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1.
An experiment was conducted on 30 male Nellore lambs with average body weight (BW) of 15.45 +/- 0.06 kg to determine the level of the copper (Cu) supplementation in diet from inorganic and organic sources required for optimum immunity and its effect on copper dependent enzymes by allotting them randomly to five groups in completely randomized design. The dietary treatments were viz., basal diet (no Cu supplementation, BD), other four groups were offered BD supplemented with 7 or 14 ppm Cu from copper sulphate (CuSO(4)) and Cu-proteinate, respectively. The lambs were fed the respective diets at 3.5 per cent BW to meet the requirements except Cu for 180 days. The humoral immune response against Brucella abortus and chicken RBC was assessed after 90 days of feeding. The in vivo delayed type hyper sensitivity reaction against PHA-P and in vitro lymphocyte proliferation against Con A indicative of cell mediated immune response (CMI) was assayed at 180 days of feeding. At the end of experiment four lambs from each group were slaughtered for estimation of liver superoxide dismutase activity (SOD). The ceruloplasmin and RBC-SOD activities were higher (P < 0.05) in 14 ppm Cu supplemented lambs from Cu-proteinate at 90 and 180 days, while the liver SOD activity was higher (P < 0.05) in lambs fed 14 ppm Cu from CuSO(4). The STAT titres against B. abortus were higher in Cu supplemented lambs, with no effect of dose of supplementation. Lambs supplemented with Cu-proteinate had higher titers than CuSO(4) on 7 and 14 days of post sensitization. The total immunoglobulin concentration and the CMI response against PHA-P and Con-A was higher (P < 0.05) in lambs fed 14 ppm Cu-proteinae diet. The IgM level was though high in Cu supplemented lambs, no dose or source effect were observed. The study indicated that Cu dependent enzymes activity and immune response were highest and respond better against stress in lambs on 14 ppm supplemented Cu from Cu-proteinate.  相似文献   

2.
Diets containing 3% sorghum ergot (16 mg alkaloids/kg, including 14 mg dihydroergosine/kg) were fed to 12 sows from 14 days post‐farrowing until weaning 14 days later, and their performance was compared with that of 10 control sows. Ergot‐fed sows displayed a smaller weight loss during lactation of 24 kg/head vs. 29 kg/head in control sows (p > 0.05) despite feed consumption being less (61 kg/head total feed intake vs. 73 kg/head by control sows; p < 0.05). Ergot‐fed sows had poorer weight gain of litters over the 14‐day period (16.6 kg/litter vs. 28.3 kg/litter for controls; p < 0.05) despite an increase in consumption of creep feed by the piglets from the ergot‐fed sows (1.9 kg/litter compared with 1.1 kg/litter by the control; p > 0.05). Sow plasma prolactin was reduced with ergot feeding after 7 days to 4.8 μg/l compared with 15.1 μg/l in the control sows (p < 0.01) and then at weaning was 4.9 μg/l compared with 8.0 μg/l (p < 0.01) in the control sows. Two sows fed ergot ceased lactation early, and the above sow feed intakes, body weight losses with litter weight gains and creep consumption indirectly indicate an ergot effect on milk production.  相似文献   

3.
Nutritional and toxicologic feeding trials with 3 species of farm animals demonstrated that decreased feed consumption and reduced weight gains in pigs are the main effects of ingestion of a diet with low vomitoxin (deoxynivalenol; DON) content, eg, 2 mg of DON/kg of feed, ie, 2 ppm. The feeding trials indicated that swine can ingest up to 2 mg of DON/kg of feed without serious adverse effects. Poultry can tolerate at least 5 mg of DON/kg feed. In fact, at concentrations up to 5 mg of DON/kg feed, some beneficial effects on poultry were observed. In dairy cattle, feed consumption decreased slightly when a wheat-oats diet containing 6 mg of DON/kg was fed at the rate of 1% of body weight/day, with hay offered ad libitum. In surveys of Canadian grains carried out during the past 3 years, the DON content (maximum of 8.5 mg/kg) in eastern Canadian wheats probably was not high enough to account for reports of feed refusal, vomiting, and reproductive problems in livestock operations. This conclusion is based partly on the fact that even at the highest concentrations of DON found in wheat, formulated diets comprise, at maximum, about 70% to 80% wheat. Consequently, the actual DON content of diets fed to farm animals would be much lower.  相似文献   

4.
Thirty-two boars were fed diets containing 0, 3, 6 or 9 ppm zearalenone from 32 d of age up to 145 or 312 d of age. Rate of gain, feed intake and gain:feed were not significantly different among treatments. Feeding of diets containing 9 ppm zearalenone did not affect the libido in seven boars. There was a tendency for boars fed 9 ppm dietary zearalenone to produce lower total and gel free volumes of semen, with lower total motile sperm; however, only the percent motility of the sperm was reduced (P less than .05).  相似文献   

5.
Four groups of mycoplasma-free commercial broilers were challenged with the R strain of Mycoplasma gallisepticum (MG) at 14 days of age. Groups received feed containing either no medication, or 500 ppm or 1000 ppm oxytetracycline (OTC) beginning at age 13 days, or 1000 ppm OTC beginning at age 15 days. All broilers were vaccinated with a live mild Massachusetts infectious bronchitis vaccine at 17 days of age. Air sac lesions were scored at age 24 days. In two almost identical experiments, all OTC treatment groups had significantly lower mean air sac lesion scores than the unmedicated challenged controls. Groups that were fed 1000 ppm OTC in feed had significantly lower mean air sac lesion scores than groups that were fed 500 ppm OTC in feed. There was no significant difference in mean air sac lesion scores between the groups fed 1000 ppm OTC in feed beginning at 13 days of age and those fed 1000 ppm OTC in feed beginning at 15 days of age.  相似文献   

6.
采用低温诱发肉鸡肺动脉高压综合征,对比观察不同的早期限饲方法对于常温和低温条件下PHS的发病率、肉鸡生产性能和腹脂率的影响。在试验1中,限饲处理组肉鸡分别于7￣14日龄或7￣21日龄每天给料8h,对照组肉鸡全程自由采食。在试验2中,限饲组肉鸡分别于7￣14日龄给予对照组肉鸡前1d饲料消耗量的60%或80%。结果表明:早期限饲能够降低肉鸡PHS的发病率,在低温条件下尤其明显;早期限饲改善了饲料效率,同时未对肉鸡的胴体品质产生显著的影响,且适当限饲不影响肉鸡的最终上市体重。这表明早期限饲是一种有效的控制肉鸡PHS的方法,值得在实际生产中推广应用。  相似文献   

7.
In May 1996, 150 grower pigs in 5 California counties were exposed to selenium-contaminated feed distributed by a single feed company. Feed samples from 20 herds had a mean selenium concentration of 121.7 ppm dry weight (range, 22.1-531 ppm). In San Luis Obispo County, 52 pigs in 24 herds were exposed to the feed, and 8 pigs died with signs of paralysis. Bilateral symmetrical poliomyelomalacia involving the ventral horns of the cervical and lumbar intumescence was evident on histologic examination of spinal cord from affected pigs. Of 44 surviving exposed pigs, 33 (75%) exhibited signs of selenosis, including anorexia, alopecia, and hoof lesions. Thirty-nine of 44 pigs (88.6%) had elevated (>1 ppm) blood selenium concentrations. Surviving exposed pigs were changed to a standard commercial ration containing approximately 0.5 ppm (dry weight) selenium. Blood selenium concentrations were determined weekly for 46 days following removal of the contaminated feed and were compared with values of 20 control pigs fed a standard commercial ration. Mean (+/-SD) blood selenium concentrations of exposed pigs were 3.2 +/- 2.6 ppm at the initial sampling and 0.4 +/- 0.1 ppm after 46 days. Mean blood selenium concentrations of < or = 0.3 ppm for control pigs at all samplings were significantly lower (P < 0.001) than concentrations for exposed pigs. Muscle and liver samples of 22 of the 44 exposed pigs were collected at slaughter approximately 72 days after withdrawal of the selenium-contaminated feed. Muscle samples had a mean selenium concentration of 0.36 ppm (wet weight). Liver samples had a mean selenium concentration of 1.26 ppm (wet weight). One liver sample had a selenium value in the toxic range for pigs (3.3 ppm wet weight; reference range, 0.4-1.2 ppm). A 1-compartment pharmacokinetic model of selenium elimination in exposed pigs was generated, and the geometric mean blood selenium elimination half-life was estimated to be 12 days. The 60-day withdrawal time recommended by the Food Animal Residue Avoidance Database was considered sufficient to allow safe human consumption of tissues from exposed pigs.  相似文献   

8.
Nine experiments were conducted at three stations to evaluate the efficacy of furazolidone as a growth promoter in diets for young swine and to determine if an early growth response is maintained after the additive is withdrawn from the diet. A total of 528 pigs (24 replications, 132 pigs/treatment) initially averaging 12 kg body weight were fed a nonmedicated basal diet or a diet with 110 ppm furazolidone for 5 wk, 165 ppm furazolidone for 3 wk or 220 ppm furazolidone for 2 wk. After withdrawal of furazolidone, the basal diet was fed to the end of the test, at which time the pigs averaged 93 kg. During the initial 2-wk period, pigs fed furazolidone gained 15.4% faster (P less than .001) and required 8% less (P less than .001) feed per unit of gain than control pigs fed the nonmedicated diet. At 5 wk, pigs previously fed furazolidone gained 8.4% faster (P less than .001) and 4.5% more efficiently (P less than .001) than controls. By 10 wk, pigs previously fed furazolidone maintained a slight advantage in growth rate over controls (2.6%, P less than .10), but feed/gain responses were similar for the two groups. By the end of the experiment, the early growth response from furazolidone was completely lost. Although there were differences in growth responses among stations, the treatment response patterns were similar for each station, with no evidence of a treatment X station interaction.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
In 2 studies, the effects of dietary aflatoxin (AF) and deoxynivalenol (DON) were evaluated in growing crossbred barrows. The first study consisted of 4 treatments of 5 barrows each (6 weeks old) at dosages of 0 mg of DON and AF (control), 2.5 mg of DON/kg of feed, 0.75 mg of AF/kg of feed, and 2.5 mg of DON + 0.75 mg of AF/kg of feed. Pigs were fed their respective diets for 21 days. Treatment with DON caused decreases in weight gains, but no other treatment-related differences could be attributed to diets. In a second study, the experimental design consisted of 4 treatments of 5 barrows each (6 weeks old) at dosages of 0 mg of DON and AF (control), 3 mg of DON/kg of feed, 3 mg of AF/kg of feed, and 3 mg of DON + 3 mg of AF/kg of feed fed ad libitum for 28 days. The pigs were observed twice daily for clinical signs, hematologic and serum biochemical measurements were made weekly, and body weights and feed consumption were determined weekly. Body weight gains were significantly depressed by the AF and the AF + DON treatments for days 7, 14, 21, and 28. Body weights and body weight gains were only slightly reduced in the DON treatment. Changes in serum enzymatic activities of alkaline phosphatase, aspartate transaminase, creatine kinase, and gamma-glutamyl transferase were noticed in pigs given treatments with AF alone and those given AF + DON.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
The prevalence of deoxynivalenol (DON) is a concern for swine producers, and although there has been extensive research into the effects of DON in pigs, focus has been in young pigs and/or in short-term studies. The objective of the study was to determine the effect of long-term exposure to DON-contaminated diets in finisher pigs. A total of 200 pigs (76.6 ± 3.9 kg initial weight) were group housed (five pigs per pen; n = 10 pens/treatment) in a 6-wk trial. Pigs were fed a wheat-barley-soybean meal-based control (CONT) diet with no DON or the basal diet in which clean wheat was replaced by DON-contaminated wheat and wheat screenings to provide DON content of 1, 3, or 5 ppm (DON1, DON3, and DON5, respectively). Individual BW and pen feed intake were recorded weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Blood was collected on days 0, 14, and 43 and analyzed for indicators of liver and kidney health. Nitrogen (N)-balance was conducted immediately following the growth performance period to determine the effect of DON on nutrient utilization. Blood and urine samples collected during N balance were analyzed for DON content. Feeding DON reduced (P < 0.05) ADFI and ADG from days 0 to 28 compared with CONT, after which there was no effect of diet on ADFI and ADG. The G:F was lower (P < 0.05) in DON5 fed pigs compared with all treatments during days 0 to 7; however, no treatment effects on G:F was observed from days 8 to 42. Nitrogen retention was lower (P < 0.05) in DON3 and DON5 compared with DON1-fed pigs. Nitrogen retention efficiency was higher (P < 0.05) in DON1 compared with DON3 and DON5 and protein deposition for DON1 pigs was higher (P < 0.05) than all treatments. There were no treatment effects on indicators of liver and kidney health. As dietary DON intake increased, concentration of DON in blood and urine increased. Overall, although there was an initial decrease in ADG and ADFI in pigs receiving diets containing >1 ppm DON, pig performance recovered after a period of time, whereas nutrient utilization continued to be affected after recovery of performance. Moreover, the lack of DON on G:F indicates that the negative effects of DON on growth performance are largely due to reduced feed intake. Overall, although pigs maybe capable of adapting to intake of DON-contaminated diets, their final body weight will be reduced when fed diets containing >1 ppm DON.  相似文献   

11.
Male mice selected for rapid 3 to 6 wk postweaning gain (M16) and unselected controls (ICR) were ad libitum fed a stock diet containing 0, 50 or 200 ppm cimaterol, a beta-agonist, from 4 to 7 or 4 to 10 wk of age. Mortality rate was higher in M16 than in ICR mice fed cimaterol (12.5 vs 1.3%; P less than .01). No mortalities occurred in either line fed the control diet. Line M16 exceeded (P less than .01) ICR in growth rate, feed intake, feed efficiency and lean index. Line X cimaterol level interactions (P less than .01) were found for the first three of these traits, although cimaterol level did not change line ranking. Epididymal fat as a percentage of empty body weight decreased at a faster rate in M16 than in ICR as cimaterol level increased. At 0 and 50 ppm, M16 exceeded ICR (P less than .05), but at 200 ppm there was no line difference (P greater than .05). Line M16 exceeded (P less than .05) ICR in blood glucose (5%), nonesterified fatty acids (4%) and lactate at 7 wk (9%), but lactate was higher in ICR at 10 wk (13%). Lines were not different in blood urea-N. Compared to zero cimaterol level, at 50 and 220 ppm glucose decreased (14% and 23%; P less than .05), nonesterified fatty acids decreased (3% and 29%; P less than .05), lactate increased (9% and 11%; P less than .05) and blood urea-N increased (3% and 16%; P less than .05). There were no line X cimaterol level interactions for blood metabolites. Differences in mortality rate, growth, feed consumption, feed efficiency and epididymal fat pad percentage between the high-growth and control lines in response to cimaterol may reflect genetic differences in mechanisms of metabolic regulation.  相似文献   

12.
1. The effects of dietary supplementation of a commercial probiotic (Protexin) on daily feed consumption, egg yield, egg weight, food conversion ratio and humoral immune response in layer hens were investigated. In 7 replicates, a total of 280 40-week-old layers were given diets containing either 0, 250, 500 or 750 parts per million (ppm) for 90 d. 2. When compared with the controls, the food consumption, food conversion ratio and the proportions of damaged eggs were lower in the group consuming 500 ppm probiotic (P<0.05). 3. There was no significant difference between the controls and the groups receiving 250 and 750 ppm probiotic in food consumption, food conversion ratio and proportion of damaged eggs. Similarly, the egg yield, egg weight, specific gravity, and peripheral immune response showed no statistically significant differences between the groups.  相似文献   

13.
The ability of activated charcoal to adsorb ochratoxin A (OA) in vitro and to reduce the toxic effects of OA in vivo when added to the diet of growing Leghorn chicks was studied. Activated charcoal (50 mg) was able to adsorb 90% of the OA (150 micrograms) contained in 10 mL of citrate-phosphate buffer (pH 7.0). When 2 g of a complete chick diet were mixed with OA in buffer, it adsorbed 66% of the OA, while addition of 50 mg of charcoal to this mixture further reduced the concentration of OA to 11.8% of the control, an additional 65% compared to the diet alone. In the first of two feeding studies, charcoal addition of up to 10,000 parts per million (ppm) to diets (6.7% tallow) containing 9.93 mumol (4 ppm) OA kg-1 diet had no effect on OA toxicity. Feed consumption and weight gain, however, were reduced 10 and 20%, respectively, in chicks fed diets which contained 10,000 ppm of charcoal compared to those fed no charcoal. In the second study, reducing dietary tallow to 2% did not alter the effects of OA or charcoal on weight gain and feed to gain ratio, but birds fed OA with 10,000 ppm charcoal had an 8.5% increase in feed consumption. An additional management problem was associated with the propensity of charcoal to blacken the feed, the birds and their environment. Addition of charcoal to OA contaminated diets appeared to be an ineffective method for reducing the toxic effects of OA in growing chicks.  相似文献   

14.
The effect of T-2 toxin (trichothecene mycotoxin) consumption on Broad-Breasted White turkey poults and White Leghorn chicks was studied. Groups of ten 8-day-old poults were fed rations containing T-2 at 10 ppm, 2ppm, or 0 ppm (controls) for a period of 4 weeks; a 4th group (inanition control) was fed control rations equal to the amount consumed by the group fed rations containing T-2 at 10 ppm during the previous 24 hours. A similar experimental design was used to study the effect of the toxin on 1-day-old chicks. The thymus glands of the poults given the feed containing 10 ppm were markedly decreased in size compared with thymus glands from poults in the control group, 0.182 vs 0.331 (percentage of body weight). There was no significant (P less than or equal to 0.05) decrease in thymus gland size in poults given 2 ppm or in the inanition controls. Dietary treatment did not appear to affect the size of the bursa or spleen of the poults. Histopathologic examination of thymus glands from poults given 10 ppm of T-2 revealed a depletion of cortical lymphocytes. Chicks appeared less sensitive to T-2 toxin than did the poults. There was no effect by any dietary treatment on the size of the thymus gland, bursa, or spleen of chicks. Reductions were noticed in feed efficiency and weight gain. There was no effect of T-2 toxin on agglutinating antibody formation to Pasteurella multocida bacterin.  相似文献   

15.
A total of 72 pigs weaned at 4 wk of age were allotted by litter and weight to nine treatment groups and fed 20% protein cornsoybean meal diets supplemented with various levels of inorganic Se during a 37-d postweaning period. Eight groups were fed diets with 0, 2.5, 5.0, 7.5, 10, 15, 20 or 40 ppm Se provided as sodium selenite, while a ninth was offered the 0- and 40-ppm Se diets in separate feeders. Gains and feed intakes were similar during the trial for the 0- and 2.5-ppm Se diets. Both gain and feed intake declined as dietary Se levels above 5.0 ppm increased. At a dietary Se concentration of 40 ppm, feed consumption ceased within a few days of feeding and subsequent gains were negative. Pigs offered both the 0- and 40-ppm Se diets preferentially selected the basal as compared with the 40-ppm Se diet. When the feeders were switched at 28 d they refused the 40-ppm Se diet within a few hours. After a 17-d period, pigs fed the 20- or 40-ppm Se diet were not able to coordinate their walk, with many exhibiting an inability to stand. Alopecia was demonstrated in pigs fed 15 ppm Se or higher at 17 d, but was evident in the 5.0-ppm group at 37 d. At the termination of the trial, abnormal hoof formation at the coronary band was evident in pigs fed diets containing Se greater than or equal to 5 ppm.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

16.
Milk residues and performance were evaluated in lactating cows that were fed up to 10 times the recommended dose of monensin. Following an acclimatization period of 14 d, during which cows were fed a standard lactating cow total mixed ration containing 24 ppm monensin, 18 lactating Holstein dairy cows were grouped according to the level of feed intake and then randomly assigned within each group to 1 of 3 challenge rations delivering 72, 144, and 240 ppm monensin. Outcome measurements included individual cow daily feed intakes, daily milk production, body weights, and monensin residues in composite milk samples from each cow. There were no detectable monensin residues (< 0.005 microg/mL) in any of the milk samples collected. Lactating cows receiving a dose of 72 ppm monensin exhibited up to a 20% reduction in dry matter intake, and a 5% to 15% drop in milk production from the pre-challenge period. Cows receiving doses of 144 and 240 ppm monensin exhibited rapid decreases in feed intake of up to 50% by the 2nd d and milk production losses of up to 20% and 30%, respectively, within 4 d. Lactating cows receiving up to 4865 mg monensin per day had no detectable monensin residues (< 0.005 microg/mL) in any of the milk samples collected. Results of this study confirm that food products derived from lactating dairy cattle receiving monensin at recommended levels are safe for human consumption.  相似文献   

17.
Six studies involving 700 pigs were conducted in five separate swine research facilities to evaluate weight gain and efficiency of feed utilization in pigs fed the antibiotic efrotomycin. Pigs averaging 8.4 kg at the beginning of the studies were fed fortified corn-soybean meal diets that contained efrotomycin at 0, 2, 4, 8 or 16 ppm for an average of 120 d to market weight, about 92.1 kg. Pigs fed efrotomycin gained 5.9 to 8.9% faster (P less than .01) and were 1.7 to 4.0% more efficient (P less than .01) than those fed control diets. The improvement in growth rate was linear from 2 through 16 ppm, while feed efficiency (gain/feed) plateaued at 4 ppm efrotomycin. Treatment X study interactions were not significant for average daily gain or feed efficiency, showing that the response to efrotomycin was similar in each study. These studies indicate that efrotomycin is effective in improving gain and efficiency of feed utilization in swine from weaning until market weight.  相似文献   

18.
Adult and kit male and female natural dark ranch mink (Mustela vison) were fed a conventional diet supplemented with 0, 500, 1,000, or 1,500 ppm zinc, as ZnSO4.7H2O, for 144 days. No marked adverse effects were observed in feed consumption, body weight gains, hematologic parameters, fur quality, or survival. Zinc concentrations in liver, kidney, and pancreas of the mink increased in direct proportion to the zinc content of the diet. Histopathologic examination of the livers, kidneys, and pancreata revealed no lesions indicative of zinc toxicosis. The results indicate that mink can tolerate at least 1,500 ppm dietary zinc, as ZnSO4.7H2O, for several months without apparent adverse effects.  相似文献   

19.
Ochratoxin A (OA) was incorporated in the diets of growing gilts (mean body weight, 20.1 kg) at a concentration of 2.5 mg of OA/kg of feed and was fed continuously for 35 days. Humoral and cell-mediated immunologic measurements were evaluated to determine the effects of OA on immune function in swine. Cutaneous basophil hypersensitivity to phytohemagglutinin (PHA), delayed hypersensitivity to tuberculin, PHA-induced lymphocyte blastogenesis, interleukin-2 production, total and isotype immunoglobulin concentrations, antibody response to chicken RBC, and macrophage activation were used to evaluate immune function. Gilts treated with OA had reduced cutaneous basophil hypersensitivity response to PHA, reduced delayed hypersensitivity to tuberculin, decreased stimulation index for lymphoblastogenesis, decreased interleukin-2 production when lymphocytes were stimulated with concanavalin A, and decreased number and phagocytic activity of macrophages. Differences were not observed for total and isotype immunoglobulin concentrations, or humoral hemagglutination (chicken RBC) titer. These data indicate that OA may suppress cell-mediated immune response in growing swine.  相似文献   

20.
Young male rats were fed a diet containing 0, 1, 10, 100, or 500 ppm of a commercial mixture of polybrominated biphenyls (PBB) that had been accidentally incorporated into a mineral mixture and fed to Michigan livestock and poultry. After 30 days, 9 of the 12 rats in each group were killed and tissues were examined. Liver weight to body weight ratios were significantly increased at all feeding levels; at 500 ppm, liver weight had more than doubled. Kidney weight was not affected. Microscopic lesions were mostly confined to the liver and consisted of extensive swelling and vacuolation of hepatocytes in rats fed diets containing 100 and 500 ppm of PBB. Slight swelling and vacuolation were seen in rats fed the diet containing 10 ppm, and lesions were not found at 0 or 1 ppm. There was a significant increase in hepatic mitochondrial size at 1 ppm, and smooth endoplasmic reticulum was markedly increased at 100 and 500 ppm. Myelin bodies were present at 100 and 500 ppm, and vacuoles were numerous. Rats killed at 60 days had similar lesions. The activity of hepatic microsomal enzymes increased at all levels of feeding of PBB. Rat pups nursing dams fed a diet containing 10 ppm of PBB had microscopic and ultrastructural hepatic lesions. When guinea pigs were fed PBB at the same amounts as were rats, the results were strikingly different. Guinea pigs fed a diet containing 500 ppm of PBB died within 15 days; at 100 ppm, only 2 of 6 survived for 30 days. Effects on liver weight were inconsistent, but 2 of 6 fed a diet containing 10 ppm had enlarged livers.  相似文献   

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