不同添加方式植酸酶处理豆粕对牙鲆生长和饲料利用率的影响

以初始平均体重(2.02±0.02)g的牙鲆(Paralichthys olivaceus)为实验对象,进行为期70d的摄食生长实验,研究不同添加方式的植酸酶对牙鲆生长和饲料利用的影响。在5000.0g豆粕中添加2.5g植酸酶,然后用产朊假丝酵母(Candidautilis)进行发酵预处理,得到植酸酶预处理豆粕。共制作4种等氮等能(粗蛋白49.7%、总能20.9kJ/g)饲料,对照饲料主要以鱼粉为蛋白源;在对照饲料的基础上,用豆粕蛋白替代45%的鱼粉蛋白配制成豆粕组饲料;在每千克豆粕组饲料中添加1000IU植酸酶,配制成植酸酶组饲料;用植酸酶预处理豆粕蛋白替代45%的鱼粉蛋白配制成植酸酶预处理豆粕组饲料。结果表明,与对照组相比较,用豆粕蛋白替代饲料中45%的鱼粉蛋白,若不添加植酸酶则显著降低牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05);直接添加植酸酶组、植酸酶预处理豆粕组牙鲆的特定生长率、饲料效率、蛋白质效率和氮贮积率与鱼粉对照组相比较没有出现显著差异(P0.05);与不添加植酸酶的豆粕组相比较,在含豆粕饲料中添加1000IU/kg饲料的植酸酶显著提高牙鲆的特定生长率(P0.01)、氮贮积率(P0.05)和磷贮积率(P0.01),显著降低氮排放率(P0.05)和磷排放率(P0.01),但饲料效率和蛋白质效率没有显著变化(P0.05);在豆粕中添加植酸酶进行发酵预处理,降低了豆粕中植酸含量,在饲料中添加植酸酶预处理豆粕显著提高牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05),显著降低氮(P0.05)、磷和钙的排放率(P0.01)。       

无鱼粉低磷饲料中添加中性蛋白酶和植酸酶对建鲤生长及营养物质利用的影响

在无鱼粉低磷饲料中添加中性蛋白酶、中性植酸酶, 考察对建鲤(Cyprinus carpio var. Jian)生长、营养物质消化率和沉积率、血浆生化指标及肠道组织学的影响。配制含鱼粉5%和磷酸二氢钙1.5%的正对照饲料、无鱼粉饲料、无鱼粉低磷饲料(磷酸二氢钙1.0%)和在无鱼粉饲料中添加175 mg/kg蛋白酶, 在无鱼粉低磷饲料中添加175 mg/kg蛋白酶+300 mg/kg植酸酶的5组等蛋白饲料, 饲喂初始体重为(52.5±2.0) g的建鲤10周。结果表明: 对照组具有最高增重率和最低饲料系数(P<0.05), 无鱼粉饲料和无鱼粉低磷饲料组的增重率、蛋白质和磷沉积率、蛋白质和钙消化率均显著下降(P<0.05); 在无鱼粉饲料中添加蛋白酶后, 提高了建鲤增重率13.1%(P<0.05), 达到和对照组基本一致的水平; 显著提高了蛋白质、钙消化率和肠绒毛高度, 降低了饲料系数(P<0.05); 在无鱼粉低磷饲料中添加蛋白酶和植酸酶后, 显著提高了脂肪、蛋白质、磷沉积率和蛋白质、钙、磷消化率(P<0.05), 增加了前肠绒毛长度和隐窝深度(P<0.05), 提高了血浆磷浓度(P<0.05)。以上结果表明, 在全植物性蛋白饲料中添加蛋白酶, 在全植物蛋白的低磷饲料中同时添加蛋白酶和植酸酶可以促进建鲤生长, 提高对营养物质的消化率和沉积率, 促进肠道生长发育。     

Phytase can reduce theneedfor monocalcium phosphate supplementation in soybean and rapeseed meal‐based diets of black sea bream,Acanthopagrus schlegelii (Bleeker, 1854)

A feeding trial was conducted to study the effect of partial replacement of dietary monocalcium phosphate (MCP) with phytase on growth performance, feed utilization and phosphorus discharge in black sea bream, Acanthopagrus schlegelii. In the feeding trial, the control diet (designated as P1.5) was prepared with 1.5% MCP but without phytase, and the three other diets (designated as PP1.0, PP0.5 and PP0, respectively) were supplemented with 1.0%, 0.5% and 0% MCP, respectively, along with 200 mg (400 U) phytase/kg diet in each. Each diet was tested in triplicate tanks and fish were fed twice daily to satiation. After an 8‐week feeding trial in indoor flow‐through cylindrical fibreglass tanks (25 fish per tank, initial body weight: 11.5 ± 0.12 g), fish fed with PP1.0 and PP0.5 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared to the control (p > .05), whereas fish fed with PP0 showed a significantly lower growth performance in the above parameters (p < .05). The addition of phytase did not affect the body composition or muscle composition. The apparent digestibility coefficients (ADCs) of crude protein and phosphorus increased when fish were fed diets in which MCP was replaced by phytase. Phosphorus discharge was also significantly reduced in fish fed diets in which MCP was replaced by phytase (10.2 ± 0.50 to 8.01 ± 0.47 g/kg weight gain). The present study suggests that dietary MCP can be reduced when phytase is added to the black sea bream diet, with a maximum MCP reduction level of up to 1% when phytase is supplemented at 200 mg (400 U)/kg diet. Thus, phytase in the diet of black sea bream is economically and ecologically beneficial.     

植酸酶对斑点叉尾鲴生长性能及磷当量的研究

试验旨在研究饲料中添加植酸酶对斑点叉尾 [初始平均体重(1.70±0.04) g]生长性能及植酸磷利用的影响, 确定植酸酶的磷当量。试验采用单因素试验设计, 以 Ca(H2PO4)2提供外源无机磷, 同时添加不同浓度植酸酶, 试验设计为 10 个处理组, 分别为 1 个对照试验组、4 个无机磷试验组(0.3%、0.5%、0.8%、1.2%)和 5 个植酸酶试验组(300、500、1000、1500、2000 U/kg), 每个处理 3 个重复, 每个重复 30 尾鱼。通过折线模型确定植酸酶的最佳添加量; 通过回归分析, 建立响应指标(特定生长率、椎骨磷)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)添加植酸酶的处理组与对照组相比, 增重率、特定生长率、蛋白质效率、肥满度均有显著提高(P<0.05), 饲料系数、肝体比、脏体比均有下降(P<0.05), 成活率各处理组没有显著差别(P>0.05); 鱼体粗蛋白、粗灰分、钙、磷及椎骨粗灰分、钙、磷均有显著提高(P<0.05), 鱼体粗脂肪含量有所下降。(2)无机磷添加水平与响应指标之间线性关系如下: Y1=0.2714X+2.294(X-无机磷, Y1-特定生长率, R2=0.9238), 300、500、1000、1500 和 2000 U/kg 植酸酶分别可替代 1 kg 饲料中 0.13%、0.57%、0.76%、1.46% 和 1.35% 的 磷 酸 二 氢 钙 , 等 效 于 添 加 了 0.03% 、 0.14% 、 0.19% 、 0.36% 和 0.33% 的 有 效 磷 ;Y2=0.8737X+5.1028(X-无机磷, Y2-椎骨磷, R2=0.9638), 300、500、1000、1500 和 2000 U/kg 植酸酶分别可替代1 kg 饲料中 0.47%、1.11%、1.18%、1.38%和 1.41%的磷酸二氢钙, 等效于添加了 0.12%、0.27%、0.29%、0.34%和 0.35%的有效磷。在试验条件下, 添加 1000―2000 U/kg 植酸酶能有效改善斑点叉尾 生长性能, 有利于营养物质在鱼体中的沉积, 促进骨骼矿化。以特定生长率为响应指标, 植酸酶最佳添加量为 1435 U/kg等效于添加了 0.37%的有效磷; 以椎骨磷为响应指标, 植酸酶最佳添加量为 1226 U/kg 等效于添加了 0.33%的有效磷。     

Partial replacement of monocalcium phosphate with neutral phytase in diets for grass carp,Ctenopharyngodon idellus

A 9‐week experiment was designed to study the effects of partial replacement of monocalcium phosphate (MCP) with neutral phytase on growth, body compositions, serum biochemical statuses and intestinal digestive enzyme activities of grass carp, Ctenopharyngodon idellus. The control diet (designated as P2.0) was prepared with 2.0% MCP but without phytase. The three other diets (designated as PP1.5, PP1.0 and PP0.5, respectively) were supplemented with 1.5, 1.0 and 0.5% MCP, respectively, along with 500 FTU of neutral phytase kg^?1 diet in each. After a 9‐week feeding trial, fish (initial body weight: 43.44 ± 2.37 g) fed with PP1.5 and PP1.0 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared with the control (P > 0.05) whereas fish fed with PP0.5 showed significantly lower growth performance in the above parameters. The crude lipid content in whole body or muscle of the fish fed with PP1.5 was significantly lower than the control while significantly higher in fish fed with PP0.5 (P < 0.05), whereas no obvious change was observed in the fish fed with PP1.0. For serum indices, higher serum alkaline phosphatase (Alkp), phosphorus (P) and calcium (Ca) contents were observed in fish fed with phytase‐supplemented diets in comparison with the control. In addition, dietary phytase supplementation increased amylase activity and decreased lipase activity in both foregut and hindgut. The present study suggests that dietary MCP can be reduced when neutral phytase is added to the grass carp diet, and that the maximum MCP reduction level can be up to 1% when neutral phytase is supplemented at 500 FTU kg^?1 diet.     

Sparing effect of microbial phytase on zinc supplementation in maize-soya-bean meal diets for chickens

The experiment was conducted to evaluate the sparing effect of microbial phytase on the need for dietary zinc supplementation in chicks. A maize–soya-bean meal basal diet, containing 33 mg of zinc and 16 mg of copper per kg, supplemented with 0, 6, 12, 18, 24, 30 or 60 mg of zinc as sulphate per kg or with 250, 500, 750 or 1000 units (FTU) of microbial phytase (3-phytase from Aspergillus niger, Natuphos®) per kg was given to 1-day-old chicks for 20 days. Sixteen chicks placed in individual cages were assigned to each diet except the unsupplemented basal diet which was assigned to 32 cages. Actual range of phytase supplementation was 280 to 850 FTU per kg diet. Growth performance was not affected by microbial phytase. Chicks given the unsupplemented basal diet and the basal diet supplemented with 60 mg of zinc per kg displayed similar performance. Bone weight, bone ash, liver weight and liver dry matter were independent (P > 0.1) of zinc and phytase supplementations. Plasma, bone and liver zinc concentrations increased linearly (P < 0.001) and quadratically (P < 0.001; P < 0.001 and P < 0.05, respectively) with zinc added. Plasma zinc tended to increase linearly (P = 0.07) and bone zinc increased linearly (P < 0.01) with phytase added but no quadratic response was detected (P > 0.1). Liver zinc was unresponsive to phytase added (P > 0.1). Liver copper decreased linearly (P < 0.001) and quadratically (P < 0.01) with zinc supplementation. Mathematical functions were fitted to the responses of plasma and bone zinc to zinc and phytase added and used to calculate zinc equivalency values of phytase. The models included a linear plateau response to zinc added and a linear response to phytase added. In diets without phytase, plasma and bone zinc concentrations were maximised for a dietary zinc concentration of 55 and 51 mg/kg, respectively. Over the range of 280 to 850 FTU, 100 FTU was equivalent to 1 mg of zinc as sulphate. Consequently, in a maize–soya-bean meal chicken diet formulated to contain 60 mg zinc per kg, zinc ingested, and in turn, zinc excreted may be reduced by around 10% if the diet contains 500 FTU as Natuphos® per kg.     

Effects of phytase supplementation on production performance,egg and bone quality,plasma biochemistry and mineral excretion of layers fed varying levels of phosphorus

Excessive fecal excretion of phosphorus (P) has increasingly become an environmental issue due to oversupply of P in layer rations, and thus it is imperative to minimize safety margins for P to ensure the sustainability of the egg industry. In this study, a 12-week feeding trial (22 to 34 weeks of age) was conducted to evaluate the effects of phytase supplementation on production performance, plasma biochemistry, egg and bone quality and P excretion of laying hens fed various levels of non-phytate P (NPP). Forty-eight Lohmann white laying hens were randomly allocated to one of six corn–soybean meal–oat-based diets: diets containing 2.0, 2.5 or 3.0 g/kg NPP without phytase, and diets containing 1.0, 1.5 or 2.0 g/kg NPP with phytase (1 000 U/kg diet) where phytase inclusion was expected to provide 1.0 g/kg NPP to laying hens, thus making the phytase-unsupplemented treatment served as a control for the phytase-supplemented treatment accordingly. Productive performance was recorded during the experimental period. Blood and egg samples were collected, and digestibility studies were conducted at weeks 6 and 12 of the experiment. Bone mineralization was evaluated at the end of the experiment. Egg weight and egg production, feed consumption, BW and feed conversion ratio of laying hens fed lower NPP diets supplemented with phytase were comparable to those of hens fed high NPP phytase-unsupplemented controls. Eggshell thickness, specific gravity, Haugh units, tibia bone mineral density, tibia ash percent, plasma P and other biochemical parameters were not significantly different among dietary treatments. Total P intake, excretion and retention were affected by diet (P < 0.001), but its deposition in eggs was not significantly different. Contrast analysis further showed that total P excretion of phytase present vs phytase absent was averagely reduced by 40.4 mg/hen per day (P < 0.01). Moreover, total P excretion was linearly (P < 0.01) reduced with lowering dietary NPP, and this relationship was similar regardless of whether phytase was supplemented or not. The results from this study indicated that NPP levels in laying hen diets could be reduced to 1.0 g/kg (excluding the portion of NPP released by phytase) with the inclusion of phytase, without negative effects on production performance and health of the hens, thereby diminishing P excretion into environment.     

异育银鲫幼鱼对饲料中维生素K需求的研究

以不同维生素K水平(0.13、2.15、3.25、6.40、12、17.20和23.20 mg/kg饲料)的7种精制饲料喂养初始体重约为(2.17±0.01) g的异育银鲫(Carassius auratus gibelio)10周, 每个处理3个重复, 研究异育银鲫对维生素K的需求量。结果显示: 饲料中维生素K的添加可以明显降低摄食率, 饲料中维生素K含量为2.15 mg/kg时, 摄食率出现最大值, 之后显著下降(P<0.05), 在12 mg/kg时达到最低值。特定生长率随着维生素K的添加表现出升高的趋势, 饲料中维生素K含量为12 mg/kg时, 出现最大值, 但是差异不显著(P>0.05)。饲料中维生素K的含量从0.13 mg/kg升至3.25 mg/kg时, 饲料效率显著升高(P<0.05), 随着饲料中维生素K的进一步添加, 趋于稳定(P>0.05), 在12 mg/kg时达到最大值, 并且与特定生长率呈正相关关系(SGR=0.01 FE+0.95, R²=0.95)。血液红细胞数目随着饲料维生素K含量的增加先显著升高(P<0.05), 在6.40 mg/kg时达到最大值, 之后趋于稳定(P>0.05)。血红蛋白含量、血球容积比、血清钙含量与血液中红细胞数目表现出相似的趋势, 均在不添加维生素K组出现最低值, 但是差异不显著(P>0.05)。肝体比、肥满度及鱼体生化组成均不受饲料维生素K水平的影响(P>0.05)。分别对饲料效率、红细胞数目进行折线回归得出异育银鲫幼鱼对维生素K的最适需求量为3.73—6.72 mg/kg饲料。     

Biotechnological production and applications of phytases

Phytases decompose phytate, which is the primary storage form of phosphate in plants. More than 10 years ago, the first commercial phytase product became available on the market. It offered to help farmers reduce phosphorus excretion of monogastric animals by replacing inorganic phosphates by microbial phytase in the animal diet. Phytase application can reduce phosphorus excretion by up to 50%, a feat that would contribute significantly toward environmental protection. Furthermore, phytase supplementation leads to improved availability of minerals and trace elements. In addition to its major application in animal nutrition, phytase is also used for processing of human food. Research in this field focuses on better mineral absorption and technical improvement of food processing. All commercial phytase preparations contain microbial enzymes produced by fermentation. A wide variety of phytases were discovered and characterized in the last 10 years. Initial steps to produce phytase in transgenic plants were also undertaken. A crucial role for its commercial success relates to the formulation of the enzyme solution delivered from fermentation. For liquid enzyme products, a long shelf life is achieved by the addition of stabilizing agents. More comfortable for many customers is the use of dry enzyme preparations. Different formulation technologies are used to produce enzyme powders that retain enzyme activity, are stable in application, resistant against high temperatures, dust-free, and easy to handle.     

Effect of different levels of phytase on growth and mineral deposition in common carp (Cyprinus carpio,L.)

The effect of phytase (Ronozyme P) on growth and mineral deposition in common carp (Cyprinus carpio L) was evaluated. Five diets (treatments T1‐T5) were prepared to contain about 36.6% DM proteins and 0.55% DM phosphorus. Diet 1 had no supplement; diet 2 was supplemented with 2.80 g inorganic phosphorus (P) (Na₂HPO₄) kg^?1. Diets 3, 4 and 5 were supplemented with 500, 750 and 1000 U phytase kg^?1. After 126‐day feeding trials, fish grew from 39.9 g to 158 g, 262 g, 155 g, 166 g and 172 g in diets T1‐T5, respectively. There were no differences (P > 0.05) in mean weight gain, SGR, feed intake or feed conversion ratio of fish in T1, T3, T4 and T5. T2 fish had the best (P < 0.05) growth performance. Apparent P digestibility was significantly higher in T2, while faecal P discharges were significantly reduced in T3, T4 and T5. Fish in T2, T3 and T4 had higher (P < 0.05) bone P than that in T1. Vertebral Mg (mg g^?1 DM) of fish in T3, T4 and T5 were higher (P < 0.05) than that of fish in T1. Bone Mn showed the same trend. Data indicated that the enzyme exhibited no clear improvement for a higher P availability.     

Dietary methionine requirement of pre‐adult blunt snout bream, (Megalobrama amblycephala Yih, 1955)

A nine‐week feeding trial was conducted to test the hypothesis that an adequate methionine diet might improve growth, feed utilization, body composition and physiology, and biochemical parameters in pre‐adult blunt snout bream Megalobrama amblycephala, whereas a methionine deficiency might have adverse effects on these parameters. Six isonitrogenous and isoenergetics semi‐purified diets (33.0% crude protein, 7.0% crude lipid) were formulated to contain graded methionine levels (0.39–1.54% of dry weight) at 0.25% increments replaced by equal proportions of glycine. Results show that the survival rate (SR) was not significantly affected by the dietary methionine level. Final weight (FW), feed efficiency ratios (FER), weight gain (WG), and specific growth rate (SGR) increased with increasing dietary methionine levels up to 1.00% and then showed a declining trend. Using quadratic regression analysis of FER and SGR, the dietary methionine requirement was estimated to be 0.74% (2.24% of dietary protein) and 0.76% of the diet (2.30% of dietary protein), respectively. Fish fed the 0.39% methionine diet showed significantly lower whole body protein content compared to those fed with 0.85, 1.00 and 1.24% methionine diets (P < 0.05). Whole body moisture, lipid, and ash contents in pre‐adult adult blunt snout bream were not significantly affected. The urea content in fish fed the 0.85% methionine diet was significantly higher than those of fish fed a 0.39, 0.56, 1.24, 1.54% methionine diet (P < 0.05), but not significantly different in fish fed the 1.00% methionine diet (P > 0.05). No significant differences were found in other indexes such as the hepatosomatic index (HSI), viscerosomatic index (VSI), condition factor (CF), albumin (ALB), total protein (TP), alanine aminotransferase (ALT), and spartate transaminase (AST) (P > 0.05). Most important, the optimal dietary methionine level of pre‐adult blunt snout bream should be 0.74–0.76% of the diet (2.24–2.30% of dietary protein).     

Effects of dietary phytase on body weight gain, body composition and bone strength in growing rats fed a low-zinc diet

Phytic acid, a major phosphorous storage compound found in foodstuffs, is known to form insoluble complexes with nutritionally essential minerals, including zinc (Zn). Phytases are enzymes that catalyze the removal of these minerals from phytic acid, improving their bioavailability. The objective of the present study was to determine the ability of dietary phytase to affect body weight, body composition, and bone strength in growing rats fed a high phytic acid, low Zn diet. Rats (n = 20) were fed either a control (AIN-93) or phytase supplemented (Natuphos, BASF, 1,500 phytase units (FTU)/kg) diet for a period of 8 weeks. Phytase supplementation resulted in increased (P<.05) bone and plasma Zn, but no change in plasma inorganic phosphorous or bone levels of Ca, Fe, or Mg. The addition of phytase to the diets resulted in a 22.4% increase (P<.05) in body weight at the end of the study as compared with rats fed a control diet. Dual x-ray absorptiometry (DXA) revealed that phytase supplementation resulted in increase lean body mass (LBM, P<.001) and increased bone mineral content (BMC, P<.001) as compared with feeding the control diet. Bone studies indicated that femurs and tibias from phytase supplemented rats had greater mass (P<.05) and were stronger (P<.05) than rats fed the control diet. This data suggest that the addition of phytase to low Zn diets results in improved Zn status, which may be responsible for beneficial effects on growth, body composition, and bone strength.     

植酸酶对草鱼和新吉富罗非鱼消化酶活性的影响

植酸酶能水解植酸络合物,释放被植酸束缚的各种营养因子,因此能有效解除植酸与内源性消化酶的结合,促进消化酶的作用。本实验在全植物性饲料中添加植酸酶,研究其对草鱼(Ctenopharyngodon idellus)和新吉富罗非鱼(Oreochromis niloticus)淀粉酶及蛋白酶比活力的影响。以全植物性饲料为阴性对照组,添加磷酸氢钙(dibasic calcium phosphate,DCP)实验组为阳性对照组,另设4个不同梯度的植酸酶实验组(250 U/kg、500 U/kg、1 000 U/kg和2 000 U/kg)。实验选取健壮、规格齐整平均体质量为(12.59±0.09)g的草鱼和平均体质量为(9.59±0.12)g的新吉富罗非鱼,分别随机分为6个组,每组5个平行,每个平行20尾鱼。养殖8周后,草鱼平均体质量(18.29±0.63)g,新吉富罗非鱼平均体质量为(24.68±1.34)g,抽样取出胃、肠和肝胰脏用来分析淀粉酶和蛋白酶比活力。结果表明,植酸酶对无胃鱼草鱼和有胃鱼罗非鱼淀粉酶及蛋白酶比活力都有显著的促进作用。相比较而言,植酸酶对罗非鱼的应用效果较明显,低剂量就能显著提高其淀粉酶及蛋白酶比活力(P<0.05)。当植酸酶添加量达到1 000 U/kg时,草鱼和罗非鱼淀粉酶及蛋白酶比活力均达到峰值,此时,罗非鱼淀粉酶和蛋白酶比活力与阳性对照组无显著差异(P>0.05),而草鱼肝胰脏蛋白酶比活力显著高于阳性对照组(P<0.05)。植酸酶2 000 U/kg实验组,罗非鱼淀粉酶和蛋白酶比活力与1 000 U/kg植酸酶实验组无显著差异(P>0.05),但草鱼肝胰脏蛋白酶比活力显著低于1 000 U/kg植酸酶实验组(P<0.05)。因此,本实验条件下,植酸酶在草鱼和新吉富罗非鱼全植物性蛋白质配合饲料中的适宜添加量均为1 000 U/kg,生产实践中可通过添加植酸酶部分替代无机磷源。     

Dietary pharmacological or excess zinc and phytase effects on tissue mineral concentrations, metallothionein, and apparent mineral retention in the newly weaned pig

Feeding pharmacological zinc (Zn) to weaned pigs improves growth, and dietary phytase improves P and Zn availability. Metallothionein (MT) increases in the duodenum, kidney, and liver of pigs fed 1000 mg Zn/kg with phytase or 2000 mg Zn/kg with or without phytase when fed for 14 d postweaning. The goal of this study was to determine the effects of feeding pharmacological Zn and phytase on tissue minerals, MT, mineral excretion, and apparent retention. Twenty-four newly weaned pigs (20 d; 7.2 kg) were individually fed twice daily, a basal diet supplemented with 0, 1000, or 4000 mg Zn/kg as Zn oxide, without or with phytase (500 phytase units [FTU]/kg) for 14 d, followed by a basal diet (100 mg Zn/kg) without phytase for 7 d. Pigs fed 4000 mg Zn/kg without phytase had higher (p=0.01) plasma, hepatic, renal Zn, renal Cu, and hepatic, renal, and jejunal MT than pigs fed the basal diet or 1000 mg Zn/kg. Duodenal MT was higher (p=0.0001) in pigs fed 1000 and 4000 mg Zn/kg than in pigs fed the basal diet. In pigs fed 1000 and 4000 mg Zn/kg, Zn loading occurred during the first 11 d of supplementation; by d 14, excess Zn was being excreted in the feces.     

大豆分离蛋白替代鱼粉对虹鳟生长性能及氮磷排泄的影响(英文)

以体重为(4.86±0.02)g的虹鳟稚鱼为实验对象,在室内循环水养殖系统中进行为期90d的生长实验。用1000 U/kg植酸酶预处理大豆分离蛋白,然后以预处理的大豆分离蛋白(Soy protein isolate,SPI)分别替代0、20%、40%、60%、80%和100%的鱼粉蛋白,配制成6种等氮(粗蛋白为44.97%)、等能(粗脂肪为13.42%)的饲料,以评估饲料中鱼粉替代量对虹鳟生长、体组成、消化率及氮磷排泄的影响。90d的养殖实验结果表明,大豆分离蛋白替代鱼粉对虹鳟生长性能和饲料利用率产生显著的影响(P<0.05)。当大豆蛋白替代水平由0增加到40%时,虹鳟的特定生长率(SGR)显著提高,随着饲料中SPI替代水平由40%增加到100%时,虹鳟的SGR显著降低(P<0.05),在S0、S20和S60试验组之间差异不显著(P>0.05)。增重率(WGR)和蛋白质效率(PER)分别在处理组之间的差异关系与特定生长率(SGR)在各组之间的变化趋势相类似;当大豆蛋白分别替代40%时,其饲料系数(FCR)显著低于其他替代组(P<0.05),当替代量超过40%后,随着替代水平的增加,FCR显著增加(P<0.05)。随着替代水平由0升高到100%,磷排泄显著降低,与之相反的是,磷沉积率显著升高。随着替代水平由0升高至40%,氮排泄逐渐降低,当替代水平由40%升高至100%,氮排泄逐渐升高,随着替代水平升高至40%,氮沉积率升高。试验证明,大豆分离蛋白替代量达到40%时,虹鳟的生长及饲料转化率达到最佳,而高比例的SPI对虹鳟的生长性能和饲料效率产生负面影响。     

Oilcakes as protein sources in supplementary diets for the growth of Cirrhinus mrigala (Ham.) fingerlings: laboratory and field studies

Five isonitrogenous diets (1-5) with 40% protein using oilcakes as protein sources were formulated and fed to Cirrhinus mrigala fingerlings maintained both under laboratory and field conditions. Water soaking of oilcakes for 24 h before incorporation in the diets helped in the reduction of antinutrient factors (phytase and tannins). Live weight gain in fish fingerlings fed on a diet containing groundnut oilcake (GNOC) was significantly (P < 0.05) enhanced in comparison to the other dietary treatments when examined at the end of a feeding schedule. Laboratory studies have further revealed that APD, PER, GPR and GER values were significantly (P < 0.05) enhanced, while those of feed conversion ratio were significantly (P < 0.05) reduced in fish fed on diet 1 containing GNOC. An analysis of water samples collected at two hourly interval from the aquaria revealed low levels of total ammonia (N-NH4+) excretion and reactive phosphate (O-PO4) production in fish fed on diet 1. Proximate carcass composition also revealed high accumulation of protein, fat, energy and phosphorus in fingerlings fed on a diet containing GNOC. Even in field studies a significant (P < 0.05) increase in mean fish weight gain and specific growth rate (SGR% d(-1)) was observed in fingerlings fed on diet 1, followed by canola (2), sunflower (3), mustard oilcake (4) and sesame (5). Water and sediment quality characteristics also correlated well with fish growth.     

Dietary valine requirement of juvenile blunt snout bream (Megalobrama amblycephala Yih, 1955)

An 8‐week feeding trial was carried out to test the hypothesis that adequate dietary valine might improve growth, feed utilization and protein content in blunt snout bream, whereas a valine deficiency might have adverse effects on these parameters. Six isonitrogenous (34% crude protein) and isoenergetic (14.2 MJ kg^?1 digestible energy) experimental diets were formulated to contain graded valine levels (0.66, 0.95, 1.26, 1.55, 1.87 and 2.16% of dry weight) at about 0.30% increments replaced by equal proportions of glycine. At the end of the experiment the survival rate was not significantly affected by the dietary valine level. Final weight, weight gain (WG), specific growth rate (SGR), feed efficiency ratio (FER) and protein efficiency ratio (PER) increased with an increasing dietary valine level up to the 1.26% diet, and thereafter remained relatively constant. Dietary valine levels significantly affected the viscerosomatic index, but not the hepatosomatic index or condition factor. The dietary valine levels significantly affected the protein contents of whole body and plasma. Dietary valine supplementation significantly increased the plasma valine concentration, but not the levels of other branched‐chain amino acids (isoleucine and leucine). Based on SGR and FER, the optimal dietary valine requirements of juvenile blunt snout bream were determined to be 1.32% of the diet (3.88% of dietary protein) and 1.26% of the diet (3.71% of dietary protein), respectively, using broken‐line regression analysis.     

美洲鳗鲡幼鱼饲料中鱼油的适宜添加水平研究

为研究饲料中鱼油添加水平对美洲鳗鲡(Anguilla rostrata)幼鱼生长性能、消化酶、体成分及肝脏脂肪代谢的影响, 以确定美洲鳗鲡幼鱼饲料中鱼油的适宜添加水平, 选用初始体重(8.34±0.12) g的美洲鳗鲡幼鱼800尾, 随机分成5组, 每组4个重复, 每个重复40尾; 分别投喂添加0(对照组)、3%(FO3组)、6%(FO6组)、9%(FO9组)和12%(FO12组)鱼油的试验饲料, 试验期56d。结果表明, 饲料中添加鱼油显著影响美洲鳗鲡幼鱼生长性能, FO6组美洲鳗鲡幼鱼的增重率、投饵率和饲料效率显著高于其他处理组(P<0.05)。与对照组相比, 鱼油添加组美洲鳗鲡幼鱼肠道脂肪酶活性显著提高(P<0.05), 蛋白酶和淀粉酶活性显著降低(P<0.05); FO6组、FO9组和FO12组全鱼粗脂肪含量显著提高(P<0.05), 全鱼粗蛋白质含量在FO12组显著降低(P<0.05), 全鱼水分和灰分含量无显著变化(P>0.05); FO9组和FO12组脂肪酸合成酶活性显著降低(P<0.05), FO12组脂蛋白酯酶和肝脂酶活性显著升高(P<0.05)。综上, 饲料中添加适宜鱼油水平可以提高美洲鳗鲡幼鱼的生长性能, 调节肠道脂肪酶活性、全鱼粗脂肪含量和肝脏脂肪代谢酶水平或活性; 美洲鳗鲡幼鱼获得最佳增重率和饲料效率时, 饲料中鱼油添加水平推荐为6.43%—6.78%。     

Effect of inorganic phosphate supplementation on egg production in Hy-Line Brown layers fed 2000 FTU/kg phytase

Phytase has long been used to decrease the inorganic phosphorus (Pi) input in poultry diet. The current study was conducted to investigate the effects of Pi supplementation on laying performance, egg quality and phosphate–calcium metabolism in Hy-Line Brown laying hens fed phytase. Layers (n = 504, 29 weeks old) were randomly assigned to seven treatments with six replicates of 12 birds. The corn–soybean meal-based diet contained 0.12% non-phytate phosphorus (nPP), 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase. Inorganic phosphorus (in the form of mono-dicalcium phosphate) was added into the basal diet to construct seven experimental diets; the final dietary nPP levels were 0.12%, 0.17%, 0.22%, 0.27%, 0.32%, 0.37% and 0.42%. The feeding trial lasted 12 weeks (hens from 29 to 40 weeks of age). Laying performance (housed laying rate, egg weight, egg mass, daily feed intake and feed conversion ratio) was weekly calculated. Egg quality (egg shape index, shell strength, shell thickness, albumen height, yolk colour and Haugh units), serum parameters (calcium, phosphorus, parathyroid hormone, calcitonin and 1,25-dihydroxyvitamin D), tibia quality (breaking strength, and calcium, phosphorus and ash contents), intestinal gene expression (type IIb sodium-dependent phosphate cotransporter, NaPi-IIb) and phosphorus excretion were determined at the end of the trial. No differences were observed on laying performance, egg quality, serum parameters and tibia quality. Hens fed 0.17% nPP had increased (P < 0.01) duodenum NaPi-IIb expression compared to all other treatments. Phosphorus excretion linearly increased with an increase in dietary nPP (phosphorus excretion = 1.7916 × nPP + 0.2157; R² = 0.9609, P = 0.001). In conclusion, corn–soybean meal-based diets containing 0.12% nPP, 3.8% calcium, 2415 IU/kg vitamin D₃ and 2000 FTU/kg phytase would meet the requirements for egg production in Hy-Line Brown laying hens (29 to 40 weeks of age).     

Vitamin E increases natural cytotoxic activity in seabream (Sparus aurata L.).

The natural cytotoxic activity of head-kidney leucocytes from gilthead seabream (Sparus aurata L.), after in vitro and in vivo vitamin E treatment, against tumor cells was studied by flow cytometry. Leucocytes were incubated in culture medium with different vitamin E supplementations (0.01-10 microg ml(-1)) for 6, 24 or 48 h and the results demonstrate that all the assayed vitamin E supplementations significantly enhanced the natural cytotoxic activity of leucocytes. To determine the effect of a high dietary level of vitamin E on this activity, fish were fed with 0 (control), 600, 1200 or 1800 mg of vitamin E supplementation kg(-1) diet for 2, 4 or 6 weeks. After 2 and 4 weeks of treatment, the natural cytotoxic activity was significantly enhanced at the highest (1.8 g kg(-1) diet) and lowest (600 mg kg(-1) diet) vitamin E supplement dosage, respectively. No effect of the vitamin E supplemented diet on seabream leucocyte natural cytotoxic cell activity was observed after 6 weeks of treatment.