| The study was conducted to investigate the effects of different levels of dietary non-phytate phosphorous(NPP) and adding phytase on growth performance, mortality, slaughter performance, body measurements, femoral development, tibia quality, toe character, internal organ development and apparent metabolic rate of nutrient in feather-frizzled broilers, then to choose the sensitive indices of reflecting the condition of phosphorous(P) nutrition of feather-frizzled broilers aged from 1 to 21 days and estimating the requirement of NPP in diet by using statistic software SAS to fit broken-line models and to evaluate the application effects of the phytase, as to estimate suitable supplementation level in this phase. A total of 480 1-day-old, healthy and homogeneous feather-frizzled broilers were randomly assigned to 8 treatments for 6 replicates of 10 birds each. The NPP level of the corn-soybean basal diet was 0.13%. By changing the content of calcium hydrophosphate, calcium carbonate and sand in the diet, treatment 1 to 6 contained 0.13%, 0.23%, 0.33%, 0.43%, 0.53% and 0.63% of NPP, respectively, and other nutrient levels were the same(calcium 1.02%). Based on treatment 3, treatment 7 and 8 were added 600 U/kg and 1 200 U/kg of phytase, respectively. The feeding experiment lasted for 21 days. The metabolism test lasted for 3 days after the feeding experiment. The results showed as follows:(1) Dietary NPP level had no significant influence on breast muscle ratio(BMR), leg muscle ratio(LMR) and abdominal fat ratio(AFR) of feather-frizzled broilers, but had significant influence on average daily gain(ADG), average daily feed intake(ADFI), feed to gain ratio(F/G), mortality, carcass ratio(CR) and eviscerated ratio(ER)(P<0.05). ADG, ADFI, F/G and ER showed the significant linear and quadratic effects(P<0.05) with the increasing of NPP level. When the NPP level was 0.13%, it had higher mortality, and reached 13.3%, which was significantly higher than other treatments(P<0.05). The mortality of other treatments were all less than 1.7%, and non-significant between them(P>0.05). Dietary added phytase had no significant influence on ADG, ADFI and mortality and various indexes of slaughter performance(P>0.05), but had significant influence on F/G(P<0.05), and no significant difference between this two groups(P>0.05).(2) Dietary NPP level had significant influence on all indexes of body measurements and femoral development(P<0.05), and among the rest of them, body length, shank length, chest width, chest depth, metatarsus length, femoral strength, femoral fresh weight, femoral length and femoral width showed the significant linear and quadratic effects with the increasing of NPP level(P<0.05), whereas width to length ratio of femoral only showed the significant linear effect. Dietary added phytase had no significantly influence on all indexes of body measurements and femoral development(P>0.05).(3) Dietary NPP level had no significant influence on calcium(Ca) content in tibia ash, ratio of Ca to P in tibia ash, Ca content in toe ash and ratio of Ca to P in toe ash of feather-frizzled broilers(P>0.05), but had significant influence on tibia strength, tibia length, dry weight of defatted tibia, tibia ash content, P content in tibia ash, dry weight of defatted toe, toe ash weight, toe ash content and P content in toe ash(P<0.05), which showed the significant linear and quadratic effects(P<0.05) with the increasing of NPP level. Dietary added phytase had no significant influence on all indexes of tibia quality and toe character except tibia strength, which was biggest with adding 1200 U/kg phytase in the diet(P<0.05), and no significant difference between other two groups(P>0.05).(4) Dietary NPP level had no significant influence on indices of heart, pancreas, kidney and apparent utilization rate of dry matter(DM), crude protein(CP), ether extraction(EE), calcium(Ca)(P>0.05), but had significant influence on indices of liver and intestines, as well as apparent utilization rate of crude ash and P(P<0.05); The indices of liver and intestines of the treatment with 0.13% NPP were highest, while other treatments were non-significant between each other. Too high or too low P level in diet was not beneficial to digestion and utilization of nutrients. Dietary added phytase had no significant influence on the indices of heart, liver, pancreas and kidney(P>0.05), but had significant influence on the index of intestines(P<0.05), which was biggest by adding 600 U/kg phytase in the diet(P<0.05), and no significant difference between other two groups. Dietary added phytase had no significant influence on the apparent utilization rate of each nutrients(P>0.05), but it improved the apparent utilization rate of Ca and P according to the data(P>0.05).In conclusion, ADG, ADFI, F/G, ER, body length, shank length, chest width, chest depth, metatarsus length, femoral strength, femoral fresh weight, femoral length, femoral width, tibia strength, tibia length, dry weight of defatted tibia, tibia ash content, phosphorus content in tibia ash, dry weight of defatted toe, toe ash weight, toe ash content and phosphorus content in toe ash were suitable for evaluating NPP requirement in diet for feather-frizzled broilers aged from 1 to 21 days. According to the above sensitive indices, the NPP requirement for feather-frizzled broilers aged from 1 to 21 days fed a corn-soybean meal basal diet were obtained from 0.23% to 0.39% by fitting broken-line models. The requirement of NPP is suggested to be 0.39%. Dietary added phytase could improve the growth performance, tibia strength, intestines development and phosphorus apparent utilization rate to some extent. Thinking about the cost and the action effects of phytase, the appropriate supplementation level of phytase for feather-frizzled broilers from 1 to 21 days old fed a corn-soybean meal basal diet(NPP 0.33%) is suggested to be 600 U/kg. |
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