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

Abstract

The objective of this study was to evaluate the relationship between longevity with productive and reproductive efficiency variables of Nelore cows in grazing systems in the Bolivian tropics. Retrospective data corresponding to the period 1992-2019, belonging to the Cooperativa Agropecuaria Integral San Juan de Yapacan and the Foundation Technology Center on Agriculture and Livestock, Santa Cruz-Bolivia were used. The data corresponding to 774 Nelore breed cows, primiparous and multiparous discarded with a total of 4050 calvings were evaluated. The following variables were analyzed: Number of calves, live weight of cow in kg, calf weight at birth in kg, calf weight at weaning in kg, total calf weight in kg, age at first calving in months, longevity in days and calving interval in days. Cows born in the year (1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995) are those that arrive later to have their first calving, have a greater calving interval, have greater longevity, similar weaning weight, lower birth weight, lower live weight and higher weight total calf. While cows born in the year (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) are those that arrive younger to have their first calving, they have a shorter calving interval; have shorter longevity, similar weaning weight, higher birth weight, live weight intermediate and lower total calf weight. For the three periods analyzed, the length of life increases between 0.66-0.95 days on average when the age at first calving increases by one unit, between 1.78-2.99 days on average when the calving-calving interval increases by one unit and between 1.77-1.83 days on average when total calf weight increases by one unit. It is concluded that it was possible to find a model that explained that the greater longevity of Nelore cows in a grazing system in the Bolivian tropics was related to the older age at first calving, the greater calving interval and the greater kg of weights total calves.