Although early weaning of lambs is controversial, Dr. Woody Lane, PhD, says in the publication The Shepherd that there are some benefits.

Dr. Lane believes early weaning can help with good pasture management and parasite control. Weaning creates two different flocks: dry ewes and weaned lambs with wildly different nutritional needs. Dry ewes need only maintenance levels of nutrition, while weaned lambs need high levels of protein and energy. 

Keeping all these animals together will cause some to be overfed and some to be underfed. The dry ewes can be on a poor-quality pasture or fed poor-quality hay. Fast-growing lambs, on the other hand, need high-quality feed.

Lambs born in the winter or early spring have well-developed rumens by the time spring pastures are ready for grazing and will do well on this good quality forage. If the herd is together, the ewes will eat some of the good quality forage, which should all go to growth in the lambs, so early weaning allows you to let the lambs get the good quality grass, and you will have to purchase less grain. Early weaning really makes sense when pastures begin to mature and forage is limited.

Dr. Lane believes the second benefit of early weaning is parasite control. Sheep on green pastures usually become infested with intestinal parasites, and adult ewes usually have some resistance to fight off the parasites.

However, lambs lack this ability due to their decreased immune system, and parasites cause a major decrease in growth and can be deadly. These lambs need to be checked closely by checking their FAMACHA score, and frequent deworming will be required, whereas the dry ewes are not as susceptible to these parasites, and there are also fewer parasites on the poor-quality pastures.

Discuss your questions about weaning programs and parasite control with your veterinarian.