Does shifting from a commercial to a natural diet affect the nutritional status of hand-reared grey partridges Perdix perdix?
Two feeding trials (January to April 1996 and 1997) using a total of 54 hand-reared grey partridges were performed in Finland to study the effect of a change from a commercial pelleted diet to a natural diet (barley, oats and weed seeds) on body mass, food consumption, metabolised energy coefficient, gut morphology and some blood metabolites. The abrupt change in the diet which takes place when hand-reared birds are released into the wild was simulated. Controls continued to be given the pelleted diet throughout the trial. Group body mass decreased significantly after the change in diet. However within 1 week, body mass started to increase again, but it stabilised at a lower level than in control birds (P<0.05). Compared with controls, birds in the test group consumed more food (fresh weight) during the feeding trial (P<0.001) and produced more excreta during the 2nd, 4th and 5th week of the feeding trial (P<0.001). Gross energy intake, amount of metabolised energy and metabolised energy coefficient decreased and excretory energy content increased during the feeding trial. No differences were seen in the analysed blood metabolites. Gizzards of the test birds were heavier than those of the control birds (P=0.01). It is concluded that a period of 6 weeks may be inadequate for partridges to get totally adapted to a new diet.