Production, parasitological and carcase evaluation studies in steers exposed to trichostrongyle infection and treated with a morantel bolus or fenbendazole in two consecutive grazing seasons

Friesian steers were exposed to natural trichostrongyle infection and left untreated (controls) or treated with either a morantel sustained release bolus or fenbendazole at two week intervals (clean) in each of two consecutive grazing seasons. In the second grazing season the mean liveweight gains of the clean, morantel treated and control groups of cattle over 152 days were 105, 131 and 109 kg respectively (morantel treated greater than clean, control P less than 0.02). The cattle were slaughtered following an indoor fattening period. The dressed carcase weight, killing out percentage and related carcase measurements were superior in the treated groups. Eighty per cent of the clean and morantel treated cattle graded satisfactorily and qualified for subsidy payment whereas less than 30 per cent of the control cattle were successful. Rib joint analyses showed significantly lower total weight, eye muscle weight and area together with a higher bone content in control cattle.     

Efficacy of macrocyclic lactones for the control of larvae of the Old World screw-worm fly (Chrysomya bezziana)

OBJECTIVE: To assess the efficacy of four macrocyclic lactones for the control of larvae of the Old World Screw-worm Fly (OWS), Chrysomya bezziana, and to examine the effects of excreted residues on the dung fauna. ANIMALS: 100 heifers were divided into five groups of 20 animals. One group remained untreated, whereas the other groups were treated respectively with pour-on formulations of moxidectin, eprinomectin or doramectin, or a sustained-release bolus of ivermectin. PROCEDURES: At intervals of 1 to 15 weeks after treatment, five cattle from each group were challenged with newly-laid eggs of OWS. The efficacy of each treatment was determined 48 h later by comparing the number of myiases in the treated and untreated groups. Abundance of fly larvae in naturally-voided dung pads and the survival of a species of dung beetle, Onthophagus sagittarius, were used to assess the effects of drug residues on the dung fauna. RESULTS AND CONCLUSIONS: Moxidectin showed no activity against larvae of OWS during the first 14 days after treatment. Eprinomectin provided protection for 3 days after dosing, but failed at days 7 and 14, whereas doramectin was effective at day 7, but not at days 14 or 21. In contrast, no myiases were established on bolus-treated cattle from 14 to 102 days after treatment. Faecal residues of moxidectin had no effect on the survival of larvae of dung-feeding flies, whereas those of eprinomectin and doramectin reduced survival for 1 to 2 weeks. Dung voided by bolus-treated cattle inhibited fly breeding and had adverse effects on the development and survival of O sagittarius for up to 15 weeks after treatment.     

Response of Trypanosoma vivax and Trypanosoma congolense in zebu cattle in North Cameroon to prophylactic treatment with two formulations of isometamidium

We tested the efficacy of two formulations of isometamidium in a tsetse-infested farm in North Cameroon from 20 August 2000 to 5 January 2001. A total of 90 adult cattle were used in three groups of 30 each corresponding to two treated and one untreated control. Drug efficacies were evaluated in terms of reduction of parasite incidence in the host's blood, maintenance of packed-cell volume (PCV) and weight gains. Both drugs reduced the incidence of parasites even though re-infections 2 weeks after treatment were common. PCV values were similar in both treated groups but higher than in the untreated control. Body weight changes followed a similar trend with the control losing weight from a mean of 427+/-119kg at the beginning to 398+/-93kg in 4 months. Weights increased from 375+/-76 and 396+/-110 to 396+/-69 and 418+/-112kg in the Veridium and Trypamidium groups, respectively. Efficacy was similar between the two formulations of isometamidium in the prophylaxis of bovine trypanosomosis. However, the presence of parasites in some animals barely 2 weeks after treatment suggested that either infections were not cleared or residual drug effects were not sufficient to prevent re-infections.     

The efficacy of diazinon impregnated ear tags against buffalo fly and resulting weight gains and diazinon residues in meat and milk

Ear tags impregnated with 20% diazinon were evaluated for their efficacy against the buffalo fly (Haematobia irritans exigua) on beef cattle in southern Queensland. Buffalo fly numbers and weight changes were recorded and diazinon residues in tissues of beef cattle and milk from lactating dairy cattle were assayed at different time intervals after tagging. In 2 efficacy trials conducted over 19 and 20 weeks, the mean numbers of buffalo fly on cattle each fitted with ear tags were 1 to 9 and 0 to 16, respectively, in trials 1 and 2, compared with 44 to 345 and 26 to 306 per head on untreated herds, respectively, despite regular spraying of the untreated herd in trial 1 with cyper-methrin to reduce fly burdens. Percentage buffalo fly control was 96.7 to 99.5% and 89.3 to 100% in the 2 trials. Cattle fitted with ear tags gained an average of 94 kg body weight after 5 months compared with 61 kg in the untreated herd, a net increase of 60% in treated animals compared with 28% in the untreated herd. Mean diazinon residue concentrations in the fat of perianal tissue biopsies were 0.02 to 0.03 mg/kg 1 to 8 weeks after tagging. Mean diazinon residue concentrations in the butterfat of milk from lactating dairy cattle were 0.01 to 0.04 mg/kg after tagging.     

Efficacy of doramectin 0.5% w/v Pour-On for control of the horn fly, Haematobia irritans

In 1998, three groups of cattle at three locations in Lousiana were treated with Dectomax^® (0.5% doramectin) Pour-On and horn fly populations were monitored. Acceptable levels (less than 50 flies per side) of horn fly control were observed from 4 to 8 weeks. Differences in the length of control among the three sites were most likely affected by immigration of adult flies from untreated groups. In 1999, acceptable horn fly control was obtained for 13 weeks by the use of two treatments of doramectin Pour-On.     

A field trial to evaluate the efficacy of a combined rotavirus-coronavirus/Escherichia coli vaccine in dairy cattle.

A field trial was designed to determine the efficacy of a combination rotavirus-coronavirus/Escherichia coli vaccine on dairy farms in southwestern Ontario. In Part A of the trial, 321 cows on 15 farms were randomly assigned to either vaccination or placebo groups. On eight farms, 50% of the dams were vaccinated, while on the other seven farms, 80% of the dams were vaccinated. In Part B of the trial, 26 farms were randomly assigned to either a total vaccination program or to no vaccination program. Mortality, disease occurrence and weight gains were recorded on all calves for the first two weeks of life. In Part A, 23.5% of all calves were treated in the first two weeks of life, 20.9% were treated specifically for scours and 3.6% of live-born calves died. Enteropathogenic E. coli was identified on 13 of the 15 farms, rotavirus on 11 and coronavirus on ten. At least one of the three potential pathogens was found on every farm. There were no significant differences between calves from placebo-treated and vaccine-treated dams with regard to the proportion treated for all diseases, or for scours, or the proportion which died. Neither were there differences in days to first treatment for all diseases (seven days on average), days to first scour (6.7 days), duration of treatments (3.9 days for all diseases, 3.7 days for scours), or estimated weight gains (0.5 kg/day to 14 days). These results were not altered when the presence or absence of enteropathogenic E. coli, rotavirus or coronavirus on the premises was accounted for.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experiments on anthelmintic control of Fasciola hepatica in Brazil.

Two separate field trials involving naturally infected cattle were carried out on two farms known to have a history of Fasciola hepatica infection. On the first farm, 15 animals per group were allocated as follows: G1, triclabendazole (TCBZ) four times a year; G2, TCBZ twice a year (May and September); G3, untreated control. All groups grazed together and after 3.5 years the animals were slaughtered and their livers examined by federal meat inspectors who condemned 100% of livers in G3 and 8.3% in G2 owing to the presence of lesions of fasciolosis. In G1 no livers were condemned. Significant differences in weight gains were not detected and fluke counts remained at low levels in the treated groups. Also, in the control group, egg counts started to decrease when animals were 2 years old. On the second farm, groups of 20 animals were treated as follows: G1, TCBZ three times a year (May, September and December); G2, TCBZ twice a year (May and September); G3, nitroxynil twice a year (May and September); G4, rafoxanide twice a year (May and September); G5, untreated controls. All animals were weighed and faecal samples examined at approximately 28-day intervals. During the period of the study, larger weight gains were detected in the TCBZ treated groups than in the others. TCBZ treatment kept F. hepatica egg counts at a lower level for longer periods than the other drugs and significant differences in weight gains were only obtained between the group receiving TCBZ three times a year and the control group.     

Effect of a single dry season anthelmintic treatment of N'Dama cattle on communal pastures in The Gambia

The effect of a single anthelmintic treatment of cattle during the early dry season was studied. One hundred and sixty-six N'Dama cattle, 1–3 years old, were selected from five herds. There were 65 males and 101 females divided into two groups of 83 animals each. One group was treated with fenbendazole at 7.5 mg/kg body weight by mouth in November 1992; the other group remained as the untreated control. At monthly intervals from November 1992 to April 1993, each animal was weighed and the number of eggs/g of faeces (epg) was determined. The infective larvae (L3) were examined following culture of pooled samples from each group of animals. In April 1993, 6 animals (3 treated and 3 controls) from the herds under study were necropsied. The difference in the weight gains (4.6 kg) of the two groups was highly significant (p<0.0001). The difference in the weight gains and the epg between the treated and control groups was influenced by the age of the animals. Of the treated animals, one contained no nematodes, one contained only 25Oesophagostomum radiatum, and the third contained 25Cooperia L4. The three untreated animals were all infected. It was concluded that the treatment in early dry season, with an anthelmintic effective against both adults and larvae, led to a significant reduction in egg counts, to elimination of adults and hypobiotic larvae and, consequently, to an increase in the body weight gain by the treated animals.     

Effects of tick infestation on Boran (Bos indicus) cattle immunised against theileriosis in an endemic area of Kenya

Boran (Bos indicus) heifers were immunised by infection with local Theileria parva parva, T p lawrencei and T mutans stocks and treated with parvaquone and later exposed to natural tick and tick-borne disease challenge in the Trans-Mara Division of Kenya. The Theileria species parasites in the challenge were maintained in African buffalo and cattle and the tick vectors were supported by several species of wild Bovidae and domestic livestock present in the area. Thirty immune cattle were observed for 30 weeks while grazing on a ranch in the Trans-Mara Division. Of these, 15 were immersed in toxaphene at weekly or twice-weekly intervals while 15 cattle remained without acaricide application. Cattle which became pregnant were withdrawn from the experiment. There was no evidence of any clinical tick-borne disease in either group of cattle during the experiment. Five species of ixodid ticks infested the cattle during the experiment and cattle which were not treated with acaricide had far more ticks. Rhipicephalus appendiculatus was the most abundant tick species, with a mean infestation of 46 adults per animal in the undipped cattle. This tick also appeared to be the cause of the observed reduction in weight gains. Major haematological parameters did not differ significantly between the groups. Behavioural studies showed that the undipped cattle spent less time grazing and ruminating. This study has shown that, at the expense of some loss in productivity, zebu cattle, immunised against ticks and theileriosis, can be kept despite tick infestation.     

The efficacy of triclabendazole (Fasinex) against immature and adult Fasciola hepatica in experimentally infected cattle

Eighteen Chinese cattle were experimentally infected with metacercariae of Fasciola hepatica and randomly assigned to 6 groups. Five groups of cattle were treated with a single oral dose of triclabendazole at a dose rate of 12 mg kg-1. At necropsy, the reduction in fluke burden compared with the untreated group was 85, 99.6, 99.8, 100 and 100% for cattle treated 2, 6, 8, 12 and 16 weeks after infection, respectively. Data are also presented on body weight changes during the experimental period and on serum gamma-GT activity in cattle from selected groups. Triclabendazole is considered to be safer and more efficacious than currently available fasciolicides in China.     

EFFECT OF SUBCUTANEOUS IMPLANTS OF ZERANOL ON WEIGHT GAINS OF CASTRATED CATTLE AT PASTURE†

SUMMARY Eight experiments involving a total of 480 castrated cattle grazing Australian pastures were conducted to assess the effect of subcutaneous implants of 36 mg zeranol on weight gain. A wide range of cattle ages, bodyweights and environmental and nutritional conditions was involved. Growth rates of untreated cattle ranged from minus 0.15 kg/day over 90 days to 1.23 kg/day over 52 days. In 5 experiments treated cattle were implanted at the commencement of the experiment only. The other 3 experiments compared responses to early, late and early plus late implantation. Weight gains from a single implantation ranged from 4.6 kg over 70 days to 16.8 kg over 60 days—an average increase in growth rate of 13.5%. Repeating implantation at a later date increased growth rate further and provided greater gains than a single implantation whether applied early or late. Carcase weights were measured in 2 experiments. In one, weight was increased by 7.2 kg (P < 0.01). In the other, cattle in both implanted and control groups lost weight over the duration of the experiment. Whilst the bodyweight of implanted cattle was less than that of untreated cattle the carcase weight of implanted cattle was 2.4 kg greater than for control cattle. Neither of these differences was significant (P > 0.10). No side effects were noted in any of the treated cattle.     

The application of moxidectin formulations for control of the cattle tick (Boophilus microplus) under Queensland field conditions

Objective To assess the control of the cattle tick (Boophilus microplus) and the performance of commercial cattle treated with the macrocylic lactone endectocide, moxidectin, formulated either as an injection or as a pour-on. Design Groups of 10–12 tick infested cattle were treated with moxidectin injection, moxidectin pour-on or remained untreated (28-day trials) or were treated with deltamethrinethion as a dip (140-day trials). The cattle were exposed to natural tick challenge under field conditions. Procedure Tick numbers on trial cattle were recorded in each trial before the initial treatment and in the 28-day trials at 7, 14, 21 and 28 days or in the 140-day trials, at 28-day intervals before each of the treatments and at the final inspection. Body weights of the cattle were also recorded prior to the initial treatment and at the termination of each trial. Cattle were observed on the day of each treatment and at each inspection for evidence of any reactions to treatment. Results 28-day trials: Significant reductions in tick counts were recorded in both treatment groups when compared with cattle in the untreated group. Weight advantage was recorded in the moxidectin treated groups. 140-day trials: All three treatments resulted in zero or low tick counts at each inspection with the exception of the pour-on treatment at week 8 in one trial and week 9 in the other trial. Additional weight gain was recorded for both the moxidectin treated groups, relative to the deltamethrin-ethion dip groups, but was significant only for the pour-on groups. There was no evidence of any local or systemic adverse reaction in any treated cattle in any trial. Conclusion Good to excellent control of the cattle tick (Boophilus microplus) was demonstrated with the moxidectin formulations in all trials, the injection being particularly effective. An improved performance was recorded in all trials in cattle treated with both moxidectin formulations when compared with the untreated cattle and with cattle treated with the deltamethrin-ethion dip. There was no evidence of any local or systemic adverse reaction to treatment with either moxidectin formulation.     

ANTHELMINTIC TREATMENT OF YOUNG BEEF CATTLE IN THE WALLUM REGION OF SOUTH-EASTERN QUEENSLAND

An anthelmintic treatment trial on 125 Brahman-British crossbred 2 to 4 month old calves was undertaken on Wallum country in south eastern Queesland. The calves were divided into 5 experimental groups, grazed together and treated as follows for 17 months: Group 1--Untreated controls; Group 2--Monthly levamisole--niclosamide on 4 occasions; Group 3--Monthly levamisole until 1 month after weaning; Group 4--Levamisole 3 to 6 weeks after saturating rains; Group 5--No levamisole--niclosamide as for Group 2. The mean body weight gains for cattle in Groups 1 to 5 were 95, 124, 105, 121 and 97 kg respectively. Four cattle were lost from each of Groups 1 and 3 and five from Group 5. Most of these losses occurred towards the end of the second summer rainfall season. Faecal egg count maxima were recorded around weaning in untreated groups and during the summer rainfall period of both the first and second summer in all groups. The most prevalent nematode species encountered were H. placei, Cooperia spp and O. ostertagi. It is recommended that in this region cattle under 2 years of age should receive anthelmintic treatment at least in autumn and spring.     

The effect of East Coast fever immunisation and different acaricidal treatments on the productivity of beef cattle

A trial was performed on a farm in the Coast Province of Kenya to study the effects of East Coast fever immunisation and different acaricidal treatments on the productivity of immunised and unimmunised beef cattle. Eighty cattle were immunised against Theileria parva parva (Marikebuni) by the infection and treatment method and a similar group was left as an unimmunised control. Immunisation had no deleterious effect on the cattle. After immunisation, the immunised and control groups were each subdivided into four groups of 20 and each subgroup was managed under a different tick control regimen. The tick control regimen were, acaricidal spraying twice a week or once every three weeks, the application of acaricide-impregnated ear-tags, and no tick control. During a nine-month exposure period there were 18 cases of East Coast fever among the 80 immunised cattle, three which were severe and the others mild. Among the 80 unimmunised cattle there were 57 cases of East Coast fever, 50 of which were severe. The highest morbidity and mortality occurred in the groups under limited tick control or without tick control. Overall weight gain in the immunised cattle, irrespective of the tick control regimen, was better than the weight gain in the unimmunised groups. Within the immunised groups, the weight gain of the cattle sprayed twice weekly was comparable to the weight gain of the animals with acaricidal ear-tags and was significantly higher than the weight gains in the groups sprayed once every three weeks or with tick control. Preliminary cost/benefit analysis showed that it was uneconomical to maintain unimmunised cattle under limited or no tick control.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of replacing fishmeal with black soldier fly larval meal in the diets of grower-finishing guinea fowls reared under tropical conditions

The study was conducted with the view to determine the impact of replacing fishmeal with black soldier fly larval meal (BSFLM) on growing guinea fowls. BSFLM replaced fishmeal (3% in the control diet) in the ratios of 0, 20, 40, 60, 80, and 100% to produce six dietary treatments, which were iso-caloric and iso-nitrogenous. Two hundred and forty-eight-week old guinea fowls with mean live weight of 273.2?±?10.9 g were tagged, weighted, and randomly assigned to 24 (6?×?4) floor pens; each pen was treated as a replicate. Feed and water were provided ad libitum during the entire period, which lasted 10 weeks. Feed consumption differed among the treatment groups (P?=?0.0072) with the 100% fishmeal diets recording the lowest. Daily gain was significantly (P?=?0.009) higher for birds fed high BSFLM diets compared to the control (100% fishmeal diet). The inclusion of BSFLM in the diets elicited positive linear effect on weight gains of the guinea fowls (R²?=?0.91) with increasing concentration resulting in higher live weight gains. The feed conversion ratio (FCR) also differed between treatments (P?<?0.05) but similar for the 100% fishmeal (control) and 100% BSFLM diets. Organ and haematopoitic integrity were equally assured regardless of levels of the protein sources fed to the birds. Generally, meats from birds fed 60 to 100% BSFLM and from hens were more acceptable. A study to evaluate the economics of utilising BSFLM in guinea fowl production is recommended.     

The effects of anthelmintic treatments against gastrointestinal nematodes on the performance of breeding ewes and lambs on pasture in semi-arid Kenya

The effects of anthelmintics treatments in controlling gastrointestinal nematodes in breeding ewes in a semi-arid area of Kenya were determined. The study carried out during two breeding seasons, between June 2000 and December 2001 where albendazole was administered to groups of ewes, 2 weeks before mating, 3 weeks to lambing and mid lactation indicated significantly lower nematode egg counts in treated than untreated groups of ewes. In the first breeding season, reduced rainfall resulted in pasture scarcity and weight loss in both groups of ewes through out the gestation period, but losses were higher for the untreated group. In the second season, both groups of ewes showed a steady increase in weight gain during the gestation period and post-partum, but weight gains were higher in the treated group. In lambs, weight gains at 6 weeks were higher for treated ewes than control groups, in both breeding seasons. The results of this trial indicate that anthelmintic treatments in breeding ewes in the study area are beneficial in reducing gastrointestinal nematode infections and improving performance of the ewes and their lambs. In addition to the treatments, breeding ewes should be given feed supplementation particularly during periods of pasture scarcity.     

Effects of residues of deltamethrin in cattle faeces on the development and survival of three species of dungbreeding insect

Objective To assess the toxicity to insects of drug residues excreted in cattle faeces following treatment with deltamethrin.
Design Bioassays were performed on one species of dung-breeding fly ( Musca vetustissima ) and two species of dung beetle ( Onthophagus binodis and Euoniticellus fulvus ).
Animals Cattle on properties near Kangaroo Valley, Canberra and Gundagai were treated with pour-on formulations of deltamethrin. Untreated animals acted as controls.
Procedures Faeces from treated and untreated cattle were inoculated with newly emerged fly larvae or fed to adults of two species of dung beetle. Percentage survival and duration of development provided measures of the toxicity of deltamethrin residues in faeces.
Results Residues of deltamethrin were excreted in concentrations sufficient to inhibit survival of larvae of M vetustissima for 1 to 2 weeks after treatment. Peak concentrations of 0.4mg deltamethrin/kg dry weight of faeces occurred 3 days after treatment and were sufficient to kill adult beetles for at least twice this period. With one of two formulations tested, there was evidence of a reduction in dung beetle fecundity and an increase in the duration of juvenile development. A model of the effect of deltamethrin on the breeding success of dung beetles in the field suggests that a single treatment, applied when most of the population is in a non-parous condition, may cause up to 75% reduction in beetle acitivity by the end of the season. Multiple treatments at 10 or 21 day intervals may drive local populations towards extinction.
Conclusion Depending on the time and frequency of treatment, the effect of deltamethrin on insects in cattle faeces may range from negligible to catastrophic.     

Clinical and parasitological evaluations of levamisole as a treatment for bovine stephanofilariasis

Field trials were carried out with two formulations of levamisole for treatment of chronic inflammatory lesions on the muzzle and teats of cattle, caused by Stephanofilaria okinawaensis in the enzootic area of the disease, Ishigaki Island, Okinawa Prefecture, Japan.Cattle were treated orally with levamisole hydrochloride (10% powder) at a dose of 7.5 g/100 kg of body weight once (64 cattle) or twice with an interval of 3 or 4 weeks (five cattle each). Lesions on the muzzle and tests disappeared or were reduced within 4 weeks of the first medication. In some cattle a sign of recurrence was observed 8 weeks after medication.Parasitological and histological examinations were carried out 1 week carried out 1 week (10 cattle), 4 weeks (12 cattle), and 8 weeks (13 cattle) after single oral administration of levamisole hydrochloride. No Stephanofilaria worms were detected at 1 week after medication. A small number of worms were detected at 4 weeks and more were observed 8 weeks after medication.A levamisole phosphate solution (18.2%) was injected subcutaneously once into one teat of each of three cattle, or twice into the neck with a 4-week interval between treatments (five cattle). The dose was 2 ml/teat (364 mg of active ingredient) or 2 ml/45 kg of body weight for the side of the neck. There was marked improvement as with oral medication with levamisole hydrochloride powder.     

Comparative evaluation of two ivermectin injectable formulations against psoroptic mange in feedlot cattle

A study was carried out to compare the efficacy of two injectable formulations of ivermectin, Ivomec,(1) Merial (IVM reference) and Ivogell,(2) Intervet (IVM generic) in the treatment of psoroptic mange (Psoroptes ovis) in Charollais feedlot cattle. A total of 22 animals were ranked in order of the severity of mange and allocated to 11 replicates of 2 animals each. Within each replicate, one animal was randomly allocated to IVM reference product treatment (Group 1) and one to IVM generic (Group 2). Animals were treated on Day 0 and on Day 8 at the recommended dosage of 200 microg ivermectin/kg bodyweight. The pharmacokinetics profiles (pK) of both IVM formulations were evaluated in plasma samples taken from 6 cattle randomly chosen per group on Day 0, before treatment, and then at 6, 12, 24 hours and daily from Day 2 to Day 7 after the treatment on Day 0. Additionally, the severity of mange lesions was assessed and mites were counted in skin scrapings on Days 0, 8, 15 and 25. Animals were weighed on Day 0 and 25 and body weight and average daily gains (ADG) were evaluated. No statistical differences were found between the cattle of the two groups in any pK parameters, although the mean IVM plasma concentrations in cattle treated with the IVM reference product were consistently higher than those found in cattle treated with the generic compound. By Day 25, all animals in Group 1 had recovered clinically and parasitologically from psoroptic mange while cattle from Group 2 still had mange lesions and, in two animals, living mites were found in the skin scrapings; these differences were significant (P<0.001). The mean body weight of the two groups was significantly different on Day 25 (P<0.01) when animals in Group 1 weighed 20 kg more than those in Group 2. In conclusion, despite similarities in their pharmacokinetic profiles and formulations, the clinical efficacy of the two injectable formulations of IVM differed significantly in their therapeutic efficacy against psoroptic mange in feedlot cattle up to 25 days after treatment: this difference in response was reflected in an incomplete clinical and parasitological response in Group 2 and a slower growth rate.     

ANTHELMINTIC TREATMENT OF YOUNG BEEF CATTLE IN CENTRAL QUEENSLAND

The value of regular anthelmintic treatment of beef calves was assessed in two herds in central Queensland. In each herd groups of 31 suckling calves were observed. Control groups received no treatment, and treated groups received injectable trichlorphon either after rainfall exceeding 2 inches or monthly. Regular faecal egg counts revealed moderate infestations with Haemonchus placei, Oesopha-gostomum radiation, Cooperia spp, and Tricha-strongylus spp. In one herd, the groups received 0, 7, and 14 treatments over a period of 15 months, and showed mean weight gains of 356, 355, and 365 lb respectively. In the second herd after 0, 6, and 12 treatments, the corresponding gains were 407, 415, and 419 lb. It was concluded that, in these circumstances, the anthelmintic treatment had no economic value.