• Instantaneous intake rates of 9 browse species by white-tailed deer

      Koerth, B. H.; Stuth, J. W. (Society for Range Management, 1991-11-01)
      Instantaneous intake rate (IIR) and instantaneous nutrient intake rate (INIR) by tame white-tailed deer (Odocoileus virginianus) of 9 common browse species in south Texas were studied to determine if morphological properties of the plants were associated with intake rate, and if IIR and INIR correlated to preference ratings derived from percent time spent foraging a particular species and with total foliage consumed. Mean leaf mass showed a significant (P < 0.05) positive correlation to IIR (r = 0.75), INIR of neutral detergent fiber (r = 0.73), acid detergent fiber (r = 0.73), and acid detergent fiber nitrogen (r = 0.68). Mean leaf length showed a significant (P < 0.05) positive correlation to INIR of crude protein (r = 0.67). Thorn density showed no significant (P > 0.05) correlations to IIR or INIR. Leaf weight/stem weight ratio showed a significant (P < 0.05) positive-correlation to IIR (r = 0.65) and INIR of acid detergent fiber nitrogen (r = 0.81). Rankings of IIR and INIR did not agree with preference indices based on weight of forage removed or amount of time spent browsing. Significant (P < 0.05) positive correlations for all trials between preference indices based on weight removal and time spent browsing (r = 0.73 for new leaf development, r = 0.87 for stem elongation, and r = 0.70 for full leaf development) indicated these 2 techniques closely agreed on species rank.
    • Nutrient intake of cattle on rotational and continuous grazing treatments

      McKown, C. D.; Walker, J. W.; Stuth, J. W.; Heitschmidt, R. K. (Society for Range Management, 1991-11-01)
      Many benefits have been obtained from rotational grazing, including management flexibility and livestock distribution, but long-term positive effects on plant and animal production have been inconsistent. The purpose of this cast study was to investigate nutrient intake of animals in 2 production scale grazing, treatments. The study site was the Texas Experimental Ranch located in Throckmorton County, in the eastern portion of the Rolling Plains of Texas. Treatments were a 465-ha, 16-paddock, 1-herd, cell designed rotational grazing system (RG) stocked at a heavy rate (3.7 ha cow-1 yr-1) and a 248-ha continuously grazed (CG) treatment stocked at a moderate rate (6.2 ha cow-1 yr-1). Size of RG paddocks was varied to create different livestock densities to simulate rotational grazing at a 14 and 42 paddock level. Comparisons were made to determine the effect of type of grazing system (RG vs. CG) and the effect of livestock density within the RG system on nutrient intake. Nutrient intake of esophageally fistulated steers was determined by daily dosing them with ytterbium nitrate-labeled forage and collection of fecal samples plus collection of fistula extrusa samples for crude protein and in vitro organic matter digestibility determinations. The only difference caused by different livestock densities was a higher (P < 0.001) intake of forage crude protein in the simulated 42 paddock system. Nutrient intake of steers in the CG treatment was greater (P < 0.001) than those in the RG treatment. Differences between treatment were attributed primarily to differences in stocking rate rather than grazing system.