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 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.     

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.     

A PATHOLOGICAL AND BACTERIOLOGICAL STUDY OF THE MAMMARY GLANDS OF BEEF COWS IN NORTH QUEENSLAND

Pathological and bacteriological studies were made of a total of 507 udders from slaughtered beef cows originating from various locations in northern Queensland. Incidence of supernumerary tests was 28%, their distribution being caudal (80%), intercalary (8%), ramal (5%) and anterior 1%; 6% had both caudal and intercalary teats. They were seen most frequency in British breed and British-Brahman crossbreds (each 29%) and less frequently in Brahmans (22%). Gross lesions were found in 11.4% of cows; these lesions comprised cysts (2.8%), leech infestation (1.0%), mastitis (0.6%), teat occlusionsion (3.9%), papillomatosis (1.2%), cutaneous horns (0.4%), teat fistulas (0.4%), teat trauma (0.6%) and udder fibrosis (0.6%). Mastitis was obviously low in occurrence, while leech infestation and teat occlusion were relatively frequent in cows from one area. Bacteriological examination of single quarters in 364 cows, revealed infection in 154 (42.3%). A total of 199 isolations were made of which 3.5% were recognised mastitis pathogens. Pathological conditions were found, and bacterial isolations were made more frequently in aged than in mature or young cows.     

THE DISTRIBUTION OF MYCOBACTERIUM BOVIS IN QUEENSLAND CATTLE HERDS WITH OBSERVATIONS ON THE LABORATORY DIAGNOSIS OF TUBERCULOSIS

SUMMARY Of 1,791 tissues submitted from 1975 to 1978 for histological examination for tuberculosis, 78.5% were classified as tuberculosis, 8.1% as club-forming granulomas, 3.3% as hydatid cysts, 3.4% as other granulomas and 2.4% as squamous cell carcinomas. Cultural examination of 2,682 tissues for mycobacteria yielded Mycobacterium bovis from 42.88%, other mycobacteria from 7.64% and 0.89%Rhodococcus (Corynebacterium) equi. Of 1,478 tissues on which both examinations were performed, culture and histology results were in agreement on 94.1%. M. bovis was isolated on one or more occasions from 564 herds with the highest herd prevalence being recorded in western areas of the state. Culture of 1,024 tissues from no visible lesion (NVL) reactors yielded 0.59%M. bovis, 15.04% other mycobacteria and 0.19%R. equi. Of 120 isolates of other mycobacteria from tissues of NVL reactors, 39 were Runyon Group III (20 M. avium complex) and 61 Runyon Group IV. Approximately half of the herds from which NVL tissues were collected were confirmed M. bovis infected properties.     

A SURVEY OF CLINICAL MASTITIS IN SOUTH-EAST QUEENSLAND DAIRY HERDS

SUMMARY A survey of clinical mastitis in 26 South-East Queensland dairy herds supplying more than 300,000 litres of milk annually, revealed a quarter incidence of 2.6% with a cow incidence of 9% over a 3-month period. Secretion samples from cows yielded Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, Pseudomonas spp and other bacteria in 38.5%, 12.5%, 6.6%, 3.4%, 2.6%. 0.6% and 2.0% of cases respectively. Samples from 38% of the cases were culturally negative while at least 38% of the clinical quarters had shown a previous clinical episode of mastitis. There was a significant association (P < 0.025) between herd and the likelihood of a negative culture result on samples from clinical cases. Twenty-one percent of cases occurred in the first month of lactation and 10.3% in the first week. There was a significant association (P < 0.005) between the age of cow and the stage of lactation in which clinical cases occurred in that cows in the 2 to 5 year age group were more likely to suffer attacks in the earlier part of lactation. There was a highly significant relationship (P < 0.005) between cow age group and the proportion of affected quarters and it was calculated that the change with each year of age was a 55% increase over the previous year. Forty-five percent of the isolates of S. aureus were resistant to penicillin.     

BREEDING PATTERNS IN COMMERCIAL BEEF HERDS

A total of 16,111 cows in 18 beef herds in New South Wales were examined for pregnancy between June 1963 and February 1967. The mean pregnancy level was 86%. The pregnancy level for the lactating cows was 87% and for the non-lactating cows (excluding heifers) 85%. The pregnancy level for heifers was 84%. The herd pregnancy level ranged from 80% to 98%. Four herds had a significantly higher pregnancy level in the lactating cows, while three herds had a significantly higher pregnancy level in the non-lactating cows. Positive Br. abortus agglutination titres were recorded from three herds, none of which had been vaccinated with Strain 19. Br. abortus titres were negative in the remaining 15 herds. One of these herds had practised regular weaner vaccination with Strain 19 at 6–10 months of age. In one of the positive herds a typical abortion storm occurred with 33% of the pregnant cows failing to bring a calf to branding. A follow-up blood test of 65 of the WD cows at calf branding showed 74% with titres 1 in 40 or higher. The mean discrepancy between females pregnant at pregnancy diagnosis and calves branded from these females was 17% for heifers and 3.5% from the older cows. Dystocia was established as the main cause of calf loss in the heifer group.     

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.