One of the most critical parts of managing a flock is how replacement ewe lambs are developed. Too often we see the ewe lambs left with the market weathers for an extended time. Many might question why this is an issue. What we need to know is that ewe lambs that are left on the feeder lamb diet for too long develop too much fat. This fat settles around their organs, including the uterus and the mammary tissue. Research has shown that too much fat deposition in the udders of ewe lambs and subsequent inferior mammary development can negatively impact their lifetime milk production, which ultimately effects the bottom line. Other issues that may occur if there is too much fat around
organs include decreased space for the uterus and rumen, as well as an increase of the animal’s internal temperature of that animal that can decrease fertility. Giving birth to small, weak lambs or excessively large lambs are also possible outcomes if ewe lambs are allowed to get too fat.
Producers often wonder when they should pull the ewe lambs and what should they be fed. These answers will be determined by breed, farm management and location, farm goals, etc. However, a good rule of thumb for an average-size sheep would be to pull the ewe lambs from the market pens no later than 90 pounds. This target weight could be lower for smaller framed sheep or hair breeds that can get excessively
fat. Ultimately, the ewe lamb should reach 70% of her adult body weight by breeding, and ideally up to 75% of her adult body weight by lambing around 12 months of age. When selecting replacements, opt for multiple birth, born early in the season (means the ewe settled quickly), high performance, and sound conformation animals.
When to breed
The one thing that most sheep producers agree on is to breed ewe lambs to deliver around 12 months of age as they believe it increases the animal’s lifetime productivity. Interestingly, the Lamb Resource Center advises that the importance of breeding lambs as yearlings is early puberty. According to research data, early puberty ewes have a greater instance of twinning over their lifetime. Where we see a breakdown in longevity of these ewe lambs that deliver as yearlings is when they are managed like the rest of the ewe flock. Yearling ewes are expected to mature and grow lambs at the same time, which will require a bit more attention than the older ewes.
In many cases where ewes are managed as part of a large, multigenerational group, the youngsters will fall out of the flock before their 2nd breeding season. In a range flock, management styles will likely differ based on region. Producers should understand that recommendations for the Midwest may not apply everywhere, and it is important to match management to individual and unique farm goals.
When determining nutrition needs for ewe lambs, one formula does not fit all farms. Not all ewes will thrive on free choice or limit-fed grass hay and a ½-1 pound of corn. The Nutritional value of the feeds on hand, the genetic potential of the flock, and the operation’s management style should all be considered when ascertaining the best feed formulation for the flock.
Research has shown that ewe lambs don’t need to be pushed as hard as market weathers. Lower and slower might be more appropriate, providing the pace isn’t too low and slow as the younger animals might not reach puberty and their proper weight before breeding. The general recommendation is that animals should be gaining a minimum of .4 lbs/day before and throughout breeding. This recommendation varies slightly from the .5lb/day suggestion by Dr. Thomas from the University of Wisconsin. Research has also shown in the first 5 months of life, replacements should be fed at no more than 65-75% of their maximum gain potential, with some experts recommending 50%. As stated earlier, breed, weight and age at weaning and production environment, all influence how well ewe lambs will grow.
Baselines, goals and development
It’s important to establish a baseline or current status of the flock, and the goal for the flock before determining how to best develop ewe lambs. At the same time, when raising replacement rams, it should be noted that overconditioning them can be detrimental to their breeding potential, just like overconditioning ewe lambs can affect their lifetime milk production.
While there is far less consolidated research on developing replacement does, some general information to note is that by the time overconditioning is evident on a goat, they are exceedingly fat, as goats tend to lay fat down internally first as opposed to sheep, who tend to lay down external fat first. Considering this difference, goat nutritional needs are higher than sheep nutritional needs, which means if they will be kidding as yearlings, they should be on a higher plane of nutrition than a replacement ewe lamb, especially in harsher winter climates. For this reason, a little overconditioning on a doeling that is expected to kid as a yearling is not the end of the world. They tend to lose that condition quickly post-kidding. Contrary to popular belief, goats are much more susceptible to health issues than sheep. Because the goat industry is so varied, plans most definitely should be determined based on the farm goals and current conditions.