Effects of dietary non-starch polysaccharides on establishment and fecundity of Heterakis gallinarum in grower layers

Abstract

It was hypothesized that the establishment and fecundity of Histomonas meleagridis free Heterakis gallinarum may be affected by dietary non-starch polysaccharides (NSPs). One-day-old female layer chicks (N=670) were fed ad libitum for 11wk one of the following diets in a three-times repeated experiment: basal diet (CON), basal diet plus pea bran rich in insoluble NSP (I-NSP), basal diet plus chicory root meal as a source of inulin rich soluble NSP (S-NSP). At the end of wk three, each feeding group was subdivided into an uninfected and an infected group of birds each being inoculated with a placebo or with 200 H. meleagridis free eggs of H. gallinarum. The birds were slaughtered 8wk post infection and their worm burdens, the nematode egg excretion, caeca sizes and weights as well as intracaecal pH and volatile fatty acid (VFA) concentrations were determined. The NSP supplemented diets and also infection led to reduced body weights (BWs) of birds and impaired the feed conversion rate (P<0.001). The NSP supplemented diets increased average length of caecum (P<0.001) with S-NSP exerting a stronger effect than I-NSP (P<0.05). Full caeca weight was increased by S-NSP (P<0.001). Feeding S-NSP lowered intracaecal pH and molar proportion of acetate and increased that of butyrate compared to CON and I-NSP (P<0.001). Caecal pool of VFA was increased with S-NSP (P<0.001). The NSP-diets elevated incidence of infection (P<0.01), average number of larvae (P<0.009) and total worm burden (P<0.001) compared to CON. The daily amount of faeces increased in NSP-fed birds (P<0.001). Number of eggs per gram of faeces (EPG), number of eggs excreted per worm population of a bird within 24h (EPD) and female worm fecundity (EPD/female worm) were elevated after feeding S-NSP (P≤0.002), whereas I-NSP led to lower EPG/female worm (P<0.05). The EPD increased in the sequence of CON<I-NSP<S-NSP (P<0.001). It is concluded that the pea bran and chicory root meal used as sources of insoluble and soluble dietary NSPs, respectively, provided favourable conditions for the establishment of H. gallinarum in grower layers. Chicory root meal additionally enhanced fecundity of the nematode. Therefore, the two natural sources of insoluble and soluble NSPs offer no potential as protecting agents against H. gallinarum infections in chicken.