Seed recovery of native plant species of the Caatinga biome ingested by goats and its effect on seed germination, in Brazilian semiarid region

Abstract

The plant species of the Caatinga biome are food sources of great importance for herds. Goat farming is one of the most explored agricultural activities in the Northeast region of Brazil, where goats are important seed dispersers in semiarid areas. In this study, we evaluate the passage of seeds of four Caatinga forest species through goats’ digestive system, their recovery, and the effect on seed germination (Ger). A completely randomized experimental design was used. The seeds of four species Piptadenia stipulacea, Mimosa tenuiflora, Desmanthus virgatus, and Mimosa caesalpiniifolia were provided to eight goats and evaluated after nine excretion periods (12, 24, 36, 48, 60, 72, 84, 96, and 108 h). Seed recovery was low, with values of 10.87% for M. tenuiflora, 3.41% for P. stipulacea, 2.04% for M. caesalpiniifolia, and 1.54% for D. virgatus. The seeds of D. virgatus and M. tenuiflora are small and pass faster through goats’ digestive system, with the largest amount recovered 48 h after ingestion. In contrast, P. stipulacea and M. caesalpiniifolia seeds are retained for a longer period in the intestine of the animals, with the highest number obtained 72 and 96 h after, respectively. The passage of seeds through the digestive system of D. virgatus for 24 h and P. stipulacea for 72 h, promoted the overcoming of dormancy, reaching Ger values of 66.7 and 35.7%, respectively. The Ger of M. tenuiflora seeds as well as the Ger and survival of M. caesalpiniifolia seeds decreased after passing through the digestive system. The recovery of seeds from the four species indicates that goats are efficient seed dispersers in Caatinga areas.