Physicochemical Evaluations of Diets, Rumen Fluid, Blood and Faeces of Beef Cattle under Two Different Feedlot Systems

Simple Summary Mitigating the toll of nutritional disorders in feedlot systems can become difficult when the issue is not fully understood or correctly monitored. The physicochemical characteristics of diets and faeces were strongly correlated with digestive disorders in two distinct beef cattle feedlot systems. Ruminal and faecal pH, and particles size distribution in the faeces used in combination with information of the diet nutritional composition and fibrosity worked as good indicators for presence of digestive disorders. The use of these ancillary tests is proposed here as tools to facilitate best practice management protocols aiming to reduce the risks of subacute rumen acidosis. The physicochemical characteristics of diets and faeces were evaluated in combination with data of rumen fluid and blood lactate collected from two distinct feedlot systems in Brazil to understand the causes and correlations to digestive disorders in these production systems. The data were collected during two visits to a finishing system which fed about 80,000 head per year, and four visits to two properties that fed 150 to 180 straight bred Nellore bulls per year to be sold as stud cattle. The findings suggest that ruminal acidosis occurred when there was high intake of starch-rich concentrate, and that subacute rumen acidosis (SARA) most likely occurred in situations where more than 4% of faecal dry matter was excreted as particles larger than 4 mm. The latter were associated with diets having less than 15% of particles smaller than 8 mm and faecal pH under 6.30. It is concluded that ancillary tests, such as ruminal and faecal pH, and particle size distribution in the faeces, can potentially be used in combination with information on diet nutritional composition and a series of best practice management protocols to increase not only animal productivity but to reduce the risks of SARA and ensure the welfare of animals.