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131.
D D 《Science (New York, N.Y.)》1988,240(4860):1728
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Kevles DJ 《Science (New York, N.Y.)》1988,242(4883):1314-1315
135.
Dickson D 《Science (New York, N.Y.)》1988,239(4841):720-721
136.
Dickson D 《Science (New York, N.Y.)》1988,242(4884):1375-1376
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138.
In a balance trial with 10 pigs (mean body mass 50 kg) the influence of a bacterial protein supplement (Alcaligenes eutrophus) on N-metabolism was investigated. The bacteria were included into the diet at levels of 7 and 14% at the expense of extracted soyabean meal. Thus bacterial "pure protein" (bacterial non-nucleic acid N X X 6.25) amounted to 30 and 60% of the protein of the ration. Consuming 2 kg of feed dry matter per day the animals of the control group (I) and the experimental groups (II and III) ingested 48 g, 52 g and 55 g of total N respectively. The difference in N-intake is explained by the additional nucleic acid-N, amounting to 19,8% of total bacterial N. Daily weight gain (on average 1054 g) and feed conversion efficiency (feed ingested/weight gain; on average 1,9) were relatively improved at the highest dietary level of bacterial cell mass. Faecal N-excretion was increased significantly, whereas renal N-excretion remained unchanged. Mean apparent N-digestibility was 87,4% showing no significant difference between the experimental groups. N-balance values were noticibly increased following the intake of the bacterial protein supplement. The excretion of urinary urea-N was slightly reduced whereas 4-6 times as much allantoin-N was excreted when bacteria were fed. It is calculated that about 80% of the bacterial purines are renally excreted as allantoin and uric acid. 相似文献
139.
The influence of genotypic differences in resistance to infection from Lymphoid Leukosis (LL) on mortality and egg production was studied in three pairs of sublines. One subline of each pair had been selected for resistance and the other for susceptibility to infection. At 10 months of age, almost no hens with neutralising antibodies against LL were found in the resistant sublines, while in each susceptible subline more than 40% of the hens had LL antibodies. At 21 months of age, very few hens of the resistant sublines had group-specific (gs) antigen in their eggs. Susceptible sublines differed considerably in this respect, from 81% gs antigen-positive hens in one subline to 9% or no positive hens in the others. On the whole, the susceptible sublines had 6% higher mortality during the laying period (8 months) but the size of the difference was influenced by vaccination against Marek's disease (MD) and varied considerably between pairs of sublines. Significant interactions between strain and genotype of resistance to LL infection were observed for mortality from "other causes" in hens vaccinated against MD, as well as for mortality from "Leukosis" and from "MD" in non-vaccinated hens. The average rate of lay from 1 to 8 months was 8% lower in susceptible hens. In the subline with the highest frequency of eggs containing LL group-specific antigen in the albumen, the reduction of laying rate was twice as large as in the other susceptible sublines. 相似文献
140.