Celularidade hepática e composição da carcaça de novilhas zebuínas gestantes e não gestantes.

Abstract

This study aimed to evaluate the effect of pregnancy on carcass composition and changes in the concentration of biomolecules in the liver. Eighty Zebu heifers were used, with up to two permanent incisor teeth, from three commercial farms, which were raised on Urochloa brizantha (cv. Marandu) and Mombasa pasture and supplemented with mineral mixture. To confirm the pregnancy, the uterus was evaluated and 20 non-pregnant and 60 pregnant heifers were selected, which were classified into three groups according to the size of the fetus (cm) to characterize the fetal age. The experiment was carried out in an incomplete block design, with four treatments and twenty replications, as follows: NG - non-pregnant heifers; G1 - pregnant heifers in the first trimester G2- pregnant heifers in the second trimester, and G3-pregnant heifers in the third trimester. in the third trimester The section was then dissected into muscle, fat and bone. In addition, it was analyzed for water, mineral matter, crude protein and ether extract. Liver samples were collected immediately after evisceration for DNA, RNA, and total protein analysis There was a decreasing linear effect of the carcass ether extract content (P=0.007) and adipose tissue percentage (P=0.010) as the fetal size increased (gestational stage). The proportion of crude protein in the carcass of non-pregnant heifers was lower than that of pregnant heifers in the third trimester (P<0.001), with no effect being verified when analyzing the proportion of muscle among pregnant heifers (P=0.113). The concentration of DNA in the liver linearly increased as a function of the size of the fetus (gestational stage; P=0.002), however, no effects were observed on liver RNA (P=0.209) and total protein (P=0.411) concentrations. Therefore, it is concluded that the lower proportion of ether extract due to the increase in fetal size (gestational stages) associated with a lower proportion of adipose tissue for pregnant heifers in the third trimester indicate that the heifers mobilized reserve tissues to meet the requirements maternal energetics. In addition, there is evidence that the liver had to resort to cell proliferation to meet the high metabolic rate required by the dam through the higher concentration of DNA in liver cells.