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.     

REPRODUCTIVE PERFORMANCE OF BEEF CATTLE IN NORTHWESTERN QUEENSLAND

The reproductive performance of beef cattle in 5 herds mated all year round in north-west Queensland was examined from 1970 to 1973. Conception rates, conception patterns and branding rates were used to assess annual reproductive performance. The level of loss between the times of confirmed pregnancy and branding was defined. The mean annual conception rate was 83.1% with individual property means ranging from 75.4 to 90.9%. Conception rates for heifers, first calf cows and mature cows were 83.9%, 80.6% and 84.7% respectively. Conception patterns were influenced by seasonal conditions, 68.1% of conceptions occurring in the wet season, between December and May. In this region, conception patterns were highly correlated with rainfall during the previous month. Losses between the times of confirmed pregnancy and branding ranged from 5.9 to 27.7%. Body condition of animals varied and was dependent upon lactation, seasonal and parity effects.     

A SURVEY OF DYSTOCIA IN BEEF CATTLE IN SOUTHERN QUEENSLAND

Data relating to dystocia were obtained for 22% of beef herds in the Roma region of southern Queensland. In 1973 dystocia incidence in 23,129 maiden heifers was 12%; 4% of heifers and 7% of calves died. Thirty-five per cent of the 444 herds surveyed had more than a 10% incidence of dystocia, and 10% had more than a 30% incidence of dystocia. Only 6% of herds had no dystocia. Among the 73% of producers considering dystocia a problem in most years, 14% regarded it as a major problem. The incidence of dystocia in heifers was significantly higher in Poll Hereford than Hereford herds, which in turn were higher than other breeds of cattle. Poll Hereford and Hereford owners were the most concerned about dystocia but did not supervise calving more frequently. Dystocia and attitude were also examined in relation to degree of supervision at calving and size of the breeding herd.     

EPIDEMIOLOGY OF HELMINTH INFESTATION OF BEEF CATTLE IN CENTRAL QUEENSLAND

The results of epidemiological studies of helminths in young beef cattle in Central Queensland over a 2½-year period commencing in January 1964 are reported. Studies were made on ten beef cattle properties, which have a total annual calf crop of approximately 2500 calves. Twenty-five faecal samples were collected monthly at random from 30 to 40 permanently identified calves on each property, to determine the types and intensity of helminth infections. Although rainfall was well below average, infections with most of the helminth species commonly found in Queensland were detected. Increases in infection levels occurred, after rainfall of two inches or more, in animals up to 21 months of age. Only on a property where pastures were irrigated and the stocking rate was higher than normal for the area did a high percentage of calves show clinical symptoms of parasitic gastroenteritis. Haemonchus placet and Oesophagostomum radiatum were the predominant species. An immunity developed to O. radiatum during the first 12 to 15 months of the calf's life. The immunity to H. placet was variable with some animals susceptible to re-infection up to 21 months of age. Recommendations for the control of helminths in beef cattle in this area are given.     

A STUDY OF NEPHRITIS OF BEEF CATTLE IN NORTH QUEENSLAND

The incidence of subclinical nephritis in beef cattle slaughtered at a Townsville abattoir during the period 1970-73 was 3.8 percent. A rising incidence coincided with the wet summer of 1973-74 reaching a peak of 8.2 percent thereafter in June 1974. All but 1 of 100 cases macroscopically identified as nephritis and studied histologically proved to be of interstitial type in which lymphocytic infiltration predominated. Follicular lymphoid hyperplasia was also a common feature. The exceptional case showed proliferative glomerulonephritis. Leptospires were isolated from 16 percent of cases cultured, and observed in 8 percent of specimens examined histologically. All of the 8 isolates subjected to serogrouping were L. pomona. Of the animals tested serologically against 2 serotypes 66.2 percent were positive to L. pomona (33.8 percent), L. hardjo (18.9 percent) or both (13.5 percent). The total incidence is significantly higher than in other random surveys carried out in the region. These findings suggest that Leptospira sp. are a major cause of bovine nephritis. Since other pathogens endemic in the area, for example, Babesia and Theileria sp., may be capable of causing nephritis in cattle an accurate assessment of the aetiology of that form of renal disease in north Queensland cannot yet be made.     

INFECTION RATES AND OUTBREAKS OF DISEASE DUE TO BABESIA ARGENTINA IN UNVACCINATED CATTLE ON 5 BEEF PROPERTIES IN SOUTH-EASTERN QUEENSLAND

Serums from unvaccinated groups in 5 herds of beef-cattle in South-East Queensland were tested for antibodies to Babesia argentina at intervals while the cattle were increasing in age from about 6 months. An indirect fluorescent antibody test was used. Infection rates, indicating the proportions of the groups that had been exposed to tick-transmitted infection were 49.2, 56.9 and 69.1% for cattle aged approximately 6, 12 and 18 months, respectively. The degree to which cattle were infested with the vector, Boophilus microplus, was estimated. There appeared to be a strong correlation between infection rate and tick incidence. Four serologically negative animals died of either confirmed or suspected babesiosis during the sampling period. Sickness was observed in 5 others. The serological status of 57 changes from negative to positive without symptoms being observed, indicating relatively low mortality and morbidity rates in the enzootic situation studied.     

VACCINATION WITH BABESIA ARGENTINA IN 5 BEEF HERDS IN SOUTH-EASTERN QUEENSLAND

Observations on the use of a vaccine containing Babesia argentina in 5 partly susceptible beef herds in south-eastern Queensland were made on 1,029 female breeding cattle over a period of 4 years. Groups averaging about 20 heifers were given 0, 1, 2 or 3 vaccinations. Incidence derived from groups experiencing clinical attacks were 17.9% for unvaccinated cattle and 1.2% for vaccinates. Increasing the number of vaccinations did not appear to increase protection. The one clinical manifestation of infection with B. bigemina was associated with a concurrent reaction to vaccination with Anaplasma centrale. There were no cases of haemolytic anaemia in new-born calves. No severe reactions followed primary vaccination, but 2 revaccinated animals became sick.