NAIROBI, KENYA: Mama Njoki is one of the most fervid poultry farmers I have encountered in my 12 years as a Vet.
Her poultry keeping passion started when she was in college about 30 years ago and ever since she has been keeping different species and breeds at any given time. One of the challenges she encounters in broiler keeping is a condition known as ascites syndrome — commonly known as waterbelly syndrome.
I visited her farm in Njoro, Nakuru about four months ago. I was delivering a batch of 400 improved kienyeji chicks she had ordered from my Naivasha farm. On that very same day, she had lost two mature broilers and since she knew I was on my way to her farm, she preserved the carcasses for me to do a post-mortem.
Heavy feeders
My PM findings revealed the following - clear yellow fluid with some clots of protein/ fibrin in the abdominal cavity also known as the peritoneal cavity, the liver was swollen, right side of the heart was enlarged with fluid as well. These are signs of waterbelly syndrome, common in broiler farms. This can be compared to heart failure in chicken and is sometimes referred to as pulmonary hypertension syndrome. Ascites refers to the accumulation of fluid or exudate in the peritonel cavity (abdominal space). This condition is common worldwide with occurrences being higher in high altitude areas or where supply of oxygen is insufficient. The syndrome is mostly common in fast growing broiler and turkeys.
Several factors including genes, breeding, nutrition, oxygen content in the air and the rapid growth rate have been documented as causes of the condition. One of the functions of oxygen in an animal is maintenance and development of cell health. Oxygen is essentially the fuel utilised during metabolic processes that take place in the body at the cellular level.
Broilers consume a lot of food- high energy food hence the rapid growth which in turn results in an increased demand for oxygen in the body tissues. A series of actions then takes place when the oxygen demand is amplified.
The lungs, being the primary site of gaseous exchange then requests for an increase in blood flow, so as to be able to dissolve more oxygen and transport it to the body tissues. This order is then forwarded to the heart to pump maximum amount of blood to the lung and by so doing increases the heart’s work load.
The right side of the heart is responsible for pumping blood to the lungs and when this function is compromised due to the heavy work load, it enlarges to meet the requirements. The resultant volume and pressure overload of the right side of the heart leads to dilatation and weakening of the heart valves which exacerbate the condition.
Blood pressure is therefore increased in the blood vessels returning blood to the heart. Excess blood is forced to flow back to the liver and intestines. As a result plasma —the colourless fluid part of blood — leaks out of the blood vessels into the peritoneal cavity. This yellow/ straw-coloured fluid in the abdomen is what gives the condition the name ‘waterbelly’. Ascites is often manifested as panting by the bird even though there is no heat stress. Ascites can be prevented by reducing the birds’ oxygen requirement. Broilers fed on pelleted food have higher chances of experiencing waterbelly.
Adequate temperature control of the broiler house, sufficient ventilation and efficient litter management reduce mortality from waterbelly. Since altitude can’t be changed, a lower energy feed and mash feeding instead of pellets should be adopted.
(The writer is a veterinary surgeon and runs Nature Kuku, a farm in Naivasha that produces kuku kienyeji breed and trains small holder farmers.
tonykiragu@gmail.com)
