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Bovine Venereal Campylobacteriosis in the Hay District
Ian Masters, District Veterinarian, HAY
Beef cattle have traditionally played second fiddle to merino sheep in the Hay district and cattle management has been fairly basic. Irrigation developments, improved water supplies and a reduction in rabbit numbers have all contributed in a steady rise in cattle numbers from around 19,000 head in the 1960's to around 93,000 in recent years. There has been a bit more interest in cattle management over the last few years and I have been involved with infertility investigations in herd improvement programmes initiated by Chris Callow, Livestock Officer, Beef Cattle at Yanco. This paper deals with three of the herds we have been working on. Vibriosis was confirmed on two of these properties and suspected as one of the causes of infertility on a third.
HISTORY
The first property investigated is a 10,462 ha holding in the Booligal district. They run 1,100 Hereford breeders and only a handful of sheep. The owner is very keen on beef cattle management and is a member of a small Beef Improvement Group. He was concerned for some years about the high numbers of dry cows and heifers culled each year but was often told that this was what you had to expect, running cattle in this sort of country. In January 1989 he found a number of early term aborted foetuses in a mob of heifers. They were typical hairless, oedematous vibrio type foetuses but most had been attacked by predators and lacked vital organs for lab examination. Histopathology of lung sections from one specimen was suggestive of a bacterial pneumonia. Preputial scrapings of 5 bulls confirmed Vibriosis in one Angus bull. There were some bull management problems in this herd also and fertility has improved with the introduction of a vibrio vaccination programme for bulls and improved bull management.
The second property is located north of One Tree on the Lachlan River. It is around 13,000 ha running 8,000 sheep and 250 - 300 Shorthorn breeders. Roughly half of the property is subject to flooding. Very high fertility is a feature of the sheep flock on this property and in recent years the owner has made an effort to sort out his cattle herd. Infertility had been a problem for some time. Stray bulls from a neighbouring property interfere with normal management. Agistment cattle are taken on in good seasons. The initial investigation showed poor fertility overall but this was most obvious in the heifers and first calvers. Vibriosis was suspected but could not be confirmed from preputial scrapings collected from several bulls.
There were problems with the head bail and bulls could not be properly restrained. It was difficult to collect good scraping for culture. A number of bulls in this herd were replaced due to structural faults, small testicles and old age. A Vibrio vaccination programme for bulls and Lepto. vaccination programme for females was commenced. Fertility in this herd is steadily improving.
The third property joins onto the Southern end of the second property. It is around 12,000 ha and carried 8,000 merino breeders and 300 Shorthorn breeders. About two thirds of this property goes under in a big flood. Fertility in this herd has been substandard for many years. Bull purchases have been from the one source and the owner breeds a lot of his own replacement bulls. He keeps 6 - 8 bull calves each year to join to heifers and retains the best of them as replacement bulls. There is about a 2% incidence of congenital Cerebellar Hypoplasia in this herd. The property is conservatively stocked and agistment cattle are taken on in good years to utilise extra feed. I was asked to do an infertility investigation in this herd at the start of the year. Cattle had been joined for five months from August to the end of December. About 5% of bulls had been used and the cattle were in 3-5 score condition. About 65% of the heifers were pregnant. They had been joined at 14 months of age, were well grown and in good condition. Very few were well in calf. Most were 10 - 12 weeks pregnant. They had been running with two older bulls for the first two months of joining. These were replaced with three young bulls for the last 3 months. Less than 50% of the first calvers were pregnant and around 70% of the cows were in calf.
The herd had been sent on agistment to Victoria and Queensland during the drought in the early 1980's. The owner has also allowed the owners of agistment cattle to use his bulls in recent years. There is some movement of cattle between the last two properties because of the difficulties in maintaining fencing in flood prone country. The history was very suggestive of Vibriosis but there were some obvious management problems as well. There were a lot of late calves in the mob but when cows mothered up many of the empty cows had 5 - 6 month old calves at foot.
Facilities were not adequate to collect preputial scrapings from bulls so vaginal mucous samples were collected from 10 empty heifers and first calvers. Wet smears were negative for Trichomoniasis but Campylobacter fetus venerealis biotype venerealis was cultured from two bulked vaginal mucus samples. Samples were also submitted to Armidale Laboratory for Elisa testing but all 10 samples gave negative results. This may be due to the way the samples were prepared rather than a fault with the test. Most of the culls had been sold before the test results cam back and it was not possible to repeat the test.
CONCLUSIONS
Vibriosis may be widespread in the Hay district based on the results of the limited investigations carried out so far. In my experience I have not had much luck confirming a diagnosis of Venereal disease in cattle with preputial scraping taken from bulls. Vaginal mucous samples collected from recently joined heifers and material collected from aborted foetuses have been more rewarding. As with most diseases the greater range of samples you submit the more likely you are to confirm a diagnosis.
Bull vaccination programmes appear to be giving good results in the herds I have been involved with but this has been carried out in conjunction with improved bull management. Culling older dominant ineffective bulls may be helping to improve fertility. They are probably the main reservoirs of Campylobacter as well.