Brady Campbell, Program Coordinator, OSU Sheep Team
A few months ago
as a part of the ‘Let’s Grow’ initiative sponsored by the American Sheep Industry Association, Dr. Reid Redden, Sheep and Goat Specialist with Texas A&M AgriLife Extension, presented a webinar focusing on the seasonality of the US lamb industry. This webinar was an overview of the recently published industry white paper that can be viewed fully by viewing this link. During his presentation, Dr. Redden covered both Traditional and Non-traditional markets that US producers have access to. He also presented several figures that outlined the time of year that lamb is most commonly consumed as well as when each specific cut of lamb is consumed. Rather than focusing on these highlights from Dr. Redden’s presentation, toady we will be focusing in on the production aspects of aseasonal or out-of-season breeding.
According to a 2011 USDA report, approximately 85% of all US lamb is produced in the first five months of each calendar year (January – May), with virtually no lambs born during the summer months, and a few born during the fall months as shown in the figure above. The reason for this is that sheep are naturally short day breeders. This means that as day length decreases, there is an increase in exposure to darkness. Melatonin, an important hormone that signals for the beginning of the breeding season, is produced at night. Therefore, as melatonin concentrations increase, there will be an increase in the likelihood of ewes coming into heat depending upon breed. Some breeds are more seasonal or more sensitive to day length and concentration of melatonin than others. Generally speaking, especially for producers in the state of Ohio, Peak breeding season is September through December. However, this breeding window can vary depending upon your distance to and from the equator.
Location not only plays a roll in the ability for your ewe flock to begin cycling and the breeding season, but also the ability to efficiently produce fall born lambs. Take a moment to think about where a majority of the US sheep production takes place. Western range lands and inter mountainous regions tend to be the areas in which a majority of US lamb is produced. When considering the environment in which these animals are housed (i.e. extreme environmental conditions and limited resources), aseasonal breeding may not be a viable option for these producers. However, for producers in the eastern US, especially Ohio, aseasonal breeding may be a viable options for producers to consider as this type of production system is a practical consideration in producing US lamb to fill the industry gaps. Now that you are thinking about implementing this on your own farm, what are some management challenges that you will have to consider.
First and foremost, nutritional status of your ewe flock will play a greater role during aseasonal breeding than it will during fall or normal breeding. In order to increase your chances of successfully achieving out-of-season breeding, ewes must be in good body condition. Industry experience has shown that ewes in poor body condition, on a poor plane of nutrition, or females that have just experienced a hard lactation period will struggle to become pregnant during the spring breeding window. This of course makes sense when we consider the hierarchy of nutrient utilization (maintenance, development, growth, lactation, reproduction, fattening). Therefore, in order to begin your quest of aseasonal breeding, be sure that your animals are in good condition.
Now knowing that the plane of nutrition is critical for spring breeding, we also must consider the availability of high quality feedstuffs during fall lambing and winter lactation. Pasture based systems can be well suited for fall lambing systems, especially those using annual forages. Keep in mind when you will be grazing these forages. Depending upon the time of year (winter), these forages will not be growing back. Yes, these forages will be of high quality, but you must consider what your next plan will be when you run out of forages. You also have the option to feed your ewes grains and stored forages like it would be practiced in a winter lambing system. Therefore, some questions may be will you wean your lambs or will you provide some sort of supplement? Both are two viable options among many others.
So now that you have established a proper body condition that you need to have your ewes in and you have an idea of what diet you would like to be feeding, now you need to consider how you will be altering your current breeding system to turn it into an aseasonal breeding program. First, you need to make sure that you have enough ram power meaning that you have enough rams for the number of ewes that you will be breeding. Remember, ewes are not the only sex that is affected by seasonal breeding. For some breeds, rams may exhibited low levels of libido outside of their normal breeding season. With lower libido and potential semen production, using fewer ewes per ram (1 ram per 10 ewes) will also be of benefit. Research has also shown that the introduction of a male, coined the “ram effect”, will also help ewes naturally come into heat. To do this, simply place the ram with the ewes about 1 month prior to the desired breeding date. Ewes may ovulate, but often run through a ‘short cycle.’ After this cycle, ewes should come into heat. If you are concerned about using your breeding ram to induce the initial cycling, consider using a teaser ram for this job.
In addition to the ram effect, there are other options available to aid in developing an out-of-season breeding flock. The use of exogenous hormones by the use of a CIDR and injections can also be of benefit as they will aid in both the synchronization of ewes as well as the induction of estrus. However, using these types of technologies have demonstrated conception rates of 30%-50% in strictly seasonal breeds of sheep, but show more promise when used in aseasonal breeds as shown by a 50%-80% conception rate. A down fall of this technology would be the additional cost associated with each ewe. In addition, with the variation of conception rates, the lower the conception rate the greater the cost is per ewe that produces a lamb. Other options to aid in the development of a fall lambing flock is physically altering the lighting schedule of your ewe flock and genetic selection. Alteration of lighting schedules may be difficult as ewes must be shut indoors without access to the sunlight as a means to help increase the level of melatonin in their systems. As for genetic selection, currently the sheep industry does not have a data tool that can be used as a means to select or measure for aseasonal breeding. However, there has been success with producers retaining ewes within their own flock that are known to have parents that are successful with out-of-season breeding. As a note, these options will be covered in greater detail in an up-coming Ag-note.
With seasonality being an issue for a majority of the US lamb industry, there is certainly room for growth in this spectrum of the industry. Understanding the additional costs and management decisions associated with this type of lambing system is key to the success of this type of enterprise. Smaller scale farmers, especially those here in Ohio and the midwest, could benefit financially from the premium demand for these types of lambs. For those interested in out-of-season breeding, I encourage you to read the white paper in detail and to contact the authors of this piece or any of the supporting OSU Sheep Team members.