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This article was published in 1961
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Drought Feeding of Sheep
REPORT ON BURDEKIN DROUGHT FEEDING UNIT
P. McINNES, B.V.Sc., Livestock Research Officer, Glenfield
Study of The Comparative Utilization of Low Quality Roughage
Further investigations of the utilization of low-quality roughage have been made during the past year. Low quality roughage such as straw or poor-quality standing dry grass is low in protein content and the amount consumed by sheep can fall below ½lb. per day. In a recently conducted trial, straw of 2.7% crude protein (C.P.) was fed to a group of 16 merino wethers. Deaths occurred from the 6th week and there were no survivors by the 20th week. The majority of deaths (75%) occurred during the first 12 weeks of the trial. Previously, when straw of 3.5% C.P. was fed, 25% of the sheep had died before the end of a 26 weeks trial, and the mean body weight of the group fell from 95lb. to 64lb. From these and other trials it can be concluded that a sole diet of low quality roughage cannot sustain sheep during a prolonged drought.
Early experiments showed that the addition of protein rich supplements to low-quality roughage diets greatly reduced weight losses and the number of deaths;e.g. 3.1oz. of linseed meal per head per day; 6.1oz. of lucerne chaff per head per day. Another approach in studying the increase in utilization of low-quality roughage was taken in a trial which was completed recently.
Straw of 2.7% C.P. and roughage mixtures (mixtures of straw and lucerne chaff) of 5.2% and 7.6% C.P. were fed with and without a supplement of 3oz. of wheat per sheep per day to groups (16 sheep) of 4 tooth merino wethers for 26 weeks. While there were no survivors in the group led straw alone there were approximately 70% when the supplement was fed either daily or twice weekly. When the 5.2% C.P. roughage mixture was fed alone, there were 44% survivors compared to 80% when the supplement was fed. There were 100% survivors when the roughage of 7.6% C.P. was fed with and without wheat.
When the C.P. content was increased from 2.7% to 7.6% by mixing 2 parts of straw with one part of lucerne chall the intake of roughage increased by 1.2lb. per sheep per day. This meant that the group fed the mixture actually consumed 1.16lb. of straw per head per day compared with 0.50lb. for the group fed the straw alone.
During the same trial a comparison was made between feeding cereal chaff of 7.6% C.P. and the roughage mixture of the same C.P. When the cereal chaff was fed ad lib. the mean intake of the group was 2.30lb. per day and the mean liveweight increased by 7lb. The mean intake of the group fed the roughage mixture was 1.72lb. daily and there was a mean loss of weight of 13lb. All sheep survived in both groups. When the intake of chaff was controlled so that two groups consumed the same amounts of roughage, the group fed cereal chaff had a smaller mean liveweight loss (5.4lb) but there was no difference in the number of survivors.
Effects of Drought on Ewe Fertility
Maiden merino ewes, 18 months old were subjected to drought rations for 6 months and then divided into 2 groups of approximately 110 sheep. One group (Group 1) was mated immediately while the other (Group 2) was allowed to recover under ideal grazing conditions for 5 months before being mated. Some of the results are summarised in the following tables I and II:—
TABLE I
| Group | 1959/60 | 1960/61 |
|---|---|---|
| Group 1 | 65% | 83% |
| Group 2 | 72% | 75% |
% Ewes producing lambs which lived 24 hours.
TABLE II
| 1st Year | 2nd Year | % |
|---|---|---|
| L.R. | L.R. | 29 |
| L.NR. | L.R. | 29 |
| NL. | L.R. | 22 |
| L.NR. | L.NR. | 8 |
| NL. | L.NR. | 6 |
| NL. | NL. | 5 |
Classification of breeding performances of ewes subjected to drought conditions for 6 months and mated immediately thereafter. L. — Lambed; NL. — Did not lamb; R. — Reared lamb; NR. — Did not rear lamb.
The mean body weight of the ewes after the drought conditions was about 52lb. in Group 2. Within 25 weeks this mean weight had increased to 95lb.
During the drought feeding some of the ewes had been placed on a diet containing a higher crude protein. The only occasion when there appeared to be any significant difference in the breeding performance was in the first mating of Group 1. Of the ewes which had been fed higher-quality protein diet 83% lambed while of those fed the lower-quality only 62% lambed.
As yet there are further results to be analysed, but there appears to be a general conclusion that drought conditions do not have a permanent effect on the fertility of the ewe. The percentage of ewes which lambed from the first mating of Group I (sic) was probably not much lower than what is experienced by many graziers with maiden ewes. However, from the results of the ewes fed the higher protein diet during the drought. it would appear that drought conditions do have some effect on the lambing % of the ewes which are mated immediately after a drought.
Maintenance Requirements of Some Breeds of Sheep
Taking as a guide 55% of the British Standards, Corriedale, Polwarth, and Border Leicester x Merino wethers were fed levels of energy which maintained them in condition without loss but resulted in a mean liveweight fall of approximately 5lb. This loss has yet to be corrected for wool growth. The mean liveweight of the breeds and the amounts fed were as follows:—
TABLE III
| lb S.E./week | Weight at Commencement (lb) | |
|---|---|---|
| Corriedale | 5.1 | 83 |
| Polwarth | 4.7 | 96 |
| Border Leicester x Merino | 5.3 | 103 |
The level of energy fed and mean body weights of the breeds
When the breeds were fed a level which was one pound less of starch equivalent per week than shown in the table, they held their condition, but there was a mean body weight loss of approximately 12lb. All sheep survived these treatments. However, when the level of energy was reduced by two pounds of starch equivalent per week there were losses in the Corriedale (3/16) and Polwarth (2/16) groups, but all in the Border Leicester x Merino groups survived. Most of the sheep lost condition and there was a mean liveweight fall of approximately 221b. These liveweight falls have not been corrected for wool growth.
As the level of energy was determined on mean body weight of the breed before randomising into groups, the trial was not intended to be a comparison of breeds. It would appear that the highest energy levels fed, that is the levels in the table, are very close to maintenance requirements of the breeds.
Recovery of Merino Wethers on a High Energy Ration
Forty merino wethers which had been fed low-quality rations for six months were allowed to recover on a high energy mixture of 16⅔% lucerne chaff, 16⅔% wheaten chaff, 33⅓% millet and 33⅓% barley fedad lib. for 26 days. Approximately 10lb. of mixture Was required for every 1lb. gain in liveweight.
The group was fed 1lb. 1½lb. and 2½lb. of the mixture on the first three consecutive days. They were then allowed to feedad lib. from the fourth day. The trial continued for 26 days and the mean liveweight increased from 71.2lb to 80.5lb. Approximately 16lb. S.E. per week was consumed.
The amount of feed to provide the bodyweight increase was high and would be costly if the fodder was purchased. From these results, it would be reasonable to conclude that it may not be economic to place sheep solely on a high quality hand feeding programme immediately after a drought, for such purposes as conditioning for market.
Feeding Trefoil Seed
A trial occupying 17 weeks was conducted with two groups of seven merino wethers which were fed a low-quality roughage (2.6% C.P.)ad lib. with either a supplement of 4oz. of linseed meal or 4oz. of trefoil seed per head per day.
The crude protein content of the Linseed Meal was 40.5% and the Trefoil Seed 38.3%.
The roughage intake of both groups was approximately 1lb. The fall of mean liveweight in the group fed the linseed meal was 4.5lb. in comparison with a fall of 8.4lb. in the group fed the trefoil seed. All the sheep survived in both groups.
As there was no significant difference between the treatments the results indicate the advantages of grazing sheep on trefoil seed And burr. This form of grazing has proved a great "standby" for graziers in the Western Districts of N.S.W. in dry periods and during droughts.