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排序方式: 共有1419条查询结果,搜索用时 15 毫秒
991.
992.
Brown Swiss-Hereford (BS-H) reciprocal cross embryos were transferred to BS and H recipient cows and Red Poll-Angus (RP-A) reciprocal cross embryos were transferred to RP and A recipient cows to estimate the relative contributions of ovum cytoplasm and uterine influences to prenatal maternal effects. Calves resulting from embryo transfers (ET) were weaned early (3 to 5 d). Reciprocal cross mating also were made by natural service (NS) between BS and H and between RP and A breeds; part of the offspring were weaned at 3 to 5 d, and the remainder nursed their dams to an age of 150 to 180 d. This was done to estimate breed differences in prenatal and postnatal effects combined and to separate the effects of prenatal maternal influences from postnatal maternal influences of these breeds. Females produced in both ET and NS parts of the experiment were retained to produce three calf crops to an age of about 4.5 yr. The following traits were analyzed: percentage of conception rate; percentage of calf survival; percentage of calves produced per cow exposed; birth and weaning weights of calves produced; and periodic weights, heights, and condition scores of females to an age of 4.5 yr. Neither breed of donor (cytoplasmic influence) nor breed of recipient (uterine influence) had consistently important effects on the traits evaluated. In NS matings, differences between reciprocal crosses were small for most of the traits evaluated. Method of rearing (nursed vs weaned at 3 to 5 d) had no effect on reproductive and maternal traits for RP-A reciprocal cross females, but females that nursed generally were heavier, were taller, and had higher condition scores at most ages than early-weaned females. For the BS-H reciprocal cross, early-weaned females were favored over females reared by their dams in percentage of calves produced per cow exposed, but the method of rearing did not affect other reproductive or maternal traits. BS-H reciprocal cross females that nursed their dams were heavier at 550 d and were heavier and had higher condition scores at an age of 34 mo than early-weaned females. 相似文献
993.
David S. Biller DVM Gregory A. Bradley DVM Beth P. Partington DVM MS 《Veterinary radiology & ultrasound》1992,33(5):286-290
An echogenic line in the outer zone of the renal medulla, paralleling the corticomedullary junction is described as the renal medullary rim sign. This renal ultrasonographic change is demonstrated in 4 dogs and 2 cats with a range of renal diseases. The renal medullary rim sign provides additional ultrasonographic criteria indicating primary renal disease in some patients. However the renal medullary rim sign may prove to be a poor correlate for prognosis across the range of differentials present in these clinical patients. 相似文献
994.
Ten ducks were subjected to electrical stunning with their heads completely immersed in the water of a waterbath, and 10 ducks received the same current while only the bill and skin over the crop made contact with the water. The effect on visual evoked responses in the brain was examined. A higher proportion of birds had lost their visual evoked responses immediately following the current with whole head immersion. It is suggested that crop and bill immersion is less effective in disturbing brain function than whole head immersion. 相似文献
995.
Rhea V. Morgan DVM Robert L. Donnell DVM Gregory B. Daniel DVM MS 《Veterinary radiology & ultrasound》1994,35(5):362-367
Magnetic resonance images of a screech owl ( Otus asio ) were acquired to identify the normal anatomic components of the eye'and orbit. T1-weighted, proton-density, and T2-weighted images were obtained in the straight sagittal, oblique dorsal, and oblique sagittal planes. Signal intensity for the various orbital structures differed between the three resonance techniques. T1-weighted images provided the best anatomic detail of ocular and orbital structures. The oblique dorsal and oblique sagittal planes were superior for evaluating the optic nerve in its entirety. 相似文献
996.
997.
G. G. Gregory B.V.Sc. B. L. Munday M.V.Sc. M.A.C.V.Sc. 《Australian veterinary journal》1976,52(7):317-320
998.
Tuberculosis in captive seals: bacteriological studies on an isolate belonging to the Mycobacterium tuberculosis complex 总被引:3,自引:0,他引:3
D V Cousins B R Francis B L Gow D M Collins C H McGlashan A Gregory R M Mackenzie 《Research in veterinary science》1990,48(2):196-200
Culture of tuberculous lesions from six of 14 captive seals yielded an organism which, on the basis of biochemical and drug sensitivity tests, was identified as Mycobacterium bovis, although the organism showed a weak cording pattern and was glycerol tolerant. It was pathogenic in rabbits and guinea pigs and after passage the organism exhibited strong cord formation and was glycerol intolerant. Restriction endonuclease analysis and sodium dodecyl-sulphate polyacrylamide gel electrophoresis indicated that the organism belonged to the Mycobacterium tuberculosis complex. Restriction patterns indicated that infection in the six seals was from a single source. Western blotting with monoclonal antibody to M bovis identified antigens at 23 and 27 kDa in M bovis which were absent from the seal isolates. 相似文献
999.
Twinning in cattle: I. Foundation animals and genetic and environmental effects on twinning rate 总被引:3,自引:0,他引:3
K E Gregory S E Echternkamp G E Dickerson L V Cundiff R M Koch L D Van Vleck 《Journal of animal science》1990,68(7):1867-1876
Foundation cows were selected using prior records from one of two sources, private herds or other projects at the Research Center. Comparing twinning rates before and after selection, the repeatability was lower for those from the first (.08) than for those from the second (.16) source with a combined value of .12. Realized heritability of single-parity twinning rate estimated from selection of parents and response in daughters of foundation females was .06. Paternal half-sib estimate of heritability of twinning rate was .02 +/- .07. Estimates of repeatability computed from calving records of females born in the project indicate that permanent environmental effects on twinning rate in cattle are small. Mean calving rate of females born in the project was 1.11 in the data set that included all data and 1.09 in the data set that excluded females from highly selected parents. Twinning rate was greater (P less than .05) in fall than in spring calving (1.13 vs 1.06). Data on twinning rate of a sample of the Swedish Friesian breed were summarized. Mean twinning rate of the Swedish Friesian breed is 2.57%. Age adjusted mean twinning rate of daughters of 32 half-sib sons of one particular Swedish Frieisan sire averaged 5.4% and ranged from .9% to 13.6%. There was no indication of a bimodal distribution, which would be expected if a single gene with a major effect on twinning rate were segregating. The estimated genetic standard deviation (sigma-xn) for mean twinning rates of the 32 sire progeny groups was 1.8%. Observed range among son progenies was .127 or 7.2 sigma-xn, in reasonable agreement with the hypothesis that twinning rate in this population is inherited as a quantitative trait. 相似文献
1000.
Paul R. Bowser Gregory A. Wooster Anita L. Aluisio Julia T. Blue 《Journal of the World Aquaculture Society》1989,20(4):173-180
Plasma chemistries were measured in Atlantic salmon ( Salmo salar ) exposed to elevated nitrite concentrations in an attempt to identify those parameters of potential value as early predictors of nitrite stress in a water-reuse system. The most notable finding was a decrease in alkaline phosphatase (ALP) activity with increasing time of exposure to elevated nitrite concentrations. Chloride was found to have a protective effect against nitrite toxicity as indicated by higher ALP activities and lower percent methemoglobin in fish exposed to elevated nitrite concentrations at the higher of two chloride concentrations. 相似文献