Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analyses.
Abstract: To describe the reproductive performance of a population of Thoroughbred mares on stud farms in the Waikato region of New Zealand. Methods: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares contributed 2007 mare years and 3,402 oestrous cycles over the three breeding seasons. Mares were served by 87 individual stallions. Results: The mean first-cycle pregnancy rate (FCPR) was 53.6%, the end-of-season pregnancy rate (SPR) was 85.3% and the foaling rate was 80.2%. There were significant differences amongst farms for FCPR (range 47.3-68.2%; p<0.01), SPR (range 81.4-92.6%; p<0.001) and foaling rate (range 77.8-90.1%; p<0.001). There were significant differences amongst stallions in their FCPR (range 38-74%; p<0.001) and SPR (range 72-97%; p<0.001).The proportion of pregnancies lost between day 14-16 and day 42 of gestation was 5.5% and the proportion of pregnancies lost between day 42 and term was 3.0%. Mares older than 14 years of age and barren mares had the highest pregnancy loss rates. Of all pregnancies diagnosed at 14-16 days, 12.9% were multiple pregnancies. The length of the breeding season was relatively short with 87.3% of services occurring in the 91-day period between 1 September and 30 November. Conclusions: The reproductive performance of Thoroughbred mares in the Waikato region of New Zealand was similar to that reported from other major Thoroughbred breeding countries. Although the per-cycle pregnancy rates in this study were lower than those reported in some studies, the foaling rate was similar to previous reports and this was achieved during a relatively short breeding season.
Publication Date: 2012-08-21 PubMed ID: 22905831DOI: 10.1080/00480169.2012.693039Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the reproductive performance of Thoroughbred mares in the Waikato region of New Zealand over three breeding seasons, with the final results comparable to similar studies in other major Thoroughbred breeding countries.
Study Outline and Methodology
- This is a prospective cohort study that is focused on the reproductive performance of Thoroughbred mares in the Waikato region of New Zealand.
- Five different stud farms participated in the study, which spanned over three consecutive breeding seasons from 2006 to 2008.
- Different parameters taken into consideration range from the total number of mares (1,482), the total number of mare years (2007), the total number of oestrous cycles (3,402), and the total number of stallions that were involved in servicing the mares (87).
Study Results
- The first-cycle pregnancy rate (FCPR) was found to be an average of 53.6%, while the end-of-season pregnancy rate (SPR) averaged at 85.3%. The foaling rate was 80.2%.
- Significant variances were observed among the different stud farms especially concerning the FCPR which ranged from 47.3-68.2% (p<0.01), SPR (ranged from 81.4-92.6%, p<0.001), and the foaling rates (ranged from 77.8-90.1%, p<0.001).
- Furthermore, there were significant differences amidst the individual stallions as well regarding their FCPR (ranged between 38-74%, p<0.001) and SPR (ranging from 72-97%, p<0.001).
- The study highlights the rate of pregnancy losses between day 14-16 and day 42 of gestation (at 5.5%), and from day 42 to term (at 3.0%).
- Mares that were older than 14 years and barren mares had the highest pregnancy loss rates amongst all.
- Additionally, a notable percentage (12.9%) of all pregnancies diagnosed from day 14 to 16 was multiple pregnancies.
- An important observation made was the relatively short length of the breeding season, with 87.3% of services occurring in the 91-day period between 1 September to 30 November.
Conclusion
- The reproductive performance of the Thoroughbred mares in the Waikato region of New Zealand was similar to reported performances from other leading Thoroughbred breeding nations.
- Even though the initial per-cycle pregnancy rates appeared lower than most other reports, the foaling rates were within the same range, particularly given the short duration of the breeding season.
Cite This Article
APA
Hanlon DW, Stevenson M, Evans MJ, Firth EC.
(2012).
Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analyses.
N Z Vet J, 60(6), 329-334.
https://doi.org/10.1080/00480169.2012.693039 Publication
Researcher Affiliations
- Matamata Veterinary Services Ltd, 26 Tainui St, Matamata, New Zealand. dhanlon@matavet.co.nz
MeSH Terms
- Aging
- Animals
- Cohort Studies
- Female
- Horses / physiology
- New Zealand
- Pregnancy
- Pregnancy Rate
- Pregnancy, Animal
- Prospective Studies
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