Published in Scientific Papers. Series D. Animal Science, Vol. LXIV, Issue 1
Written by Vlăduț Dragoș BULMAGA, Ion RĂDUCUȚĂ, Costică CRISTIAN, Ion CĂLIN
The orientation of the breeding and exploitation of sheep for meat production worldwide, imposed a basic technological element, namely obtaining as many lambs as possible, which is the most important goal in increasing this production. The increase of the reproduction indices creates the premise of the profitability of the sheep regardless of the exploitation system practiced. The interest is channeled especially for the increase of fecundity, fertility, and especially prolificacy indices. The intensification of prolificacy is a major objective in the exploitation of all breeds of sheep because it leads to the numerical increase of livestock and meat production. Twin lambs have intense growth energy, which allows the weight of the simple ones to be equalized until the age of the first shearing, and the expenses occasioned by the maintenance of the second lamb are generally reduced. Most of the sheep breeds that are raised in our country are characterized by fairly low values of prolificacy (105-110%), the highest value being recorded in the Merinos de Palas breed. Prolificacy is dependent on genetic factors, especially on the breed. Reproductive characters are characterized, unfortunately, by a low value of the heritability coefficient (h2 = 0.05-0.25), which is determined mainly by non-additive genes, so the selection for this type of characters is very difficult and long-term, the fastest way to improve prolificacy in local sheep breeds is by crossing them with rams from prolific breeds. Internally, within the I.C.D.C.O.C - Palas Constanta, the Prolific Line - Palas was created, following the crossing of Merino de Palas sheep with rams from Romanov, Friesian, and Finnish Landrace breeds, which are characterized by an average prolificacy of 160-180%. Prolific breeds can be used in simple industrial crossings to increase meat production (females prolific breeds x males meat breeds), or to obtain F1 hybrid prolific females in the year I (local breed females x males prolific breeds), which in the second year are crossed with males from specialized meat breeds (double or triple industrial crossings).
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