Age and Body Condition of Goats Influence Consumption of Juniper and Monoterpene-Treated Feed Item Type text; Article Authors Frost, Rachel A.; Launchbaugh, Karen L.; Taylor, Charles A. Citation Frost, R. A., Launchbaugh, K. L., & Taylor, C. A. (2008). Age and body condition of goats influence consumption of juniper and monoterpene-treated feed. Rangeland Ecology & Management, 61(1), 48-54. DOI 10.2111/06-160R1.1 Publisher Society for Range Management Journal Rangeland Ecology & Management Rights Copyright © Society for Range Management. Download date 23/09/2021 16:50:36 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/642924 Rangeland Ecol Manage 61:48–54 | January 2008 Age and Body Condition of Goats Influence Consumption of Juniper and Monoterpene-Treated Feed Rachel A. Frost,1 Karen L. Launchbaugh,2 and Charles A. Taylor, Jr.3 Authors are 1Post Doctoral Research and Extension Associate, Animal and Range Sciences Department, Montana State University, Bozeman, MT 59717; 2Associate Professor, Department of Rangeland Ecology and Management, University of Idaho, Moscow, ID 83844; and 3Professor, Texas Agricultural Experiment Station, Sonora, TX 76950. Abstract Redberry juniper (Juniperus pinchotii Sudworth) is an invasive, evergreen tree that is rapidly expanding throughout western and central Texas. Goats will consume some juniper on rangelands; however, intake is limited. The objective of our research was to determine how the age and body condition of goats influence their consumption of juniper and an artificial feed containing 4 monoterpenes. Two separate experiments were conducted. Experiment 1 examined the intake of redberry juniper foliage and used 39 goats either young (2 yr) or mature (. 6 yr). One-half of each age group was fed appropriate basal rations to reach either a high (HBC) or low body condition (LBC). Goats in LBC ate more (P , 0.01, 8.6 g ? kg21 body weight [BW] 6 0.7 SE) juniper than those in HBC (2.3 g ? kg21 BW 6 0.3 SE), and young animals consumed more (P , 0.05, 7.2 g ? kg21 BW 6 0.7 SE) juniper than mature goats (3.9 g ? kg21 BW 6 0.5 SE) across body condition treatments. In experiment 2, 36 goats, either young (2 yr) or mature (. 6yr)andin either HBC or LBC, were offered a synthetic ration treated with 20.8 g ? kg21 of 4 monoterpenes found in redberry juniper. Goats in LBC ate more (P , 0.01, 25.3 g ? kg21 BW 6 1.0 SE) of the terpene-treated feed than those in HBC (17.5 g ? kg21 BW 6 0.7 SE), and young animals ate more (P , 0.05, 22.5 g ? kg21 BW 6 0.8 SE) than mature goats (20.3 g ? kg21 BW 6 0.8 SE) across body condition treatments. Total intake as a proportion of body weight was also affected by body condition. Age and body condition are important factors that influence intake of chemically defended plants. A better understanding of how these attributes affect diet selection will aid livestock producers in improving grazing management. Resumen ‘‘Redberry juniper’’ (Juniperus pinchotii Sudworth) es una especie arbo´rea invasora que permanece verde todo el an˜ o y que se esta expandiendo ra´pidamente a trave´s del oeste y centro de Texas. Las cabras consumira´n algo de ‘‘Juniper’’ en los pastizales, sin embargo, el consumo es limitado. El objetivo de nuestra investigacio´n fue determinar como la edad y condicio´n corporal de las cabras influye en su consumo de ‘‘Juniper’’ y de un alimento artificial conteniendo 4 monoterpenoides. Se condujeron dos experimentos separados, el experimento 1 examino´ el consumo del follaje de ‘‘Redberry juniper’’; se utilizaron 39 cabras tanto jo´venes (2 an˜ os) como maduras (mayores de 6 an˜ os). Los grupos fueron divididos en mitades que se alimentaron con raciones ba´sicas para que alcanzara´ una condicio´n corporal alta (HBC) o baja (LBC). Las cabras con LBC comieron ma´s (P , 0.01, 8.6 g ? kg21 peso vivo [PV] 6 0.7 EE) ‘‘Juniper’’ que las de HBC (2.3 g ? kg21 PV 6 0.3 EE) y los animales jo´venes consumieron ma´s de esta especie (P , 0.05, 7.2 g ? kg21 PV 6 0.7 EE) que las cabras maduras (3.9 g ? kg21 PV 6 0.5 EE), promediando los tratamientos de condicio´n corporal. En el experimento 2, 36 cabras, tanto jo´venes (2 an˜ os) como maduras (mayores a 6 an˜ os) en condicio´n HBC o LBC, fueron expuestas a una racio´n sinte´tica tratada con 20.8 g ? kg21 de 4 monoterpenoides encontrados en el ‘‘Redberry juniper.’’ Las cabras con LBC comieron ma´s (P , 0.01, 25.3 g ? kg21 PV 6 1.0 EE) alimento tratado con los monoterpenoides que aquellas con HBC (17.5 g ? kg21 PV 6 0.7 EE), y promediando los tratamientos de condicio´n corporal, los animales jo´venes consumieron ma´s (P , 0.05, 22.5 g ? kg21 PV 6 0.8 SE) que las cabras maduras (20.3 g ? kg21 PV 6 0.8 SE). El consumo total, como proporcio´n del peso vivo, tambie´n fue afectado por la condicio´n corporal. La edad y condicio´n corporal son factores importantes que influyen en el consumo de plantas con defensas quı´micas. El entender mejor como estos atributos afectan la seleccio´n de la dieta ayudara´ a los ganaderos a mejorar el manejo del apacentamiento. Key Words: intake, Juniperus, nutrition, terpenoids This project was supported by the Initiative for Future Agriculture and Food Systems Grant INTRODUCTION 2001-52103-11215 from the US Dept of Agriculture Cooperative State Research, Education, and Extension Service. Redberry juniper (Juniperus pinchotii Sudworth) is an invasive The use of trade, form, or corporation names in this publication is for the information and evergreen tree that has been rapidly expanding throughout convenience of the reader. Such use does not constitute an official endorsement or approval by western and central Texas since the early 1900s (McPherson the US Department of Agriculture or the authors of any product or service to the exclusion of others that may be suitable. and Wright 1990). This small tree is an aggressive competitor At the time of the research, Frost was research assistant, Dept of Rangeland Ecology and with a dense branch pattern that intercepts precipitation before Management, University of Idaho, Moscow, ID 83844. it reaches the soil and has an effective lateral root system that Correspondence: Rachel A. Frost, Animal and Range Sciences Dept, Montana State suppresses growth of adjacent grasses and forbs, thereby, University, Bozeman, MT 59717. Email: [email protected] increasing the amount of bare ground. This causes a dramatic Manuscript received 22 November 2006; manuscript accepted 3 September 2007. decline in the herbaceous forage for livestock and wildlife while 48 RANGELAND ECOLOGY & MANAGEMENT 61(1) January 2008 creating conditions that further perpetuate the establishment of of herbage in sheep increased till approximately 3 yr old and juniper (Dye et al. 1995). declined thereafter. The purpose of this research was to Prescribed browsing by domestic goats has been suggested as determine whether age and body condition influenced the a method of controlling juniper invasion, even though it consumption of live redberry juniper foliage or intake of an contains monoterpenes or essential oils, which inhibit herbiv- artificial feed in which 4 monoterpenes found in redberry ory in several ways. First, monoterpenes exhibit antimicrobial juniper were added. properties that vary by concentration (Oh et al. 1967; Nagy and Tengerdy 1968) and class of monoterpenes (Oh et al. 1968). Secondly, monoterpenes limit intake presumably by MATERIALS AND METHODS producing conditioned flavor aversions from digestive malaise or illness following consumption (Estell et al. 1998, 2002; Experiment 1—Intake of Juniper Foliage Vourc’h et al. 2002). Monoterpenes found in juniper have been negatively correlated with preference by herbivores (Riddle et Conditioning Period. Research was conducted at the Texas al. 1996). A&M University (TAMU) Agricultural Experiment Station, Monoterpenes are lipophilic compounds that must be 52 km south of Sonora, TX. Thirty-nine female Boer–Spanish converted to hydrophilic substances to be excreted from the crossbred goats were selected from a herd grazing on juniper- body. This conversion process occurs in the liver and requires infested rangeland. Goats were chosen from 2 age groups: energy and nutritional resources (Foley et al. 1995). As body young (Y) were 2 yr old (n 5 20), and mature goats (M) were condition declines, animals lose functioning liver mass (Noziere greater than 6 yr of age (n 5 19). We chose these age groups to et al. 1999), further diminishing their ability to process plant explore how managers might divide their flocks into functional allelochemicals. Foley and colleagues (1995) contend that groups with potential differences in diet selection, especially animals under nutritional stress may need to adjust their consumption of chemically defended plants. Half of each age foraging strategy by decreasing consumption of toxic plants to group was randomly assigned to either a high or low body maintain homeostasis. They propose that concentrations of condition (HBC or LBC, respectively) treatment, resulting in secondary plant compounds set intake limits, and animals with four treatment combinations of age and body condition. The compromised detoxification capacity should exhibit reduced goats were maintained in individual pens with free-choice intake of plants containing secondary compounds. But, recent access to water and trace-mineralized salt. Those animals in the research with cattle in low body condition has demonstrated HBC treatment groups were offered ad libitum access to an that herbivores may behave otherwise.