Levels of dry matter intake on metabolites and hormones plasmatic and follicular hormones in beef heifers

Abstract

This study was carried out to evaluate the effect of dry matter intake (DMI) on metabolites and plasmatic and follicular hormones. Twenty seven crossbreed ½ Nelore x ½ Angus heifers were allocated in the 3 groups, with 9 replications each: 1.2%, 1.6% and 2.6% of DMI/day on the relation of body weight. One hundred forty two days after the beginning of experiment the oestrous cycle was synchronized. Five heifers from each group were catheterizated in the caudal vena cava. Blood was collected via jugular vein and caudal vena cava every two days up to 12th day of the oestrous cycle from 8th FSH application, 11 blood samples were collected from jugular vein every 4 hours to determine glucose, insulin, urea, estradiol-17B and progesterone in plasma. Four heifers from each group were ovarioctemized in the 7th FSH doses and IGF-I, estradiol-17B and progesterone levels were determined in fluid of the mean and large follicle. Glucose levels (83.02 mg/100 mL) and estradiol-17B(1796.93 pg/mL) were superior (P<0.05) in the jugular vein from heifers with 1.6% of DMI. However, levels of insulin (13.96 mU/L) were higher (P<0.05) for heifers receiving 2.6% of DMI. Levels of urea were higher (P<0.05) as DMI increased. Levels of progesterone, in plasma of jugular vein, were not affected by DMI. However, levels of progesterone were higher (P<0.05) for heifers receiving 2.6% of DM (11.77 ng/ml) than for heifers receiving 1.2% of DM (6.39% ng/ml). It can be concluded that not always the plasmatic hormonal variation is reflected in to follicular level.