Effects of the dietary incorporation of olive leaves on growth performance, digestibility, blood parameters and meat quality of growing pigs

BACKGROUND In a preliminary study the oxidative stability and tocopherol content of pork meat were shown to be improved by olive leaf ( OL ) feed supplementation at 50 and 100 g kg −1 . However, growth performance was affected negatively. Therefore the objective of the present study was to assess the influence of OL supplementation at a lower level on feed digestibility, growth performance and meat quality. RESULTS Pigs were fed a basal diet (control), a basal diet with 25 g OL kg −1 ( OL2 .5) or a basal diet with 50 g OL kg −1 ( OL5 ). The incorporation of OL significantly decreased growth rates ( P = 0.010) and backfat thickness ( P = 0.035) and increased feed/gain ratio ( P = 0.032) in the OL5 group. Feed/gain ratio increased more for females ( P = 0.001). The incorporation of OL decreased the crude fat ( P = 0.006) and protein ( P = 0.037) digestibility of both OL diets. Nevertheless, OL was effective in increasing the tocopherol content of meat ( P = 0.009). However, meat from pigs fed the OL diets showed similar conjugated diene content, pH and colour parameters to that from pigs fed the control diet, even after 6 days of storage at 4 °C. CONCLUSION The data indicate that olive leaves may be included in pig diets at 25 g kg −1 in order to improve the tocopherol content of meat without excessively compromising growth performance. © 2014 Society of Chemical Industry