Estimating pasture intake and nutrient digestibility of growing pigs fed a concentrate-forage diet by n-alkane and acid-insoluble ash markers.

A study was carried out to determine voluntary forage intake and nutrient digestibility in growing pigs fed a mixed forage and concentrate diet. Twenty-five 8-week-old Large White × Landrace crossbred male pigs (27 ± 3.8 kg) were blocked by weight into five groups, and each was randomly allocated to four indoor treatments (A, B, C, and D), which received 100, 90, 80, and 70 % of ad lib concentrated intake and an outdoor treatment (E) that received 80 % of ad lib concentrate. Indoor treatments were either fed the concentrate only (A) or also received freshly cut Kikuyu grass (Pennissetum clandestinum) ad libitum (B, C, and D), while pigs on treatment E were reared outdoors in Kikuyu grass paddocks. There was a significant correlation between the amount of concentrate offered and its intake (P < 0.01). The intake of Kikuyu was similar among treatments (P > 0.05). Mean acid-insoluble ash digestibility estimates of organic and dry matter were superior to C(32) estimates (P < 0.05). Kikuyu intake was higher (P < 0.05) than the estimated intake by 0.076 ± 0.03 kg. It was concluded that Kikuyu intake was not affected by the reduction of the concentrate allowance, and this should be taken into consideration when feeding pigs on pasture.