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Effect of Bacillus subtilis and its delivery route on hatch and growth performance, blood biochemistry, and immune status of broiler chickens

2022 CPRF,Nutrition
As the poultry industry recedes from the use of antibiotic growth promoters (AGP), there is a need to evaluate possible alternatives and the delivery method that maximizes their effectiveness. This study evaluated the effect of a probiotics (Bacillus subtilis fermentation extract) and its delivery route (in-feed or in ovo) on hatch and growth performance, blood biochemistry, and immune status of broiler chickens. A total of 1,860 Cobb 500 hatching eggs were incubated for 21 days. On d 12 of incubation, viable eggs were randomly allotted to 4 groups: the non-injected, in ovo saline (S), in ovo B. subtilis 1 (P1), and in ovo B. subtilis 2 (P2). On d 18 of incubation, S, P1, and P2 groups received 0.2 mL saline diluent, 10 × 106, and 20 × 106 CFU of the bacterium/0.2 mL saline diluent via the amnion, respectively. At hatch, chicks were re-allotted to 5 new treatment groups: P1, P2, 0.005% in-feed B. subtilis extract (F), 55 mg/kg in-feed bacitracin methylene disalicylate (BMD), and corn-wheat-soybean diet negative control (NC) in 9 replicate pens (22 birds/pen) and raised for 35 d. Hatch parameters were assessed on d 0 and body weight and feed intake (FI) were measured weekly. On d 25, 1 bird/cage was euthanized, and immune organs weighed. Blood samples were collected for plasma biochemistry and serum immunoglobulins (IgG, IgM) analysis. Data were analyzed in a randomized complete block design using the generalized linear model. Treatments recorded no effect on chick weight, chick length, and hatchability. Contrastingly, birds in treatments F and P2 had reduced (P<0.050) FI at week 5, compared to the NC treatment. However, no change in average body weight gain (ABG) and feed conversion ratio (FCR) were observed during the same period. At the end of the trial (d 35), while BMD treatment showed a tendency (P=0.087) to increase average FI compared to the NC treatment, ABG and FCR were similar for all treatment groups. Plasma electrolytes minerals (sodium and chloride) levels were increased (P<0.05) by the BMD treatment compared to the NC treatment. Other treatment groups recorded intermediate values of these electrolyte minerals. While the relative weights of the bursa and spleen were not affected by treatments, all probiotics treatments (irrespective of route and dose) reduced (P<0.001) the levels of serum IgG compared to the NC treatment. However, the greatest reduction (99%) was observed in the P2 treatment. This study suggests that probiotics (especially in ovo delivered) might offer better immunological protection to broiler chickens by neutralizing pathogenic organisms that could lead to the production of natural antibodies, without negatively affecting hatch and growth performance.
Tags :
broilers,growth promoters,probiotics
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