Browsing Journal of Range Management, Volume 51, Number 5 (September 1998) by Authors
Mineral-salt supplement does not attenuate tall larkspur (Delphinium barbeyi) toxicosis in cattlePfister, J. A.; Cheney, C. D.; Gardner, D. R.; Manners, G. D. (Society for Range Management, 1998-09-01)Severe livestock losses caused by tall larkspur (Delphinium spp.) consumption have caused many producers to try various preventative measures, including the use of mineral-salt supplementation. The objective of tbis study was to determine if additions or deletions of a mineral-salt supplement (Binn's #1 Alleviator) would alter the response (i.e., rate of nose pressing) of cattle to tall larkspur exposure. The dose response of 5 Jersey steers was examined by systematically adding 0.25 mg of mineral-salt/kg body weight, and comparing responses in the same steers without salt supplements. Steers were then run under a variable ratio (VR) reinforcement schedule and periodically dosed with tall larkspur at a level causing a significant decrease in responding without provoking overt signs of intoxication. Response rate with and without mineral-salt supplement was the major dependent variable; 3 to 5 "on-off" cycles were conducted for each subject. Steers reduced (P < 0.05) their rate of grain intake by 34% during operant sessions when larkspur was dosed compared to the previous non-dosed 3-day baseline. Rate of nose pressing was reduced (P < 0.01) on tall larkspur dose days by 28% vs. the 3-day non-dosed baseline. This reduction was indicative of the effects of the effects of subclinical larkspur intoxication on steers. On days when larkspur was dosed and animals were intoxicated, the addition of mineral did not alter (P > 0.1) grain intake (1.64 +/- 0.17 kg/session) compared to days when no mineral was given (1.76 +/- 0.13 kg/session). On larkspur dose days (i.e. when animals were intoxicated), the average response rates were 82.9 +/- 3.7 and 85.8 +/- 4.0 responses/min (P > 0.1) when off and on mineral, respectively. We concluded that mineral/salt supplementation had no effect on the response of steers to doses of tall larkspur that produced subclinical intoxication.
Pine needle consumption by cattle during winter in South DakotaPfister, J. A.; Panter, K. E.; Gardner, D. R. (Society for Range Management, 1998-09-01)Pregnant 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.