This study was conducted at Fazenda Modelo an Experimental Estation belonged to the Instituto Agronômico do Paraná. (IAPAR), in the city of Ponta Grossa - PR, in the period from June2011 to March 2012. Purunã bovine females (n = 159) class were divided into three categories as follows: young cows (33-36 months old) adult cows (43-90 months old) and older cows (> 90 months). The negative energy balance was evident in all categories of cows with weight loss above 13 kg to 60 days postpartum. The pregnancy rate did not differ significantly among the three categories were 93% for young cows, old cows for 94% and 96% for adult cows. Adult cows weaned calves with higher weaning weight (221.20 kg) as compared to young cows (190.00 kilograms) and old (205.19 kg). Rates of the pregnant cow herd were not influenced by the category of beef cows when maintained in good body condition and nutritional at calving and during the breeding season. In these circumstances, young cows bred at two years of age are similar to productive and reproductive performance of mature cows, while the category of old cows has the lowest reproductive efficiency of breeding squad.