A survey of Early Pregnancy Losses in West German Thoroughbred Mares

Merkt, H; Gunzel, A.-R.

doi:10.1111/j.2042-3306.1979.tb01359.x

Cited by 45 publications

(28 citation statements)

References 4 publications

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“…However, embryonic death was highest in mares bred in March, and the rate decreased as the breeding season advanced. Breeding after the first ovulation before 20 day postpartum resulted in lower pregnancy rates and embryonic survival than breeding during the second heat postpartum due to the delay in uterine contraction and intrauterine fluid accumulation [9,12,14,17,21]. These results promote the need for careful evaluation of the body condition of mares if they are to be bred at the first estrus postpartum or if they are bred at the beginning of the breeding season.…”

Section: Discussionmentioning

confidence: 96%

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

Yang¹,

Cho

2007

The Journal of Veterinary Medical Science

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ABSTRACT. A total of 384 Thoroughbred mares were investigated to determine and evaluate the features of early embryonic death at nine equine farms on Jeju Island, South Korea, from 2001 to 2003. Overall, 771 matings for 384 mares resulted in 376 pregnancies 15 days after ovulation. Subsequently, 12.2% (46/376) of these early conceptuses were lost within 45 days after ovulation. Furthermore, about three quarters of the 46 embryonic deaths occurred between 16 and 25 days after ovulation. The incidence of embryonic death was highest in the barren (17.2%), more than 15 years old (15.4%), and more than 10 parities (18.2%) groups compared with the other groups (9.1-16.9%). Mares mated in March, April, and during the first estrus postpartum had higher embryonic death rates, (19.6%, 17.2%, and 24.6%, respectively). Mares with abnormal fluid and cysts in the uterus (18.0%) or multiple embryonic vesicles (23.1%) had higher embryonic death rates than those with normal uterine conditions (9.8%) or single embryonic vesicles (10.5%). The condition of mares, such as breeding condition and the environment of the embryo or fetus, are the major factors in relation to occurrence of early embryonic death. KEY WORDS: breeding condition, embryonic death, Thoroughbred, uterine environment.J. Vet. Med. Sci. 69(8): 787-792, 2007 Horses are long-day breeders and have lower reproductive efficiency compared with sheep and cows [32]. The fertility of mares depends on their individual fertility status. Some mares show total fertility rates of 90% if they are highly fertile, while ordinary mares have total fertility rates ranging from 81% to 92%, which are still higher than those of other animals [2,3]. Sullivan et al. [31] reported a fouryear cumulative pregnancy rate of 74% for Thoroughbred breeding, which was lower than the 85% rate for Quarter horses. Bruck et al. [4] stated that 85% of Thoroughbred mares achieve pregnancy and 69.3% of them give birth to live foals. Rose and Hodgson [25] reported that Thoroughbred mares worldwide have a foaling rate ranging from 60% to 70% on average. Davies Morel [7] suggested that the foaling rates of Thoroughbred mares range from 50% to 80%. Thus, Thoroughbred mares have proven low reproductive efficiency despite their high pregnancy rates. Furthermore, high embryonic mortality is cited as the main reason for low reproduction [7,32].Reproductive dysfunction in mares is closely linked to low fertility caused by improper care and maintenance, artificial control of breeding season, and hormonal and genital disorders [5,7]. In addition, the morphology and diameter of the fetus are important factors for pregnancy and embryonic death rate of mares [5,7]. Embryonic death in mares is primarily associated with genetic and environmental factors [3,21,29,32]. Vaginal infections and other uterine abnormalities have a particularly significant impact on premature loss of the fetus by failing to meet the metabolic needs of pregnancy [3,21,29,32]. At the same time, irregular and unbalanced nutrition and psycholog...

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Section: Discussionmentioning

confidence: 96%

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

Yang¹,

Cho

2007

The Journal of Veterinary Medical Science

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“…Pregnancy rates in this heat are lower than in subsequent heats [Caslick, 1937;Jennings, 1941;Tram, 1950;Ginther, 1979;Merkt & Gunzel, 1979;Lieux, 1980]. This probably happens because uterine involution and endometrial regeneration are not complete when foal heat occurs [Tolksdorff, 1976].…”

Section: Introductionmentioning

confidence: 99%

Use of Methylergonovine Maleate and Cloprostenol during Uterine Involution to Improve Conception Rates of Foal Heat1

Mattos

Rocha

Zimmer

et al. 1995

Biology of Reproduction

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The use of methylergonovine maleate and cloprostenol was tested during uterine involution in mares of different ages to determine whether these treatments could increase pregnancy rates. A total of 311 Thoroughbred mares from Southern Brazil that had experienced normal parturition and given birth to live foals was studied. After parturition, mares were submitted to clinical examination and, if necessary, to vulvoplasty. At that time, mares were randomly assigned to one of the following groups: GI-methylergonovine maleate (n = 77); Gil-cloprostenol (n = 82); GUI-control group (n = 152). Mares were mated every other day after a preovulatory follicle (> 40 mm) was detected. Pregnancy diagnosis was made on Days 18 and 42 postovulation. There were no significant differences in pregnancy rates among groups. Average number of days between parturition and ovulation was 11.8 ± 3.4 (GI), 13.2 ± 4.5 (Gil) and 13.2 ± 4.0 (GUI). There was no relationship between ovulation day and pregnancy rate, but a significant shortening of the parturition-ovulation interval was detected in GI (p < 0.05). Pregnancy rate of mares in GUI with ages less than 10 yr was significantly greater than that of older mares (p < 0.05). This difference was not detected in GI and Gil.

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“…Recently, high pregnancy rates have been reported also for mares bred in foal heat (Camillo et al 1997: 72%;Arrott et al 1994: 82%). Merkt and Günzel (1979) reported a higher pregnancy loss rate for lactating mares than for non-lactating mares: 17% vs. 6%. In many other studies the pregnancy loss rates of mares conceiving in foal heat as compared to foaling mares that conceived in subsequent oestruses have not been significantly different (Lieux 1980: 16% vs. 14%;Loy 1980: 13% vs. 12%).…”

Section: Pregnancy Rate and Pregnancy Loss Ratementioning

confidence: 93%

The post partum mare

Katila¹,

Reilas²

2001

PHK

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SummaryBecause of the long gestation period, a mare should conceive soon after foaling in order to foal every year. Although lactation is high and uterine involution incomplete, the mare is able to conceive during the first post partum (p.p.) oestrus. Normal delivery causes little damage to the uterine epithelium. The numerous microcaruncles disappear rapidly by degeneration and resorption. A tremendous decrease in uterine size takes place after foaling, particularly during the first week after foaling. By 3 weeks p.p. the uterus has returned to the pregravid size. For several days following parturition the uterus is extremely firm upon transrectal palpation, probably because of the extensive p.p. oedema. Intrauterine fluid collections are largest 1 to 2 d p.p. and decrease gradually between days 4 and 7; no fluid is normally detected after day 16. The process of bacterial elimination is not completed in all mares during the foal heat, but the incidence of positive cultures is much lower than shortly after foaling. Neutrophils are a common finding in uterine swabs <6 d p.p., and some mares show low numbers of neutrophils still during the foal heat. The uterine environment changes markedly even after the first p.p. ovulation. After day 16, protein and enzyme levels in uterine lavage fluid of p.p. mares had decreased to normal levels, showing that the secretory function had been restored to the pregravid state. Trypsin inhibitor capacity, lysozyme levels and neutrophil numbers in uterine lavage fluid during foal heat tended to be higher in mares from which no embryos were recovered, suggesting that a persisting inflammation at the end of foal heat may be the best explanation for lowered pregnancy rates. The presence of ultrasonically detectable intrauterine fluid has also been show to decrease foal heat pregnancy rates. Keywords:horse, uterus, involution, inflammation, foal heat

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A survey of Early Pregnancy Losses in West German Thoroughbred Mares

Cited by 45 publications

References 4 publications

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

Factors Concerning Early Embryonic Death in Thoroughbred Mares in South Korea

Use of Methylergonovine Maleate and Cloprostenol during Uterine Involution to Improve Conception Rates of Foal Heat1

The post partum mare

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