Gastrointestinal response of laying hens to graded dietary inclusion levels of yellow lupine seeds

Abstract

This study investigated differences in the architecture of intestinal mucosa, digestive and fermentation processes in laying hens fed diets in which soybean meal (SBM) was replaced with increasing levels of yellow lupine seeds (YL) for 16 weeks. Two hundred twenty-four Lohmann Brown hens aged 32 weeks were placed in battery cages and were assigned to four dietary treatments (56 replicates in each, 1 hen per replicate). Diets containing 100, 200 or 300 g/kg YL (YL100, YL200 and YL300, respectively) were compared with a control soybean-wheat-based diet (YL0). Diets containing YL did not negatively affect the key variables of hens performance. Increasing dietary inclusion levels of YL caused a linear increase in duodenal mucosa thickness (P = 0.046), crypt depth (P = 0.016) and villus height (P = 0.066). In the jejunum, a quadratic effect of YL inclusion was noted for mucosa thickness (P = 0.021) and crypt depth (P = 0.007), with the lowest values in groups YL100 and YL200. The dietary YL significantly decreased the weight of the small intestine with digesta vs. YL0. Dietary treatments had no effect on the hydration, pH and viscosity of the small intestinal contents or the weight of cecal tissue and contents. Dietary YL treatments linearly increased the dry matter content of cecal digesta (P = 0.029), and decreased cecal pH (P = 0.028) and ammonia concentrations (P = 0.001). Dietary YL led to a linear increase in the activity of microbial enzymes, including α-glucosidase, α- and β-galactosidase, α-arabinopyranosidase and β-xylosidase (all P < 0.001), whereas no differences were found in the activity of β-glucosidase and β-glucuronidase. Increasing dietary inclusion levels of YL linearly decreased the concentrations of total short-chain fatty acids (SCFAs) in the small intestinal digesta (P = 0.040), and increased SCFA levels in the cecal contents (P = 0.043). Dietary treatments had no influence on the apparent digestibility coefficients of nutrients as well as nitrogen retention. No significant differences were observed in the majority of the analyzed blood biochemical and enzymatic parameters. Dietary YL, despite its higher content of non-starch polysaccharides (NSPs) and raffinose family oligosaccharides (RFOs) in comparison with the SBM-based diet, can be regarded as a valuable dietary component for laying hens due to the fact that it induces positive changes in the fermentation processes in the ceca.