Abstract
Twenty-four mature, dry, female goats were grazed on Brachiuria-dominated pasture to study the effects of tethering on
intake. Animals were either tethered for 4 h (T4) or 8 h (T8). or grazed freely for 8 h (FG) during a 28 day period. Intake was
estimated by two methods: ( 1) short-term BW changes and (2) n-alkanes as internal markers. The BW technique was suitable
for conditions in developing countries, although correction factors for changes in bite rate through the grazing day may be needed
in order to estimate total intake. The alkane technique may be more appropriate to estimate total intake, but it involves sophisticated
and expensive chemical analyses. Animals grazed for 4 h had similar total daily intakes to those grazed for 8 h: 1055 g day-‘,
1183gdayy’andl259gdayy’ for T4, T8 and FG treatments, respectively. The T4 animals compensated for the shorter time
available by increasing intake rate and spending a larger proportion of available time eating. Although the reason for higher
intake rates observed in T4 animals was unclear, duration of fasting was not considered to be a factor. Lower intake rates observed
at the end of the day for tethered animals may have resulted from decreasing herbage mass availability and soiling. Free-grazed
animals did not alter intake rate and had total intakes that did not differ from those of T8 animals. Increased rates of intake might
be expected to increase rate of passage and decrease digestibility; however, in the present trial, digestibilities (0.49, 0.54 and
0.51 for T4, T8 and FG animals, respectively) did not differ (P> 0.05) among treatments. The results showed no serious
disadvantage in terms of intake and digestibility, either of tethering per se, or of tethering for 4 h as opposed to 8 h, for mature
non-productive goats, which were able to alter behaviour to compensate for limited time available for grazing.