Puberdade e características da dinâmica folicular de novilhas F1 Holandês x Gir com fenótipos divergentes para consumo alimentar residual

This paper was carried out with the following objectives: a) to study and characterize the reproductive parameters until the first conception including the age and weight at puberty, estrus comportment, follicular dynamics, response to hormone protocols and fertility. The ovarian follicular dynamic was studied during the natural estrous cycle, after induction of estrum with prostaglandin F2, and after the protocol with progesterone and estrogen. The age and weight at puberty were 340,2 ± 27,6 days and 342 ± 25,0 kg respectively. The percentiles of estrum detection were of 94%, 84% and 100% for natural estrum, induced with prostaglandin F2, and after the protocol with progesterone and estrogen, respectively. The pattern of follicular waves during the estrum cycles prevailed in animals presenting three (60,6%), in relation to animals with two (39.4%), respectively. The interval of ovulations and the diameter of the ovulatory follicle were of 18,8 ± 1,0 and 21,8 ± 1,8 days and of 15, 7 ± 1,4 and 14,7 ± 1,1 millimeters for heifers F1HG with two and three waves, respectively. The gestation rate of the first artificial insemination was of 80% and there was no embryonic loss; b) to relate the nutritional efficiency with the age at puberty, weight at puberty and some reproductive parameters in F1 HG heifers. 35 heifers F1 HG were used, for each test, a food efficiency ranking was done, using as the parameter the residual feed intake (CAR). The heifers presented age at puberty averaging the 339,7; 346,4; 315.3 days, for heifers with high efficiency, intermediate efficiency and low efficiency, respectively, showing significant difference of puberty age between heifers (P<0,0001). The weight at puberty for heifers with high efficiency, intermediate efficiency and low efficiency was, in average, 321 ± 28.1kg, not showing difference between the CAR groups. No correlation was observed between the reproductive parameters of follicle diameter (mm), the follicle growth rate (mm/day), number of follicular waves in the natural estrous cycle and the gestation rate 1ª IA with the CAR groups.