Purdue University Cooperative Extension Service Lafayette, Indiana
Mimeo AS-329 June, 1965
Accelerated Lambing Program
J. B. Outhouse, K. J. Drewry, Henry Mayo and Martin Stob, Department of Animal Sciences
If the sheep industry is to survive in the United States, it must compete economically with other farm enterprises. One way in which this can be done is to increase the productivity of the ewe flock through an accelerated lambing program. In such a program, the periods between lambings are shortened and the lamb crops are produced every 8 months instead of every 12 months.
Sheep are considered to be seasonal breeders. Ewes are normally bred during the fall months, producing a lamb crop during the spring. The gestation period varies from 140 to 150 days or roughly 5 months. Ewes are permitted to nurse their lambs to weaning for an additional 4 to 5 months.
They are then given 2 to 3 months in which to rest. During this period, they usually become too fat thus reducing their reproductive efficiency for the next year either because they fail to breed or because they have difficulty at lambing time. Under such a system, the average flock produces from 125 to 150 lambs per 100 ewes bred.
Three Lamb Crops in Two Years
Recent research at many experiment stations indicates that this cycle of events can be altered to the point where a flock may produce a new lamb crop every 8 months, or three lamb crops in two years . Instead of 125 to 150 lambs per year, 100 ewes would be capable of raising from 375 to 450 lambs in two years or an average of 187 to 225 per year.
This would permit a much greater return on the same investment with very little
increase in feed costs, labor, or equipment.
In addition, it would tend to even out the supply of lambs to the packer and the consumer and permit sales to be made in seasons when lambs are normally scarce and prices are more favorable.
Reasons for an Accelerated Lambing Program
There are three reasons why this increased productivity is both practical and beneficial. First, the productive life of the average ewe is six years, extending from approximately 18 months to 7 1/2 years of age. During that time, she would normally produce six crops of lambs. Under an accelerated program of three lamb crops every two years, she could produce nine crops of lambs in the same time, an increase of 50 percent in her productivity.
Secondly, research shows that the milk production of the ewe reaches its peak at about 4 weeks following lambing and steadily declines to approximately 50 percent by the 10th week and considerably less by the 15th week. After 15 weeks, the ewe is not much more than a companion to the lamb and she tends to contaminate the pastures with parasite eggs thus reducing his growth rate.
Under an accelerated program, the lambs should be weaned at 60-70 days of age. This will benefit the lamb, permit the ewe to be rested briefly, and her milk supply will be dried up before she is bred for another lamb crop.
Lambs weaned at 60-70 days of age will require better management and will need