Bermudagrass management in the Southern Piedmont USA. V: Gastrointestinal parasite control in cattle.

Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae. The experimental design was a randomized complete block (landscape features) with a split plot arrangement of treatments where main plots were pasture fertilization treatments (mineral, clover plus mineral, and broiler litter) and split plots were low and high forage mass. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 h prior to stocking of pastures, with the cattle remaining in drylot during the 48-h period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994 to 1998, steers grazed the paddocks for a 140-day period from mid May until early October each year. Fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals, thereafter. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. In traditional management systems, cattle graze parasite-contaminated pastures; therefore, parasites negatively impact growth and productivity throughout the entire grazing period. Periodic anthelmintic treatments simply give a temporary reprieve from those parasitic infections. Conceptually, using the current grazing system, it should be possible to maintain these pastures in a parasite-free status indefinitely; however, from a drug resistance perspective, it would be most applicable in sod-based rotation systems where cattle graze from two to five years before land is returned to row-crops. By removing the effect of parasites, cattle can grow without the physiological constraints that gastrointestinal parasites place on appetite, digestion, nutrient utilization, and general well being.

Efficacy of a pour-on formulation of eprinomectin (MK-397) against nematode parasites of cattle, with emphasis on inhibited early fourth-stage larvae of Ostertagia spp.

OBJECTIVE: To evaluate efficacy of topically applied eprinomectin against inhibited early fourth-stage larvae (IL4) of Ostertagia spp in calves. ANIMALS: 4 groups (n = 6 [replicates]) for dose titration; 2 groups (n = 8 calves [replicates]) for dose confirmation. PROCEDURE: 2 dose titration studies-0, 125, 250, and 500 micrograms of eprinomectin/kg of body weight-Louisiana and Georgia- and 2 dose confirmation studies of selected therapeutic dosage (500 micrograms/kg) in Scotland and France. Monitor calves were used to determine inhibition percentage of Ostertagia IL4. Test calves were ranked by weight in replicates of 4 (titration trials) or 2 (confirmation trials) animals each, and within replicates, were randomly allocated to treatment groups. Drug treatments were done on day 0, and animals were euthanatized by replicate, with holding time between treatment and euthanasia varying among trials from 14 to 27 days. RESULTS: Observations indicated high efficacy (> 99%) of 500 micrograms of eprinomectin/kg in removal of Ostertagia IL4. Ostertagia and Cooperia were only genera common across sites, with efficacy of aforementioned dosage against adult and larval stages of both genera consistently high (> 99%). Results of 1 or both titration studies (500 micrograms/kg) indicated > 99 to 100% efficacy against adult Haemonchus placei, Trichostrongylus axei, T colubriformis, Bunostomum phlebotomum, Dictyocaulus viviparus, and Oesophagostomum radiatum. Lower efficacy values were observed at minimal (125 micrograms/kg) dosage. In France, 500 micrograms/kg was 85% effective against Trichostrongylus spp adults; however, numbers of control calves infected with Trichostrongylus spp and degree of infection were low. Adverse reactions were not evident. CONCLUSION: Eprinomectin given topically (500 micrograms) was highly effective against Ostertagia IL4 and other common nematodes of cattle.

Anthelmintic efficacy of febantel paste in naturally infected calves.

The purpose of the present study was to verify results of the lowest dose (5 mg kg-1) of febantel evaluated in an earlier trial in which there were no differences in efficacies of three dose rates (5, 7.5 and 10 mg kg-1 body weight) against natural gastrointestinal nematode infections of cattle. Fourteen Angus calves (mean weight and age of 155 kg and 525 days, respectively), from the same farm, with relatively heavy (mean of 448 eggs g-1 feces (epg] parasite burdens were selected. After an adjustment period of 8 days in drylot, beginning on 25 July, seven calves were treated with a 45.5% paste formulation of febantel. On Day 7 post-treatment, calves were necropsied for determination of residual worms. Rectal fecal samples were obtained prior to adjustment, at treatment, 5 days post-treatment and at necropsy. On both Day 5 post-treatment and at necropsy a mean of less than 1 epg was recovered from treated calves compared with 765 and 1566 epg, respectively, in control calves. Worms counts at necropsy revealed an efficacy of 98.5% against all adult abomasal worms (Haemonchus placei, 100%, P less than 0.02; Trichostrongylus axei, 99.4%, P less than 0.0001; Ostertagia ostertagi, 90.5%, P less than 0.0002). Treatment was 100% efficacious against adult small and large intestinal worms. However, numbers of Bunostomum phlebotomum, O. radiatum and Trichuris spp. recovered in the control calves were too low to enable a reliable test of drug efficacy. Treatment was not effective against either mucosal or luminal fourth stage larvae of abomasal O. ostertagi.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a single strategically timed dose of fenbendazole on cow and calf performance.

A 168-day study was conducted to evaluate the effect of a strategically timed treatment with fenbendazole on anthelmintic efficacy and performance of beef cows and calves. Eight groups of 10 Angus cow/calf pairs were allotted on 7 May 1987 to eight similarly managed 4.86-ha pastures (bermudagrass/tall fescue) on the basis of cow age, and calf sex and weight. At that time, four groups of cows received a dose of fenbendazole (5 mg kg-1) with their calves receiving fenbendazole at the same dosage 28 days later. Treated calf average daily gain (ADG) was 0.04 kg greater (P less than 0.05) than control calves (0.82 vs. 0.78 kg) during the 168-day study. Treated cow ADG was 0.09 kg greater (P less than 0.05) than control cows (0.40 vs. 0.31 kg). Although there was a reduction (P less than 0.05) in fecal egg counts following treatment of the cows, the numbers of eggs generally were low compared with egg counts of calves. From Day 28 through Day 112 post-treatment, fecal egg counts of treated calves were lower (P less than 0.05) than those of control calves. However, fecal egg counts from treated calves increased post-treatment until there were no differences (P greater than 0.05) between treated and control calves at the end of the study. The pregnancy rate tended to be higher (P = 0.12) for treated cows (98%) than for untreated control cows (75%). The actual calving rate was higher (P = 0.03), for treated cows (90%) than for untreated control cows (68%). Results indicated that a strategic anthelmintic treatment can improve cow and calf performance, but that calves born in late winter or early spring may need more than one therapeutic dose during the nursing period on pasture.

Efficacy of morantel sustained-release bolus in control of gastrointestinal nematodes of weaned calves during the autumn-winter grazing season.

A 168-day study was conducted to evaluate the efficacy of morantel tartrate sustained-release bolus (MSRB) in controlling gastrointestinal parasitism in weaned calves during autumn-winter grazing in the temperature climate of southern United States. Sixty-two weanling Angus heifers were used to assess treatment differences. Six sentinel heifers were necropsied to assess pretrial gastrointestinal worm counts. The remaining 56 heifers were assigned to 4 groups of 14 heifers each and were placed on four 4.86-hectare dormant Bermuda grass pastures (1 group/pasture) that had been no-till interseeded with cereal rye in early October. Heifers in 2 groups were given 1 MSRB in early November; the other 2 groups served as nonmedicated controls. Three heifers (principals) from each of the 4 groups were necropsied on posttreatment days 57, 112, and 168 (end of study) for total worm recovery. Eight 5-month-old tracer steers, raised worm-free from birth, grazed the 4 pastures (2/pastures) for the first 21 days of the study and then were kept in drylot for 21 days before being necropsied. Level of larval contamination of pastures grazed by control and MSRB-treated heifers were comparable, because the mean number of nematodes recovered from tracer steers grazing the control and MSRB pastures were 47,449 and 53,835, respectively. At 28 days after treatment, MSRB-treated heifers had lower (P less than 0.05) mean egg counts/g of feces than did control heifers (280 vs 13).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the morantel sustained release bolus in cows and calves.

The efficacy of the morantel sustained release bolus (MSRB) in controlling gastrointestinal parasitism in beef cattle was assessed during the 1982 spring-autumn grazing season. Forty-eight cows and their calves were allotted to three equal groups. One group (T-1) served as a nonmedicated control group. One MSRB was administered to each calf of the T-2 group, and to each cow and calf of the T-3 group at the beginning of the study. The efficacy of the bolus was assessed by comparison of weight gain performance and parasitological data (fecal worm egg counts, herbage larval counts, worm counts from tracer and principal trial calves, and plasma pepsinogen level determinations). Though not statistically significant, treated calves from Group T-2 had a numerical mean weight gain advantage of 2.6 kg, and those from Group T-3 of 4.7 kg, over control calves. Average daily gains (ADG) for the three groups of calves were 0.69, 0.72, and 0.73 kg, respectively. Untreated cows from Group T-2 and treated cows from Group T-3 outperformed the control cows by 12.3 and 7.5 kg, respectively. Fecal worm egg counts from both groups of treated calves were significantly (P less than 0.01) lower than counts from control calves during the entire 169-day trial; notably, egg counts were reduced by 99% 28 days after MSRB administration to both groups of calves. There were no significant differences in the number of eggs counted from the three groups of cows, probably because of the very low numbers of eggs encountered. Mean total worm burdens of principal calves (six per group) necropsied at trial termination indicated a 91% (P less than 0.01) reduction in Group T-2 and an 87% reduction (P less than 0.01) in Group T-3. Worm-free tracer calves were introduced onto pastures every 28 days to monitor availability of infective larvae. The mean number of worms recovered at necropsy from tracer calves that grazed with control cattle increased as the season progressed. However, the numbers of parasites recovered each month from mid-August through mid-October from tracers that grazed pastures with treated cattle were lower (P less than 0.05) than those levels displayed at trial initiation. In addition, the mean numbers of worms from treated group tracers were lower than from the controls for each necropsy period.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of the parasitological and production responses of a cow/calf operation to an anthelmintic program with ivermectin.

The efficacy of a treatment schedule using ivermectin, given subcutaneously at the rate of 200 micrograms kg-1, to control gastrointestinal parasitism and its effect on liveweight gains was assessed. Two herds with a total of 466 Hereford X Brangus cow/calf pairs were used. Each herd was on six pasture plots of comparable size, stocking rate, and quality and quantity of forage. Pasture groups were paired across the two herds. Pasture groups from one herd were randomly assigned to nonmedicated control and the other three to ivermectin treatment. Treatment assignments per pasture group were reversed in the other herd. The control group contained 118 cows and 112 calves and the medicated group 121 cows and 115 calves. Cows were treated in early July and the calves in late July or early August. Cattle from one herd were weighed on Days -28, 0 (day of cow treatment), 30 (day of calf treatment), 58, and 86, while the other herd was weighed on Days -29, 0 (day of cow treatment), 27 (day of calf treatment), 61, and 89. Day 0 was not the same calendar day for the two herds. Fecal samples for parasite egg counts were obtained from the rectum on weight days from five cows and six calves from each pasture; in most cases the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves between day of treatment for cows and the end of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Ostertagia ostertagi: excretory secretory chemotactic substance from infective larvae as cause of eosinophil locomotion.

The infective (third stage) larva of Ostertagia ostertagi produced an excretory secretory substance that is chemotactic for bovine eosinophils. The eosinophil chemotactic substance was present in supernatants of larval cultures within 6 hr of incubation in Eagle's Minimum Essential Medium containing 25 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid. The substance responsible for eosinophil chemotaxis has activity in small amounts, a molecular weight (MW) greater than 2000, and is heat labile at 100 C. Bovine eosinophils appeared to have a receptor for the chemotactic excretory secretory substance which is either identical or structurally similar to the previously described eosinophil chemotactic substance present in soluble third stage larval extracts. The larval substance may cause eosinophil accumulation in the abomasal tissue of cattle with ostertagiasis.

Effect of a once-daily suckling program on gastrointestinal parasitism in Angus cows and calves.

Over a 2-year period involving a total of 168 Angus cows and their calves, 2 studies were conducted to evaluate the effect of once-daily suckling on cow reproduction, calf growth, and gastrointestinal parasitism. Experiment I compared 2 restricted suckling (RS) groups with 1 normal suckling (NS) group. Each group consisted of 24 cows with their calves (24 cows-calves/group = 24 cows and 24 calves/group). In the RS groups, suckling by the calves was restricted to once a day for 45 days, and then the calves were allowed to suckle normally throughout the remainder of the experiment. In the NS group, the calves suckled normally throughout the experiment. Experiment II compared 2 groups of RS cow-calves (24 cow-calves/group) with 2 groups of 24 NS cow-calves/group. In experiment I, there were no differences (P less than 0.05) in pregnancy rate or in the average number of nematode eggs/g of feces (epg) between the cows from the 2 treatment groups. The RS calves consistently had higher epg counts than did the NS calves during the 45 days of RS (169 vs 62 epg, P less than 0.05) and from the time of their return to pasture until weaning (266 vs 186 EPG, P = 0.27). The RS calves also had a higher average coccidia oocyst count during the RS period only. In experiment II, RS cows had a higher pregnancy rate (87.6% vs 66.0%, P less than 0.05) and a shorter postpartum interval (83 vs 101 days, P less than 0.05) than did NS cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ivermectin on performance of beef cattle on Georgia pastures.

A total of 469 cows and calves from 2 herds, each on 6 pastures, was used to evaluate the anthelmintic efficacy and animal-performance benefits of ivermectin given subcutaneously at a dosage of 200 micrograms/kg to nursing beef calves and their dams during a grazing season. Pastures were paired across the 2 herds. Three pasture groups from 1 herd were randomly assigned to either a nonmedicated control or to a medicated group. Treatment assignments were reversed in the other herd. The control groups comprised 110 cows and 108 calves, whereas 127 cows and 124 calves were treated with ivermectin (200 micrograms/kg). The cows were treated once, in late spring, and the calves were treated twice, once in late spring and again in midsummer. Cattle from one herd were weighed on days - 12, 21, 49, 77 (day of 2nd treatment for calves), and 105, and the other herd was weighed on days - 6, 23, 57, 86 (day of 2nd treatment for calves), and 113. Rectal fecal samples for nematode egg counts were obtained from approximately 25% of the cattle in each pasture on weighing days; usually, the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves up to the 2nd treatment date and up to the termination of the study. There was no significant difference between treated and control cows, with regard to weight gain over either interval. Treated calves had fewer positive fecal egg counts (P less than 0.01) and passed fewer eggs (P less than 0.05) after both treatments than did control calves. There were no differences in either number of eggs or number of negative cows between treatment groups. Adverse reactions attributable to treatment were not seen.

Coccidia in cows and calves on pasture in north Georgia (U.S.A.).

The prevalence and abundance of coccidian oocysts were determined in a herd of beef cows and calves on fescue pastures in the Piedmont area of Georgia during 4-consecutive grazing seasons. Twelve species of Eimeria were found in the feces of the calves and 10 species were found in the feces of the cows. Eimeria bovis was the most prevalent species found in both the calves and cows. It occurred in 72.5% of 1090 samples from the calves and 10.2% of 719 samples from cows. Eimeria bovis also comprised the majority of oocysts present in the fecal samples from the calves and cows. The greatest number of E. bovis in a sample was 45 800 oocysts per gram of feces (OPG) from a calf and 1900 OPG from a cow. No cases of clinical coccidiosis were seen in any of the animals sampled during the survey.

Lymphocyte reactivity to Ostertagia ostertagi L3 antigen in type I ostertagiasis.

To better understand the immune response of calves infected with Ostertagia ostertagi, studies were conducted to examine cell-mediated immune responses to L3 antigen and phytohemagglutinin (PHA) by lymphocyte reactivity assay. The L3 antigen was prepared by freeze-thawing and sonication of exsheathed O ostertagi L3. Antigen preparations contained 40 to 60 micrograms of protein/ml and no detectable endotoxin. Cell-mediated immune responses of peripheral blood lymphocytes were determined in 3 groups of 12 calves each: (i) calves given consecutive multiple dose inoculations with L3; (ii) noninfected controls. Consecutive multiple-dose-inoculated calves showed marked increases in stimulation indices (SI) to L3 antigen over the SI of naturally inoculated calves (56.5 and 25.8, respectively). Negative SI were obtained in calves of the noninoculated control group (-1.0). No significant difference (P greater than or equal to 0.05) in response to PHA was obtained between lymphocytes from calves inoculated with O ostertagi and lymphocytes obtained from noninoculated control calves. There was significant (P less than or equal to 0.01) agreement between positive SI and evidence of patent infection (development of type I ostertagiasis). Specificity of lymphocyte reactivity was determined, using lymphocytes from 4 O ostertagi- and 2 Cooperia punctata-infected calves after challenge inoculation. Positive SI to L3 antigen were obtained, using lymphocytes from either O ostertagi- or C punctata-infected calves, indicating that there may be a lack of genus specificity for O ostertagi L3 antigen in lymphocyte reactivity assay. Kinetic studies of lymphocyte reactivity to L3 antigen and PHA showed that responses were briefly suppressed to both of these stimuli in prepatent calves.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of fenbendazole against tapeworms in calves.

Forty-five commercial-grade Angus calves naturally infected with tapeworms (Moniezia sp) were used in 2 controlled experiments to evaluate the cestocidal efficacy of 3 dosage levels of fenbendazole, methyl-5-(phenylthio) -2-benzimidazolecarbamate. In the 1st trial, 15 calves were divided into 3 groups of 5 each. One group served as nonmedicated controls. Other groups were drenched with fenbendazole at dosage rates of 10 and 15 mg/kg of body weight. Thirty calves used in the 2nd experiment were divided into 3 equal groups. One group served as nonmedicated controls and the other 2 groups were drenched at dosage rates of 7.5 and 10 mg/kg. Calves were necropsied 13 days after treatment. Doses of 10 and 15 mg/kg were 100% efficacious in reducing the number of tapeworm scolices, and a dose of 7.5 mg/kg was 91.7% effective. Signs of toxicosis were not observed in medicated cattle from time of treatment to necropsy.

Anthelmintic efficacy of febantel against gastrointestinal helminths in calves.

Three dosage levels of febantel were tested for anthelmintic activities in calves under field conditions. A total of 20 feeder calves affected with naturally occurring gastrointestinal parasites were used in the controlled test. The calves were allotted to 4 groups of 5 each on the basis of degree of parasitism, body weight, age, and sex. Calves in groups II through IV were treated with febantel paste formulation at dosage levels of 5, 7.5, and 10 mg/kg of body weight; calves in group I were used as nonmedicated controls. Calves were euthanatized and necropsied 7 days after treatment. Medications were 97% to 100% effective against the adult forms of Haemonchus placei, Trichostrongylus axei, Cooperia pectinata, C oncophora, Nematodirus spathiger, and Oesophagostomum radiatum; 93% to 98% against Ostertagia ostertagi; and 78% to 95% against Trichuris sp. There were no differences in efficacies of the 3 dosage levels used against adult worms. Efficacy varied from 61% to 96% against larvae of O ostertagi. Activity was not detected against the tapeworm Moniezia benedeni. Medicated cattle did not show signs of intoxication.

Effect of an anthelmintic program with morantel tartrate on the performance of beef cattle.

A field trial was conducted to determine (1) the effectiveness of an anthelmintic program using morantel tartrate (MT) to control subclinical gastrointestinal parasitism among cattle on pasture and (2) the effects of the program on the performance of cattle. Two Hereford herds, each on a separate pasture with forage of comparable quality and quantity, were used. A stocking rate of .62 ha/cow-calf was maintained in both pastures. One herd consisted of 124 cows and 122 calves and served as a non-mediated control group. The second herd consisted of 126 cows and 124 calves. Cows and calves from the latter group were treated with a bolus formulation of MT at a dosage of 10 mg/kg body weight at the beginning of the trial and again 55 d later. Calves were treated again 42 d after the second treatment. Cattle were weighed individually each month and rectal fecal samples for nematode egg counts were obtained from 36 cows and 36 calves from each group at that time. These donor cattle were selected at random at the time of the first weighing; fecal samples were then obtained from the same animals throughout the study. Eggs of the Cooperia-Ostertagia-Trichostrongylus complex predominated in all fecal samplings. There was no difference in the number of nematode eggs from the two groups of cows. However, the medicated cows gained significantly more weight than the controls and had an average weight gain advantage of 28.8 kg. The medicated calves had significantly lower average egg counts and made higher weight gains than the unmedicated calves. The medicated calves had an average weight gain advantage over the control group of 11.1 kg.

Effects of level of nitrogen fertilization of fescue pasture on gastrointestinal parasitism of beef cattle.

Two established tall fescue pastures were used in a 4-year study of the relationship between the level of gastrointestinal parasitism in cattle and the level of nitrogen fertilization of the pasture. One pasture was fertilized with 224 kg of NH4NO3/ha each year and served as the control. A second pasture, referred to as the low-fertilized (LF) pasture, was fertilized with N at 84 kg/ha the first year and 74 kg/ha in each of the next 3 years. Both pastures were stocked with Angus cows (2.5/ha) and their calves. Rectal fecal samples obtained every 6 weeks from 10 cows and as many calves as possible in each pasture were examined for nemotode eggs and coccidia oocysts. Two calves from each group were slaughtered at the end of each of the last 3 years to determine the numbers and species of parasites. Cows had significantly lower egg counts than did the calves. Egg counts did not differ between the two groups of cows, but the control cows had higher average weights than the cows on the LF pasture. Control calves had significantly lower egg counts than the calves on the LF pasture, but only slightly higher mean adjusted 205-day weights. At necropsy, significantly fewer worms were recovered from the controls (17,977) than from the LF-pastured calves (52,332). Cooperia oncophora was the predominant species. The level of coccidia infection did not differ between the two groups of cows and calves. The greater availability of forage in the control than in the LF pasture probably was responsible for the lower level of parasitism in the control calves and for the greater weight gains made by the control cows and calves.

Cestocidal activity of albendazole in calves.

Sixty commercial-grade calves naturally infected with tapeworms (Moniezia benedeni and M expansa) were used in a controlled experiment to evaluate the anthelmintic efficacy of 4 dose levels of albendazole. Calves were randomly divided into 5 groups of 12 each. One group served as non-medicated controls. Other groups were drenched with albendazole (methyl [5-(propyltion)-1H-benzimidazol-2-yl] carbamate) at dose rates of 20, 10, 5 and 2.5 mg/kg of body weight. Calves were necropsied 14 days after treatment. Doses of 20 and 10 mg/kg were 100% efficacious in reducing the number of tapeworm scolices, and doses of 5 and 2.5 mg/kg were 97.8%. Medicated cattle did not show signs of intoxication.

Anthelmintic treatment of subclinical parasitism of feedlot cattle in Georgia.

Forty heifer calves, 27 yearling heifers, and 64 yearling steers with naturally occurring infections of nematode parasites were treated with levamisole HCl or morantel tartrate or were not treated. Although heifer calves had much larger worm egg counts before treatment than yearling heifers, necropsies showed a smaller average number of nematodes in the calves. Both anthelmintics significantly reduced the egg counts. At the end of the experiments, 98 to 240 days after treatments, there was no significant difference among groups of cattle in respect to necropsy worm counts. An advantage of 5% in rate of gain in body weight was shown in each experiment or phase of an experiment in favor of the treated groups of cattle. Overall, an advantage of 6% in feed efficiency was calculated for the treated groups of cattle.

Occurrence of gastrointestinal parasites in Georgia cattle.

A survey of gastrointestinal nematodes in Georgia cattle was conducted from 1968 through 1973 from actual worm counts from viscera of 145 slaughtered beef cattle or from egg counts made from fecal samples from 3,273 beef and 100 dairy cattle. Beef cattle were grouped as calves, yearlings, and cows. Dairy cattle were grouped as calves, replacement heifers, and cows. Results of fecal examinations positive; 99.5, 99.3, 99.6, and 41.2% of the calves, yearlings, drylot calves, and cows, respectively, were infected with nematodes. Seventy-four percent of the eggs counted were of the Cooperia-Ostertagia - Trichostrongylus complex (C-O-T) and 21% were of the Haemonchus-Oesophagostomum complex (H-O). Sixty-nine percent of the infective larvae recovered from coprocultures made from composite samples were of Ostertagia ostertagi. Moniezia (tapeworm) eggs were seen in 16% of all the samples, more predominantly in the calves (24%) and less in the cows (smaller than 1%). Oocysts of Eimeria spp were detected in 61% of the cattle, more predominantly in younger cattle. All cattle necropsied were infected with O ostertagi. Other nematodes present, in order of decreasing frequency, were Trichostrongylus axei (97%), Haemonchus placei (66%), Cooperia punctata (63%), Cooperia oncophora (61%), Oesophagostomum radiatum (61%), Bunostomum phlebotomum (55%), Trichostrongylus colubriformis (36%), Cooperia pectinata (28%), Trichuris spp (17%), Nematodirus spathiger (9%), and Capillaria bovis (4%). Tapeworms were also recovered from 19% of the cattle at necropsy. Seventy-eight percent of the dairy cattle were positive; 98% of the calves, 80% of the heifers, and 58% of the cows. Cooperia-Ostertagia-Trichostrongylus eggs were detected in 78% and H-O eggs in 38% of the cattle. Eimeria oocysts were detected in 71% of all the dairy cattle, and Moniezia eggs were in 10% of the calves and 7% of the heifers.