Evaluation of lasalocid as a coccidiostat in calves: titration, efficacy, and comparison with monensin and decoquinate

Two experiments were conducted to evaluate lasalocid as a coccidiostat in Holstein calves and to compare lasalocid with monensin and decoquinate. In experiment 1, calves in 3 groups (6 calves/group) were each inoculated with 500,000 sporulated oocysts, 88% of which were Eimeria bovis and 12% were E zuernii. Calves in each group were given lasalocid-medicated feed at 0.50 (group 3), 0.75 (group 4), or 1 mg/kg (group 5) of body weight/day for 45 days. Two control groups (6 calves/group) were also evaluated; calves in control group 2 were inoculated and nontreated, and calves in control group 1 were noninoculated and nontreated. At 0.50, 0.75, or 1 mg/kg/day, lasalocid was equally effective in preventing induced coccidiosis (E bovis and E zuernii) in calves. Compared with inoculated nontreated controls, treated calves had significantly (P less than 0.05) fewer oocysts in feces and had fewer clinical signs of coccidiosis from days 16 to 30 after inoculation. Experiment 2 was conducted to compare the effectiveness of monensin, lasalocid, and decoquinate for the prevention of experimentally induced coccidiosis. Calves (n = 48) were allotted into 4 groups (12 calves/group); each was inoculated orally with 275,000 sporulated oocysts, predominantly E bovis and E zuernii, and each was given nonmedicated feed (group 6) or feed medicated with 33 mg of lasalocid (group 7), decoquinate (group 8), or monensin (group 9)/kg of feed for 46 days. Calves given medicated rations had significantly (P less than 0.05) fewer oocysts in their feces and fewer clinical signs of coccidiosis than did calves given nonmedicated rations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Control of bovine coccidiosis with monensin: in nonresistant newborn calves

Newborn Holstein male calves were purchased within 3 days after birth and were removed from the local farms to the Dixon Springs Agricultural Research Center. They were hand-fed for 7 weeks and then weaned to a prepared feed. Eight groups, each of 4 calves, were housed in separate pens. In each of 4 pens (pens 2 to 5), 1 calf was inoculated with sporulated oocysts of Eimeria bovis (and was not medicated); 1 calf was inoculated and given feed with added monensin at the dosage level of 10 g/906 kg of feed; and 2 calves were inoculated and given medicated feed with added monensin at the dosage level of 20 g/906 kg or 30 g/906 kg. In the 4 other pens (6 to 9), the calves were inoculated with E zuernii and otherwise were given feed without or with added monensin as in pens 2 through 5. Another group of 5 calves (all kept in 1 pen), served as noninoculated, nonmedicated controls. At 14 days after inoculations with E bovis, the single calves in each of the 4 pens that were given the nonmedicated feed began to show clinical signs of coccidiosis and discharged increasing numbers of oocysts. The other inoculated calves (given monensin) had fewer clinical signs and discharged fewer oocysts in the feces as the level of medication in the feed increased. The calves inoculated with E zuernii developed only moderately severe infections when compared with those inoculated with E bovis. Inoculated (with E bovis) nonmedicated calves had severe reductions in feed consumption and weight, and 3 of 4 died.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative therapeutic effect of toltrazuril, sulphadimidine and amprolium on Eimeria bovis and Eimeria zuernii given at different times following infection in buffalo calves (Bubalus bubalis)

We compared the therapeutic effect of three anticoccidial drugs (toltrazuril, sulphadimidine and amprolium) in buffalo (Bubalus bubalis) calves experimentally infected with Eimeria bovis (E. bovis) and E. zuernii oocysts (3 x 104oocyst/calf). Buffalo calves (1.5-4 month old, 70-kg body weight) were randomly allocated into 3 groups (9 calves each). Group T was experimentally infected with oocysts and treated with toltrazuril (20 mg/kg BW twice orally at a 1-week interval). Group S was experimentally infected with oocysts and treated with sulphadimidine (125 mg/kg injected IM followed by half dose for 4 successive days). Group A was experimentally infected with oocysts and treated with amprolium (50 mg/kg orally for 7 successive days). Each group had three subgroups (three calves/subgroup) to represent timing of the drug administration: 1st day of coccidia infection (FD), onset of clinical signs of coccidiosis (CC), and onset of oocyst shedding into the faeces (OS). Clinical signs, body-weight gain (BWG) and number of oocysts per gram feces (OPG) were monitored daily for 35 days post-infection (DPI). The OPG were reduced (but the BWG was not different) in the T calves compared to S and A calves. Within the same group, treatment from the 1st day of infection reduced the OPG and increased the BWG compared to the later treatment timings.     

Quantitative determination of coccidian oocysts in beef calves from the coastal plain area of Georgia (U.S.A.)

For two consecutive years, determinations were made of the prevalence and abundance of coccidian oocysts from crossbred beef calves raised on Bahia grass pastures in the coastal plain area of Georgia. Of the 534 fecal samples collected during the survey, 461 (86.3%) contained one or more species of coccidian oocysts. The total mean oocysts per gram of feces (OPG) was significantly different (P less than 0.10) between the two years. Thirteen species of Eimeria were found during both years of the survey. Eimeria bovis was the most prevalent species found in the survey; E. ellipsoidalis, however, had the greatest number of OPG. Eimeria bukidnonensis, E. pellita, and E. brasiliensis were the least prevalent species and also had the lowest numbers of OPG. Only one clinical case of coccidiosis was seen. A nine-month-old calf had E. zuernii coccidiosis; it excreted E. zuernii oocysts in several fecal samples before the clinical disease appeared.     

Control of coccidia in young calves using lasalocid

SUMMARY Thirty-six, 2- to 4-day-old Friesian bull calves were divided into 4 groups and fed milk replacer and calf starter pellets ad libitum in separate pens. Four treatments were applied; lasalocid in milk (1 mg/kg body weight/day) (M), lasalocid in starter (F), lasalocid in both milk and starter (M+F) and untreated (C). When the calves were about 2 weeks old they were each dosed orally with 550 000 sporulated Eimeria sp oocysts, mainly E zurneii and E bovis. The infection, detected by faecal excretion of oocysts, was suppressed in the M+F and M groups. There was significant excretion of oocysts in the F group but these calves did not show any clinical signs of coccidiosis. Untreated calves were affected with diarrhoea containing blood on the 24th day after inoculation. Body weight gain and intake of starter pellets was also depressed in the untreated calves during the time they were clinically affected. It is concluded that mixing lasalocid in milk replacer (or fresh milk) is an effective method of protecting young calves against early infection with coccidia.     

The effect of a metaphylactic treatment with diclazuril (Vecoxan) on the oocyst excretion and growth performance of calves exposed to a natural Eimeria infection

A multicenter field efficacy study was performed in six farms located in Belgium, France and Germany with a history of suspected coccidiosis outbreaks and the proven presence of Eimeria bovis and/or Eimeria zuernii. At each of these trial sites the calves were randomly allocated to two groups (T, treated; C, control) of similar size. In total, 231 calves were included in the study. Group T calves (n=116) were drenched with a single dose of diclazuril (Vecoxan, 1mg/kg body weight) close to the time of expected outbreak of coccidiosis (day 1 of the study period), group C calves (n=115) served as placebo-treated controls. Although E. bovis and/or E. zuernii were identified at all trial sites, clinical coccidiosis was only noted in 16% of the group C calves. At day 5 of the study period (4 days after treatment), faecal oocyst counts (opg, oocysts per gram) were substantially lower in group T ("short-term effect") compared to group C. At four trial sites, the respective values of groups T and C were significantly different (P=0.0132 to P=0.0001) in favour of group T. For the pooled data of all trial sites, this effect was highly significant (P<0.0001). The overall faecal oocyst counts from day 3 until day 21 of the study period ("Area Under the Curve") was significantly reduced in group T by 87.2-99.5% ("long-term effect") at five trial sites (P=0.0139 to P<0.0001). The pooled data revealed a highly significant effect of treatment on oocyst excretion over the observation period (P<0.0001). On five of the six trial sites, the average weight gain was higher in group T than in group C. On those trial sites, the average weight gain of group T calves exceeded that of the controls by 95-268g/day and by 2.0-6.0kg over the study period. This effect was statistically significant (P<0.01) at one trial site. Altogether the calves of group T gained on average 129g more weight daily than the controls (+2.7kg over the study period). For these pooled data, statistical analysis confirmed the positive effect of treatment of calves exposed to coccidiosis on growth performance (P=0.003). In conclusion, metaphylactic treatment with diclazuril efficiently controls coccidiosis in calves thus reducing environmental contamination with oocysts and preventing negative effects of natural exposure to coccidiosis on growth performance of calves.     

Experimental Infection of Newborn Calves with Coccidia and Reinfection after Weaning

Four newborn Hereford calves were orally inoculated five times with 100 sporulated oocysts of coccidia, predominantly Eimeria zurnii. Each calf was kept isolated with its dam until weaned at the age of 13 weeks. Three other newborn calves were similarly isolated but not experimentally infected. The calves were then challenged with 300,000 sporulated oocysts at the age of five, seven and nine months. The previously unexposed calves developed marked clinical coccidiosis after the first challenge, but resisted the second and third challenge. The neonatally exposed calves were susceptible to infection at the first challenge as well as to the next two challenges at seven and nine months of age, but the clinical signs following the last two challenges were milder than those of the first challenge. These findings suggest that under conditions where calves become infected with coccidia when very young, such calves may, by shedding oocysts in large numbers for long periods, be a continuing source of coccidial infections to other animals.     

Changes in the blood composition of calves during experimental and natural infections with Eimeria alabamensis

Two trials were carried out to assess the changes in blood composition of calves infected either experimentally or naturally with Eimeria alabamensis. In the first, 12 calves were dosed orally with 10 to 400 million sporulated oocysts and compared with three control calves. The second trial used eight calves turned out to graze a permanent pasture known to induce E alabamensis coccidiosis in calves and eight calves turned out on to a previously ungrazed pasture. In both trials the serum activities of glutamate dehydrogenase (GLDH) and alkaline phosphatase (AP) and the serum concentration of total bile acids decreased in the infected animals while total bilirubin increased. The changes in GLDH, bile acids and bilirubin were most pronounced just before the calves began to excrete oocysts. In the first trial the lowest AP activity was observed 10 days after infection, but in the second its activity continued to decrease throughout the trial. In the first trial haematology, serum fibrinogen, total protein and protein fractions were also investigated. All the significant changes were small and the potential of the investigated blood components as diagnostic markers is therefore minimal.     

Vitamin E supplementation of newly arrived feedlot calves

Seven hundred fifteen crossbred (primarily British) calves purchased in southern Oklahoma and northern Texas auction barns were received at the Willard Sparks Beef Research Center, Stillwater, OK, and used to study effects of duration (days) of vitamin E feeding during a 42-d receiving period on animal performance, health, and serum cholesterol and vitamin E concentrations. Upon arrival, calves were blocked by load (seven loads), sorted by BW (light, n = 4 pens per load; and heavy, n = 4 pens per load), and assigned randomly to one of four dietary treatments (n = 2 pens per load; 14 pens per treatment). Experimental diets were formulated to provide 2,000 IU.calf(-1).d(-1) of supplemental vitamin E (dl-alpha-tocopherol acetate) for 0 (CON), 7 (E7), 14 (E14), or 28 (E28) d. Vitamin E was delivered in a pelleted supplement that was added to the basal diet in decreasing concentrations as DMI increased (2.0 kg of DMI = 6%; 4.0 kg of DMI = 4%; and 6.0 kg of DMI = 2%). Serum samples were collected on d 0, 14, 28, and 42 for determination of cholesterol, alpha-tocopherol (d 0, 28, and 42), and antibody (IgG) concentrations. Duration of vitamin E supplementation did not affect ADG (0.98 kg/d; P = 0.56) or G:F (0.189; P = 0.87). Serum cholesterol concentrations decreased (day effect; P < 0.001) for all treatments from d 0 (average = 127 mg/100 mL) to 14 (average = 62 mg/100 mL). Serum alpha-tocopherol decreased (day effect; P < 0.001) from d 0 (5.2 microg/mL) to 28 (1.8 microg/mL); however, on d 28, a greater (P < 0.001) serum alpha-tocopherol concentration was observed for E28 (3.4 microg/mL) calves than for CON (1.1 microg/mL), E7 (1.2 microg/mL), or E14 (1.5 microg/mL) calves. Respiratory disease was diagnosed in 64.6% of calves in this study. Medical costs were less (P = 0.08) for calves fed vitamin E for 28 d (4.88 dollars/calf) than for calves fed the control diet (6.29 dollars/calf). Carcass characteristics were not affected (P = 0.19 to 0.88) by dietary treatments. Supplemental vitamin E formulated for 2,000 IU.calf(-1).d(-1) had little influence on performance and overall health status of calves under our experimental conditions; however, the increased serum concentrations of alpha-tocopherol when vitamin E was fed for 28 d suggests that any potential effects of vitamin E on health status might be time-dependent.     

Some pathophysiological changes associated with infection of Eimeria zuernii in calves.

Twelve Holstein-Friesian calves were divided into two groups, one of which was infected with Eimeria zuernii. Fecal oocyst output, weight changes and various blood, cellular, protein and biochemical constituents were examined for both groups. Maximal fecal oocyst output occurred 21 days after infection. Both groups of calves gained weight in a linear fashion until day 21 postinfection when the infected group lost weight rapidly. The packed cell volume of the infected calves appeared markedly reduced. Although there was a reduction in plasma proteins it did not appear significant. There was a significant reduction in plasma Na+ and Cl- ions of the infected calves. There were no significant changes in the other blood constituents examined.     

Dynamics of Eimeria oocyst excretion in dairy calves in the Province of Buenos Aires (Argentina), during their first 2 months of age

Clinical coccidiosis is associated with high fecal contamination and stress situations, mainly in animals under 1 year of age. Artificially fed dairy calves are one of the categories most prone to suffer from this parasitic disease. The study was carried out in a commercial dairy farm. Feces samples of heifer calves between 2 and 8 weeks old were taken monthly for oocyst counts and Eimeria spp. identification. Of the 862 feces samples analyzed, 48% presented oocysts. When grouping the results of monthly samplings of each age group, it was observed that this percentage increased in the group of calves between 20 and 40 days of life, reaching the peak average of 85% of infection prevalence in the group with between 26 and 30 days of age. The discharge of oocysts observed between 21 and 35 days of age was superior to the rest (p<0.05). This trend appeared every month throughout the whole year. However, during March, April, June, September and November, the curves in the group categories were higher than in the remaining months (p<0.05). Twelve Eimeria species were identified, being E. ellipsoidalis, E. bovis, E. zuernii and E. auburnensis those in highest numbers. E. ellipsoidalis had an important predominance in the opg composition, >75% up to 25 days of life (p<0.05). E. bovis reached peak values in the 26 and 30 days group (p<0.05), remaining without significant variations in the last stage of the artificial milk feeding period (approximately 60 days of life), when the oocyst counts were significantly low. Oocysts of E. auburnensis appeared in great proportion (46%) in the cultures later than the previous species (p<0.05), in calves of the age groups of between 46 and 50 days of age. Oocysts of E. zuernii showed no trend associated with age. The highest prevalence of infection and of oocyst values appeared during the periods with better environmental conditions for sporulation, survival and dispersion of oocysts (spring and autumn), coincident with the highest birth rates and an elevated number of calves in the paddock. Calves developed a process of natural "vaccination" against coccidiosis. This was demonstrated by the decrease in the quantity of animals shedding oocysts and in the number of oocysts eliminated at the end of the artificial milk feeding period.     

Occurrence and diversity of bovine coccidia at three localities in South Africa.

Information on the occurrence and diversity of coccidia infecting cattle in different farming systems in South Africa is lacking. The objective of the study was to determine the levels of infection of coccidia in cattle at three localities and to determine the Eimeria species occurring at each locality. Faecal samples (n=1936) were collected over a 13-month period from a dairy farm (Mallesons), a Bonsmara breeding farm (Kaalplaas) and a Nguni stud farm (Pienaars River). Samples were collected from adults >24 months old and calves <12 months old. The modified McMaster technique was used to determine OPG (oocysts per gram) of faeces. Samples with OPGs > or =2000 were allowed to sporulate in potassium dichromate solution at room temperature. Species identification was done by measurement and morphological characteristic of each species. At Mallesons, 29% of samples were positive, at Kaalplaas 50% and at Pienaars River 52%. The most prevalent species were Eimeria zuernii and E. ellipsoidalis at Mallesons, E. zuernii and E. bovis at Kaalplaas and E. bovis and E. zuernii at Pienaars River, respectively. Adults had very low OPGs. There was a pattern at the three localities in that high OPGs were only recorded in calves, which were also shedding the most pathogenic species.     

Experimental Winter Coccidiosis in Sheltered and Unsheltered Calves

Hereford calves, seven months old, were inoculated orally with sporulated oocysts of Eimeria bovis and E. zurnii and housed in a heated building together with uninoculated animals. Duplicate groups of similarly treated animals were left unsheltered in cold winter weather. Clinical coccidiosis developed in most of the inoculated calves, sheltered and unsheltered. There was no marked difference in the severity of the infections. The sheltered uninoculated contact animals remained clinically unaffected, but mild coccidiosis developed in the unsheltered controls.

The results suggest that cold may increase the host's susceptibility to clinical coccidiosis, but may not increase the severity of the signs once the clinical infection is established.

     

Hematology of experimental acute Sarcocystis bovicanis infection in calves. II. Serum biochemistry and hemostasis studies

Of four Holstein-Friesian calves infected with 200,000 sporocysts of Sarcocystis bovicanis, three become ill and died on days 35, 55, and 59 of a 63-day experiment. No control calves became ill or died. Serum biochemicals and hematologic indicators of hemostasis from both groups were measured throughout the experiment. Creatine phosphokinase values for both groups increased markedly during acute infection. Lactic dehydrogenase and aspartate aminotransferase values were high in infected calves on days 25 to 35 and days 24 to 63, respectively, indicating injury of muscle, liver, or other tissues. Sorbitol dehydrogenase values were significantly higher for infected than for control calves on days 25 and 35, indicating liver injury. Serum bilirubin and blood urea nitrogen values were significantly increased in three anemic infected calves from day 25 or 26 to day 35, probably reflecting destruction of erythrocytes. The fourth infected calf was not anemic and had no hyperbilirubinemia and only minimal azotemia. Serum protein and albumin values decreased in infected calves on days 21 to 30 or 35, when, although hypoalbuminemia persisted, total protein concentration increased. Glucose, calcium, sodium, and chloride values decreased in infected calves slightly before onset of illness and remained low throughout the experiment. Potassium, magnesium, and phosphorus values did not differ between infected and control calves. Activated partial thromboplastin time and Russell's viper venom time were normal; prothrombin time was significantly higher from day 27 to day 49 in infected calves. This pattern was interpreted as evidence for acquired factor VII deficiency. Abnormal retraction of blood clots and enlarged platelets in blood smears, which indicate platelet dysfunction and increased platelet turnover, respectively, were seen on days 27 through 35 in anemic infected calves. Values for thrombin time (three calves) and fibrin degradation product concentration (one calf) increased just before death of the infected calves.     

Coccidiosis associated with post-weaning diarrhoea in beef calves in a dry tropical region

The roles of helminths and coccidia in post-weaning diarrhoea in beef calves in the dry tropics were investigated. Diarrhoea occurred approximately one month after weaning in both anthelmintic treated and untreated calves. The highest numbers of coccidial oocysts were seen 29 days after weaning and 3 necropsies confirmed Eimeria zuernii coccidiosis. In the absence of wet overcrowded conditions, disease may have been precipitated by environmental interactions leading to suppression of host immunity. Other Eimeria identified were E. bukidnonensis, E. wyomingensis, E. bovis, E. auburnensis, E. cylindrica, E. ellipsoidalis and E. subspherica. The last 5 species are believed not to have been previously documented in Australia. The presence of E. canadensis was strongly suspected.     

In utero infection of cattle with Mycobacterium avium subsp. paratuberculosis: a critical review and meta-analysis

Mycobacterium avium subsp. paratuberculosis (Mptb) causes Johne's disease in ruminants. Disease control programmes aim to break the faecal-oral cow-calf transmission cycle through hygienic calf rearing and removal of affected cows from the herd, but these programmes do not take account of the potential for congenital infection. The aims of this study were to critically review research on in utero infection, determine the prevalence of fetal infection in cattle through meta-analysis and estimate the incidence of calves infected via the in utero route. About 9% (95% confidence limits 6-14%) of fetuses from subclinically infected cows and 39% (20-60%) from clinically affected cows were infected with Mptb (P<0.001). These are underestimates for methodological reasons. The estimated incidence of calf infection derived via the in utero route depends on within-herd prevalence and the ratio of sub-clinical to clinical cases among infected cows. Assuming 80:20 for the latter, estimates of incidence were in the range 0.44-1.2 infected calves per 100 cows per annum in herds with within-herd prevalence of 5%, and 3.5-9.3 calves in herds with 40% prevalence. These estimates were not markedly sensitive to the value chosen for the proportion of clinical cases. In utero transmission of Mptb could retard the success of disease control programmes if the opportunities for post natal transmission via colostrum/milk and environmental contamination were able to be controlled. The consequences of fetal infection for the calves so infected are discussed in the context of diagnosis and vaccination together with recommendations for future research.     

Infection by Salmonella typhimurium, S. agona, S. enteritidis or S. infantis of chicks with caecal coccidiosis

Experimental infections of Salmonella typhimurium, S. agona, S. enteritidis or S. infantis were studied in chicks infected with Eimeria tenella. In all experiments, 4-d old birds were given 5 daily oral doses of approximately 10(4) salmonella organisms per bird. One day before this inoculation one group of birds received a single dose, in the range 1 X 10(4) to 4 X 10(4) sporulated oocysts of E. tenella per os whilst the other group was not inoculated and served as the control. Chicks were examined post morten 7, 10 or 14 d after receiving coccidia. With S. typhimurium infection, the number of salmonellas in the caeca of the E. tenella-infected birds was greater than in those infected only with salmonella. With S. agona and S. enteritidis, the counts of salmonella in the caeca and the numbers of birds positive for salmonella in the caeca and liver were greater in the E. tenella-infected birds. The rate of infection of S. infantis was not increased by caecal coccidiosis.     

Evaluation of diagnostic tests for Johne's disease in young cattle

OBJECTIVE: To investigate the development of immune responses in calves experimentally and naturally infected with Mycobacterium paratuberculosis and to evaluate the potential for diagnostic tests to detect infected calves. DESIGN: Sequential testing of four treatment groups of calves over a 2 year period. PROCEDURE: Twenty-nine calves were allocated to four groups. Group D calves were orally dosed with M paratuberculosis, group N calves naturally exposed to M paratuberculosis, group V calves vaccinated for M paratuberculosis, and group C were control calves (not infected or vaccinated). Blood and faecal specimens were collected from each calf at monthly intervals to 18 months of age and then every 2 months until they were slaughtered between the ages of 21 and 29 months. Specimens were tested using absorbed EIA, IFN-gamma EIA and faecal culture. The infection status of the calves was confirmed by extensive histopathological examination and tissue culture. RESULTS: M paratuberculosis infection was confirmed in 10 calves, comprising six of eight orally dosed calves, three of five naturally exposed calves and one of nine vaccinated calves. The six artificially infected calves and one naturally infected calf were detected shedding M paratuberculosis in their faeces. Results with positive absorbed EIA were obtained from one artificially infected calf, one naturally infected calf and three vaccinated calves. All calves including controls had positive results on at least one occasion using the IFN-gamma EIA. In addition, seven calves had positive bovine tuberculosis results using the IFN-gamma EIA, even though bovine tuberculosis has been eradicated from Australia. CONCLUSION: Detection of M paratuberculosis infection in young cattle continues to be difficult using current tests.     

Ostertagia ostertagi infection in the calf: effects of a trickle challenge on the hormonal control of digestive and metabolic function

Metabolic effects of a trickle challenge with the equivalent of 10,000 infective Ostertagia ostertagi larvae per day were investigated in 12 calves allocated to infected, pair-fed control or ad libitum-fed control groups. Changes in hormone levels reflecting abomasal, pituitary and pancreatic function were monitored using radioimmunoassay techniques previously validated for use in cattle. A range of metabolic profile parameters and blood metabolites was also measured. Feed intake of the infected calves began to decline as blood gastrin and pepsinogen levels reached a peak. The depression in appetite recorded in this group was responsible for significant increases in plasma urea and non-esterified fatty acid levels and associated with an increase in growth hormone/insulin ratio. No significant difference in glucagon levels was recorded between groups. A decline in blood albumin values was also shown in the infected group and associated with a drop in nitrogen digestibility. A significant depression in circulating calcium levels was related to either the hypoalbuminaemia or impaired mineral absorption in the intestine. A decrease in plasma cholesterol values in the infected group was associated with changes in digestive function.     

柔嫩艾美尔球虫感染对鸡的若干生理生化指标的影响

以74只33日龄蛋公鸡作为试验对象,随机分成感染组(n=37)和对照组(n=37)。感染组每只口服接种1.5×10~5个柔嫩艾美尔球虫孢子化卵囊,分别于感染前(0d)和感染后(2,4,6,8d)将鸡处死,颈静脉采血,研究球虫感染对鸡生理生化指标的影响。结果表明柔嫩艾美尔球虫感染后鸡红细胞数、白细胞数、血红蛋白含量、血清中葡萄糖含量显著减少,血清钾含量显著升高,血清钠、血清钙、氯化物、无机磷都显著降低。血清镁含量也降低,但与对照组相比无统计学差异。