不同季节、不同出栏日龄对樱桃谷鸭蛋氨酸需要量的影响

本研究结合生产实践，采用大群生产试验方法，对标准化饲养的2847栋鸭舍，同源樱桃谷商品肉鸭2925万只，按统一饲养方式和管理程序进行生产试验。试验日粮分为前期（1～19d）、中期（20～29d）和后期（30d～出栏）3个阶段，记录各饲养阶段肉鸭的采食量、增重、死亡率。结果表明：春、夏、秋、冬肉鸭氨基酸需要量的析因模型分别为：春季：METR=0．0050BGW＋0．1818W0．75；夏李：METR：O．0055BGW＋0．1554W0．75；秋季：METR=0．0050BGW＋0．1945W0．75；冬李：METR=0．0038BGW＋0．2651W0．75。春、夏、秋、冬四个季节肉鸭的蛋氨酸维持需要分别为每千克代谢体重0．1818、0．1554、0．1945、0．265lg；肉鸭每增重lg体重需要蛋氨酸为0．005、0．0055、0．005、0．0038g。冬季肉鸭摄入的蛋氨酸用于维持需要的量高于其它季节，以夏季最少，春季与秋季肉鸭用于维持需要的蛋氨酸量相当。而肉鸭冬季用于单位增重所需的蛋氨酸最少，其他季节相近。研究同时表明，不同的出栏日龄肉鸭增重lg所需的蛋氨酸量不同，随着肉鸭出栏日龄的延长，肉鸭每增重1g所需的蛋氨酸的需要量逐渐提高。     

Effect of supplemental dietary zinc sources on the growth and carbohydrate utilization of tilapia Smith 1840, Oreochromis niloticus × Oreochromis aureus

An 8‐week feeding trial was conducted to investigate the effect of supplemental dietary zinc sources on the growth performance and carbohydrate utilization of juvenile tilapia Smith 1840, Oreochromis niloticus × O. aureus. The goal was to compare the bioavailability of two zinc sources, zinc sulphate (ZnSO₄) or zinc methionine (ZnMet), by using two practical basal diets with 350 g kg^?1 (C350) or 400 g kg^?1 (C400) carbohydrates based on wheat as the carbohydrate source. The results showed that fish fed with a diet supplemented with 60 mg kg^?1 Zn from either ZnSO₄ or ZnMet had a significantly (P < 0.05) greater specific growth rate and protein efficiency ratio than those fed with the diets of ≤30 mg kg^?1 Zn. The composition of tilapia carcass was also found to be influenced by various levels of dietary zinc from the two zinc sources. The G6P‐DH in fish fed with the 20 mg kg^?1 ZnMet diet and the PK levels in fish fed with 20 mg kg^?1 ZnSO₄ and 30 mg kg^?1 ZnMet diet were significantly (P < 0.05) higher than those in fish fed with the C400 diet. The data suggest that supplemental dietary zinc from either ZnMet or ZnSO₄ significantly affects the growth performance and carbohydrate utilization of tilapia.     

Effects of dietary methionine hydroxy analogue supplement on growth,protein deposition and intestinal enzymes activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 900 juvenile Jian carp (Cyprinus carpio var. Jian) (8.24 ± 0.03 g) were fed practical diets containing graded levels of methionine hydroxy analogue (MHA) (0, 5.1, 7.6, 10.2, 12.7 and 15.3 g kg^?1 diet) for 60 days to investigate the effects of MHA on growth, protein deposition and intestinal enzymes activities. Per cent weight gain (PWG) significantly increased with increasing levels of MHA up to a point (P < 0.05), and thereafter declined. Feed efficiency was the highest when MHA level was at 5.1 g kg^?1 diet. Feed intake (FI) significantly enhanced with dietary MHA level up to a point (P < 0.05), beyond which it plateaued. Patterns of differences in protein production value, lipid production value, intestosomatic index, folds height, lipase, chymotrypsin, γ‐glutamyl transpeptidase, Na⁺, K⁺‐ATPase, creatinekinase, glutamate‐oxaloacetate transaminase and glutamate‐pyruvate transaminase activities were the same as that in PWG, whereas the trend of plasma ammonia content was opposite. Hepatopancreas protein content, trypsin and amylase activities followed the same trend as that of FI. The optimal supplemental level of MHA for fish meal and miscellaneous meals–based diet (6.9 g methionine kg^?1 diet) for PWG was 8.2 g kg^?1 diet by the quadratic regression analysis.     

Comparative study on the utilization of crystalline methionine and methionine hydroxy analogue calcium by Pacific white shrimp (Litopenaeus vannamei Boone)

The objective of this study was to compare the supplemental effects of crystalline DL‐methionine (DL‐Met) and methionine hydroxy analogue calcium (MHA‐Ca) on growth performance of Pacific white shrimp. Eight isoproteinic (355.3 ± 2.0 g/kg diet) and isolipidic (70.0 ± 2.2 g/kg diet) diets were prepared as positive diet (20% fish meal), negative diet (15% fish meal) and DL‐Met, MHA‐Ca‐supplemented diets with the supplementation of 0.03%, 0.06%, 0.09% DL‐Met and 0.04%, 0.07%, 0.1% MHA‐Ca in negative diet respectively. Pacific white shrimp (0.92 ± 0.03 g) were fed one of the eight diets for 49 days. The results showed that dietary DL‐Met did not affect weight gain (WG) and feed conversion ratio (FCR) (p > 0.05), but the supplementation of 0.1% MHA‐Ca significantly increased WG, protein and lipid retention, and reduced FCR (p < 0.05) when compared to the negative group, and reached the similar levels as the positive control. The total free amino acids (TFAA) in haemolymph of MHA‐Ca groups and PC, NC group peaked at the 3rd hr after feeding, but the peaking time of DL‐Met groups was advanced to the 2nd hr. Activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in haemolymph of all MHA‐Ca groups peaked at the 2nd hr, but DL‐Met groups peaked at the 1st hr after feeding. The above results indicated that the supplementation of 0.1% MHA‐Ca in a low fish meal diet could improve the growth performance and feed utilization of Pacific white shrimp, but dietary DL‐Met did not significantly affect the growth.     

The effect of taurine supplementation to a plant‐based diet for barramundi (Lates calcarifer) with varying methionine content

The effect of variable taurine inclusion (Tau) (1 g/kg DM to 15 g/kg DM) in the diet of juvenile barramundi (Lates calcarifer) on growth and nutrient utilization was investigated at three levels of dietary methionine (Met) supplementation. Diets were fed to juvenile barramundi (starting weight: 26.8 g) twice daily under a restricted pair‐fed regime for a period of 42 days. No significant effect of dietary Tau supply on growth or nutrient utilization was observed at any level of Met inclusion. Numerical variations suggested a positive effect of Tau provision at the mid‐level of supplementation (6–8 g/kg DM). The best‐fit response model (5‐SKM), fitted to the percentage body weight gain data of fish fed diets with an adequate level of Met, suggested a relatively weak pattern of response (R² = 0.183) and predicted a Tau requirement of 5.47 g/kg DM (9.64 g/kg CP) similar to that reported for several other species. It was concluded that taurine appears to be conditionally essential to barramundi, whereby provision in the diet when sulphur amino acid supply is insufficient to meet biosynthetic demands may be beneficial, but that the predicted requirement is likely reasonably accurate for use as a minimum level of inclusion.     

Lipid peroxidation,protein oxidant and antioxidant status of muscle and serum for juvenile Jian carp (Cyprinus carpio var. Jian) fed grade levels of methionine hydroxy analogue

Lipid peroxidation, protein oxidation and antioxidant status of serum and muscle in juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of methionine hydroxy analogue (MHA: 0, 5.1, 7.6, 10.2, 12.7, 15.3 g kg^?1 diet) for 60 days were investigated. Both malondialdehyde and protein carbonyl content in serum and muscle decreased with increasing dietary MHA level up to 5.1–10.2 g kg^?1 diet (P < 0.05). Anti‐hydroxyl radical and activities of catalase, glutathione peroxidase and glutathione reductase in muscle and serum, as well as anti‐superoxide anion, superoxide dismutase activity and glutathione content in serum, increased with optimal MHA supplement (P < 0.05). Meanwhile, glutathione‐S‐transferase activity in serum showed a downward trend with dietary MHA up to 7.6 g kg^?1 diet (P < 0.05). These results indicated that MHA improved antioxidant status and depressed lipid and protein oxidation in serum and muscle.     

Effect of dietary protein reduction with lysine and methionnine supplementation on growth performance,body composition and total ammonia nitrogen excretion of juvenile grass carp,Ctenopharyngodon idella

A 63‐day growth trial was undertaken to estimate the effects of supplemented lysine and methionine with different dietary protein levels on growth performance and feed utilization in Grass Carp (Ctenopharyngodon idella). Six plant‐based practical diets were prepared, and 32CP, 30CP and 28CP diets were formulated to contain 320 g kg^?1, 300 g kg^?1 and 280 g kg^?1 crude protein without lysine and methionine supplementation. In the supplementary group, lysine and methionine were added to formulate 32AA, 30AA and 28AA diets with 320 g kg^?1, 300 g kg^?1 and 280 g kg^?1 dietary crude protein, respectively, according to the whole body amino acid composition of Grass Carp. In the groups without lysine and methionine supplementation, weight gain (WG, %) and specific growth rate (SGR, % day^?1) of the fish fed 32CP diet were significantly higher than that of fish fed 30CP and 28CP diets, but no significant differences were found between 30CP‐ and 28CP‐diet treatments. WG and SGR of the fish fed 32AA and 30AA diets were significantly higher than that of fish fed 28AA diets, and the performance of grass carp was also significantly improved when fed diets with lysine and methionine supplementation (P < 0.05), and the interaction between dietary protein level and amino acid supplementation was noted between WG and SGR (P < 0.05). Feed intake (FI) was significantly increased with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05), but feed conversion ratio (FCR) showed a significant decreasing trend (P < 0.05). Two days after total ammonia nitrogen (TAN) concentration test, the values of TAN discharged by the fish 8 h after feeding were 207.1, 187.5, 170.6, 157.3, 141.3 and 128.9 mg kg^?1 body weight for fish fed 32CP, 32AA, 30CP, 30AA, 28CP and 28AA diets, respectively. TAN excretion by grass carp was reduced in plant‐based practical diets with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05). The results indicated that lysine and methionine supplementation to the plant protein sources‐based practical diets can improve growth performance and feed utilization of grass carp, and the dietary crude protein can be reduced from 320 g kg^?1 to 300 g kg^?1 through balancing amino acids profile. The positive effect was not observed at 280 g kg^?1 crude protein level.     

蛋氨酸锌在奶牛生产中的应用

蛋氨酸螯合锌是一种新型有机矿物元素添加剂,被称为第3代微量元素添加剂;由于其稳定性好、生物效价高、易消化吸收、抗干扰性强等特点,迅速成为动物营养研究的热点,并在各种动物生产中得到广泛应用。作者就蛋氨酸锌在奶牛实际生产中的相关应用研究进行综述,并对其应用前景进行探讨。     

日粮锌源和锌水平对断奶仔猪血清及组织铜、铁、锌沉积的影响

选用临床检查健康的(26±2)日龄"杜×长×大"三元杂交断奶仔猪100头,按体质量和性别随机分为5组,每组20头,分别饲喂基础日粮、基础日粮+2000mg/kg氧化锌、基础日粮+3000mg/kg氧化锌、基础日粮+250mg/kg蛋氨酸锌、基础日粮+500mg/kg蛋氨酸锌。试验期14d。于断奶后0,7,14d,经前腔静脉采血,用原子吸收光谱仪检测血清中铜、铁、锌水平。试验结束时,每组选5头仔猪放血致死,取心、肝、肾、脑、脾、胸腺组织,测定铜、铁、锌含量。结果显示,仔猪断奶后,血清中铜、锌水平显著或极显著下降(P0.05或P0.01);添加不同锌源和锌水平的高锌日粮能提高断奶仔猪肝、肾、脑、血清锌的含量,显著或极显著降低仔猪血清铜和心、胸腺铜以及脾铁水平(P0.05或P0.01),对血清铁及其他组织铁含量无明显影响。这表明高锌日粮能增加断奶应激仔猪体内锌水平,降低部分组织中铜、铁含量。     

蛋氨酸缺乏对蛋鸡产蛋后期生产性能、血清游离氨基酸含量和肝脏蛋氨酸代谢相关基因表达的影响

本试验旨在研究蛋氨酸缺乏对蛋鸡产蛋后期生产性能、血清游离氨基酸含量和肝脏蛋氨酸代谢相关酶基因表达的影响。选取180只62周龄的海兰灰蛋鸡,根据产蛋率均匀分成3组(每组6个重复,每个重复10只):对照组饲喂蛋氨酸水平为0.33%的饲粮,蛋氨酸缺乏组分别饲喂蛋氨酸水平为0.21%和0.27%的饲粮,试验期90d。结果表明:1)饲粮蛋氨酸缺乏显著降低了蛋鸡的平均日采食量、产蛋率、平均日产蛋重、平均蛋重和不合格蛋率(P0.05),显著提高了料蛋比(P0.05)。2)蛋氨酸缺乏显著降低蛋鸡血清中蛋氨酸的含量(P0.05)。0.21%蛋氨酸组蛋鸡血清中丝氨酸、甘氨酸和丙氨酸的含量显著高于其他2组(P0.05)。0.27%蛋氨酸组蛋鸡血清中缬氨酸、异亮氨酸和精氨酸的含量显著低于对照组(P0.05),脯氨酸的含量显著低于0.21%蛋氨酸组(P0.05)。3)与对照组相比,0.21%蛋氨酸组蛋鸡肝脏中DNA甲基转移酶1、N6-甲基腺苷(m6 A)甲基转移酶3(METTL3)和m6 A甲基转移酶14的表达量显著提高(P0.05),0.27%蛋氨酸组蛋鸡肝脏中METTL3的表达量显著提高(P0.05)。4)与对照组相比,0.21%蛋氨酸组蛋鸡肝脏中甲硫氨酸腺苷转移酶1a、5-甲基四氢叶酸-同型半胱氨酸甲基转移酶(MTR)和胱硫醚-β-合成酶的表达量显著提高(P0.05),0.27%蛋氨酸组蛋鸡肝脏中MTR的表达量显著提高(P0.05)。蛋氨酸缺乏对蛋鸡肝脏甲硫氨酸腺苷高半胱氨酸酶和甜菜碱高半胱氨酸甲基转移酶的表达量无显著影响(P0.05)。由以上结果可知:蛋鸡饲粮高水平的蛋氨酸缺乏会降低蛋鸡的生产性能,可能与蛋氨酸缺乏改变蛋氨酸代谢途径,影响DNA和RNA的甲基化过程有关。