Seasonal intake determination in reproductive wapiti hinds (Cervus elaphus canadensis) using n-alkane markers

Gedir, Jay V.; Hudson, Robert J.

doi:10.4141/a99-042

Cited by 13 publications

(7 citation statements)

References 21 publications

(27 reference statements)

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“…These factors may have lead to an underestimate of forage intake. In addition, the cost of lactation may increase forage intake by 50% [77]. But these measures are consistent with conventional animal-unit calculations that also ignore forage intake by calves or lactation of adult females [22].…”

Section: Discussionsupporting

confidence: 63%

Estimating Economic Carrying Capacity for an Ungulate Guild in Western Canada

Kuzyk¹,

Cool²,

Bork³

et al. 2009

TOCONSBJ

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Elk Island National Park in western Canada provides an ideal case study for an economic carrying capacity estimate because it supports high density of four species of ungulates (11/km 2 ), lacks large predators, and is enclosed by a 2.1-meter mesh fence. This high density of ungulates has created persistent management challenges by altering vegetation structure and community composition. Using linear programming, we explored optimal allocation of forage resources for bison (Bison bison bison), moose (Alces andersoni), wapiti (Cervus elaphus manitobensis) and deer (Odocoileus virginianus and O. hemionus) to maximize ungulate biomass and numbers, when constrained by use of the major forage classes and minimum viable populations (MVP) of those ungulate species that do not cross the boundary fence (bison and wapiti). Maximum numbers of animals were achieved by a stocking combination dominated by deer and bison, whereas maximum biomass was attained when bison and moose were abundant but deer were absent. Wapiti remained at MVP during all solutions. Optimal solutions consistent with current ungulate densities were associated with 7 to 11% forage removal. This is less than normally assumed for sustainable forage use, and may reflect the need to account for other biotic and abiotic losses to forage in carrying capacity models for which ungulate densities can be constrained by availability of a preferred forage class (e.g., grass) as well as forage quality. This research extends the conventional animal-unit concept to multispecies systems and provides templates based on forage biomass allocation for resource managers facing similar problems of joint stocking in different environments.

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Section: Discussionsupporting

confidence: 63%

Estimating Economic Carrying Capacity for an Ungulate Guild in Western Canada

Kuzyk¹,

Cool²,

Bork³

et al. 2009

TOCONSBJ

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“…Date of sampling influences the alkanes concentration depending on the plant growth stage, as concentration differs between plant parts. The highest is in the florescence, at least for L. perenne (Dove et al, 1996;Ferreira et al, 2009), T. officinale, and T. repens (Gedir and Hudson, 2000). Ferreira et al (2009Ferreira et al ( , 2015 observed similar LCFA and LCOH marker profiles of L. perenne for leaf and stem fractions, and for the spike fraction, and there may be only minor differences between plant parts in other plant species, which should be tested in future studies.…”

Section: Plant Wax Concentration and Profiles Of Plant Speciesmentioning

confidence: 86%

Using plant wax markers to estimate the diet composition of grazing Holstein dairy cows

Heublein

Südekum

Gill

et al. 2017

Journal of Dairy Science

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The objective of this study was to test whether diet selection of dairy cows under grazing conditions could be estimated using plant wax markers. Furthermore, differences between 2 cow strains and the effect of concentrate supplementation on plant species selection were investigated. The experiment was a study with a crossover design performed on an organic farm with 12 Swiss Holstein cows and 12 New Zealand Holstein cows. Both experimental periods consisted of a 21-d adaptation and a 7-d measurement period. All cows grazed full time in a rotational stocking system and received either no concentrate or 6 kg/d of a commercial cereal-grain mix. Representative herbage samples of each grazed paddock were taken and botanical composition of subsamples was manually determined. The average proportions of the plant species were 27.8% Lolium perenne, 6.1% Dactylis glomerata, 10.4% Trifolium repens, and 9.0% Taraxacum officinale. Other grass species were merged as "other grass" (38.2%) and other forb species as "other forbs" (8.5%). n-Alkanes, long-chain fatty acids, and long-chain alcohols (LCOH) were analyzed in the samples of plant species, concentrate, and feces from each cow. A linear discriminant analysis indicated that diet components were differentiated best with LCOH (96%) and worst with the combination of all marker groups together (12%). For each marker, the fecal marker recovery (FR) relative to dosed ytterbium was determined in 2 ways. Estimation of diet composition was performed with the software "EatWhat," and results were compared with botanical composition with the Aitchison distance. The results indicate that the diet composition of grazing dairy cows can be estimated using plant wax markers. Additionally, the calculation of FR led to mostly reliable results, yet this approach needs further validation. The most accurate estimation was achieved with the marker combination of n-alkanes and LCOH with a correction for FR. Less accurate estimations were achieved with long-chain fatty acids alone or in combination with n-alkanes. No difference relating to diet selection between the 2 cow strains was recorded, but supplemented cows apparently ingested higher proportions of T. repens than nonsupplemented cows. Awareness that supplementation influences selection behavior of grazing dairy cows may lead to adaptations in botanical composition of the pasture according to the demand of the animals.

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“…In particular, it has been suggested that bite mass estimations may be biased and that there may be a low degree of interobserver repeatability (e.g., Gordon 1995;Forbes 2006). To explore this, several experiments tested the reliability of hand plucking for the measurement of daily intake (Meuret et al 1985;Renecker and Hudson 1985;Gedir and Hudson 2000). Reliability was generally high (i.e., over 90%), but the product of bite mass (determined by hand plucking), bite rate, and grazing time consistently overestimated intake.…”

Section: Introductionmentioning

confidence: 99%

Is Hand Plucking an Accurate Method of Estimating Bite Mass and Instantaneous Intake of Grazing Herbivores?

Bonnet

Hagenah

Hebbelmann

et al. 2011

Rangeland Ecology & Management

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Instantaneous intake is central to the understanding of large herbivore foraging strategies and rangeland ecology. Unfortunately, its measurement under field conditions remains challenging because of the difficulty of estimating bite mass. The hand plucking method provides a simple, noninvasive method of estimating bite masses and thus instantaneous intake of grazing herbivores. However, many authors questioned its accuracy and interobserver repeatability. In this study, we tested the accuracy and the repeatability of the hand plucking method using four observers and two herbivore species (i.e., cattle and goats). We compared hand plucked bite mass estimates to actual bite mass of bites taken by the herbivores on natural patches of grass. Training of the observers was fundamental to obtaining accurate bite mass measurements. The mean daily accuracy of the observers' bite mass estimates increased from 60-80% to 80-94% within 5 d. After training, the relationship between bite mass estimates and actual bite mass was linear and not significantly different from a Y 5 X relationship. This means that individual bite mass estimates were centered on the real values and thus positive and negative errors canceled each other when combined. As a result, estimates of cumulative intake over about 10 feeding stations had accuracies of over 95%. Furthermore, neither the observer identity nor the herbivore species affected the accuracy of the measurements. The categorization of bites into different size categories proved to be essential in achieving accurate measurements. When observers are trained, hand plucking is a reliable and accurate method of estimating bites mass and instantaneous intake of grazing herbivores. This has important implications for rangeland research and management, as hand plucking is often the only practicable method available for estimating instantaneous intake of freeranging herbivores. 10 estaciones de pastoreo tuvo una exactitud superior al 95%. Además, la exactitud de las estimaciones no estuvieron afectadas por los observadores ni por la especie de herbívoro. La clasificación de los bocados en diversas categorías de tamañ o, fue esencial para el logro de estimaciones exactas. Cuando se cuenta con observadores entrenados, el método de cosecha manual es un me´todo confiable y preciso para la estimación de masa de bocado y el consumo instantáneo de los herbívoros. Esto tiene implicancias importantes para la investigación y el manejo de pastizales naturales, debido a que la cosecha manual es a menudo el único método disponible, para la estimación del consumoinstantáneo de los herbívoros en pastoreo.

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Seasonal intake determination in reproductive wapiti hinds (Cervus elaphus canadensis) using n-alkane markers

Cited by 13 publications

References 21 publications

Estimating Economic Carrying Capacity for an Ungulate Guild in Western Canada

Estimating Economic Carrying Capacity for an Ungulate Guild in Western Canada

Using plant wax markers to estimate the diet composition of grazing Holstein dairy cows

Is Hand Plucking an Accurate Method of Estimating Bite Mass and Instantaneous Intake of Grazing Herbivores?

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