ZOFFOUN Gbèliho Alex (2011)
PhD, University of Abomey-Calavi, Benin
The study aims to understand the dynamics of artificial pastures of Kpinnou, Samiondji and Okpara ranches in Bénin through the analysis of the floristic characteristics of plant communities in artificial pastures of the three ranches, the feeding behavior of Girolando cattle on different types of artificial pastures, the effect of grazing intensity on the development of regeneration organ of perennial grasses and pasture productivity in artificial pastures and the analysis of existing interactions between ticks, their bovin hosts and the types of pastures. A total of 99 phytosociological relevés were done according to Braun-Blanquet (1932). The matrix of 231 species identified X 99 relevés was subjected to a DCA (Detrended Correspondence Analysis) and cluster analysis using the software PC-ORD 5. The results revealed 5 individualized plant communities at the three farms as follows: the plant community G1 of Andropon gayanus and Leucaena leucocephala; the plant community G2 of Panicum maximum var. C1; the plant community G3 of Brachiaria ruziziensis and Tephrosia bracteolata; the plant community G4 of Panicum maximum and Vernonia amygdalina; the plant community G5 of Pennisetum purpureum and Sterculia tragacantha. Total species richness of these three farms was 231 species distributed in 49 families. Phanerophytes, therophytes and chamaephytes were the dominant life forms. The chorological distribution of species showed a predominance of wide distribution and continental species. Floristic diversity of herbaceous plant communities under forage crops studied at Kpinnou ranch showed a significant difference between species richness of the plant communities under artificial pastures, natural plant communities and post-cultural formations (p < 0.002 & ddl = 2). Plant communities under artificial pastures were distinct according to Sorensen index (Is < 50 %) which expressed a floristic specialisation of plant cover in accordance with the sowing pastures. The grazing behavior of 16 young Girolando cattle on two types of pasture (Panicum maximum and Panicum maximum var. C1) showed that grazing has held significantly (p < 0.05) 66.7 % of the whole time on Panicum maximum, the rumination 9.9 %, resting 18.1 % and watering 5.3 %. Time proportions spent on the Panicum maximum var. C1 were as follows: grazing 54.3 %, rumination 12.0 %, resting 28.4 % and watering 5.3 %. On average, the bovine ingested significantly (p < 0.05) 109.39 gDM/kg LW0,75 per day on Panicum maximum pasture against 69.67 gDM/kg LW0,75 for Panicum maximum var. C1 pasture. Measurements of tufts density and the recovered surface of stumps and biomass harvesting carried out in 45 plots of Panicum maximum var. C1 and Brachiaria ruziziensis revealed that the average number of tufts per square meter was higher for all plant communities under conditions of overgrazing in non-grazing condition. The recovered surface of stumps and biomass production changed inversely to the density of tufts, depending on age and grazing intensity. The interactions between ticks, their cattle hosts (19 young Girolando dairy cattle) and two types of pasture (Panicum maximum and Panicum maximum var. C1) showed that Amblyomma, Hyalomma, Rhipicephalus and Boophilus were the 4 genuses of ticks identified. The genus Boophilus was most abundant (p
Keywords: Plant community, artificial grassland, plant diversity, carrying capacity, food trays, tillering, density of tufts, ticks, cattle, Benin.