Dry matter intake fluctuations, rumen morphometrics and liver abscesses in feedlot Nellore cattle fed only virginamycin to shorten the adaptation period

• Grant number: 17/23660-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date until: March 01, 2018
• End date until: November 30, 2018
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Eduardo Lima Caixeta
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

The objective of this study will be to evaluate whether feedlot Nellore cattle can be adapted in less than 14 days to the high concentrate diet when only virginiamycin (VM) is used as a feed additive. To achieve this goal, variables of fluctuation of dry matter intake, rumen papillary morphometry, incidence of rumenitis and hepatic abscesses will be evaluated. It will be used 120 Nellore bulls with initial average weight of 370 kg from backgrounding in a continuous grazing system. The animals will be randomized into 30 pens according to the treatments: 1) Monensin (MON; 30 mg / kg) with adaptation for 14 days; 2) MON (30 mg / kg) + VM (25 mg / kg) with adaptation for 14 days; 3) VM (25 mg / kg) with adaptation for 14 days; 4) VM (25 mg / kg) with adaptation for 9 days; and 5) VM (25 mg / kg) with adaptation for 6 days; thus constituting a complete randomized block design. Each treatment will consist of six pens, which will be considered the experimental units in this study. After 6, 9 or 14 days of adaptation, the animals will receive the final diet containing 84% concentrate, which will contain: 14.0% of sugarcane bagasse, 2% of chopped hay, 70% cracked corn grain, 10.7% soybean meal, 2.4% mineral supplement and 0.9% urea. For fluctuation of dry matter intake, the average intake information of the animals from each pen will be collected daily from weighing the amount of feed offered and the leftovers a day later. After slaughter, the rumen of all animals will be evaluated for incidence of rumenitis. Subsequently, fragments of 1 cm2 of the cranial sac of the rumen of each animal will be collected for ruminal morphometric analyzes. In the same way, the incidence of liver abscesses will be assessed after slaughter. (AU)