Potassium, phosphorus & sudden death syndrome in broiler breeders

摘要

The phosphorus and potassium requirement of modern broiler breeder stock for the prevention of Sudden Death Syndrome is considerably higher than for normal productive and reproductive processes. During the period 20 to 28 weeks of age the diet should contain at least 0.65 percent potassium and 0.40 percent digestible phosphorus. Over the past 12 months a number of papers written by eminent nutritionists have reviewed the phosphorus requirement of broiler breeders. Reddy (2001) writing in Poultry International recommends 0.10 percent non-phytin phosphorus for optimum production and hatchability and a level of 02 percent or 0.30 percent for maintenance of bone minerals. In another paper Wilson recommends a non-phytin phosphorus (available phosphorus). Neither author seems to have heard of a metabolic condition known as Sudden Death Syndrome (SDS). I am not referring to the SDS which occurs in broilers but the SDS sometimes seen in adult broiler breeding stock, particularly in the so called heavy orhigh meat yielding strains which at present account for some 50 percent of the total world market for broilers. SDS was first reported back in 1978 but it was the mid 1980's before the condition was recognised in the UK. Since that time SDS has been reported in all major poultry producing countries of the world. Hopkinson (1991) published in Avian Pathology and demonstrated that potassium and phosphorus were closely linked with this condition. I have investigated in excess of 100 cases occurring in Europe, Australia, North America and Asia involving the two heavy meat yielding strains, Cobb 500 and Ross 308. SDS in female broiler breeders occurs anytime between 20 and 30 weeks of age: death is sudden! Birds are almost always well developed, well fleshed and physically in good health. At post mortem the heart is enlarged and congestion of the lungs, cloaco, ova, oviduct and liver is clearly apparent. The level of mortality may vary from 2 percent to 30 percent, the peak being at commencement of lay through age of reaching maximum feed allowance. By 30 weeks of age mortality from SDS usually ceases.