Feet and Feed - Attention to Transition Cow Management Reduces Laminitis Risk
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Sore feet put cows off their feed, and poor appetites mean lower milk production. You can reduce the risk of one common cause of lameness by ensuring your animals eat right during the transition stage.
Laminitis, a painful inflammation of tissue inside the hoof called the laminae, hinders cows from standing and walking. They eat less and produce less-particularly in barns with robotic milking systems. Recent studies have shown affected animals produce up to 2.8 kilograms less milk per day. That's $1.85 out of your pocket.
Research has clearly linked certain foot problems, particularly laminitis, with rumen acidosis. You can help ward off acidosis, and thus laminitis, with careful management of transition cows, paying particular attention to their diet just before and after they calve. That's one of the key messages from a recent laminitis symposium in Phoenix, Arizona. Let's take a closer look at this disease and some of the other advice gleaned from the symposium:
Rumen pH is normally close to neutral at 6.5 but it can vary according to ration composition and feeding management. Rations rich in concentrate, especially rapidly fermentable carbohydrates such as grain, can greatly decrease rumen pH. Some rumen micro-organisms will readily convert starch in these rations to lactic acid, leading to a lower acidic pH. Sub-acute laminitis occurs when the volatile fatty acid load in the rumen is excessive.
A rumen acidosis episode can occur long before signs of laminitis or sub-acute laminitis become visible. As rumen acidosis occurs, the rumen bacteria population changes and the fibre digester organisms tend to die. This whole process leads to the animal 's bloodstream absorbing compounds known as metabolites, endotoxins and histamines. These compounds can affect the blood supply of the growing hoof wall, often leading to clinical or sub-clinical laminitis.
Ration composition usually evolves according to the stage of a cow's production cycle. The composition of the rumen's micro-organism population also varies with the type of feed ingested.
Upon dry-off, the cow usually gets a high-forage ration-less energy dense than the lactation ration. This diet contains less fermentable starch. The lactate-producing bacteria population declines, as well as the population of bacteria converting lactate to compounds such as acetate or propionate, which are useful to the cow. A second effect of a lower energy diet during the early dry period is the reduction of the rumen wall's ability to handle rations rich in fermentable starch-as much as 50 percent, according to one study.
Cows are most at risk for acidosis immediately after calving and up to 120 days afterwards. Soon after calving, they're often fed a high-energy, higher concentrate ration. Their rumens take time to adapt to the new ration. Dry matter intake hasn't yet peaked and forage consumption can be depressed. The forage-to-concentrate ratio can become less than optimal.
A build-up of acidic compounds in the rumen can lead to its acidification. Metabolic acidosis occurs if the amount of organic acid produced exceeds the ability of the liver to metabolize these compounds.
Preventing a significant pH drop in the rumen is a key component in laminitis control. Here are preventative steps you can take:
Lots can go wrong in ration formulation, feed delivery and bunk management. Errors in these areas can lead to acidosis-especially if errors are repeated. Key areas to check include feed sampling and analyses, dry matter adjustments, ingredient feeding rates, forage and total mixed ration (TMR) particle size, grain dry matter and degree of processing, and TMR over-mixing that reduces particle size.
Rumen pH has been shown to become more acidic after meals. The rate of pH decline increases as meal size increases and dietary NDF concentration decreases. Any bunk management practices that cause cows to eat fewer and larger meals more quickly may promote acidosis and, potentially, laminitis. Here are items to consider:
Other Key Factors Affecting Hooves
A herd's environment can impact on the acidosis and laminitis incidence. A high incidence of laminitis should lead to investigation of these possibilities:
Regular, well-performed hoof trimming can increase a cow's productive life by up to one lactation. Routine trimming can stimulate horn-producing tissues and accelerate production of new healthy horns. Trimming once or twice a year is recommended. The ideal time to trim would be at dry-off and then in mid-lactation. Monitor problem cows more frequently.
If you have a significant incidence of this complex disease in your herd, you need a whole-farm management review to identify weak points and correct them. This review would include evaluating your herd for lameness (scoring), stall usage, heifer management and nutrition.
This article appeared in the September 2003 Ruminations column of the Ontario Milk Producer.
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