Evaluation of Morphometric Measurements of Dorper Lambs of Different Age Groups

Abstract

Morphometric measurements are easy tools to adopt for characterization of breeds, as well to select the best animals for breeding. Therefore, the objective of this study was to characterize the morphology of Dorper lambs of different age groups. The study was conducted at Sheep Unit of the Instituto de Zootecnia, located in Nova Odessa, SP. A total of 26 registered uncastrated male lambs from nine sheep farms in three different states (São Paulo, 7; Santa Catarina, 1; Paraná, 1) were used. The average age was 102.30 ± 16.30 days and average body weight was 26.10 ± 4.14 kg. Initially, the animals were weighed (kg) and then 13 morphometric traits were measured: withers height (WH), rump height (RH), withers depth (WD), rump depth (RD), chest width (CW), withers width (WW), rump width (RW), body length (BL), chest girth (CG), rump girth (RG), shoulder girth (SG), leg girth (LG) and scrotal circumference (SC). The lambs were separated into three age groups, divided according to ± 0.5* age standard deviation: AG1 (67 to 93 days, n = 9), AG2 (99 to 105 days, n = 8) and AG3 (112 to 135 days, n = 9). The effect of age group was used to compare the morphometric measurements by the Tukey test at 5% significance (SAS). No significant differences were identified according to the age groups. However, some measures of the AG3 group had lower values (CW = 23.42 ± 1.70; WW = 23.65 ± 1.60; RW = 25.82 ± 1.79; BL = 59.45 ± 2.97; CG = 69.33 ± 4.5; RG = 69.45 ± 4.47; and SG = 23.73 ± 1.34; LG = 36.47 ± 3.58), although the lambs were older. Therefore, the morphometric characterization of Dorper lambs did not differ using a 72-day interval.

Keywords

• Body weight
• morphology
• productive efficiency
• sheep