Avaliação do crescimento de potros da raça Crioula utilizando modelos não lineares

Abstract

The present study was developed with the objective of evaluating the growth of Crioulo foals from birth to two years of age, using nonlinear models of Brody, Gompertz, Logistic and Von Bertanlanffy. Data on weight, height, thorax and shin circumference measured in 75 foals from two properties located in southern Brazil were used. Weight was measured individually, using a conventional scale. The height was obtained using a hypometer, with the foals positioned with the four limbs resting on the ground, on a horizontal and uniform floor. The thorax perimeter was measured using a measuring tape, passing to the end of the withers. The shin perimeter was obtained with the aid of a curved measuring tape at the level of the medial third of the third metacarpal of the left forelimb. The morphometric measurements studied showed values ranging from 63kg to 325kg (weight), 0.92m to 1.32m (height), 0.88m to 1.58m (chest perimeter) and 0.12m to 0.18m (shin perimeter). For weight, height and chest circumference characteristics, the Brody model presented the best adjustments. The Gompertz model was the most suitable to describe the growth curve of the shin perimeter. Part of the population did not meet the minimum measures required by the race for the characteristics of height and thoracic perimeter. The most accelerated increase in the height of the animals was observed until approximately 12 months of age, decreasing and presenting homogeneity later on. Chest circumference showed more homogeneous growth in animals from 12 months of age up, with slower growth and greater variability observed from 18 months of age. The shin perimeter showed a significant growth in the first months of life, showing stability up to 24 months.