Abstract :
Twenty-four Boer crossbred yearling wethers (23.5±2.31 kg initialBW)were used to determine effects of stepwise increases
in dietary level of Eastern red cedar (Juniperus virginiana) foliage (CF), compared with a constant relatively high level and
subsequent availability of low-quality forage, on present and later consumption of CF. Animals were penned individually in
Phases 1 (8 week) and 3 (2 week), and during Phase 2 (6week) wethers were kept in a pasture not containing cedar trees and were
fed wheat hay. In Phase 1 a concentrate-based diet (CBD, 12.6% CP and 35.5% NDF) was offered at approximately 85% of the
maintenance energy requirement alone (Control) or with weekly stepwise (Step) increases in level of substitution ofCFforCBD
(0, 1.25, 2.5, 5, 10, 15, 20, and 25% in week 1–8, respectively;DMbasis) or substitution of 25% CF in week 2–8 (Set). In Phase
3 (2 week), all wethers were offered the diet of 75%CBDand 25% CF as previously, without or with separate free-choice access
to low-quality grass hay. CF was harvested weekly, refrigerated and hand-mixed with CBD prior to feeding. In Phase 1, intake
of CF as a percentage of that offeredwas greater (P < 0.05) for Step versus Set in week 2–8 (week 2: 84 and 68; week 3: 86 and
48; week 4: 89 and 56; week 5: 90 and 71; week 6: 96 and 81; week 7: 93 and 63; week 8: 96 and 84), although CF intake as g per
daywas greater (P < 0.05) for Set versus Step in all but week 7 and 8. In Phase 3,CBDintakewas similar among treatments, and
hay intake when offered averaged 149, 134 and 124 g per day for Step, Set and Control, respectively. For wethers not receiving
hay,CF intake as g per day for Stepwas greatest among treatments (P < 0.05) butwas not different from treatments with offered
hay (67, 37, 30, 55, 53 and 56 g per day for Step, Set and Control without and with hay, respectively; S.E. = 7.1). Similarly, CF
intake as a percentage of that offered ranked (P < 0.05) Step > Set > Control without hay, but was not different between Step
without hay and treatments with hay (78, 41, 34, 61, 57 and 60% for Step, Set and Control without and with hay, respectively;
S.E. = 7.6). Concentrations of various blood constituents at the end of Phases 1 and 3 did not indicate adverse health effects
of CF consumption. In conclusion, gradual increases in dietary level of CF deserve further research as a potential means to
elevate present and future CF consumption, with attention also directed to effects of type and level of other feedstuffs offered.
© 2004 Elsevier B.V. All rights reserved.
