Ársrit Ræktunarfélags Norðurlands - 01.01.1980, Síða 21

The level of production is mainly decided by the following three
characters:
1. Fertility of ewes, defined as number of lambs weaned per breeding
ewe.
2. Carcass weight of lamb and mutton.
3. Number of lambs weaned from one year old ewes.
fn addition, the production efficiency is also affected by the ewe weight,
but that character will not be taken into consideration here.
The feed used can be devited into three groups:
Feed for growth of the foctus and the lamb.
Feed for growth of replacement in the flock.
Feed for maintenance.
These three main items are dealt with separately.
On average the resuts are as follows.
Feed for maintenance 218,0 FE p.a.
Feed for replacement in the flock 32,3 FE p.a.
Feed for growth and maintenance of lamb; twin 13,5 kg carc.wt. 111,1
FE; single 16,4 kg carc.wt. 127,4 FE.
The feed for maintenance is calculated as 0,6 FE per day. For replacement
there is found need for 194 FE for each animal, and as the average age is
found to be 6 years, this gives 32,4 FE per a. The need for growth and
maintenance of the lamb is calculated by norms from Breirem (1961), and
the average age of lambs at slaughter in Iceland is 135 days.
As an example, it will cost 23.09 FE to produce one kg of lamb meat when
the level of production is 16,4 kg per head and 17,54 FE when the
production is 27,0 kg per head.
It is pointed out that the most efficent way to increase the production per
head is to increase the fertility.
It is shown that when the production is 13,5 and 27,0 kg per head, as an
example, the production per ha of average range land in Iceland is 42%
higher at the higher level of production.
It is also pointed out that by producing the same amount of meat it will
cost much less feed per kg measured in FE, when the level of production is
high and will in addition give a lower stocking rate, and hence, under
Icelandic condition, faster growth of lamb and better condition of ewe.
Taking as an example, when weaning 1,78 lambs per head with 13,5 kg
carcass weight, which is considered as a high level of production in Iceland,
compared with 0,83 lambs weaned per head, with 16,0 kg carcars weight,
which also is found in Iceland, on the higher level of production, there 55,3
sheep would be needed compared with 100 sheep needed at the lower level
of production to produce the same amount of meat. At the lower level there
would be needed 35.256 FE to produce 1.328 kg meat compared with
24.822 FE at the high level.
23