研究了将新型共有细菌6-植酸酶变体(PhyG)添加到植酸P(PP)含量高的日粮中时,对年轻肉鸡氨基酸(AA)和磷(P)的表观回肠消化率(AID)的影响。不添加无机磷酸盐(Pi)和可消化(dig)AA和代谢能(ME)。总共256只罗斯308只雄性肉鸡被分配到4种处理(8只鸟/笼,8个笼子/治疗),完全随机设计。治疗包括阳性对照(PC,2,975千卡/千克ME,3.7g/kg挖磷,2.83g/kgPP,8.4g/kgCa,10.6克/千克挖赖氨酸),阴性对照(NC),不添加Pi(ME-68kcal/kg,粗蛋白-10g/kg,挖AA-0.1至-0.4g/kg,Ca-2.0g/kg,挖P-2.2g/kg,Na-0.4g/kg与PC),和NC加上500或1,000FTU/kg的PhyG。测试日粮为玉米/大豆/菜籽粕/米糠,年龄为5至15天。在第15天收集回肠消化物和胫骨。在第12至15天期间收集排泄物以确定P保留。NC(vs.PC)降低(P<0.05)P保留(-10.4%单位),胫骨灰分(-14.3%单位),体重增加(-109克),采食量(-82克)和增加的FCR(从1.199到1.504),确认NC的营养和能量极度缺乏。植酸酶添加到NC线性(P<0.001)提高了性能,但由于NC中严重的营养/能量减少,并未将其完全恢复到PC的水平。植酸酶线性增加P保留(P<0.001),胫骨灰分(P<0.001),干物质含量(P<0.05),氮(P<0.01),总能量(P<0.05),全部17个个体AA(P<0.01)。在1,000FTU/kg时,植酸酶增加(P<0.05)与P保留PC和NC(+14.5和+24.9%单位,分别)和增加胫骨灰分与NC(+13.8%单位),相当于PC。NC降低了Cys的AID,Gly,Thr,和Metvs.PC(P<0.05)。在1,000FTU/kg时,植酸酶增加了所有17AA的AID。NC(P<0.01),相当于PC。在1,000FTU/kg时,AIDAA反应(高于NC)范围从+4.5%(Met)到+15.0%(Cys),对于必需的Thr(10.4%)和Val(8.2%)以及非必需的Cys(15.0%)和Gly(10.4%)最大。结果突出了PhyG在500至1,000FTU/kg的剂量水平下在年轻肉鸡中改善氮的回肠消化率的功效,AA,和能量以及P保留和胫骨灰分。性能数据强调需要在外源酶研究中将可消化的营养素摄入量作为响应变量。
微生物植酸酶广泛用于商业肉鸡日粮中,以改善磷(P)的消化并减少其排泄到环境中。植酸酶可改善磷和其他营养素(包括氨基酸(AA))的消化。这项研究评估了在不添加任何无机P的情况下添加到营养减少饮食中的新型共有细菌6-植酸酶变体(PhyG)对幼龄肉鸡回肠中包括P和AA在内的营养物质消化率的影响。还评估了对P保留和骨矿化的影响。与未补充的阴性对照饮食相比,PhyG提高了生长性能,P保留,骨矿化(胫骨灰分),干物质消化率,氮,总能量,以及所有17个个体AA在孵化后5至15天期间,以剂量依赖性方式(剂量范围为每公斤饲料0至1,000植酸酶单位[FTU])。对于一些AA,在1,000FTU/kg时,PhyG的消化率显着增加(半胱氨酸:15.0%,苏氨酸:+10.4%),对于所有AA,都等同于营养充足的阳性对照(未补充)饮食产生的反应。结果表明,PhyG提高AA消化率和生长性能的功效,P保留,和年轻肉鸡的骨矿化。
The effect of a novel
consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) and
phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME -68 kcal/kg, crude protein -10 g/kg, dig AA -0.1 to -0.4 g/kg, Ca -2.0 g/kg, dig P -2.2 g/kg, Na -0.4 g/kg vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on day 15. Excreta was collected during days 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (-10.4% units), tibia ash (-14.3% units), weight gain (-109 g), feed intake (-82 g) and increased FCR (from 1.199 to 1.504), confirming that the NC was extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but did not fully recover it to the level of the PC due to the severe nutrients/energy reduction in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05), and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr, and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.
Microbial phytase is widely used in commercial broiler diets to improve digestion of
phosphorus (P) and reduce its excretion into the environment. Phytase improves the digestion of
phosphorus and other nutrients including amino acids (AA). This study evaluated the effect of a novel
consensus bacterial 6-phytase variant (PhyG) added to a nutrient-reduced diet without any added inorganic P on the digestibility of nutrients including P and AA in the ileum of young broilers. Effects on P retention and bone mineralization were also assessed. Compared to an unsupplemented negative control diet, PhyG improved growth performance, P retention, bone mineralization (tibia ash), digestibility of dry matter, nitrogen, gross energy, and all 17 individual AA during 5 to 15 d post-hatch, in a dose-dependent manner (dose range 0 to 1,000 phytase units [FTU] per kilogram of feed). For some AA, the increases in digestibility with PhyG at 1,000 FTU/kg were substantial (cysteine: +15.0%, threonine:+10.4%), and for all AA were equivalent to the responses produced by a nutritionally adequate positive control (unsupplemented) diet. The results demonstrate the efficacy of PhyG to improve AA digestibility alongside growth performance, P retention, and bone mineralization in young broilers.