CANNULATED OR FISTULATED COW:AN IMPORTANT TOOL FOR RUMEN TRANSFAUNATION & RESEARCH ANALYSIS OF THE DIGESTIVE SYSTEM
COMPILED BY -DR AMIT BHARDWAJ, VET.SURGEON,PUNE
A fistulated cow is a cow with a passageway (Cannula) connecting the cow’s rumen (stomach) to the outside. By creating this opening into the cow’s stomach, one can learn, for example, how a cow’s stomach works, about the microflora in the cow’s stomach, and how fast certain foods are digested. Immature cows are not ideal candidates because the cannula site expands in size as the cow continues to grow, causing leakage and drainage around the fistula.
WHAT IS A CANNULATED COW?
The cannula acts like a porthole and gives direct access to the cow’s rumen.Once the cannula is surgically placed in the cow, the animals grazes for a set period of time before being examined.Farmers remove the plug and pull the grass and oat mixture from the rumen.This material is collected and tested and this analysis shows farmers and researches which forages get the best results from the livestock, based on how much is digested.The practice is said to have become common place in the 1920s but reports of cows being used in this way for scientific research date back to 1833.Cows with cannulas fitted are also known as fistulated cows.
A cannulated cow or “fistulated cow” refers to a cow that has been surgically fitted with a cannula. A cannula acts as a porthole-like device that allows access to the rumen of a cow, to perform research and analysis of the digestive system and to allow veterinarians to transplant rumen contents from one cow to another.The practice of rumen cannulation was first documented in 1928 by Arthur Frederick Schalk and R.S. Amadon of North Dakota Agricultural College.
Rumen transfaunation involves the collection of rumen fluid from a healthy animal that will be transferred to a sick recipient animal. The following is a description of what might be described as best management practices for transfaunation.
Surgical implantation
Cannulation requires installing a flanged rubber cylinder in the side of a cow, behind its 13th rib. The cylinder typically is fitted with a plastic, rubber, or metal cap to keep the rumen anaerobic.
The rubber cannula is surgically implanted while the cow is standing and awake, with local anesthetic. The cow is made to fast and refrain from drinking water for 24 hours in advance of the surgery. Then the veterinarian excises a small piece of the cow’s skin, makes an incision through the rumen, and stitches the open sides of the rumen to the edges of skin, to prevent the contents of the rumen from leaking into the rest of the abdominal cavity.. Finally, the inner flange of the cannula is pushed inside the rumen and capped.
Reasons for cannulation
Cannulas are typically implanted in healthy cows to research cow digestion in a university setting, to analyze the nutritional quality of feed in an agricultural setting, or to improve the microbiome of a cow with digestive disturbance in a veterinary or agricultural setting.
Digestive research
By analyzing the chemical composition of a cow’s rumen, researchers can determine the effects of different feeds and processes on bovine digestion. Many of the earliest documented reports of cannulated cows were made by researchers working to understand how feed is processed through cows. For instance, a 1939 study discovered via cannulated cows that the pH of rumen varies throughout the day, becoming most alkaline just prior to feeding. A 1956 study used cannulated cows to determine that a hay-only diet does not change the proportion of fatty acids in a cow’s rumen, but every other type of feed measured does.
Forage analysis
Measuring the composition of a cow’s rumen can also indicate the quality of its feed, a process called a forage analysis.Once the cannula is surgically placed, the cow is then allowed to graze for a certain period of time—for example, 30 to 45 minutes, in a 1960 study at the University of Nevada, Reno. Researchers will then remove some or all of the ruminated material through the cannula. Analyzing rumen this way can indicate whether particular grasses on which cows are grazing are nutritionally adequate.
Transfaunation
Veterinary schools, veterinary hospitals, and bovine farming operations in North America often keep a healthy fistulated cow as a microbiota donor. Large animal veterinarians will pull the contents by hand from the healthy cow’s rumen system to help repopulate the fauna in a sick cow’s rumen. This process is called transfaunation, or a microbiota transplant.In Europe, the fistulation of cows to provide rumen contents for transfaunation is considered unethical, and is not practised. Instead, rumen liquor is aspirated through a rumen-fluid collector, consisting of a Frick gag and a flexible hose with a perforated metal tip which serves as a filter. The hose and tip is passed through the gag and down the oesophagus to the rumen. It is normally possible to aspirate five litres of rumen liquor using this device.Rumen contents from a fistulated cow can also help sheep and goats, which have similar digestive systems .A 2014 review of rumen transfaunation research indicated that the procedure has been demonstrated to help correct indigestion resulting from illness, surgical correction of displaced abomasum, and ingestion of toxic plants.
Collection of rumen fluid
Source cow
Collection of large volumes of rumen fluid is most easily accomplished using a rumen fistulated animal. Removal of rumen fluid is less stressful when the donor is fistulated than by stomach tubing a non-fistulated donor. Typically fistulated animals are housed and managed within the herd so there is limited risk of introducing unknown diseases and the rumen fluid reflects the diets fed on the dairy.There are reports where rumen fluid was obtained during abattoir slaughter or at post mortem. However, using a non-screened donor from an abattoir may introduce infectious agents, for example Mycobacterium avium var paratb, salmonella, Cryptospordia or E. coli (0157:H7).
Volume
Recommendations vary from 8 to 16 liters for adult cattle and 1 liter for calves. In our research at University of California – Davis, we used 10 to 11 liters of strained rumen fluid for adult cattle.
Timing
Rumen fluid should be transferred as soon as possible after collection. However, recommendations in the literature vary from within 30 minutes of collection to storage for up to nine hours at room temperature or for 24 hours at refrigeration temperature. In one study, storing rumen fluid under CO2 at 0oC for three to six hours did not affect fermentation characteristics; in another study, storing at 0oC for 24 hours decreased fermentation characteristics. Best practice would be to transfer the rumen fluid as soon as possible.
Ph
The pH of the rumen fluid should preferably be 6.0 or greater. This can easily be tested with pH paper. Rumen protozoa are decreased at low pH. Typically rumen fluid pH is lowest two to four hours after feeding with high starch diets that are fed to lactating cows, so avoid collecting rumen fluid within about four hours of feeding when the donor is receiving forage and concentrate ingredients used in lactating cow diets. With non-lactating cows that are fed a high forage diet, rumen fluid collection from a fistulated cow can be done prior to feeding or about two to three hours after feeding since pH does not change as dramatically with high forage-based diets and non-lactating cows are consuming less total dry matter than lactating cows. When using lactating cows with rumen fistulas, rumen fluid collection prior to feeding will likely provide rumen fluid above 6.0 pH.
Filter
Filter or strain large particulate matter from the rumen fluid using a screen (authors’ recommendation) to remove large particles that can plug the stomach tube. The filtered material should contain small particles and their associated attached bacteria, protozoa and fungi, along with the microorganisms that are associated with the liquid portion.
Color
Color of normal rumen fluid varies between olive to yellow-brown depending on the diet. One should avoid using foamy or frothy rumen fluid for transfaunation.
Microscopic examination
Microscopic examination of protozoa can be performed prior to transfaunation. Protozoa are visible using a transition microscope. In healthy rumen fluid, the ciliated protozoa should be motile. Microscopic evaluation of rumen fluid is generally impractical on a farm because of the time and labor needed for examination. Microscopic evaluation, in fact, is likely of little importance when the rumen fluid is transferred soon after collection.
Methylene blue test
Rumen fluid is highly reductive, so consequently, addition of methylene blue to the fluid and timing the change of color from its normal blue (oxidized) to a colorless state (reduced) can serve as an indirect measure of viability in the harvested rumen fluid. The test is performed by adding 0.5 ml of a 0.03 percent methylene-blue solution to 10 ml of rumen fluid in a test tube followed by mixing. A healthy rumen environment is highly reduced (high [H+] concentration). The blue color of the methylene blue should disappear within about five minutes or less. If it takes longer than 10 minutes for the color to disappear, it is probably best to discard the rumen fluid. Methylene blue has more application as a test of quality if the rumen fluid is stored for periods of time prior to transfer to the recipient.
SOURCE-PD, E.J. DePeters and L.W. George ,https://www.progressivedairy.com/
Standard Operating Procedure for Rumen Fistulation in Dairy Cattle
- Pre-operative Care • Cows should be examined to be sure there is sufficient space for the cannula between the last rib and the tuber coxae. • Feed and water are not withheld prior to surgery. •
- Surgical Preparation • The left paralumbar fossa is prepared for aseptic surgery by clipping with a #40 blade, followed by two to three scrubs with Betadine surgical scrub prior to the administration of regional anesthesia. • Regional anesthesia is obtained by administering 2% lidocaine in a paravertebral block to T13, L1, L2 and L3. • The skin in the surgical area is then scrubbed with Betadine surgical scrub and swabbed with Betadine solution and 70% alcohol.
- Surgery • The diameter of the plastisol cannula is roughly measured using suture material attached to a cutting edge needle. The site for the fistulation is chosen so that the flange of the cannula does not impinge on the transverse processes of the lumbar vertebrae, the tuber coxae and/or the last rib. The skin incision is mapped with the suture needle to the correct circular diameter. • The circular section of skin is removed. A circular incision is made in the external abdominal oblique muscle, slightly smaller diameter than the skin incision and this section removed. All blood vessels are ligated for hemostasis. Hemostasis in this area must be strictly maintained. The internal abdominal oblique and transversus abdominal muscles are separated in the direction of their fibers by blunt dissection. The peritoneum is incised. The rumen is elevated into the incision. The caudal dorsal sac of the rumen is identified and a site chosen for fistulation based on vascular pattern of the rumen. The rumen wall is sutured to the skin using four horizontal mattress retention sutures and simple interrupted sutures using non-absorbable, non-capillary suture material.
4.Post-operative Care
Cattle will receive 1 dose of Flunixin meglumine immediately following surgery. The animal is monitored daily for appetite, body temperature and condition of the incision.
- Placement of the Cannula • At day 4-6 post-operative, when the adhesion of the skin and rumen wall is judged to be firm, the wound is cleaned and the retention sutures removed. A circular section of the rumen wall is removed and a 3″ plastisol cannula placed in the fistula. • The incision is examined and cleaned as needed until healing is complete. As soon as healing permits, a 4″ plastisol cannula is placed in the fistula. 6. Long Term Maintenance Upon completion of the healing process, care of the animals and cannulas become the responsibility of the principal investigator in accordance with IACUC Guideline XII.
Cannula Preparation –
Several companies manufacture rumen cannulas. Flexible rumen cannulas are manufactured by The Bar Diamond Companya and John Morris Scientific\ and rigid rumen cannulas are available from John Morris Scientific and Macam Rubber. c The use of a flexible cannula a will be described within this article. Although insertion would vary, the surgical approach would be the same with another company’s product. Cannulas of different sizes are available, and care should be taken to match donor size with the size of cannula to prevent rubbing or loss of the cannula. The diameter of the center of the cannula should be measured, and then submerged in hot water until pliable. Remove from the hot water, and while still hot and pliable, reach through the center hole and pull the inside flange into the lumen of the cannula. Do not completely turn the cannula inside out. Return it to a hot water and antiseptic solution until the donor is prepared.
Pre-surgical Procedures—
The donor should be held off feed for at least 24 hours, and off water for 12 hours, prior to surgery. This results in less rumen fill, thus making the rumen wall more accessible and flaccid, allowing for easier exteriorization. Rumen contractions will also be decreased, resulting in less movement of the rumen during surgery. The surgery is performed with the animal standing, with adequate restraint provided. The left PLF is clipped dorsally from the transverse processes, ventrally to the flank fold, caudal to the tuber coxae and cranially to the 12th rib. The clipped area is then prepared with a surgical scrub, and regional anesthesia administered with a paravertebral, inverted L or line block using 2% lidocaine solution. Sedation of the patient is generally not required. We typically administer ceftiofur 30 minutes prior to surgery.
Surgical Technique
Location of the fistula is important to prevent unnecessary rubbing and skin erosion by the cannula. The appropriate area for the fistula is in the dorsal half of the left PLF, approximately 4-5 inches (10-12 cm) ventral to the transverse processes, and centered between the 13th rib and the tuber coxae. This location should allow room for the outer ring to sit within the PLF, and not rest on the transverse processes, the ribs, or the tuber coxae. The circular area of skin to be excised should be marked with a permanent marker prior to making an incision. The authors use a cup 0.5 inch (1.3 cm) smaller in diameter than the inside diameter of the cannula as a pattern (Figure 1). An incision is made along the marked area and the circular portion of skin removed (Figure 2). Using a hemostat, the external abdominal oblique, internal abdominal oblique and transverse abdominus muscles should be gridded to expose peritoneum (Figure 3). It is critical that the skin incision is not too large for the selected cannula in order to prevent the cannula from slipping out of the rumen and to maintain an anaerobic rumen environment. Gridding the muscle layers aids in securing the cannula in the abdominal wall, as the muscles contract post-surgery toward their original locale in a circular fashion around the cannula. Once peritoneum is exposed, it should be punctured, avoiding the underlying rumen. The peritoneum is then manually gridded to a size equal to that of the opening in the musculature. There is no need to suture the peritoneum to the external abdominal oblique. The next step is to grasp the rumen with sterile 4X4 gauze pads, and apply a pair of Allis tissue forceps to the rumen wall. Towel clamps may be employed here, but care must be taken to avoid entering the lumen of the rumen, thus potentially contaminating the surgical site. At this point, the rumen should be exteriorized, and secured to the skin by placing horizontal mattress sutures (four total) at the dorsal, ventral, cranial and caudal margins of the incision (Figure 4). Size one (1) chromic catgut is used for these sutures, and can be removed following completion of the surgery. These stay sutures are placed partial thickness through the rumen to prevent possible contamination of the body wall. Once the rumen is secured to the body wall, the rumen wall should be exteriorized to encompass an area approximately equal to the inner circumference of the cannula. This allows complete circumferential suture placement without stretching the rumen wall. The ventral half of the exposed rumen is then incised, and sutured to skin using a continuous everting pattern with size #2 absorbable suture, starting at the cranial aspect of the skin incision (9 o’clock) and continued ventrally (6 o’clock) to the caudal aspect (3 o’clock; The dorsal half of the rumen is then incised dorsally, and secured to the skin in an everting pattern consistent with that done for the ventral portion (Figure 6). The stay sutures should then be removed. Once the rumen has been sutured to the skin, the cannula is removed from the hot water bath. Water is used to lubricate the cannula prior to insertion. The cannula is inserted into the rumen by advancing the conical flange through the fistula (Figure 7), reaching into the center of the cannula, and then everting the flange into the lumen of the rumen (Figure 8). This secures the cannula in place (Figure 9). The final step is to insert the stopper into the cannula, which is easier to do if the stopper and center of the cannula are first lubricated with mineral oil.
Post-surgical Care —
The surgical site and the surface of the cannula’s outer rim next to the skin should be cleaned daily for fl.veto-seven days with a dilute antiseptic solution. Approximately 10 days post-surgery, remove the cannula by reaching through the center of the cannula and pulling the inner flange into the center. A necrotic ring of rumen tissue and any remaining suture material should be removed from the edge of the fistula. Once the wound is cleaned, the cannula is replaced. Bimonthly cleaning is sufficient after that. The wound should be protected from flies, and a broad spectrum antibiotic should be administered for seven days following surgery. We do not routinely administer postoperative analgesics, but a non-steroidal anti-inflammatory drug, such as flunixin meglumine, could be used if the animal appears uncomfortable.
Transfaunation—
Transfaunation is the removal ofruminal fluid and microbes from one animal, and transfer of that material to a different animal. The primary cause of abnormal ruminal flora should always be identified and corrected prior to transfaunation. The rumen environment must be receptive and conducive to microbial life prior to introduction of new microbes. A rumenotomy and evacuation of ruminal contents may be necessary in some cases, while high doses of oral antibiotics may suffice to remove abnormal microbes in others. An appropriate amount of rumen fill is necessary to stimulate motility if evacuation is performed, therefore feedstuffs must be placed into the rumen along with the transfaunation. Alfalfa pellets, soaked with water to make a mash, are easily administered via a stomach tube and provide nutrients for microbes to utilize. Longstem hay may also be introduced through the rumenostomy site prior to closure. One quart ( ~ lL) of rumen fluid is adequate to transfaunate ruminating calves, and a minimum of three quarts (~3L) should be administered to adult cattle.2 Transfaunation should be repeated daily until the animal’s appetite improves and fecal production returns. Rumen fluid for transfaunation purposes can be obtained from an abattoir or from a cannulated animal. Transfaunate is best when used immediately following collection, but contains viable organisms for up to nine hours at room temperature, and for 24 hours if refrigerated.
Treating dairy cow indigestion with rumen transfaunation
SOURCE-E.J. DePeters and L.W. George
Rumen transfaunation is a common practice to treat simple indigestion of dairy cattle. Transfaunation refers to transferring a broad spectrum of micro-organisms including bacteria, protozoa, fungi and archaea from the rumen of a healthy donor animal to the rumen of a sick recipient animal. The recipient animal can be one that is experiencing simple indigestion as well as an animal following correction of a displaced abomasum.
Ruminants are animals with a four-compartment stomach including the rumen (largest compartment), reticulum (honeycomb lining), omasum (many folds) and abomasum (gastric compartment). The rumen is a large, continuous anaerobic fermentation vat.
Micro-organisms living in the rumen allow ruminants like the dairy cow to digest the fibrous components of feed. The rumen functions in coordination with the reticulum to support contractions of the musculature that create the functions of rumination (cud chewing and rumen contractions) and eructation (gas release).
The dairy cow can be considered as a super-organism because it has a symbiotic relationship of life between the cells of the animal’s body and the rumen microbes. Factors affecting the viability of micro-organisms in the rumen, as well as anywhere along the gastrointestinal tract of the ruminant, impact the host animal.
Feeding the dairy animal means you are feeding the micro-organisms in the rumen, so digestive upsets are a result of disturbances to the normal fermentation balance of microbes in the rumen.
Establishment of a microbial population in the rumen occurs quickly following birth in ruminants. The rumen of a newborn calf is faunated by its mother when she licks the calf as well as from the micro-organisms living in the environment around the calf. Microbial inoculation of the rumen occurs soon after birth to contribute to the development of a healthy ruminant.
Rumen transfaunation was a common practice centuries ago, well before our understanding of bacteriology and rumen micro-organisms. Farmers in the 1700s were reported to have transferred the cud from a healthy donor animal to a sick recipient animal as a practical method of treatment for indigestion.
In the 1900s, scientists began to study the effects of inoculation with rumen fluid on rumen development in young calves. These studies contributed to our current understanding of the diverse rumen population of micro-organisms that thrive in a community of living organisms that is highly competitive.
Applications of rumen transfaunation
Indigestion in dairy cattle reduces rumen motility and kills rumen microflora. Simple indigestion can be associated with sudden changes in dietary ingredients (e.g., transition period) or with anything that alters the consistency of the feeding program.
Such changes could include heat stress, feeding moldy feed, interruption of water sources or in situations where carrying capacity of pens exceeds headlocks. Competition for feedbunk space leads to slug feeding, sorting of feed ingredients and then to indigestion.
Dairy farmers should consider simple indigestion whenever multiple cows have a sudden onset of reduced appetite, whenever there is a sudden and otherwise unexplained drop in milk production or when cows develop diarrhea with undigested grain kernels.
Even though transfaunation of rumen fluid from a healthy donor animal to an animal with simple indigestion is a common, recommended practice for dairy cattle, there is little scientific information on the practice. Rumen transfaunation was successfully used in a clinical research setting with sheep that experienced simple indigestion associated with change of diet with fasting prior to surgery, shipping and handling stress. Rumen transfaunation of sheep post-operatively corrected simple indigestion.
Simple indigestion can be an issue during early lactation of the transition period when dietary changes require dairy cows to adjust to diets high in nonstructural carbohydrates that ferment rapidly in the rumen.
During the transition period around calving, cows experience not only diet changes but also physiological changes associated with parturition that can be exacerbated during periods of high environmental temperatures. During the transition period, cows are also moving from different pens, so social structure is changing, and this can be a stressor.
We conducted a field study to evaluate rumen transfaunation in the transition period of dairy cows. Four ruminally fistulated, lactating dairy cows receiving a TMR were used as donor animals. These four ruminally fistulated cows were managed similar to all other lactating cows and were provided no special considerations by the staff.
Rumen fluid transfaunation was one of four treatments applied where 11.4 liters of rumen fluid were transferred by oral stomach tubes into the rumen of fresh cows (donor cows) approximately 24 hours post-calving. Treatments were: control – no oral supplement, warm water via stomach tube, commercial product via stomach tube and rumen fluid via stomach tube.
The hypothesis was that rumen fluid transfaunation would improve the health of cows after calving. Compared with control, all oral treatments did not affect serum blood analytes, milk yield and animal health in a well-managed herd. A study involving a herd experiencing problems with simple indigestion might show a beneficial response.
Typically at the University of California – Davis dairy, we will transfaunate a sick cow one time with rumen fluid. But there are animals that do require a second (12 to 24 hours later) and even a third transfaunation (24 to 36 hours later).
Rumen transfaunation was used as an adjunctive treatment following surgical repair of left-displaced abomasum (LDA) at the large animal clinic of the School of Veterinary Medicine at University of California – Davis. Rumen fluid (10 liters) obtained from two non-lactating, ruminally fistulated donor cows fed a forage diet (predominantly hay) was transferred by stomach tube (oral) within 20 minutes of rumen fluid collection to cows following surgery.
Control cows received only 10 liters of lukewarm tap water (no rumen fluid), also by stomach tube. Rumen fluid treatments occurred immediately following surgery and again on day 1 after surgery. Beginning on day 2, following surgery and for the next three days, rumen-transfaunated cows had higher dry matter intake and milk yield compared with control cows.
Rumen fluid pH and total concentration of volatile fatty acids did not differ for day post-surgery or between rumen-transfaunated and control treatments. Serum concentrations of beta-hydroxybutyrate on days 3 and 5 post-surgery were significantly lower in transfaunated cows than control cows. The authors concluded: “Administration of rumen fluid to cows convalescing after surgical correction of LDA had beneficial effects.”
Intrinsic aspects of transfaunatation
Even though we tend to think about the micro-organisms, rumen fluid contains many chemical constituents that likely contribute to the beneficial effects of transfaunation. Such factors include volatile fatty acids, bicarbonate buffers, proteins and amino acids, as well as many unidentified constituents in rumen fluid. These chemical entities might all stimulate microbial growth.
Early researchers observed that branched-chain fatty acids stimulated the growth of cellulose-digesting bacteria. Thiamine, a B vitamin, produced by one organism stimulated the growth of other organisms.
These are just a few examples of how complex the rumen environment is and how interlinked the micro-organisms can be. The nutrients in rumen fluid transfaunate will likely benefit the growth of bacteria, protozoa, methanogens and fungi to restore normal microflora populations in the sick recipient.
The effects of mechanical stimulation by bulk activity of the transfaunate may also be beneficial. Transfaunation with 8 to 16 liters of rumen fluid in cattle could induce mechanical stimulation of tension receptors in the walls of the rumen and reticulum to stimulate rumination, salivation and normal rumen motility.This illustrates that the impacts of rumen transfaunation are broader than just the micro-organisms.Rumen transfaunation is a routine, widely accepted, successful procedure to treat simple indigestion in ruminants. The procedure also has clinical application for post-operative treatment of cattle with left-sided abomasal displacements.Rumen fluid from a healthy donor provides the recipient with diverse micro-organisms that can repopulate the rumen. Transplanted rumen fluid also provides nutrients and energy to support a healthy rumen microbial population.
REFERENCE-ON REQUEST
https://www.pashudhanpraharee.com/keynote-on-ruminants-digestive-system-physiology/
https://www.progressivedairy.com/
