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

Abstract

This feeding study investigated the hypothesis that over-processing of meat and bone meal (MBM) would impair the performance, gut health and ileal digestibility of nutrients in birds challenged with necrotic enteritis (NE). The effect of phytase (500 vs. 5,000 FTU/kg) was also examined using manufacturers recommended matrix values for 500 FTU for both levels. Ross 308 male broilers ( n = 768) were assigned to 8 diets, with 6 replicate pens per diet and 16 birds per replicate pen using a randomized design with a factorial arrangement of treatments. Factors were NE challenge (no or yes), MBM (as received or over-processed), and phytase level (500 or 5,000 FTU/kg). Half of the birds were challenged with 5,000 oocysts of field strains of Eimeria acervulina and Eimeria brunetti , and 2,500 oocysts of Eimeria maxima on d 9 and 10 8 CFU/mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15 post-hatch. Challenge × MBM interactions were detected for weight gain (WG), feed conversion ratio (FCR) and feed intake (FI) at d 14, 21 and 28, showing that challenged birds fed over-processed MBM had decreased WG ( P < 0.05) and FI ( P < 0.05) at d 14, increased FCR ( P < 0.05) at d 21 and decreased WG ( P < 0.05) and FI ( P > 0.05) at d 28. Birds fed low phytase had increased livability ( P < 0.05) at d 42. The challenge increased the prevalence and severity of NE induced lesions in the jejunum ( P < 0.05) and ileum ( P < 0.05). The birds fed over-processed MBM had decreased pH in the jejunum ( P < 0.05) and ileum ( P < 0.05) at d 16. High phytase increased apparent ileal digestibility (AID) of Ca ( P < 0.05) and P ( P < 0.05), and over-processed MBM increased AID of carbon (C; P < 0.05) and Ca ( P < 0.05) at d 29. The challenge increased the caecal counts of Lactobacillus spp. ( P < 0.05) and C. perfringens ( P < 0.05) at d 16. The results indicated that supplementation of diets with high phytase reduces the negative impact on performance from over-processed MBM during NE as a result of increased nutrient digestibility.

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 2. Inositol phosphate esters hydrolysis, intestinal permeability, hematology, jejunal gene expression and intestinal morphology

“…Rather, they were downregulated by the challenge. This observation in the challenge group might explain the lower nutrient absorption detected in this study ( Zanu et al, 2020a ) and in other studies ( Guo et al., 2013 , Rochell et al., 2016a ). Nonetheless, over-processing of MBM tended to upregulate CaSR in unchallenged birds fed low phytase.…”

“…The slower the turnover of tissues, the better for the growth of the chicken. This is because the maintenance requirement is reduced, thus improving the feed conversion ratio of the chicken as previously reported ( Zanu et al, 2020a ) in unchallenged birds. However, during incidences of enteric diseases such as NE the morphology of the intestine is impaired and the nutrient absorptive and enzyme secretory organs are reduced.…”

“…Also worthy of note is the fact that the hydrolysis of IP5 and IP6 was more pronounced in the challenged birds, particularly when low phytase was present. The higher degradation in the challenged birds might have been necessitated by either the lower pH recorded in the ileum at d 29 or lower feed (phytate) intake at d 28 as reported ( Zanu et al, 2020a ). The lower the pH, the less negatively charged IP6 becomes, and its ability to chelate positively charged ions is reduced ( Bedford and Rousseau, 2017 ).…”

“…The higher destruction of the IP in the challenged birds also translated into a higher inositol production. However, a buildup of calcium and amino acids in the lower gut (during the severe stages of the NE infection) might feed pathogenic enteric bacteria such as C. perfringens and induce NE, unless birds are protected with antimicrobials ( Zanu et al, 2020a ). It is worth noting that the determination of phytate esters was conducted at d 29 (14 days post-challenge) when the challenge effect might have waned.…”

“…These metabolites increase the pH in the gut and favor the activity of C. perfringens. A recent study has confirmed that MBM increases the proliferation of C. perfringens and decreases the performance of broilers fed high phytase without antibiotics ( Zanu et al, 2020a ). The use of exogenous phytase at higher levels than normally practiced can facilitate the reduction or removal of MBM because phytase releases P and increases amino acid (AA) digestibility of plant proteins.…”