Íslenskar landbúnaðarrannsóknir - 01.09.1981, Page 58

56 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
MATERIAL AND METHODS
Data were collected at Hestur Sheep Ex-
perimental Farm (latitude 64° 34’N,
longitude 21°40’W) frorn September 1977
to October 1979 on testis diameter and
body weight of breeding rams at approx-
imately three-monthly intervals, and on
testis weight of rams slaughtered each
autunrn. The rams were of the native Ice-
landic breed, aged 1—6 years. The numb-
ers of rams or measurements on which the
reported findings were based, are stated in
the respective results sections. The
summer and autumn measurements were
taken during the grazing season whereas
in winter and spring the rams were confin-
ed to housing and indoor feeding of hay
supplemented with concentrates. The
rams were all used for hand-mating on the
farm over a period of 3-—4 weeks in late
December and early January. In both ye-
ars the rams were grouped in pens with
slatted floors in the same building where
large windows guaranteed natural day-
RESULTS
a) Estimation of testes weight
Testes weights of25 adult rams slaughter-
ed in October 1977 and 1979 were corre-
lated with their respective testes diameter
measurements taken before slaughter.
The very highly significant relationship
obtained (r=0.6216; P<0.001; D.F. =23)
indicated that the in situ measurements of
testes diameter gave a useful indirect
estimate of testes weight. On the other
hand, correlations between testes dia-
meter and both age and body weight,
using 65 autumn measurements, were of
light conditions as much as possible. On
the whole the feeding and management of
the rams was according to general farm
practice in Iceland and their healtn was
satisfactory throughout the study. Testis
diameter was measured to the nearest 1.0
mm with a pair of vernier calipers on the
animal in a sitting position, always by the
same operator. The largest diameter was
recorded for each testis, taken approx-
imately mid-way between the caput and
cauda epididymidis with the scrotal skin
included. The testicular parameters
adopted in the statistical analysis were the
pooled values for the left + right testes
diameters of each ram (total testes dia-
meter) and correspondingly, in the case of
testicular weight, the sum of the left + the
right testes and epididymides weight.
Testicular and body weights were recor-
ded to the nearest 0.1 g and 0.5 kg, resp-
ectively.
extremely low values and completely ins-
ignificant. Moreover, a further study of
the data failed to reveal any clear relat-
ionships of that nature indicating that
variation in testes diameter was largely
independent of the age and the body
weiglit of these adult rams.
b) Changes in testes diameter
Seasonal variation in testes diameter was
evident, the pattern being very similar in
both years as shown in TABLE 1, and this
finding was substantiated by the results of