Dairy Sheep Symposium - the Department of Animal Sciences ...

Breed Usage in Europe
Crossbreeding or substitution with high-yielding breeds has also considerably been used in
some European countries, especially in Spain. In a recent study (Ugarte et al., 2001) it has been
estimated that 45% of Spanish dairy sheep are affected by crossbreeding and that Assaf, Awassi,
Lacaune and East-Friesian have 800,000, 150,000, 75,000 and 10,000 head respectively as pure
breeds or with a high percentage of blood. These breeds have been introduced when farmers wished
to increase the genetic level of their populations because they are able to improve or intensify the
management of the animals and are not willing to wait until local breeds reach the desired level
through selection. Available results on the use of these high-performance breeds indicate that around
1.5 l/day can be obtained in F1 crosses and 2 l in pure-breds, which means an increase of 50% and
100%, respectively, in relation to the production of the local breeds. Nevertheless these high yielding
genotypes generally need a more careful management that may increase costs and limit their use in
extensive or semi-intensive systems. Furthermore, they could be environmentally negative due to
the non-use of natural resources of marginal areas, well exploited by the local breeds, and to the
genetic contamination of local and well adapted local breeds.
In Italy, the results of the use of the crossbreeding between the East Friesian and the native
Sarda (Sa) breed have recently been reported by Sanna et al. (2001). Descendants of those crosses,
having on average about 50% of East Friesian genes, were classified as belonging to a “syntethic”
breed (FS). From 1978 to 1992 more than 5,000 FS and Sa lactations were recorded on an experimental
farm. The comparison between the native and the “synthetic” genotypes was made on
liveweight, reproduction performances, lamb production and milk, fat and protein yields. FS resulted
heavier than Sa (52 vs 44 kg liveweight) and showed higher prolificacy and higher lamb
production. Milk yield resulted only slightly different between genotypes: 193.7 vs 187.7 for FS
and Sa ewes, respectively. Nevertheless, due to lower liveweight and related feed requirements for
maintenance, Sa ewes resulted more profitable than FS in terms of gross income per metabolic
weight (9.53 vs 8.66 Euro per kg, respectively).
In Turkey, Gursoy et al. (2001) report the results of milk production and growth performance of
a Turkish Awassi flock when outcrossed with Israeli Improved Awassi rams. The offspring of the
highly selected Israeli Improved Awassi genotypes were found to give higher performance of 5%
(lamb growth) and 20% (milk) than local sheep.
Selection Criteria other than Milk Yield
Milk Composition
The main use of ewe´s milk is its transformation into cheese since its composition is fairly well
adapted to the required processes. As a consequence cheese yield is a parameter of high economical
importance for cheese manufacturers. At the present moment milk recording schemes include
estimations of milk parameters such as fat, protein, total solids and somatic cell count (SCC), but
there is no automated method available to obtain individual cheese yield estimations. In this regard
an investigation has been performed in the selection nucleus of Spanish Churra sheep aiming at
developing indirect methods to estimate cheese yield (Othmane et al., 1995; 2000) although its
application in practice is not economically interesting for the moment. A variable named “individual
laboratory cheese yield” (Othmane, 2000) and presumably closer to industrial cheese yield than
milk composition variables was proposed.
Descriptive statistics of the population for different milk traits (Table 4) show a high variation
as expected for semi-extensive ovine farms under a high environmental component and at a
first step of a selection program.