CRESCIMENTO E DESENVOLVIMENTO DO CAVALO PURO-SANGUE LUSITANO: A LEPTINA COMO POSSÍVEL MODULADOR DO META- BOLISMO ÓSSEO

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Growth and development of the Lusitano foal on extensive systems

Publication . Fradinho, Maria João de Sousa Ferreira Martelo; Dias, Graça Maria Leitão Ferreira; Caldeira, Rui Manuel de Vasconcelos e Horta

The general aim of this study was to characterize the growth and development of the Lusitano foal bred and raised on extensive systems. In particular, the relationship between growth patterns and bone quality was evaluated. Additionally, nutritional status and body condition (BC) changes of the mares during the productive cycle were studied, in order to stablish appropriate scores to optimize the development of foals from pregnancy to weaning, as well as to increase the productive efficiency of the system. A longitudinal field study was conducted in four Lusitano stud-farms. Broodmares were monitored during three consecutive gestation/lactation cycles and foals were followed from birth to 42 months of age. The biomechanical properties of equine cortical bone were also assessed. Results showed that changes in broodmare body weight (BW) and BC were mainly influenced by pasture availability and quality and when the foaling season occurs in the year. The reproductive performance of mares and the growth of suckling foals were also clearly influenced by broodmare nutritional status. BC score changes at mating had a strong effect on fertility outcome of the first two estrous cycles after foaling, being highly impaired by BCS negative changes, whatever the BCS. Best fertility results were obtained with positive and greater BC changes. The Richards function was used to characterize foals’ growth patterns and growth curves were obtained for BW, withers height (WH), girth and cannon circumference. Lusitano foals showed slower BW growth rates, comparable with moderate growth levels proposed for other sport breeds. In contrast, WH growth rates were similar to those presented by early maturing breeds. The validity of the quantitative ultrasonoghraphy as a non-invasive method for the in vivo assessment of bone mechanical properties and overall bone quality was also demonstrated. Changes in foals BW and WH growth rates were associated with the presence of radiographic findings compatible with osteochondrosis (OC) lesions at the onset of training. When compared to healthy foals, OC positive foals seem to be early maturing as regards to BW, and showed a tendency for worse cortical bone quality, lower IGF-I and higher insulin and PTH concentrations. The results underline the importance of an early monitoring of foals’ growth during the first year of life in order to avoid sudden changes to the average growth rates and to promote a better osteoarticular quality of the Lusitano horse. The integrated approach in what concerns mares and foals management decisions, in particular the choice of the foaling season and the introduction of adequate feeding strategies, will be determinant for the improvement of the efficiency and profitability of the Lusitano production systems.

2016-03-23Tese de doutoramento

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Fundação para a Ciência e a Tecnologia

Número da atribuição

SFRH/BD/29890/2006