The incidence of ascites in phytase supplemented broiler diets
A.KOWSIGAN 1, R.G.GLORIDOSS, B.S.V.REDDY, T.M.PRABHU
Department of Animal Nutrition
VeterinaryCollege, University of Agricultural Sciences
Hebbal, Bangalore - 560 024
The incidence of broiler ascites was studied in phytase supplemented isonitrogenous and isocalorific diets. With two dietary levels each of phytase enzyme (625 U/kg and 1250 U/kg), available phosphorus (0.30% and 0.40%), calcium (0.8% and 1.0%) and vitamin D 3 (2000 IU/kg and 4000 IU/kg), the 2X2X2X2 factorial designed dietary regimen resulted in a set of 16 diets of various combinations. The control diet had BIS (1992) specified level of 1.2 percent calcium (Ca) and 0.5 percent available phosphorus (Pav), and 2000 IU/ kg of vitamin D 3. The study involved seventeen treatments with two replications in each and 10-day-old chicks per replication. Mortality due to ascites was recorded only during the finisher phase (22 - 42 nd day). Nearly all the deaths during this phase were due to ascites. Mortality was not more than 10 percent in any of the treatment replications towards the end of the starter phase. Ascites was observed only in birds fed on low Pav (0.30%) diets. All the low Pav (0.30%) + high Ca (1.0%) treatments registered less than 100% livability, irrespective of the levels of vitamin D 3 and phytase. Among the low Pav (0.30%) + low Ca (0.80%) groups, irrespective of the phytase level, those fed on the higher level of vitamin D 3 (4000 IU/kg) registered 100 percent livability. The incidence of ascites was highest in diets with low Pav (0.30%) combined with high dietary calcium (1.0%). Widely placed legs, ‘water belly', cyanotic appearance, narrow rib cage and panting characterized ascitic birds. Beyond 3 weeks of age, leg weakness might have precipitated in poor feed consumption, progressive inanition, ascites and death.