Relação da idade e do peso de novilhas Girolando com o desenvolvimento uterino e ovariano

Abstract

Due to the predominance of Girolando breed in Brazilian dairy cattle and aiming to gain more knowledge about the reproductive development of this breed, the present study aimed to relate the age and weight of Girolando heifers with uterine and ovarian development up to first ovulation. To this end, 60 heifers from the dairy cattle facility belongs to Federal Rural University of Rio de Janeiro were selected, free from any type of condition in the congenital or acquired reproductive tract. From 12 months of age up to first ovulation, these animals were weighed monthly in electronic scales and, at the same time, they were evaluated with the aid of the ultrasound device where the diameters of each uterine horn and ovaries were measured. The animals were divided into groups according to their age in each month, distributed in GI (12 to 14 months), GII (15 to 18 months), GIII (19 to 24 months), GIV (25 to 30 months) and GV (31 to 36 months). The scatter plot was used to assess the relation between monthly data collected from uterus/ovary and weight/age. A mean daily growth of 0.0032mm for the right ovary (OD) and 0.0051mm for the left ovary (OE) was observed, as well as mean OD size 17.58mm and OE 15.28mm OD, OD 16.72mm and OE 15.89mm in GII, OD 18.37mm and OE 16.55mm in GIII, OD 19.09mm and OE 17.49mm in GIV and OD 19.89 mm and OE 18.96mm in the GV. The uterine horns had an average daily growth of 0.0064mm and 0.0071mm for the right (UD) and left (UD) horns, respectively. Mean size per group of UD 11.46mm and EU 11.48mm, UD 12.41mm and EU 12.63mm, UD 13.16mm and EU 13.19 mm, UD 14.30mm and EU 14.58mm and UD 16.12 and EU 16.68mm, for the GI, GII, GIII, GIV and GV groups, respectively. The heifers presented a mean daily weight gain of 0.224kg and the GI, GII, GIII, GIV and GV groups had a mean weight of 220.5kg, 239.3kg, 287.6kg, 332.9kg and 380.1kg, respectively. Heifers had a mean age of 29.67 months, with a weight of 354.2kg, age at first service of 33.5 months, pregnancy rate of 64.7% and first birth on average at 42.8 months. We conclude that the ponderal development is related with the growth of the ovary and uterine horns, and that they relate positively with each other with the advance of the age of the animal