Dietary Selection by Domestic Grazing Ruminants in Temperate Pastures: Current State of Knowledge, Methodologies, and Future Direction

Abstract

Ruminants grazing mixed-species pastures face many choices, including when and where to graze and how much herbage to consume. These choices affect not only the nutritional status of the animal, but also sward composition and nutritive value through selective defoliation. Limited research has been conducted in the area of dietary selection and preference, most of which has been limited to simple model systems often involving a choice between only two herbage species. Although these studies have provided a vital tool to allow understanding of the fundamental principles of foraging behavior, in reality, grazing ruminants are faced with more complex situations. Understanding and managing animal preferences in mixed swards and thereby altering dietary selection can result in greater primary (plant) and secondary (animal) productivity. Key issues to improve this understanding include a better linking of behavioral and nutritional studies, a better understanding of the genetic factors influencing diet selection, and the development of more explicit spatial models of foraging behavior that incorporate multiple scales of decision making. This article, as part of a set of synthesis articles, reviews the current state of knowledge and research methodologies related to diet selection of grazing domestic ruminants with particular reference to improved temperate grazing environments, including how well we understand each part of the complex decision-making process a grazing ruminant faces, the links with primary and secondary productivity, and developments in methodologies. Finally, we identify key areas where knowledge is lacking and further research is urgently required. Resumen Los rumiantes en condiciones de libre pastoreo tienen diferentes opciones, incluyendo cuando y donde pastorear y cuanto forraje consumir. Estas opciones afectan no sólo el estado nutricional del animal, sino también la composición y valor nutritivo de las especies a través de pastoreo selectivo. La investigación en el área de selección de dieta y preferencia es escasa, y principalmente se limita a un modelo simple de dos especies Estos estudios han proporcionado una herramienta vital para entender los principios fundamentales del comportamiento del pastoreo, en realidad los rumiantes en pastoreo enfrentan situaciones más complejas. Comprender y manejar la preferencia del animal en potreros mixtos, y manipular la selección de la dieta puede resultar en una mayor producción primaria (planta) y secundaria (animal). Algunos elementos claves que ayuden a conocer este proceso son una mejor relación entre estudios de comportamiento y nutricionales, un mayor entendimiento de los factores genéticos que afectan la selección de la dieta, y el desarrollo de modelos espaciales de comportamiento en pastoreo incorporando diferentes escalas en la toma de decisiones. El presente trabajo, como parte de un conjunto de manuscritos, revisa el nivel de conocimiento así como la metodología relacionados con la selección de la dieta por rumiantes en pastoreo con particular ...

Seasonal diet preference of cattle, sheep and goats grazing on the communal grazing rangeland in the Central District of Botswana

“…As reported by Storr (1961);Free et al (1970);Soder et al (2009); Kilonzo et al (2005), the technique was also Means within each animal species followed by the same letter are not significantly (P>0. 05) different.…”

“…Selective grazing, due to differences in relative plant palatability, is a problem confronting people concerned with the practices of correct range utilization. Two forms of selective grazing, namely species selective grazing and area selective grazing were identified (Bailey, 1995;Soder et al, 2009;Masahiko et al, 2008). The causes for differences in palatability among both grasses and other life forms are as yet not clearly understood in spite of the fact that numerous attempts had been made in the past to relate preference differences to a number of factors such as forage quality (Bailey, 1995;Van Dyne and Heady, 1965;O'Reagain and Mentis, 1989;Soder et al, 2009), frequency of grazing and forage available in the range (Gammon and Roberts, 1978;Darlene et al, 2005;Kilonzo et al, 2005).…”

“…The faecal technique is increasingly advocated to avoid the disadvantages of other methods for developing diet of free-ranging ruminants (Sparks and Malcheck, 1968;Smith and Shandruk, 1979;Kilonzo et al, 2005;Soder et al 2009). This method examines and depends on the identification of indigestible cutinised fragments of leaves persisting in the faeces (Storr, 1961;Sparks and Malcheck, 1968;Liversidge, 1970;Scotcher, 1979;Holechek and Gross, 1982;Kilonzo et al, 2005;Soder et al, 2009). However, the epidermal tissues of forbs were not as easily found in cattle and sheep faeces (Free et al, 1970).…”

“…In winter, however, the two methods were found to be comparable. Most scientists however, agree that differential digestion of plant species has little or no influence on the proportion of identifiable plant fragments (Free et al 1970;Anthony and Smith 1974;Dearden et al, 1975;Alipayo et al, 1992;Kilonzo et al, 2005;Soder et al, 2009). Diet composition data alone are not sufficient to explaining the reason for observed diet differences between animal species, or switching of diet through the seasons.…”

“…Such knowledge can be used in the assessment of nutrient intake of animals and evaluation of forage competition or complementary between herbivores (Holechek and Gross, 1982;McInnis et al, 1983;Hendricks et al, 2002;Kilonzo et al, 2005;Lou et al, 2004;Soder et al, 2009). This research was aimed at evaluating goats, sheep and cattle diet composition, diet overlap, and forage preference on communal grazing rangeland in Central District of Botswana to understand potential for forage competition to provide better ideas for managing these rangelands.…”