The effects of 1-h soaking, fermentation and phytase supplementation of a pig diet based on wheat and barley on ileal and total tract apparent digestibility in growing pigs fitted with a post valve T-caecum (PVTC)-cannula were studied. Eight animals in a two-period change-over design were used, subjecting four animals to each treatment (dry, soaked, microbial phytase supplemented or fermented diet). Acid insoluble ash was used as an indigestible marker for calculating apparent digestibility coefficients. Fermentation improved (P<0·05) the ileal apparent digestibility coefficients of organic matter (OM), nitrogen and amino acids, while there was no effect of 1-h soaking and phytase supplementation. The total tract apparent digestibility coefficient of OM was also improved by fermentation. The ileal apparent digestibility coefficient of phosphorus (P) was higher for fermentation (P<0·05) than for dry food and 1-h soaking. The total tract apparent digestibility coefficient of P was higher (P<0·05) for treated food (soaked, fermented and supplemented with microbial phytase) compared with dry food. Fermentation improved (P<0·05) the ileal apparent digestibility coefficient of calcium compared with dry and soaked food, and had no effect on the total tract apparent digestibility coefficient of calcium. Food inositol phosphates were affected by treatment (P<0·05), with a reduction of P bound to inositol hexaphosphate (IP6) of 10% in the 1-h soaked food and of 80% in the fermented food. Degradation of IP6in the gastro-intestinal tract of the animals was lower in the fermented food than in the other treatments. The content of neutral-detergent fibre in the food was reduced (P<0·05) in the soaked and fermented food by 4% and 14%, respectively, compared with the dry food. In conclusion, fermentation of food can improve digestibility of OM, degrade IP6and increase ileal digestibility of phosphorus, nitrogen and amino acids.

The diversity of populations of yeast and lactic acid bacteria (LAB) in pig feeds fermented at 10, 15, or 20°C was characterized by rRNA gene sequencing of isolates. The feeds consisted of a cereal grain mix blended with wet wheat distillers' grains (WWDG feed), whey (W feed), or tap water (WAT feed). Fermentation proceeded for 5 days without disturbance, followed by 14 days of daily simulated feed outtakes, in which 80% of the contents were replaced with fresh feed mixtures. In WWDG feed, Pichia galeiformis became the dominant yeast species, independent of the fermentation temperature and feed change. The LAB population was dominated by Pediococcus pentosaceus at the start of the fermentation period. After 3 days, the Lactobacillus plantarum population started to increase in feeds at all temperatures. The diversity of LAB increased after the addition of fresh feed components. In W feed, Kluyveromyces marxianus dominated, but after the feed change, the population diversity increased. With increasing fermentation temperatures, there was a shift toward Pichia membranifaciens as the dominant species. L. plantarum was the most prevalent LAB in W feed. The WAT feed had a diverse microbial flora, and the yeast population changed throughout the whole fermentation period. Pichia anomala was the most prevalent yeast species, with increasing occurrence at higher fermentation temperatures. Pediococcus pentosaceus was the most prevalent LAB, but after the feed change, L. plantarum started to proliferate. The present study demonstrates that the species composition in fermented pig feed may vary considerably, even if viable cell counts indicate stable microbial populations.

Six 8-week-old Sprague-Dawley rats were studied for 9 days divided into three periods of 3 days each: before transferral to metabolism cages, during metabolic cage housing and after return to their home cages. Faeces were collected daily when the animals were housed in their home cages and every 6 h when the animals were housed in metabolic cages during which time urine was also collected every 6 h. The rate of weight gain was slightly reduced during the 3 days in metabolic cages and the animals produced significantly larger amounts of faeces when housed in metabolic cages than when housed in their home cages. The total faecal excretion of corticosterone (nanograms excreted per hour per kilogram body weight) and immunoglobulin A (IgA) (milligrams excreted per hour per kg body weight) quantified by enzyme-linked immunosorbent assays (ELISAs) exhibited a clear diurnal rhythm in the metabolic cage. Urinary excretions of corticosterone and IgA also followed a clear diurnal cycle. The mean daily amounts of corticosterone excreted were not significantly affected by cage change and by housing in metabolic cages. However, the excretion of faecal IgA was significantly reduced during the 3 days after the period in metabolic cages. Taken together the results indicate that metabolic cage housing is mildly stressful for young adult male rats.

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