Monitor body condition score in pregnant ewes during winter months
With lambing season approaching, sheep producers should carefully monitor body condition in their pregnant ewes.
“Nutrition is important because it makes up about 60 percent of the costs per pound associated with producing a lamb,” said Christopher Schauer, North Dakota State University animal scientist. “Nutrition is important because it dictates lactation, reproduction, growth and wool production.”
When ewes are grazing during the winter months, Schauer said producers should check the body condition of the ewes, and score them according to the stage of production they are in. Ewes should also have access to plenty of quality forage, mineral, vitamins and water, and should be supplemented if it is necessary.
To body condition score (BCS) a ewe, producers should first feel for fullness of muscle and fat cover over the loin. Next, they should feel behind the last rib and in front of the hipbone. Last, they should feel for the tips of the transverse process. Schauer said ewes can be ranked anywhere from a BCS of one to five.
• BCS 1 – Emaciated. Spinous processes are sharp, L.E. muscle is shallow with no fat cover.
• BCS 2 – Thin. Spinous processes are sharp, L.E. muscle is full, but little fat cover.
• BCS 3 – Average. Spinous processes are smooth and rounded, L.E. muscle is full with some fat cover.
• BCS 4 – Fat. Spinous processes detectable with pressure, thick fat cover.
• BCS 5 – Obese. Spinous process cannot be detected, L.E. muscle is very full with very thick fat cover.
Schauer said it is important to keep pregnant ewes in BCS range of 2.5 to 3, especially if they have just had their first lamb. Although during late gestation, it is recommended that ewes be BCS 2.5 to 3, by early lactation they should have a BCS of 3 to 3.5. If they are expecting or nursing twins, Schauer recommends 0.5 be added to their ideal BCS.
“If the body condition score for the ewe is not ideal for the stage of production they are in, a producer may need to adjust the ewe’s nutritional requirements,” he said. Old and yearling ewes may need a higher energy ration.
“Energy is the most important requirement in a sheep’s diet,” Schauer said. Although some level of TDN is provided by all feeds whether it is straw, grass, forage or grain, a producer must evaluate their feeding program to ensure the ewe is receiving a balanced ration that meets her energy requirements, he explained.
“Energy is required for efficient reproduction, growth, lactation and wool production,” he added.
Nitrogen or crude protein is also an important part of the diet, he noted. If a producer is considering feeding urea to meet the nitrogen requirements for the ewe, he will need to evaluate the nitrogen content of urea in a percentage or in pounds, Schauer said. Other sources of nitrogen in feed can also be evaluated by determining the percentage or pounds of crude protein.
If the ration is deficient in TDN, nitrogen or crude protein, a number of supplements are available to balance the ration, Schauer said. To evaluate which supplement fits a nutritional program best, Schauer recommended producers compare the cost of different supplements available. Producers should also consider how often the supplement needs to be fed, and if they have the right equipment needed to feed the supplement to prevent waste.
“Producers may need to use bunks and feed the correct amount of the supplement to prevent waste,” Schauer said. “Waste doesn’t add dollars to a producer’s pocket. I would also encourage producers to utilize cheap feedstuffs if they are available.
“Urea supplementation is the most inexpensive source of nitrogen,” Schauer said. However, the animal scientist recommended producers limit it to no more than one percent of the total ration. It also shouldn’t be fed to young lambs or in creep feeds, he added. “Also, ensure that urea is adequately mixed with the rest of the ration to prevent binge feeding.”
If producers supplement their ewes with any type of a cake, block or liquid supplement to meet protein requirements, they need to monitor intake. Schauer said producers may also want to consider alternating days with grain-type supplements.
“Producers can also supplement up to once every six days with high protein supplements,” he added.
To formulate a balanced ration, Schauer encouraged sheep producers to utilize a Montana State University Web site, msusheepration.montana.edu, where they only have to type in the feeds they plan to use, and answer a simple set of questions.