Puberty and growth rate in thoroughbred fillies.
Abstract: We measured progesterone and estradiol levels from birth to the beginning of adult life in 10 Thoroughbred fillies from the Equilia Stud Farm in Avaré SP, Brasil. The animals were measured and weighed monthly for the determination of body development and of a possible correlation between the rate of weight and height gain and the onset of detectable sex hormone levels. Jugular blood was collected twice a week and stored at -20 degrees C until assay of progesterone by a solid phase RIA with a sensitivity of 0.32 nmol L and of estradiol by liquid phase RIA adapted to low levels (3.67 pmol L ). The fillies were born with high serum levels of both hormones, which fell to undetectable levels by the first week of life. A variation in growth rate was observed, with the highest levels occurring from birth to the 3rd month of life, followed by a reduction until 15 mo of life, when fast growth was resumed. The monthly weight gain was 1.5% when the fillies reached puberty and 5.4% during the next month, (P 0.05). The month of onset of puberty was the month of lowest weight gain in the life of the fillies, and it coincided with the highest insolation period. In conclusion, horses, like all other developed vertebrates, have a double pattern of development, with the acceleration observed at puberty depending on sex steroids, which in turn coincides with the highest insolation period. Gonadal activity characterized by serum progesterone levels was low from birth to the onset of puberty. After puberty the progesterone cycles were similar to those of adult animals with a mature hypothalamic-gonadal axis.
Publication Date: 2006-05-27 PubMed ID: 16728154DOI: 10.1016/s0093-691x(97)00275-6Google Scholar: Lookup
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- Journal Article
Summary
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This study is about the relationship between the onset of puberty, growth rate, and hormone levels in ten Thoroughbred fillies from birth to adulthood. The researchers found that the fillies’ growth rates were influenced by their hormone levels, and they observed a double pattern of development, with an acceleration at puberty due to sex steroids.
The Research Method
- Researchers monitored ten Thoroughbred fillies from the Equilia Stud Farm in Avaré SP, Brasil, from birth until they reached adulthood.
- The fillies were measured and weighed on a monthly basis to monitor their body development.
- This was done to identify any correlations between the rate of weight and height gain with the onset of detectable levels of sex hormones.
- The fillies’ jugular blood was collected twice a week and stored at -20°C for later analysis of progesterone and estradiol levels.
Findings
- The fillies were discovered to have high levels of progesterone and estradiol at birth, which declined to undetectable levels within their first week of life.
- A fluctuation in their growth rate was noticed, with the fastest growth happening from birth until the fillies were three months old. This followed a decrease until the age of 15 months, when a rapid growth period started again.
- During the month the fillies reached puberty, their weight gain was 1.5%, which increased to 5.4% in the following month. This suggests the onset of puberty initiates a faster growth period.
- Contrarily, the parameters of skeletal growth did not change once the progesterone production began at noticeable levels, typically marked as the beginning of puberty in fillies.
- The month when the fillies started puberty showed the lowest weight gain, coinciding with the most extended daylight period.
Conclusion
- The study found that horses, like other developed vertebrates, follow a double pattern of development. This includes an acceleration at puberty, which Depend on sex steroids. An interesting correlation was found between this growth spurt and the highest daylight period.
- These findings suggest that the onset of puberty plays an integral role in a filly’s growth and development with a relationship to hormone levels.
- The serum progesterone levels were found to be low from birth until puberty. After puberty, the progesterone cycles mirrored those of mature animals with a fully developed hypothalamic-gonadal axis. The study provides valuable insight into the growth and developmental cycles of young female thoroughbreds.
Cite This Article
APA
Nogueira GP, Barnabe RC, Verreschi IT.
(2006).
Puberty and growth rate in thoroughbred fillies.
Theriogenology, 48(4), 581-588.
https://doi.org/10.1016/s0093-691x(97)00275-6 Publication
Researcher Affiliations
- Animal Physiology, UNESP, Araçatuba-SP 16050-680, Brasil.
Citations
This article has been cited 1 times.- Arango-Sabogal JC, Mouncey R, de Mestre AM, Verheyen K. Date of birth and purchase price as foals or yearlings are associated with Thoroughbred flat race performance in the United Kingdom and Ireland. Vet Rec Open 2022 Dec;9(1):e43.
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