|Abstract or Summary
- One hundred two mature blackface crossbred ewes were randomly
divided into three equal groups to examine the effects of feeding
management during mating on blood chemistry, weight change and
subsequent reproductive performance.
Group I was kept in drylot from 17 days before through 17 days
after the start of mating. At that time, they were returned to
pasture. Group II was treated similarly, but ewes were put on
pasture immediately after they were mated by a ram (assessed daily
by raddle marks). Group I and II were fed 1.1 pound alfalfa hay
and .5 pound barley per head per day plus grass-clover hay ad libitum.
Group III spent the entire flushing and breeding season on improved
dryland hill pasture. Bodyweight was recorded on all ewes and blood
samples were collected on 20 ewes per group at two week intervals.
At lambing, ewes were randomly divided within feeding treatment
groups to creep and non-creep feeding. Twenty-five creep and 26
non-creep lambs were bled far chemical. analysis at weaning. Feeding method during mating did not significantly affect weight
change. However, there was significant variation in ewe weight with
time. The analysis of variance of effects of various factors on ewe
blood parameters showed highly significant (P<.005) differences among
sheep and a highly significant treatment x time interaction. Blood
chemistry levels did not follow the weight change pattern over the
There were significant individual differences among sheep for
blood protein, albumin, blood urea nitrogen (BUN) and weight (P<.005).
Repeatability, however, was only 0.08, 0.10 and 0.11 for blood protein,
albumin and BUN, respectively. Repeatability for weight was 0.71.
Nutritional treatments did not affect blood chemistry levels.
An analysis of variance was completed to test the effects of
nutritional treatment, weight and weight change on number of lambs
born. Neither treatment nor weight change effects were significant.
However, liveweight was positively related to twinning rate (P<.05).
The regression coefficient was .007 lambs born per pound increase
The effects of feeding treatment and the treatment x creep
interaction on total weight of lamb weaned per ewe lambing were
not significant; however, ewes whose lambs had access to creep
weaned 18 pounds more lamb than the non-creep group (P<.05).
Lamb blood chemistry did not affect weaning weight significantly,
but the -creep fed group had higher BUN (17.9 vs. 15.7 mg/100ml) and
total weaning weight (104 vs. 95.9 pounds) (P<.01). At weaning,
there were six lambs ready for slaughter in the creep group as compared to one in the non-creep group of lambs. Creep feeding did
not influence subsequent post weaning weight gain.
Based on current lamb:feed price relationships and return per
nutritional treatment, flushing in drylot and creep feeding, even
though the latter resulted in more pounds of lambs weaned, are
not viable investments in commercial western Oregon sheep production