Characterization of ruminal acidosis during the transition period in beef cattle

• Grant number: 15/11702-1
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: July 21, 2015
• End date: November 20, 2015
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Daniel Hideki Mariano Watanabe
• Supervisor: Gregory Penner
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Dracena. Dracena , SP, Brazil
• Institution abroad: University of Saskatchewan (USASK), Canada
• Associated to the scholarship: 13/21666-7 - Performance, feeding behavior, carcass traits, rumen health, and starch digestibilty of Nellore and 12 Angus/Nellore cattle adapted in feedlot for 9 or 14 days, BP.MS

Abstract

The aim of this study is to determine the incidence, prevalence and severity of ruminal acidosis in feedlot cattle during the transition phase, as well as to determine the relationship between acidosis early in the feeding period and animal health status for the entire feeding period. A subset of 32 steers (with background information collected in the beginning of the study) from 800 steers (BW = 400 kg) receiving a step-up feedlot diet will be used in this experiment. Steers will be orally dosed with indwelling ruminal pH measurement system and will be allocated in to 8 pens. Animals will be fed three times daily and the TMR and the feed ingredients will be sampled and DM, NDF, starch, ether extract and ash will be determined. Measurements of BW of animals used in the trial will be taken at the initiation, each time through the chute (for treatment), at re-implant, and terminal sort. BW will also be measured on the day of shipping. Ruminal pH will be measured 15 min until the logger memory is filled (4 weeks). Ruminal pH data will be then summarized for each steer on a daily basis and minimum, mean, and maximum pH values will be determined and the time that ruminal pH < 5.5 (DUR) and the area that ruminal pH < 5.5 (AREA) will be calculated. Feeding behavior of animals will be monitored during this study. Animal health data will be collected at the end of the feeding period in the form of pull rates, treatment records and post-mortem records as provided by the feedlot and their veterinarians. Once market weight is reached, the 32 steers will be shipped for slaughter at a federally inspected facility, with cohorts being slaughtered at a second large scale slaughter facility. The digestive system of each of the 32 animals will be collected and the ruminal pH meter system will be retrieved. Ruminal pH data will be then downloaded and analyzed as discussed. The rumens will be washed and lesions of the ventral and caudo-ventral blind sacs will be described. In all steers liver abscesses will be scored. Hot carcass weights, carcass quality and yield grades will be recorded in all steers and will be conducted according to the Canadian Beef Grading Agency. Data will be analyzed to determine the effects of the explanatory variables as factors affecting mean ruminal pH, prevalence of ruminal acidosis, DUR, AREA, and G:F. (AU)