Evaluation of the importance of sugarcane fiber digestibility in diets for growing steers

• Grant number: 11/04800-6
• Support type: Scholarships in Brazil - Master
• Effective date (Start): August 01, 2011
• Effective date (End): August 31, 2012
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal researcher: Luis Felipe Prada e Silva
• Grantee: Bruno de Souza Mesquita
• Home Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Forages form the basis of ruminant nutrition, and cell wall digestibility is the main factor limiting animal performance. The identification of a parameter for fiber quality evaluation that effectively has an impact on animal performance is of great importance for sugarcane breeding programs. Our objective is to evaluate the effect of offering diets, containing sugarcane made from genotypes with either high or low stem NDF digestibility, for growing steers over the following parameters: 1) dry matter intake; 2) body weight gain and variation in body condition score; 3) ruminal digestion and passage rate of NDF; 4) ruminal parameters; and 5) quantification of amylolytic and cellulolytic bacteria. Fifty eight Nelore steers of approximately 350 kg will be used, with eight steers being cannulated in the rumen. Experimental diets will be composed of 50 or 70% concentrate in the dry matter and sugarcane silage from two genotypes, with either high or low stem NDF digestibility, will be used as roughage, in a total of four experimental diets. Intake will be individually measured. The experimental design will be that of random blocks with 12 repetitions (performance) and duplicated 4X4 Latin square (rumen metabolism and kinetics). The total rumen content mass and volume will be determined in the cannulated steers. Samples will be taken from both solid and liquid phases for determining the size of the rumen pool for diet components. Diet, orts and ruminal digesta will be analyzed for nutrient contents. The NDF ruminal passage rate (kp), digestion rate (kp) and finally apparent ruminal digestibility will be calculated. Polietilenoglicol with molecular weight of 4,000 will be used for determination of liquid volume and liquid passage rate at the rumen. (AU)