Dr. Scott Greiner, Extension Animal Scientist – Sheep, Virginia Tech
(Previously published on the Virginia Cooperative Extension web page)
In winter-lambing production systems, the flock is typically managed to provide rapid early growth of lambs for early marketing. Growth rate of lambs from birth to weaning is largely determined by milk production of the ewe, which emphasizes the importance of good nutritional management during this period. Lactation is also a period in which there is opportunity to control feed costs by feeding ewes according to the number of lambs nursing. During lactation, the ewe’s nutritional requirements for both energy and protein are at their highest level. Therefore, the highest quality hays available should be utilized during this time. Alfalfa hay is an excellent feedstuff during lactation due to its relatively high energy and protein density relative to other forages. In most cases, a grain-protein supplement (such as corn-soybean meal) will also need to be fed in addition to the highest quality hay available. The needed protein content of this grain mix will vary depending on quality of the hay utilized. Generally, total rations should be formulated to contain 70% TDN (total digestible nutrients) and 14% protein for lactation (Table 2). Table 1 demonstrates the significant differences in nutrient requirements of ewes nursing single vs. twins vs. triplets. As mentioned previously, milk production of the ewe is influenced by nutrition. Research conducted at Michigan State University by Dr. Margaret Benson showed that feed intake was the most important nutritional factor affecting milk production. Therefore, diets that are nutrient-dense and highly palatable will enhance milk production.
An important aspect of nutritional management is accurately determining the quality of forages that will be utilized, most importantly hay. To properly balance rations and formulate diets, a forage analysis should be conducted on all harvested feeds (hays and silage). There can be significant variation in hays harvested from the same field from one year to the next, and from one cutting to another. Having accurate forage analysis may save feed costs and will certainly improve the ability to adequately manage the nutrition of the flock.
Splitting ewes by number of lambs nursing is an excellent management technique to minimize feed costs. Ewes rearing single lambs will require less grain supplementation than twin-rearing ewes. Similarly, triplet-rearing ewes could be provided the extra nutrition needed, if separated from other ewes. When all ewes are fed together, single-rearing ewes are likely being overfed whereas triplet-rearing ewes will be underfed. Of course, facilities and labor along with flock size will dictate feasibility of this management practice. A feasible alternative is to minimize the number of ewes raising triplets and singles through grafting. There are many methods used to graft orphan lambs to other ewes, with the use of a stanchion the most common. The largest, most aggressive lamb is usually the best candidate to graft. Grafting works best when the lambs to be grafted are similar in age to the ewe’s own lamb. Grafting a triplet lamb to a ewe with a single is most common. The grafting process should be initiated as soon after birth as possible.
Creep feeding is the practice of providing young lambs supplemental grain while still nursing the ewe. Thus, creep feeding supplements the milk produced by the ewe and can provide valuable added weight gain. This added weight gain has the most economic value for lambs managed in an intensive, early weaning production system where lambs will be maintained in a dry-lot all the way to market weight. Conversely, for lambs that will be developed on pasture throughout the spring and summer, creep feeding is of little value due to the relative expense of this early weight gain (which may be later attained on forage). Creep feeding also is beneficial for flocks with a high number of multiple births, or flocks with ewes having limited milk production.
Young lambs may be started on creep feed as early as 10 days of age. Although significant amounts of feed are normally not consumed until 3-4 weeks of age, providing access to creep feed at an early age allows lambs to develop a habit of eating dry feed, and helps stimulate rumen development. For creep feeding to be economical, lambs must consume enough feed to increase performance. Lambs should eat a minimum of 0.5 lbs. of creep feed per head per day from 20 days of age to weaning.
The creep ration need not be expensive or complex. The principle behind creep feeding is to stimulate lambs to eat and therefore promote weight gain. Therefore, highly palatable feeds must be provided. At a young age, lambs prefer feeds that are finely ground and have a small particle size. Feedstuffs high in palatability for young lambs include soybean meal, ground corn, sweet feeds, and alfalfa hay. These feeds should be replaced daily to keep fresh. A simple mixture of 80-85% ground or cracked corn and 15-20% soybean meal, with free choice high quality alfalfa hay is a very palatable early creep ration. The feed being fed to the ewes may also be included free choice in the creep feeder. Early in the creep feeding period, stimulating intake is of primary concern. These diets should be formulated to contain 20% crude protein.
As the lambs get to 4-6 weeks of age and older, coarser feeds become more palatable. Providing feeds early will enhance the lambs’ acceptance to these coarser feeds. As the lamb gets older, intakes and growth rates should increase. Additionally, the proportion of the gain that is derived from dry feed vs. milk increases. During this time, lambs may be gradually switched to a complete pelleted ration or a ration containing corn and supplement. Over time, the ration should be changed to represent what will be fed once the lamb is weaned. Complete feeds are available commercially, which can be convenient, yet expensive. Pelleted supplements to be mixed with corn are generally cheaper, and are also widely available. At weaning, protein requirements of lambs drop to 15-16%. An advantage of the complete feeds and protein supplements is that they are fortified with antibiotics, vitamins, and minerals which are important for lamb health and performance. Lambs should be vaccinated with Clostridium Perfringens C & D to prevent overeating disease prior to weaning at 6-8 weeks of age.
Table 1. Daily Nutrient Requirements of Mature Ewesa
|Stage of Production||Body Wt. (lb.)||Wt. Diff. (lb.)||DM intake/dayb (lb.)||TDN (lb.)||Protein (lb.)||Ca (g)||P (g)||Vit. A (IU)||Vit. D (IU)||Vit. E (IU)|
|(2 wk. prebreeding &||175||.22||4.2||2.5||.38||5.9||3.6||3760||441||28|
|1st 4 wk. breeding)||200||.22||4.4||2.6||.39||6.1||3.9||4230||505||29|
|1st 15 wk. Gestation||150||.07||3.1||1.7||.29||3.5||2.9||3290||378||21|
|Last 4 wk. Gestation||150||.40||4.0||2.3||.42||6.2||5.6||5950||378||27|
|(130-150% lamb crop)||175||.40||4.2||2.4||.44||6.3||6.1||6800||441||28|
|(180-225% lamb crop)||150||.50||4.2||2.8||.47||7.6||4.5||5950||378||28|
|Lactation (1st 8 wk.)||150||-.06||5.5||3.6||.73||9.3||7.0||5950||378||38|
|a Values adopted from National Research Council for Sheep, 6th Ed.|
|b To convert dry matter to an as-fed basis, divide by percent dry matter.|
Table 2. Daily Nutrient Concentration in the Dry Matter for Mature Ewesa (175 lb. body weight)
|Stage of Production||DM intake/dayb (lb.)||Energy TDN (%)||Protein (%)||Ca (%)||P (%)|
|1st 15 wk. gestation||3.3||55||9.4||.25||.21|
|Last 4 wk. gestation|
|(130-150% lamb crop)||4.2||57||10.5||.33||.32|
|(180-225% lamb crop)||4.4||66||11.1||.41||.25|
|Lactation (1st 8 wk.)|
|a Values adopted from National Research Council for Sheep, 6th Ed.
Values converted from Table 1 by dividing requirement by DM intake.
|b To convert dry matter to an as-fed basis, divide by percent dry matter.|