In situ and in vitro methods used to evaluate food and diets of ruminants

Abstract

In ruminant production systems, feeding can account for 60 to 70% of the costs of the activity, thus, the nutritional assessment of food and the formulation of balanced diets that meet the requirements of animals represent an important challenge in livestock production. Several methods have been used to evaluate the modulation of rumen fermentation and to estimate the degradation characteristics of food and diets intended for feeding ruminants. These methods involve measuring the disappearance of the substrate during incubation in the rumen (in situ), in the buffered rumen liquid (in vitro) and are mainly endpoint measurements. In addition, it is possible to evaluate the degradation kinetics by measuring the differences in residues at different incubation times. The assessment of the nutritional value of foods and diets is also possible through the use of techniques that measure gas production. These techniques measure the appearance of rumen fermentation products, such as carbon dioxide (CO2) and methane (CH4) gases, short-chain fatty acids, ammonia and microbial biomass. The aim of this review was to describe the main in situ and in vitro methods used to evaluate food for ruminants.