Sudden death syndrome in poultry

Sudden Death Syndrome in Poultry

Sudden death syndrome (SDS) is a condition affecting fast-growing birds. Death usually occurs within one to two minutes and the dead birds are frequently found lying on their backs. Because of this, the syndrome is also called flip-over disease. Affected birds do not show any specific signs of disease, and diagnosis is usually made by excluding other diseases. Numerous nutritional and physiological factors may lead to SDS.

  1. Environmental factors

Poor management of a flock can cause stress in birds. Any environmental stress (e.g. high light intensity, high stocking density, sudden noise, etc.) may influence the incidence of SDS, especially in fast-growing birds. Stress can increase the release of catecholamines (a type of neurohormone) from adrenal glands, increase calcium in cardiac muscle, and cause cardiac arrhythmia, which is associated with SDS. Taking the time to raise chickens in a stress-free environment is the best way to ensure best practice management in poultry production.

  1. Nutritional factors

Various dietary factors such as diet texture and composition can affect the incidence of SDS. Some studies indicated a higher incidence of SDS in birds fed a pellet diet rather than a mash diet. This might be related to the effect of the pellet diet on growth rate. Feeding frequency and feed intake rate can also influence the SDS condition. Although some studies have suggested feed restriction programs to slow down the growth rate and consequently incidence of SDS, this approach might not be the solution. In a study, broilers were restricted to an 8-hour feeding time per day as a feed restriction method to control the SDS. Interestingly, the feed restriction increased the feed intake rate by 9 grams per hour and the birds showed frenzied activity around the feeders. These “feed-restricted” birds showed a higher incidence of SDS compared to the control group, who had 24 hours of access to the feed. 

Reducing dietary protein levels during the SDS might decrease mortality by reducing the growth rate. Using animal-source protein ingredients such as fish meal and meat meal has decreased the incidence of SDS in some studies. This effect has been attributed to the presence of a non-essential amino acid called taurine. Although avian species are assumed to synthesize taurine, reduced cardiac taurine levels are associated with heart tissue degeneration in turkeys. Using animal protein sources might provide some protection against the SDS.

Various dietary energy sources might also influence the occurrence of SDS. A higher incidence of SDS in broiler chicks fed wheat-soybean meal-based diets than corn-soybean meal-based diets was recorded by some studies. The higher amount of biotin in corn than in wheat (0.108 mg/kg for corn and 0.043 mg/kg for wheat) may have contributed to the decreased SDS-related mortality found with a corn diet. Given that high levels of lactic acid in the crop can contribute to the SDS problem, corn-based diets are less likely to produce lactic acid than wheat-based diets. Fat is another source of energy that is used in poultry diets. Fat source and perhaps fat saturation can affect the incidence of SDS. Using unsaturated fat (e.g. sunflower oil) in broiler diets showed less SDS than feeding saturated fats such as tallow and coconut oil. Polyunsaturated fatty acids (PUFA) have been found beneficial in controlling SDS as PUFA are precursors of series 1 and 3 prostaglandins (PGs). These PGs regulate the flow of blood and transmission of nerve impulses to visceral organs. Low levels of PUFA and PGs can lead to deterioration of membrane structure, cardiac arrhythmia, heart function failure, and an increase in the incidence of SDS.

Mineral availability might affect the incidence of SDS and low availability of magnesium has been attributed to SDS. Using high levels of dietary fat, especially saturated fat, can increase the formation of soaps that are complexes of minerals such as magnesium with fatty acids. Studies with broiler breeder hens and turkeys have revealed that low dietary potassium levels can contribute to this syndrome in some cases. Potassium salts supplementation (e.g. potassium carbonate at 3.5 kg/ton) has reduced the incidence of SDS in these birds.

Vitamin nutrition has also come under close attention regarding the SDS problem. Borderline levels of biotin, pyridoxine (vitamin B6), and thiamine (vitamin B1) are associated with a high incidence of SDS. On the other hand, overfeeding of some fat-soluble vitamins such as vitamin D3 may exacerbate SDS.

Reducing the growth rate is an easy way to prevent SDS. Try to reduce lighting hours to temper the growth rate. From a nutritional aspect, avoid any increase in dietary energy and protein levels during the occurrence of SDS. Consider using a mash diet, and supplement the diet with an animal protein source, PUFA, vitamin B complex, and vitamin C under such conditions.


Proudfoot, F. G. and H. U. Hulan. 1982. Effects of reduced feeding time using all mash or crumble-pellet dietary regimens on chicken broiler performance, including the incidence of acute death syndrome. Poultry Science. 61: 750-754. link

Siddiqui, M. F., M.S. Patil, K.M. Khan, and L.A. Khan. 2009. Sudden Death Syndrome – An Overview. Veterinary World, Vol.2(11):444-447. link

Sosnówka-Czajka, E. and I. Skomorucha. 2022. Sudden death syndrome in broiler chickens: a review on the etiology and prevention of the syndrome. Annals of Animal Science. ISSN: 2300-8733. link

About the author(s)

Research Associate at Poultry Innovation Partnership | + posts

One Response

  1. Hello,

    I have observed higher SDS even with mash diets. It usually starts day 8 and quickly stops Day 18-19. I have tried different diet densities, light densities and hour of darkness, etc… to no improvements. What are your thoughts on it being due to Hypoglycemia in All veg diets?