Numbers of airborne bacteria and fungi in calf houses

Counts of airborne bacteria colony forming particles (BCFP) and fungi were made at intervals throughout one year in three calf houses using a six stage Andersen Sampler. House 1 was insulated, mechanically ventilated and heated, House 2 was insulated and provided with a controlled natural ventilation system, while House 3 was uninsulated with natural ventilation. Each house contained 36 bought-in bull calves. Every six weeks the 12 oldest calves were removed and replaced by 12 four-week-old calves. The mean count of BCFP was highest in House 2 (101.6 X 10(3) m-3) and lower in House 3 (67.6 X 10(3) m-3). The mean count of aerial fungi was significantly lower in House 3 (40.5 X 10(3) m-3) than in Houses 1 and 2 (119.3 X 10(3) m-3 and 127.1 X 10(3) m-3, respectively). The count of aerial BCFP and fungi showed large seasonal fluctuations, but there was a general trend towards lower counts during the winter period. The mean incidence rate of respiratory disease among the experimental calves was 67.7%. The highest mean incidence rate was recorded in House 2, but differences between houses were not significant. The results are discussed in relation to the environmental requirements for raising of calves, and in the light of the current concept of air hygiene as a major predisposing factor in the web of causation of calf respiratory disease.     

羊舍气载真菌的浓度及分布特征

采用6级Andersen空气生物采样器,以孟加拉红培养基为培养介质,测定并分析羊舍气载真菌浓度、分布特征及与环境的关系,以期为羊舍的环境控制提供依据。结果表明,羊舍内真菌气溶胶浓度为2 855(±1 806)~3 698(±3 087)CFU/m3;9∶00左右浓度最低,显著低于13∶00和17∶00(P<0.05);真菌粒子主要分布在采样器第3~5级,粒径<5μm的真菌粒子约占80%,可侵入肺泡;与环境因素的相关性分析表明,空气真菌含量与环境因素有显著的线性关系,与温度呈正相关,与相对湿度呈负相关。     

Air microorganisms in animal housing--4. Airborne gram-negative bacteria and airborne endotoxin in pig houses

The species composition of airborne gram-negative bacteria and the relationship between inhalable endotoxin, inhalable dust and airborne bacteria were studied in 4 pig houses. The airborne gram-negative bacterial flora was dominated by Enterobacteriaceae. Within the Enterobacteriaceae the species E. coli and Enterobacter agglomerans were predominant. Significant correlation were found between the concentration of inhalable dust and inhalable endotoxin as well as between the concentration of airborne gram-negative bacteria and inhalable endotoxin. However these correlation were not very strong. With respect to the characterization of the potential hazard of organic dust exposure, measurements of the concentration of airborne dust or airborne bacteria should not be used for the estimation of the concentration of airborne endotoxin.     

Limulus test--a rapid and simple method for the detection of endotoxins produced by gram-negative bacteria in mastitis milk

According to the present study the limulus amebocyte lysate test (LAL) seems to be a convenient test to detect endotoxin in milk from udder quarters with and without inflammation. The correlation between endotoxin concentration and the results from the bacteriological investigation of 79 milk samples was good (Table I). Determination of endotoxin in 20 milk samples from cases of acute clinical mastitis with high cell count and a negative bacteriological culture showed that all but one had an endotoxin concentration of greater than 1.0 ng/ml milk (Table II). By using a micromethod of the LAL it is possible to detect cases of mastitis caused by gram-negative bacteria about one hour after the sample has reached the laboratory. In a preliminary field study milk from 13 cases of acute clinical mastitis were tested by a modified limulus amebocyte lysate (LAL) test ("cowshed test"). A 100% correlation to bacteriological findings was observed (Table IV). By using the LAL test to detect mastitis cases caused by gram-negative bacteria great economic advantages and less risk for resistance problems can be achieved by using proper antibiotics. This is the fact in Sweden where the frequency of acute clinical mastitis caused by streptococci (100% of strains sensitive for penicillin) and Staphylococcus aureus (about 90% of strains sensitive for penicillin) is high (70-80%) and about 20% are caused by gram-negative bacteria, mostly E. coli.     

Investigations on airborne microorganisms in animal stables. 3: Relationship between inhalable endotoxin, inhalable dust and airborne bacteria in a hen house

The relationship between inhalable endotoxin, inhalable dust and airborne bacteria was studied in a hen house. Neither the concentration of inhalable dust nor the concentration of airborne bacteria are suitable to reflect the concentration of airborne endotoxin. Furthermore it was found that the endotoxic activity can persist over a long period of time in dust samples. Therefore an accumulation of endotoxin in different environments is possible. Airborne endotoxin seems to be a suitable marker to characterize exposure to airborne organic dust, since this toxin is responsible for different respiratory diseases (e.g. toxic pneumonitis, airway obstructions) and the toxic activity of endotoxin in dust samples is known to persist for a long time.     

Pathophysiological effects of endotoxins in ruminants

Summary

Metabolic disturbances following intravenous and intramammary administration of endotoxins in ruminants are described. In contrast to the similarity in response of blood biochemical parameters after intravenous and intramammary administrations of endotoxins, responses in plasma concentrations of enzyme activities, the thyroid hormones, cortisol, and somatotropin differ markedly. Biochemical changes in blood after endotoxin administration are predominantly dose‐dependent; thus some of the biochemical parameters ‐ especially plasma concentrations of Fe and Zn ‐ serve also to evaluate the effects of certain drugs in endotoxin models.

Changes in milk composition have been documented only after intramammary infusion of endotoxins and can partly be explained by the increased permeability of the blood/milk barrier. Appearance and production of milk returns to normal within a week after intramammary endotoxin treatment, indicating that the mammary gland is only temporarily damaged by endotoxin‐induced mastitis.     

河北省不同地区夏季规模化羊场气载细菌的检测与分析

旨在研究河北省夏季不同地区规模化羊场气载细菌的日变化和区域性变化。选择3个区域(燕山丘陵、太行山区和平原地区)10个规模化羊场(14个舍),采用定点采样和培养计数法,对夏季各羊舍及其运动场的细菌数量进行3 d连续检测。结果:羊舍和运动场细菌数量表现为中午低、早或晚高的变化规律,早、中、晚不同地区羊舍的细菌数量分别为6.23×10^3~9.78×10^3、5.05×10^3~6.56×10^3和6.05×10^3~7.51×10^3 cfu/m^3,其中太行山区羊舍细菌在3个时间段间达显著差异(P<0.05)。从区域性分布看,太行山区羊舍细菌数量高于其他2个地区,燕山、太行和平原3个地区羊舍细菌平均数量分别达6.76×10^3、7.79×10^3和6.01×10^3 cfu/m^3;羊舍与运动场比较,虽然太行山区和平原地区羊舍细菌与运动场之间无显著性差异(P>0.05),但太行山区羊舍及其运动场的细菌数量有增加趋势(P=0.05,P=0.07),而燕山丘陵50%的羊舍细菌数量显著高于运动场(P<0.05)。另外,比较4类羊(妊娠、母带仔、育成和育肥)舍细菌得出,妊娠舍细菌平均数量最高(7.10×10^3 cfu/m^3),育肥舍或带仔母羊舍细菌数量最低(5.54×10^3 cfu/m^3,5.55×10^3 cfu/m^3)。该研究结果可为完善羊场的羊舍设计和环境调控提供可靠依据。     

嗜热毛壳菌纤维素酶对肉兔生长性能和消化性能的影响

24只新西兰肉兔分为4组,每组6只,研究日粮中添加5、10、15g/d·只纤维素酶与不加酶对其生长性能和消化性能的影响。结果表明:添加5、10、15g/d纤维素酶组平均日增重比对照组分别提高7.2%(P<0.01)、14.47%(P<0.01)、19.45%(P<0.01);兔粪中粗蛋白质含量比对照组分别减少了7.68%(P<0.05)、3.80%(P<0.05)、1.62%(P>0.05);中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的含量较对照组分别降低28.22%(P<0.01)、19.86%(P<0.01)、17.93%(P<0.01)和2.69%(P>0.05)、14.19%(P<0.05)、19.40%(P<0.05);经济效益以添加10g为最好,每千克增重节省成本0.59元。     

冬季畜禽舍的保温与供暖

冬季畜禽的疾病较少．如果能保证供暖．存活率高，饲料报酬好．冬季更能成功地饲养畜禽。畜禽的环境控制包括对温度、湿度、通风等全而的控制．而保温与供暖是冬季控制好环境的基础，是冬季能否成功饲养畜禽的关键。     

Effect of electrostatic space charge on reduction of airborne transmission of Salmonella and other bacteria in broiler breeders in production and their progeny

Salmonella in birds is a concern because of the human foodborne illness associated with the consumption of poultry meat and eggs. One of the methods of transmission of Salmonella within a flock can be by the air. Therefore, we used reduction of transmission of Salmonella to monitor the effectiveness of the electrostatic space charge system (ESCS). During the average broiler breeder laying cycle of 40 wk, a large amount of dust becomes airborne and accumulates on walls, ceiling, and equipment. Many microorganisms adhere to these dust particles, making dust an excellent vector for horizontal disease transmission between birds.We used two environmentally controlled rooms containing commercial broiler breeders to evaluate the effectiveness of an ESCS that produced a strong negative electrostatic charge to reduce airborne dust and, subsequently, microorganism levels. The ESCS caused the dust to become negatively charged, therefore moving to the grounded floor in the treatment room. The use of the ESCS resulted in a significant reduction (P < 0.0001, 61% reduction) in airborne dust concentration levels, which resulted in a significant reduction (P < 0.0001, 76% reduction) in total airborne bacteria and gram-negative bacteria (48% reduction) in the treatment room. Significant reductions (P < 0.05) of gram-negative bacteria (63% reduction) on the egg collection belts were also recorded in the treatment room, which resulted in a significant reduction (P < 0.0001) of gram-negative bacteria (28% reduction) on the eggshell surface. The ESCS treatment resulted in fewer Salmonella enteritidis-positive hens and their progeny from the treatment room due to reductions of dust and airborne bacteria. In addition, this significant reduction in bacteria on the eggshell surface should result in less bacteria in the day-old chicks, therefore better early chick livability. There was no significant difference (P > 0.05) in egg production, male or female body weights, mortality, or reproductive performance in the ESCS room compared with the control room.     

注射用盐酸土霉素的细菌内毒素检查

参照<中国兽药典>二○○○年版一部附录细菌内毒素检查法,研究了注射用盐酸土霉素对细菌内毒素检测的干扰情况,确定0.312 5 mg/mL浓度的供试品溶液对检测无干扰作用,建立了注射用盐酸土霉素的细菌内毒素限量检查方法.     

肉鸡舍的最佳气候条件与通风方式

近30年来,全球的家禽业获得了长足的发展.其中的许多成就来源于对肉鸡快速生长和理想饲料报酬的选育.目前,肉鸡在42日龄的体重要比10年前高出0.45千克.遗传学家和大型肉鸡场已把最大的重点放在进一步提高肉鸡的生长率、饲料报酬和胸肉产量上.他们估计到2005年,肉用仔鸡在28日龄时体重可达到1.8千克.但只有在生产者放弃传统的饲养系统,采用现代饲养技术,使肉鸡的饲养环境和管理达到最佳水平才能取得这些遗传进展.在获取肉鸡最佳生产性能的许多变量中,最重要的因子之一是通过正确通风获取较好的空气质量.