The effect of harvest stage on the potential nutritive value of kermes oak (Quercus coccifera) leaves

Abstract

The aim of the current study was to determine the effect of harvesting stage on the potential nutritive value of oak leaves using the chemical composition and in vitro gas production technique. The oak leaves were harvested in May, July, September and October of 2006 and analysed for their chemical composition. Gas production was recorded before incubation (0) and 3, 6, 12, 24, 48, 72 and 96 h after incubation. The harvest stage had a significant effect on chemical composition and in vitro gas production and the kinetics. The crude protein (CP) and ether extract (EE) content did not differ among the harvest stages (P>0.05). In contrast, the NDF, ADF and ADL contents increased (P<0.01) as the vegetation progressed. The condensed tannin content fluctuated (P<0.001) throughout the study. Generally the gas production of the oak leaves obtained in September and October was higher than those obtained in May and July. The rate of gas production, metabolisable energy (ME) and organic matter digestibility (OMD) values were also highest in October followed by in September, July and May. In conclusion, harvest stage influences the nutritional quality of kermes oak leaves with most of the nutritional parameters determined here being higher in autumn than in summer and spring.