Partição da energia e exigência de energia líquida para mantença de novilhas Gir e F1 Holandês x Gir

Abstract

The energy balance, energy requirements for maintenance and net efficiency of utilization of metabolizable energy for maintenance of Gir and F1 Holstein x Gir with average weight of 450 kg, were determined by using the respirometry technique. The DMI, OMI, NDFI and EI was higher for crossbred heifers, however, without cause differences in apparent digestibility. The loss of gross energy intake in the feces, urine and methane were 61%, 5.8% and 5.9%, respectively, without statistical difference between treatments. The percentage of GE lost as HI diet was similar for Gir and F1 HXG heifers being about 18% of ME accounted for 49% of GE intake and its conversion to NE (k) had 63% efficiency. The energy density (EB, ED, EL and EM, expressed in Mcal/kg) of the diet was similar between the genetic groups, and the content of NE of the same averaged 1.39 Mcal/kg. The net energy for maintenance was statistically similar between groups, with an average of 84.43 kcal / kg LW0, 75.