Growth curves from birth to weaning for Thoroughbred foals raised on pasture.
Abstract: To mathematically describe the growth of a population of Thoroughbred foals reared on pasture in New Zealand from birth to weaning. Methods: Twice-monthly liveweight data (including birthweight; BW) from 218 foals (98 colts and 120 fillies) born over a 6-year period, and reared on four different pasture types, were available for analysis. Data truncated to the time of weaning (107-217 days old) provided 3,200 data points. After testing for non-linearity of the relationship of age and liveweight (LW), five non-linear regression equations were tested for goodness of fit. Results: Colts and fillies had similar BW, weaning ages, weaning weights (WW) and average daily gain (ADG) between birth and weaning (ADG b-w). Weaning age explained 48% (p<0.001) of the variation in WW and 11% (p<0.001) of the variation in ADGb-w. After correction for weaning age, BW explained 16% (p<0.001) of the variation in WW and 6% (p<0.001) of the variation in ADG b-w. The best fit of age and LW was the polynomial equations based on Akaike's information criteria (AIC), residual variance (RV), residual standard deviation (RSD), and coefficient of determination (R2). The most accurate, biologically sound representation of growth was provided by Brody's type equation: LW = [b0- (b0-BW) x e(-b1 x age)], and an equation including BW: LW = [((b0 x BW x age) + BWb1)b2], that was developed in this study (b0 is an intercept, b1 and b2 are regression coefficients, and e is the base of natural logarithms). The advantage of the Brody's equation is that ADG at a given LW can simply be calculated as: ADG (kg/day) = (b0 x b1)-b1 x LW. Conclusions: The similarity of the present data with growth data from the Northern Hemisphere provides further recognition that foals reared on pasture can grow as well as foals reared in grain-based systems in the Northern Hemisphere. BW provides a logical set point for the explanation of growth of the foal up to weaning, rather than the use of polynomial equations, which do not fully describe the biology of growth, even though they provide an accurate mathematical description.
Publication Date: 2007-12-07 PubMed ID: 18059651DOI: 10.1080/00480169.2007.36788Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research study describes the mathematical modelling of the growth of Thoroughbred foals up to the point of weaning on different types of pasture in New Zealand. The findings suggest that birthweight is a primary determinant of growth, and also indicates that foals reared on pasture may grow as well as those in grain-based systems.
Study Methodology
- The study used data from 218 Thoroughbred foals (including 120 fillies and 98 colts) born over six years. These foals were raised on four different types of pastures.
- The researchers collected the foals’ liveweights twice a month, starting at birth up until the weaning stage, which is within 107 to 217 days from birth. A total of 3,200 data points were obtained.
- To ascertain the relationship between the age of foals and their liveweight, they performed a non-linearity test.
- They determined the goodness of fit of their data by testing five non-linear regression equations.
Study Results
- It was established that both foal genders had comparable birthweight, weaning ages, weaning weights, and average daily weight gain from birth to weaning.
- Weaning age accounted for nearly half of the variation in weaning weights and around an eleventh of the variation in daily weight gain from birth to weaning. After adjustments were made for weaning age, birthweight was found to explain 16% and 6% of the variation in weaning weight and daily weight gain, respectively.
- The best-fit equation demonstrating the relationship between age and liveweight was the polynomial equation, as determined by several criteria such as the Akaike’s information criteria, residual variance, residual standard deviation, and the coefficient of determination.
Conclusions
- The researchers concluded that the existing data align with growth information from the Northern Hemisphere, verifying that foals brought up on pasture can develop just as well as foals raised in grain-based systems.
- Additionally, the study reinforces that birthweight is a logical setpoint for predicting growth until weaning, as opposed to using polynomial equations that, despite giving an exact mathematical illustration, do not adequately depict the biology of growth.
Cite This Article
APA
Morel PC, Bokor A, Rogers CW, Firth EC.
(2007).
Growth curves from birth to weaning for Thoroughbred foals raised on pasture.
N Z Vet J, 55(6), 319-325.
https://doi.org/10.1080/00480169.2007.36788 Publication
Researcher Affiliations
- Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand. p.c.morel@massey.ac.nz
MeSH Terms
- Animal Feed
- Animal Nutritional Physiological Phenomena / physiology
- Animals
- Animals, Newborn / growth & development
- Birth Weight
- Body Weight / physiology
- Female
- Horses / growth & development
- Horses / physiology
- Male
- Mathematics
- Poaceae
- Weaning
- Weight Gain
Citations
This article has been cited 3 times.- Cappai MG, Taras A, Biggio GP, Dimauro C, Gatta D, Cossu I, Cherchi R, Pinna W. NEFA, BHBa, UREA and Liver Enzyme Variation in the Bloodstream of Weaned Foals up to 18 Months of Age. Animals (Basel) 2021 Jun 11;11(6).
- Takahashi Y, Takahashi T. Seasonal fluctuations in body weight during growth of Thoroughbred racehorses during their athletic career. BMC Vet Res 2017 Aug 18;13(1):257.
- Onoda T, Yamamoto R, Sawamura K, Inoue Y, Matsui A, Miyake T, Hirai N. Empirical Growth Curve Estimation Using Sigmoid Sub-functions that Adjust Seasonal Compensatory Growth for Male Body Weight of Thoroughbred Horses. J Equine Sci 2011;22(2):37-42.
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