Follicular and steroid hormone changes in Arabian mares in the postpartum period

In this study, the aim has been to characterize the profiles of progesterone, estradiol and follicular changes during postpartum period from parturition to first postpartum ovulation. Jugular venous blood was taken daily for progesterone and estradiol assay until first postpartum ovulation. The diameters of the follicles of the ovaries were recorded. The mean progesterone and estrogen concentrations markedly decreased (p<0.05) during the 48h after parturition. No correlation was observed between estradiol concentrations and the diameter of the largest follicle whereas a negative correlation was present between the number of follicles smaller than 20mm and the number of follicles larger than 20mm on the third and fourth days after postpartum.     

Cyclicity and gestation length ofMacaca fascicularis

Menstrual cycle records were kept on all of the females in the colony for a period of 14 months. The mean cycle length was 30.8 days; the median, 33 days; and, the mode, 28 days. Cycles ranging from 27 to 32 days in length comprised 66.4% of all cycles. Regular cycles were scored on the basis of menses beginning within 2 days of a projected date based on an average of 6 previous cycles. Regular cycles were observed in 6.24% of the cases. The mean cycle length for regular cycles was 29.2 days. Forty-five percent of all females had regular cycles at least 70% of the time. The duration of menstrual flow for 150 cycles averaged 2.8 days. Menses ranged from 1 to 8 days in length, with 90.7% of the cases ranging from 1 to 4 days in length. For a given duration of menses, the percentage of cases of light flow increased as the end of the menstrual period was reached. The mean gestation length of 3 pregnancies was 164.4 days, with implantation bleeding beginning on day 19 of pregnancy and lasting from 4 to 9 days.This work supported by National Institute of Child Health and Human Development, Center for Population Research Contract No. 70-2061; USPHS Grant No. 5-PO6-RR 00366-04, to the Center for Laboratory Animal Resources, and, NIH Career Development Award No. 1-K4-HD35, 306-01. Journal Series Article No. 5668. Approved by the Director, Michigan State University Agricultural Experiment Station.     

Analysis of several factors of variation of gestation loss in breeding mares

The files for ultrasound diagnosis of gestating mares belonging to the French equine herd recorded for 3 consecutive years were joined with the files for foal birth of these same mares, allowing the statistical analysis of factors of pregnancy loss. For 28 872 positive diagnoses of gestation, 2898 losses were recorded, that is, a global rate of gestation interruption of 9.12%. The etiology of these interruptions is mainly extrinsic: the year and month of insemination, as well as region for climatic reasons. The intrinsic causes that are implicated are breed of the father (heavy breeds except the hypermetric ones lose fewer pregnancies than warm-blooded breeds), age of the mother (losses are lower in mares of 7 to 10 years of age) and status (mares with foals have fewer pregnancy losses than mares not having foaled the previous year), as well as fetuses with consanguinity (when this increases, the pregnancy losses increase as well). However, the additive genetic effect is extremely low; it corresponds to heritability below 5% and few effects of the environment, common to the offspring of the same mare, were identified. This therefore gives little hope of being able to select against the ‘gestation loss’ trait.     

Factors affecting gestation length in dairy cattle

Data were collected through a special record keeping system for 2,254 herds that used artificial insemination, 37% of which were enrolled in Dairy Herd Improvement Associations. Information was available on a total of 35,162 gestations, consisting of 24,367 Holstein, 5,849 Guernsey, 2,872 Jersey, 1,667 Ayrshire and 407 Brown Swiss pregnancies resulting in single births plus 930 multiple births. Breeds, twinning, sex of calf, parity of the cow and time of day on which estrus occurred were associated with differences in gestation length. Month of insemination had no effect. Mates and sires of the cows both affected gestation length slightly, but significantly. Selection of sires for high milk production of their daughters over a 23-year period appears to have had little, if any, effect on gestation length, as the mean gestation length has increased only one day, from 278 to 279 days for Holsteins during that time.     

A genome-wide association study of direct gestation length in US Holstein and Italian Brown populations

Direct gestation length influences economically important traits in dairy cattle that are related to birth and peri-natal survival of the calf. The objective of this study was to identify single nucleotide polymorphisms (SNPs) that are significantly associated with direct gestation length through a genome-wide association study. Data used in the analysis included 7,308,194 cow gestation lengths from daughters of 4743 United States Holstein sires in the Cooperative Dairy DNA Repository population and 580,157 gestation lengths from 749 sires in the Italian Brown population. Association analysis included 36,768 and 35,082 SNPs spanning all autosomes for Holstein and Brown Swiss, respectively. Multiple shrinkage Bayesian was employed. Estimates of heritability for both populations were moderate, with values of 0.32 (±0.03) and 0.29 (±0.02) for Holstein and Brown Swiss, respectively. A panel of SNPs was identified, which included SNPs that have significant effects on direct gestation length, of which the strongest candidate region is located on chromosome 18. Two regions not previously linked to direct calving ease and calf survival were identified on chromosome 7 and 28, corresponding to regions that contain genes related to embryonic development and foetal development. SNPs were also identified in regions that have been previously mapped for calving difficulty and longevity. This study identifies target regions for the investigation of direct foetal effects, which are a significant factor in determining the ease of calving.     

Seasonal changes in the red blood cell indices in Arabian brood mares and their foals

In 34 pure-bred Arabian horses, divided into four groups (Gr. I, 10 pregnant mares; Gr. II, seven barren mares; Gr. III, 10 foals born in 1981; Gr. IV, seven foals born in 1982), seasonal changes in haemoglobin level, haematocrit value, sedimentation rate, red blood cell number and diameter, percentage of erythroblasts and reticulocytes, and index F were studied. Seasonal cyclicity was found in all groups in the haemoglobin level, haematocrit value and RBC diameter. It was also found in the sedimentation rate (PCV) and in index F, but not for the youngest foals (Gr. IV). For the RBC number the cyclicity is given in both groups of foals, and the erythroblast and reticulocyte percentage only in the older foals (Gr. III). Out of eight indices studied cyclicity was found in all foals in Gr. III, in five of the mares in Groups I and II, and in four of the youngest foals in Gr. IV. There is no difference in the cyclicity of indices studied between pregnant and barren mares.     

FSH and LH activity of PMSG from mares at different stages of gestation

Blood was collected from each of four mares at approximately 60, 90 and 120 days of pregnancy. Pregnant mare serum gonadotrophin (PMSG) was prepared in a relatively impure form from each serum sample. Biological activities of FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) were determined for each sample. FSH activity was greatest at 60 days of gestation and was reduced by day 90; this reduction persisted through day 120. LH activity was highly variable among mares at 60 and 120 days, and variability and mean values were lowest at 90 days. The mean ratio of FSH to LH was greatest at 90 days. The mean ratio of FSH to LH was greatest at 90 days and somewhat lower at both 60 and 120 days. The results suggest that the composition and biological activity of PMSG, as prepared and assayed by these procedures, may vary during gestation as well as among mares.     

Factors affecting gestation length in the Thoroughbred mare

In order to assist in the accurate prediction of the timing of parturition in the mare true gestation length, along with the potential effect of a number of factors, was investigated. Data from 433 Thoroughbred foal pregnancies were used. Sequential ultrasonic scanning allowed the true gestation length (fertilisation-parturition) to be ascertained, as apposed to previous work, which used the mating-parturition interval. An average gestation length of 344.1 +/- 0.49 days was evident. Colt foal pregnancies were significantly (P < 0.001) longer (346.2 +/- 0.72) than fillies (342.4 +/- 0.65). Month of birth had a significant effect on gestation length in all foals (P < 0.001). With foals born in January having the shortest gestation lengths and those born in April the longest. Mare age, year of birth, stallion age, stud farm and the interval between ovulation and mating had no significant effect. It is concluded that (i) the gestation length range (315-388 days), all resulting in viable foals is noteworthy and of clinical importance when considering the classification of dysmaturity in foals, (ii) mares carrying colt foals due to be born in the middle of the breeding season (April) are likely to have the longer gestation lengths.     

The source of the 5-alpha-pregnanes that occur during gestation in mares.

[1,2,6,7-3H]Progesterone was injected into the uterine artery of umbilical vein of 4 pregnant Ponies to determine whether 5 alpha-pregnane-3,20-dione (DHP), 20 alpha-hydroxy-5 alpha-pregnan-3-one (20 alpha-ol), and 3 beta-hydroxy-5 alpha-pregnan-20-one (3 beta-ol) are produced by the placenta, fetus, or mare during late gestation. Plasma samples were collected from indwelling catheters in the uterine artery and vein and the umbilical artery and vein at frequent intervals until 6 h after isotope injection. The plasma samples were extracted with organic solvents and the respective pregnanes were isolated by thin-layer chromatography. Mean plasma levels of radioactive DHP in the umbilical vein were greater (P less than 0.05) than those in the umbilical artery but were similar to those in the uterine artery and vein. Plasma levels of radioactive 20 alpha-ol in the umbilical artery and vein were less (P less than 0.05) than those in the uterine artery but similar to those in the uterine vein. Levels of radioactive 3 beta-ol in the umbilical artery were greater (P less than 0.05) than those in uterine artery and vein and similar to those in the umbilical vein. We suggest that DHP was produced by the placenta and a maternal source, that 20 alpha-ol was primarily of maternal origin, and that 3 beta-ol was formed primarily by the fetus.     

Ontogeny of uteroplacental progestagen production in pregnant mares during the second half of gestation

In pregnant mares during late gestation, little, if any, progesterone (P4) is found in the maternal circulation. Hence, quiescence of the equine uterus is believed to be maintained by metabolites of pregnenolone and P4 known as progestagens, which are produced by the uteroplacental tissues. However, little is known about the ontogeny, distribution, or actual rates of uteroplacental progestagen production in pregnant mares and their fetuses during the second half of pregnancy. Therefore, the present study measured the rates of uteroplacental uptake and output of eight specific progestagens in chronically catheterized, pregnant pony mares from 180 days to term. No significant uteroplacental uptake of any of the eight individual progestagens was observed from the uterine circulation. In contrast, significant uteroplacental uptake was observed for five of the eight individual progestagens from the umbilical circulation, and the uptakes increased toward term. The major uteroplacental progestagen outputs were 5 alpha-pregnane-3,20-dione (5 alphaDHP) and 20 alpha-hydroxy-5 alpha-pregnan-3-one (20 alpha 5P). These were released into both the umbilical and uterine circulations at rates that increased toward term. The majority of the total uteroplacental 20 alpha 5P output was distributed into the uterine circulation at all gestational ages studied. In contrast, distribution of the total uteroplacental 5 alphaDHP output switched from preferential delivery into the uterine circulation before 220 days of gestation to release predominantly into the umbilical circulation after 260 days. These findings demonstrate that uteroplacental progestagen production changes during the second half of gestation, which may have important implications for the maintenance of pregnancy and the onset of labor in the mare.     

Effects of bromocriptine and perphenazine on prolactin and progesterone concentrations in pregnant pony mares during late gestation

Pregnant pony mares in Group A (n = 4) received i.m. injections at 07:00 and 17:00 h of 0.8 mg bromocriptine/kg body weight 0.75 per day beginning on Day 295 of gestation and continuing until parturition. Group B (n = 4) was treated similarly, but perphenazine was administered orally at 0.375 mg/kg body weight twice a day beginning on Day 305 of gestation and continuing until parturition. Mares in Group C (n = 3) received i.m. injections of saline. Mean plasma prolactin and progesterone concentrations were greater (P less than 0.05) for mares in Group C than in Groups A and B from 295 to 309 days of gestation. From 305 days of gestation, plasma prolactin and progesterone concentrations were greater (P less than 0.05) in Group B and C than in Group A mares. Progesterone and prolactin concentrations increased over this period for Group B and Group C mares, but remained constant in Group A mares. From 10 days pre partum through foaling, mares in Group A had lower progesterone (P less than 0.05) and prolactin (P less than 0.01) concentrations than Group B and C mares. All mares in Group A were agalactic at foaling, while all mares in Groups B and C had normal milk secretion. Gestation was longer (P less than 0.05) in Group A than in Group C mares. In Group A, 2 mares retained the placenta for greater than 3 h, 3 mares had dystocia and all 4 mares had thickened, haemorrhagic placentae.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors affecting length of gestation and birth weight of Nili-Ravi buffaloes

This study was conducted to determine the effects of various factors on gestation length and calf birth weight of Nili-Ravi buffaloes in Pakistan. Records were analyzed from 421 uneventful calvings by 274 buffaloes inseminated artificially from 1980 to 1984. Gestation averaged 308.7±0.4 days and ranged from 275 to 346 days in length. Most (57.2%) buffaloes calved from 305 to 314 days after insemination. Calf birth weight, sire of calf, month of breeding, and month of calving accounted for significant amounts of variation in lengths of gestation. Gestation length changed quadratically with calf birth weight. Buffaloes producing calves weighing about 35 kg had the shortest (about 308 days) gestation period, and buffaloes producing calves weighing either more or less than 35 kg had longer gestation periods. Calf birth weight averaged 38.2 ± 0.2 kg and ranged from 17 to 48 kg. Bull calves were heavier at birth than were heifer calves (39.0 vs. 37.5 kg). Calf birth weight increased quadratically with body weight of the dam at calving. Heavier dams produced heavier calves, and body weight of the dam at calving increased with age of the dam at calving. This study indicates that sires, dams and months of breeding could be selected to help control gestation length and birth weight of Nili-Ravi buffaloes.     

Relation between atmospheric pressure fluctuations and swine gestation length variation

The relation between atmospheric pressure fluctuations and variation in the length of gestation in domestic swine was studied empirically using factor analysis. Atmospheric pressure's time-rate-of-change was used as a gross indicator of weather changes. Virtually no evidence was obtained to support the existence of any meteorotropic relationship between atmospheric pressure fluctuations and variation in domestic swine gestation length.

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Zusammenfassung Mit der Faktorenanalyse wurde die Beziehung zwischen Schwankungen des Luftdrucks und der Dauer der Trächtigkeit beim Hausschwein empirisch untersucht. Als grober Indikator für Wetteränderungen wurde die zeitliche Luftdruckänderung benutzt. Er wurden keine Anzeichen gefunden, die das Vorhandensein irgendeiner meteorologischen Beziehung zwischen den Schwankungen des atmosphärischen Luftdrucks und denen der Dauer der Trächtigkeit beim Hausschwein wahrscheinlich machen würden.

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Resume On a recherché, au moyen de l'analyse factorielle,les relations empiriques possibles entre les variations de la pression atmosphérique et la durée de gestation du porc domestique. On a utilisé, en première approximation, les fluctuations de la dite pression comme indicateur des changements de temps. On n'a cependant trouvé aucun signe laissant présumer une relation météorotropique entre les variations de la pression et la durée de gestation du porc domestique.

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Journal Paper No. 3297, Purdue University Agricultural Experiment Station. The authors gratefully acknowledge the counsel of Dr. J.E.Kutzbach, Center for Climatic Research and Department of Meteorology, University of Wisconsin,Madison,Wisconsin, USA, during this study while Lewis and Curtis were CIC Visiting Fellows in Biometeorology at that institution.     

The effect of oxytocin and PGF2alpha on the uterine involution and pregnancy rates in postpartum Arabian mares

In this study, the effects of oxytocin and an analog of prostaglandin (cloprostenol) on the uterine involution and pregnancy rates were investigated. Mares received 3 ml of 0.9% NaCl in Group C (n=10), 30 IU/mare of oxytocin in Group O (n=10) and 250 microg/mare of cloprostenol in Group P (n=10) within 12h after parturition. The gravid uterine horn's cross-sectional diameter was measured by ultrasonography. The mean uterine diameters did not differ significantly between the treatment (O and P) and the control (C) groups (p>0.05). The difference between the postpartum ovulation periods (Group C: 12.6+/-0.72 days, Group O: 15+/-1.33 days, Group P: 14.6+/-1.11 days), the pregnancy rates at foal heat (Group C: 60%, Group O: 60%, Group P: 80%) and the embryonic death rates at foal heat (Group C: 33.3%, Group O: 16%, Group P: 25%) were not found to be statistically significant between the treatment and the control groups. The mean progesterone concentrations were similar in all groups and decreased continuously from parturition to until foal heat (Group C: from 2.43+/-0.24 to 0.66 ng/ml, Group O: from 3.07+/-0.6 to 0.27+/-0.27 ng/ml and Group P: from 2.8+/-0.44 to 0 ng/ml) (p>0.05). In conclusion, it was decided that the oxytocin and PGF2alpha treatments performed on the mares with the purpose of stimulating involution had no effect on the duration of parturition-first ovulation, the shrinkage of the uterus diameter, the pregnancy and embryonic death rates.     

Seasonal changes in blood serum protein fractions and in activity of AspAT and AlAT in Arabian brood mares and their foals

In 34 pure breed Arabian horses divided into four groups (Gr. I--10 pregnant mares, Gr. II--7 barren mares, Gr. III--10 foals born in 1981, Gr. IV--7 foals born in 1982) seasonal changes in total blood serum protein, its electrophoretic fractions and the activity of AspAT and AlAT were studied. Seasonal cyclicity was found in all groups in the amount of total serum proteins, and alpha 2- and beta 1-globulin fractions. Cyclicity was found in the level of albumin and activity of AspAT in three groups, not Gr. II, and in gamma-globulin, not Gr. IV. beta 2-globulin and AlAT cyclicity was found in two groups and alpha 1-globulin cyclicity was found only in Gr. II. Out of nine indices studied, cyclicity was found in eight of them in pregnant mares, Gr. I; in seven in older foals, Gr. III; in six in the young foals, Gr. IV; and in five in barren mares, Gr. II.     

Genetic blood markers in Arabian, Barb and Arab-Barb horses in Morocco

Gene frequencies at 16 blood group and protein polymorphism loci (A, C, D, K, P, Q, U, Al, Gc, Es, A1B, Tf, PGD, PGM, GPI and Pi) are given for three horse breeds in Morocco (Arabian, Arab-Barb and Barb). These data are used to calculate average heterozygosity (h), Nei's standard genetic distance (D_N) and probability of exclusion (PE). Variability expressed as the average heterozygosity was lower in the Arabian (0.330 ± 0.066), while it was higher and almost the same in the Arab-Barb (0.413 ± 0.071) and the Barb (0.414 A ± 0–070). The shortest genetic distance was found between Barb and Arab-Barb. The 16 loci used are at least 95% effective for recognizing incorrect paternity in these breeds. The Barb and Arab-Barb genetic profiles obtained showed the rare variants interesting perhaps in the context of European and American breeds: notably D^cfgkm, D^dekl, Es-N, Tf-A and Pi-W.