CURRENT TECHNIQUES USED FOR CONDUCTING RUMEN EXPERIMENTS IN THE LABORATORY
Harneet Kour, Ph.D. scholar, Animal nutrition division, ICAR-National Dairy Research Institute, Karnal
Raman Malik, Principal Scientist, Animal Nutrition Division, ICAR-National Dairy Research Institute, Karnal
Parul Rana, Ph.D. scholar, Animal Nutrition division, ICAR-National Dairy Research Institute, Karnal
Aman Goyal, Ph.D. scholar, Animal Nutrition division, ICAR-National Dairy Research Institute, Karnal
ABSTRACT
India ranks first in cattle and buffalo population however for production nevertheless there is a variety of scope for development. All the production and control factors are associated with the rumen of the cattle species however nevertheless, it has now not been observed absolutely. Conducting experiments on live animals has grown to be a motive of problems due to ethical and economic issues. In this kind of scenario, laboratory techniques come into use for the estimation of numerous parameters associated with ruminants’ digestive system.
INTRODUCTION
Ruminants have stomachs with 4 chambers. The rumen is the largest compartment where thousands and thousands of bacteria grow underneath anaerobic (low oxygen) conditions. Those bacteria are liable for digesting nutritional fiber (cellulose) and are the purpose ruminants can consume an expansion of byproducts from processing flowers for human consumption. The dietary cost or strength content of a feed is determined mainly by means of its digestibility, which affects consumption, i.e., how a lot the animal eats. Digestibility and consumption, in flip, determine the manufacturing overall performance of the feed, e.g., to sell lactic synthesis or muscle increase. However, stay animal (in vivo) studies to decide feed digestibility are time-consuming, arduous, high-priced, and require big quantities of feed. Such trials are not suitable for the fast and habitual feed evaluations accomplished with the aid of business laboratories that provide feed statistics to livestock manufacturers
The idea of artificial rumen has been developed for appearing recurring laboratory experiments without animal testing. There are a diffusion of different synthetic rumen analogs, starting from easy gas series rumen systems that may run for approximately 96 hours (quick term) to complicated RUSITEC structures which could run constantly for months (long time). The main distinction between a brief and long-term machine is that the fast gadget gets a fixed quantity of buffer and feed to keep the microorganisms for about 72-96 hours, while a long-time period system is constantly fed with a regular supply of artificial saliva and non-stop elimination of waste material. Both systems are flexible, from measuring gas formation in one-of-a-kind feeds to reading the digestibility and durability of components and drugs in a rumen environment.
IN VITRO TECHNIQUES
This approach of feed evaluation was first mentioned in 1963, the use of rumen juice from a sheep with a rumen fistula (Tilley and Terry, 1963). The digestibility of feeds can also be anticipated through the use of organic methods referred to as in vitro strategies, that are accomplished outside the animal system but simulate the digestive procedure. Usually, in vitro methods are based totally at the measurement of fermentation residues or merchandise. In the former, the unfermented residue closing after in vitro incubation of a feed with rumen liquor is measured. Gasoline size methods have been routinely used in feed assessment since the early 1980s whilst an excessive correlation became determined between metabolizable energy measured in animals (ME) and strength expected from gas production. The in vitro fuel approach has several advantages over other in vitro strategies based on residue measurement. This method includes the subsequent steps:
- The guide extraction of rumen liquor from the rumen of a rumen-fistulated animal. The manual extraction of rumen liquor from the rumen of a rumen-fistulated animal. A rumen fistula is shaped via surgically slicing the skin and rumen, suturing the rumen to the skin, and permitting the rumen to heal, creating an everlasting commencing into the rumen. A tender cannula is inserted into the fistula to close the rumen.
- 375 ± five mg of complete feed is weighed in stability. After weighing, the sample is cautiously positioned within the backside of the calibrated 100 ml glass syringe.
- To allow the plunger to transport smoothly inside the barrel, it is greased with petroleum jelly.
- The syringes, containing the pattern in triplicate, are saved in a water bath at 39℃ for 24 hours.
The material now not recovered within the residues after incubation is assumed to be fermented, so estimates of the quantity of digestion for different feeds are feasible. Rumen fermentation via anaerobic microbes results in the manufacturing of short-chain fatty acids (SCFA), gases (carbon dioxide [CO2] and methane [CH4]), and microbial mass. The quantity of gas produced is proportional to the acid manufacturing and therefore serves as an indicator of the acids produced via the fermentation. The quantity of gas produced for the duration of incubation is measured to expect the quantity and amount of feed digestion.
GAS SERIES RUMENS (GCRS)
One of the synthetic rumen strategies evolved by way of Ridgeway studies, United Kingdom, turned into gas series rumen. This approach became used to measure the quantity of gas produced by way of exclusive feedstuffs. It’s a laboratory approach of evaluation that includes the usage of simple glassware to measure the quantity of gas produced by means of extraordinary substances. One of the essential goals is to study methane production, and how it could be reduced to prevent weather exchange. Gases also can be analyzed within the float to signify the gas produced and determine how the feed samples have an effect on the output. Different parameters that can be studied for the use of GCR are pH, unsaturated fatty acids, and ammonia production but those can be used only for a short time period. It could also be used by the pharmaceutical industry for testing various drugs (Ridgeway Research, 2022).
RUMEN STIMULATION METHOD (RUSITEC)
The RUSITEC has been gift for decades and is now a properly-mounted and tested in vitro version. RUSITEC system is semi-continuous and because of this, it can run for weeks or maybe months with little downtime. They’re extremely useful for investigating ruminal fermentation, digestion of feedstuff, gases produced, the microbiota of the rumen, metabolism modifications, and the breakdown and precipitation of prescription drugs. The primary benefit of a RUSITEC in comparison to a GCR is that a RUSITEC can run for longer intervals of time, that is in part due to the persistent feed of artificial saliva and a regular runoff of waste cloth. Also, the RUSITEC system minimizes animal variability in the same manner the GCR does. Despite the fact that being a distinctly standardized approach (e.g., In temperature, pH and buffer flow) the device is understood to differ from in vivo conditions regarding absorptive processes, differences in the ratio between liquid and solid materials, lower short-chain fatty acid (SCFA) concentrations and protozoal shifts compared to the donor animal.
ADVANTAGES OF ANALYSING RUMEN PARAMETERS IN THE LAB:
- These methods can used for quantifying the chemical composition of feeds and in vitro feed digestibility.
- This data generated can be used in new ration-evaluation computer models with the goal of optimizing nutrient utilization and animal productive performance, thereby minimizing the environmental impacts of nutrient excretion in the animal’s urine and feces.
- Gas production reflects all nutrients fermented, soluble as well as insoluble; and fractions that are not fermentable do not contribute to gas production.
- Furthermore, the kinetics of fermentation can be obtained from a single incubation, allowing the rate of fermentation to be calculated.
- Gas measurement is a direct measure of microbial activity and can be a better index of forage ME content than an indirect in vitro measure based on nutrients fermented.
- Reduction in cost due to the expensive nature of purchasing ruminants, reduction in animal use for scientific purposes, eliminating animal variability and it is often easier to set up and more convenient.
DISADVANTAGES OF EXISTING LABORATORY TECHNIQUES:
- There are still some differences between in vitromodels and in vivo studies, this is in regards to absorptive processes, liquid and solid material ratio differences, lower short-chain fatty acid concentrations, and protozoal shifts.
- There are disadvantages of a RUSITEC, the main one being that the equipment is expensive to purchase and maintain.
- In a similar way to the GCR the liquid effluent and/or gases can be collected and analyzed downstream in relation to the experiment taking place.
CONCLUSION
The use of artificial rumens is a hot area of research; there are other types of artificial rumen currently in development in the industry to advance the technique, such as dual flow continuous culture but more research and development is required in this area.
