The Sunday News
Mhlupheki Dube
ONE of the stressing situations to any livestock farmer is the mortality of young ones. This could be calves in cattle, kids in goats, lambs in sheep and chicks in chickens. I have often received distress calls from a number of cattle farmers following a calf mortality situation or a sick calf.
In calf management, mortality is classified into two broad categories namely perinatal mortality, which typically refers to mortality of full-term calves during parturition and up to 48 hours after birth, and postnatal mortality, which refers to mortality after the perinatal period, up to a designated time point, such as weaning.
I have come across farmers complaining that they tend to lose their calves around five months of age and they are baffled as to the causes.
Such postnatal mortality can be due to a number of factors and I will examine one major factor which causes calf mortality.
This is called the weak calf syndrome. Weak calf syndrome presents as a newborn calf that is weak, unable or slow to rise, stand or nurse.
This is not a very common syndrome but occasionally it occurs in beef herds and with resultant perinatal mortalities.
The weak calf syndrome is caused by a number of factors such as bad weather (cold and/or wet) resulting in hypothermia (low body temperature), poor nutrition for cows in late gestation, calf involved in a dystocia; White Muscle Disease (Selenium deficiency); Leptospirosis; Trauma to the calf (being stepped on or laid upon), age of the cow — higher incidence in calves born to heifers and very old cows.
Severe weather conditions such as cold and/or wet cause stress on pregnant cows soon to calve. This added stress can directly reduce cow immunity.
Also low feed intake during severe weather can further decrease immunity and result in weight loss.
Under these conditions parasite load can increase, further compromising the cow.
Combining these factors can result in the cow taking a longer time to push the calf out during delivery, resulting in a weaker calf at birth.
With regards to cow nutrition, weak calf syndrome has been associated with low energy and protein nutrition in late pregnant cows. Therefore, during the last two months of gestation cows should receive adequate protein to reduce the incidence of weak calves.
Energy in the diet of cows has also been seen to be important because calves born to thin cows are at increased risk of weak calf syndrome.
Dystocia also results in weak calf syndrome because a calf involved in a difficult birth undergoes more stress but also can become hypoxic (low oxygen levels) which can result in neonatal acidosis.
Acidosis results in a weak calf and if not corrected, can result in death. Calves involved in prolonged dystocia may die soon after birth. If they do happen to suckle, they don’t absorb maternal antibodies from colostrum as well, making them more susceptible to scours and pneumonia later in life.
White muscle disease is caused by selenium deficiency due to deficient soils in which forages grow.
If pregnant cows are deficient, calves may be born with a weak heart or muscles and die soon after birth.
It is therefore important for farmers who know that their area is deficient in such important minerals to provide supplements and prevent such occurrences.
Leptospirosis causing bacteria have been found in a number of calves with weak calf syndrome, however, no clear correlation has been established.
This is a subject for further study by researchers but it is important to note that diseases such as leptospirosis can cause abortions in cows due to the high fever they cause to the cow.
Another factor which has been seen to be linked to the weak calf syndrome is the age of the cow.
First-calf heifers and very old cows are more likely to have weak calves. For both age groups, nutrition is likely to be the underlying reason. Heifers are still growing when they are pregnant and if deficient in protein and energy, may give birth to a weak calf. Heifers are also more likely to have a difficult calving because they are first timers. Older cows may have difficulty in foraging and maintaining a good body condition score. After all has been said and done, it can be concluded that good management can help prevent or reduce incidences of weak calf syndrome in your herd.
Uyabonga umntakaMaKhumalo.
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