| Abstract: | Diurnal variation in faecal excretion of dietary chromium (Cr) was studied in this experiment in mature swine. Five gestating sows weighing between 225 and 250 kg were fed a corn/soya bean meal diet containing 14% crude protein, NRC recommended amounts of vitamins and minerals with a Ca: P ratio of 1.3:1. Chromic oxide was added (0.1% w/w) to the test diet, and ferric oxide was added (0.5% w/w) to the pre-test and post-test diets as dietary markers. Sows received 0.9 kg of the diet twice daily for 8 days. Total faeces from the test diet were collected and a sample of approximately 150 g of morning samples for days 6 to 9 of the experiment was separated. Faecal recovery of dietary Cr was calculated from the total collection and the samples of the 4-day period. It was found that faecal concentration of the Cr varied between days (P < 0.05) and between times of the day (P < 0.05); true equilibrium of Cr excretion was never reached. Diurnal variation in faecal excretion of dietary Cr was shown to exist; Cr concentration was higher in the late morning samples than in the morning samples (P < 0.05). Total faecal recovery of dietary Cr was 93.27%, whereas a greater (P < 0.05) value was obtained by morning sampling (118.76%). A portion of the dietary Cr (6.73%) was retained in the gastrointestinal tract even after 2 days of Cr withdrawal from the diet. |
