Effects of ascorbic acid on stress and disease in chickens.

White leghorn chickens were given feed containing 100 mg of ascorbic acid (AA)/kg. One day later, treated chickens and a similar group of unmedicated control chickens were chilled for 1 hour at 6 C, exposed to an unusual sound, fasted, or subjected to rough handling. Heterophil:lymphocyte (H:L) ratios were determined one day later. The AA-treated birds had significantly lower H:L ratios than untreated controls. Chickens that received a diet containing AA had lower H:L ratios than controls (0.86 vs. 1.65) following administration of adrenocorticotropic hormone. Chickens fed a diet containing AA showed increased resistance to a combined Newcastle disease virus-Mycoplasma gallisepticum infection and to a secondary Escherichia coli infection, as well as to a primary E. coli challenge infection. The effects of AA and an antibacterial drug (furaltadone) were additive. In all experiments, the optimum dose of AA was 100 mg/kg of feed. There was a negative correlation between AA level in the diet and feed efficiency.     

Thermal stress on chickens in transit

1. An artificial chicken, ‘Gloria’, was constructed to simulate heat exchanges of poultry during transport. Tests of the instrument in a wind tunnel showed it to have insulation properties similar to that of a live bird.

2. Gloria accompanied chickens in two types of transport modules, A (enclosed) and B (open). The average temperature difference between inside and outside the loaded vehicles when stationary and in motion were 14.0 and 7.6 for Type A and 8.8 and 6.0 for Type B. Average air movement while vehicles were in motion was 0.5 m/s for Type A and 3.3 m/s for Type B.

3. Measurements of sensible heat loss from Gloria at different temperatures and wind speeds were compared with published estimates of thermoneutral heat production and thermal insulation for well and poorly feathered chickens to estimate the range of thermal stresses likely to be experienced by chickens in transit.

4. The results showed that the combination of circumstances necessary to ensure thermal comfort for birds both at rest and in motion is very rare (e.g. only between 7 and 8°C for well feathered birds in enclosed vehicles). It is, however, possible to ensure thermal comfort over a wide range of ambient air temperatures by appropriate control of air movement within the vehicle whether at rest or in motion.     

Effects of cage contamination with coccidia and salmonella on acute salmonellosis in young chickens

The effects of concurrent cage contamination with Salmonella typhimurium and Eimeria tenella on the establishment of salmonella infection in day-old chickens were investigated. Chickens were divided into five groups: uninfected recipient birds placed in a cage contaminated by donor birds infected with E. tenella and S. typhimurium; E. tenella-infected recipients placed in a cage contaminated by S. typhimurium-infected donors; uninfected recipients placed in a cage contaminated by S. typhimurium-infected donors; E. tenella-infected recipients placed in a cage contaminated by uninfected donors; and uninfected recipients placed in a cage contaminated by uninfected donors. Three identical trials were conducted. Recipient birds were necropsied 4, 7, and 11 days after caging. In the cage where donor birds infected with both organisms had been reared, S. typhimurium counts in feces and number of feces positive for S. typhimurium were significantly (P less than 0.05) greater than those in the other cages on days 0, 4, and 7 after caging. Moreover, in this cage, more chicks died, counts of S. typhimurium in cecal contents were greater, and more birds were positive for S. typhimurium than in the other groups. This suggests that S. typhimurium infection in day-old chickens is enhanced in cages contaminated with E. tenella and S. typhimurium compared with infection in cages contaminated with S. typhimurium alone.     

37℃持续热应激对肉鸡动脉压的影响

80羽25日龄商品代雄性AA肉鸡随机分为对照组(21℃~24℃,相对湿度50%±5%)和试验组(37℃±0.5℃,相对湿度70%±5%),动态监测各组肉鸡的股动脉压(FAP)和生产性能等指标。热暴露使肉鸡平均股动脉压、股动脉收缩压和股动脉舒张压极显著下降(P<0.01);平均股动脉压与呼吸频率、体温呈极显著负相关(P<0.01)。结果表明,37℃持续热应激使肉鸡的股动脉压极显著下降,股动脉压的变化与肉鸡对热暴露的反应和适应过程密切相关。     

铜中毒对雏鸡淋巴细胞凋亡的影响

选用1日龄艾维菌肉鸡健雏180只，随机分为3组，分别喂以对照日（Cu 11．97mg／kg）、中毒Ⅰ日（Cu 650mg／kg）和中毒Ⅱ日粮（Cu 850mg／kg），为期6周，以流式细胞术的5r法观察研究了铜中毒对雏鸡免疫器官淋巴细胞凋亡的影响。研究结果表明，铜中毒可诱导淋巴细胞凋亡，2个中毒组免疫器官淋巴细胞凋亡百分率显著高于对照组（P〈0．05或P〈0．01）。     

鸡阿奇霉素的慢性毒性实验研究

本试验采用固定剂量(1/20LD50,1/40LD50,1/80LD50)连续染毒法让大发乌骨蛋鸡120d连续摄入阿奇霉素。雏鸡生长缓慢。尸体剖检主要见肝脏体积肿大,呈黄色或浅黄色,胆囊肿大,胆汁淤滞;肠系膜点状出血。组织学变化以肝脏、肾脏、肠黏膜等组织器官的实质性细胞变性甚至坏死为特征。血液病理学变化主要是血清总蛋白含量前期降低,后期升高;白蛋白含量降低;球蛋白、总胆固醇、血糖含量和丙氨酸氨基转移酶、天门冬氨酸氨基转移酶、乳酸脱氢酶及碱性磷酸酶活性升高。     

雏鸡的饲养管理(二)

6.6科学的饲养雏鸡入舍后必须尽快学会饮水和吃食,虽然它们能够靠腹腔内保留的蛋黄在出壳后不吃不饮达三天之久,但这样会造成损害,任何延迟都会使其脱水和虚弱,从而影响雏鸡的成活率。6.6.1饮水初生雏鸡接入育雏室后,第一次饮水称为初饮。初饮应在雏鸡安置20min后立即进行,初饮时间晚会造成体内水分消耗过多,不利于雏鸡生长发育。雏鸡初次可饮5%葡萄糖水和加有抗生素、电解多维的凉开水。若是夏季经长途运输的鸡苗,最好饮给人工口服补液盐(ORS)(配方是:氯化钠2～3.5g,氯化钾1～1.5g,碳酸氢钠2～2.5g,葡萄糖20～25g,凉开水加至1000ml),可以…     

实验性雏鸡铜中毒的病理学研究

选用1日龄艾维菌肉鸡180只随机分为3组，分别以对照日粮（Cu 11．97mg／kg）、铜中毒Ⅰ组日粮（Cu 650mg／kg）和铜中毒Ⅱ组日粮（Cu 850mg／kg）饲喂6周，以实验病理学方法系统研究了铜中毒对雏鸡组织器官和某些血液指标的影响。2个铜中毒组在试验的第2、3周先后出现临床症状；铜中毒Ⅱ组雏鸡的发病率和死亡率高于铜中毒Ⅰ组。病理形态学观察，2个铜中毒组的病变基本一致，表现为肌胃角质层增厚、龟裂，肠绒毛裸露断裂，伴有坏死；肝细胞脂肪变性；肾小管上皮细胞变性，坏死脱落；淋巴免疫器官体积缩小、重量减轻、淋巴细胞数量减少。2个铜中毒组雏鸡血清谷草转氨酶（AST）活性显著升高，红细胞数量、血红蛋白含量显著降低（P〈0．05或P〈0．01）。表明，雏鸡在生长发育的2～6周对高剂量铜较为敏感，毒性损坏的靶器官是肝、肾、胃肠道和淋巴免疫器官，铜中毒导致雏鸡组织器官受损、功能障碍及免疫功能低下，最终导致发病、死亡。     

Influence of bacteria on Clostridium perfringens infections in young chickens

When monoflora chickens with Lactobacillus acidophilus or Streptococcus faecalis were inoculated with Clostridium perfringens either in broth culture or resuspended in Gifu anaerobic medium broth or supernatant fluid, few or no chickens died. Approximately 50% of germ-free chickens died after inoculation of C. perfringens culture, whereas no conventional birds died after inoculation of broth culture. C. perfringens in the contents of duodenum from germ-free chickens numbered about 10(4) colony-forming units (CFU)/g after inoculation 10(8) CFU broth culture per bird, but in gnotobiotic and conventional chickens this organism decreased or was not detected. When C. perfringens was cultured in intestinal contents collected from germ-free chickens, C. perfringens proliferated but alpha toxin was not detected. These findings indicate that the pathogenicity of C. perfringens was suppressed by L. acidophilus or S. faecalis administered previously or inhibited by normal intestinal flora.     

Clinico-haematological and mineral studies on experimental maduramicin toxicity in chickens

Clinico-haematological and mineral studies were carried out in experimental chickens given maduramicin medicated feed at 5 and 10 ppm for 21 days. Maduramicin medication in both medicated groups caused growth retardation. Clinical signs namely watery diarrhoea, depression, dullness and ruffled feathers were noticed in chickens from second week of the medication at 10 ppm but this effect was seen from third week in the birds given maduramicin at 5 ppm. Maduramicin medication caused significant reduction in haemoglobin in both the medicated group from day 14 and total erythrocyte count and packed cell volume in 10 ppm group on day 21. There was an increase in MCV in 10 ppm group on day 21 indicating macrocytic anaemia and decrease in mean corpuscular haemoglobin concentration (MCHC) in both the medicated groups indicating hypochromic anaemia. The leucopenia due to lymphopenia was observed in 10 ppm group on day 21. Maduramicin medication caused significant increase in serum Zn in 10 ppm group and decrease in Cu concentration in both the medicated groups from day 14. It is concluded that maduramicin caused toxic effects from day 14 in both the medicated groups.     

Dermal squamous cell carcinoma in young chickens

In recent years, squamous cell carcinoma in the skin of young chickens has been found more frequently at slaughter. Two nationwide surveys were completed, which verified the neoplastic classification grossly and microscopically. The deep, ulcerative lesions were found in birds from all geographic locations in the country. The medical history of the flocks was inconclusive and no site of predilection was observed. Presently, the frequency averages 2 per 10,000 birds slaughtered. The casue of this neoplastic skin condition has not been determined.