Complex study of the physiological role of aluminium. II. Aluminium tolerance tests in broiler chickens

Aluminium (Al) tolerance tests were carried out in 8 x 24 (a total of 192) broiler chickens pre-reared for 17 days. Chickens of the control group were fed a standard poultry grower diet ad libitum, while those in six experimental groups received a diet supplemented with different (200, 500 and 1,000 mg/kg of feed) doses of Al supplied in the form of AlCl3 and, in two cases, with the same dose of P added to the feed in the form of MCP, up to 52 days of age. Chickens of one group were fed a diet containing 3,000 mg Al per kg of feed for 70 days. The acidic pH of AlCl3 solution sprayed onto the feed was neutralized by adding a sufficient amount of NaHCO3 solution in all but one group. The birds' health status was monitored regularly throughout the feeding trial. Their body mass gain and feed consumption were recorded weekly. At the end of the trial, 3-10 chickens per group (a total of 40 birds) were exsanguinated, subjected to gross pathological examination, and samples were taken from 9 organs (liver, kidney, skeletal muscle, myocardium, brain, spleen, testicle, lungs and tubular bones) for light and electron microscopic examination and for the regular determination of 8 elements (Ca, P, Mg, Zn, Fe, Mn, Cu, Al). In addition, samples were taken from the organs of 2-5 chickens per group for analysis for additional 6 elements (Mo, Co, Ni, Sr, Na, K). From the results obtained the following main conclusions were drawn: (i) With the exception of four birds culled during the trial, all chickens remained symptomless throughout, and all chickens except those fed a diet supplemented with 3,000 mg/kg aluminium developed properly. (ii) The body mass of chickens in groups fed a diet supplemented exclusively with Al decreased moderately (by 67, 69 and 88 g, respectively), depending on Al concentration of the diet. Chickens fed a diet containing 3,000 mg/kg Al showed a very substantial (621.3 g; 32%) decrease in body mass Phosphorus supplementation did not markedly affect the body mass gain. (iii) Specific feed utilization was satisfactory (2.100-2.210 g/kg body mass). The very poor feed utilization of chickens subjected to the heaviest Al load can be attributed to the temporary disturbance of acid-base balance caused by the non-buffered AlCl3 solution.