Dr. Andrew Weaver, North Carolina State University, Small Ruminant Specialist
Ewes 
are bred, the holidays are just around the corner, and for all of us with winter lambing flocks, lambing season is almost here. Over the last year, we have invested in high quality genetics to move our flocks forward and now it’s important that we make sure our next generation of lambs get off to the right start. This begins with good late gestation management.
I have summarized nutritional requirements in Table 1 (think of this as nutrient demand by the animal). Requirements for energy (as indicated by total digestible nutrients) and protein increase substantially for late gestation and lactation compared to maintenance. Two-thirds of fetal development take place during late gestation. Additionally, ewes should be gaining body condition to prepare for lactation with a goal of BCS 3.5-4 at the time of lambing. Therefore, nutrients demands are high.
| Table 1. Nutrient Requirements (Demand) at Different Stages of Production | |||
| 150 lb. ewe raising twins | Dry Matter Intake (lb./d) | Total Digestible Nutrients (lb./d) | Crude Protein (lb./d) |
| Maintenance | 2.6 | 1.4 | 0.2 |
| Late Gestation | 4.0 | 2.7 | 0.4 |
| Lactation | 4.4 | 2.9 | 0.7 |
If these demands are not met, several disease challenges could arise. Pregnancy Toxemia results from insufficient nutrient intake and negative energy balance during gestation or lactation. Young ewes carrying multiples are most susceptible. Milk fever is less common but can occur when ewes are feed restricted, have insufficient calcium intake, transported long distances, or have excessive movement in late gestation. Both Pregnancy Toxemia and Milk Fever result in down ewes and eventual death if not treated.
If ewes do not have sufficient energy stores at the start of lactation, they may become extremely thin by the end of lactation or milk production could be compromised. Further, undernutrition during late gestation may result in low birthweight lambs. Low birthweight lambs are more susceptible to developing Starvation/Hypothermia Complex, a leading cause of death in lambs under a week of age. Survival of lambs born at less than 5 lb. may be less than 50% (Maund et al.).
On a strictly grass hay diet, expected energy and protein intake have been calculated in Table 2 (think of this as nutrient supply for the animal). These values should be compared to the requirements (demand) in Table 1. When supply is less than demand, supplemental nutrition is needed. Forage quality is going to vary greatly so get your hay tested, know the nutritive value of pasture forages, and adjust supplemental feeding accordingly.
| Table 2. Expected Nutrient Intake (Supply) at Different Stages of Production | |||
| 150 lb. ewe raising twins | Dry Matter Intake (lb./d) | Total Digestible Nutrients (lb./d) | Crude Protein (lb./d) |
| Maintenance | 2.6 | 1.4 | 0.3 |
| Late Gestation | 4.0 | 2.2 | 0.4 |
| Lactation | 4.4 | 2.4 | 0.5 |
| Assumes grass hay is 88% DM, 54% TDN, and 11% CP | |||
To avoid disease challenges, mark a date 30-45 days prior to the start of lambing. On that date, vaccinate your ewes for Clostridium perfringens types C&D and tetanus, trim feet if necessary, check FAMACHA and body condition score, and adjust rations to ensure late gestation nutrient requirements are met. This may require adding in some supplemental concentrate feeds to the diet. Then, let your ewes relax and avoid handling to minimize stress until they lamb.
Hope everyone has a great holiday season and a successful start to lambing.