A system for predicting energy and protein requirements of wild ruminants

Abstract

Wild ruminants require energy and protein for the normal function. I developed a system for predicting these energy and protein requirements across ruminant species and life stages. This system defines requirements on the basis of net energy (NE), net protein (NP), and ruminally degraded protein (RDP). Total NE and NP requirements are calculated as the sum of NE and NP required for several functions (maintenance, activity, thermoregulation, gain, lactation, and gestation). To estimate the requirements for each function, I collected data predominantly for wild species and then formulated allometric and other equations that predict requirements across species. I estimated RDP requirements using an equation for cattle. I then related NE, NP, and RDP to quantities more practical for diet formulation (e.g. dry matter intake). I tabulated requirements over a range of body mass and life stages (neonate, juvenile, nonproductive adult, lactating adult, and gestating adult). Tabulated requirements suggest that adults at peak lactation require greatest quantities of energy and neonates generally require greatest quantities of protein, agreeing with suggestions that lactation is energetically expensive and protein is most limiting during growth. Equations used in this system were precise (allometric equations had R(2) generally ≥0.89 and coefficient of variation <31.1%) and expected to reliably predict requirements across species. Results showed that a system for beef cattle would overestimate NE and either over- or underestimate NP for gain when applied to wild ruminants, showing that systems for wild ruminants should not extrapolate from requirements for domestic ruminants. One prominent system for wild ruminants predicted at times vastly different protein requirements from those predicted by the proposed system. The proposed system should be further evaluated and expanded to include other nutrients.

Estimating Mineral Requirements of Wild Herbivores: Modelling Arctic Caribou (Rangifer tarandus granti) in Summer

“…It is difficult to assess the direct effects of changing mineral availabilities on the movement and production of wild ungulates because mineral requirements have not been quantified for most wild species [ 12 , 17 ]. However, the requirements for wild ungulates may be estimated from those of domestic ungulates by accounting for differences in seasonal food intake, mass gain, and reproduction [ 18 ].…”

“…The observed metrics of individual production for caribou (mass change, food intake, milk production, and antler synthesis) were compiled from the literature and applied to the factorial relationships of the mineral requirements of domestic animals. Models of nutrient requirements in wild ungulates traditionally focus on their requirements for protein and energy by using the consensus of the literature regarding specific guilds of ruminants [ 29 ] or the functional relationships between net primary production, body size, and population size [ 30 ], or by incorporating data on wild ungulates into the factorial requirements of domestic ruminants [ 18 ]. Our model is the first to estimate minerals requirements by incorporating seasonal patterns in the food intake and body mass gain of a wild ungulate with factorial estimates of mineral requirements in domestic ungulates.…”