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 24 h (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.