FACTORS AFFECTING HASTEN OF REPRODUCTIVE AGE IN TAURINE AND ZEBUINE HEIFERS

It is well established that the timing of the first pregnancy in heifers has a major influence on their lifetime reproductive performance. However, zebuine heifers typically show delayed puberty with the first calving often occurring at around 36–48 months of age. Several factors affect the reproductive efficiency in heifers, such as weight, age, body condition, uterine development and genetics. The thickness of subcutaneous fat efficiently predicts the risk for the establishment of puberty and pregnancy in 14-month-old Nelore heifers submitted to FTAI. It was found that heifers with greater subcutaneous fat thickness were more likely to achieve puberty and to become pregnant at FTAI. Through adequate nutritional management combined with genetic selection for sexual precocity, it is possible to obtain also satisfactory reproductive efficiency in precocious primiparous. When the basic requirements (mainly nutrition and genetics) are met, the anticipation of the conception of heifers can be successfully established, improving the productivity and profitability of breeding livestock.