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71.
72.
Radappertized chicken drumsticks were experimentally contaminated with suspensions ofCampylobacter
jejuni in two trials. Qualitative analysis on drumsticks with an initial level of contamination of 4.8×103 CFU/cm2 showed that viability was retained for at least 10 days of storage at either 9° or –12°C.In a second quantitative trial, the level of contamination declined from 9.9×102 CFU/cm2 to 4.5×101 CFU/cm2 after 7 days at –20°C. Thereafter,C.
jejuni persisted at levels ranging from 1.8×101 to 0.2×101 CFU/cm2 through the 26th week of storage. Drumsticks held at 4°C showed a significant decline in count from 9.9×102 CFU/cm2 to 1.8×102 CFU/cm2 on day 7.It is concluded that the viability ofC.
jejuni on chicken parts is maintained under both refrigerated and freezing conditions which approximate commercial storage. This is of significance to the meat industry and consumers. 相似文献
73.
The content of heavy metals (Cd, Hg, Pb, Cr, Cu and Zn) has been determined by atomic absorption spectrophotometry in parts of genital organs of cows with and without reproductive disorders, in blood, in placenta, in colostrum, and in the calf blood. The samples were collected in an industrially polluted area and in a relatively non-polluted area. It has been proven in the group of 99 cows that the biological quality of the oestrous cervical mucus is also influenced by toxic elements. The best conception rate after the artificial insemination (80.0%) has been found in cows with the cervical mucus without spermiotoxic properties. The genital organs of 49 cows culled because of reproductive disorders were examined. No significant differences in the content of heavy metals have been found in the separate parts of genital organs. There were also no differences between the cows with and without reproductive disorders. Toxic elements in blood have been found in cows after parturition and in newborn calves both in the polluted and the non-polluted areas. However, significant differences (p less than 0.01) were determined only in the content of Cd and Zn. The average content of all determined toxic elements in the samples of placenta in pluriparous and primiparous cows from the polluted and non-polluted areas was approximately at the same level. The content of Zn was 4.3 times higher than the hygienic standard in the colostrum of cows from the polluted area. The content of Zn exceeded the hygienic standard also in the non-polluted area, and the content of Cd and Hg was close to the hygienic standard there. 相似文献
74.
75.
Perinatal exposure to atmospheric carbon monoxide at sublethal concentrations affected neonatal piglets negatively. Low total hemoglobin concentration and oxyhemoglobin saturation ratio were present at birth in piglets farrowed by gilts that had been exposed to carbon monoxide at 250 ppm from gestation d 109 on, but stillbirth rate was only 4.8%. Carboxyhemoglobin saturation ratio increased from .0 to 19.8 and 22.4% as carbon monoxide concentration rose from background (less than 5 ppm) to 200 and 250 ppm. Carbon monoxide affected neonatal piglets' behavior. Piglets exposed to atmospheric carbon monoxide at 250 ppm perinatally took longer to nurse for the first time than did counterparts under background or 200-ppm concentrations. Those under carbon monoxide at 250 ppm had compromised performance in behavior tests that measured a piglet's ability to orient itself in, maneuver in and investigate its environment, respectively. 相似文献
76.
77.
78.
A new pentacyclic triterpene, 11alpha-acetoxy-20,24-epoxy-25-hydroxy-dammar-3-one (1), has been isolated from the African tree Combretum nigricans, together with the known corresponding diol, 20,24-epoxy-11alpha, 25-dihydroxy-dammar-3-one (2). They are responsible, at least in part, for the cytotoxic activity of the methanolic extract of the plant. 相似文献
79.
Alexandre Behling Carlos Roberto Sanquetta Ana Paula Dalla Corte Sylvio Péllico Netto Aurélio Lourenço Rodrigues Bráulio Otomar Caron Augusto Arlindo Simon 《林业研究》2016,27(6):1211-1217
The amount of photosynthetic radiation intercepted by a crop is a function of the incident solar radiation on the plants, the leaf area index (L AI), and the light extinction coefficient (k). We quantified L AI and k in stands of black wattle (Acacia mearnsii De Wild.) over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. L AI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer’s law. L AI depends on the planting site and stand age. Between the two sites, the L AI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to L AI and was correlated with L AI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter. 相似文献
80.
This research examined the first year growth characteristics of cold stored and transplanted nursery-produced aspen (Populus tremuloides) seedlings (container and bareroot (BR)) and compared it to the growth of seedlings that had not been transplanted (established
from germinants in the field) and therefore had an unrestricted root system (UR). Prior to planting, nursery-produced seedlings
were placed in cold storage (−3°C) and root growth potential (RGP) and total non-structural carbohydrate (TNC) root reserves
were tested at 0, 10, 75 and after 150 (container) and 190 days (BR) of storage. Both container and BR stock had much lower
root to shoot ratios (RSRs) and root carbohydrate reserves compared to UR seedlings after 170 days. During storage, root reserves
in container stock declined faster than in the BR and UR seedlings. RGP in all nursery stock was the highest after 75 days
of storage, while longer storage resulted in shoot dieback and reduced root growth. After the first growing season, UR seedlings
were one tenth the size of the nursery stock; however, in the second growing season they had no stem dieback and grew twice
the height and stem diameter. The higher RSRs and root reserves in the UR seedlings was likely caused by early bud set in
its first year of growth. This suggests that inducing bud set earlier in the growing regime might allow seedlings to increase
root mass and carbohydrate reserves. 相似文献