降铜对植酸酶在断奶仔猪饲粮中应用的影响

Improvement of the Effects of Phytase Application by Lowering the High Level of Copper in Piglets Diets

【目的】为了加快仔猪生长和提高饲粮消化率,仔猪饲粮中常常同时添加高剂量铜和植酸酶,但高铜对植酸酶的作用究竟有何影响却仍鲜见报道。文章研究了高铜饲粮中添加植酸酶对仔猪营养物质消化率、生产性能、粪铜和粪磷排放的影响,以及降低铜的添加量对植酸酶作用的影响。【方法】试验选取180头体重9—10 kg长×大二元杂交仔猪,随机分成3组,每组5栏,每栏12头猪,分别饲喂3种试验饲粮中的一种。试验饲粮为玉米-豆粕型饲粮,其营养水平达到或超过NRC(1998)相应阶段猪营养需要量。组1为对照组,饲粮铜添加量为180 mg·kg-1(硫酸铜),不添加植酸酶;组2和组3为植酸酶试验组,添加500 IU?kg-1植酸酶,组2和3饲粮铜添加量分别为180和120 mg?kg-1(硫酸铜)。试验预试期3 d,正试期3w,试验期间仔猪自由采食和饮水,记录采食量,观察腹泻情况,计算试验期间平均日采食量、日增重、料重比和腹泻频率。试验结束前连续3 d以栏为重复单位采集部分新鲜粪样,每100 g新鲜粪样加10 m L的10%乙醇,-20℃保存待测。以酸不溶灰分为参照内标,测定计算营养物质消化率和矿物质表观消化率。【结果】(1)高铜仔猪饲粮中添加植酸酶可使磷表观消化率提高21.12%(组2与组1相比,P<0.01),粪磷含量降低4.41%(P=0.09),腹泻频率降低19.22%(P=0.35),添加植酸酶对干物质和蛋白表观消化率,采食量、日增重和料重比均无显著影响。(2)两个植酸酶试验组相比,当铜添加量由180 mg·kg-1降低到120 mg?kg-1时,钙、磷表观消化率分别提高13.74%和9.79%(组3与组2相比,P=0.02和P=0.01),粪磷含量降低18.86%(P<0.01),腹泻频率降低25.24%(P=0.25),降铜对干物质和粗蛋白表观消化率、采食量、日增重和料重比均无显著影响。(3)与高铜无植酸酶组相比,减少铜添加量并且添加植酸酶,可使饲粮的干物质、粗蛋白、钙和磷表观消化率分别提高1.80%、2.84%、17.20%和32.98%(组3与组1相比,P=0.02,P=0.04,P<0.01和P<0.01),腹泻频率降低39.6%(P=0.04)。【结论】现有试验表明,在添加植酸酶的玉米-豆粕型饲粮中,将铜(硫酸铜形式)添加量从180 mg?kg-1减少到120 mg?kg-1可以显著减少铜对植酸酶的干扰,提高饲粮钙、磷表观消化率,降低粪铜和粪磷含量。

【Objective】 To promote the growth of piglets and nutrient digestibility, high copper and/or phytase additives are usually added to weaned piglet diets. However, the effects of high dietary copper on the phytase application are not very clear. This study was conducted to determine the effects of supplementation of phytase on nutrient apparent digestibility（AD）, growth performance, fecal copper（FCu） and fecal phosphorus（FP） in piglets with high copper diets, and the effects of reducing copper dosage on the phytase application. 【Method】 Total of 180 Landrace × Yorkshire piglets with initial body weight of 9-10 kg were randomly assigned to three dietary treatments group, 5 replicate pens of 12 piglets in each group. The diets based on corn-soybean meal meet or exceed NRC（1998） nutrient requirements. For the first group（control group, Group 1）, 180 mg·kg-1 copper from copper sulfate addition was added to the diet without phytase. For the second and third group（phytase treatment groups, Group 2 and Group 3）, 180 and 120 mg·kg-1 copper from copper sulfate addition was added to the diets with 500 IU·kg-1 phytase, respectively. Feed and water were provided ad libitum throughout the three weeks of experimental period, following by three days of adaptation. Feed consumption and diarrhea were checked daily, and body weight was recorded at the beginning and end of the experiment to calculate average daily bodyweight gain（ADG）, average daily feed intake（ADFI）, feed conversion ratio（F/G） and diarrhea frequency. At the last week, fececs were spot sampled for three consecutive days from each pen. Every 100 gram of feces was immediately added with 10 m L of 10% ethanol and stored at-20°C until required for further analysis. Nutrients apparent digestibilities were calculated using acid-insoluble ash as an index in feed and fecal samples. 【Result】 The results showed that adding phytase to high copper level diet increased phosphorus（P） apparent digestibility by 21.12%（Group 2 to Group 1, P〈0.05）, decreased FCu by 4.41%（P=0.09） and diarrhea frequency by 19.22 %（P=0.35）. No significant difference was observed in apparent digestibility of dry matter（DM） and crude protein（CP）, ADFI, ADG or F/G. Compared with two phytase treatment groups, reducing the copper supplement from 180 mg·kg-1 to 120 mg·kg-1 increased the apparent digestibility of calcium（Ca） and P by 13.74% and 9.79%（Group 3 to Group 2, P=0.02 and P=0.01）, decreased FP by 18.86%（P〈0.01） and diarrhea frequency by 25.24%（P=0.25）. No significant difference was observed in digestibility of DM, CP, ADFI, ADG or F/G. In contrast to high copper diet without phytase addition, lower copper diet with phytase addition showed higher apparent digestibility of DM, CP, Ca and P by 1.80%, 2.84%, 17.20% and 32.98%（Group 3 compare with Group 1, P=0.02, P=0.04,P〈0.01 and P〈0.01） and lower diarrhea frequency by 39.6%（P=0.04）. 【Conclusion】Results of the current experiment indicate that reducing copper supplementation in the corn-soybean meal basal diet from 180 mg·kg-1 to 120 mg·kg-1 could prevent severely diminishing phytase’s positive effects on Ca and P apparent digestibility and FCu and FP content.