Effect of the method and the period of oil extraction on chemical composition of olive cake in northern of Morocco

In the northern of Morocco, goat population is the most dominant. His diet is based on forest rangelands. Therefore, it is necessary to diversify and improve its feed calendar. Olive cake is by-product of oil extraction that widely available in the region with important production. It can be a feed resource of ruminant. This resource is produced by three methods and for limited period. This work aims to determine the effect of different oil extraction method and period on the chemical composition of olive cake in northern of Morocco. Twenty-seven samples of olive cake were collected from 3 mills by each extraction method (mechanical pressure, centrifugation 2 and 3 phases) during three periods (November, December and January). The chemical composition (dry matter, fat, mineral matter, crude protein and fibers) of the collected samples was determined by AOAC methods (1997). The extraction method had a significant effect on all parameters of the chemical composition with the exception of the fat and crude protein (P<0.05). The olive cake obtained by centrifugation 2 phases method had lower dry matter and fibers. The period had no effect on chemical composition, which eases the introduction of olive cake in the diet of ruminants. The olive cake of 2 phases is the most suitable for feed but has a reduced shelf life, which requires the development of a suitable conservation mode.