Definition, symptoms and prevention methods
Today’s dairy cattle are genetically prepared to produce large amount of milk. Along with that is the requirement for the consumption and digestion of large amounts of feedstuffs. The incidence of displaced abomasa (DA) may be increasing in our dairy herds via both genetic selection for greater milk production and the shift to more energy dense diets that may have less effective fiber content. Approximately 5% of high producing dairy cows may have a displaced abomasum.
Definition of abomasum
The abomasum is the ruminants “true” stomach and comparable to the stomach in monogastric animals. It is not a small organ as it can contain 27 L of fluids; however it is dwarfed by comparison to the 180+ L in the rumen-reticulum.
Located on the right side and along the bottom of the rumen, the abomasum can undergo movement or position changes due to changes in rumen fill or the size and place of internal organs. Key to abomasal displacements are changes due to calving and feed intake.
The more time the rumen remains filled, the less opportunity is there for the abomasum to shift. However, at calving there is a great void in the cow with the loss of the calf, placenta, and associated fluid. Organs shift in location and the abomasum can slip from its normal position. Additionally, cows often have reduced feed intake associated with calving which can also make it easier for the rumen to slip from its normal position.
Ketosis that occurs during the first months of lactation can also contribute to decreased feed intake and an increase in the incidence of displaced abomasa. About 80% of the displaced abomasum cases occur within the first month of lactation. A left displaced abomasum where the abomasum slides up the left side of the rumen is the most common and accounts for 80% of displacements.
The first signs of abomasal displacements in cattle are:
- Decreased feed intake
- Listless behavior
- A drop in milk production.
- The amount of feces produced may be reduced and have more fluids than normal.
The heart and respiration rates may remain fairly normal. The most diagnostic test is usually the “ping test”. Using a stethoscope one can hear a ping as a result of thumping the area. As the abomasum is displaced, gasses tend to build as regular flow is decreased due to twisting of the duodenum. Occasionally, displaced abomasum can be corrected by “rolling” the cow or jogging the cow to encourage the organs to resume their normal position. On a practical basis, by the time a cow is observed and a displaced abomasum is suspected, surgery is the likely outcome. The surgery can be done with minimally invasive techniques, but all surgery has a risk and the cow will still have a recovery period of poor production—or if treated with antibiotics—disposed milk.
The best prevention is consistent feed intake. Rumen fill and continuous flow of material helps maintain both rumen and abomasum in their proper position. Unfortunately, there are times when consistent intake is not possible. In addition to the issues surrounding calving, cattle can go off of feed because of disease, mycotoxin challenges, and diet changes. Even weather can effect intake. Certain management decisions can reduce the interruptions to feed intake (Table 1).
Tips for maintaining feed intake:
|Have a transition program that encourages feed intake and rumen fill. Numerous studies have demonstrated that the less a cow’s feed intake drops at calving, the more quickly they will increase dry matter intake after calving.|
|Encourage feed intake through the use of better quality forages.|
|Consider adding yeast supplements or yeast culture products into the ration. Yeast products can support fiber digestion and feed intake. Yeast culture products have also been used as palatability enhancers.|
|Maintaining this feed intake is critical to reducing both clinical and subclinical ketosis. Ketosis is known to result in reduced feed intake and explains the increases in DA associated with it. Additionally, a reduction in rumen motility can be related to DA.|
Fiber length and proportion of the diet can influence DA. A lack of fiber can result in lower rumination and decreased filling (to keep the rumen in its normal position). At the same time, high producing dairy cows need energy. Fiber sources that have good digestibility or the addition of yeast-based products which may assist fiber digestion can help in both meeting the need for fiber and the greater energy need of these cattle.
Displaced abomasa are becoming more common in dairy operations as a combination of changing genetics and feeding programs. Management and feeding programs that help ensure rumen fill through good dry matter intake and reduce energy deficits should help reduce the number of observed displaced abomasa.