Resumo

GALINDO-BLANCO, Juana L et al. Ecosystem with Leucaena leucocephala: its effect on the rumen microbial population in fattening bulls. Pastos y Forrajes [online]. 2018, vol.41, n.2, pp. 138-144. ISSN 2078-8452.

A trial was conducted in order to evaluate the effect of Leucaena leucocephala cv. Peru on the rumen microbial population of Zebu crossbred bulls, in the two stages of the fattening cycle. The system, integrated by five strips of grasses associated with L. leucocephala and five without association, consecutively alternated in 25 ha, allowed the fattening of 80 animals, from which eight were used for the microbiological studies. The samplings of rumen liquid were made bimonthly (February-March, April-May, June-July) and four-monthly (August-November). The cellulolytic bacteria reached values between 15,94 and 46,13 106 CFU.mL^-1 when the bulls grazed L. leucocephala associated with grasses. The highest population of rumen cellulolytic fungi was found in the rumen of animals in the system with L. leucocephala, in the August-November samplings. The concentration of rumen ammonia had values of 8,76 and 24,09 mmol.L^-1 in the system with grasses and the one of L. leucocephala associated with grasses, respectively (p < 0,001). The pH in rumen was significantly higher, the population of total viable bacteria was 2,9 times higher and the protozoans decreased when L. leucocephala participated in the ration. It is concluded that the system with L. leucocephala associated with grasses is advantageous, because it propitiates increases in the populations of total viable bacteria and fiber-degrading microorganisms; this, along with the depressing effect of protozoans, guarantees a favorable ecological environment for rumen cellulolysis, which would contribute in a sustained way to the productive increase of the animal husbandry system.

Palavras-chave : bacterium; metabolites; protozoans.

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