Every year, I receive a couple of calls from beef producers experiencing a bout of acidosis. Unfortunately, by the time they are reaching out to me, they have already had death losses. Often, these producers want to analyze their feed ingredients and pinpoint the issue on a specific ingredient. However, this is not usually the fault of a "bad batch" of feed. Generally, producers want to blame the grain in their diet, but it is not the grain itself that causes this issue. There are other factors that could cause acidosis issues, including switching to a high-concentrate diet too quickly, a weather event that disrupted feed behavior, lack of fiber in the ration and the variability of the grain in the diet from load to load.
Commonly, when producers are looking to blame the feed, they recently got a new load of concentrate feed or switched suppliers. However, they usually did not analyze the previous ingredient or the new load to make ration adjustments. Without a previous report to compare, it is difficult to pinpoint a specific feed ingredient as the cause of acidosis.
In these extreme cases, I recommend first testing the feed ingredients. Then, formulating a step-up plan to get the cattle back to the high concentrate ration they were on before the acidosis issues began. Typically, the producer does follow that advice with the guidance of a nutritionist. However, they then return to business as usual, not analyzing feed ingredients and adjusting the ration accordingly. I would argue that precise feed management could have the benefits of preventing another incident of acute acidosis as well as possibly improving performance.
Furthermore, there is a growing body of literature linking inflammation response to feed efficiency and characteristics involved – such as average daily gain (ADG) and intake. This theme has shown up in many organs involved with digestion, including the liver, small intestine and the rumen. In the rumen specifically, subclinical acidosis is often pointed toward as the culprit of inflammation pathways identified in low-feed-efficient animals. The animal’s genetic response to its environment, specifically its diet, can result in subclinical acidosis in some individuals.
Subclinical acidosis, more commonly referred to as subacute ruminal acidosis (SARA), is more subtle than acute acidosis. Symptoms will not appear in the whole herd like acute acidosis. In acute acidosis, most animals go off feed, making the diagnosis straightforward.
Instead, in SARA, individual animals will show symptoms. These symptoms include reduced feed intake, lowered weight gain, potentially lameness and some undigested grain in the manure. These are all very subtle signs of acidosis, which aren’t likely to garner the attention of pen riders when displayed only in some individuals. However, the more individuals experiencing SARA, the bigger the impact will be on overall herd performance. Reduction in production performance results in costly economic losses.
So, what can a producer do to prevent SARA and improve production performance?
First, reduce ration variability through feed testing. Start a routine of analyzing all feed ingredients and adjusting rations accordingly. Differences in grain or energy sources of the diet and forage quality changes can lead to acidosis when inclusion rates are not changed to accommodate variability.
Forage variability can be attributed to a host of factors, including growing conditions, fertilization protocols, cutting heights, cutting times and storage conditions. Our lab has also seen variation across feed ingredients generally considered more homogenous. In dried distillers grains plus solubles, for example, crude protein can vary from 25% to 38%. That range for protein also doesn’t consider high-protein varieties at some ethanol plants where protein can be above 50%.
Therefore, it is more important to ensure rations maintain consistent levels of fiber, energy and protein – as opposed to consistent inclusion rates of ingredients. These adjustments can help prevent SARA. Precisely meeting animal nutrient requirements can also avoid the economic costs of overfeeding or underfeeding. The variability of the ration itself can also be analyzed over time to ensure the ration remains constant.
Second, ensuring adequate mixing of the ration can help prevent acidosis. If animals can sort, they will be more likely to experience acidosis from overconsumption of concentrates in the diet. Ensuring adequate mixing of the ration means ensuring proper ratios of ingredients. Additionally, not overfilling the batch mixer is one key to ensuring rations are mixed properly. Sampling rations as they come off the feed wagon and analyzing the beginning, middle and end separately can be a good way to check if there are any mixing errors.
Third, along with a uniform ration, consistency of feeding frequency can also reduce the prevalence of SARA. Cattle should be fed at least twice a day to prevent competition at the bunk. The timing of feeding should also be kept constant. This ensures regular intake and rumen activity. It is recommended to feed within the same 15-minute period each day.
Implementing a more meticulous feed management system can save money in several ways. First, by reducing feed waste through overfeeding or underfeeding animals. Second, by reducing individuals experiencing SARA and maximizing the production performance of the herd, thereby reducing economic losses due to poor production performance. Finally, by reducing the incidence of acute acidosis, thereby mitigating death losses and vet bills.
While most of the literature linking inflammation response to feed efficiency is focused on genetic divergence, phenotype is always genetics by environment. Diet is a large environmental factor, especially when considering the rumen interface. So, while researchers continue their search for genetic markers of feed efficiency, producers can use precise ration management to reduce SARA and allow cattle to reach their current genetic potential.
