Interval between births and their relationship to adult size in Criollo and Aberdeen Angus colorado cattle

Abstract

Best efficience in cow meat range systems is related with a smaller partum interval time. The aim of this work is to compare differencies in partum interval and frame between Criollo and aberdeen angus cows. Data provided include 52 Criollo cows and 107 Aberdeen Angus cows under the same environmental conditions. Information analysis includes quntitative variables by one hand, such as IPI (first partum interval), IP2 (second), IP (where both intervals are not discrimined) and Alz (frame), and by the other qualitative variables, that is, R1 (Aberdeen Angus breed), R2 (Criollo Breed), and the upper quantitative variables but classified in an ordinal form. Linear regression analisys is imprved because of year effect. Basic statistics are measured, and regression and variance analysis, and CM (multiple corresponse determination) are also improved. About proportionality, chi square is used. There are signifficative differencies between breeds. Criollo breed appears related with the smaller IP2 and the higher frame.