4 April 2008

5 minute read

The health management of the cow and the early immune development of the calf provide the best opportunity for improving BRD inefficiency.

"How calves are managed prior to shipment from the ranch, by improved animal husbandry and utilization of available technology, provides the most immediate avenue to improved efficiency," Dr Rogers said in a presentation to the US National Cattlemen's Beef Association Convention in Reno, Nevada recently.

He said that before a BRD control strategy can be put in place, the producer has to address the general operational goals and objectives. To construct an effective strategy it is also necessary to understand where the animal is likely to be sent post-weaning - such as an auction mart, feed lot or wheat pasture.

Control measures need to ensure that there is early planning to make sure the farm or ranch is complying with any selected Value Added Calf programme that might be adopted. Correct and adequate records need to be kept and programmes to ensure that health products are administered at the correct time need to be in place as well as conducting diagnostic tests for BRD.

"Ultimately, the goals an objectives of ranch BRD control should prevent BRD while on the ranch, meet selected marketing programme goals and provide the buyer/end-user with minimal BRD problems," Dr Rogers said.

He said that a BRD programme should be considered part of a marketing plan to ensure that there are no financial disasters.

Dr Rogers said that while the calf might be the central focus of any BRD control programme, one of the most important aspects is the health management of the cow herd of origin.

Maternal health and immune status is crucial for longer-term calf health performance.

Dr Rogers stressed that there are in-borne difficulties in maintaining and complying with health programmes for calves - particularly when they are moved from one facility to another - and there are more difficulties in maintaining records for cow herd health programmes. However, the importance and application of the information in these records is significant.

Colostrum

He said that in one piece of research looking at the impact of colostrum management demonstrated the need to look not just at the calf health programme but also the cow.

One study with beef calves showed that those experiencing inadequate immune transfer from colostrums were three times more likely to die.

Another study of dairy heifers fed two different amounts of colostrum within the first hours of birth showed that those fed the lower amount had double the veterinary costs. The heifers fed the higher amount showed greater weight gain and eventually higher milk yields.

"The direct economic return to the producer was approximately $160 per cow in additional milk produced over two lactations," said Dr Rogers.

"From a practical beef cow/calf perspective, the most important method to increase colostral immunity is to understand the risk factors associated with inadequate passive transfer and modify the factors that can reasonably be corrected."

This all includes managing dystocia (calving difficulty), culling cows with bad udders, maintaining adequate body condition at calving, providing adequate trace mineral nutrition and sound cowherd immunisation.

Foetal Programming

Dr Rogers said that while foetal programming is limited in livestock, some studies have shown that it can be of help with maternal nutritional and health management and foetal development and also in the long term total performance.

One study in Nebraska had shown that supplementing cows with protein during late gestation, while not affecting the birth weight of calves, did have an impact on heifer calf weight and reproductive performance. Heifers from protein supplemented calves tended to have higher pregnancy rates (94 per cent compared to 73 per cent). They also calved earlier and had a higher number of unassisted births (69 per cent compared to 38 per cent).

BVD Control

One major area of control to reduce Bovine Respiratory Disease Complex is control of the respiratory virus that causes immunosuppression leading to BRD.

There are both technological and management tools available to eradicate the virus - BVD - on individual farms and prevent it from moving to other farms.

Control of the virus needs effective immunisation before breeding and identifying and removing persistently infected cattle.

Dr Rogers said that a vaccination programme should be standard practice and whole herd testing to identify BVD-PI needs to be based on risk analysis and health monitoring. In cases where there is good record keeping and good practices and good reproductive performance, whole herd testing might not be necessary or economically beneficial.

Early vaccination - between one and four months - helps to improve immunity and prepares the calf for a more robust immune response later. Dr Rogers said that recent research shows that early modified live vaccination (IBR and BRSV) stimulates a cell mediated (CMI) response and memory helping a stronger response in later vaccination.

"Modified Live Vaccines (MLV) are more likely to exert this positive effect and override maternal antibody blockage," said Dr Rogers.

The best time to immunise is before the animals can be exposed to the disease and this is calculated at between three to six weeks, prior to weaning.

"This practice allows calves the opportunity to respond to immunisation in a low stress environment, accompanied by maternal presence and a high quality nutrient source (milk) supplied by the dam," said Dr Rogers.

He said that properly weaned and immunised calves perform better than freshly weaned calves.

Another BRD control strategy that needs to be considered is early castration as studies have shown that steers arriving at a feedlot are less likely to have respiratory problems that bull calves castrated on arrival.

Dr Rogers said that although there are numerous novel and highly effective technologies to deal with BRD, the condition still plagues the industry and an effective control programme is an essential strategy for producers.