The effect of sex and livestock production system (LPS) on growth performance and carcass characteristics of Mirandesa breed calves was studied. A total of 2,263 and 60 animals for growth performance and carcass characteristics, respectively were used. Initially, the suitability of several equations to describe the growth of cattle from the Mirandesa variety was studied. In all situations, mathematical models were formulated with parameters of clear biological meaning. Bertalanffy and Gompertz equations were the most satisfactory equations to model the growth of males and females, respectively. Calves from traditional system were 68.61 kg heavier than animals from extensive system. On the other hand, calves from traditional systems showed (P<0.01) higher dressing percentage compared to animals from extensive system. There were significant differences for all morphometric parameters by LPS effect with the exception of internal depth pf chest, whereas sex effect had less importance. The LPS had statistically significant effect in all individual joints in the front quarter and hind quarter with the exception of sirloin and eye of round for front quarter and shoulder and the sum of chuck plus neck in the hind quarter. Finally, the LPS had statistically significant effect in all components of fifth quarter, with the exception of intestines, liver, tail and spleen, whereas sex effect only affected heart proportion.
Sousa F, Lorenzo J.M, Vazquez J.A, Cantalapiedra J, Iglesias A, Franco D.