成分间的关联，并利用偏最小二乘法和个体及乳成分信息对孕酮浓度进行预测，以建立孕酮浓度表型高通量获取手段。【结果】妊娠状态对转化乳汁孕酮浓度存在极显著影响（P<0.01），胎次、场效应对转化乳汁孕酮浓度均有显著影响（P<0.05），而转化血液孕酮浓度只受到妊娠状态影响（P<0.01）；全乳固体、乳脂率、乳蛋白率、脂蛋比与转化乳血孕酮浓度均存在显著或极显著的正相关关系（r=0.14~0.37，P<0.05；P<0.01）；基于本试验数据，乳成分与个体信息对转化乳血孕酮浓度的预测准确性不高（R²=0.030~0.17），但如果增加血液或乳汁的转化孕酮浓度对乳汁或血液的转化孕酮浓度进行预测，预测效果则有大幅提升（R²=0.40）。【结论】影响泌乳期中国荷斯坦牛转化孕酮浓度的因素除妊娠状态外，可能还包括饲养条件与胎次。此外转化孕酮浓度与乳脂率、乳蛋白率等乳成分呈极显著相关。基于乳成分信息与转化孕酮的关系，获得了对中国荷斯坦牛乳血转化孕酮浓度预测的可用策略，为今后牧场的繁殖辅助管理、奶牛育种新性状研发以及孕酮浓度的高通量获取等提供了新思路。