Replacement Ewe Lamb Nutrition

Rearing Systems & Nutrition

Once a flock is established, most producers choose to generate their own replacement females by retaining ewe lambs. In many cases, this puts potential replacement females and market lambs (male and female) into the same rearing system with some probable consequences.

With the recent popularity of all-grain rations for market lambs from weaning (50 days) on, this means potential replacement females are in a feedlot situation before they are identified as meeting the flock standard and are retained as replacements. The major benefit of this system is that all young stock can be raised on a common program, regardless of their future as replacements or for slaughter. That common rearing allows for fewer management groups, fewer rations and more time to identify potential females.

The negative aspects of 'Feedlot Rearing' replacements are threefold:

1. Feeding of grain only at heavier body weights (90 lbs. and over) may result in damage to the rumen. This is on account of acidosis, and would affect the future performance of the organ.
2. Finish is not required on the replacement ewe lamb, as frame development is preferred to achieve timely first breeding. On account of this, grain may be less economical when compared to forages to produce lean growth.
3. Fast growth and unnecessary fat deposition may be permanently detrimental to the mammary development of ewes raised on such programs (Proceedings of the 6th International Great Lakes Dairy Sheep Symposium).

The potential of reduced milking ability of the mature ewe is a direct result of inferior mammary development. Milk production of ewes is a critical factor in lamb performance, especially in prolific breeds. As a result, it may be important to re-evaluate this popular feedlot development of replacement females on account of the potential effects on the animals' subsequent productivity. Alternative rearing strategies of ewe lambs, including feeding diets high in forage are recommended to realize the full genetic potential for milk in commercial and purebred ewes.

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Specific Recommendations

• Sort replacement ewe lambs from market lambs before market weight, and preferably at 60 lbs. of actual weight. Do not remove lambs from creep/grain supplementation or access to very high quality pasture or milk until 60 lbs. body weight (BW) is reached, or growth will suffer due to insufficient rumen development to utilize lower quality feeds.
• Replacement ewe lambs should be grown at no faster that one half of their maximal rate from 2 to 4 months of age (60 to 120 days of age). Assuming feedlot lambs in this age range gain 3/4 to 1 lb. (300 to 450 grams), the growth rate for the replacement ewe lambs should be in the 1/4 to 1/2 lb. per day range (125 to 250 grams), targeting for 1/3 lb./day. This can typically be achieved with good forage and no more than 1 lb. of grain per head per day.
• Frame growth can be achieved from 120 days to breeding, targeting for a minimum of 60% of mature body weight at breeding, with 70% being preferred especially where no slippage due to open ewe lambs is acceptable (e.g., annual grass lambing). For example, for a Rideau ewe lamb entering an accelerated production system, the breeding weight should be 90 to 110 lbs., assuming a mature body weight of 150 to 180 lbs. This animal reaches the 60% minimum, but the slippage might be tolerated due to the accelerated program where she may be re-exposed in a few weeks.
• Ewe lambs at 12 months should have a minimum target bodyweight of 75% of mature bodyweight. Using the same example of a 150 to 180 lbs. mature ewe, this is 125 to 135 lbs. shortly post-lambing.
• These management benchmarks require actual in-flock mature ewe weights! These should be taken on 3 to 4 year-old ewes, and not by 'guess'! The actual weight of a ewe might be surprising; more importantly it has management and feeding implications.
  

Sample Rations for Ewe Lambs

The following ration suggestions for ewe lambs from flushing onward are for guidance only, and should not replace the recommendations from your feed provider or flock nutritionist. A number of assumptions have been made to allow the formulation of the following rations. These include:

• Corn is the energy source standard. Where that is not the case, the amount of corn may be altered to meet wheat, barley or mixed grain feeding systems. For each feed used in practice use the following coefficients to adjust the grain amount given in the following tables.
  • Where wheat is used - reduce grain by 10% of corn amount
• Where barley is used - increase grain by 10% of corn amount
• Where mixed grain is used - increase grain by 15% of corn amount

For example, if the table calls for 0.5 lbs. Of corn to be fed per head/day, and barley is in fact used, then the amount of barley is (0.5 + (0.5 x 0.10) = 0.55 lbs. per head/day.

• A generic supplement in the range of 30 to 35% crude protein (CP) was assumed. Similar to the correction possible for grains, a CP correction can be made to reflect protein sources such as soybean meal, or other pelleted supplements higher or lower than 30 to 35% CP.
• It is assumed that mineral is provided in the supplement where one is used, or as free choice loose mineral. Regardless of what supplement is used, ensure that its usage rate (pounds per head per day) provides sufficient mineral, or that free choice mineral is consumed at the recommended rate
• Forage CP represents forage maturity and thus energy in this grass/legume hay. In reality however, legume to grass ratio can affect CP content more dramatically than maturity. Less mature (higher CP) forage is generally more digestible, higher in energy and more desirable.
• NR - indicates the forage is not recommended for that stage of production, either because it is too low or excessive in nutrients.
• Forage quality should be determined by forage analysis on an annual basis.
• The range in supplementation recommendations for pasture is a reflection of variable management and seasonal effects.

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Typical Ewe Lamb Rations

110 lb. Ewe Lambs - Body Condition Score 3
Formulated on a forage, corn and supplement basis

Typical Ewe Lamb Rations

130 lb. Ewe Lambs - Body Condition Score 3
Formulated on a forage, corn and supplement basis

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