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1.
This study aimed to characterize the annual reproductive cycle of Santa Inês sheep in the Fluminense lowland region (latitude 22° 27′ 45″ south, Rio de Janeiro, Brazil) between September 2011 and August 2012. Ten ewes were maintained in a semi-intensive system under natural photoperiods with access to pasture and shelter. Blood samples were collected every 2 weeks to determine plasma progesterone concentrations. The body condition score (BCS) was determined each month. There was no seasonal variation in the plasma progesterone concentration from the months of September to January, April, and May to August. In the months of February and April, the plasma hormone levels were higher than August to November. Seventy percent (7/10) of the sheep studied had short seasonal anestrus. The periods of anestrus were concentrated between the months of September and December (spring season) in 85.7 % (6/7) of the cases evaluated. In these cases, 57.1 % (4/7) also had short periods of reproductive inactivity during other months of the year. The progesterone values obtained in the spring corroborate the higher reproductive anestrus observed in this season. Higher plasma progesterone values were found in summer and autumn with reduction in the winter to lower values in the spring. No changes in the BCS during the study period were observed. Under the studied conditions, the Santa Inês sheep showed a low degree of reproductive seasonality. However, some individual ewes had seasonal anestrus during the spring. Further studies that include management techniques are needed to improve reproductive efficiency without hormone therapy in this breed under tropical conditions.  相似文献   

2.
The reproductive activity of the redbilled oxpecker Buphagus erythrorhynchus is governed primarily by the effects of rainfall and the onset of the laying cycle is dependent on the time of year at which the rain occurs. At the onset of the rainy season in August or early September the biomass of the Ixodldae increases on the mammalian symbionts and is made use of for feather synthesis during moult. During October with a significant increase in the biomass of Tabanidae it is possible to accumulate a large enough protein reserve to initiate breeding.  相似文献   

3.
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.  相似文献   

4.
Seasonal endocrine changes in 5 non-bred and 10 pregnant Alaskan reindeer have been documented. Blood samples were collected from early September until early May, spanning the breeding season, gestation, or the anovulatory period. Plasma was analyzed by RIA for progesterone (P4), estradiol-17beta, estrone, and estrone sulfate. Elevated P4 in 80% of the reindeer at the onset of the study indicated that ovarian activity had been initiated. The median date for the onset of the first recorded full-length ovulatory cycle was September 23. In nonbred reindeer, the mean ovulatory cycle length from September to May was 24 +/- 1 d (range 18 to 29 d). Nonbred females continued to cycle throughout the winter, displaying 6 to 8 ovulatory cycles after the beginning of blood sampling. Cycle length (mean 22 to 24 d) did not vary between individuals (P = 0.170) or over the course of the winter (P = 0.244). In early April, ovulatory cycles ceased with normal demise of the corpus luteum in 2 females, whereas the remaining 3 females formed apparently persistent corpora lutea. Natural service breeding occurred between September 10 and October 2, and P4 profiles indicated that all breeding females conceived to the first mating. Concentrations of P4 rose steadily after conception and remained elevated throughout gestation, with mean concentrations not varying significantly (P = 0.104) from 4 to 28 wk of gestation. Estrogens all followed patterns similar to each other, remaining at baseline concentrations until approximately 24 wk of gestation and rising coincidently as P4 declined just before parturition. There was a continual overlap throughout the winter in peak P4 concentrations observed in cycling and pregnant reindeer. Calving occurred between April 8 and May 2, resulting in a mean gestation length of 211 +/- 2.2 d (range 198 to 221 d). Information from this study can be used by Alaskan reindeer producers to improve management and profitability of reindeer production.  相似文献   

5.
S.C. Broni 《African Zoology》2013,48(4):241-245
The inshore distribution and foraging behaviour of jackass penguins Spheniscus demersus were studied between December 1982 and August 1983 in waters close to breeding islands in Saldanha Bay, South Africa. The use of a sail-boat permitted close observation of foraging penguins with minimal apparent disturbance. Penguin numbers at sea were lowest in December, when most birds were confined to islands during moult, and highest during the winter breeding season. Although most penguin group sizes were small (one or two birds), over 44% of penguins occurred in groups of more than 10 birds. Three typical penguin group formations occurred at sea: ‘facing-search’, ‘line-abreast’, and ‘pointed-ovoid’. Penguins also foraged in association with other seabirds and marine mammals. The importance of large foraging groups suggests that the jackass penguin relies on shoals of similar sizes to those taken by the commercial purse-seine fishery, increasing the potential for "o competition.  相似文献   

6.
Fecal progesterone content was measured by time-resolved fluoroimmunoassay (TR-FIA) in the sika doe (Cervus nippon). The total recovery rate of fecal progesterone by twice extraction with diethylether was about 60%. The displacement curve of TR-FIA with serial doses of fecal extract (0.156-5.0 mg feces) was closely parallel to that of the reference standard. Fecal progesterone content was correlated with that of plasma (r=0.829, n=16), but the values were 100-fold higher in feces than in plasma. Fecal progesterone content periodically changed during the breeding season suggesting the estrous cycle in the doe. The fecal progesterone content was higher between the estruses, and decreased after estrus. The time between the onset of estrous signs and the lowest fecal progesterone content was 1-2 days suggesting the time required for hepatic metabolism and intestinal passage. Fecal progesterone content was also decreased around the time of vaginal discharge. The discharge took place within a few days, suggesting a short luteal phase. Not of all decreases in fecal progesterone values were preceded by estrous behavior or vaginal discharge. Fecal progesterone content was further increased in pregnancy rather than in the preceding estrous cycle and the levels were maintained up to term. These results suggest that fecal progesterone measurement is a useful tool for non-invasive analysis of luteal function in the sika doe. The TR-FIA kit, designed for the human hospital market, was shown to be successfully utilized for fecal assay in the sika doe with minor modifications.  相似文献   

7.
This study aims to characterize the reproductive patterns in Asinina de Miranda jennies during the non‐breeding season. Reproductive activity was surveyed in 12 females, aged between 3 and 18 years old, using ultrasound and teasing with a jack. The animals were monitored from September to April, six in each consecutive year. Of these 12 females, nine showed disruption to the normal pattern of ovarian activity during the non‐breeding season. Loss of normal cyclicity included anoestrus (41.7%), silent ovulatory oestrus (25%), and persistence of corpus luteum (8.3%). Only three females maintained a regular cyclic pattern with oestrous behaviour during the non‐breeding season. Anoestrus began in early November and lasted for an average of 147 ± 28 days (113–191 days), ending near to the spring equinox. Onset of silent oestrous cycles began more erratically, between October and February. In both groups the first behavioural ovulation of the year occurred around the time of the spring equinox. Disrupted reproductive activity was preceded by a shorter oestrous cycle only in females entering anoestrus. The mean follicle size in the first ovulation of the year was larger than in the reproductive season (44.7 ± 2.45 mm vs 39.2 ± 3.60 mm) in anoestrous jennies with protracted oestrus. Though age and body condition score (BCS) were associated, changes in BCS below a threshold of four points (for anoestrus) and five points (for silent oestrus) contributed greatly to disruption of reproductive cycles. BCS in females with regular oestrous cycles during the winter season remained unchanged or exceeded five points prior to the winter solstice.  相似文献   

8.
Inhalt Bei 4 trächtigen und 4 nicht trächtigen Schafen wärden während der zyklischen und anöstrischen Phasen vom 14.11.83—24.8.84 die beta-Endorphinkonzentrationen im Plasma bestimmt. Die beta-Endorphinwerte der beiden Tiergrupppen wurden in 12 Zeitperioden mit je 40 Proben eingeteilt. Das beta-Endorphin (beta-End) zeigt saisonale Schwankungen mit höheren Werten im Spätherbst (Nov—Jan.), minimale Werte während der Anöstrie (Feb.—Juli) und maximale Konzentrationen im Frühherbst (Juli—Aug.). Zwischen graviden und nicht trächtigen Tieren bestehen keine signifikanten Unterschiede in den ersten 3 Zeitperioden (Nov.— Jan.), danach unterscheiden sich die Gruppen in den übrigen Perioden (P <.01), mit Ausnahme der 6. (Feb.— März) und 10. Zeitperiode (Juni—Juli). Die beta-End-Werte der Mutterschafe liegen während der Gravidität und Laktation tiefer (P ≤.01). Während der Laktation sind Prolaktin und Cortisol erhöht, wobei das Cortisol möglicherweise die beta-End-Sekretion direkt oder indirekt hemmt. Es bestehen signifikante Korrelationen zwischen beta-End: LH, beta-End: Cortisol und LH: Cortisol, die mit der Trächtigkeit, Laktation und derPhotoperiodik im Zusammen-hang stehen. 2 weitere Schafe wurden im November 1983 kastriert. Bei diesen Tizren wurden ebenfalls 12 Zeitperioden zu je 10 Proben gewählt. Beide Schafe zeigen photoperiodische beta-End-Schwankungen ähnlich wie bei intakten Tieren. In den ersten beiden Perioden im November und Dezember liegt das beta-End beim Schaf 28 sehr hoch und fällt danach kontinuierlich ab bis zum Ende der anöstrischen Phase im Juni. In der zyklischen Phase im Juli und August liegt der beta-End-Spiegel höher. Nach der Kastration steigt das LH bis zum Beginn der Anöstrie (Feb.–März) und liegt etwas tiefer in der 7. und 8. Periode im März–Mai. Danach erfolgt eine geringe Zunahme des LH-Gehalts bei Versuchsende im August. Beim Schaf 864 sind die Progesteronwerte während 42 Tagen nach Kastration ≤ 0.2 ng/ml. Danach beg'nnt das Progesteron anzusteigen und zeigt saisonale Schwankungen sowie einen photoperiodi-schen LH-Verlauf Zwischen beta-End und Progesteron besteht eine inverse Beziehung (3-.19, P ≤.05), was darauf hinweist, daß das Progesteron von der Nebenniere stammen könnte. Contents: Beta-endorphin during reproductive and anestrous season in the ewes The beta-end-concentration of each 4 pregnant and non pregnant ewes were measured during the breeding and anestrous sesons from 14.11.83—24.8.84 organized into 12 time groups of 40 values each. Hormone concentrations were increased during the breeding season (Nov.–Dec.), dropped to low levels in anoestrus (Feb.–July) and were high again during the reproductive period in July and August. In the first three time groups (Nov.–Jan.) there were no differences in beta-end-concentration between pregnant and non pregnant ewes. Thereafter the pregnant group had lower hormone levels during the remainder peirods (P <.01), except of time groups 6 (Feb.–March) and 10 (June–Luly). During lactation the level of prolactin and crotisol are increased. High coritsol concentration could depress beta-end-secretion. There are significant correlations between beta-end: LH, beta-end: cortisol which are related to pregnancy, lactation and photoperiods. Two sheep had been ovariectomized in November 1983. For the beta-end-concentrations we had choosen 12 time groups of 10 values each. Both animals experienced photoperiodic fluctuations in beta-end-levels during the breeding and non breeding seasons. Sheep 28 had high beta-end values in November and December. Thereafter the hormone concentration dropped and reached a minimum at the end of anoestrus (June—July). The beta-end increased again in July and August. The beta-end increased again in July and August. The LH started increasingin December and reached a maximum at the start of anoestrus (June—July). After a small drop of the LH concentration, LH increased again until August. In ewe 864, after a period of low progesterone levels (< 0.2 ng/ml) during the first 42 days post castration, progesterone increased during the breeding season and exhibited thereafter seasonal patterns for progesterone and LH concentrations. At the end of blood sampling in August HL increased to high levels during the reproductive season while progesterone was again elevated. Between beta-end and progesterone exists a negative correlation (r-.19, P ≤ 0.05) which may indicate that progesterone in these ovariectomized animals might be of adrenal origin.  相似文献   

9.
The aim of this study was to determine the level and duration of progesterone secretion during the sequential oestrous cycles in fat-tailed Tuj ewes following tactile and visual separation of rams during the breeding season. For these purposes, rams were separated from the main flock for 50 days starting from the beginning of the breeding season and 21 ewes were randomly selected for the current experiment. In order to assess luteal activity and the length of oestrous cycles, the ewes were blood-sampled thrice or twice weekly for the measurement of progesterone in plasma. The data showed that 3 +/- 0.2 oestrous cycles were observed in this time window, and the first oestrous cycle observed was shorter (P < 0.05) than the following cycles (mean +/- SEM, 14.6 +/- 0.82, 16.5 +/- 0.48 and 17.0 +/- 0.54 days, respectively, for cycles 1, 2 and 3). Progesterone production was significantly lower in the first oestrous cycle compared with the second and third cycles on days 9, 12 and 14 of the cycles. The follicular periods of ewes showed four accumulations (maximum values using a 3-day moving average technique) throughout the study and the percentages of ewes at each accumulation (peak day +/- 1 day) were 50, 35, 65 and 80% for the first, second, third and fourth accumulations, respectively (P < 0.05). It was concluded that progesterone production was lower and the oestrous cycles were shorter during the first oestrous cycle and that tactile and visual separation of rams at the beginning of the breeding season might enhance the synchronizing effect towards the end of the breeding season in the fat-tailed Tuj ewes.  相似文献   

10.
Wild common carp (Cyprinus carpio carpio) is a native valuable but threatened species from the south‐eastern Caspian Sea in which the endocrine control of its reproduction has not been studied. The objectives of this research were to study the reproductive strategy and changes in steroid hormones during ovarian development. From October 2009 to June 2010, 65 adult females were caught from the Golestan coast (Iran) and the ovarian histology, and gonadosomatic and hepatosomatic indices (GSI and HSI) were studied. Also, the plasma profiles of steroid hormones including testosterone (T), 17β‐estradiol (E2) and 17α‐, 20β‐dihydroxyprogesterone (DHP) were measured by radioimmunoassay. The GSI increased gradually during sampling times and reached maximum value at the peak of reproduction season, but the HSI decreased during spawning season. All stages of ovarian development, except the stage of Balbiani bodies, were recorded macro‐ and microscopically. Spent fish were caught at six of nine sampling times. The peaks of spawning were at late winter and early spring. The results of this study showed that the majority of wild carp collected during the sampling period displayed asynchronous oocyte development. Plasma T showed no significant differences during sampling times or at different stages of ovarian development. The level of E2 decreased gradually during sampling times reached minimum value at the spawning season, and highest value was recorded at tertiary vitellogenesis stage. The plasma levels of DHP during late winter and early spring were significantly higher than those of other sampling periods and its maximum level associated with oocyte maturation stage.  相似文献   

11.
The present study was undertaken to determine changes in circulating levels of immunoreactive (ir)-inhibin, FSH, LH, estradiol-17beta, progesterone, and testosterone during the ovulatory cycle of Shao ducks. Serial blood samples were taken from two groups of laying ducks for measurement of ir-inhibin, gonadotropins, and steroid hormones at 2 h intervals for 24 h. Plasma concentrations of ir-inhibin did not change significantly during the ovulatory cycle. The highest level of plasma ir-inhibin was observed 6 h prior to ovulation, which coincided with a decreased level of plasma FSH. One FSH surge was found 12 h after ovulation. Estradiol-17beta, progesterone, and testosterone were also determined during the ovulatory cycle. Two peak values were detected for estradiol-17beta 8 h before ovulation and 4 h after ovulation, while progesterone started to increase 4 h before ovulation and reached a peak at ovulation. The highest level of plasma testosterone was detected around the time of ovulation. These results suggest that inhibin may be involved in the control of FSH secretion during the ovulatory cycle. In addition, both LH and progesterone are of importance in the ovulation process of Shao ducks.  相似文献   

12.
Northern fur seals (Callorhinus ursinus) have a distinct life history pattern comprising annual terrestrial breeding and oceanic migration, and the physiological changes associated with these patterns are of particular interest for understanding their environmental adaptations. However, owing to their oceanic distribution, limited information is available on the reproductive physiology of wild individuals during the immature stage and the winter migration period. This study aimed to determine the relationships among the seasonal hormone profiles, body growth, age, and pregnancy using monthly serum samples collected over 3–5 years from two male and two female captive individuals during pubescence and sexual maturation. Small increases in the serum testosterone signaled puberty in males aged 3 and 4 years. Thereafter, males showed considerable increases in testosterone during breeding seasons, indicating sexual maturity. Immature female serum progesterone was maintained at low levels, but after pubescence, females showed an increase in serum progesterone in August, the month next to the peak of delivery, followed by a decrease. In non-pregnant females, progesterone did not increase significantly until the next breeding season, but in pregnant females, they increased again from February to March and then gradually decreased. Immature males increased body mass constantly and reached puberty when their body mass exceeded 20 kg, and they showed seasonal weight fluctuations after puberty. These results provide fundamental information for determining sexual maturity and pregnancy in this species based on sex steroid hormones and body mass measurements.  相似文献   

13.
On investigation of beta-carotene levels in the blood plasma of 9193 cows in the first and second phases of lactation, and in the eight, ninth months, and to the tenth mid-month of their pregnancy showed the same dynamics in beta-carotinaemia development in all groups, with a wave-like tendency to decrease. The lowest beta-carotene values were recorded during the 1985-1986 winter season and in the following 1986 summer season. Beta-carotene levels also remained low during the subsequent winter and summer feeding season. Different beta-carotene concentrations in the blood plasma were repeatedly found in the phases of lactation reproduction cycle. Increases in the milk production and deteriorated reproduction indicators were recorded in the cows at the time of a steep decrease in beta-carotene concentrations in the blood plasma. The causes of decreasing beta-carotene concentrations in the cow blood plasma are discussed.  相似文献   

14.
The aim of this study was to determine onset of puberty in Cameroon Dwarf goats (CDGs) kept as pets in northwestern Croatia by determining progesterone (PGS) and insulin‐like growth factor‐I (IGF‐I) levels in the blood by RIA methods. The first cyclic ovarian activity was estimated according to hormone profiles as determined in CDG in a moderate climate environment. Sixteen female CDG kids were kept in stables with access to pasture which provided space for exercise. The goat kids born in winter (December–January–February), spring (March–April–May), summer (June–July–August) and autumn (September–October–November) were assigned into four groups according to the season of the year of birth (n = 4 in each group). At 75 days of age at the initiation of the study, they weighed between 3.2 and 5.1 kg (4.24 ± 0.53 kg). The onset of ovulatory activity was determined by PGS and IGF‐I serum concentrations every 10 days starting from 75 days to 155 days of age. The onset of puberty in CDG kids occurred on average at 141.15 ± 2.66 days of age, but varied depending on the season of birth. All CDG kids born during summer were in heat by 155 days of age. In the other groups (kids born in autumn, winter or spring), one goat in each group was not in heat. Changes in blood serum PGS and IGF‐I concentrations during prepubertal and pubertal periods could aid in the evaluation of reproductive status and determination of the onset of puberty in CDG during all seasons of the year in a moderate climate region.  相似文献   

15.
An investigation was carried out to assess the effects of weather on the occurrence and magnitude of the periparturient rise (PPR) in trichostrongylid nematode egg output in breeding Dorper ewes. The study was conducted over three breeding seasons on a ranch in the semi-arid area of Kajiado District in Kenya between June 1999 and December 2001. During each breeding season 20 ewes randomly selected from the breeding stock and 20 others selected from the unmated yearlings were monitored for faecal strongyle egg counts every 3 weeks. The lambing seasons were timed to coincide with the onset of the short rains (October–November 1999), the mid-short rains (November–December 2000) and the end of the dry season (September–October 2001). In each season higher egg outputs were recorded in the peri-parturient ewes compared to the unmated yearlings. The highest PPR occurred in September 2001, when lambing coincided with the end of the dry season, possibly as a result of maturation of hypobiotic larvae. The lowest PPR occurred in November 2000 when the onset of lambing coincided with the mid-short rains, possibly owing to low pasture infectivity associated with a long dry spell between January and October of the same year. The results of this study indicate that PPR occurred when lambing coincided with both the wet and the dry seasons. However, the magnitude was greatly influenced by the season when lambing occurred. It was also influenced by resumption of development of hypobiotic larvae and the nutritional status of the ewes. Not only should control of gastrointestinal nematode parasites in this area aim at preventing the occurrence of PPR by treating ewes 2–3 weeks before they are to lamb and during lactation, but the anthelmintic used must also eliminate hypobiotic larvae. In addition, the animals must be given supplementary feeding during this period.  相似文献   

16.
通过对甘州区1997～2006年十年发情授配母牛数的逐月统计分析,以揭示母牛发情随季节、温度的变化规律.结果发现一年中,发情母牛1月所占的比例最小,只有3.5%;9月最高,达14.0%;按季节分布看,12、1、2月所占比例最小,只有全年的12.81%,7、8、9月所占的比例最高,为38.0%,其中8、9月间差异不显著,与7月间差异显著(P＜0.05),与其它各月间差异极显著(P＜0.01),显示母牛发情具有明显的季节性.将月平均温度与发情母牛所占的比例进行相关性分析可知相关系数(r)为0.869,说明温度与母牛发情呈正相关(t＜0.01).  相似文献   

17.
The present study was performed to examine seasonal changes in the fructose concentrations of seminal plasma and glucose and testosterone concentrations of blood plasma over the course of a year (from November 2004 to November 2005) using 5 Suffolk rams. Osmolality of the seminal plasma was also measured. The fructose concentrations in the seminal plasma increased as the breeding season approached, with the maximum in October (179.8 mg/dl) and the minimum in May (6.9 mg/dl), although there were no significant differences during the year. Osmolality of the seminal plasma in February (304 mOsm) was significantly (P<0.05) lower than in January (325 mOsm), July (327 mOsm), and August (325 mOsm). It was also significantly (P<0.05) lower in November (308 mOsm) than in January and August. The blood plasma glucose concentration in October (79.3 mg/dl) was significantly (P<0.05) higher than in January and February (43.2 and 43.7 mg/dl, respectively). The blood plasma testosterone (T) concentrations were significantly (P<0.05) higher in September (8.5 ng/ml) and October (10.2 ng/ml) than in other months. The fructose concentrations in the seminal plasma appeared to be related to the glucose and T concentrations in the blood plasma. These results show that fructose concentrations in the seminal plasma and blood plasma glucose and T concentrations tended to increase during the breeding season, with the highest concentrations in October.  相似文献   

18.
The timing of the onset of puberty, duration of seasonal ovulatory activity, and length of postpartum anestrus were studied by means of blood plasma progesterone concentrations in a flock of European female mouflons (Ovis gmelini musimon) maintained in captivity under natural photoperiod (40 degrees 25'N). Concentrations of progesterone in the peripheral blood were determined by radioimmunoassay in samples collected from the jugular vein twice a week. First ovulations in the breeding season were highly synchronized and occurred in mid-October. In contrast, the cessation of ovulatory cycles showed significant variation among females and extended from February to May, depending on age, with 2-yr-old animals exhibiting the longest anovulatory period (P < 0.01). When lambing occurred within the breeding season (February-April), 12 out of 26 animals had their first ovulation 25 +/- 1.8 days after parturition. The 14 late-lambing females had the first postpartum ovulation delayed until the next breeding season. March/April-born mouflon lambs that reached a minimum threshold body weight (23.8 +/- 0.6 kg) in their first breeding season reached puberty at 8 mo of age. In those with slower growth rates, however, the prepubertal period was extended throughout the first breeding and nonbreeding seasons, reaching puberty during the breeding season of the following year at 19 mo of age and 27 +/- 0.3 kg body weight. Further, attainment of puberty in ewe lambs born in June/July was also delayed until the breeding season of the following year, when animals had reached a threshold body weight at 17 mo of age.  相似文献   

19.
The purpose of present study was to determine annual changes in serum progesterone (P(4)) concentrations and to clarify basic reproductive characteristics, such as breeding season, estrous cycle, and puberty in female bharals (Pseudois nayaur). Blood was collected from 9 female bharals once or twice weekly for approximately one year. Serum P(4) concentrations were determined by radioimmunoassay. Serum P(4) concentrations showed remarkable and cyclic changes between November/December (winter) and May/June (late spring). The mean estrous cycle was 24.9 +/- 0.5 days. Chasing insistently to other females and discharge of mucus from the vulva were observed around the time when the serum P(4) concentrations began to increase. The chasing behavior and discharge of mucus were considered to be external indicators of estrus in female bharals. Serum P(4) concentrations of a pregnant female had non-cyclic changes, and the values remained high. In this study, all 37 deliveries were between April and September, and about 70% of these were concentrated in May and June. The conception month determined on the day of birth was between October and April for all animals, and the most common month was in December (54%). This month corresponded to an early stage of the period when the serum P(4) concentrations changed cyclically. These results indicate that many female bharals become pregnant at the beginning of the breeding seasons and, if they do not become pregnant, the estrous cycle, about 25 days in length, is repeated.  相似文献   

20.
Now, it is well known that in bovines HDL-C act as substrate for ovarian steroidogenesis. The restriction of entry of other lipoprotein parameters is due to ovarian blood barrier, which restricts the entry of other lipoproteins, which are bigger in size. In vitro studies have indicated their role in mediating proliferation of cells. Besides gonadotropin, Growth Hormone (GH) is also gaining importance in the field of reproduction. GH receptors have been localized on the ovaries and follicle of bovines. Further it has been suggested that it can be the direct role of the hormone or it can be mediated through IGF-I. It has been assigned various roles in mediating follicle development, ovulation and corpus luteum maintenance. The river buffaloes are capable of breeding throughout the year, but during certain period of time were found to be more favourable than the others. It has been found that, winter season and hot humid season exhibit two extreme conditions of temperature variation; Hot humid season being unfavourable than the winter season because of high humidity and reasonably high temperature. It has been observed that during June to August months, conception rate and exhibition of estrus behaviour is low. This study was undertaken to analyze different lipoprotein cholesterol parameters namely Total cholesterol (TC), High-density lipoprotein cholesterol (HDL-C), Triglycerides (TG) and Low density lipoprotein cholesterol (LDL-C) in the plasma of cyclic Murrah buffaloes throughout the estrous cycle. The mean plasma concentration (μg/ml) of different lipoproteins during hot humid season were TC 592 ± 40, HDL-C 229 ± 42, TG 345 ± 95, LDL-C 285 ± 94.Where as in winter season their concentrations were 1381.0 ± 31.0, 1793.0 ± 110.0, 511.0 ± 21.0, 608.0 ± 94.0 respectively.

The mean ± SEM circulatory level of GH was low during HH season than during winter (6 ± 2 ng/ml vs. 17 ± 2 ng/ml). During estrous cycle only one peak of GH was exhibited during hot humid season where as three peaks were exhibited during winter season. It can be concluded that winter season is favourable for maintaining physiological levels of hormones and metabolic parameters, which in turn may increase the reproductive efficiency of bovines. During winter season average temperature was 15 ±5 °C. During hot humid season average temperature was 34 ± 3 °C. THI was more than 75%.  相似文献   


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