Abstract
Objectives of this study were: (a) to compare live weight (LW) and zoometric measures (ZM) of local goats in two locations, (b) to fit the best regression equation for goat LW prediction using ZM. LW, body length (BL), trunk length (TL), withers height (WH), hearth girth (HG), rump width (RW), rump length (RL), head length (HL), head width (HW), and ear length (EL) were measured in 318 Local does in Amatepec and Tejupilco, State of Mexico. Statistical methods included student’s “t” tests for comparison of means, and correlation, principal components (PC), and multiple linear regression analyses. To evaluate the goodness of fit for LW prediction models the R2 value was used as a criterion. Differences (P ≤ 0.05) were found between does of Amatepec and Tejupilco in LW, BL, TL, HG, RL, HL, HW, and EL. In Amatepec, LW was correlated with HG, BL, and HW (P ≤ 0.01), whereas in Tejupilco LW was correlated with HG, BL, TL, and HW (P ≤ 0.01). From the Amatepec measures 5 PC were extracted, and which in a multiple regression analysis explained 83.3 % of the total variance, whereas from Tejupilco 4 PC were extracted, and which in a multiple regression analysis explained 82.4 % of the total variance. The best regression model to predict doe LW in Amatepec included TL, HG, RW, and HW, whereas for Tejupilco the best model included BL, HG, HW, and EL. It is concluded that: (1) Amatepec does surpass those of Tejupilco in LW and most ZM, (2) there are reliable ZM for predicting LW of local does in both locations, HG, and HW being common measures for both populations.
Highlights
It has been mentioned that breed characterization is a basic step to approach the sustainable use of animal genetic resource (Lanari et al 2003)
Live weight and zoometric measures The longer ears of Amatepec does, in addition to their superiority in live weight (LW) and other zoometric measures, suggest the possibility that they have a higher influence of the Nubian breed than Tejupilco does, a breed that has been classified as a dual-purpose goat breed (Merlos-Brito et al 2008)
Phenotypic correlations High correlations were found between hearth girth (HG) and body length (BL) with LW (P ≤ 0.01) in both populations (Table 3), which coincides with results obtained by Pariacote et al (2004)
Summary
It has been mentioned that breed characterization is a basic step to approach the sustainable use of animal genetic resource (Lanari et al 2003). In the State of México, México, the region with the largest goat production is located in the rural municipalities of Amatepec and Tejupilco, with about 59 % of the total state goat production (RebollarRebollar et al 2012), with a predominance of local goats (Montaldo et al 2010). The main product of goat farming in this region is meat; the trait of major interest for genetic improvement is live weight (LW). For goat producers in these locations it is very difficult to measure LW because most producers lack scales in order to weigh their animals, and sale prices depend entirely on live weight. Slippers et al (2000) consider that visual estimates are too subjective; Otoikhian et al.
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