EFFECT OF PHYTASE ON PROTEINS AND ELECTROLYTE UTILIZATION FOR BROILER CHICKS

Abstract

In the productive benefits of commercial microbial phytase (Ronozyme) were tested. Five experiments were run. In experiment one, four levels of phytase 0, 250, 500 and 750 FYT/U were used at 23%CP , 0.48%P and 3 Mcal/kg feed, using seventy two day-old unsexed Ross-308 broiler chicks, allotted randomly to four treatments× three replicates, each of six chicks, and experimentally fed for 42 days. Experiments 2-5 used high (0.45%) and low (0.30%) P with either high (23%) or low (19.5%) CP, all at 3 Mcal/kg feed. In xviii each experiment, thirty six unsexed Ross-308 broiler chicks were allotted randomly to two treatments× three replicates of six chicks each, and fed experimentally for 42 days. Data collected in all experiments covered performance, serum metabolites, slaughter and carcass data, tibia bone physical and chemical measurements, Ca and P balances and economical evaluations. The results indicated that diet supplementation with phytase, improved performance significantly, with the 250 FYT/U dose being higher than in the other treatment groups for body weight gain (1943.173 ±33.18), mean hot (1943.17±3.09) and cold (1924.89±3.45) carcass weights and tibia length. Total phosphorous (82.39±0.01) and total calcium (74.77 ±0.47) retentions percent and total protein (7.90±0.20) were highest in the 500 FYT/U doses. Cholesterol mean values were lower in the test groups compared to the control. Triglyceride value of the 500 FYT/U dose (124.40±4.13) was lower than the control. Meat quality subjective scores did not differ significantly inbetween groups, and scores given for all attributes are above moderate acceptability. Profitability ratios of all test groups were higher than the control group, with the 250 FYT/U dose recording the highest value (1.054). The performance values (WG, FI, FCR and energy intake) for the 750 FYT/U/kg diets were higher in test groups than the control. Test groups (the 750 FYT/U/kg diets) mean values for cholesterol and lipids were higher than the control except for serum proteins (7.34±07) in the low nP low CP% plane. Slaughter and carcass values for the 750 FYT/U/kg diets revealed that all parameters in slaughter weight, hot and cold carcasses and dressing percentages based upon them and total edible parts% to be xix higher than the control. All tibia bone measurements for the 750 FYT/U/kg diets were higher compared to the control. Total P and Ca consumptions and total P and Ca retentions% for the 750 FYT/U/kg diets were higher compared to the control except for the high nP low CP% planes where P and Ca consumptions were lower (2960.16 ±4.41 and 4905.60 ±27.9). Profitability ratios (1.065, 1.076, 1.048 and 1.012) of the test groups (750 FYT/U) were always higher than the control group. The results withdrawn were amply discussed, their practical implications were overviewed and suggestions for future researches were put forward