Introduction

SDS has been recognized for over 30 years, and is also referred to as acute death syndrome or “flip-overs”. It is most common in males when their growth rate is maximized. Mortality may start as early as 3-4 days, but most often peaks at around 3-4 weeks of age, with affected birds being found dead on their back. Mortality may be found at 1.5 to 2.0% in mixed-sex flocks and as high as 4% in male flocks only (George Qiao 2007) Ph.D. Poultry Nutritionist www.championfeeds.com).Sudden death syndrome has developed into a major problem to the broiler industry in many parts of the world. Broilers of all ages are affected starting as early as 2 days of age and continuing through to market age. Peak mortality usually occurs between 3 and 4 weeks of age. (Gardiner et al.,1988). The syndrome has been reported to cause between 1.31 and 2.46per cent mortality with males more commonly affected than females (Riddell and Orr, 1980), however proud foot and Hulan (1982) reported 0.90 to 3.61 per cent mortality due to SDS in broilers. From 0.71 to 4.07 per cent as reported by Riddel and Springer, (1985) where as Ononiwu et al., (1979) reported 1.0 per cent mortality due to SDS is broilers. Brigden and Riddell (1975) reported that 70- 80 per cent of male mortality and 20-25 per cent of female broilers chickens mortality could be attributed to acute death syndrome or “Flip-Over Disease”. Thus, SDS is a leading contributor to mortality in broiler chicken production. Although the precipitating event has yet to be ascertained,” Cardiovascular failure” appears to be the immediate cause of death (Siddiqui,et al., November 2009).

Background of outbreak of Sudden Death Syndrome in Kathmandu Valley

From the first week of July to October 2010 there was a sudden increase in mortality of broilers above 6 week age (Table 1) in Kathmandu valley. There were no premonitory signs. Just before death, birds appear normal and it is common to observe the birds use to eat, drink or walk normally. Then birds use to exhibit clinical signs such as extending their neck, squawk and start wing beating as well as leg extension before falling on their back.

Table 1:  Epidemiology of Affected flock with sudden Death Syndrome in July-October2010.

Postmortem finding of SDS birds:

Gross abnormalities recorded on post mortem examinations were muscle oedema, pulmonary, renal and liver congestion, dark black to pale yellow streaked liver bile filled gall bladder and congestive splenomegaly, blood clot in atrium haemorrhage in duodenal muscle , whitish yellow pasty  fluid in proventriculus gland, greenish coloration marked intact feed particles in gizzard and swollen intestine with excessive mucous filled.All these post mortem observations conform to the descriptions of the syndrome made by Ononiwu et al., (1979).

Laboratory finding of Mycobiota and Microbiota of Postmortem tissue samples.

A total 176 tissue samples of lung, liver, spleen, proventriculus and gizzard, were collected during postmortem examination and were subjected for both bacterial and mycological culture. Results of microbiological examination are given in Table 2.

Table 2:

 Rapid test for AI, ND, IBD

Treatment and Preventive measure given to the rest of birds in flock:

All birds remaining in flocks were subjected to restricted feed up to 8-10% these percentages differ from the ones in the abstract, and fed  twice daily . Supplementation with glucose containing electrolyte, liquid toxin binders, immunomodulator, and simple broad-spectrum antibiotics and acidifiers were provided in water. Vitamin B complex supplementation was totally withdrawn. All birds remaining in all affected farms responded well to the above management and there was a marked improvement in the overall condition of the flock.

Results/Discussion

Sudden Death Syndrome (SDS) is an acute heart failure disease that affects mainly fast growing male chickens that seem to be in good condition. Although a common feature in fast growing birds, the pathogenesis remains unclear (Ononiwu et. al. 1979). Cardiac arrhythmias are involved in the pathogenesis of SDS with ventricular arrhythmias (VA) being the most common observation representing premature ventricular contractions and fibrillation (Olkowski and Classen, 1997; 1998). It has been reported that broilers fed with high vitamin D3 diet above the recommended levels in an attempt to prevent commonly occurring leg problems were 2.5 fold more likely to succumb to acute heart failure and die of SDS (Nain et al. 2007). SDS was also experimentally induced by feeding diets containing the mycotoxin moniliformin that resulted into cardiac injury with subsequent alterations in cardiac electrical conductance (Reams et al., 1997) suggesting the possible role of chronic mycotoxicosis to the causation of SDS. Other implicated causes of SDS include continuous artificial lighting (Ononiwu et al., 1979b), deviations in dietary calcium and phosphorus (Scheideler et al, 1995),  feeding crumble-pellet diets (Proudfoot et al, 1982), dietary fat content (Rotter et al, 1985) and feeding frequency (Bowes et al, 1988). The latter recommendation of restricted feeding supports well the previous observation that abdominal fat deposition increases the risk of SDS such that restrictions on calorie:protein ratio decreases the incidence of SDS (Mollison et al., 1984).

Recomendation

The present investigation indicates that broilers in good body weight condition when not harvested timely and remaining in poultry shades for prolonged periods suffer stressful events and even die sudden. Also, it is possible that increased humidity and hot seasons favors the growth of mold and fungus in stored feeds increasing the risk of birds to mycotoxicosis.Detail Histopathological examination of affected organ need to be carried out for further verification of the involvement of mycotoxin for this syndrome.

References

1. Bowes VA, R.J. Julian, S. Leeson and T. Stirtzinger (1988). Effect of feed restriction on feed efficiency and incidence of sudden death syndrome in broiler chickens. Poultry Science 67(7):1102-4
2. George Qiao: Reduction of Early Mortality in Broiler Chickens through Nutrition and Management: Champion Feed service limited: www.championfeeds.com pdf  pp 1-2 2007
3. Mollison B., W. Guenter,and B.R. Boycott (1984). Abdominal fat deposition and sudden death syndrome in broilers: the effects of restricted intake, early life caloric (fat) restriction, and calorie: protein ratio. Poultry Science 63(6):1190-200
4. Nain S, B. Laarveld B, C. Wojnarowicz C, and A.A. Olkowski (2007). Excessive dietary vitamin D supplementation as a risk factor for sudden death syndrome in fast growing commercial broilers. Comparative biochemistry and physiology. Part A, Molecular & Integrative Physiology 148(4):828-33
5. Olkowski, A.A., C. Wojnarowicz, S. Nain, B. Ling, J. M. Alcorn, and B. Laarveld (2008). A study on pathogenesis of sudden death syndrome in broiler chickens. Research in Veterinary Science 85(1):131-40
6. Ononiwu, J.C., R.G. Thomson, H.C. Carlson, and R.J. Julian. (1979). Pathological Studies of “Sudden Death Syndrome” in Broiler Chickens. Canadian Veterinary Journal 20(3): 70–73
7. Ononiwu, J.C., R.G. Thomson, H.C. Carlson, and R.J. Julian. (1979b). Studies on effect of lighting on “Sudden death syndrome” in broiler chickens. . Canadian Veterinary Journal 20(3):74-7
8. Olkowski A.A. and H.L. Classen (1998). High incidence of cardiac arrhythmias in broiler chickens. Zentralblatt für Veterinärmedizin. Reihe A 45(2):83-91
9. Olkowski A.A. and H.L. Classen (1997). Malignant ventricular dysrhythmia in broiler chickens dying of sudden death syndrome. Veterinary Record. 15;140(7):177-9
10. Proudfoot FG, H.W. Hulan, K.B. McRae (1982). The effect of crumbled and pelleted feed on the incidence of sudden death syndrome among male chicken broilers. Poultry Science 61(8):1766-8
11. Reams R.Y, H.L. Thacker, D.D. Harrington, M.N. Novilla, G.E. Rottinghaus, G.A. Bennett , and J. Horn (1997). A sudden death syndrome induced in poults and chicks fed diets containing Fusarium fujikuroi with known concentrations of moniliformin. Avian Disease 41(1):20-35
12. Rotter B, W. Guenter, and B.R. Boycott (1985). Sudden death syndrome in broilers: dietary fat supplementation and its effect on tissue composition. Poultry Science 64(6):1128-36.
13. Scheideler SE, D.V. Rives, J.D. Garlich, and P.R. Ferket (1995). Dietary calcium and phosphorus effects on broiler performance and the incidence of sudden death syndrome mortality. Poultry Science 74(12):2011-8
14. Siddiqui, M. F. M. F.*, M.S. Patil, K.M.Khan, and L.A.Khan : Sudden Death Syndrome – An Overview: Veterinary World, Vol.2(11):444-447: November 2009