• Evaluation of fecal indicators for assessing energy and nitrogen status of cattle and goats

      Nunez-Hernandez, G.; Holechek, J. L.; Arthun, D.; Tembo, A.; Wallace, J. D.; Galyean, M. L.; Cardenas, M.; Valdez, R. (Society for Range Management, 1992-03-01)
      In vivo digestibility trials involving cattle (steers) and goats (wethers) fed shrub and nonshrub mixtures were conducted to evaluate the potential of fecal output, fecal nitrogen output, and fecal nitrogen percent for assessing diet intake, nitrogen balance, and digestibility. Two cattle digestion trials involving 8 feeds and 4 goat digestion trials involving 13 feeds were used to develop simple linear and multiple regression equations between fecal and diet characteristics. Crude protein percent (organic matter basis) of cattle diets ranged from 3.9 to 12.0%; that of goats ranged from 7.5 to 14.4%. Low-phenolic and high-phenolic shrubs were fed in separate diets to goats while cattle diets involved only low-phenolic shrubs. Fecal output of organic matter (percentage of body weight) was correlated (r2>0.80) with forage organic matter intake (percentage of body weight) for both cattle and goats when all feeds were included in the regression. Linear regression intercepts, but not slopes, differed (P<0.05) among cattle and goats. Multiple regression equations did not improve evaluation of forage intake over simple linear equations using fecal output. Fecal nitrogen output (g N/kg BW) was associated more closely with nitrogen balance (g N/kg BW) than other fecal indicators. Further, fecal N output was best associated with nitrogen bahmce for both cattle and goats (r2 = 0.64, 73, respectively) when used in multiple regression equations. Multiple regression equations showed potential for evaluating nitrogen intake (g N/kg BW) of both cattle and goats, (R2 = 0.91, 0.87, respectively). Although it is doubtful that our equations have broad applications, our approach might be useful if specific equations were developed for individual range types.
    • Influence of two native shrubs on goat nitrogen status

      Boutouba, A.; Holechek, J. L.; Galyean, M. L.; Nunez-Hernandez, G.; Wallace, J. D.; Cardenas, M. (Society for Range Management, 1990-11-01)
      In vivo digestibility trials were conducted in metabolism stalls at New Mexico State University to evaluate the influence of leaves of true mountain mahogany (Cercocarpus montanus Raf.) and fourwing saltbush (A trtriplex canescens [Pursh.] Nutt.) on nitrogen retention and digestibility by Angora goats. Each of the 2 shrubs were fed at 3% and 6% (air dry basis) of the diet along with prairie hay that was comprised mostly of blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex. Griffhhs). High and low shrub diets contained about 12% and 8% crude protein, respectively. Nitrogen retention did not differ (P>0.05) among mountain mahogany and fourwing saltbush diets; however, goats fed the 60% shrub level had greater (P<0.05) nitrogen retention than did those fed the 3% level. Mountain mahogany diets had a greater soluble phenolic/-tannin content than fourwing saltbush diets, but this did not appear to influence nitrogen retention. Forage organic matter intakes averaged 2.0% of body weight and did not differ (P>0.05) among the 4 treatments. Total fecal output of nitrogen (g/d) was highly correlated (R2 = .71, n = 15) with nitrogen retention. Hence, total fecal nitrogen output may be useful as an indicator of grasing ruminant protein status. Digestible protein (%) and dietary crude protein concentrations were associated poorly with nitrogen retention in our study. Blood serum analysis showed no toxicosis problem for any of the 4 dietary treatments. We concluded that leaves from fourwing saltbush and true mountain mahogany have potential to he an effective source of protein for range livestock consuming low-quality grasses.
    • Mountain mahogany and cottonseed meal as supplements for grass hay

      Nunez-Hernandez, G.; Wallace, J. D.; Holechek, J. L.; Galyean, M. L.; King, D. W.; Kattnig, R. M. (Society for Range Management, 1991-09-01)
      Sixteen wether lambs (avg weight 34.5 kg) were used to study the influence of 2 sources of supplemental protein, leaves of mountain mahogany (Cercocarpus montanus Raf.) and cottonseed meal, on N digestibility and balance, forage digestibility, and voluntary intake by sheep fed a low-quality grass hay. Treatments were grass hay alone (C), C plus cottonseed meal, C plus mountain mahogany, and C plus mountain mahogany and cottonseed meal. All supplements provided 42 g of supplemental crude protein per head daily. Treatments were assigned to wethers within blocks according to a randomized complete block design. Supplemental N increased (P < 0.01) N digestibility and balance regardless of source; however, lambs supplemented with mountain mahogany digested less (P < 0.01) N, but their N balance did not differ (P > 0.10) from those supplemented with cottonseed meal. Wethers supplemented with mountain mahogany plus cottonseed meal ate more (P < 0.05) organic matter (OM) than the average consumed by those given either of the 2 supplements alone. Protein supplementation did not affect (P > 0.05) OM or fiber digestibility. Range management practices that encourage dormant season utilization of mountain mahogany by ruminants in the Southwest could reduce supplemental protein needs; such practices might include reserving mountain mahogany sites for winter use as well as greater use of mountain mahogany (and other palatable, highly nutritive shrubs) in range restoration programs in mountainous areas.
    • Seeded wheatgrass yield and nutritive quality on New Mexico big sagebrush range

      Holechek, J. L.; Estell, R. E.; Kuykendall, C. B.; Valdez, R.; Cardenas, M.; Nunez-Hernandez, G. (Society for Range Management, 1989-03-01)
      Establishment, yield, and nutritional quality of 'Nordan' crested wheatgrass (Agropyron desertorum [Fischer ex Link] Schultes), 'Fairway' crested wheatgrass (Agropyron cristatum [L.] Gaertner), 'Arriba' western wheatgrass (Pascopyrum smithii [Rydb.] A. Love), 'Luna' pubescent wheatgrass (Thinopyrum intermedium subsp. barbulatum [Schur.] Barkw. and D.R. Dewey), and 'Largo' tall wheatgrass (T. ponticum [Pod] Barkw. and D.R. Dewey) were evaluated on big sagebrush range (Artemisia tridentata Nutt. tridentata) in northcentral New Mexico during a 5-year study. All the above wheatgrasses showed high initial densities and long-term persistence. Wheatgrass yields across years and seasons during the last 2 years of study averaged 760 kg/ha compared to forage yields of 355 kg/ha on surrounding ungrazed native rangeland. There were no differences (P > .05) among wheatgrasses in standing crop of current year's growth during spring, summer, or fall. Crude protein concentrations did not differ (P > .05) among wheatgrasses with seasonal advance. However, all the wheatgrasses showed a consistent decline in nutritional quality from spring to summer to fall. All the wheatgrasses we studied will provide high-quality, spring (mid-April to mid-June) forage for livestock. During summer, use of native range is advantageous because it contains a high component of warm season grasses and forbs. Interseeding shrubs in wheatgrass seedings could reduce protein supplementation costs in winter.