Consequently, I find industry benchmarks to be a useful tool in evaluating our progress as sheep producers. The U.S. Lamb Resource Center has recently developed benchmarks and best practices related to reproductive efficiency (click here for "Best Practices for Increasing Your Lamb Crop"). The benchmarks establish standards for reproductive efficiency for high and low input range flocks as well as for high and low input farm flocks. According to the Center, high input flocks use shed lambing, herders, multiple management groups, strategic feed supplementation, and improved pastures. Low input flocks use range/pasture lambing, fenced pastures, simple management groups and limited supplementation.
First, a note on how we manage our sheep. From a size standpoint, we would be considered a farm flock - but from a management perspective, we operate like a range flock. We lamb on pasture, and we focus on grazing rather than supplemental feeding to meet the flock's nutritional needs. I suppose we fall somewhere between high and low input. Here's how we compare to the industry benchmarks:
Key Reproductive Indicators
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Range Flocks
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Farm Flocks
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Flying Mule Farm
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High Input
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Low Input
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High Input
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Low Input
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2016
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Dry Ewes
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<7%
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<10%
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<5%
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<7%
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3.50%
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Lambs Born
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150%
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120%
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200%
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175%
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181.10%
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Lamb Losses
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15%
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17%
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11%
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15%
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6.00%
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Lambs Weaned
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127%
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100%
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178%
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148%
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164.90%
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Ewe Lambs Lambing
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50%
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30%
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85%
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65%
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0%
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Looking at these numbers a bit more closely, our conception and lambing rates (reflected in the numbers for "dry ewes" and "lambs born") exceed the benchmarks for range flocks. Only 3.5% of our ewes didn't get bred in 2015, and our lambing percentage was more than 181%. From late gestation through weaning, we had a total lamb death loss of 6%, and we weaned a 165% lamb crop. The only category where we didn't meet the industry benchmark was in breeding our ewe lambs - we wait to breed our ewe lambs until they are 18 months of age - when they are no longer considered to be lambs (more on this below).
The Lamb Resource Center suggests selecting from 12 Lamb Crop Best Practices to improve reproductive efficiency. The Center stresses that these practices don't fit every operation; rather, producers should pick those that have the the greatest impact. Below, I've described the practices that fit our operation, as well as those that we'd like to implement.
- Optimal Nutrition. Ewes should be on a rising plane of nutrition prior to breeding and have a body condition score (BCS) of 3 or slightly less at breeding. We made significant strides in this area last year, and plan to duplicate our effort this year. Beginning this weekend, we'll start supplementing our irrigated pasture with canola meal (which is high in protein and energy). Our lambing schedule is timed to match the ewes highest nutritional needs (during late gestation and early lactation) with the onset of rapid grass growth in the spring.
- Breed Ewe Lambs at 7-9 Months of Age. We don't (and probably won't) follow this guideline. We want our ewe lambs to weigh approximately 85% of their mature weight at breeding. Our forage resources make this difficult to accomplish at 9 months of age, and we're not convinced that supplemental feed is worth the extra expense. In our pasture lambing system, waiting to breed the ewe lambs until they are 18 months old has the added benefit of reducing many of the lambing problems common to smaller ewe lambs, like dystocia and mis-mothering.
- Select for Prolific Genetics. One of the silver linings of our ongoing drought has been the fact that we have retained only those ewes who had given birth to twins in the past. This year, the only replacement ewe lambs we kept were from multiple births. We've always purchased rams that were from multiple births. Given the importance of genetics to prolificacy, we'll continue to follow this practice.
- Use Crossbreeding. First-cross lambs have a 5% higher survival rate than straight-bred lambs, and first-cross ewes tend to have higher lamb crops than purebred sheep. We use mule ewes (which in our case are a cross between the Cheviot and Blueface Leicester breeds) as our primary breeding flock. We cross these ewes with Shropshire rams, giving us additional heterosis. This combination seems to work well in our environment, both in terms of lamb crop and lamb performance.
- Cull Underperforming Ewes. We cull ewes that don't measure up in our EZ-Care record keeping system (which evaluates ewes on lambing ease, mothering ability and lamb vigor). We also cull for missing teeth and for udder problems (hard bags or misshapen teats). I think this is part of our success in terms of maternal ability and conception rate.
- Reduce Lamb Loss. Postnatal lamb losses should be below 10% of all lambs born. Our vaccination program, nutritional program, and predator prevention system seems to be working. And the maternal ability of our ewes doesn't hurt, either!
- Test for Pregnancy Status. We have used ultrasound in the past to determine pregnancy status. For us, this is a drought management strategy - we can sell any ewes that aren't bred if we're worried about a lack of forage. High input producers take the additional step of separating ewes with single lambs from those carrying multiple lambs (so that the multiple-bearing ewes can get extra nutrition). We don't have the ability to manage separate groups like this, so we probably won't incorporate preg-testing as a normal practice.
- Disease Prevention and Treatment. I'm fortunate to be married to our vet! We do a pretty good job of preventing most common diseases and treating them when they arise. We also use the California Animal Health and Food Safety Lab at UC Davis to help evaluate health issues.
- Match Reproduction to Management. I feel like this is one of the most important practices on the entire list. We raise small to moderate sized sheep - which means they don't need as much forage to maintain condition as larger sheep. Over the years, we've paid attention to the ewes that remain productive in our environment - and we've sold those that didn't.
- Test Rams. The center suggests using a general breeding soundness exam on rams 30-60 day prior to breeding. We haven't done this in the past, but it's probably worth considering.
- Manage for Seasonal Changes in Reproduction. The breeds we use were developed in England, and like most English breeds, they are seasonal breeders. Their ovulation rates peak in October and November (which means their lambs will be born in February and March). While some producers may try to manipulate their ewes' estrus cycles, we feel like the seasonal nature of our ewes' fertility matches our feed resources (which peak in April).
- Accelerate Lambing Cycles. Some high input producers try to get 3 lamb crops every 2 years (ewes are pregnant for 5 months, making this acceleration possible). In our range-based system, this won't work for us.
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