Bovine respiratory disease in calves
MORTALITIES of two calves reported to me by farmers in Bubi and Bulilima districts inspired this week’s instalment. Both farmers described the deaths of their calves from conditions and symptoms, which are consistent with a respiratory-related disease.
Mr Mantuli from Diba area in Bulilima District indicated that his calf had difficulty breathing, showing signs of congestion within the respiratory path. While this could be a result of a number of diseases I found it imperative to discuss one respiratory disease in calves. This is called the bovine respiratory disease.
Bovine respiratory disease (BRD) or pneumonia is common in commerciallyreared beef calves and yearlings. It causes inflammation of the lung tissue and airways, and damage may be irreversible in severe cases.
The symptoms of BRD are reduced feeding, raised temperature (above 39.4°C), increased breathing rate and effort, head down and looking depressed, coughing, nasal discharge which may become thick and purulent with time due to secondary infection and death.
BRD occurs when the challenge of infection from pathogens overwhelms the immune defences of the animal. Many factors influence this such as:
Colostrum intake at birth is vital. Calf health hinges significantly on the provision of adequate amounts of good-quality colostrum at birth. Passive immunity is passed from mother to calf through her milk, providing the only means of protecting the newly-born calf against disease.
The effectiveness of colostrum is determined by the quality, quantity consumed and how quickly the calf receives it. It is thus important for farmers to observe and ensure that the newly-born calf suckles and gets the colostrum within the first three hours or so.
The ability of the calf to absorb antibodies from the colostrum decreases significantly as the time from birth increases. This is where most communal smallholder farmers face challenges because their animals calve down unsupervised or even unnoticed.
This usually happens in the bush and the farmer either just suspects that it has calved down because it has been missing for a day or two or it pitches up with a calf on foot after a few days missing. Therefore colostrum intake by the calf becomes more assumed than observed. An uncle of mine only realised after three days that his cow had a dead udder and therefore the calf was not receiving any milk. He had just seen the calf following the dam around and assumed all was well!
An observation tool that can enable farmers to be almost sure that even if the calf was born out of sight and they could not see it taking colostrum, farmers can look for the following signs; abdominal distension in the calf, calf active and alert, dam’s udder empty.
Adequate nutritional provision is important for calves. The immune system of malnourished animals is weak. Calves’ defences can be improved by supplying the correct nutrition to meet their requirements at every stage of development.
The impact of the weather also needs to be considered. In cold, wet and windy conditions, energy requirements are higher and therefore energy intake of young stock needs to increase.
Stressing calves can result in poor performance of calves. Calves can fight disease better when they are not stressed and hence it is important to perform management practices at the appropriate time to avoid stressing your calves.
For example it is not advisable to carry out such practices as castration and dehorning at the time of weaning. Weaning is already enough stress on its own without the addition of these other physical factors.
Calves, like any other animal get exposed to disease conditions through a number of paths. This includes mixing calves from different herds and age groups. If there are infected calves the disease is passed to other calves.
Another predisposing factor for disease prevalence is the environment itself, for example damp conditions can favour some pathogens as well as affecting animal behaviour and forage quality, which all contribute to the risk of BRD.
Temperature extremes and variations can contribute to respiratory problems within your calves. Farmers should therefore provide housing which can protect their calves from all the vagaries of unfavourable weather conditions.
In managing the environment of the calves it is essential to ensure that they are not exposed to heavy parasite burdens such as that of flukes and worms. Many respiratory and intestinal pathogens thrive in moist environments and generally find it hard to survive in dry conditions.
Primary aim of healthy animal production is to prevent the accumulation of excess moisture in the housing as this contributes to pathogen build-up. It is my hope that these few tips can help you farmers to deal with your challenges relating not only to BRD but calf health in general. I wish all followers of this column a Merry Christmas and a productive year ahead of us.
Uyabonga umntakaMaKhumalo.
Feedback mazikelana@gmail.com or cell 0772851275.