STRUCTURAL INDICES IN LOCAL GOATS UNDER EXTENSIVE GRAZING SYSTEMS IN THREE GEOGRAPHIC REGIONS OF MEXICO

Abstract

The objective of the study was to evaluate morphometric variables (MV) and structural indices (SI) in local goat populations from three geographic regions of Mexico: Coahuila, Zacatecas, and Guerrero. Al total of 194 adult, non-pregnant goats, owned by smallholder farmers and managed under extensive conditions were utilized in the study without prior sampling selection. The sample included 71 goats from Coahuila, 50 from Zacatecas, and 73 from Guerrero. Live weight (LW) and 12 MV were recorded for each animal and used to calculate 14 SI: body index, compactness index, cephalic index, cranial index, pelvic index, dactyl-thoracic index, dactyl-costal index, relative shortness index, length index, longitudinal pelvic index, transverse pelvic index, relative cannon thickness index, and body capacity indices 1 and 2. Statistical analyses included analysis of variance (ANOVA) to assess differences among regions and correlation analysis to evaluate relationships between MV and SI. Significant differences (P£0.05) in LW and 10 of the 12 morphological variables were observed among regions. Higher values for LW, chest width, head width, and cannon bone perimeter were recorded in goats from Coahuila and Zacatecas. Skull and rump lengths were greater (P£0.05) in goats from Zacatecas and Guerrero,  whereas head length and skull width were higher (P£0.05) in Guerrero. In contrast, body length and withers height were greater in goats from Coahuila (P£0.05). Phenotypic correlations among MV indicated a high degree of body harmony within these populations. Ethnological SI indicated that goats across the three regions are classified as brevilinear, dolichocephalous, and convexilinear. SI related to productive aptitude indicated that goats from Guerrero are primarily dairy animals, while those from Coahuila and Zacatecas are dual-purpose animals (meat and milk production).