Last update: August 15, 2011 09:13:33 AM E-mail Print


Energy expenditure in free-grazing goats and sheep using isotopic bicarbonate.

M.J. Herselman , T. Sahlu, S.P. Hart, K. Tesfai, R. Puchala and S. W. Coleman

E (Kika) de la Garza Institute for Goat Research, Langston University, Oklahoma and USDA-ARS, Grazingland Research Laboratory, El Reno, Oklahoma.


The objective of this study was to determine energy expenditure in different breeds of small ruminants grazing different pasture types. Energy expenditure was measured by the carbon dioxide entry rate technique in 60 free-grazing animals (10 Angora and 10 Spanish goats and 10 Suffolk x Rambouillet sheep on each of two pasture types). The animals were kept on either three paddocks (0.7 ha each) of mature Old World Bluestem grass (Bothriochloa caucasica; Bluestem) or three paddocks (10.8 ha each) of native range. Steps walked were recorded with pedometers and fecal output was measured daily. Behavioral observations were made during one of three 24-h periods of saliva collection. Body weight, fecal output (FO), CO2 entry rate (ER) and energy expenditure (BE) of Angora (ANG) and Spanish (SPN) goats and Suffolk x Rambouillet sheep (SHP) are summarized in the table below.

  Bluestem Native Past Breed
Body weight, kg 30.2 33.7 32.7 30.5 30.8 30.0 .0805 .3638
FO, 12.4 19.8 19.9 19.2 18.3 23.9 .0452 .0106
ER, 28.0 33.5 38.3 32.8 35.1 40.5 .0038 .0001
EE, 137 161 182 158 168 192 .0034 .0001


Energy expenditure was linearly related to fecal output (P < .01) and was also correlated with steps walked (r = .28; P < .1), time spent grazing (r = .52; P < .01) and resting (r = -.60; P < .01). After adjustment for fecal output (indicative of intake) energy expenditure was still different among breeds (P < .001) and pastures (P < .01). These data suggest a slight increase in energy expenditure for native over Bluestem pastures. Sheep expend more energy than goats, possibly due to longer grazing and walking times.



J. Anim. Sci. (Suppl 1), 186