Graduate Thesis Or Dissertation
 

Biological and economic effects of flushing and creep feeding in sheep

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  • 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 experimental period. 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 in liveweight. 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 systems.
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