Influence of antibiotics, glyphosate and a Bacillus sp. strain on productivity performance and gene expression in cross Ross 308 broiler chickens (Gallus gallus L.)

The combination of antibiotics and pesticide residues can compromise the therapeutic and production benefits of antibiotics in the poultry industry. These effects may be reflected in changes of gene expression. The present work, for the first time, shows that the stimulation of poultry meat productivity with veterinary antibiotics enrofloxacin and colistin is probably associated with the induced expression of MYOG gene which is known to promote the development and differentiation of muscles, genes of antimicrobial ( Gal9 , Gal10 ) and antiviral ( IRF7 ) protection, and pro-inflammatory genes IL6 , IL8 and PTGS2 . In addition, it was shown for the first time that glyphosate suppresses the expression of antimicrobial and antiviral genes in broilers of the Ross 308 cross. The aim of the study was to evaluate the change in the expression spectrum of key genes in broiler fed antibiotics, glyphosate and a biodestructor strain. The experiments were carried out on broilers of the Ross 308 cross from 1 to 35 days of age (the vivarium of BIOTROF+ LLC, 2022). The broilers were divided into 4 groups of 40 birds each. Group I (control) was fed a diet without additives, group II received a diet with the addition of veterinary antibiotics enrofloxacin and colistin; group III experienced dietary antibiotics and glyphosate; group IV received dietary antibiotics, glyphosate and a strain of the microorganism-biodestructor Bacillus sp. GL-8. Glyphosate content was measured by ELISA using a STAT FAX 303+ analyzer (Awareness Technology, LLC, USA) and a Glyphosate ELISA Microtiter Plate test system (Abraxis, USA). Reverse transcription quantitative PCR was performed to evaluate gene expression of the caecum and pectoral muscle tissues. Total RNA was isolated from samples using the Aurum™ Total RNA mini kit (Bio-Rad, Hercules, USA). Specific primers were selected for immunity genes IL6 (interleukin 6), IL8 (interleukin 8), IRF7 (interferon regulatory factor7), PTGS2 (prostaglandin-endoperoxide synthase), AvBD9 ( Gal9 ) (β-defensin 9), AvBD10 ( Gal10 ) (β-биотро,bjnhdefensin 10). For productivity genes, LGF-I (insulin-like growth factor 1), MYOG (myogenin), MYOZ2 (myosenin) and GSTA3 associated with resistance to toxic and medicinal substances were tested. Amplification reactions were carried out using SsoAdvanced™ Universal SYBR® Green Supermix (Bio-Rad, USA) using a DTlight amplifier (DNA-Technology, Russia). The body weight of broilers was assessed at 7, 14, 21, 28 and 35 days of age. Mathematical and statistical data processing was performed using multivariate analysis of variance in Microsoft Excel XP/2003, R-Studio (Version 1.1.453) (https://rstudio.com). The results showed a 4.8-23.3 %-stimulated productivity (p £ 0.05) of broilers from 14 days of life until the end of the experiment due to dietary antibiotics (group II vs. group I). At the end of the experiment, a negative effect of glyphosate on broiler productivity occurred (group III vs. group II, p £ 0.05). In broilers of groups II and IV, the expression of MYOG gene was 2.0 and 2.1 times higher than in group I (p £ 0.05). In the group fed glyphosate combined with antibiotics without a biodestructor strain added (group III), no activation of the MYOG gene expression occurred compared to group I (р ˃ 0.05), which indicates a negative effect of glyphosate on the expression of productivity genes. Glyphosate (group III) also acted as a suppressor of the antimicrobial and antiviral genes Gal9 , Gal10 and IRF7 as compared to group II (p £ 0.05). The dietary biodestructor strain co-fed with glyphosate and antibiotics (group IV) provided an increase in Gal9 expression compared to group III (p £ 0.05). There was a tendency for a sharp increase in the expression of pro-inflammatory genes IL6 , IL8 and PTGS2 (by 4.6, 11.2 and 6.6 times, respectively) in group II fed antibiotics vs. control group I (p £ 0.05). Our findings once again confirms the effect of antibiotics on immune processes. For GSTA3 gene associated with resistance to toxic and medicinal substances, it was shown that the introduction of antibiotics into feeds had some stimulating effect on the level of GSTA3 gene expression in the caeca tissues of broilers (group II vs. group I, p £ 0.05). Thus, the mechanism providing positive effects of antibiotics on productivity performance is probably partly due to the fact that they act as inducers of a set of important genes. Glyphosates fed in an amount corresponding to 1MPC reduced the stimulating effect of antibiotics. Glyphosates act, among other things, through the disruption of the activity of some key bird genes. The positive dynamics of the expression of various genes, including those involved in antimicrobial and antiviral defense, under the action of a biodestructor strain indicates the prospects for using probiotics as a means of smoothing out physiological imbalances caused by drugs and food contamination with toxic substances.