NUTRITION ▶▶▶
Controlling Sudden Death Syndrome via feed strategies
BY SALAH ESMAIL S
udden Death Syndrome occurs in broiler chickens of all ages and at the onset of sexual maturity in broiler breeders. Affected birds unexpectedly jump in the air, convulse, squawk, flip over and die. Mortality due
to SDS ranges from 0.5% to 9.62% in broiler chickens and from 0.5% to 3.0% in broiler breeders. Economically, SDS is a major source of instant profit loss. According to US statistics, preventing SDS would result in an estimated saving of US$ 130-265 million. The control of SDS, therefore, is consid- ered of paramount importance in alleviating the problem. Feeding strategies and other management strategies can help to achieve this.
Feed ingredients A greater incidence of SDS has been recorded in broiler chicks fed with wheat-soybean meal diets than corn-soybean meal- based diets. The increased amount of biotin provided by corn relative to the amount provided by wheat (0.108 mg/kg for corn and 0.043 mg/kg for wheat) may have contributed to the decreased mortality found with a corn diet. There is also a marked increase in lactic acid in the crop when a high protein diet containing an excess of sulphur is fed to the birds in combination with most grain feeds. With corn-based diets, however, the problem is less severe due to the lower levels of lactic acid. A study conducted on 51 broiler flocks in Canada reported that the SDS incidence was greater in flocks fed a diet supplied by a feed company that uses less corn and more of other grain types.
Protein A lower incidence of SDS (50%) was recorded in 29-56 day- old broiler chickens fed with a 24% protein finisher diet, rela- tive to birds fed a 19% protein finisher diet. The incidence of SDS also appeared to decrease when a meat meal was used in the diet. It was concluded that meat meal sources provided one or more unknown factors which protected birds against SDS. Further, diets including meat meal contain less salts and
Sudden Death Syndrome (SDS) is a problem that has been observed in many countries where other major poultry diseases have been brought under control. Smart feeding strategies can limit SDS incidence and damage.
supplemental fat which can have a considerable impact on the incidence of SDS.
Lipids It was found that birds fed with saturated oils, such as sun- flower oil, had the lowest incidence of SDS and also showed lower mortality from SDS than broilers fed with a saturated fat source, such as tallow. The levels of linoleic and arachidon- ic acids are lower when sunflower oil is used and increase when tallow is used as a fat supplement. These acids act as precursors to prostaglandins (PGs), a family of lipid-like com- pounds derived from polyunsaturated fatty acids. A higher level of PGs may be involved in the development of SDS by inducing a sequential pathological process that causes hypoxia, enhances respiratory distress and leads to SDS.
Minerals Using diets containing lower levels of calcium, phosphorus, potassium and magnesium, the incidence of SDS was suc- cessfully reduced and the supply of these elements therefore should be taken into account. This particularly applies when the diet contains high levels of saturated fatty acids. With such diets, an insoluble soap is formed in the digestive tract which decreases the retention of these minerals. This reaction can influence the nervous system and in turn create the necessary conditions for SDS to occur.
Vitamins It has been suggested that vitamin K, which is an anti-hemor- rhagic vitamin, might also be involved in SDS, since extensive hemorrhaging of the kidneys and blood clots were often found in SDS broilers. In one study three different levels of
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