Effects of breed type and age at first calving on length of productive life in a cow–calf system in Southeastern Mexico

Abstract

The effect of age at first calving (AFC) and breed type (BG) on cow length of productive life in the herd (LPL) and cumulative kilograms of calves weaned per cow (KWC) was studied. Data on 313 Brahman, 183 Nellore, and 269 crossbred cows (undefined crosses of European × Zebu cattle) born from 1986 to 2002 were used. Three hundred and ninety-one out of the 765 cows had non-censored data. LPL curves by BG and AFC (<2.5, 2.5 to <3, 3 to <3.5, and ≥ 3.5 years of age) were obtained using life table procedures. The magnitude of the effect of AFC and BG on LPL was determined using Cox proportional hazard regression procedures. KWC data (n=359) were analyzed by a linear model that included the effects of period of birth of the cow (in years), BG, and AFC. There was no difference in the survival curves between BG (p>0.05), but there was for the hazard ratio of culling (p<0.05). Brahman and Nellore cows produced more kilograms of calves (p<0.05) than crossbred cows. AFC influenced LPL (p=0.014) and KWC (p=0.012). Cows with AFC <3 years of age stayed longer in the herd and weaned more KWC than those with a higher AFC (p<0.05).

Relationship of Longevity with Productive and Reproductive Variables in Nelore Cows of the Bolivian Tropic

“…The results for the decades 1995-2005 and 2005-2015 are below the 38.7 months found by (García et al, 2003) and are similar to the 35.6 months presented by (Flores and Ortiz, 2010) both in Nelore cattle. The age at first calving can influence the number of calvings of a cow during its useful life in the herd, because the greater sexual precocity of the cows would lead to a longer productive life (Nunez-Dominguez et al, 1991, Vukasinovic et al, 2001Rogers et al, 2004;Aranda-Avila et al, 2010). In this study, the results do not coincide with the aforementioned authors, since in the model estimates for the three periods studied, an increase in the age at first calving by one unit increases the longevity of the cows.…”

Análisis Socioeconómico Para Identificar Oportunidades De Desarrollo De La Ganadería Doble Propósito en Tropico Seco

“…El 60.0% del inventario corresponden a bovinos de DP de razas Bos indicus principalmente Brahman, Nelore, Guzerat y Gyr (SIAP-SAGARPA, 2014). También, se observan cruzas entre estas razas con Bos taurus como Holstein y Pardo Suizo para la producción de leche y con razas como Charolais y Simmental, para producir carne (Aranda-Ávila et al, 2010;Pech et al, 2002). Asimismo, la actividad se caracteriza por el aprovechamiento estratégico de los recursos disponibles en las UP como pastizales, pastos, arbustos y árboles para alimentación del ganado (Absalón-Medina et al, 2012 b) y utilización de mano de obra familiar para la realización de las actividades agrícolas y el manejo del ganado (García-Martínez et al, 2015).…”