Effects of Non-Phytate Phosphorus Levels and Phytase Supplement in Diet on Growth Performance and Bone Characters of Broilers

• Main Authors: Po-Chang Kuan, 管波昌
• Other Authors: B. Yu
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/93710513110664483239

碩士 === 國立中興大學 === 畜產學系 === 88 === The purpose of this experiment was to study the effect of phytase supplement in diets with different levels of non-phytate phosphorus (NPP) on growth performance and bone characters of broilers . By using corn-soybean meal as the basal diet in a 4x2 factorial treatment, the experiment was separated into two sets of trials. Trial 1 involved four levels of NPP (0.15%, 0.25%, 0.35%, 0.45%) with or without phytase (300 U/kg); as for trial 2, it involved four levels of NPP (0.25%, 0.30%, .0.35%, 0.40%) with or without phytase (300 U/kg). Trial 1 and trial 2 respectively divided 704 and 800 Arbor Acres broilers randomly into 32 pens of eight dietary treatments for a six-week feeding trial. For performance trial, the results indicated that both different NPP levels and the phytase supplement had significant effects on weight gain and feed intake during growing and finishing periods (P<0.05), and there were significant interaction between these two factors (P<0.05). Phytase supplementation did not affect on weight gain and feed intake while NPP level above 0.30%. However, adding 300 U/kg of phytase into the diet, significantly improved the weight gain and feed intake of 0.25% NPP group; moreover, this treatment had similar result with the 0.30% NPP group without phytase. As the consequence, diet with 0.30% NPP would be sufficient for the growing performance of broilers during growing and finishing periods; adding phytase (300 U/kg) into the diet reduced the NPP level from 0.30% to 0.25% without affecting the growing performance of broilers. Considering bone character, the NPP levels and phytase supplement significantly affected the tibia length, weight, ash content and phosphorus content in ash of broilers during growing and finishing periods. As for the effect on calcium in ash, the results of two trials were not identical. The tibia strength was not affected by the two factors. During growing period, the tibia length, weight, and phosphorus content in ash of broilers increased with the increasing level of NPP under 0.35% without phytase supplementation, and significantly improved by phytase supplement under 0.30% NPP. Phytase supplementation had a significant effect on phosphorus content in ash of all levels. The result of the tibia ash content were not identical in two trial: in trial one, the tibia ash content increased significantly as the NPP levels (under 0.45%) increased and phytase added (when NPP levels were under 0.35%), but this effect only appeared while NPP levels were under 0.30% and 0.25% in trial 2. As a result of tibia length, weight, phosphorus content in ash, diet with 0.35% NPP would be sufficient to provide the bone growth of broilers; the result of tibia ash content implied that 0.45% NPP in trial one and 0.30% NPP in trial two would provide the best result. However, the treatment of 0.30% NPP with phytase would satisfy all aspects of bone growth of broilers. During finishing period, the result of tibia length, weight, ash content, and phosphorus content indicated that diets with 0.30% NPP or 0.35% NPP (from ash content) would satisfy the bone growth of broilers. However, 0.25% NPP with phytase would show the same result as 0.30% NPP without phytase on tibia character. As for blood character, plasma phosphorus (plasma-P) increased as NPP levels increased (P<0.05). Phytase supplement significantly increased plasma-P (P<0.05), which lead to no significant difference was found between 0.30% NPP group and other treatments with higher levels of NPP during the growing period, and so did 0.25% during the finishing period. Plasma calcium (plasma-Ca) increased significantly with increasing NPP levels during the growing period and the finishing period while NPP levels under 0.30%. Phytase supplement decreased the plasma-Ca concentration significantly. Plasma alkaline phosphatase (ALP) activity was lower in finishing period comparing with growing period. Adding phytase also resulted in lower plasma ALP activity, but not significant. Expert the trial two during growing period, all other treatments showed that the activity decreased while the NPP levels increased. From the result of plasma-Ca and P, the NPP requirements of broilers during growing and finishing periods were respectively 0.35 - 0.40% and 0.30. By adding phytase into the diets, the NPP value decreased to 0.30% and 0.25% respectively. From the result described above, both the NPP levels and phytase supplement affected the growth. It indicated that 0.30% NPP provided sufficient requirement for broilers during the growing and finishing period. Phytase supplement reduced the NPP level from 0.30% to 0.25% without affecting the growth performance. The result of bone character indicated that 0.30 - 0.45% NPP levels were sufficient for growing and finishing period broilers, respectively. Phytase supplement reduced the NPP level to 0.30% and 0.25%, respectively. The result of blood character indicated that 0.35 - 0.40% and 0.30% NPP were sufficient for broilers respectively during growing and finishing period. And phytase supplement reduced the NPP level to 0.30% and 0.25%, respectively.