早期营养限制对肉鸡生长性能和胴体品质的影响

本文研究了早期长时间(1~21日龄)低强度(每日4 h)营养限制对肉鸡生长性能和胴体品质的影响。选择健康、体重相近1日龄安康红肉用公母混合雏鸡600羽,随机分成2个组(对照组与试验组),每个组300羽(含3个重复,每个重复100羽)。饲养试验分3个阶段:1~21、22~42和43~63日龄。试验组1~21日龄每日10:00~14:00实施限饲(不给料),22~63日龄恢复自由采食,对照组全期自由采食。所有试验鸡在自由饮水和24 h光照条件下进行为期63 d的饲养试验。限饲结束(21日龄)和饲养试验结束(63日龄)后,每个组的每个重复选择母鸡8羽(共96羽)进行屠宰试验与取样分析。结果表明,肉鸡早期低强度(12.59%限饲量)长时间(1~21日龄)的连续限饲方案显著降低了1~21日龄肉鸡生长速度;22~63日龄恢复自由采食后获得了明显的补偿生长,饲料转化率各阶段差异均不明显(P>0.05)。早期限饲明显改变了21、63日龄肉鸡的胴体组成和肉质,显著提高上市肉鸡(63日龄)腿肌重而不影响胸肌重,提高胸肌蛋白含量而降低脂肪含量,同时明显增加了腹脂沉积量。上述结果提示,早期营养限制对肉鸡具有代谢程序化和营养重分配的作用,能显著改变肉鸡的胴体品质。     

植酸酶基因PhyB1的克隆及序列分析

为了进一步研究多种植酸酶之间的相互作用,利用PCR技术,从黑曲霉WP1中克隆出植酸酶PhyB基因,该基因长1 560 bp,含有3段内含子,共编码460个氨基酸,与已报道的ALKO243的植酸酶Aph基因(GeneBank Acces-sion:L02420)相比较,编码的氨基酸序列同源性为99.13%,因此将其命名为PhyB1。该基因含有植酸酶保守序列“RHGXRXP”和“HD”。黑曲霉WP1植酸酶PhyB1基因序列已在国际基因库中注册,注册号为:DQ836360。     

太白蓼多糖的硫酸化修饰及其体外抑菌活性分析

建立并优选太白蓼多糖(Polygonum taipaishanease Kung polysaccharide,PTKP)硫酸化修饰的条件,探讨硫酸化修饰对太白蓼多糖抑菌活性的影响。以硫酸根取代度为指标,采用氯磺酸-吡啶法对太白蓼多糖进行修饰,以氯磺酸-吡啶比、反应时间和反应温度为因素水平,采用L9(34)正交试验对修饰条件进行优选。用氯化钡-明胶浊度法测定修饰产物的硫酸基取代度(DS),傅里叶红外变幻光谱法测其结构,微量法测定硫酸化太白蓼多糖(sulfated Polygonum taipaishanease Kung polysaccharide,sPTKP)对大肠杆菌和志贺氏菌的最小杀菌浓度。太白蓼多糖硫酸化修饰的最佳条件为氯磺酸与吡啶体积比为1∶10,反应温度为80℃,反应时间为1h,sPTKP的硫酸基取代度为1.57。红外光谱检测到S=O的伸缩振动峰。PTKP和sPTKP对大肠杆菌和志贺氏菌均有抑制作用,它们对志贺氏菌的抑制作用优于大肠杆菌。硫酸化修饰能提高太白蓼多糖对大肠杆菌和志贺氏菌的体外抑菌活性。     

Preliminary study on the use of ceftazidime, a broad spectrum cephalosporin antibiotic, in snakes

Ceftazidime, a broad spectrum cephalosporin antibiotic with an enhanced anti-pseudomonal activity, was tested in vitro against a variety of reptilian bacterial isolates. Blood concentrations of this antibiotic were determined in clinically ill snakes following an intramuscular injection at a dose rate of 20 mg kg-1. Peak plasma levels of up to 70.5 micrograms ml-1 were reached one to eight hours after the injection and therapeutic plasma levels were maintained for at least 96 hours. A series of snakes treated with ceftazidime at a dose rate of 20 mg kg-1 every 72 hours showed a rapid and obvious clinical response to treatment. The snakes were maintained at 30 degrees C during treatment and the effect of environmental temperature on antibiotic half-life is discussed. Ceftazidime proved to be a highly active antibiotic against the bacteria known to cause disease in reptiles, with no obvious adverse effects having been so far described.     

Evaluation of Soybean Meal-Red Blood Cell Coextruded Feed Ingredient in Diets Fed to Rainbow Trout Oncorhynchus mykiss

Abstract.— Fish meal is one of the predominant sources of crude protein used in practical feeds for most cultured species. However, with overfishing and increasing demand for protein feedstuffs, new competitively priced sources of dietary protein are needed. A coextruded soybean meal-red blood cell (SBM-RBC) ingredient was evaluated as a source of crude protein for rainbow trout Oncorhynchus mykiss . The SBM-RBC ingredient was incorporated at either 0, 21, 42 or 63% of the dietary protein, replacing an isoni-trogenous amount of fish meal. All diets were fed for 8 wk to triplicate groups of juvenile rainbow trout (average initial weight 49.5 g) stocked into a recirculating system consisting of 48, 114-L aquaria. There were no significant differences in weight gain, feed conversion ratio, protein efficiency ratio, apparent crude protein digestibility, apparent gross energy digestibility, dress-out percentage, or fillet protein and fat concentrations in fish fed any of the experimental diets. Based on these data, extruded SBM-RBC appears to be a suitable ingredient in diets fed to rainbow trout.     

Neck and shoulder motion of the gallop stride

The motion patterns of the neck and shoulders during the gallop stride were documented using high-speed cinematography. The gallop stride characteristics of 4 Quarter Horse fillies, approximately 30 months of age, were used as a model. Horses were housed and fed together and received the same amount and type of limited training; and were all ridden with the same tack and by the same person. Both sides of each horse were filmed simultaneously (243 frames/sec) while galloping individually along a 1.5-m-wide track. Kinematic variables describing 29 strides (mean velocity 13.1 m/sec, stride frequency 2.6 strides/sec, stride length 5.1 m) included linear and temporal measurements of the maximum and minimum heights of the wing of the atlas, spine of the scapula, shoulder joint and elbow joint; maximum and minimum angles with respect to the horizon of the neck, shoulder and arm segments; and maximum and minimum relative angles between the neck and shoulder, and shoulder and arm segments. Differences (P<.05) between the leading and trailing sides of the body were identified for 12 of a total of 27 spatial measurements reported for the neck, shoulder and arm, including minimum height of the scapula spine, maximum height of the scapula spine and elbow joint, maximum absolute angle of the shoulder segment, and minimum angle between neck and shoulder segments. Of 18 temporal measurements reported involving the neck, shoulder and arm, 14 differed (P<.05) between leading and trailing sides. Kinematic events describing the motion of the leading and trailing shoulder and arm segments were ordered and tabulated in the temporal sequence of the normal gallop stride. Results indicated that the motion patterns of the shoulder and arm segments were highly specific to the leading and trailing sides of the body in the equine gallop stride. The work required for vertical displacement of the center of mass in galloping was estimated to be approximately 98,500 J/km or 23.5 kcal/km; equivalent to approximately 6 percent of the total energy expenditure for galloping 1 km.     

Nutrition and fuel utilization in the athletic horse

Substrate depletion and end product accumulation are two important factors in exercise fatigue. Fatigue during long-term exercise results from a depletion of muscle and liver glycogen and coincides with an inability to maintain blood glucose levels. During high intensity exercise, the rapid catabolism of carbohydrate and the resultant production of lactate and hydrogen ions cause a reduction in muscle pH that inhibits maximum force generation. Dietary manipulations that can influence carbohydrate status or lactate accumulation may be beneficial to performance. In human athletes, carbohydrate loading and carbohydrate supplementation can enhance endurance time during long-term exercise. These practices have not been explored extensively in the equine athlete, although glycogen loading does not enhance the performance of horses during short-term intense work. Short-term work can be detrimentally affected if glycogen levels are inadequate. The most marked effect of exercise on nutrient requirements is in the energy requirement. Horses in heavy training may require more energy than they can consume on a conventional diet. Fat has been added to horse diets to increase energy density, usually at levels between 6% and 12% of the total diet. Although protein requirements may be slightly increased in the working horse, supplementing protein as a means of adding calories is not an efficient practice. In addition, although studies with horses are not available, human studies indicate that there are no benefits to vitamin supplementation above required levels. At this point, more is unknown than is known about feeding performance horses. Most information on fuel utilization is extrapolated from studies with rats and humans. Areas that have received little attention but are critical to optimizing feeding practices are the timing of pre-event feeding and the determination of ideal body composition in equine athletes of different types.     

Environmental and managerial determinants of somatic cell counts and clinical mastitis incidence in Ohio dairy herds

A stratified-random sample of 48 Ohio dairy herds participated in a 1-year disease monitoring survey to study herd management and environmental conditions affecting udder infection and clinical mastitis incidence. The mean monthly bulk-tank somatic cell count was used as an indicator of overall udder infection. Clinical incidence was determined by monthly on-farm interviews with the dairy producers. Management and environmental conditions were assessed by direct observation as well as by personal interview of dairy managers. The final multivariable analysis-of-variance model of log bulk-tank somatic cell count had an R² value of 0.43. Lower log bulk-tank somatic cell count was found in herds with hired milkers, a clean and dry cow exercise area, clean teats following milking and fewer milking cows. The number of months spent on pasture was also significant. The final model for clinical mastitis incidence had an R² value of 0.38. Less clinical mastitis was found on farms where straw bedding was used, pre-dip was not used, where there were fewer cows, fewer person-hours per cow were spent milking cows, a greater percentage of calvings occurred in the designated calving facility, and cows spent fewer months per year on pasture. Other potentially important disease determinants could not be included in the final models because of limited sample size relative to the model degrees of freedom (six each).