Intrinsic factors of acorns that influence the efficiency of their consumption by Iberian pigs

Abstract

This paper deals with the efficiency of Iberian pigs when shelling acorns ( Quercus ilex fruits) during the free ranging fattening period in the dehesa. The amount of kernel wasted per acorn (18.9 ± 1.2%) presents a high degree of variation influenced by differences in the morphology and size of the acorns. A positive correlation is observed between the weight of the waste kernel and the weight of the whole acorn, and the diameter. However, the percentage of waste correlates negatively with the weight of the kernel and its DM percentage, with the ratio kernel weight/shell weight, and with the percentage of kernel. On the other hand, the percentage of kernel wasted, correlates positively with the percentage of kernel. Oppositely to the traditional knowledge and opinion of farmers, it has been found that the bitterness of the kernel, assessed sensorially by humans, does not influence the amount of kernel wasted. The results indicate that it is possible to make predictions about wastage based on two simple linear regression models: dry kernel wasted = 0.404 × fresh shell weight ( R 2 = 0.898; P = 0.000) and percentage of fresh kernel wasted = 0.893 × percentage of fresh shell ( R 2 = 0.875; P = 0.000). It would be necessary to consider the kernel wastage in acorn conversion rate calculations. Also in the processes of acorn selection for tree repopulation in dehesas for pig finishing it would be convenient to consider the correlations between the characteristics of the acorns and the amount of kernel waste, using the regression models defined.