Evidence for absorption of silicon and aluminum by hens fed sodium zeolite A

The mechanism of action of zeolite A (ZA) on eggshell quality could be related either to its ion-exchange properties or to individual ZA elements (Al or Si). Two experiments were conducted to determine 1) whether any ZA passes through the digestive system in its original form; and 2) whether any Al and Si absorption occurs. In Experiment 1, unfed hens were intubated with either 0 or 5 g ZA at oviposition. In Experiment 2, fed and unfed hens were intubated at oviposition with 0, 1, or 2 g ZA. At the subsequent oviposition, liver and kidney tissues, excreta, urine, bile, and plasma were collected and analyzed for Al, Si, Na, K, and P. The results indicated that approximately 7% of the intubated ZA passed through the digestive system in its original form (Experiment 1). As the intubated level of ZA increased, excreta Al and Si (P < .0001), urine Si (P < .005), and urine Al (P < .07) also increased (Experiment 2). Aluminum recovery from excreta ranged from 75 to 93% of the quantity intubated in all treatments. Corresponding values of Si from excreta of unfed and fed hens ranged from 76 to 81% and 58 to 60%, respectively. The P content of excreta was not influenced by ZA. However, excreta P was greater (P < .0001) in unfed than in fed hens. Neither plasma electrolytes (Na, K, and P) nor Al or Si levels in either liver or kidney were influenced by ZA.(ABSTRACT TRUNCATED AT 250 WORDS)