Effects of particle size and extrusion of maize and sorghum on ileal digestibility and growth performance in pigs weaned at 14 and 21 days of age

Two experiments were conducted to compare apparent ileal digestibilities an d growth performance in pigs fed ground and extruded maize and sorghum. In Experiment 1, for digestibility, 24 early-weaned pigs (14 d old and 3.2 kg BW; EW) were given a terminal ileum exteriorization, and another 24 convent ionally-weaned (CW) piglets (21 d old and 6.3 kg BW) were fitted with simpl e T-cannulae. An additional 8 piglets were employed for correction of endog enous amino acid excretions. Dietary treatments consisted of six differentl y processed maize and sorghum diets: 1. maize 900 mum, 2. maize 400 mum, 3 extruded maize, 4. sorghum 900 mum, 5. sorghum 400 mum, and 6. extruded sor ghum. In Experiment 2, 150 piglets (21 d of age and 6.4 kg BW) were allotte d to the same dietary treatments and used in a 33-d feeding trial. Reduced particle sizes of the grains from 900 to 400 mum tended to improve the apparent ileal digestibilities (BID) of Thr, Val, Leu, and Lys in maize and Thr, Val, and Leu in sorghum for EW, but not for CW piglets. The AID o f essential amino acids were higher (P<0.05) in CW than in EW piglets. In t rue ileal digestibilities (TID) of essential amino acids in tested grains, there was a similar trend with the AID of essential amino acids, with the e xception of improvement by 10.7% in EW, and by 8.1% in CW piglets. In this study, however, the ileal digestibility of amino acids was highly (P<3.05) different between weaning ages. The differences were 19.6% in averaged AID, and 174% in TID of essential amino acids, respectively, between weaning ag es. Extrusion of maize and sorghum did not improve the ileal digestibilitie s of amino acids, but the digestibility of Mel in sorghum was improved (P<0 .05) in EW pigs as compared with ground maize and sorghum. Between maize an d sorghum, the ileal digestibility of amino acids was similar. During the o verall period (d 0 to 33), diets with extruded maize and sorghum reduced AD FI (P<0.05) and improved gain/feed (P<0.05) by 3% compared with diets with the ground grains. In conclusion, the ileal digestibility of amino acids in the grains was con siderably affected by weaning ages of piglets, while ileal digestibility of amino acids and growth of pigs was not affected by reductions in particle sizes of maize and sorghum from 900 to 400 mm in complex weaner diets.