The crossing and production of lamb : Adipose tissue development

The crossing and production of lamb :
Comparison and selection of male breeds
J.
)
*
(
C. FLAMANT
Station !’!M:e7:o!a/to!
génétique
G. PERRET
des animaux. Centre de Recherches de Toulouse,
I.N.R.A., B.P. 12
, 31320 Castanet Tolosan.
00 Toulouse.
5
I
3
, bd de la Gare,
)
*
(
* I.T.O.V.I.C., 3¢
First
through
generation crossbreeding experiments
the collaboration of the
for lamb
production
realized
were
nrESr.
D
LN.R.A., the LT.O.V.f.C. and the bh
6
during 197
They clearly
confirm differences in the growth rate and conformation of sire breeds, criteria which can be
observed on live animals. But carcass measurements indicate large differences in tissue composition (especially total fat) and in the distribution of adipose tissue. Texel sires give leaner carcasses at same weight, and Berrichon cross lambs are the fattest with the largest dorsal fatdeposits.
Lacaune have the greatest proportion of bone, but adipose tissue is mostly internal with little
dorsal fat.
Several questions remain to be studied:
-
and the
-
Can
genotypes always be classed in the
type of lamb desired?
What is the
possibility
of
selecting
same
way, whatever the
for restricted
carcass
breeding system
used
fatness; is this selection in oppo-
sition with conformation and maternal abilities?
For the breeders,
where each breed
we
can
advocate the creation of
be
given
a single progeny test station for several breeds,
the best orientation for its selection.
Adipose tissue
effect of type of fat
development
incorporated
B. AUROUSSEAU
in meat lambs :
into the milk replacer
M. THERIEZ
Laboratoire d’Étude dxa Métabolisme énergétique.
Station de Recherches sur l’Élevage des Ruminants.
Centre de Recherches de Clermont-Ferrani. l, I.N.R.fI.,
Theix, 6
rio Beaurnont (France).
3
A first trial involving 12 Charmois lambs demonstrated the significant effect of tricaprylin
mgestion before weaning on adipose tissue composition at weaning (gg days) and at slaughter
8 kg). Saturated fatty acid content of the back fat thus decreased at weaning from
120 days, 2
(
3 %! and the content of unsaturated fatty acid increased from 3
.
8. to 44
2 %. At
.
8. to 33
3
9
slaughter the saturated fatty acid content of the back fat at the same site decreased from 3!.8 to
.6 %, while the unsaturated fatty acid content increased from 50.! to !z.9 % ; odd andbranch31
6.o %. Again, at slaughter saturated fatty
ed-chain fatty acid content increased from m.6 to 1
acid content of the inner back-fat decreased from j6.
2 to 50
2 °/" and unsaturated fatty acid
.
content increased from 3
8. to 44
.2 °4!!
In a second trial involving 59 Limousin or Limousin x Romanov lambs, slaughtered at
31 lambs), direct and long-term effect of tricaprylin
weaning (z8 lambs) or at 35 kg of weight (