29 January 1999

Digestibility balance

LIVESTOCK should be able to make more use of maize if French breeders succeed in altering fibres in the plant.

Researcher Michèle Champion of the lAlliance Elevage animal nutrition research station says work has begun to select varieties with different fibre mixes to improve digestibility.

Breeders want to increase fibres such as hemicelluloses which are relatively digestible, but limit tougher fibres such as lignin which as less digestible. But a delicate balance must be found as lignin is responsible for plant stiffness and, therefore, prevents lodging, says Ms Champion.

Also, if maize is too digestible and starch released too quickly, this could reduce rumen pH and appetite. More starch would then pass into the small intestine, where it cannot be fully used, and eventually excreted increasing waste.

To overcome this, breeders are looking to alter the two types of fibres in the seed coat; one of which is quick to break down, while the other is slow. This might allow producers to select a highly digestible variety which matches the herds requirement for slow or fast starch release, depending on the ration being fed. &#42