Abstract :
Plant secondary metabolites (PSM) and nutrients can influence patterns of feed intake of
small ruminants. Their effects depend on the type and amounts of PSM and nutrients fed.
We hypothesized that one-seed juniper intake of goats and sheepwould change in response
to seasonal variations of PSM concentrations and type and amount of CP fed. To test this
hypothesis, we fed 12 does (46.7±1.25 kg) and 12 ewes (74.9±1.23 kg) freshly harvested
one-seed juniper branches in summer, fall, winter, and spring. Animals also received isoenergetic
diets (1.6% BW) with either addition of a high rumen degradable (RDP, 12.5% CP) or
undegradable (RUP, 12.5% CP) protein source or with no addition of supplemental protein
(Control, 5% CP). Juniper branches were offered in unrestricted amounts for 30 min prior to
feeding treatment diets and short-term intake was determined for 10 d per season. Oneseed
juniper leaves contained a diverse mix of terpenes, phenolics, and condensed tannins
which were positively correlated to each other (P < 0.05) and varied seasonally in concentration
and composition (P < 0.05). Juniper intakewas greater for goats than sheep (P < 0.05),
and twice as high for animals fed high CP diets vs. control animals (P < 0.05). Juniper intake
in the fall, when levels of plant secondarymetaboliteswere highest,was 41, 58, and 52% less
(P < 0.05) than in summer, winter, and spring, respectively. Addition of high RDP and RUP
sources into diets induced different patterns of juniper intake across seasons, herbivores,
and individual animals. In each diet treatment, a distinct subset of a few PSM explained
30–78% of overall variation in juniper intake of goats and sheep. This study suggests that
increases in dietary protein levels can increase voluntary intake of one-seed juniper of small
ruminants during seasons when PSM levels are low. Diets with protein sources of different
degradability can potentially influence juniper intake of small ruminants differently, probably
due to different nutrient–PSM associations that may result in different detoxification
capabilities and post-ingestive experiences that influence individual juniper preference.
