EFFECTS OF GENOTYPE AND SEX ON THE FEED-INTAKE PATTERN OF GROUP-HOUSED GROWING PIGS

Individual feed intake patterns were recorded for 273 Dutch Landrace (DL) and 132 Great Yorkshire (GY) pigs during five batches. The pigs were grouped in pens of 8 within sex and breed. Freed intake was ad libitum. Weight of the test period varied from 2 5 to 3 5 kg at the beginning and the test ended when an average live weight per pen of 100 kg was reached. Daily weight gain (WG), ultrasonic backfat thickness (BT), feed conversion ratio (FC) and lean percentage (IVO, HGP) were measured individually. Feed intake pattern was described by daily feed intake (FID), daily eating time, frequency of eating and meal size. Performance traits and feed intake pattern traits were significantly influenced by breed (P<0.01 and P<0.05, respectively), with exception of daily feed intake (P>0.05). GY pip had a better WG, FC, IVO and HGP than DL pigs. GY ate more frequently, in smaller meals and less daily eating time compared with DL, at almost equal FID. Boars had significantly higher daily gain and better feed conversion ratio (P<0.01) than gilts. Feed intake per visit to the feed hopper was significantly higher for boars, whereas frequency of eating (number of visits, number of meals) was lower (P<0.05). Heritability estimates for feed intake traits were low to moderate. It is concluded that the feed intake pattern is partially under genetic control, although standard errors were large. Number of visits and meals per day and feed intake per visit and per meal had moderate heritabilities.