Rit Landbúnaðardeildar : B-flokkur - 01.09.1961, Blaðsíða 110

108
The following figures show the average difference per lamb in favour of those on aftermath
in weight of dressed carcass and offal in each experiment.
Expt. Length Dressed Caul Pelt Total
No. of expt. carcass fat kg products
days kg kg kg
III 27 1.03 0.45 0.17 1.65
IV 28 0.78 0.07 0.20 1.05
V 23 0.14 —0.01 —0.02 0.11
VII 24 1.16 0.21 0.29 1.66
Mean 25.5 0.78 0.18 0.16 1.12
b: Xn the 11 experiments No. I, II, VI and VIII to XV where a control group was killed at
the beginning of each experiment and by presuming that at that stage all grotips in the same
experiment werc equally well developed, the average actual gain per lamb in weight of
dressed carcass and offal in each group in all the experiments was calculated. The following
figures give the average gain in dressed carcass weight, grammes per day, for each treatment
in these experiments (see page 109).
1. Unweaned lambs on the hill gained on the average 37.7 g per day in dressed carcass iti
these 11 experiments or equivalent to 1.13 kilos per month. The great difference in gain in
the various experiments appears to be partly due to years, quality of hill pasture, and on
how late in October the experiments were terminated.
Weaned lambs gained on the average in dressed carcass weight as follows:
In eight experiments on marrowstem kale 83.7 g per day or equivalent to 2.51 kilos per
month. In two of these experiments No. X and XIII insufficient marrowstem kale was avail-
able. By omitting the results of these two experiments the average daily gain in the re-
maining six experiments was 96.0 g or equivalent to 2.88 kilos per month.
In three experiments on young grass the weight gains were 60.2 g per day or equivalent
to 1.81 kilos per rnonth.
In two experiments on aftermath the gains were 54.4 g per day or equivalent to 1.63 kilos
per month.
In one experiment on green oats and winter-rye the gains were 117.9 g per day or equi-
valent to 3.54 kilos per month.
In one experiment on rape, turnips, and young grass the gains were 78.8 g per day or equi-
valent to 2.36 kilos per month.
In two experiments on marrowstem kale, where the lambs received 3 mg stilbestrol sub-
cutaneously at the beginning of the experiment the lambs gained 65.2 g per day while lambs
on marrowstem kale in the same experiments which were not treated with stilbestrol gained
65.9 g per day indicating no effect of this srnall dose of stilbestrol.
2. In these experiments the rate of growth of the lambs was much affected by years, length
of the experimental period, and whether the experiments started early or late in autumn. Due
to this, comparison in rate of gain in grammes per day between treatments as described
under paragraph 1 above does not give a true picture. To get an unbiased comparison between
the different treatments one must compare the rate of gain in different treatment groups
in tlie same experimenl in different years. On hill pasture the lambs had the highest rate of
gain in experiments No. I and II, but in these experiments there was no comparison with
Jambs on marrowstem kale.
In experiment No. IX and XII Iambs on hill pasture also had high rate of gain per day
and in these experiments the lambs on marrowstem kale, young grass and oats, and winter-