The present experiment was designed to investigate the effect of tamarind polyphenols under different dietary protein diets (soybean and DDGS) on production, physiological and immunological attributes in broilers. Day old chicks (n=280) were randomly distributed into 7 treatment groups with 5 replicates each containing 8 birds. All birds were provided with feed and water ad libitum and maintained in experimental pens during tropical conditions (temperature 34-41°C and 47% humidity). Polyphenols were fed at 125 and 250 ppm with and without distillers dried grains with solubles (DDGS) and antibiotic growth promoter (AGP). One way analysis of variance (ANOVA) was performed to assess the significant difference among treatment groups. Results indicated that experimental diets supplemented with polyphenols (T2, T3) alone significantly (P<0.01) reduced haemoglobin (Hb) levels compared with the control (T1), while polyphenols supplemented at 125 and 250 ppm in combination with DDGS significantly improved Hb levels compared with the control (T4). Administration of polyphenols at 125 and 250 ppm in corn-DDGS diets increased (P<0.05) the immune response i.e., foot pad index in response to phytohaemagglutunin (PHA-P), Newcastle vaccination (ND) titres as compared with diets supplemented with DDGS (T4- control). Production performance did not show a significant difference among treatment groups. In conclusion, polyphenols at 125 and 250 ppm in combination with 5% DDGS improved (P<0.05) broiler production especially immunity and erythrocyte membrane resistance under hot climatic conditions.
Owing to the increased efficiency, growth rate and reduced mortality achieved, antibiotics have been used continuously in the broiler industry for decades (Cromwell, 2002) and are being questioned for antibiotic resistance. Some of the alternatives include vitamins, minerals, herbal drugs, plant extracts, phytobiotics and antimicrobial peptides and beneficial bacteria (Yadav et al., 2016). Recently, there has been increased interest given to polyphenols from researchers and the wider food industry. Several studies have explored the anti-inflammatory, anti-allergic, immunomodulatory and anti-mutagenic activities, anticancer, and cardiovascular protective effects (McCullough et al., 2012) besides their antimicrobial activity. Polyphenolic tannins exert both positive and negative effects as they possess anti-nutritive properties, but are also beneficial for health due to their antimicrobial, anti-oxidative properties and their ability to stimulate the immune system and various effectors (Quideau et al., 2011). Further, bioavailability of proteins is questionable in polyphenol enriched broiler diets and may vary among protein sources. DDGS which are being used in broiler diets have high energy and protein content which make them an attractive substitute for expensive sources of energy and protein ingredients in poultry feed. The present study was undertaken to investigate the multifaceted effects of tamarind based polyphenol extracts and their combination with different protein sources on haematology, immunity and production of broilers reared from 0 to 42 days under tropical conditions.
II. MATERIALS AND METHODS
A total of 280 day old straight run commercial broilers (CARIBRO Vishal) were randomly assorted into 7 treatment groups (with 5 replicates each consisting of 8 birds): Basal diet without antibiotic growth promoter (AGP) as control (T1); Basal diet with 125 (T2) and 250 ppm (T3) polyphenols; Basal diet with 5% DDGS replacing 5% soybean meal (T4); Basal diet with 5% DDGS replacing 5% soybean meal and 125 ppm polyphenols (T5); Basal diet with 5% DDGS and 250 ppm polyphenols (T6); Basal diet with 0.025% AGP-bacitracin methylene disalicylate (T7). Comparisons for T2, T3 and T5, T6 were made with their respective controls i.e., T1 and T4. All birds were maintained under standard managemental conditions and a tropical environment and experimental diets were fed ad libitum. Tamarind seeds (TS) that were procured locally were extracted as per Razali et al. (2012) with methanol as a solvent in 1:10. Solvents were then removed using a rotary evaporator and the residues were directly mixed with the feed. For production attributes, body weight (BW), body weight gain (BWG), feed intake (FI) and feed efficiency (FE) and mortality were calculated. Haemoglobin (Hb) and erythrocyte osmotic fragility (EOF) were determined as per Sahli’s acid haematin (Sahli, 1909) and Buffenstein et al. (2001) respectively. For humoral immunity, Haemagglutination inhibition (HI) titer (OIE, 2012) and ELISA based antibody titer (IDEXX, USA) to Newcastle disease (ND) were estimated in serum on 14 and 21 dpi. Cutaneous basophilic hypersensitivity (CBH) was evaluated in terms of foot pad index (FPI) for the assessment of cell mediated immunity as per Cheng and Lamount (1988) in response to PHA-P. Results were subjected to one way ANOVA using SPSS 16.00 to assess the significant differences at 5% and 10% level among various groups with tukey’s post hoc test.
III. RESULTS AND DISCUSSION
Body weight and body weight gain (fortnightly) were significantly affected by polyphenols in birds fed with corn-soy (T2, T3) and corn-DDGS (T5, T6) diets to 4 weeks of age. However, final (42 days) live BW and BWG (Tables 1, 2) showed no significant difference among the treatment groups. Aengwanich et al. (2009) also found similar results. Brenes et al. (2010) with grape polyphenols found no significant (P>0.05) effect on FI and FE. In contrast, Masek et al. (2014) and Gopi et al. (2017) found higher BWG in polyphenol supplemented groups. The polyphenol source might be the reason for this difference. Sinchaiyakit et al. (2011) demonstrated higher (>30%) amounts of tannic acid content in TS coat husk. Direct interaction of polyphenols (rich in tannins) and some components such as proteins and polysaccharides can occur with binding affecting absorption (Gopi et al., 2017). FE was reduced (P<0.05) in T5 and T6 compared to their corresponding control and corn-soy diets. Treatment groups T2 and T3 had significantly (P<0.01) lower Hb levels than the control (T1), while those supplemented with DDGS based diets (T2,T3) significantly (P<0.05) improved Hb levels.
Polyphenols in corn-soy diets (T2,T3) have slightly improved the membrane strength of erythrocytes (Table 3) at 0.5% saline concentration. Polyphenols in corn-soy diets did not improve FPI (Table 4) in relation to the control (T1). Polyphenols at 125 ppm (T2) showed significant (P<0.01) reduction in CMI response associated with higher mortality rate (Table 3). T6 group had improved (P<0.01) immunity to ND on 14 and 21 dpvon and immunity to PHA-P (P<0.01). The modulating effects of polyphenols on immune function are mediated mainly via the inflammatory responses in macrophages which in turn initiate the production of pro-inflammatory cytokines (Cuevas et al., 2013). It appears that unidentified factors in DDGS might have some role that enhances the polyphenol induced immunity.
Supplementation of polyphenols at 125 and 250 ppm in combination with 5% DDGS based diets improved (P<0.05) broiler production especially immunity and erythrocyte membrane resistance under tropical conditions. Polyphenols did not improve production performance.
ACKNOWLEDGEMENTS: The authors are thankful to the Indian Council of Agricultural Research (ICAR) and Director, ICAR-CARI for providing necessary facilities to carry out this research work.
Abstract presented at the 30th Annual Australian Poultry Science Symposium 2019. For information on the latest edition and future events, check out https://www.apss2021.com.au/.