Suitability of NIRS analysis for estimating diet quality of free‐living red deer Cervus elaphus and roe deer Capreolus capreolus

Abstract

In this study, we tested the efficiency of near infrared reflectance spectroscopy (NIRS) to assess nitrogen content in faeces of free‐living ruminants. Faecal nitrogen (FN) content was analysed in 168 pellet groups from red deer Cervus elaphus and roe deer Capreolus capreolus in the growing season and in winter using both the standard Kjeldahl method and NIRS analysis. Estimates of nitrogen content obtained by the two methods did not differ (P > 0.1), and the correlation between FN values was significant (P < 0.001). FN content ranged within 1.10–4.58% of dry matter and, as anticipated, it was higher in the growing season than in winter in both species (P < 0.01). Faecal nitrogen values were also higher for roe deer than for red deer, although the difference was only significant in the growing season (P = 0.007). Our study confirmed that faecal nitrogen of free‐living ruminants can be accurately determined with NIRS analysis. NIRS represents a low‐cost analytical technique, which could replace conventional labourious methods and is highly promising for analyses of diet quality in free‐living ruminants.

Facts From Feces: Nitrogen Still Measures Up as a Nutritional Index for Mammalian Herbivores

“…Confirming that near-infrared spectroscopy is a valid method to measure N in feces, Kamler et al (2004) concluded that differences in FN of European roe (Capreolus capreolus) and red deer in the Czech Republic alone supported the hypothesis that European roe selected a diet higher in N than did red deer. Although the conclusion of Kamler et al (2004) has theoretical appeal, in a subsequent publication, Kamler and Homolka (2005:89, 94) conceded that direct comparisons of ''different feeding specialists'' was ''unwise'' but made numerous direct statistical comparisons anyway. In fairness, Leslie and Starkey (1985:143-144) took the same contradictory approach by statistically comparing Columbian black-tailed deer and Roosevelt elk and then cautioned that differences may not reflect N intake because ''small ruminants have .…”

“…The Grazing Land Technology Institute of the Natural Resources Conservation Service used FN from near infrared reflectance spectroscopy (vs. more expensive traditional wet chemistry techniques; cf. Kamler et al 2004) in their nationwide monitoring program to assess dietary crude protein and digestible organic matter from feces of domestic cattle (United States Department of Agriculture 2000). Other applications of FN involved domestic (Chenost 1985, de Alba Becerra et al 1998, Lukas et al 2005 (Studier et al 1994).…”

“…We identified 5 studies involving various comparisons among 13 unique species (Table 2), with 19 cumulative misapplications ( Fig. 1C; Dunbar and Bose 1991;Kamler et al 2004;Kamler and Homolka 2005;Codron et al 2006a, b), rendering conclusions, and likely management recommendations, suspect.…”

Testing Cort-Fitness and Cort-Adaptation hypotheses in a habitat suitability gradient for roe deer

“…This indicator has been extensively used in ungulates (Hamel et al, 2009 and references therein) and more precisely in roe deer (Kamler and Homolka, 2005;Kamler et al, 2004;Navarro-González et al, 2011). N was quantified by elemental analyses using the dynamic flash combustion method at 1200 C in a LECO CHNS-932analyzer (Leco, Michigan USA).…”

Evaluation of winter food quality and its variability for red deer in forest environment: overwintering enclosures vs. free-ranging areas

“…Near infrared reflectance spectroscopy (NIRS) provides a useful tool to overcome these drawbacks since it allows rapid, low-cost, chemical-free, and non-destructive analyses of a large number of samples (Foley et al 1998). NIRS has been widely used in wildlife nutrition research over the past four decades and numerous studies have used NIRS to measure food quality through faecal indices in herbivorous ungulates (Kamler et al 2004;Dixon & Coates 2009;Showers et al 2006).…”