Effects of dietary fat source on sudden death syndrome and cardiac sarcoplasmic reticular calcium transport in broiler chickens.

Wheat and soybean diets supplemented with either tallow or sunflower oil (SFO) were fed to broiler chicks. Variables examined included performance, incidence of sudden death syndrome (SDS), and cardiac sarcoplasmic reticular (SR) calcium transport. The phospholipid content of heart tissues was also determined. Birds fed the SFO diet gained significantly (P < .05) more weight over the first 21 days of age and had a significantly better feed:gain ratio (P < .01). The incidence of SDS mortality up to 39 days of age was also lower (P < .05) for SFO-fed birds than for those fed the tallow diet. Calcium (45Ca2+) uptake and calcium-magnesium 5'-adenosinetriphosphatase (Ca2+ + Mg(2+)-ATPase) activity in cardiac SR vesicles did not differ due to diet (P > .05). However, compared with similar weight pen-mates showing no disease signs, SDS birds had depressed 45Ca2+ uptake (P < .01) and Ca2+ + Mg(2+)-ATPase (P < .05) of cardiac SR vesicles. The phosphatidylcholine concentration in the cell membranes of heart tissue of tallow-fed birds was significantly higher (P < .05) than in SFO-fed chicks. No differences were seen in other phospholipid constituents. The SDS birds, however, had significantly (P < .05) lower phosphatidylethanolamine plus phosphatidylglycerol, sphingomyelin, and total phospholipid concentrations in the heart tissues than the pen-mate controls. The results support the hypotheses that SDS in broilers is a cardiac dysfunction associated with defective cardiac SR membrane function and that dietary fat type is implicated with the syndrome.