Ruminal Fistulation and Cannulation: A Necessary Procedure for the Advancement of Biotechnological Research in Ruminants

Abstract

Rumen content is a complex mixture of feed, water, fermentation products, and living organisms such as bacteria, fungi, and protozoa, which vary over time and with different feeds. As it is impossible to reproduce this complex system in the laboratory, surgical fistulation and cannulation of the rumen is a powerful tool for the study (in vivo and in situ) of the physiology and biochemistry of the ruminant digestive system. Rumen fistulation in cattle, sheep, and goats has been performed extensively to advance our understanding of digestive physiology and development, nutrient degradability, and rumen microbial populations. The literature reports several fistulation and cannulation procedures in ruminants, which is not the focus of this paper. However, this method questions the ethical principles that alter the opinions of certain animal groups or those opposed to animal experimentation. In this article, we analyze the objectives of fistulation and cannulation of ruminants and the care needed to ensure that the welfare of the animal is maintained at all times. Due to the ethical issues raised by this technique, several in vitro digestion methods for simulating ruminal fermentation have been developed. The most relevant ones are described in this article. Independently of the procedure, we want to point out that research carried out with animals is obliged by legislation to follow strict ethical protocols, following the well-being and health status of the animal at all times.

Effects of Management, Dietary Intake, and Genotype on Rumen Morphology, Fermentation, and Microbiota, and on Meat Quality in Yaks and Cattle

“…Several methods have been employed to collect rumen samples for determining relative abundances of microbiota, namely, via oro-ruminal tube (21)(22)(23)(24) and ruminal fistula (25,26), and collection from a slaughtered animal (5,27). The contents are often strained through cheesecloth and snap-frozen at −80 • C until analyzed.…”

Bovine Rumen Microbiome: Impact of DNA Extraction Methods and Comparison of Non-Invasive Sampling Sites

“…These being either the insertion of a gastric sampling tube into the rumen (rumenocentisis, the collection of rumen fluid by percutaneous needle aspiration), or via rumen fistulation of the animal, all of which have their limitations. The gastric sample tube can be susceptible to saliva contamination and can be difficult to know the exact location in which the tube is situated [16,19,20], and both rumenocentisis and fistulation can run the risk of external contamination of the sample, as well as needing close monitoring of the animal to avoid the occurrence of infection [21,22]. As such, a non-invasive sampling method that can be conducted in many animals would aid in this approach.…”

The Destruction of the Anaerobic Environment Caused by Rumen Fistula Surgery Leads to Differences in the Rumen Microbial Diversity and Function of Sheep

“…In practice, many animal trials and sampling methods leave these changes of microbial community wholly out of account. In some cases, comparing the sample of the oral tube and fistula on fistulated animals was equivalent to comparing with the sample of the fistulated or intact ( 15 , 17 , 18 ), which lacks sufficient evidence to provide proof. At present, figuring out the impact of fistula needs to unify three key variations: whether fistulated or not; whether it is the same group of animal before and after the fistula; whether a unified sampling method has been selected (oral tube or fistula).…”