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101.
Information in the literature indicates that young ostrich chicks, despite being precocial, are poor thermoregulators and may take between 8 and 12 weeks to develop efficient homeothermy. We measured the body temperatures (Tb) of young ostrich chicks (1 to 10 d) at ambient temperatures between 13 degrees and 28 degrees C under controlled conditions in the laboratory and under typical farm-rearing conditions to assess their ability to thermoregulate. Even 1-d-old ostriches could maintain a Tb above 36 degrees C at temperatures of 20 degrees C and older chicks maintained typical adult Tb at ambient temperatures of 13 degrees C in a constant temperature room. Chicks from 2-d-old could maintain adult T(b)s outdoors under a wide range of ambient temperatures and weather conditions. We conclude that ostrich chicks have well developed homeothermy soon after hatching and that some of the higher rearing temperatures recommended in the literature are unnecessary. In appropriate climates, chicks can be allowed outdoors soon after hatching provided they are not exposed to unfavourable weather conditions. Thermoregulation is, however, energetically expensive and thermoregulatory behaviour such as huddling may compete with other important activities like feeding. 相似文献
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The effects of different doses and dosage regimens on gentamicin pharmacokinetics and tissue residues were determined. Five groups of 12 sheep each were given gentamicin IM: group I, 2 mg of gentamicin sulfate/kg once; group II, 6 mg/kg once; group III, 18 mg/kg once; group IV, 6 mg/kg every 24 hours for 3 doses; and group V, 2 mg/kg every 8 hours for 9 doses. Serum concentrations were determined serially until sheep were killed and necropsied. Three sheep from each group were killed at 1, 4, 8, and 12 days after the last dose was administered. Renal cortex, renal medulla, liver, spleen, lung, skeletal muscle, and skeletal muscle at the injection site were assayed for gentamicin. An exponential equation was fitted to the serum concentrations, and various pharmacokinetic variables were determined. Serum clearance tended to increase as the single dose increased (P = 0.0588). Steady-state volume of distribution increased as the single dose was increased (P less than 0.05). Renal cortex contained the highest concentration of gentamicin which decreased in a biexponential manner. Concentrations in all tissues, except the injection site, were dependent upon the amount of the total dose, not the size of the injected dose (P less than 0.05). Concentrations at the injection site were up to 29 micrograms/g of tissue at 1 day after the last dose was given and were dependent upon the amount of total dose from multiple injections, not on the amount of each injected dose (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
104.
The present study was conducted to determine whether a marginal Se deficiency affects health, blood characteristics and the immune response of calves subjected to stresses associated with weaning, shipping (332 km) and Pasteurella hemolytica inoculation. Treatments were 1) -Se, 2) -Se/P. hemolytica, 3) +Se (.1 mg Se/kg feed) and 4) +Se/P. hemolytica. Previous Se intake was controlled; dams of -Se calves were fed diets marginally deficient in Se (.03 to .05 mg/kg), whereas dams of +Se calves received a s.c. injection of 30 mg Se (as sodium selenite) every 60 d. Calves were inoculated with P. hemolytica intratracheally on d 3 following weaning and transport. Inoculation with P. hemolytica increased (P less than .05) body temperatures, platelet counts, serum IgM concentrations and serum antibody titers and decreased serum albumin concentrations at 4 to 7 d postinoculation. Weight gains for the 21-d study were not affected by Se status, although whole blood and plasma glutathione peroxidase (GSH-Px) were higher (P less than .05) for +Se calves. Plasma GSH-Px increased (P less than .01) in calves showing signs of morbidity. Increases in plasma GSH-Px were correlated positively with body temperature. Serum IgM concentrations were higher (P less than .05) in +Se calves on d 17, but Se-supplemented calves had lower (P less than .05) anti-P. hemolytica titers on d 17 than -Se calves. Selenium status did not affect body temperatures, plasma creatine phosphokinase or serum IgG and albumin concentrations. These results indicate that Se status can affect IgM concentrations following stress. 相似文献
105.
The effect of dose and line on immunisation of cattle with lymphoblastoid cells infected with Theileria annulata 总被引:1,自引:0,他引:1
H Ouhelli E A Innes C G Brown A R Walker S P Simpson R L Spooner 《Veterinary parasitology》1989,31(3-4):217-228
Thirty-one Friesian calves in Morocco susceptible to tropical theileriosis were protected against a lethal sporozoite challenge by prior infection with lymphoblastoid cell lines infected and transformed in vitro by a Moroccan stock of Theileria annulata. The challenge infection of cryopreserved sporozoites killed all four susceptible control calves within 20 days. Four schizont-infected cell cultures at Passage 3 were inoculated at four different doses, 10(8), 10(6), 10(4) and 10(2), into pairs of calves. The recipient animals showed great variation in severity of disease symptoms, which did not show a linear correlation with the cell dose inoculated. The most severe disease symptoms were recorded, prior to challenge, in the 10(2) cell dose recipients; one animal died of acute theileriosis and another had to be treated. One of the four cell lines used was more virulent than the other three. Two years after the completion of this experiment, immunised animals have shown normal productivity traits. 相似文献
106.
Significance of ureaplasma infection in infertility of turkeys 总被引:4,自引:0,他引:4
L Stipkovits P A Brown R Glavits J Zajer 《Archiv fuer experimentelle veterinaermedizin》1986,40(1):103-104
107.
The use of polyester fibers has grown more rapidly than that of any other man-made fiber. Many factors have contributed to this growth. Polyester's unique physical properties of strength, high modulus, elasticity, and durability are the basis for its success. The tailorability of the fiber makes it possible to generate a whole family of property variants for a wide variety of end uses. The ready availability and low cost of the raw materials, the continuing advances in polymerization technology, and the versatility of the melt spinning process have also been major factors in establishing polyester as the leading man-made fiber. New end uses have had a major impact on the growth of polyester. Most notable was the introduction of durable press fabrics for clothing and home furnishings. The consumer preference for easy-care fabrics and garments makes the durable press area one of continuing growth. Two relatively new areas where growth is expected to continue at a rapid rate are tire cord and textured knits for women's and men's outerwear. 相似文献
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Methyl bromide, used at a concentration‐time product of 800 mg h/l at 25 °C with a relative humidity of 70%, was successful in eliminating salmonellae from artificially contaminated poultry foodstuffs. Chicks fed on this fumigated food remained free from the infection and there were no adverse effects on growth rate. 相似文献