Browsing Journal of Range Management, Volume 47, Number 4 (July 1994) by Subjects
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Cattle grazing white locoweed in New Mexico: Influence of grazing pressure and phenological growth stageLocoweed poisoning generally occurs in early spring when other forage is dormant or in short supply and locoweed is the main green plant available to grazing livestock. The objective of this study was to estimate the amount of white locoweed (Oxytropis Sericea Nut. ex T&G) consumed by cattle, and to determine if cattle graze locoweed because it is relatively palatable, or if they are forced to graze it because of decreasing availability of other forage. Three grazing trials were conducted that corresponded to the vegetative, flower, and pod phenological growth stages of white locoweed. Four cows were used in Trial 1 (vegetative growth stage), and 7 cows were used in Trials 2 (flower stage) and 3 (pod stage). Pastures were fenced for the 10-day grazing trials, so that forage became limited and grazing pressure increased as the trials progressed. Acceptance of white locoweed at the beginning of each trial, when there was adequate forage, would indicate preference. Rejection of white locoweed at the beginning of the trials, followed by increasing consumption as the trials progressed would indicate that grazing pressure was forcing the cows to select white locoweed. White locoweed was readily accepted by 1 cow in the vegetative trial, and by 2 cows in the flower trial (these cows were termed "loco-eaters"). The remainder of the cows (termed "normal") rejected white locoweed in the vegetative and flower trials until the availability of new growth cool n grasses decreased, after which they started to select white locoweed. AD cows rejected white locoweed at the beginning of the pod trial but consumed it as availability of other plants decreased. Regression analysis showed that grazing pressure was positively associated with ingestion of white locoweed (r2 = .46 to .88) by the "normal" cows.
Protein supplementation of stocker cattle in the Northern Great PlainsA comparison of the response of varying classes of growing beef cattle to protein supplementation was conducted on Northern Great Plains rangeland during the summer and early fall. Response was evaluated in 2 experiments, conducted in 1988 and 1989, by measuring organic matter intake and body weight gain in 13-month-old (spring-born steers) and 7-month-old steers (fall-born steers), which received either a 26% crude protein supplement or no supplement. Weight gain was also monitored in 7-month old heifers (fall-born heifers). In experiment 1, spring-born steers were fed 1.28 kg and fall-born steers and heifers 1.64 kg of protein supplement every other day. During experiment 2, spring-born steers were fed supplement at a rate of 1 kg and fall-born steers and heifers at 1.8 kg every other day. Intake of forage organic matter for steers was not affected (P > 0.10) by supplementation in either experiment. In experiment 1, total organic matter intake tended to be increased by protein supplementation in June but not in August (date X supplementation level interaction, P = 0.08). Forage organic matter digestibility was greater (P < 0.01) in June than in August during experiment 1 and in August than September in experiment 2. In experiment 1, this difference was greater for fall-born steers than spring-born steers. In experiment 1, supplementation increased (P < 0.01 average daily gain of cattle from 0.63 to 0.78 kg/day. In experiment 2, daily pin of cattle was increased (P < 0.01) from 0.62 0.82 kg/day with protein supplementation. Also, in experiment 2, cattle receiving supplement were 18 kg heavier (P < 0.05) at the end of the grazing season than unsupplemented controls. Protein supplementation increased weight pins of growing cattle in the late summer in the Northern Great Plains. The advantage was most consistent for fall-born steers with higher relative protein requirements.
Storms influence cattle to graze larkspur: an observationLivestock producers report cattle deaths from larkspur (Delphinium spp.) poisoning increase during stormy periods. In controlled grazing studies, we observed cattle increase larkspur consumption during stormy weather. Periods of "gluttonous" larkspur consumption generally coincided with storms during a 1990 grazing study. Cattle consumed larkspur almost exclusively for 20-30 min periods during storms, as opposed to intermittent grazing of larkspur flowers, pods, and leaves. In 1991 weather parameters were measured and correlated with larkspur consumption. Larkspur consumption was negatively correlated with decreasing temperature and barometric pressure (r = -0.45 and -0.60 respectively); and positively correlated with increasing relative humidity, leaf wetness, and precipitation (r = 0.45, 0.74, and 0.27, respectively). Understanding consumption patterns of cattle grazing larkspur will aid in developing management strategies to reduce cattle deaths.