Counts of ruminal fibrolytic bacteria in Creole goats of Mendoza, Argentina.

GRILLI, D.; PAEZ, S.; EGEA, V.; CERON, M.; COBOS, E.; ALLEGRETTI, L.

San luis

Jornada; XXVII Reunión Científica Anual de la Sociedad de Biología de Cuyo"; 2009

Sociedad de Biología de Cuyo-Universidad Nacional de San Luis

In Lavalle, Mendoza, goats consume a highproportion of shrub species, which represent a large supply of fiber. Thedigestibility of dry matter and fiber (cellulose, hemicellulose and lignin) ofgoat breeds adapted to arid areas is higher than that of other races anddomestic ruminants. A high efficiency in use of fiber may be due to a largeconcentration of fibrolytic bacteria on food particles present in the rumen.The aim of this study was to quantify the ruminal fibrolytic microbiota inCreole goats in two seasons. Rumen samples were taken from a cannulated goatgrazing on natural grassland in the summer (wet season) and winter (dry season).Cellulolytic, hemicellulolytic and pectinolytic bacteria were quantified bymost probable number method. Bacterial counts were submitted to logarithmictransformation before performing ANOVA (Tukey test). Concentrations of cellulolytic,hemicellulolytic and pectinolytic bacteria were significantly higher in summer(0.08325x109, 7 x1010 and 7x1010 bacteria.mL-1, respectively) than in winter(0.0035x109, 0.01725x1010 and 0.585x1010 bacteria mL-1, respectively). Ligninaffects fibrolytic bacteria count, because it inhibits the hydrolysis andutilization of carbohydrates by bacteria in the rumen. Higher counts observed duringsummer may arise because the goats selected shoots of shrubs with lower lignin contentin the wet season. Further work should assess the relationship between thenutritional composition of diet and fibrolytic rumen microbiota.