Ewes can be made to give birth in fall, winter, or spring months, either by artificial insemination or by facilitating natural mating.[5] Fall lambing is generally not done as the lamb crop percentage is likely to be low; ewes often need hormone therapy to induce estrus and ovulation, and farm labor is often busy elsewhere during fall lambing. Furthermore, fall-born lambs can be weak and small bec
ause of heat stress during the summer gestation period. Spring lambing has the advantage of coinciding with the natural breeding and lambing seasons, but supplemental feed is often needed. The advantage of winter lambing is that the lambs are weaned in spring when pastures are most fertile. This allows the lambs to grow more quickly, and to be sold for slaughter during the summer (when prices are generally high), but it results in roughly one in every four newborn lambs dying within a few days of birth due to malnutrition, disease, or exposure to the harsh cold. In the UK, it results in around 4 million newborn lamb deaths.[6] 'Accelerated lambing' is the practice of lambing more than once a year, typically every 6 to 8 months. The advantages of accelerated lambing include increased lamb production, having lambs available for slaughter at different seasons, year-round use of labor and facilities, and increased income per ewe. It requires intensive management, early weaning, exogenous hormones, and artificial impregnation. It is often used to make old or soon-to-be infertile ewes give birth one more time before they are slaughtered.[5]
Lamb marking
Main article: Lamb marking
After lambs are several weeks old, lamb marking is carried out.[7] This involves ear tagging, docking, mulesing, and castrating. Ear tags with numbers are attached, or ear marks are applied, for ease of later identification of sheep. Tail docking is commonly done for welfare, having been shown to reduce risk of flystrike when compared to the alternative of letting sheep collect waste around their buttocks.[8] The Merino breed, accounting for around 80% of the wool produced in Australia, have been selectively bred to have wrinkled skin resulting in excessive amounts of wool while making them much more prone to flystrike.[9][10][11] To reduce the risk of flystrike caused by soiling for the lambs who make it to summer, Merino lambs are often mulesed at the same time, which involves cutting off the skin around their buttocks and the base of their tail with metal shears. If the lambs are younger than 6 months, it is legal to do this in Australia without any pain relief.[12] Male lambs are typically castrated. Castration is performed on ram lambs not intended for breeding, although some shepherds choose to omit this for ethical, economic or practical reasons.[7] A common castration technique is 'elastration,' which involves a thick rubber band being placed around the base of the infant's sc***um, obstructing the blood supply and causing atrophy. This method causes severe pain to the lambs who are provided no pain relief during the process.[13] Elastration is also commonly used for docking. Though no laws mandate this practice, depending on the preference of the shepherd, docking and castration are commonly done after 24 hours (to avoid interference with maternal bonding and consumption of colostrum) and are often done not later than one week after birth to minimize pain, stress, recovery time, and complications.[14][15] Ram lambs that will either be slaughtered or separated from ewes before sexual maturity are not usually castrated.[16] Objections to all these procedures have been raised by animal rights groups, but farmers defend them by saying they save money, and inflict only temporary pain.[
