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:

How Acidosis Causes Laminitis

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.

Cows at Risk

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.

Acidosis Prevention

Preventing a significant pH drop in the rumen is a key component in laminitis control. Here are preventative steps you can take:

  • avoid overloading the rumen with rapidly fermentable carbohydrates, especially in late pre-calving and early lactation;
  • feed grain in small portions and no less than four times a day if the amount is significant. Whenever possible, don't separate rapidly fermentable carbohydrates from forage;
  • feed the same type of grain or carbohydrate in the pre-calving ration that you use in the milking ration. This lets an adapted rumen microorganism population develop. These microflora will be in a better position to handle the energy-dense ration of early lactation;
  • optimize forage intake and forage quality to reduce requirements for concentrate. A minimum of 45 percent forages in an early-lactation ration is recommended and more, if possible, is even better;
  • since cows ingest kilograms, not percentages, have the ration evaluated on a cow's ability to ingest specific amounts of the ration. The minimum forage neutral detergent fibre (NDF) intake as a percentage of bodyweight should be 0.85. The minimum total NDF intake as a percentage of bodyweight should be 1.2;
  • avoid excessive levels of non-fibre carbohydrate (NFC) since fibre digestion and acetic acid production can be depressed, potentially leading to acidosis. The NFC fraction is highly digestible and can be quickly fermented in comparison to NDF. In most cases, a level of NFC between 32 and 38 per cent is considered adequate;
  • match the fermentation rate of carbohydrates with rumen availability of protein. For example, a high-quality alfalfa haylage will fit better with high-moisture corn or barley than dry corn in terms of degradation rate.

Feeding Management

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:

  • factors that can cause slug feeding of the TMR could be limited bunkspace, limited feed access time, inconsistent feeding schedule, bunk competition, limited quantities of feed, infrequent TMR push up and heat stress;
  • bunk space should be greater than 0.5 metres per cow to prevent competition. Feed availability should be greater than 20 hours per day. The total ration served to the cow should be five to 10 per cent more than required to prevent feed shortage;
  • feed sorting can occur when a TMR contains large forage particles and the cow leaves them behind. True forage and fibre consumption can then be less than optimal;
  • potential ways to alleviate problems include feeding smaller amounts of TMR more frequently, adding less course forage, using more high-quality hay, processing corn silage and adding water to a dry TMR.

Other Key Factors Affecting Hooves

Environment

A herd's environment can impact on the acidosis and laminitis incidence. A high incidence of laminitis should lead to investigation of these possibilities:

  • heat stress;
  • lack of exercise;
  • inadequate stall space and stall design;
  • excessive curb height;
  • overexposure to concrete floors;
  • insufficient resting time.

Hoof Trimming

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.

The Big Picture

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.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: Mario Mongeon - Livestock Specialist/OMAFRA
Creation Date: September 2003
Last Reviewed: September 2003