Agriculture Reference
In-Depth Information
out at the Meat Research Institute, Bristol, and in New
Zealand has shown that carcases from entire ram lambs
grade about one fat class lower than those from ewes at
the same weight without deterioration in eating quality.
The entire ram lambs had lower values of subcutaneous
and intramuscular fat, and a higher proportion of the
total fat in the rams was deposited subcutaneously where
it can be removed by trimming - an important commer-
cial consideration. Some 30% of the New Zealand kill is
now composed of entire ram lambs, non-castration
being encouraged.
Research work on carcase and meat composition and
tenderness of meat from ram, wether and ewe Dorset
Down-cross and Suffolk-cross lambs slaughtered at 20
weeks of age showed that differences in meat quality
were very small, tenderness of ram meat being ensured
by efficient refrigeration control. The fact that the rams,
especially the Suffolk crosses, grew faster, yielded larger
joints and had good carcase conformation in addition to
meat tenderness would indicate potential for ram lamb
production in the United Kingdom (Dransfield
et al
.,
1990). When the adverse aspects of castration - namely,
sepsis, which often leads to pyaemia and sometimes
death - the improvement in welfare and labour and
equipment costs are considered, the lead given by New
Zealand would seem a good one to follow.
The desirable features required by the butcher in both
lamb and mutton carcases of any breed are short stocky
plump legs, thick full loin, broad full back, thick fleshy
ribs with a wide breast and shoulder, a good depth of
chest cavity, a short plump neck and overall lean content
(Fig. 1.8, Fig. 1.9 and Fig. 1.10).
increase fecundity, mothering ability and carcase quality.
More recently, French Texels, Beltex, Berrichon du Cher,
Rouge de l'Ouest and Charolais have been imported for
crossing purposes. The Cambridge breed of sheep is
another recently developed breed which is very prolific.
British breeds of sheep are not found extensively in
Europe, although Cheviots and some lowland types occur
in Scandinavia, but many have found their way to other
parts of the world. In Australia, about 75% of the 126 mil-
lion sheep are Merinos, the remainder being crosses with
certain British breeds. In New Zealand, the Romney
Marsh predominates, followed by Corriedales, Merinos
and Southdowns and their crosses. In the United States,
the Rambouillet is the main representative of the Merino,
and a lot of cross-breeding occurs, with larger sheep units
under confined systems of management becoming more
important. However, it is doubtful whether sheep grazing
in the United States will expand very much. In South
Africa and the USSR, the most important breed is the
Merino. Fat-tailed and fat-rumped sheep are found in the
Middle and Far East; the Awassi breed is an important
coarse wool type in the eastern Mediterranean and Iraq,
where the wool is used mainly for making carpets.
In some parts of Europe, milk or dairy sheep are of
significance: the common breeds are East Friesland
(Holland), Cochurro, Lancha and Mancha (Portugal and
Spain).
In recent years, more attention is being given to the
production of fine wools, cashmere and mohair which
the textile industry needs and presently has to import. In
addition to sheep, Angora goats and rabbits, alpacas and
llamas also produce quality fibres. Judicious crossing of
British sheep with Merinos, for example, Merino de
l'Ouest from France, produces sheep capable of high
lambing percentages, good growth rates and carcase
quality as well as fine fleeces.
In addition to better feeding methods, improvements
in sheep production are currently centred on the use of
hormones to increase the number of lambs born and
out-of-season lambing, hybridisation to produce a supe-
rior stock of leaner types, oestrous synchronisation, early
weaning and artificial rearing of lambs. Intensification
on grass and fodder is possible as long as farmers are
aware of the problems involved.
In the United Kingdom, the demand for young and
small carcases means that lamb is the more important
product. Lambs are usually slaughtered at between 36
and 50 kg live weight giving a dressed carcase of 17-23 kg.
'Mutton' is derived from lambs not attaining a finished
condition before weaning and from ewes, wethers, hog-
gets and rams.
As in the case of cattle and pigs, use has been made of
entire ram lambs to produce leaner carcases. Work carried
Definitions
Lamb
A sheep from birth to weaning time (generally at 3½-4½
months old). Butchers apply a more generous interpreta-
tion to the term 'lamb' and use it to denote a sheep from
birth until shearing time the following year; by this inter-
pretation, a sheep 13 months old is still classed as lamb.
Hogget
A 'lamb' in its second year, often with two permanent
incisors replacing the lamb teeth.
Tup or ram
The uncastrated male.
Wether
The castrated male sheep (usually castrated before 1 week
of age with a rubber ring or at 3 weeks to 3 months old
by other methods).
