Faecal calprotectin and IgA have been suggested as non-invasive markers of gut health. Faecal calprotectin is a marker of intestinal inflammation in adults, whereas IgA has been suggested as a marker of intestinal immunity. The purpose of the present study was to evaluate the effect of gestation, lactation and age on faecal concentrations of these biomarkers. Thirty puppies, nineteen pregnant or lactating bitches and eighty-nine healthy control adult dogs were included in the study. Faeces were collected from the fourth week of gestation until the eighth week of lactation in pregnant and lactating bitches, and between 4 and 9 weeks of age in puppies. Faeces from the eighty-nine healthy control adult dogs were also collected. Faecal calprotectin and IgA concentrations were measured. Faecal calprotectin concentrations in control dogs were significantly lower than faecal calprotectin concentrations in puppies between 4 and 6 weeks of age (P < 0·001) or between 7 and 9 weeks of age (P = 0·004). Puppies between 4 and 6 weeks of age had significantly higher faecal IgA concentrations compared with puppies between 7 and 9 weeks of age (P = 0·001). Bitches during their second month of lactation had significantly lower faecal IgA concentrations compared with their first month of lactation (P = 0·049). Faecal calprotectin and IgA have been suggested as non-invasive and easily measured biomarkers of gut health in adults. However, the present study underlines that faecal IgA and calprotectin concentrations vary markedly depending of physiologic factors such as gestation, lactation and age. These factors need to be considered when these faecal biomarkers are used for evaluation of intestinal immunity or inflammation.

Intestinal bacterial colonisation in pre-term infants is delayed compared with full-term infants, leading to an increased risk of gastrointestinal disease. Modulation of colonisation through dietary supplementation with probiotics or prebiotics could decrease such a risk. The present study evaluated clinical tolerance, the effects on gut microbiota, and inflammatory and immunological mucosal responses to an infant formula adapted for pre-term infants that included in its manufacturing process a fermentation step with two probiotic strains, Bifidobacterium breve C50 and Streptococcus thermophilus 065, inactivated by heat at the end of the process. A total of fifty-eight infants (gestational age: 30–35 weeks), fed either the fermented pre-term formula or a standard pre-term formula, were followed up during their hospital stay. Clinical tolerance, faecal microbiota using a culture and a culture-independent method (temporal temperature gel electrophoresis), faecal calprotectin and secretory IgA were analysed weekly. No difference was observed regarding anthropometric data and digestive tolerance, except for abdominal distension, the incidence of which was lower in infants fed the fermented formula for 2 weeks. Bacterial colonisation was not modified by the type of feeding, particularly for bifidobacteria. Faecal calprotectin was significantly lower in infants fed the fermented formula for 2 weeks, and secretory IgA increased with both mother's milk and the fermented formula. The fermented formula was well tolerated and did not significantly modulate the bacterial colonisation but had benefits on inflammatory and immune markers, which might be related to some features of gastrointestinal tolerance.