Healthy balance

Feed Conversion Ratio (FCR) is an important measure livestock farmers use to measure their business efficiency. FCR is the ration of the mass of feed the farmer fed an animal compared to the mass of body weight the animal has gained. An FCR of 2.3 would mean an animal has consumed 2.3kg of feed for every 1kg of body mass it has gained. Feed cost is the single biggest expense a farmer has in raising animals, typically this accounts for about 60 to 70 percent of his total expenses. On the other hand selling live animals is his biggest source of income. Therefore FCR is essentially a comparison between the farmer's biggest expense and biggest source of income. Naturally to say, any profit minded farmer will strive to lower the FCR of the animals he is raising.

There are several factors influencing FCR, but three of them tend to stand out.

The first is the type of animal. Chickens have much lower FCR values than sheep; animals that are slaughtered at a younger age have lower FCR values and different breeds of cattle will have different FCR values. The second factor is the type of feed. Animals being raised on feed with a higher nutritional value will have lower FCR values.

The third factor is the environment within which the animals are kept. Animals placed in an environment which they perceive as being comfortable will have higher FCR values.

As a point of reference, if all the factors mentioned above combine favourably, chickens will have FCR values in the range of 1.6 to 2; pigs in the range of 2 to 3; sheep in the range of 5 to 7; and cattle in the range of 6 to 10.

Environmental influences
The biggest factor amongst environmental influences is the environmental temperature. During the process of metabolism, the feed consumed by the animal is converted into energy. Not all the feed can be metabolised and consequently some of the consumed energy is excreted. Metabolism also generates heat, some of which the animal will use to maintain a body temperature in the region of 37°C to optimise physiological processes.

The air temperature of the environment within which the animal is kept will mostly be different from the animal's skin temperature, which results in a heat exchange between the animal's skin and the environment. The magnitude and direction of this heat exchange is dependant on the magnitude of the temperature difference between the animal's skin and the surrounding air temperature or the ΔT. A large ΔT will lead to a large heat loss, while a small ΔT will lead to a small heat loss.

For survival it is of the utmost importance that the animal maintains a balance between its energy intake (feed consumption) and energy loss to the environment. Failing to do so will increase of decrease its core temperature which will negatively affect its physiological process and could ultimately lead to death.

When animals sense a large heat loss to the environment (large ΔT) they respond by increasing energy intake (increase feed consumption). Sensing a low energy loss, the response is the opposite.

These responses to environmental air temperature fluctuations are well developed natural defence mechanisms. However, the same is not true about the farmer's profitability, which is dependant on the portion of metabolised energy that is available for growth. The larger the portion, the lower the FCR. Whenever the animal increases or decreases feed consumption in order to maintain an energy balance with the environmental air, the portion of energy available for growth is decreased.

Within Munters we are extremely aware of this direct link between environmental air temperature and FCR and have therefore developed many different products and solutions that will enable farmers to keep control of the air temperature (as well as other environmental factors) inside confined housing structures. This enables them to keep their animals comfortable, lower the FCR and maximise their profitability.

Wouter Claassens graduated as an Agricultural Engineer from the University of Pretoria, South Africa, in 1996. He joined Munters in 2001 and currently holds the position of Global Technical Manager, managing the Engineering and R&D functions within the AgHort business area of Munters.