The growth curves for some biometric traits in Czech Warmblood stallions

Abstract

• Growth patterns of the Czech Warmblood stallions were studied. • Brody model was used to describe the growth of four biometric traits. • Percentile and Z-score growth curves were established. The possibility of growth tracking gives breeders the opportunity to analyse animal development and monitor it in daily farm management. Therefore, it is important to establish an ideal growth rate for each breed. The main objective of the present study was to characterise the growth patterns of Czech Warmblood (CW) stallions and establish their growth curves. A total of 7,488 records for withers height (WH) measured by stick (WH s ), WH measured by tape (WH t ), girth (G) and cannon circumference (CC) were obtained from 117 warmblood stallions raised at five rearing facilities for testing young horses (RFT). Data were regularly collected from 7 to 36 months of age. Brody's equation was adjusted using the non-linear (NLIN) procedures of Statistica software, version 12 (TIBCO®). Growth rates (adjusted daily gain [ADG], cm/d) were obtained from the first derivative of the equations. The mean mature sizes were 167.4 ± 0.7 cm, 177.1 ± 0.8 cm, 194.3 ± 0.9 cm and 21.8 ± 0.1 cm, respectively, for WH s , WH t , G and CC. The slowest growth rate was observed at WH (0.0026 ± 0.0001) and the fastest at CC (0.0032 ± 0.0002). The highest degree of maturity at birth was predicted at WH (70%) and the lowest at G (51%). The WH s degree of maturity at 6, 12, 18, 24, 30 and 36 months of age were 83, 88, 92, 94, 96 and 97%, respectively. The G degrees of maturity for the same ages were 76, 84, 90, 94, 96 and 98%. Ages at 99% of mature WH s , WH t , G and CC were 42, 44, 46 and 38 months, respectively. It follows that CC approached the asymptotic value as the first one and G as the last one from the monitored biometric traits. Percentile and Z -score curves were established for all evaluated biometric traits. Percentiles with intervals from the 25th to 75th as the standard of CW stallions appeared more appropriate for breeders, as they tend to be intuitive and more easily understood. The present study provided detailed information about the growth of CW stallions, which revealed useful indicators for breeding management.