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close this bookBetter Farming Series 43 - Feeding Animals on Straw (FAO, 1995, 30 p.)
close this folderPractical experiences
View the document(introduction...)
View the documentRate of adoption in different countries
View the documentPractical advice for extension workers and farmers
View the documentAlternative uses of straw
View the documentOperation plan for the year
View the documentFeed resources
View the documentSupplementation
View the documentFeeding of treated residues
View the documentProblems in applying technology
View the documentSystematic testing - the small pilot project
View the documentA critical consensus

Supplementation

Correct supplementation is of great importance for obtaining the full benefits from feeding straw, whether the excess feeding or the treatment approach is applied. This point tends to be neglected while too much importance is given to the effect of treatment per se or - with the excess feeding approach - getting the animals to eat more straw.

This is wrong. Oilseed cakes or oil- meals from seed cotton, soybean or sesame, for instance, are good supplements. Cereal brans and polishings may also be used. They should be used together with a supplement of green fodder, preferably from legumes. Grain from rice, wheat, barley or maize is not a good supplement and should only be fed in very limited quantities. The oilseed cakes will help the animal make better use of the straw but, as a rule of thumb, if oilseed cakes or grain constitute more than one- fifth of the total feed, the animal will tend to make inefficient use of the straw.

Data from an experiment conducted in China illustrate this general principle. The objective was to discover the effect of using cottonseed cake to supplement fattening animals which had access to all the treated straw they could eat.

Supplementing cottonseed cake

Liveweight gain obtained by supplementing different quantities of ammoniated straw with cottonseed cake is shown in the following table.

Liveweight gained with cottonseed cake supplement

Feed consumed

Cottonseed cake supplement

Ammoniated straw

Daily liveweight gain

0 kg

6.2 kg

250 g

1 kg

6.2 kg

600 g

2 kg

5.4 kg

700 g

3 kg

5.2 kg

840 g

4 kg

3.5 kg

940 g

It can be seen that there is a very good response to the first 1 kg of cottonseed cake, as the animals increase their daily liveweight gain from 250 to 600 9. As 1 kg of cottonseed cake is less than one- fifth of the total quantity eaten (1 kg of cottonseed cake and 6.2 kg of straw) there is no effect on the quantity of straw consumed, which remains the same at 6.2 kg, with and without cottonseed cake. However, 2 kg of cottonseed cake constitute more than one- fifth of the total diet and the amount of straw eaten is reduced from 6.2 to 5.4 kg, and this tendency continues as the level of cottonseed cake is increased to 3 and 4 kgs. It drops to as little as 3.5 kg of straw with 4 kg cottonseed cake.

It can of course be argued that the animals are increasing their daily weight gain by eating more cottonseed cake. But normally straw is much cheaper than oilseed cake and grains and so it has to be calculated carefully whether, in a particular case, it makes economic sense to go beyond a supplement of 1 or 2 kg. This applies in both the excess feeding and straw treatment approach.