Dietary flavonoids advance timing of moult but do not affect redox status of juvenile blackbirds (Turdus merula)

Abstract

Flavonoids are the most abundant plant polyphenols, widely occurring in fruits and berries, and show a strong antioxidant activity in vitro. Studies of avian species feeding on berries suggest that dietary flavonoids have health-promoting effects and may enhance the expression of melanin-based plumage traits. These effects are probably mediated by the antioxidant activity of flavonoids. However, the effect of dietary flavonoids on oxidative status has never been investigated in any bird species. We analysed the effects of dietary flavonoids on blood non-enzymatic antioxidants and protein oxidative damage of juvenile European blackbirds (Turdus merula). In addition, we analysed the effects of flavonoid-enriched diet on body condition and on the timing of moult from juvenile to adult plumage. Dietary flavonoids did not significantly affect redox status but significantly advanced the onset of moult, hastening plumage development. Moulting birds showed higher protein oxidative damage compared with those that had not yet started moulting. The probability of initiating moult after 40 days of dietary treatment was higher for birds with low circulating levels of oxidizing agents and high glutathione concentration. The metabolization of flavonoids could have altered their redox potential, resulting in no net effects on redox status. However, flavonoid consumption before and during moult may contribute to enhance plumage development. Moreover, our findings suggest that moulting feathers may result in redox imbalance. Given their effect on moult and growth of melanin-rich feathers, fruit flavonoids may have contributed to shape plant fruiting time in relation to fruit consumption preferences by birds.

Seasonality, diet, and physiology as a predominant control factors of the moult dynamics in birds – a meta-analysis

“…Our meta-analysis showed that moult intensity was the most sensitive to diet alterations. It is in line with individual results: a wellbalanced diet (Pap et al, 2008) and additional dietary flavonoids (Pap et al, 2009;Cecere et al, 2016) enhanced the process of feather renewal. Flavonoid-enriched food may facilitate pigment synthesis,…”

Meta-analysis reveals that reproductive strategies are associated with sexual differences in oxidative balance across vertebrates

“…The following exclusion criteria were applied: i) studies that measured expression of antioxidant genes because I were interested in the biochemical differences between sexes; ii) studies that used metrics of free radical generation as an index of oxidative stress, since they do not provide direct evidence of oxidative stress (reactive species might be mopped up before oxidative damage is generated); iii) studies where necessary information for calculating effect size was unavailable. Overall, the final dataset included 732 effect sizes from 100 articles (82 species: 7 fish, 5 reptiles, 44 birds, and 26 mammals) (Almroth et al 2008; Alonso-Alvarez et al 2004a, 2004b; Barrera-García et al 2012; Beamonte-Barrientos and Verhulst 2013; Beaulieu and Schaefer 2014, Beaulieu et al 2010, 2011, 2014; Bertrand et al 2006; Bilham et al 2013; Bize et al 2008; Bonisoli-Alquati et al 2010; Canovas et al 2014; Casagrande et al 2011, 2012a, 2012b; Cecere et al 2016; Christensen et al 2015; Christie et al 2012; Cohen et al 2008; Costantini and Bonadonna 2010; Costantini and Dell’omo 2015; Costantini et al 2007, 2008, 2010, 2012a, 2012b, 2013, 2014, 2014a, 2014b; Costantini 2010; Cram et al 2015a, 2015b; Depboylu et al 2013; Ehrenbrink et al 2006; Emaresi et al 2016; Figueiredo-Fernandes et al 2006b; Georgiev et al 2015; Gomes et al 2014; Grunst et al 2014; Heiss and Schoech 2012; Herrera-Dueñnas et al 2014; Isaksson et al 2009, 2011, 2013; Isaksson 2013; Jolly et al 2012; Kamper et al 2009; Kanerva et al 2012; Kayali et al 2007; Kurhalyuk et al 2009; Langley-Evans and Sculley 2005; Leclaire et al 2015; Lilley et al 2014; Lopes...…”

Effect of packaging on phenols, flavonoids and antioxidant characteristics of mechanical cabinet dried wild pomegranate (Punica granatum L.) arils

“…Phenolic compounds have free radical scavenging abilities, anti-mutagenic and anti-carcinogenic activities and can reduce the risk of cardiovascular and carcinogenic diseases (Nakamura et al, 2003). Flavonoids are the most abundant plant polyphenols occurring in fruits with strong antioxidant activity and disease-preventing properties against cancer and cardiovascular diseases (Wang and Ho, 2009;Cecere et al, 2016). The various flavonoids like anthocyanins, ellagic acid derivatives and hydrolysable tannins (punicalagin, gallic and ellagic acid) are responsible for the antioxidant activity of pomegranate fruit and a very high antioxidant activity in the wild and cultivated pomegranate fruit extracts (peel, juice and seeds) have been observed by various researchers (Gill et al, 2000;Aviram et al, 2000;Singh et al, 2002;Thakur et al, 2018;Hamid et al, 2020a).…”