| It is a very popular trend that Phytase is applied in feed industry recently, but the heat-stable Phytase is among tentative phase. The problems include that the Phytase which is produced with heat stable fungus could retain how much live ability after high-temperature pelleting, the optimal amount of the Phytase in commercial feed, and whether the Phytase and the Acidifier has interaction when applied together or not. All of the problems should be researched in feed practice. Accordingly, our experiments were designed for study the effects of Heat Stable Phytase different applied dose on AA broiler growth performance, tibia quality, organ development and health status etc.Experiment 1; the effect of difference additional does of Heat Stable Phytase in broiler diet.Experiment design was followed single factor grouping method. 480 AA broilers in 1-day-old age, without distinction of male and female, were randomly divided into 5 treatment groups with 8 repeats in each treatment and 12 broilers in each repeat. Two steps feeding policy was applied. Corn-soybean based diet as basic feed.0.45% non-phytase phosphorus group as positive control and 0.25% non-phytase phosphorus group as negative control for 0-21-day-old group; 0.35% non-phytase phosphorus group as positive control and 0.18% non-phytase phosphorus group as negative control for 22-42-day-old group, contain 0.90% calcium in all. Three different dose of Phytase (400 U/kg, 500 U/kg and 600 U/kg) were added in negative control groups as test group and effects were compared.Results shown, when broilers were in age of 21-days, body weight and average daily gain were increased in all three different dose of Phytase treatment groups and the maximum body weight was found in 400 U/kg treatment group, however, there was no significant difference between test group and negative control group. When broilers were in age of 42-days, body weight and average daily gain were significantly increased in Phytase treatment groups (P<0.01), and no significant difference were found between each treatment groups, 500 U/kg group had best result. There was no significant improvement for broilers average daily feed intake with application of Phytase before age of day 21, however, average daily feed intake was significantly increased in day 35 and 42 with Phytase addition (P<0.01), 500 U/kg group were the highest. Feed meat ratio were shown a trend of improvement in the whole process, but was not significant. All weight related outcomes in test groups were not exceeded positive control groups.Application of Heat Stable Phytase improved shinbone weight and length in age of day 21, but no statistically significant difference, however in age of day 42, shinbone weight and length were significantly increased (P<0.05) by addition of Phytase, and 400 U/kg was the best. There was no significant difference between each test group. Bone phosphorus content was significantly increased (P<0.01) in Phytase group and the rate increased with increasing level of Phytase. Phytase application also increased calcium content and Ash content, however, was not significant.For organ measurements, heart weight and beating rates were not significantly differed between each group; however, addition of Phytase significantly increased liver weight (P=0.164), intestine weight (P=0.05) and intestine length (P=0.135), liver weight and intestine weight were the best in group 600 U/kg, intestine length was the best in 500 U/kg.Addition of Phytase significantly decreased broiler's leg disease and mortality rate, and rates were declined with increasing of phytase level.Experiment 2, comparative study of two kind of Heat Stable Phytase in phosphorus absence broiler dietExperimental design is similar as the first experiment, except the addition of 500 U/kgPA(T3), 500 U/kgPB(T4) and 500 U/kgPB+DA acidifier(T5) in each test group. The results shown, 42-day-old body weight and average daily gain were all significantly increased (P<0.01) in groups T3, T4 and T5; body weight in PB group was maximum, average daily gain in PB+DA was maximum. Body weight and daily increasing body mass has improved in 21-day-old broiler without significant difference. Average daily feed intake was increased in T3, T4 and T5 test group by 11.29%, 22.77% and 17.97% respectively. Feed meat ratio was decreased in each test group, with no significant difference (P=0.159).Shinbone calcium content, total phosphorus content and Ash was significantly differed in group T3, T4 and T5. Shinbone length, weight, diameter and strength were the best in the group T5 at age day-21; shinbone length and strength were the best in the group T4.Heart beating rate was significantly decreased in the group T3 at age day-21 (P=0.106) and in the group T5 at age day-42 (P=0.239). Intestine length and weight both were the best in the group T4. Liver, heart and whole intestine weight and heart beating rate were no significant difference between each test groups and no apparent regulation could follow.Leg disease and mortality rate were lowest in the group T5, which was containing both Phytase and acidifier. Leg disease and mortality rate of group T4 were decreased 24.94% and 22.96% respectively, compared to group T4 which contains only Phytase.Synthetically, it has a dramatic effect as improving performance and development of tibia and viscus when the Heat Stable Phytase is applied 400 U/kg, 500 U/kg, 600 U/kg in low level phosphorus diet for broilers while the different dose has no significant distinctness. But it might decrease performance and the quality of tibia when 0.2% effective phosphorus substituted with HSP using 400-600 U/kg in soybean meal-corn diet for broilers, and there is a certain tendency that it could help elaborating action for HSP after adding Acidifier in diet. |
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