不同饲养水平下灌注氨基酸对阉牛氮代谢的影响

选择 6头体重 5 0 0～ 6 0 0kg ,安装有瘤胃、十二指肠前端和回肠末端瘘管的阉牛 ,分 3期依次饲喂以玉米、棉粕和氨化稻草为原料配合的 3种不同饲养水平的日粮。每种饲养水平下 ,依次从十二指肠灌注 4种不同的氨基酸混合液 ,测定相应的氮平衡值、血清尿素和血清游离氨基酸浓度。其中 ,饲喂高水平日粮时 ,4种灌注处理分别为 :Lys+Met+Thr、Met+Thr、Lys+Thr和Lys+Met;饲喂中等水平和低水平日粮时 ,4种灌注处理分别为 :Lys+Met+Val、Met+Val、Lys+Val和Lys+Met。结果显示 ,3种饲养水平下 ,不同灌注处理对氮平衡值有显著影响 (P <0 0 5 )。在高水平日粮条件下 ,与Lys +Met+Thr处理相比 ,回撤Lys、Met和Thr时 ,氮平衡值分别减少了 10 2 3、8 83和 7 2 8g/d(P <0 0 5 ) ;在中等水平的日粮条件下 ,与Lys+Met+Val处理相比 ,回撤Lys、Met和Val时 ,氮平衡值分别减少了 5 4 1、3 4 1和 1 6 0 g/d(P <0 0 5 ) ;在低水平日粮条件下 ,与Lys +Met+Val处理相比 ,回撤Lys、Met和Val时 ,氮平衡值分别减少了 8 4 5、5 14和 2 78g/d(P <0 0 5 ) ,各种回撤处理间的氮平衡也差异显著 (P <0 0 5 )。 3种饲养水平下 ,血清尿素、血清总游离氨基酸和除被撤氨基酸外的各种游离氨基酸浓度随灌注处理不同而变化的趋势与氮平     

Inhibition of powdery mildew development and activation of antioxidant enzymes by induction of oxidative stress with foliar application of a mixture of riboflavin and methionine in cucumber

Powdery mildew (Sphaerotheca fuliginea Pollacci) infection in cucumber was significantly reduced by foliar application of a mixture of riboflavin and methionine (RM). The effects of fungicidal activity on leaves applied with RM were detected through restriction of progress of colonies and disease severity compared with control plants. The initial response to foliar application of RM was abrupt generation of hydrogen peroxide in the leaves of cucumber plants. Activities of antioxidant enzymes such as SOD and POD were abruptly increased by foliar application of RM. However, activities of antioxidant enzymes in control plants were increased with disease development 9 d after pathogen inoculation. Cucumber leaves have six major SOD isoforms. When plants were foliar-applied with RM, densities of three SOD isozyme bands at SOD-1, SOD-2, and SOD-3 were increased 3 d after foliar application. Leaves of cucumber plants have three major POD isozyme bands. Densities of three POD isozyme bands were increased 3 d after foliar application with RM. Four major PPO isozyme bands were determined in cucumber leaves. Though the overall banding patterns of PPO in control and RM-applied plants were similar, the band profiles in leaves applied with RM were characterized by high densities of the three major isoforms. Activities of PPO in leaves applied with RM increased rapidly during the 3 d after foliar application, and then remained relatively constant for 15 d. Although activities of PPO in the leaves of control plants also abruptly increased after 9 d, it was lower than those of RM-applied plants during the whole time. The difference in lignin content between control and RM-applied plants was detected 9 d after foliar application; it was high in leaves applied with RM.     

Milk production in Holstein cows supplemented with different levels of ruminally protected methionine

Forty multiparous cows (599 kg ± 18 kg BW) were fed with a basal diet (19.6% CP, 35% RUP, and 1.7 Mcal kg^− 1 NEl) with alfalfa, corn silage and concentrate (49% forage: 52% concentrate). After calving, cows were randomly assigned to the treatments, which consisted in four levels of ruminally protected methionine (RPM): 0, 8, 16 and 24 g d^− 1 of Mepron®M85 (Degussa Co.). Experiment was conducted for 120 days with measurements of milk production, composition, body weight, body condition score and DM intake every 15 days (3 consecutive days) starting on day 5 postpartum. Data were analyzed with the repeated measures model (four treatments in 8 periods through lactation). No treatment effects were detected on DM intake (20.38 ± 2.51 kg d^− 1), body weight (599.78 ± 19.78 kg), body condition score (2.51 ± 0.19 units) and milk fat. However, milk production and protein yield were increased with addition of RPM (P < 0.01). Milk production responded quadratically to methionine level. Holstein cows with a mean production of 35 kg d^− 1 milk require addition of ruminally protected methionine (16 g d⁻¹) to improve milk production.     

Dietary methionine requirement of fingerling Indian major carp, Cirrhinus mrigala (Hamilton)

Indian major carp, Cirrhinus mrigala fingerling (3.85 ± 0.50 cm, 0.50 ± 0.02 g) were fed isonitrogenous and isocaloric diets (40% CP, 4.28 kcal g⁻¹, GE) containing casein, gelatin and crystalline amino acids with graded levels of L- methionine (0.50, 0.75, 1.00, 1.25, 1.50 and 2.00 g/ 100 g, dry diet) with 1.00% cystine fixed, to determine its dietary methionine requirement. A feeding trial was conducted in triplicate for six weeks. Diets were fed twice a day at 0800 and 1600 h at 5% of body weight/day. The ration size and feeding regime were worked out prior to the start of the feeding trial. Weight gain (158%) and food conversion ratio (1.45) were significantly (P < 0.05) higher in fish fed diet containing 1.00% methionine with 1.00% cystine fixed. Second degree polynomial regression analysis of the weight gain data indicated the dietary methionine requirement to be 1.20 g/100 g of dry diet, corresponding to 3.00% of dietary protein. Second degree polynomial regression analysis was also employed to determine the relationship between food conversion ratio (FCR) and dietary methionine levels which indicated that the best FCR occurred at approximately 1.20% dietary methionine level. Carcass composition of fish fed diet containing graded levels of methionine varied significantly (P < 0.05) except carcass ash content which showed insignificant (P > 0.05) differences among the dietary methionine levels. This revised version was published online in August 2006 with corrections to the Cover Date.     

蛋氨酸锌对吉戎兔体内锌、铜、铁沉积率的影响

随机选取60日龄健康吉戎兔72只,分成4个处理,每个处理3个重复,每个重复6只吉戎兔。饲养45d,每处理基础日粮相同,对照组为处理Ⅰ不添加蛋氨酸锌(Zn-Met),试验组为处理Ⅱ、Ⅲ和Ⅳ分别添加40、80、120mg·kg-1蛋氨酸锌。结果表明,随蛋氨酸锌添加量增加,组织中锌、铜和铁含量有增加趋势,但添加到Zn-Met80mg·kg-1以后这种趋势减缓并有所下降。本试验中,添加蛋氨基酸锌增加组织中锌的含量,有促进铜和铁的吸收作用。     

Quantitative dietary requirement of juvenile Atlantic ditch shrimp Palaemonetes varians for lysine,methionine and arginine

This study was carried out to estimate lysine, methionine and arginine dietary requirements of juvenile Atlantic ditch shrimp, Palaemonetes varians. Three series of five isoproteic and isoenergetic diets [45% crude protein (CP), 14.7 MJ digestible energy (DE)/kg] were formulated to contain increasing levels of either lysine (1.2–2.8 g/100 g of diet), methionine (0.5–1.3 g/100 g of diet + 0.8% cysteine) or arginine (1.1–2.7 g/100 g of diet) and adequate levels of all other essential nutrients. Each experimental diet was fed to three groups of postlarvae (initial weight = 17 mg each) for 45 days at 19.9 ± 0.1°C. The dietary requirements for maximizing weight gain of juvenile P. varians, estimated using broken‐line analysis vs. exponential model and expressed as per cent of dry diet, were 2.42 vs. 2.63; 0.96 vs. 0.99 and 2.05 vs. 2.39 for lysine, methionine and arginine respectively. These estimates of requirements of lysine, methionine and arginine for juvenile P. varians appear to be similar to those reported for penaeid shrimp species.     

蛋白质饲料鱼粉、豆粕的掺假鉴定及分析

对蛋白质饲料鱼粉和豆粕的掺假鉴定方法进行了概述.分析结果表明,蛋氨酸和赖氨酸含量可作为鉴定这两种饲料掺假与否的指标.     

日粮蛋氨酸对活拔羽毛后皖西白鹅体质和产羽性能的影响

研究了在皖西白鹅拔羽后精料补充料中添加不同水平的蛋氨酸对皖西白鹅体增重和羽绒产量的影响,结果表明:拔羽后在精料补充料中添加不同水平的蛋氨酸有利于鹅体质的恢复和新生羽毛、羽绒的生长,有助于提高活拔羽绒的产量。     

Potential importance of bacteria and fungi in nitrate assimilation in soil

Soil microorganisms can use a wide range of N compounds but are thought to prefer NH₄⁺. Nevertheless, ¹⁵N isotope dilution studies have shown that microbial immobilization of NO₃⁻ can be an important process in many soils, particularly relatively undisturbed soils. Our objective was to develop a method for measuring NO₃⁻ immobilization potential so that the relative contributions of bacteria and fungi could be determined. We modified and optimized a soil slurry method that included amendments of KNO₃, glucose, and methionine sulfoximine (an inhibitor of N assimilation) in the presence of two protein synthesis inhibitors: chloramphenicol, which inhibits bacteria, or cycloheximide, which inhibits fungi. By adding ¹⁵N-labeled KNO₃, we were able to measure gross rates of NO₃⁻ production (i.e., gross nitrification) and consumption (i.e., gross NO₃⁻ immobilization). We found that bacteria, not fungi, had the greatest potential for assimilating, or immobilizing, NO₃⁻ in these soils. This is consistent with their growth habit and distribution in the heterogeneous soil matrix.     

Effect of ruminally protected Methionine on the productive and reproductive performance of grazing <Emphasis Type="Italic">Bos indicus</Emphasis> heifers raised in the humid tropics of Costa Rica

With the objective of evaluating the effect of methionine supplementation prior to a breeding program, thirty one heifers (Bos taurus x Bos indicus) were used averaging 386  ±  29 days of age and a mean body weight of 402.6  ±  28 kg. Fifteen of the animals received a supplement (SG) during 45 days with molasses-urea mixture (2 kg molasses + 407 g urea/head/day), plus 10 g of ruminally protected methionine. The other sixteen heifers did not receive supplement (CG). Fecal and pastures samples were collected to assess dry herbage intake and digestibility. Serial ultrasound measurements from the ovary were performed in both groups to evaluate follicular dynamics. The heifers were categorized according to their follicular size and presence of a CL. Forage intake and dry matter digestibility were reduced (P  <  0.05) and body condition tended to improve (P  =  0.07) in the supplemented heifers, however, total intake, final weight, daily gain and dorsal back fat were not affected. After the supplementation period, the percentage of females in the categories < 3 mm and 3 to < 6 mm, was greater (P  <  0.05) in CG (25% and 43.7%) that in SG (0% and 26.6%) but in the follicle category of ≥  9 mm, the percentage of animals was 60% in SG and 18.8% in CG (P  <  0.05). The percentage of ovulation for the SG and CG was 86.7% and 62.5%, respectively (P  <  0.05). The combination of supplementation with methionine-urea and molasses at the end of the dry season and the anticipated onset of the rainy season favored the establishment of ovarian activity and follicular dynamics.