The Far Side: Mating Rituals 2006 Wall Calendar by Gary.

Breeding efficiency is a major component in the overall efficiency of sheep production. Usually the best basis for any type of sheep production is the native (indigenous) animal. Under poor extensive conditions long term breeding efficiency is achieved at a lower reproduction rate; prolificacy is not desirable. However, under intensive conditions breeding efficiency (prolificacy, frequency of lambing and weaning percentage) should be increased. The genetics of the native breeds may be improved by selection or crossbreeding with other breeds characterized by higher prolificacy and longer breeding season.

Practical methods of selection include selection of ewe lamb replacements born as twins or born as singles from younger ewes and producing higher milk yields than the average milk yield of the flock and the selection of twin born rams or rams from ewes with a high level of twinning throughout their lifetime and which have a higher post weaning growth rate than the average post weaning growth rate of the ram lambs in the flock.

The desirable traits in a crossbreeding system in additon to improving breeding efficiency are higher milk yield, improved growth rate, feed efficiency and market desirability of lambs and better adaptability of ewes and lambs to the environmental conditions. To avoid inbreeding; mating is confined to individuals that have no common ancestor nearer than one great grand-parent.

All ewes in poor condition, dry ewes which were not pregnant after the mating period, ewes with low maternal instinct, non-functional udders or with extremely large teats, or suffering from chronic diseases, should be culled. Ewe lambs that fail to breed in the same breeding season with other ewe lambs should also be culled. Rams with limited fertility and sex drive, suffering from lameness or any chronic respiratory disease should be replaced with young rams.

Early breeding of female lambs is an important method of intensifying sheep production in the self-replacing flock because it can increase the annual flock output, reduce the unproductive phase and thus overhead costs, facilitate selection programmes and also increase total lifetime productivity. Early breeding of well managed and adequately nourished ewe lambs has no detrimental effects on their subsequent performance and reproductive efficiency.

The important principle to bear in mind is to keep the lambs growing and gaining weight after weaning so that by breeding time they will be sufficiently mature physically to mate successfully. First oestrus is affected by age and body weight which in turn are influenced by the breed and nutrition. Female lambs are kept separately from ewes until lambing. Excessive feeding in late pregnancy should be avoided in order to reduce the incidence of dystocia. During the last two months of pregnancy the level of energy intake should be between that of a mature ewe carrying a single lamb and one carrying twin lambs.