Use of nonlinear models for describing scrotal circumference growth in Guzerat bulls raised under grazing conditions

Loaiza-Echeverri, A. M.; Bergmann, Jose Aurélio García; Toral, Fábio Luiz Buranelo; Osorio, Jair Pérez; Carmo, Adriana Santana do; Mendonça, Luiza Fernandes; Moustacas, Valéria Spyridion; Henry, M.

doi:10.1016/j.theriogenology.2012.11.031

Cited by 30 publications

(23 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…animals attained mature weight quickly) and low values indicate Lupi, León, Nogales, Barba and Delgado animals with a delayed maturity or that tend to mature more slowly. The parameter m gives the shape of the growth curve and, consequently, determines the inflection point, which is the beginning of the auto-deceleration stage until the animal reaches adult size (Carolino and Gama, 1993;McManus et al, 2003;Lambe et al, 2006;Echeverri et al, 2013;Tariq et al, 2013).…”

Section: Methodsmentioning

confidence: 99%

Genetic parameters of traits associated with the growth curve in Segureña sheep

Lupi

León²,

Nogales

et al. 2016

Animal

View full text Add to dashboard Cite

This paper studies the genetic importance of growth curve parameters and their relevance as selection criteria in breeding programmes of Segureño sheep. Logistic and Verhulst growth functions were chosen for their best fit to BW/age in this breed; the first showed the best general fit and the second the best individual fit. Live weights of 41 330 individuals from the historical archives of the National Association of Segureña Sheep Breeders were used in the analysis. The progeny of 1464 rams and 27 048 ewes were used to study the genetic and phenotypic parameters of growth curve parameters and derived traits. Reproductive management in the population consists in controlled natural mating inside every herd, with a minimum of 15% of the females fertilized by artificial insemination with fresh semen; with the purpose being the herd genetic connections, all herd genealogies are screened with DNA markers. Estimates of growth curve parameters from birth to 80 days were obtained for each individual and each function by the non-linear regression procedure using IBM SPSS statistics (version 21) with the Levenberg-Marquart estimation method. (Co)variance components and genetic parameters were estimated by using the REML/Animal model methodology. The heritability of mature weight was estimated as 0.41 ± 0.042 and 0.38 ± 0.021 with the logistic and Verhulst models, respectively, and the heritability of other parameters ranged from 0.41 to 0.62 and 0.37 to 0.61, with the models, respectively. A negative genetic correlation between mature weight and rate of maturing was found.

show abstract

Section: Methodsmentioning

confidence: 99%

Genetic parameters of traits associated with the growth curve in Segureña sheep

Lupi

León²,

Nogales

et al. 2016

Animal

View full text Add to dashboard Cite

show abstract

“…Parameter k represents the relative growth rate (rate of exponential growth); high values indicate animals with precocious maturity -that is, animals that attain maturity weight quickly, and low values indicate animals with a delayed maturity or that tend to mature more slowly. Parameter m gives the shape of the growth curve and, consequently, determines the inflection point, the beginning of the auto-deceleration stage until the animal reaches adult size (McManus et al, 2003;Echeverri et al 2013;Tariq et al, 2013). Quantitative growth can be characterized using the parameters of each model (Brown et al, 1976;Fitzhugh, 1976;Hamouda and Atti, 2011).…”

Section: Methodsmentioning

confidence: 99%

“…To select the best curve, there are five principal criteria of adjustment, mentioned by numerous authors (Gbangboche et al, 2011;Echeverri et al 2013;Tariq et al, 2013): determinative coefficient (pseudo R 2 ), mean square error (m.s.e. ), number of iterations, Akaike information criterion and biological coherence of the estimated parameters.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of commercial and biological growth curves in the Segureña sheep breed

Lupi

Nogales

León³

et al. 2015

Animal

View full text Add to dashboard Cite

Non-linear models were analysed to describe both the biological and commercial growth curves of the Segureña sheep, one of the most important Spanish breeds. We evaluated Brody, von Bertalanffy, Verhulst, logistic and Gompertz models, using historical data from the National Association of Segureña Sheep Breeders (ANCOS). These records were collected between 2000 and 2013, from a total of 129 610 weight observations ranging from birth to adulthood. The aim of this research was to establish the mathematical behaviour of body development throughout this breed's commercial life (birth to slaughter) and biological life (birth to adulthood); comparison between both slopes gives important information regarding the best time for slaughter, informs dietary advice according to animals' needs, permits economical predictions of productions and, by using the curve parameters as selection criteria, enables improvements in growth characteristics of the breed. Models were fitted according to the non-linear regression procedure of statistical package SPSS version19. Model parameters were estimated using the Levenberg-Marquardt algorithm. Candidate models were compared using the determinative coefficient, mean square error, number of iterations, Akaike information coefficient and biological coherence of the estimated parameters. The von Bertalanffy and logistic models were found to be best suited to the biological and commercial growth curves, respectively, for both sexes. The Brody equation was found to be unsuitable for studying the commercial growth curve. Differences between the parameters in both sexes indicate a strong impact of sexual dimorphism on growth. This can emphasize the value of the highest growth rate for females, indicating that they reach maturity earlier.Keywords: growth, models, sex, sheep, Zootechny ImplicationsNon-linear models can be an option to establish the mathematical behaviour of body development throughout the life of the Segureña sheep breed. These models require lower computational and faster convergence than other methods. Moreover, in genetic evaluation programmes with large data sets, non-linear models are more advantageous. The results showed a strong impact of sexual dimorphism on growth.

show abstract

“…La calidad seminal es determinada por volumen eyaculado, motilidad y morfología de las células espermáticas (Perry y Patterson, 2011). La circunferencia escrotal es frecuentemente determinada en programas de reproducción, por ser fácil de medir y de moderada a alta heredabilidad, además se ve asociado con características físicas del semen, edad a la pubertad, precocidad sexual y ganancia de peso (Loaiza-Echeverri et al, 2013). La explotación ganadera de la región se realiza de forma empírica, extensiva y poco tecnificada, de modo que estudios andrológicos de los reproductores son importantes para viabilizar económicamente la producción y realizar mejoras genéticas.…”

Section: Introductionunclassified

Avances de Investigación en Medicina Veterinaria y Producción Animal

González¹,

Rolón²,

Garza³

et al. 2016

View full text Add to dashboard Cite

Use of nonlinear models for describing scrotal circumference growth in Guzerat bulls raised under grazing conditions

Cited by 30 publications

References 38 publications

Genetic parameters of traits associated with the growth curve in Segureña sheep

Genetic parameters of traits associated with the growth curve in Segureña sheep

Characterization of commercial and biological growth curves in the Segureña sheep breed

Avances de Investigación en Medicina Veterinaria y Producción Animal

Contact Info

Product

Resources

About