Influence of Forest Management and Previous Herbivory on Cattle Diets

Abstract

Grazing cattle and timber harvest are common practices associated with forested rangelands. Therefore, the objective was to document the effects of timber harvest and herbivory on nutritional quality and botanical composition of steer diets in grand fir (Abies grandis [Dougl. ex D. Don] Lindl.) and ponderosa pine (Pinus ponderosa P. & C. Lawson) forests. Three replicated grand fir sites were arranged as a split-plot design; timber harvest treatments-1) no harvest (CON), 2) thinning (TH), 3) clearcut (CL)were whole plots, and herbivory treatments-1) large ungulate grazing (Graze), 2) wild ungulate grazing (CExc), and 3) exclusion of large ungulate grazing (TExc)-were the subplots. Three replicated ponderosa pine sites were arranged as a split-plot design; timber harvest treatments-1) CON and 2) TH-were whole plots, and herbivory treatments-1) GR, 2) BG, and 3) EX-were subplots. Diet samples were collected in June and August of 2001 and 2002. Crude protein, in vitro organic matter digestibility, acid detergent fiber, and neutral detergent fiber of the diets were only affected by season of use and were higher (P , 0.05) quality during the June grazing period. Botanical composition of diets was determined with the use of microhistological analysis of ruminal masticate. Within grand fir sites, graminoids were the major constituent in the diet (65%-91%), forbs intermediate (8%-31%), and shrubs least (0.2%-3.5%). Within ponderosa pine sites graminoids were the major constituent in the diet (83%-88%), forbs intermediate (10%-14%), and shrubs least (2%-3%). Season of use did not affect (P. 0.10) botanical composition in either grand fir or ponderosa pine sites. Timing of grazing had a greater influence on diet quality; however, previous herbivory and(or) timber harvest had a greater influence on composition of diets than did timing of grazing. Resumen El apacentamiento del ganado y la cosecha de madera son prá cticas comunes en los pastizales boscosos. Los objetivos de este estudio fueron documentar los efectos de la cosecha de madera y herbivoría en la composició n botá nica y calidad nutricional de las dietas de novillos en bosques de ''grand fir'' (Abies grandis [Dougl. ex D. Don] Lindl.) y ''ponderosa pine'' (Pinus ponderosa P. & C. Lawson). Tres sitios repetidos de ''grand fir'' se arreglaron en un diseñ o de parcelas divididas y los tratamientos de cosecha de madera: 1) sin cosecha (CON), 2) aclareo (TH), y 3) corte (CL) fueron las parcelas principales y los tratamientos de herbivoría 1) apacentamiento de grandes ungulados (Graze), 2) apacentamiento de ungulados silvestres (CExc), y 3) la exclusió n a los grandes ungulados (TExc) fueron las subparcelas. De la misma forma tres sitios repetidos de ''ponderosa pine'' se arreglaron en un diseñ o de parcelas divididas y las parcelas principales fueron los tratamientos de cosecha de madera 1) CON y 2) TH y los tratamientos de herbivoría 1) GR, 2) BG y 3) EX fueron las subparcelas. Las muestras de las dietas fueron colectadas en Junio y Agosto del 2001 y 2002 usando cuatro...

Stocking Rate and Fuels Reduction Effects on Beef Cattle Diet Composition and Quality

“…Diet composition by forage class is presented in Table 1. Grasses made up the greatest proportion of all cattle diets, coinciding with other regional studies by Miller and Krueger (1976), Holechek et al (1982a), and Walburger et al (2007). Grass consumption was lower in the control pastures (P , 0.05) and tended (P¼0.095) to decrease with increased stocking rates.…”

“…In order to use frequency data for an estimate of vegetation composition, we divided the frequency of an individual species by the sum of all the vegetation frequencies. This analytical approach has been used in other procedures (Holechek and Gross 1982;Walburger et al 2007). However, this analytical approach assumes that frequency measurements are equivalent to weight estimates by species, and, as a result, may overestimate species that have a significant cover canopy yet lack production weight (shrubs and some forbs).…”

Dormant season grazing on northern mixed grass prairie agroecosystems: Does protein supplement intake, cow age, weight and body condition impact beef cattle resource use and residual vegetation cover?

“…Limited forage availability likely caused animals to consume a greater proportion of the less-preferred forage [84], and focus grazing efforts in areas where less snow had accumulated. Our data supports this behavioral response as grazing intensity had little to no effect on grass cover in year one, even though cattle have strong dietary preference for grass [79][80][81]. However, the second year of the grazing trial resulted in a strong negative association between grass cover and grazing intensity.…”

“…Virtually any grazing resulted in an increase in forb cover that rapidly met a threshold. Cattle typically have a strong dietary preference for grasses [79][80][81]. Thus, increases in forb cover with grazing intensity is likely an artifact of cattle removing grass biomass via grazing, increasing forb detection during the post-grazing vegetation data collection period.…”

Influence of forest series and stand age on the growing season nutritional dynamics of plant growth forms in a mixed-conifer forest

“…Though it has been well established how the forage quality of plant growth forms (graminoids, forbs, and shrubs) fluctuate over the growing season, this information is limited for mixed-conifer forests ( Skovlin, 1967 ; Clark, 2003 ). Timber harvest sets back succession, resulting in younger forest stands and increased understory forage production ( Miller and Krueger, 1976 ; Walburger et al, 2007 ), however, little information is known about how stand age influences forage quality ( Regelin et al, 1974 ; Severson and Uresk, 1988 ).…”