Abstract

DOMINGUEZ-VIVEROS, Joel et al. Characterization of growth of Cebu cattle in testing performance on grazing. Ecosistemas y recur. agropecuarios [online]. 2017, vol.4, n.11, pp.341-348. ISSN 2007-901X.  https://doi.org/10.19136/era.a4n11.1149.

The objective was to characterize the growth of Cebu cattle in grazing performance tests. We used 15 990 live weight data, taken between 150 and 630 d of age, of 3 198 males with five weights each: 1) weaning weight (WW), 2) initial test weight (IW), 3) first weighing (W1), 4) second weighing (W2) and 5) final test weight (FW). Nonlinear models (NLM) were compared: Brody (BRO), Logistic (LOG), von Bertalanffy (BER) and Gompertz (GOM). Two types of analyses (ANA1, ANA2) were carried out with the SAS NLMIXED procedure: ANA1 with mixed NLM (MNLM), by including the random effect of a regression coefficient; and ANA2 with MNL, with no random effects associated with regression coefficients. The model was selected using the criteria of mean prediction error; variance of the prediction error; Durbin Watson statistic; coefficient of determination; Akaike information criterion and Bayesian criterion. The mean weights (kg) for WW, IW, W1, W2 and FW were 175.9 ± 33.4, 182.5 ± 32.1, 225.8 ± 49.6, 266.8 ± 61.9 and 340.3 ± 68.1, respectively. Analyses with MNLM (ANA1) presented better results, with LOG being the best fit, followed by GOM, BER and BRO. The ANA2 results were overestimated and out of context to be associated with bovine growth; the growth curves generated with MNLM showed good predictive capacity and were based on the data generating process, which refers to the growth of Cebu cattle.

Keywords : mixed nonlinear models; tropical livestock; growth curves; adult weight; growth rate.