Extreme conditions in South Africa results in temperatures from as low as -10 °C in winter to over 40 °C in summer. Different breeds will adapt differently to this, but a typically feedlot situation may have a wide variety of breeds which puts more challenges on management. Heat stress, an underestimated issue in beef cattle, remains the biggest obstacle in a feedlot situation. In dairy cows, the impact of heat stress can be easily measured. Lower milk production, less feed intake and many more variations from cows’ typical behaviours can be seen. However, in beef cattle, the signs of heat stress are much less visible. Although there is less visibility, fattening cattle suffer just as much as dairy cows in warm temperatures. Heat stress has a direct impact on the time that the rumen functions under low pH conditions which results in:
- A decreased feed Intake, leading to negative growth rate, which can even lead to muscle loss due to low ingestion
- The quality of the meat may also deteriorate (higher pH at the slaughterhouse, which can impair meat ripening).
- Ultimately, if the animal fails to cool down, this may lead to sudden death (e.g. enterotoxemia and heart failure)
To be more efficient, we are constantly pushing the boundaries of higher starch inclusions in feedlot rations. This is creating new challenges of which the biggest is to maintain a healthy rumen environment. Rumen acidosis or sub-acute rumen acidosis (SARA) is a big challenge in all feedlots and can lead to huge losses in production and even death. In most cases animals are taken out of their normal extensive environment and put into a high production and high-density environment. This leads to higher stress levels and will have a negative impact on feed intake, nutrient absorption and growth rate.
It’s crucial to maintain optimum feed intake under feedlot conditions while maintaining good rumen health to ensure optimum production.
Rumen health is directly linked to several other health problems found in ruminants. Rumen acidosis can be the cause of several health issues in ruminants. These includes:
- poor immune function
- liver abscesses
- high un-explained death loss (or cull rates)
Maintaining a good health status and reducing veterinary cost play a major role in sustainable profitability.
Mycotoxins are toxic chemical molecules produced by fungi. They are found in all grains, oilseeds, roughages and silage. Acute mycotoxicosis is the result of high contamination and clinical signs such as low feed intake, vomiting, dermal lesions, liver and kidney damage and mortality is visible. In most cases subacute mycotoxicosis occurs where no clinical signs are visible. This leads to poor performance of the animal due to depressed immunity, digestive troubles and poor nutrient absorption which leads to poor FCR. Subintoxication or chronic intoxications are now widely considered to be the most important impact of mycotoxins.