Supplement of phytase in broiler diets 1. Diet containing rapeseed meal or sunflower meal or low protein and phosphorous levels
1997
Boonlom Cheva-Isarakul | Suchon Tangtaweewipat | Rungnapa Limchareonporn | Surapee Tonglom (Chiang Mai Univ., Chiang Mai (Thailand). Faculty of Agriculture. Dept. of Animal Science)
Phytase at 600 g/ton or 3,000 FTU/kg feed and NSP enzymes at 100 g/ton feed were either supplemented or unsupplemented to broiler diets fed during 2-7 weeks of birds' age. Rape seed meal was substituted to soybean meal (SBM) at 0, 50 and 75 percent throughout the experiment (Exp. 1). All diets were iso-caloric and iso-nitrogenous. The content of available P (aP) and Ca of all diets was adjusted to the levels recommended by NRC (1994). In Exp.2, SFM was substituted for SBM at 0, 50 and 100 percent. The diets were either unsupplemented or supplemented with 120 g/ton or 600 FTU/kg of phytase and 100 g/ton of NSP enzyme. In Exp.3, phytase enzyme at 600 FTU/kg feed was either supplemented or unsupplemented to the diet containing either normal or subnormal level of CP and/or aP. In the subnormal CP diets, 1.5 percent CP was reduced during 4-7 weeks of birds age, while the subnormal aP diets contained aP only 50-55 percent of the control. The result revealed that BW gain and feed intake significantly decreased with the increased level of RSM while FCR was not affected. It indicated that RSM could be substituted for SBM less than 50 percent. SFM could substitute for SBM at least 50 percent without adverse effect on BW gain but significantly increased FCR. The supplement of phytase and NSP enzyme did not alter the performances of broilers fed either with RSM or SFM or the control diet. The incorporation of phytase at 5 times of the recommended level (3,000 vs 600 FTU/kg feed) had no harmful effect on broilers' performances. However when phytase was supplemented to the subnormal levels of aP particularly when CP level was also low, there was significant improvement on BW gain while feed intake and FCR also tended to be improved. It could be concluded that phytase enzyme can liberate P and/or CP which have been partially bound by phytic acid. The positive effects of phytase enzyme supplement is more obvious in the subnormal level of aP than the normal level of nutrients. Therefore, phytase could be recommended for partially substitute of aP and CP at about 50 percent and 8 percent respectively.
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