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|Large-herd Vermont dairy trials new three-way intranasal respiratory vaccine|
|Dairy basics - New Technology|
|Written by PD Editor Walt Cooley|
Respiratory problems are the second-most significant disease for youngstock on dairy operations, behind scours band diarrhea, according to the 2007 National Animal Health Monitoring System (NAHMS) survey. The same study found respiratory disease is the single-largest cause of death among U.S. weaned heifers, with 46 percent of all weaned heifer deaths attributed to this cause.
Richard Nelson of Nelson Farm Inc. in Vermont identifies the threat of respiratory disease as his primary concern for raising replacements.
“The only thing I’m really worried about losing a calf to after they are more than 10 days old is a respiratory challenge,” Nelson says.
Earlier this summer, Pfizer Animal Health approached Nelson to on-farm trial its new three-way intranasal respiratory vaccine, now known as INFORCE 3, prior to its commercial release earlier this fall. The new vaccine is labeled to prevent disease caused by bovine respiratory syncytial virus (BRSV) and aid in prevention of respiratory disease caused by infectious bovine rhinotracheitis (IBR) and bovine parainfluenza3 virus (PI3). More than 60 percent of all U.S. operations vaccinate heifers for these three respiratory diseases and more than 75 percent of all large-herd dairies vaccinate for them, according to the 2007 NAHMS report.
Prior to the trial, Nelson’s calf operation had been using a TSV-2 vaccine administered intranasally at two to seven days of age and again at weaning (two months old), followed by a BRSV vaccine and booster administered three months later in order to vaccinate against respiratory challenges. He says he has also used a previously commercial-available five-way modified-live respiratory vaccine that was delivered intranasally.
“Before the trial I thought intranasal vaccines were necessary for raising healthy calves on our operation. Now, afterwards, I know intranasal vaccines are necessary for raising really nice, thrifty calves,” Nelson says.
About a year ago, Nelson built a new calf nursery to replace individual calf hutches and house, under one roof, his near-constant herd of 200 wet calves from his 2,500 cows milked on four different dairies in northeast Vermont. The new calf facility is an insulated 52-foot by 200-foot barn with natural ventilation and curtain sidewalls. Calves are housed in individual, wire-mesh pens. The furthest dairy is 50 miles away from the new facility and calves are transported several times per week.
“Our loss rates were better in the new facility but not where we wanted them to be,” Nelson says. “In March, we added a milk pasteurizer, and our losses due to scours fell to way less than 1 percent.”
However, prior to the start of the trial in mid-July, Nelson reports his mortality rate due to respiratory disease was 5 percent and his respiratory challenge incidence rate was 15 percent.
“This was unacceptable to us,” Nelson says.
During the trial, and since continuing to use the product after its release, Nelson says his rate of respiratory incidence has dropped to less than 5 percent as has his death loss, which has dropped to near zero.
“They got INFORCE 3 to us and I started using it on my baby calves. I lost exactly one calf to respiratory disease out of 250 doses given. And in my mind I didn’t get it into that calf early enough,” Nelson says. “I was very, very impressed.”
Nelson admits that the trial did not occur during the times of the year he sees the most respiratory challenges, during spring and fall when temperatures are variable. But since he’s continued using the new intranasal respiratory vaccine in his protocol he says mortalities due to respiratory diseases have “basically stopped.”
“It’s not that we don’t treat some calves for respiratory disease, but we have excellent results now when we do treat them,” Nelson says.
Dr. Gregory Edwards, a Pfizer Animal Health Technical Service veterinarian, says the vaccine was developed specifically for intranasal use and should not be compared to previously available, intranasally administered respiratory vaccines.
“This vaccine reacts very quickly,” Edwards says.
Edwards says that producers and veterinarians will recognize the vaccine’s quick reaction time, similar to the TSV-2 intranasal vaccine, due to the vaccine’s ability to stimulate interferon release. However, the vaccine’s antigens stimulate a different portion of the immune system than other previous respiratory vaccines.
“This vaccine stimulates a different portion of the immune system than injectable vaccines,” Edwards says. “It stimulates high levels of IgA, which is a different immunoglobulin or protective portion of the immune system, than injectables do. The injectables stimulate IgG, which is similar to protection you get from colostrum.”
Understanding the difference between IgA’s and IgG’s is important to understanding the uniqueness of this vaccine. Colostrum from a dam who has been vaccinated against respiratory diseases or has immunity experience with them will contain IgG’s or passive immunoglobulin protection. Edwards says that this type of protection recedes over time. This leaves the calf or heifer exposed at some time early in life to respiratory disease challenges. However, it is this same maternal protection that also inhibits injectable vaccines from building antibodies or immunity against disease early in a calf’s life as the IgG’s in colostrum override the efficacy of IgG’s resulting from an injectable vaccine.
“With this intranasal route and our bovine respiratory syncytial virus (BRSV) antigen, we have been able to show we are actively immunizing a calf against disease and still carry the maternal antibody,” Edwards says.
This active immunity is what helps protect youngstock early in life until passive maternal antibodies have worn off and an injectable form of BRSV will again be efficacious in vaccinating against disease later in life.
As part of the Nelson’s on-farm trial, he gave the new three-way intranasal vaccine to 30 calves at weaning that had received TSV-2 shortly after birth. Nelson says observing their reaction keyed him into what he thinks is one of the major benefits of the new vaccine.
“Those calves never looked back,” Nelson says. “They far outgained the other calves we had in that pen that did not receive the intranasal vaccine.”
Nelson says he hasn’t yet measured his rate of gain for baby calves vaccinated with the new three-way intranasal vaccine, but he would like to.
“I can’t believe how much and how fast those calves are gaining because they never really get that respiratory challenge,” Nelson says.
Due to the increased rate of gain, Nelson believes he will be able to wean calves a week earlier. His metric for weaning age is when a calf consumes three pounds of starter grain per day. The calves vaccinated intranasally with the new three-way respiratory vaccine are getting there sooner, he says.
Nelson says he is curious to see how the new vaccine might be used besides administering it to calves four to seven days old. The vaccine is labeled for safe use in all ages of cattle.
“We don’t want producers to think of this vaccine as having a ‘duration of immunity,’ per se, although there is a period of time its effectiveness lasts,” Edwards says. “We want producers to stimulate the immune system with this early and then we want them to come back at the appropriate time and vaccinate with the injectable form and that will become the booster dose, creating the longer term ‘duration of immunity.’”
Nelson is experimenting with the timing of a second dose of the three-way intranasal product. He believes another dose sometime around weaning may be economical. If he can get the timing right, he believes he may be able to forego the earliest of his four intramuscularly administered BRSV vaccines for young heifers. Even though the new vaccine adds 90 cents more to the cost of his vaccination protocol, he says the potential cost savings from skipping that one intramuscular vaccine (.35 cents) and the increased rate of gain and decrease rate of mortality makes it worth it.
“It’s a win-win,” Nelson says. “It’s paid-back one hundredfold.”
Nelson is also considering using the vaccine with a group of pre-fresh cows this fall and comparing them to another group of cows to see if it may help subclinical respiratory challenges.
“I hardly see respiratory challenges in cows unless they had a previous challenge and are susceptible to it during a stressful period like calving,” Nelson says.
Edwards says producers will find improved safety for the use of the vaccine in adult and high-risk cattle than they may have previously experienced with other vaccines.
“We have taken away the previously-held safety concerns,” Edwards says. “The research has shown this vaccine to be efficacious in use for high-stress, high-risk cattle situations.”
Nelson admits it will be harder to judge the three-way intranasal vaccine’s economical effectiveness in adult cattle since average daily rate of gain as a metric for success in youngstock is much easier to measure than health improvements in adult cattle.
Edwards hopes one benefit of the vaccine will be diminished use of antibiotics to treat bacterial respiratory infections, which he says are often secondary, clinical symptoms for a calf with a viral respiratory infection. And, Edwards says, there may be other possible yet-to-be-explored applications of this delivery mechanism for vaccination.
“If this vaccine is successful, and we think it will be, then we think there are some other respiratory pathogens that may be adapted to this intranasal mode of administration,” Edwards says. “The intranasal technology stimulates a different part of the immune system than injectables do. Depending on what a disease is and when it is occurring in the animal, we may be able to do some things we’ve never been able to do due to this route of administration and the portion of the immune system we are stimulating.”
Nelson claims he already sees the benefits. When added to a good colostrum feeding program and clean, dry calf-raising facilities, the new vaccine will make a significant difference in calf health and growth, he says.
“Give it to them as soon as you can, then stand back and watch them grow,” Nelson says. “The only calf I wouldn’t use it on is a dead one.” PD
Would you benefit from using a three-way intranasal vaccine? The following checklist can be used to determine if this new technology might be a fit for your operation. 1. Do you want to decrease your mortality rate from BRSV, IBR or PI3 diseases?
2. Do your calves experience respiratory incidents and challenges from BRSV, IBR and PI3?
3. Are you satisfied with the efficacy and safety of intranasal vaccines?
4. Do you want to vaccinate cattle of any age against respiratory challenges?
5. Do you already have a solid colostrum-feeding program and clean, dry bedding for calves?
6. Do you consistently measure daily rate of gains for calves and heifers?
7. Do you understand the differences in immune function between IgG’s and IgA’s?
8. Would you like your vaccine protection for BRSV to be labeled for prevention of the disease?
9. Would you like to decrease the use of antibiotics to treat bacterial infections associated with a viral respiratory infection? If you answered yes to six or more of these questions, this technology may be one for you to consider.