Estimation of growth parameters in Brahman cattle from Mexico

Abstract

The objectives were to evaluate non-linear models (NLM) to define the growth curve of Brahman cattle in Mexico. The database was derived from weight development control, with live weight measurements (150,932 in females and 286,804 in males) taken in the interval from birth to 1095 days of age. Four NLM were evaluated: Brody, Bertalanffy, Gompertz and Logistic. The selection of the NLM with the best adjustment was made based on the Akaike and Bayesian information criteria. Growth parameters were generated: adult weight (AW), growth rate (GR), correlation (ϒ) between AW and GR, age and weight at the inflection point, evolution of live weight (as a percentage of adult weight), maturity level, daily growth rate (DGR; kg/day). The model with the best fit was Brody, followed by Bertalanffy. For AW, the average value was 787.2 kg for males and 592.1 kg for females; for GR, the average values (%) were 0.28 for males and 0.25 for females. All ϒ were less than -0.90. The DGR, for males presented values in the range of 0.347 to 0.786 and a mean of 0.537; for females, the mean was 0.424 with values in the range of 0.274 to 0.620. Heifers at 15 months of age reach an average weight of 287 kg, representing 57.7% of the adult weight. The growth analysis shows the response and/or adaptation to tropical livestock, based on a growth curve with a constant growth rate and no inflection point