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This article was published in 1992
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A Bloat Mortality and the Use of Rumensin (Monensin) Anti- Bloat Capsules (Elanco)
Barry Kemp, District Veterinarian, Forbes
The problem occurred on an area of 45 hectares of lush growing lucerne divided into 4 paddocks. There was only 1 paddock of 14 hectares of grass available. The lucerne was not irrigated. The lucerne was 'Aurora' variety.
The owner had 64 yearlings (48 steers and 16 heifers) and 50 cows.
The yearlings were given Monensin Anti-bloat Capsules on 16/6/1991. Animals weighing less than 160 Kg liveweight were not treated. The cows were given the capsules on 17/6/1991. There was no problem experienced in the cows.
There was no withholding period from the lucerne with this first lot of capsules.
Twelve to fourteen capsules had expired prior to the administration on 16/6/1991. They were Mexican capsules and were last manufactured prior to January 1991. Therefore, they were at least 18 months expired on the date of administration. The Australian Capsules were manufactured from January 1990. The remaining capsules were purchased by the owner on 15/6/1991 and would have numbered more than 100.
The breeds of the animals that died were Herefords, Shorthorns, Santa/Hereford cross and Limousin/Hereford cross. The only animals not affected were Hereford/Angus cross steers.
The age of the animals affected was 12 to 14 months.
Total number of animals that died was 12 (10 steers and 2 heifers). The number died that had been given capsules was 9 (8 steers and 1 heifer). The number that died that had not been given capsules was 3 (2 steers and 1 heifer).
The period of deaths was between 14/6/1991 to 9/8/1991.
A second lot of capsules was given to half the yearlings. There is a discrepancy in the dates of administration. The owner's date is 23/7/1991 and he advised he gave them a 4 day withholding period before letting them out onto the lucerne. Elanco's date for the administration of the second lot of capsules is 31/7/1991 (as per diary of Elanco Rep.)
The cattle were vaccinated on 26/2/1991, with 5-in-1 vaccine (some of which had been expired for 12 months). They were again vaccinated at the end of March 1991 (P.K. - Tetanus vaccine) and again on the 4/7/1991, with 5-in-1. The writer advised another 5-in-1 vaccination at the end of July.
Mortalities
The first animals to die were two steers which died on 14-15/6/1991. This was before the first lot of capsules was given.
The next animal affected died on 28/6/1991 and was post-mortemed by the practitioner. It was a steer and had been given a Bloat Capsule. It was in good condition. Enterotoxaemia was suspected but the cause was not determined from examination of specimens at the Laboratory. (ON91/1143)
Two more animals were found dead on 3/7/1991 (1 steer and 1 heifer) and were post-mortemed by the practitioner. He commented that the post-mortem did not suggest bloat. He again suspected Enterotoxaemia as did the Laboratory report (ON91/1165).
The District Veterinarian's first visit was on 5/7/1991, at 5.00 PM. It was a heifer with the legs in the air. The carcase was not fresh. Kidneys were very pulpy. Liver was pale and at least 2 large abscesses were present (approximately 2 inches in diameter) spleen normal. Small intestine not reddened. Bloat capsule present. (Animal found dead in the morning).
District Veterinarian's second visit was on 12/7/1991, to inspect cattle coming out of the lucerne at 4.00 PM. No animal was seen excessively bloated.
One steer died on 10/7/1991. A capsule was removed from this animal on 12/7/91.
A smaller steer died 3 weeks previously and was opened up on 12/7/91, but no capsule was present (being too small on the date of administration of the capsules).
Another visit was made by the District Veterinarian on 18/7/91 and a steer was post-mortemed - which showed considerable post-mortem decomposition. Laboratory report ON91/1305. Kidneys soft. Only small amount of small intestine showed changes - red from outside and white exudate inside (6-8 cm in length). Muscles in shoulder area - darkened in colour and subcutaneous reddening. Bloat capsule removed. Laboratory diagnosis: cause not determined.
Post-mortem on 21/7/91 - steer. Laboratory report ON91/1306. Animal died at 4.40 PM and post-mortemed at 6.40 PM - fresh carcase! Bloat capsule removed.
Carcase very bloated, eyes prominent, conjunctivae congested, tongue well protruded, haematomas in frontal sinuses, subcutaneous congestion in anterior part of body around shoulders, emphysema of inside thigh area where hind legs join abdomen, congestion of trachea at bifurcation, anterior lungs congested, small amount of straw coloured fluid in pericardial sac, a few petechial haemorrhages on epicardium, liver fairly pale, kidneys not soft, small part of terminal ileum had a small amount of white contents and congested; quite extensive length of middle small intestine had white creamy contents and shoulder muscle was darker in appearance. Laboratory diagnosis: Bovine mortality - suspected bloat. Laboratory comment: Histopathology non-specific but the post-mortem findings and lack of any specific diagnosis form Laboratory tests would suggest bloat.
Post-Mortem on 4/8/91 (Sunday) - Steer - carcase blown up and gone off considerably. Blood coming from rectum. Spleen normal size, liver pale, subcutaneous congestion - particularly anterior part of beast, 2 anti-bloat capsules in rumen (1 Australian and 1 Mexican). Small amount of variegated thistle growing in lucerne, low to the ground. Laboratory report ON91/1434. Laboratory diagnosis: Negative for Anthrax.
Visit on 6/8/91. - Laboratory report ON 91/1444. - Variegated thistle tested for nitrate - Laboratory report ON91/1444. Laboratory result: positive for nitrate. Also inspected hay being given to cattle - contains approximately 80% lucerne, also contains Paterson's Curse, rye grass, black oats and a little wild phalaris. Hay cut on owners property and was made October - November, 1990. One bale was given/day to 16 heifers, 6 bales were given/day to 43 steers.
On 9/8/91, one steer (Hereford) 14 months of age was taken to R.V.L., Orange by the owner. 2 anti-bloat capsules were recovered (one Australian and one Mexican). Laboratory report ON91/1462. Laboratory diagnosis: Mortality due to Bloat. Laboratory Comment: The autopsy findings along with negative results from the other Laboratory tests support a diagnosis of bloat.
Elanco Laboratory findings on Anti-bloat Capsules
| Capsule Batch No. | Country of Manufacture | Date of Death | Initial Core Length (mm) | Final Core Length (mm) | Days in Animal | Payout mm/day | Comments |
|---|---|---|---|---|---|---|---|
| EL085520 WAB | Mexican | 8/7/91 Elanco date 5/7/91 D.V.'s date |
133 | 98 | 22 | 0.7 normal Elanco (or 0.6mm for 25 days D.V.) |
Expired prior to administration |
| EL08572 WAB | Mexican | 10/7/91 | 113 | 105 | 24 | 0.3 Abnormal | Expired prior to administration Goodwill payment |
| EL0171 AL | Australian | 3/7/91 | 110 | 98 | 17 | 0.7 Normal | |
| ELO8572 WAB | Mexican | 17/7/91 | 113 | 96.5 | 31 | 0.5 Abnormal | Expired prior to administration Goodwill payment |
| ELO8552 WAC | Mexican | 21/7/91 | 113 | 81.4 | 35 | 0.9 Normal | Expired prior to administration |
| Animals dying of Bloat after second capsule administered. | |||||||
| ELO8572 | Mexican | 3/8/91 | 113 | 76.3 | 49 | 0.75 | Expired prior to administration |
| ELO836 AL | Australian | 110 | 104.4 | 3 | 1.9 Normal for the first week | ||
| ELO572 | Mexican | 9/8/91 | 113 | 100.1 | 55 | 0.2 Abnormal | Expired prior to administration |
| ELO836 | Australian | 110 | 93.21 | 9 | 1.86 Normal for the first week | ||
Differences in owner's use of capsules and Elanco's recommendations
1. Minimum liveweight to treat.
a. Elanco: Do not dose animals less than 200 Kg liveweight.
b. No animals treated less than 160 Kg liveweight by owner.
2. Withholding period before putting onto pasture.
a. Elanco: Wait 7 days before placing dosed animals on bloaty pastures.
b) Owner: First dosage of capsules - no withholding period. Second dosage of capsules - animals withheld 4 days.
The reason was lack of alternative pastures which were not lucerne.
3. Expiry: Four animals died with a single capsule which had expired prior to administration.
One animal died with a new capsule.
Two animals died with one new and one expired capsule.
(2 capsules thrown away and not examined).
Another Elanco recommendation.
Do not retreat animals for at least 100 days. Owner reported no ill effects in animals doubled dosed (other then the deaths of 2 animals). The Elanco Rep. at Forbes now recommends 2 capsules can be given at a 95 day interval between each capsule.
After the last death on 9/8/91, the owner put out two water troughs with a Bloat oil added. It took 3 days for the cattle to take to it and he experienced no more deaths after that.
During the time of the problem with mortalities, the cattle had access to the lucerne and the gate was open with access to the river for water where there was a grass paddock with not much grass, except for 3 weeks prior to the second capsule when cattle were taken out at 3:30 PM and put back the next morning between 7:30 and 9:00 AM, except for 3 days when cattle were taken out at 4:30 PM and after 5:00 PM and 6:00 PM and on each occasion one was dead the next morning. The owner lived away from the farm.
After the loss of the two heifers, the heifers were put into a grass paddock and they did not go back to the lucerne.
The year before, in 1990, the owner used all Mexican capsules. Eighty to ninety capsules were used on steers and heifers, 12 months of age. The owner reported similar seasonal conditions (very wet). He lost one animal before the capsules were given and then none after the capsules were administered.
Some lucerne was sown in May, 1989, some was sown in 1990 and some was sown in 1991.
Elanco claims that Rumensin anti-bloat capsules reduce bloat deaths by at least 80%.
Elanco veterinarian advised on 7/2/1992, that there has been an ongoing process of evolution and development of the Rumensin Anti-Bloat Capsules since the Mexican model. The cap, previously spin welded to the body, is now secured with a stronger 'clip-lock' mechanism. The core has been shortened, the 'wings' strengthened, individual numbering of the capsules introduced and development of the plunger and spring.
ACKNOWLEDGEMENTS
To Elanco Veterinarian, Dr Lisa Wade, BVSC, MRCVS, for results of the examination of the Rumensin Anti-Bloat Capsules and for technical information on Rumensin and on the Anti- Bloat Capsule.
2. To Mr Mike Kupkee, of Elanco Animal Health for his information.
3. To the owner, for his information on the history.
4. Mr Peter Moate for information on the Proceedings on Bloat of 5 & 6/8/1991 at the D.R.D.C. Bloat Workshop at Dairy Research Institute, Ellinbank, Warragul, Victoria, 3820.
REFERENCES
1. Elanco Booklet 'Bloat Control and increased production. The latest technology' - 2nd edition, April 1991
2. Rumensin Technical Manual
3. Rumensin Anti-Bloat Capsule Technical Information. - GJ Ball, July 1990
4. 'Bloat' - D.R.D.C. Bloat Workshop Proceeding, D.R.I., Ellinbank, August, 5 & 6, [August] 1991