Growth and conformation changes in the young Lusitano horse: evaluation from birth to one year of age

Abstract

Nowadays, there is a rising interest in the Lusitano breed as a sport horse. Besides the suggested relationship between growth rate and skeletal development, a better understanding of growing patterns could contribute for an accurate estimation of nutritional requirements in the growing horse. Therefore, the main objective of this study was to evaluate growth and development in Lusitano foals, from birth to one year of age, under extensive management conditions in Portugal. Thirty five foals from three stud farms were monthly weighed and withers height (WH), girth (G) and cannon circumference (CC) were measured. Average age at weaning was 7 mo (209±5d). Quadratic models were best fitted to describe the variation of body weight (BW), G, WH and CC. The effect of farm was significant for BW, G, and CC (P<0.0001), suggesting a management influence. Estimated BW at 7 and 12 mo of age in the three groups, varied between 211.1-253.8 kg and 274.6 327.7 kg, respectively, representing 42.2-50.8 % and 54.9-65.5 % of Lusitano mature BW (500kg). ADG until weaning varied between 0.786-0.888 kg/d, decreasing afterwards in the post-weaning period to 0.258-0.493 kg/d. Weight gain between birth and weaning represents 71.5-80.9 % of total weight gain until 12 mo of age. Estimated values for WH, G and CC at 12 mo of age varied between 135.4-140.9 cm, 145.4-157.5 cm and 16.7-19.0 cm, respectively. These results indicate a similar growth pattern to those described in other sport light breeds when submitted to moderate feeding levels, during the first year of life.vo