A global comparison of the nutritive values of forage plants grown in contrasting environments

Mark A Lee

doi:10.1007/s10265-018-1024-y

Abstract

Forage plants are valuable because they maintain wild and domesticated herbivores, and sustain the delivery of meat, milk and other commodities. Forage plants contain different quantities of fibre, lignin, minerals and protein, and vary in the proportion of their tissue that can be digested by herbivores. These nutritive components are important determinants of consumer growth rates, reproductive success and behaviour. A dataset was compiled to quantify variation in forage plant nutritive values within- and between-plant species, and to assess variation between plant functional groups and bioclimatic zones. 1255 geo-located records containing 3774 measurements of nutritive values for 136 forage plant species grown in 30 countries were obtained from published articles. Spatial variability in forage nutritive values indicated that climate modified plant nutritive values. Forage plants grown in arid and equatorial regions generally contained less digestible material than those grown in temperate and tundra regions; containing more fibre and lignin, and less protein. These patterns may reveal why herbivore body sizes, digestion and migration strategies are different in warmer and drier regions. This dataset also revealed the capacity for variation in the nutrition provided by forage plants, which may drive consumer species coexistence. The proportion of the plant tissue that was digestible ranged between species from 2 to 91%. The amount of fibre contained within plant material ranged by 23–90%, protein by 2–36%, lignin by 1–21% and minerals by 2–22%. On average, grasses and tree foliage contained the most fibre, whilst herbaceous legumes contained the most protein and tree foliage contained the most lignin. However, there were individual species within each functional group that were highly nutritious. This dataset may be used to identify forage plant species or mixtures of species from different functional groups with useful nutritional traits which can be cultivated to enhance livestock productivity and inform wild herbivore conservation strategies.

Highlights

Forage plants provide humans with valuable ecosystem services, for example, they feed an estimated 1.5 billion cattle, 1.2 billion sheep, 1 billion goats and 0.2 billion buffalo around the world—supplying meat, milk and other commodities (FAOSTAT 2016)
There was a larger range of values for organic matter digestibility (OMD) than for Dry matter digestibility (DMD), with digestibility ranging from 2 to 91% and from 31 to 97%, for the two metrics, respectively
The metrics with the largest ranges represented the largest number of different plant species, since CP was recorded from 129 species, NDF was recorded from 113 species and ADF was recorded from 100 species. The exception to this was dry matter content (DM) which was recorded from 67 forage plant species

Summary

Introduction

Forage plants provide humans with valuable ecosystem services, for example, they feed an estimated 1.5 billion cattle, 1.2 billion sheep, 1 billion goats and 0.2 billion buffalo around the world—supplying meat, milk and other commodities (FAOSTAT 2016). Plants vary in the quantities of different nutritive components that they deliver to consumers They can vary in the amounts of fat, protein, carbohydrate, fibre and other micro-nutrients that are present in tissues. Forage plants vary in their palatability, with defensive or structural compounds such as lignin and fibrous compounds reducing the amount of plant

Methods

Results

Discussion

Conclusion