Influence of meat and bone meal, phytase, and antibiotics on broiler chickens challenged with subclinical necrotic enteritis: 1. growth performance, intestinal pH, apparent ileal digestibility, cecal microbiota, and tibial mineralization

Abstract

This study investigated the influence of meat and bone meal ( MBM ), phytase, and antibiotics ( AB ) on the performance, intestinal pH, ileal digestibility, cecal microbiota, and tibial mineralization in Ross 308 broilers challenged with necrotic enteritis ( NE ). A total of 672-day-old male Ross 308 chicks were allocated to 8 treatments with 6 replicate pens, with 14 birds each. The study employed a 2 × 2 × 2 factorial arrangement of treatments: MBM (no or yes), AB (no or yes, zinc bacitracin + salinomycin), and phytase level (500 or 1,500 FTU/kg; both using 500 matrix recommendations). Diets were based on wheat–soybean meal–canola meal. All birds were challenged with Eimeria spp on day 9 and Clostridium perfringens ( C. perfringens ) strain EHE-NE18 on day 14 and day 15. On day 21 (postchallenge), birds fed MBM had reduced weight gain (WG; P < 0.05) relative to without MBM. A 2-way phytase × AB interaction for WG on day 14 ( P < 0.001) and day 21 ( P < 0.001) and feed conversion ratio on day 21 ( P < 0.001) and day 42 ( P < 0.01) indicated positive effects of high phytase on bird performance in the presence of AB. On day 42, a 3-way MBM × phytase × AB interaction ( P < 0.01) was observed for WG, showing high phytase increased WG with AB, relative to the birds without AB in the presence of MBM. A 2-way MBM × phytase interaction ( P < 0.01) was observed for apparent ileal digestibility of Ca and P on day 16, whereby there was a notable reduction in Ca and P digestibility in birds fed MBM-free diets and a low phytase level, but with the high phytase level, Ca and P digestibility was not influenced by MBM. In conclusion, in NE challenged birds, high phytase has a beneficial effect on leg health and mineral utilization to the extent that it can replace MBM and has beneficial effects on bird performance in the presence of AB.

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 1. Performance, intestinal lesions and pH, bacterial counts and apparent ileal digestibility

“…In this study, birds fed over-processed MBM and challenged with NE recorded the lowest pH in the jejunum and ileum at d 16 post-challenge. This observation is contrary to what was detected in the preceding trial in the same facility in which normal MBM (5% inclusion) increased the pH in the ileum and the caeca in challenged birds ( Zanu et al, 2020 ). It suggests that MBM as a Ca source has the potential to increase gut pH ( Angel et al., 2002 ) and that over-processing of the MBM was most likely to have reduced the CaCO 3 content through the process of calcination ( Barros et al., 2009 , Yang et al., 2005 , Silva et al., 2019 ).…”

“…The higher caecal pH in birds fed high phytase and as-received MBM might also suggest that both phytase and as-received MBM released Ca to a certain concentration that elevated the pH. A similar elevation of pH in the ileum and caeca was observed in birds fed MBM (as-received) (5%) and high phytase (1,500 FTU/kg) ( Zanu et al, 2020 ). Therefore, is it not surprising that a possible decrease in CaCO 3 as explained above would have led to a reduction in pH.…”

“…It was established that MBM that predisposes chickens to NE reduces the performance of broilers while the presence of a high phytase dose and antibiotics in diets containing MBM improves performance ( Zanu et al, 2020 ). The present study was designed to test the hypothesis that over-processed MBM by heating under pressure (autoclaving) would decrease the digestibility of the protein and further exacerbate the incidence of NE.…”

“…Nonetheless, 2 other studies that preceded the current study had made a similar observation especially for high Ca digestibility in challenged birds. In one of the studies, feeding MBM (5% inclusion rate) led to a higher Ca digestibility in challenged birds ( Zanu et al, 2020 ). Few studies have reported the digestibility of minerals during NE.…”

Influence of meat and bone meal, phytase, and antibiotics on broiler chickens challenged with subclinical necrotic enteritis: 2. intestinal permeability, organ weights, hematology, intestinal morphology, and jejunal gene expression

“…Details of feed analysis, formulations, and feeding are described in part 1 ( Zanu et al., 2020 ) of this series. A 2 × 2 × 2 factorial arrangement of treatments was used.…”