Browsing Journal of Range Management, Volume 51, Number 5 (September 1998) by Subjects
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Pine needle consumption by cattle during winter in South DakotaPregnant cattle that consume ponderosa pine (Pinus ponderosa (Lawson) needles often abort. The objectives of these studies were to: 1) determine needle consumption by grazing cattle; 2) relate consumption in pen-fed and grazing cattle to weather variables; and 3) determine if needle temperature influenced consumption in pen-fed cattle. Trial 1 was conducted from 3 Dec. 1991 to 12 Feb. 1992 near Custer, S. Dak. Eight mature cows grazed a 9-ha pasture. Needle consumption was measured using bite counts H. and fecal analysis. The winter was mild, and cattle consumed few needles (< 2% of bites). Trial 2 was conducted in the same location from 5 January to 2 March 1993, using 6 pregnant cows kept in pens and 5 open cows grazing the pasture. The pen-fed cows were offered 1 kg of fresh pine needles daily; methods for grazing cattle were the same as in the previous trial. Further, the pen-fed cows were offered warm or cold green needles in 2 acceptability trials. Grazing cattle consumed an average of 20% of bites as pine needles. As snow depth increased, pine needle consumption increased, particularly from short (< 2 m tall) tree (P < 0.01). The percent of bites of green needles was related (r2 = 0.69) to minimum temperature and snow depth, with greater consumption at colder temperatures and at deeper snow depths. As snow depth increased, cattle reduced daily grazing time (P < 0.01); at colder temperatures, cattle also reduced grazing time (P < 0.05). Pen-fed cows ate 483 g pine needles/day (fresh weight), with no abortions occurring. Cattle preferred cold needles to warm needles (P < 0.05) in January, despite tree size; whereas, the opposite result was noted in February. We conclude that snow depth, reduced amounts of grazable forage, and cold ambient temperatures are crucial factors in consumption of ponderosa pine needles by grazing cattle.
Technical note: A comparison of techniques for extracting monoterpenoids from Juniperus (Cupressaceae) speciesConcentration and composition of monoterpenoids in plant tissue affects a variety of environmental and ecological issues such as plant defenses, plant classification and phytotoxicity. Developing the techniques for extracting and estimating the concentration and composition of monoterpenoids must be species-specific because monoterpenoid storage location varies between species. Ashe juniper (Juniperus ashei Buchholz) and redberry juniper (J. pinchotti Sudw) are 2 co-occurring species which differ in palatability and preference. The objective of this study was to determine which of 2 common extraction techniques provided the best estimate of the concentration and composition of monoterpenoids in mature plant tissue. Two extraction techniques were tested by soaking crushed juniper needles in hexane solvent for 6, 12, 18 and 24 hours or by steam distilling samples for 2, 4, 6, or 8 hours. The extracts were analyzed by using 2 different analytical columns in separate gas chromatographs. The hexane solvent soak, regardless of time in the solvent yielded a lower total concentration and a decreased compositional diversity of monoterpenoids compared to the steam distillation technique. An 8-hour steam distillation yielded the greatest concentration and composition of monoterpenoids. Both types of analytical columns resulted in similar estimates of monoterpenoid concentrations and composition.