May is a busy time of year for all of the agriculture sector. For farmers, spraying and seeding is in full swing. For ranchers, May can involve calving, health management, moving pairs to pasture, branding, etc. It is important to understand calf management to meet production targets. Production targets include a 63 d calving season, having over 95% of the cow crop calving and less than 4% of calves dying between birth and weaning.
Understanding the causes and timing of calf mortality is key to decreasing death loss and
increasing profitability. The image to the left illustrates the average percentage of dead calves based on timing. It is important to learn all the risk factors so management strategies can be implemented and interference can occur in a timely manner. Dystocia or calving complications is one of the leading causes of neonatal death.
The image below shows the most common causes of calf loss at under three weeks of age vs. over three weeks of age. The most common causes of calf mortality are dystocia, environmental conditions, passive immunity, infectious disease, calf vigour, maternal nutrition, and maternal behaviour.
Colostrum is the very first and most important step following parturition. Calves are born with basically no immune system and need the immunoglobulins from the colostrum to begin the immune system development. The rumen wall allows the passive transfer of the immunoglobulins into the blood stream of the calf. However, the porousness of the rumen wall begins shifted almost immediately after birth. Therefore, the calf needs colostrum within the first 6 hours after parturition for adequate passive transfer. After 24 hours, the rumen wall has shifted composition and there is relatively no transfer of maternal immunity. If the cow is unable to provide colostrum for the calf, for whatever reason, it is important to supplement colostrum using powder or frozen colostrum. This early intake of colostrum also provides the calf with energy, nutrients, warms the calf, and hormones.
Scours (or diarrhea) in calves will cause dehydration and death in calves. Scours can be caused by bacteria, viruses, protozoa, and nutrition. Nutritional scours is uncommon but can occur from over-consumption of milk. Some vaccines are available for gestating cows that will transfer antibodies to the calf to prevent neonatal scours. The diarrhea can be bloody depending on the cause of the scours and will cause the calf to become dehydrated very quickly. It is important to respond quickly to scours cases with antibiotics, electrolytes, and sulphur boluses when necessary. Rapid observation and response can decrease the risk of calf mortality caused by scours.
Management practices for older calves is very dependent on weather, nutrition, and stress levels. Stress levels can be caused by moving pairs to new pasture, water shortage or having to fight to get to a trough, and events such as brandings. Creep feeding is an option for adjusting calves to forage diets. Creep is often used when pasture quality is poor, pasture quantity is limited, poor cow condition. Grain prices need to be low enough to make creep feeding pencil. This years grain prices will increase the price of creep feed and therefore, may not be the solution to the low quality and quantity of grass this year. Creep feeding has been shown to increase weaning weight, feed intake at weaning, and cow condition, weight, and conception rate while decreasing grazing pressure. However, creep can be costly and intake is inconsistent. This can mask the cow's mothering ability and performance, as the calf may be eating more creep and therefore, the grains are often fat not muscle. Some markets will discount these animals as they are over-conditioned for some feedlot settings.
Calf health and survival is the most important aspect of a cow-calf operation. It is important to understand all the risks and how to respond to them. Hopefully this will direct your attention to what has been causing mortality on your ranch. Let me know if you have any questions or would like to discuss any prevention or treatment practices.