The high apparent dry matter digestibility of the two smaller, nondomestic
ruminant species (the Grant's and Thomson's gazelles) is of
interest. The data suggests that these non-domestic species might be
more efficient in converting forage into protein than the other
domestic and non-domestic species investigated. It is important to
note that the Grant's and Thomson's gazelles are intermediate feeders
and as such they are more likely to alter (adapt) diet selection under
varied environmental conditions, than their larger non-domestic,
grazer counterparts (Oryx and Wildebeest). It is seen that when
expressed in terms of their respective metabolic body mass the food
intake of the gazelles is lower than that of any of the other species
investigated. Since the Grant's gazelle utilizes approximately the same
amount of food as the Turkana goat and fat-tailed sheep, and the
Thomson's gazelle only slightly more, their lowfood intake per kg 75 is likely the result of the high digestibility (Talbot et al., 1965). The data
presented also support the previous findings of Rogerson (1968) that
the wildebeest has a 20–30% higher maintenance requirement per
kg75 than that of the domestic species. Fig. 1 depicts the amount of
food digested and intake by East African ruminants given ad libitum
food and water at an ambient temperature of 22 °C.
In conclusion, for the smaller species of ruminant, food intake per
kg body mass appears to be a more meaningful expression of productivity
than that of food intake per kg 75 since the gazelles eat less
food per kilogram of body mass than their domestic counterparts, the
sheep and goat. Furthermore, these gazelles appear much more digestive
efficient than any of the other species. However, these results are
only suggestive, and a detailed investigation of digestive efficiency on
different planes of nutrition and under controlled laboratory as well as
varied field conditions needs to be conducted before definite conclusions
can be drawn. While studies are currently in progress in our
laboratory, aim at investigating the low metabolic rate and metabolic
adaptation for surviving famines in zebu cattle, it would also be
interesting to find out if small wild and domestic desert ruminants
have a “metabolic switch” for surviving food shortages inherent in arid
habitats as suggested by Merkt and Taylor, (1994) and Choshniak et al.
(1995)