Browsing Journal of Range Management, Volume 36, Number 1 (January 1983) by Title
Now showing items 34-37 of 37
The Influence of Dietary Nitrogen Source and Drinking Water pH on Growth, Digestibility, and Nitrogen Metabolism in Lambs Fed a High Roughage DietThe influence of drinking water pH and dietary nitrogen source on the growth and metabolism of young lambs fed a high roughage diet was examined in a series of trials. Two phases of a drylot feeding trial involved a comparison of diets in which all crude protein was derived from natural sources (NATURAL) or 25% of the crude protein equivalent was derived from urea (NPN). The third phase involved a comparison of NATURAL and NPN diets and drinking water of pH 5.5 to 6.0 or pH 9.0 to 9.5. Lambs tended to perform better on the NATURAL diet, largely due to increased feed consumption. Drinking water pH had no significant effects on performance. Twelve lambs were used in 3 successive metabolism trials. In trial 1 (NATURAL vs. NPN), no significant differences were observed in dry matter, organic matter, acid detergent fiber or cellulose digestibility. Nitrogen retention was similar for NPN-fed NATURAL-or NPN-fed lambs. Trials 2 and 3 compared NATURAL and NPN diets with pH 5.5 to 6.0 or pH 9.0 to 9.5 drinking water. Small but significant (P<.05) increases in dry matter, organic matter and cellulose digestion were observed with pH 9.0 to 9.5 drinking water in trial 2, and a similar effect was noted in NATURAL-fed lambs in trial 3. Nitrogen retention was not influenced by drinking water pH. These studies with high roughage diets indicate that drinking water pH would not appear to be a major concern in the management of rangeland ruminants.
Use of Reciprocal Averaging Ordination for the Study of Range Condition Gradients in Grazed EcosystemsThe use of a multivariate ordination procedure, Reciprocal Averaging, to study species responses to grazing along range condition gradients was investigated using both artificial and field data. Results suggest that the technique should be a useful aid in the elucidation of such responses and in the study of plant-environment relationships generally in grazed ecosystems.
Vegetational Evaluation of Pinyon-Juniper Cabling in South-Central New MexicoVegetational comparisons were made between areas where pinyon-juniper vegetation had been cabled in 1954 and uncabled areas. Total tree density on the cabled areas was about 80% of that on control areas. Basal area and canopy cover of trees was substantially lower on control areas than on cabled areas. Rhus trilobata and Xanthocephalum sarothrae apparently were the only shrubby species that responded to the cabling treatment. Basal cover of Bouteloua gracilis, Eragrostis erosa, and Muhlenbergia pauciflora was significantly greater on the control areas than on the cabled area.
While-tailed Deer Food Habits and Nutritional Status as Affected by Grazing and Deer-Harvest ManagementWhite-tailed deer were collected in 1979 and 1980 from two areas in central Texas to determine differences in diets and nutritional status between years, sexes, and areas. Area 1 was more heavily populated with white-tailed deer, exotic big game, and domestic livestock than Area 2. Differences in summer and fall precipitation levels between years were reflected in altered forb and browse consumption by deer as determined from rumen contents. Differences in forb selection, oak mast consumption, and juniper browse consumption were detected between areas and were considered evidence of differences in range condition between areas. White-tails obtained from Area 1 were older than those from Area 2, but were not significantly larger in carcass weights, which also reflected the lower range condition of Area 1. Crude protein levels of rumen contents were greater in females than males and were greater in deer obtained from Area 1 than Area 2. These differences in rumen protein resulted from differences in consumption of acorns, a highly preferred, but low protein food item. Kidney fat indices reflected differences in rainfall patterns between years. Native and exotic big game populations and livestock grazing must be controlled to maintain a high level of nutritional status in the economically important white-tailed deer of central Texas.