DIURNAL-VARIATION IN THE COMPOSITION OF ILEAL DIGESTA AND THE ILEAL DIGESTIBILITIES OF NUTRIENTS IN GROWING PIGS

Diurnal variation in the chemical composition of digesta and its effec t on nutrient digestibilities of diets varying in dietary fibre conten t was examined in pigs fitted with a PVTC-cannula at the terminal ileu m. The pigs were fed three times a day (08:04 16:00 and 24:00 h). A ba rley control diet and four barley-based diets containing two levels (1 00 or 200 g kg(-1) diet) of alfalfa meal or white clover meal and Cr2O 3 as an indigestible marker were fed according to a 5 x 5 Latin square design. In each experimental period, digesta were collected for Ih ev ery third hour on each of two separate sampling days, covering in tota l a 24 h period. The concentration of dry matter (DM), crude protein ( CP), ash and chromium (Cr) in the ileal digesta varied in relation to time of feeding. However, the patterns were similar after all three me als (08:00, 16:00 and 24:00 h) and independent of diet. The maximum DM , CP and ash contents were reached 4-5 h post-feeding. The highest (P < 0.05) DM concentration was found in the ileal digesta of pigs fed th e barley control diet. The DM concentration decreased (P < 0.05) as th e inclusion level of alfalfa meal and white clover meal was increased. The lowest DM concentration was found for the highest inclusion level of alfalfa meal. The ileal digestibilities of both organic matter and CP were lower 1-2 h post-feeding compared with those recorded 3-5 h l ater, indicating that the less digestible components of a diet have sh orter transit times. The pooled ileal digestibilities of organic matte r and CP from the three 8 h periods (08:00-16:00 h, 16:00-24:00 h, 24: 00-08:00 h) did not differ (P < 0.05) from each other. Therefore, the estimate of digestibility can be based on digesta samples collected fr om any interval between two consecutive meals. However, care must be t aken to obtain representative samples of digesta between meals.