Effects of β-carotene on adult immune condition and antibacterial activity in the eggs of the Grey Partridge, Perdix perdix Marco Cucco ⁎ , Beatrice Guasco, Giorgio Malacarne, Roberta Ottonelli University of Piemonte Orientale, DiSAV, via Bellini 25, I-15100 Alessandria, Italy Received 31 October 2006; received in revised form 6 March 2007; accepted 12 March 2007 Available online 19 March 2007 Abstract Carotenoids are important dietary constituents in birds. Their functions are numerous and complex, and breeding females are potentially faced with an optimal allocation of these resources between themselves and offspring. We conducted a dietary experiment (low and high supply of β- carotene) to examine the effect of β-carotene on health and immune response of 64 reproducing pairs of Grey Partridge (Perdix perdix L.) and on the quality of their eggs, as revealed by the measurement of biochemical components in yolk and albumen, the egg hatching rate and chick survival. We found a beneficial effect of β-carotene on the erythrosedimentation rate and immune response of females (PHA reaction), while the diet did not significantly affect these variables in males. In both sexes, the plasma level of carotenoids was not related to the quantity of β-carotene supplied. A higher quantity of β-carotene in the diet did not induce a variation of egg nutrients (proteins and lipids), nor an increase of yolk β- carotene concentration. We detected a higher concentration of lysozyme, an enzyme with antibacterial activity, in the albumen of eggs laid by females with a high supply of β-carotene. These eggs showed higher hatching rates. The present study indicates that although carotenoid supplementation does not influence blood and yolk carotenoid levels, it results in better immune conditions of females, eventually translated into increased antibacterial activity of the eggs. The broad range of beneficial effects of carotenoids is discussed. © 2007 Elsevier Inc. All rights reserved. Keywords: β-carotene; Adult health; Immunity; Egg quality; Lysozyme; Maternal effects; Perdix 1. Introduction Models of optimal parental investment require knowledge of the aspects of maternal phenotype that influence propagule quality (Bernardo, 1996). In oviparous animals, maternal fitness is influenced by egg production, since this is an energetically expensive process that can influence future reproductive prospects (Williams, 1975). In turn, egg quality can profoundly influence the fitness of the offspring, so that the distribution of reserves within a clutch can be considered an evolutionarily strategic decision (Mousseau and Fox, 1998). Carotenoids are important dietary constituents. They play numerous physiological roles in both the laying female and developing embryo, and they are resources that mothers allocate between herself and the progeny. However, factors determining the absorption of carotenoids and their utilization for different functions are numerous and complex, and causal relationships are generally poorly known (Bortolotti et al., 2003; Costantini and Dell'Omo, 2006). Carotenoids are fat soluble components present in adult females and eggs (yolk) believed to be responsible for maternal effects in birds (Royle et al., 1999; Blount et al., 2002). Aside from their role in pigmentation (Hill et al., 2002), carotenoids are extremely important in a variety of physiological and immunological processes in adult birds (Møller et al., 2000). In a detailed study on the Lesser Black-backed Gull Larus fuscus (Blount et al., 2002), a supplemental feeding experiment showed that carotene-fed gulls had higher plasma antioxidant activity and higher concentrations of carotenoids. Interestingly, carotene-fed females also had a low plasma concentrations of immunoglobulins. Oviparous animals provision their egg yolk with carotenoids. It now appears that these pigments, which give a yellow-red colour to the yolk, play various physiological roles in developing birds, thus suggesting new perspectives on reproductive trade- Comparative Biochemistry and Physiology, Part A 147 (2007) 1038 – 1046 www.elsevier.com/locate/cbpa ⁎ Corresponding author. University of Piemonte Orientale, Department of Environmental and Life Sciences, via Bellini 25, I-15100 Alessandria, Italy. Fax: +39 0131 360243. E-mail address: cucco@unipmn.it (M. Cucco). 1095-6433/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.cbpa.2007.03.014