Body composition and net energy and protein requirements of Santa Gertrudis bulls fed high concentrate diets

Author(s)

Alexandre Berndt

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2001-01-25
• Advisor: Dante Pazzanese Duarte Lanna

Abstract

The effect of com grain harvested at 87%DM or harvested at 70%DM ground and ensiled were evaluated. Diets contained different roughage sources, either com silage (20% of the diet DM) or sugarcane bagasse (12% of the DM). Thirty two Santa Gertrudis bulls with initial average age of ten months and initial average weight of 245kg were fed an adaptation diet for 33 days after which four animal were slaughtered to obtain initial body composition. The other 28 animals were distributed to the four treatments for a 124 days experimental feeding period. The experimental design was randomized blocks in 2 X 2 factorial arrangement (two roughage sources X two com grain sources) with seven repetitions, testing the following treatments: com silage+high moisture com (Si-MU); com silage+dry com grain (Si-MS); sugarcane bagasse+high moisture com (Ba-MU) and sugarcane bagasse+dry com grain (Ba-MS). There were no interactions between roughage source and grain sources for any variable evaluated. Com silage was superior to sugarcane bagasse for daily empty body gain,and for rates of deposition of all chemical components and energy. High moisture com increased fat and energy content in the weight gain as well as the rate of lipid deposition. Data demonstrated that sugarcane bagasse is a poor roughage source in high concentrate diets when compared to whole plant com silage. Results are also consistent with an increase in net energy content of ensiled com grain. Net requirements of energy for maintenance were determinated by the regression equation of the log ofheat production as a function of metabolizable energy intake at zero feed intake obtaining a value of 82,2 Kcal/kg EBW 0,75.d. Regression equation of the log of body energy content as a function of log of empty body weight (EBW) provided estimation of body energy and protein content at any EBW range included in this research: for weight gain of 1 kg, an animal of 300 kg require 3,64 Mcal/day of energy and 129,5g of protein (AU)