Reproductive efficiency of Thoroughbred and Standardbred horses in north‐east Victoria

Nath, L.; Anderson, GA; McKinnon, AO

doi:10.1111/j.1751-0813.2010.00565.x

Cited by 71 publications

(91 citation statements)

References 22 publications

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“…; Nath et al. ). Coverings of young (3–8 years), middle aged (9–13 years), older mares (14–18 years) and mares aged 19 years and older resulted in per cycle pregnancy rates of 72%, 68%, 59% and 47%, respectively, with the oldest mares 2.87 times more likely to be not pregnant per cycle compared with the youngest mares.…”

Section: Discussionmentioning

confidence: 98%

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

Lane

Bijnen

Osborne

et al. 2016

Reprod Domestic Animals

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To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4-15 years) had bred 2385 mares (mean age 9.4 years; range 3-24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to evaluate mare factors, including mare age, reproductive status, month of foaling, dystocia, month of cover, foal heat, cycle number, treatments, walk-in status and stallion factors including stallion identity, stallion age, shuttle status, time elapsed between covers and high stallion usage on the per cycle pregnancy rate and pregnancy loss. Old age (p < 0.001) and cover within 20 days post-partum (p < 0.003) were associated with lowered pregnancy rates. High mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss. Uterine inflammation or infection, if appropriately treated, did not affect fertility. Only high usage of stallions (used more than 21 times in previous week) was associated with lowered (p = 0.009) pregnancy rates. However, shuttle stallions were more likely to have increased (p = 0.035) pregnancy survival, perhaps reflecting a bias in stallion selection. In conclusion, mare age exerted the greatest influence on fertility; nonetheless, thoroughbreds can be effectively managed to achieve high reproductive performance in a commercial setting.

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Section: Discussionmentioning

confidence: 98%

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

Lane

Bijnen

Osborne

et al. 2016

Reprod Domestic Animals

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“…Nath et al . reported significantly fewer embryonic losses between 13 and 45 days of gestation in mares diagnosed with multiple pregnancies that underwent manual elimination (4.6%) than in singleton pregnancies (7.5%), leading these authors to conclude that manual reduction should not adversely affect the remaining conceptus within 45 days of gestation . Given that the study by Nath et al .…”

Section: Discussionmentioning

confidence: 97%

Factors affecting live foal rates ofThoroughbred mares that undergo manual twin elimination

Schnobrich

Riddle

Stromberg

et al. 2013

Equine Veterinary Journal

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SummaryReasons for performing study: Mares diagnosed with twin vesicles at 13-17 days after ovulation commonly have one of 2 vesicles manually reduced. It is not known whether vesicle location (adjacent vs. nonadjacent), mare age, mare reproductive status, parity, month of breeding or mare plasma progesterone concentration affects live foal rates. Objectives: To determine factors associated with a positive outcome (live foal) in mares undergoing manual twin reduction between 13 and 17 days post ovulation when performed by a single operator. Study design: Retrospective case-control study. Methods: Breeding records and the Jockey Club records of registered Thoroughbreds were used to evaluate factors affecting the outcome of pregnancies in mares undergoing twin elimination and mares with singleton pregnancies. Thoroughbred mares with twin pregnancies (n = 129) were matched by age, parity, farm location and month bred with mares diagnosed with a singleton pregnancy (n = 127). The effects of location of embryonic vesicles, mare age, reproductive status, parity, month of breeding, vesicle size and plasma progesterone concentration at pregnancy diagnosis on live foal rate were examined. Results: Position of embryonic vesicles at time of manual elimination, parity and month bred had no effect on live foal rate. Live foal rates in mares >9 years of age were lower (71.8%) than in all mares Յ9 years (87.1%; P<0.05). Mares >9 years of age that had a twin reduced lost more pregnancies (34.8%) than age-matched control mares (20.0%; P<0.005). Mean plasma progesterone concentration of twin-reduced mares was greater than in control mares when compared on the same day post ovulation. Plasma progesterone concentrations did not differ between mares that lost their pregnancy and those that delivered a live foal. Conclusions: Mare age of >9 years is associated with decreased pregnancy rate after twin reduction. Potential relevance: Furthering the understanding of factors that affect live foal outcome following manual twin elimination in mares.

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“…This represents an improvement over the previously reported conception rates (ranging between 0 and 13% [1,2]) obtained using sex-sorted, cryopreserved stallion sperm. Around 7.5% of all conceptions in mares ('natural' or AI) result in EED [36], with 63% of these losses occurring between 15 and 45 days after ovulation. It has previously been shown that cold storage of stallion semen for 12-24 h prior to freezing is not detrimental to sperm motility or to conception rates as assessed by ultrasonography 15 days after insemination [4,[24][25][26] and that liquid storage of sperm either prior to or following sorting also does not appear to be appreciably detrimental to conception rates [4,27] or sperm quality [28].…”

Section: Discussionmentioning

confidence: 99%

Field fertility of liquid stored and cryopreserved flow cytometrically sex‐sorted stallion sperm

Gibb

Grupen

Maxwell

et al. 2016

Equine Veterinary Journal

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Reproductive efficiency of Thoroughbred and Standardbred horses in north‐east Victoria

Cited by 71 publications

References 22 publications

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

Factors affecting live foal rates ofThoroughbred mares that undergo manual twin elimination

Field fertility of liquid stored and cryopreserved flow cytometrically sex‐sorted stallion sperm

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