Effects of sugarcane fiber digestibility and concentrate level on performance of finishing Nellore bulls

Author(s)

Bruno de Souza Mesquita

• Document type: Master's Dissertation
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2013-07-05

Examining board members

Luis Felipe Prada e Silva; Maria Lucia Pereira Lima; Angélica Simone Cravo Pereira

• Advisor: Luis Felipe Prada e Silva

Abstract

Sugarcane has low fiber digestibility, one of the main factors limiting beef cattle performance. The objective of this study was to evaluate the effects of sugarcane stalk fiber digestibility and the concentrate level on intake, growth, carcass fat and economic performance of finishing Nellore bulls. Forty eight Nellore bulls (319 ± 9.2 kg of BW) were blocked by BW and assigned to 4 treatments in a 2x2 factorial arrangement in a randomized complete block design. Treatments were as follows: sugarcane genotype IAC2480 (greater stalk NDF digestibility) or sugarcane genotype SP1049 (lower stalk NDF digestibility), fed at 20 or 40% of total DM intake (n=4 pens for each of the four treatments). Diets were formulated to provide daily gain (ADG) of 1.2 kg/d (40% sugarcane) or 1.4 kg/d (20% sugarcane), and contained freshly cut sugarcane as the sole forage. Sugarcane IAC2480 stalk contained 39,4% NDF with 33,7% NDF digestibility, and sugarcane SP1049 stalk contained 42,1% NDF with 29,6% NDF digestibility. Animals were fed ad libitum maintaining a minimum of 10% orts in each pen. Dry matter intake was determined daily, and animals were weighed every 14 days after 16h of fasting. Main effects of sugarcane genotypes (Cane), of level of concentrate (Diet), and their interaction (Cane*Diet) were tested by ANOVA. Feeding sugarcane with higher NDF digestibility increased dry matter intake as a percentage of BW (2.24 vs. 2.12 ± 0.08%, P=0.002), final body weight (462 vs. 447 ± 20,8kg, P=0.04) and subcutaneous carcass fat of Logíssimus dorsi (4.57 vs. 3.12 ± 0.45 mm, P<0.01). There were no significant effects of level of concentrate or of Cane*Diet interaction on these variables. Deployment of interaction showed that effect of sugarcane occur only at the level of 80% of concentrate on average daily gain (1.73 vs. 1.45 ± 0.8kg/d, P<0.05), and at the level of 60% of concentrate on thickness of subcutaneous fat of Bíceps femoris muscle(7.82 vs. 4.96 ± 0.58mm, P<0.001), to the genotype IAC2480. There was no effect of sugarcane, diet and Cane*Diet interaction on feed:gain, and loy muscle area of Logíssimus dorsi. The use of IAC2480 sugarcane (greater digestibility) can increase hot carcass yield (P<0.06). The diet with the sugarcane IAC2480 promoted greater profitability, availed as revenue minus feeding cost. It concluded that fiber quality directly influence animal performance,because feeding finishing bull a diet containing sugarcane with greater fiber digestibility increased dry matter intake, improve the animal performance e increase subcutaneous carcass fat and the profitability of the system. (AU)

• FAPESP's process: 11/04800-6 - Evaluation of the importance of sugarcane fiber digestibility in diets for growing steers
• Grantee: Bruno de Souza Mesquita
• Support Opportunities: Scholarships in Brazil - Master