Necrotic enteritis (NE) is a poultry disease of global concern mainly due to reduced growth, increased mortality, and increased veterinary and management costs associated with it (Wade and Keyburn, 2015). Clostridium perfringens, a spore-forming gram-positive bacterium, is considered to be the causative agent of NE in chickens. In the past, the common remedy to ameliorate the negative effects of NE was an addition of antibiotic growth promoters (AGP) in feed. However, with AGP phasing out worldwide, there have been efforts to find alternatives to improve intestinal health. In this regard, special attention has been paid to short and medium chains fatty acids due to their proven benefits on intestinal health and performance (Zentek et al., 2012).
A study was conducted using 816 as-hatched 1-d-old chicks (Cobb 500) to evaluate the effects of a buffered formic acid (Amasil NA™) and a synergic combination of 1-monoglycerides of short and medium chain fatty acids (Balangut™ LS P). These additives were added to wheat-soy basal diet singly or in combination at various rates and assigned to six dietary treatments with eight replicates of 17 birds per pen unchallenged negative control (NC) with no additive (T1); and five challenged groups orally inoculated with 1 mL Eimeria vaccine on d 9 and C. perfringens on d 14 with: no additives as positive controls (PC, T2); buffered formic acid (0.3% throughout all the phases, T3); 1-monoglycerides (0.5%, 0.3%, and 0.2% in starter, grower and finisher phases respectively, T4); a combination of buffered formic acid and 1-monoglycerides (0.3% + 0.3%, 0.2% + 0.2%, and 0.2% + 0.15% in starter, grower and finisher phases respectively, T5); and Zn bacitracin (0.05 % throughout all the phases, T6). Feed refusal and body weight of birds were measured in each pen every week to calculate performance parameters until d 35. On d 16, four birds (two males and two females previously feather sexed and marked) were randomly selected from each pen and euthanised for scoring NE lesions in the small intestine.
The results confirmed the presence of sub-clinical NE as observed by lower feed intake (P < 0.01) and weight gain (P < 0.01) in the challenged PC compared to the unchallenged NC. While the birds in NC had no lesions in the gut (lesion score 0), those in PC had lesions in the jejunum and ileum sections of the intestine which were significantly different from the NC (P < 0.01). During 9-21 d, challenge increased FCR by 8 points (P < 0.01) but the group supplemented with a combination of buffered formic acid and 1-monoglycerides had similar FCR to the NC (P > 0.05) and 5 points less FCR than the PC. During 21-35 d, there were no differences (P > 0.05) in feed intake and weight gain between NC and PC but the challenged groups with additives reduced FCR by 6-7 points (P < 0.01) compared to NC. During 0-35 d, the additives had no effect on feed intake and weight gain in the challenged groups, but FCR tended to be lowered (P=0.08) and the lowest FCR was observed in the group fed the combination of buffered formic acid and 1-monoglycerides. These results suggest that, under NE challenge, the dietary supplementation of buffered formic acid and 1-monoglycerides at suggested dose rates may improve the efficiency of feed utilization in broilers possibly due to improved intestinal health.
Presented at the 31th Annual Australian Poultry Science Symposium 2020. For information on the next edition, click here.