生长猪植酸酶的磷当量研究

Study on Phosphorus Equivalent of Phytase in Growing Pigs

本文旨在研究饲粮中添加植酸酶对植酸磷利用的影响,确定生长猪的植酸酶磷当量。本试验采用单因素试验设计,以NaH2PO4.2H2O提供外源无机磷,同时添加植酸酶,设计1个低磷基础日粮、4个加磷日粮和3个加酶日粮,分别提供0.4、0.8、1.2、1.6g/kg的有效磷或500、750、1000FTU/kg植酸酶。选择96头体重22kg左右的杜长大三元杂交猪,随机等分到8个处理中。通过回归分析,建立响应指标(猪趾骨折断强度和趾骨灰分磷含量)与外源磷添加量之间的线性关系,进而确定植酸酶的磷当量值。结果表明:(1)随外源磷和植酸酶水平的提高,试验猪生产性能明显改善(P<0.05),趾骨灰分磷含量和血磷水平都极显著地升高(P<0.01);(2)无机磷添加水平与响应指标之间存在较强线性关系:y=10.79x+27.23(x-添加磷(g/kg),y-趾骨强度(kg),R2=0.92);y=1.44x+6.86(x-添加磷(g/kg),y-灰分磷(%),R2=0.99);(3)植酸酶的磷当量值与日粮中植酸酶和无机磷水平密切相关,同时也受相应指标种类的影响。本试验条件下,500、750、1000FTU/kg植酸酶分别可替代1kg玉米-豆粕日粮中0.09g、0.44g和0.72g(折断强度)或0.23g、0.58g、1.06g(灰分磷)无机磷。

To determine the efficacy of P releasing from phytate and determine the phosphorus equivalent of different level phytase supplementation in corn-soybean diet for growing pigs. Single factor design was used for the trial. Taken corn-soybean as low-P （0.37% total P,0.07% available P） basal diet,four gradual monosodium phosphate （MSP） added diets （0.4, 0. 8,1.2,1.6 g/kg added P）, as well as 3 gradual phytase added diets （500,750,1 000 FTU/kg phytase）, respectively. A total of ninety-six growing pigs （Duroc × Landrace × York） weighted about 22 kg were alloted to the above 8 dietary treatment randomly,the linear relationships were established between supplemented P and response parameters to evaluate phytase phosphorus equivalent in terms of improvement of response parameter by phytase in diets. The results showed that 1） swine performance were increased significantly （P〈0.05） ;ash P and serum concentration of inorganic P were increased significantly（P〈0. 01）with increased levels of MSP and phytase;2）the gradual supplemental P and response index fitted well with linear model., y = 10. 79x ＋ 27.23 （x-added P（g/kg） ; y-metacarpal-metatarsal strength （kg）, R^2 = 0.92）or y = 1.44x ＋.6.86 （x-added P（g/kg） ;y-ash P（ % ）, R^2 =0. 99） ;3）Phosphorus equivalent of phytase was affected not only by P or phytase levels in diets, but also by response indicator. Phosphorus equivalent of phytase of growing pigs calculated from the equation is 500, 750,1 000 FTU/kg of phytase included in corn-soybean diet,inorganic P released from phytate was 0.09 g,0.44 g and 0.72 g when evaluated by bone breaking strength or 0.23 g, 0. 58 g, 1.06 g by bone ash P,respectively.