THE ECONOMIC EFFICIENCY OF A VETERINARY PREVENTIVE MEDICINE AND MANAGEMENT PROGRAM IN VICTORIAN DAIRY HERDS

SUMMERY: This paper reports the major results of a 4-year controlled study of the impact of a dairy herd health and management program on dairy farms. The aim of the project was to conduct a practical preventive medicine program which could be operated by practising field veterinarians to assess the economic value of the program. The analysis of performance involved 59 program farms which received the program and 47 surveillance farms which did not receive the program. Each group commenced with 80 farms. A comparison of indices reflecting the efficiency of production showed relative gains for program herds when compared to surveillance herds and these differences were significant for the indices of butterfat per hectare (P=.001) and butter fat per man (P=.005) but not for butterfat per cow (P=.455). The indices of financial efficiency showed significant improvements in program farms when compared with surveillance farms in the standardised change in gross margin per hectare (P=.001), per man (P=.003) and per cow (P=.007). On a mean whole-farm basis, the program gave an improvement in gross margin of 23.58, 65.56 and 90.30 per hectare in the second to fourth years respectively of the project when compared with performance in the first year. Mean intercalving intervals were significantly shorter in program than surveillance herds throughout the project (P=.013). The proportion of cows calving within 8 weeks of the start of the calving season increased from 68.5% to 74% in program herds and from 72% to 73% in surveillance herds, but there was no significant difference (P=.101) between groups in this change. The standardised change in bulk milk cell count was greater in program herds than surveillance herds, but the quarter infection prevalence of surveillance herds. which was only measured in the final year of the project, was significantly lower than the prevalence measured at the same time in program herds. It was concluded from this study that the dairy health and management program tested in this study represents a highly profitable investment for dairy farmers.     

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.     

PREGNANCY RATES AND NON-RETURN RATES FOLLOWING ARTIFICIAL AND NATURAL BREEDING IN DAIRY HERDS

SUMMARY Information routinely supplied during the conduct of a dairy herd health program was analysed to evaluate the performance of artificial breeding in Victoria. A comparison was made between 60 to 90-day non-return rates (supplied by artificial breeding centres) and pregnancy rates (determined by manual pregnancy diagnosis) for first artificial inseminations in 108 herd years in which both items were available in the 1973 and 1974 breeding seasons. The values were 69.3% and 58.2% respectively (P <0.001). Non-return rates and conception rates were found to decline as herd size increased. Pregnancy rates to first artificial and natural services did not differ significantly from each other but pregnancy rates were significantly more variable to natural than artificial service (P < 0.001). The mean pregnancy rate to artificial insemination for all herd years studied was 57.5% and the pregnancy rate to natural service was 58.0%.     

OBSERVATIONS OF THE FIRST SERVICE NON-RETURN RATES OF THE HYPOGLYCAEMIC, CONCENTRATE-FED DAIRY HERDS

SUMMARY Fourteen dairy herds which had been subjected to the Compton Metabolic Profile test on a total of 29 occasions were selected from the records of the Institute for Research on Animal Diseases, United Kingdom, because they had a wide range of mean blood-glucose concentrations. Two herds had to be rejected from the study because of inadequate breeding records, leaving 12 herds (26 profile tests) to be included. The first service non-return rate of each herd was calculated from the breeding records of 10 cows mated closest to the date of each profile test. These rates were positively related to the mean blood-glucose concentrations of the lactating cows (P <0.01).