INFLUENCE OF DIFFERENT ZOO TECHNICAL INDEXES IN THE COMPOSITION AND EVOLUTION OF DAIRY CATTLE

Abstract

The aim of this work was to analyze the influence of different zoo technical indexes in the composition and evolution of dairy cattle through the years. Two hundred forty herds were simulated by combinations among the zoo technical indexes ages at the first birth (24,30 and 36 months), birthrate (100%, 90%, 80%, 70% and 60%), culling  (10%, 15%, 20% and 25%) and the female death rate from 0 to 1 year old, 1 to 2, 2 to 3 (3%, 6%, 9%, 12%, 2%, 4%, 6%, 8%, 1%, 2%, 3% and 4%, respectively). For the simulations of herd evolutions, the Computational System for Measurements and Evolution of Beef Cattle software was used. It was applied in the statistical analysis Kruskal-Wallis non-parametrical statistic, through NPAR1WAY procedure. Having observed significance in Kruskal-Wallis test, MULTTEST procedure was applied to verify the difference among the averages by the contrast. It was concluded the appropriate gaining of zoo technical indexes in the raise of dairy cattle influences the composition and evolution of herds, being the birthrate the most responsible for the herd evolution, followed by age at first birth, culling and death rates.

KEY WORDS: Dairy cattle, herd planning, reproductive efficiency, simulation.