Effects of gut treatment on recovery and germinability of bovine and ovine ingested seeds of four woody species from the Sudanian savanna in West Africa

Abstract

Passage rate through the digestive tracts of zebu cattle and sheep, and subsequent germination of egested seeds of four woody species from the Sudanian savanna, Acacia dudgeoni , Acacia seyal , Burkea africana and Prosopis africana , were studied. The result indicates large differences in passage rate among woody species, as well as between animals. The values ranged from 46% to 87% for seeds ingested by cattle while the lowest passage rate was 2.3% and the highest being 74% for seeds ingested by sheep. Among plant species, seeds of Prosopis africana had the highest passage rate through the digestive tract of both cattle and sheep. Seed passage through the gut showed a significant positive correlation with seed mass and thickness for cattle and sheep, respectively. The gut treatment and the retention time in the gut did not improve germination capacity and the speed of germination of dormant seeds. For non-dormant seeds of Acacia dudgeoni , the germination capacity was higher for seeds ingested by cattle than sheep. The speed of germination was also significantly higher for egested seeds than the control. It can be concluded that large herbivores could play an essential role in long distance dispersal of seeds. Gut treatment alone was not effective in breaking seed coat-imposed dormancy, although it enhanced the rate of germination of non-dormant seeds. To get a complete picture of the effect of frugivore on the release of seed dormancy, the combined effect of initial mastication and subsequent gut treatment needs to be investigated.