Ascites or Water Belly (Hypertrophy of the Right Ventricle, Pulmonary Hypertension ,) in Broiler Chickens during Winter Season
DR Surinder Khana, Poultry Consultant,Ambala
The term “ascites” actually refers to the fluid accumulated in the abdominal cavity (or “waterbelly”) as a consequence of heart failure. This fluid generally accumulates in ventral hepatic, peritoneal or pericardial spaces and sometime also contains protein clots. There may be many predisposing factors but ultimately the final cause leading to ascites is deficiency of oxygen.
During winter most of the farms use curtains to maintain temperature, same time there is use of wood, coal and gas as material for producing heat inside. The burning of these materials resulted in production of gases such as carbon dioxide and carbon monoxide. During last decade or so there is tremendous improvement in genetic potential of bird to grow at a very rapid pace. To meet this genetic potential the quality of feed given to the broiler bird has also been improved to many fold and enriched with highly digestible amino acid and metabolizable energy. This type of feeding results in higher production of Ammonia from the feces. With closed curtains gases such
as CO2, CO & NH3 started accumulating inside the farm while O2 concentration goes down.
During brooding stage the impact of this O2 deficiency resulted in damage of air sac. As bird approaches 4th week, the average growth rate goes up at rapid pace and the demand for oxygen also increase by many fold. Damaged air sac, closed curtains and high growth all combined together and hence birds not able to get the required amount of oxygen results in ascites syndrome.
In some cases due to temperature fluctuation or due to various stresses birds suffered from disease such as CRD or viral outbreak resulted in damage to respiratory system which hence could not able to support high demand of oxygen which again resulted in ascites
So going by these facts we can firmly confirm that broiler birds are vulnerable to ascites not only in winter but even during summer as well, although the incidence will be more during winter and especially in farms where there is improper ventilation & management.
Ascites (or water belly) is a condition of fast growing broiler chickens in which the excess amount of ascitic fluid accumulated in the abdominal cavity. It has become major concern to the poultry industry around the world. This condition is extremely common in high altitude & more particularly during winter / cooler season.
This physiological demand increase pulmonary arterial pressure (hypertension). Bird lungs have very little ability to expand and the blood capillaries in the lungs are not able to handle increased blood flow or blood pressure. The result is an increased pressure in the liver with leakage of blood fluids, without the red blood cells, into the body cavity forming ascites or water belly.
Following may be the cause of ascites (water belly):
- Today´s broilers grow much faster, eating less feed. The growth of the heart and lungs has not increased in size proportional to the increase in body weight and breast meat yield. The rapid growth of the bird means more oxygen demand, requiring more work out of the heart and lungs.
- Anything that limits oxygen uptake from the lungs is going to cause the heart to work harder. Diseases of the lungs and poor ventilation may be involved. Major cause of Oxygen deficiency :
a) Presence of ammonia in the poultry house. Birds are unable to get adequate oxygen as they inhale air full of ammonia so blood is deprived of oxygen supply.
b) The dust particle in the air of poultry shed are inhaled by the birds and while exhaling they settle in various part of air sacs, specially thoracic air sac where air stays for longer period which leads difficulty for birds to breath hence deficiency of oxygen in the blood.
c) Presence of high carbon dioxide level in the shed either due to overcrowding, poor ventilation, blocking fresh & cold air during winter with curtains or due to lack of proper exhaust fans results deficiency of oxygen in the blood of bird. - Excess levels of sodium in the water or salt in feed leads to increased blood pressure in the lungs. Many feed millers still use fish meal high levels of sodium. Levels of sodium over 400 ppm could cause problems in broilers.
- High altitudes have long been known to cause heart failure and ascites.
- Chilling is a common cause in small flocks. It causes an increased blood flow through the lungs
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I .Capillary endothelial damage which is caused by action of toxic substances such as: diotoksin, phenol, furazolidone. Furazolidone previously used in poultry and its application in poultry by us is prohibited. ii. Septikemic various conditions caused by bacteria and bacterial toxins that can damage the blood vessels with consequent release of plasma into the surrounding tissue. iii. Increase vascular hydrostatic pressure, which stimulates the release of fluid from blood vessels, is a common cause of ascites in heavy breed chickens and ducks due to damage to the right heart valve and the right ventricle as a result of hypertension. iv. Reduce vaskularmog koloidoosmotskog pressure leading to ascites, because there is not enough protein to keep the water bound for myself, and free water out into the surrounding tissue. v. Poor ventilation results in increased ammonia concentrations that lead to lung damage with subsequent hypoxia. vi. Overpopulation space leads to hypoxia due to inadequate concentration of oxygen in the air. vii. A vitamin E, vitamin C and selenium, which allows harmful effects of free radicals in the blood vessel walls. viii. sodium intoxication, which leads to the deposition of salt crystals in the kidney, resulting in the occurrence of ascites. ix. Erucic acid rapeseed degenerative effect on the cells of heart infarction, and thus hinders the work of the heart. x. Stress occurs at high or low temperatures, due to overcrowding in the facility, during transport, vaccination coverage of individuals. As a result of stress leads to an increase in blood pressure, and to the increased heart rate, which results in the damage of blood vessels . xi. Keeping the birds at high altitudes, although ascites occurs at all altitudes – Stay birds at high altitudes causes of secondary polycythemia, in which the increased viscosity (density of blood), leading to its slow flow and hypoxia. xii. Mikotoksikoze lead to damage to the liver, which does not synthesize sufficient albumins and other blood protein
Signs of ascites:
• High rate of panting is often observed in ascitic birds even the absence of apparent heat stress.
• Gurgling sound often accompany as they often just sit with panting.
• Birds which are ascitic may show sign of Cyanosis (a blue discolouration of skin) especially around comb & wattles.
• Ascitic birds tire out easy and often die on their bellies.
• Most death begins at about 3 weeks of age.
• If their belly is opened, a cup or more of fluid or jellied material will pour out.
• Lungs of ascitic bird may often appear pale or greyish. Lungs are extremely congested & oedematous.
• Liver enlargement is often seen.
• Thickening of right side myocardium & dilation of the ventricle are very common.
• Microscopic finding – increased cartilage nodules in lung.
• Sometimes birds die from the effects of too much blood and fluid in their lungs before there is any significant amount of fluid in the body cavity.
How to minimize ascites (water belly)?
• Keep air quality fresh by moving air regularly and efficiently. In the colder months, it is better to add heat and keep the air moving than to shut down vents or reduce airflow in an effort to conserve heat.
• Treat litter by “Liiteron” to reduce ammonia production. Litter treatment is important to reduce incidence of water belly.
• Restricting feed, feeding a mash diet, or using a less energy and protein diet.
• Checking sodium level of water, if sodium level is high then consider using an alternate source of water that is better quality for the first 3 – 4 weeks.
• Replace fish meals with other readymade source like amino acid arginine, if it is being used as Sodium level more than 400 ppm could be problem for broiler.
• Careful attention to brooding temperature is also critical for minimizing water belly.
• Prevent respiratory disease conditions.
• Select breeds which are not genetically susceptible to this condition.
The objective should be to minimize progression leading from pulmonary hypertension to terminal ascitis or water belly condition for availing better profit during winter season. Best Management Practice is only answer to reduce problem of Ascites (Water belly) and insure better ROI.
Prevention and Treatment of Ascites
Since we find signs of ascites, rapid mortality occurs and is impossible to therapy. In the case of a large number of cases of ascites, the losses can be reduced using the following measures i. Use of low energy food limiting diet. Moving from the finely ground pelleted feed. Reduce contamination of food with toxins to a minimum, increase vitamin E, vitamin C and organic selenium in foods. Reduce sodium levels in foods to 0.19%. ii. low outside temperatures lead to increased demand for oxygen, and it can be a trigger mechanism of ascites. It is especially important to take into account the temperature in the house in the first 2 weeks of life, because then the birds most susceptible to low temperature stress. For example, lowering the temperature to 10°C doubles the demand for oxygen . iii. Control of contamination of the air in the house. It is necessary to optimal ventilation to the concentration of harmful gases and dust in the air reduced to the minimum values. The most important thing is to pay attention to maximum permissible concentration of ammonia in the house, which is up to 50 ppm. The optimal concentration is 25 ppm of ammonia. Take into account the moisture mat, because when increasing its humidity leads to increased concentrations of ammonia. iv. Reduce the length of day light or light intensity, because in this way reduces food intake and activity
As been found out that growth rate is a key factor in the development of the ascites syndrome, so decreasing the growth rate of broilers by dietary manipulations is the first thing being suggested to control ascites. Diet mixed with grains such as maize, wheat can help in reducing the growth metabolism and hence will give time to the bird to recover. Same way use of Vitamin E and Selenium in the diet has been reported to have very good effect on controlling ascites issue. There are some additives available in the market which when used in the broiler diet help to control ammonia formation in the farm. But overall the best way to prevent ascites is by taking care of the management part at broiler farm especially ventilation because once birds get infected it become very tough to control. Few steps which can keep the broiler flock safe are mentioned as below
• Maintaining a consistent temperature
• Keeping optimum air quality
• Keeping litter moisture level at low level, also if reusing litter then consider using a litter treatment.
• By reducing stress in the flock
• Keeping optimum flock density.
• Making sure that feed is always available in feeder
• Keeping adequate feed and water space.
• Reducing light variation and keeping light levels at reasonable intensities
Some researchers have reported that feed restriction in the form of skip-a-day feeding programs have worked successfully to reduce mortality due to ascites syndrome. Although no depression in weight gain occurred when feed was restricted during the second week of life, feed restriction programs will result in depressed growth as high as 150 g/bird at 7 weeks of age.
Also supplementation of diet with Vitamin C has been reported to have beneficial effect if birds get affected with ascites.
So overall there is no available specific treatment for ascites syndrome. For broiler farmers one thing is quite necessary that they have to reduce stressors through any means. Some time it is difficult to focus on all the things at a time or correct all the management lapses completely but in such cases the best way is to take small steps towards improvement. As being taught that prevention is always better than cure, these words give a clear perfect message about what need to done to control this challenge.
Reference-On Request
