Last update: April 10, 2012 07:31:33 AM E-mail Print

 

Sheep find thin honey-locust pods palatable

P.L.LE ROUX 

 

In an experiment at the Grootfontein College of Agriculture it was found that the readiness with which sheep feed on ground honey-locust pods depends on the thickness of the pods.

In the previous article it was stated that the pods of the honey-locust tree could be stored for long periods for possible use during periods of drought. Experiments were therefore conducted in which only ground pods were fed to sheep in order to determine the palatability and general nutritive value of this feed.

In one experiment six-tooth Merino wethers in good condition were taken off the veld and fed lucerne hay for six weeks to accustom them to eating from feeding stalls. Their ration was then changed gradually from lucerne hay to ground honey-locust pods. All the results showed that the wethers failed to eat sufficient quantities of the ground pods to sustain themselves. The average intake per sheep per day was only about 18 oz. as compared with about 34 oz. of lucerne hay before the change whilst the average live weight of the sheep was about 70 lb. As a result, the sheep deteriorated rapidly in condition and in six weeks they were so emaciated that the experiment had to be ended. The ground pods cannot therefore be regarded as being very palatable.

 

COMPARISON

It has been found that different honey-locust trees can yield a variety of pods. Considerable variation may also occur in the pods obtained from one and the same tree- in different years. So, for example, the thickness of the pods may vary from paper-thin to thick.

The first group of trees planted at the Grootfontein College of Agriculture for experimental purposes are already 18 or more years old. The pod yields of these trees varied widely from tree to tree. Two of these trees produced good yields (yields of 480 lb. of pods having been obtained from each individual tree per season) and it was noted that the pods from the trees concerned, differed appreciably. The pods from one tree were fairly thick, while those from the other could be described as being on the thin side. The ground pods from these two trees were duly compared in feeding trials. It was found that the eagerness with which the sheep ate the ground pods depended on the thickness of the pods and it was observed that they preferred thin to thick pods. For example, sheep with an average live weight of 80 lb. ate an average of 22 oz. of thick pods daily as compared with 26 oz. of thin pods.

The question then arose as to what this difference in palatability should be attributed to. Only work done at a later stage showed that the ground seed of the honey locust is very palatable, while the surrounding husk, i.e. the pod without the seed is much less palatable. In thick pods the proportion of seed to pods without seeds is smaller than in thin pods; in other words, in the same weight of pods, there are more seeds in thin pods than in thick ones. Since the seed constitutes the more palatable part of the pod, it is clear that the thin pod is more palatable to stock.

Another difference between the two types of pods is that the digestibility of the crude protein differs appreciably. In the thin pod, the digestibility of crude protein is 50% as compared with 38% in the thick pod. Since crude protein is more digestible and the sheep prefer the thin pod, it is a more suitable type of fodder than the thick one.

 

RATIONS

As the pods are relatively unpalatable and irritate the nasal cavities of animals when ground, they should preferably be given to sheep in combination with other feeds. The pods are deficient indigestible crude protein, which should be supplemented. The total digestible nutrients are high, and feed can therefore quite profitably be supplemented by feeding roughage.

As an example of the proportions in which the ground pods may be mixed with other fodder. The following rations for sheep are suggested. Taking into account the fact that 0.17 lb. of digestible crude protein and 1.7 lb. of digestible nutrients a day are required as maintenance ration by a sheep of 100 lb. live weight, the following fodder mixtures could be used to advantage:-

(i) 100 lb. of ground pods mixed with 200 lb. of good quality lucerne hay and 300 lb. of veld grass hay of good quality.

(ii) 100 lb. of ground pods mixed with 83 lb. of good quality lucerne hay and 100 lb. of oat straw.

 

Three pounds per day of these mixtures should be fed to sheep of 100 lb. live weight. If the lucerne is of poor quality, more lucerne but a smaller quantity of veld grass hay or straw should be added to the mixture.

Where there is a shortage of fodder oats, ground pods may be partly substituted for this constituent in cow rations. Further experiments still have to be conducted to determine the palatability of the pods and their effect on the production of milk etc. of dairy cows before any definite recommendation can be made in this connection.

 

Published

Farming in South Africa 35 (2)