Article by Dr Enoch Bergman, Swans Veterinary Services
Did you know ASHEEP & BEEF is running three cattle-oriented Meat & Livestock Australia Producer Demonstration Sites (PDS) simultaneously? We must be crazy! Two of them are firing up for 2024 soon, so reach out to ASHEEP & BEEF Executive Officer Sarah Brown or to Swans Veterinary Services to get involved.
Bovine Viral Diarrhea Virus (Bovine Pestivirus or BVDV)
The first PDS involves measuring the immune status to Bovine Viral Diarrhea Virus (Bovine Pestivirus or BVDV) among groups of heifers prior to mating. BVDV is a serious production limiting disease capable of causing significant reproductive losses or the worsening of other diseases due to its potent ability to suppress an animal’s immune system.
BVDV is spread almost exclusively by Persistently Infected (PI) animals, which were in turn produced from having been exposed in utero to the virus. An animal whose mother is a PI or whose mother is exposed to BVDV (by contact with a PI) between one to four months of gestation will usually be born a PI. They then go forth and complete the cycle again.
Some groups of heifers contain a PI animal. That PI animal will eventually likely waste away and die, but in the meantime, she will transmit BVDV to every cow, calf, or bull she ever meets. Because of this, her own sisters are probably already immune by the time of joining. However, she and her calf are a threat to the next calf crop and to any other management group they should meet, especially if that management group does not have pre-existing immunity itself. This is where utilising heifer pre-mating serology to manage BVDV comes in… which is the thrust of the PDS.
By blood testing a small proportion of your heifers two to three months prior to joining, you can quickly work out if they have immunity to BVDV. If the heifers sampled are mostly immune, one or more of the heifers in the mob could be a PI. If none of the heifers sampled have immunity, then no PI exists within the group. With this knowledge, you can invest in the best intervention - ear notch all of them if they are immune, vaccinate all of them if they are not!
Of the 30 local properties screened last year in the Esperance area, only four had evidence of significant exposure (indicating the possible presence of a PI heifer). Three of the four farms ear notched all their heifers, and two out of three found a PI and were able to cull her before she could cause more trouble.
Of the farms which had evidence of very little immunity, half of the producers decided to protect their heifers by vaccinating them with Pestigard prior to mating, they could then receive an annual booster.
Want to know your heifer’s BVDV status? Get on board! Ring up the surgery and book yourself in on a blood testing road show. The cost of the testing is free and some of the travel is subsidised.
Reducing balanoposthitis in virgin bulls
The second PDS also starts soon and involves attempting to reduce the incidence of balanoposthitis in virgin bulls. By either vaccinating twice with Bovilis MH + IBR, once with Rhinogard intranasally, or both vaccines, we believe we can reduce the incidence and severity of this crippling syndrome which seems to prey primarily on virgin bulls.
Within the district last year, we suffered a lot of balanoposthitis. Even some of our clients whose bulls were vaccinated still suffered significant amounts of breakdown. In the end, the incidence of breakdown was less amongst vaccinated bulls overall, but we still feel like we could do better. We have been discussing using both vaccines concurrently, and also of potentially exposing new bulls to cull cows prior to the breeding season. Obviously, exposing new bulls to old cows carries risk, not only of STD’s but also of bulls injuring themselves or others.
We will keep working in this space, but what was apparent is that producers that vaccinate perceive that it helps, with survey participants giving an average score of 9.5 out of 10 when asked if they believe vaccination helps in the prevention of bull preputial breakdown. The project has provided some free vaccine which we will try to source again, but also it covers most of the costs of investigating bulls that do break down. Again, please contact Sarah or Swans for more information.
Impact of weaning calves earlier
The last project involves measuring the differences between calves and their dams when a proportion of the calves were weaned two months earlier than their siblings. The intention was to improve the weight and condition of the dam without significantly impacting the calf’s weight.
What we found is that even though some properties showed little or acceptable reductions in the weights of the early weaned calves, some showed significant reductions in weight affecting their profitability. Growing calves require 16% to 17% protein to keep moving forward and with this year’s early finish and without milk, many of the calves on some properties were disadvantaged. Their dams, on the other hand, noticeably outperformed the mothers of the unweaned calves both in body condition and weight on all properties. In this way, the project has been at least partially successful, demonstrating the advantage to the dam of weaning early, potentially creating opportunities to increase overall stocking densities or as a drought mitigation tool.
We are hoping to follow along some of the calves which have been retained on properties that grass finish, or by following up on the replacement heifers at other properties. We hope to find that the disadvantaged calves catch up! We really appreciate the producers who took part in this project, especially those who sold their calves shortly after weaning and were the most affected. Some of the producers have agreed to try again – if you are interested in giving it a try, reach out to Enoch at Swans.
Thanks again for all of your support in helping ASHEEP & BEEF to continue running these investigations!
Project facilitator: Enoch Bergman, Swans Veterinary Services
Lead producers: Simon Fowler (Bull Breakdown), Nick Ruddenklau (Weaning), Todd Quinlivan (BVDV).
Contact:
Swans Veterinary Services (08) 9071 5777
Sarah Brown, ASHEEP & BEEF, 0409 335 194