Reduce, recycle and reuse: tomato and pepper from food waste for diets of end-of-lay hens in a sustainable egg production system. Egg quality traits

The commercial value of spent laying hens has long been considered negligible, but today consumers pay more attention to the living conditions of hens, driving the market toward ethical and sustainable farming systems. Aim of this work was to evaluate the possibility of rearing spent hens and the effect of rearing system and use of food waste on eggs quality. A total of 300 ISA Brown laying hens (20 weeks old) were raised in barn and fed with commercial diets. Hen day egg production (HDEP) and average egg weight were recorded daily. At 70 weeks of age, hens were divided into 3 groups: one group (CTRIN) was left in the farm, under the same conditions and diet. The two other groups were transferred in outdoor system and fed one with the same commercial diet (CTROU) and one (TPOU) with a basal diet and an integration of tomato (5%) and pepper (2.5%) waste collected from a commercial processing local plant. Laying performance were recorded further 30 weeks. At week 70 and at week 100, eggs were sampled for quality evaluation. Physical and chemical parameter, fatty acids profile and total polyphenols content were determined. As expected, from 24 weeks of age, egg production rates exceeded 90% until 46-48 weeks and declined to approximately 74% at 70th week of age. From week 70 CTRIN drastically reduced HDEP to 16% at week 82. CTROU and TPOU groups, after a period of adaptation, maintained an HDEP of approximately 70-75% until week 100. As regard the egg quality, the 3 groups showed similar characteristics. The weight of whole egg, at week 100, was 63.8 gr in TPOU, similar to weight of CTRIN group at week 70 (63.2 gr), while CTROU showed eggs significantly lighter (59.95 gr; p=0.038) at the end of the trial. The average weight of the eggs’ components, as well as the gross composition, were not significantly (p < 0.05) different between groups. Yolk color, measured by Roche Color Fan, significantly increased for TPOU hens (12.7), followed by the CTROU (9.9) and CTRIN (7.4) groups (p<0.0001), suggesting the transfer of carotenoids from feed to eggs. Fatty acid profile was not influenced by the new rearing system or by the diet, instead the polyphenol content was higher in TPOU (4.42 mgGAE/g) in comparison with CTROU (3.5 mgGAE/g) and CTRIN group (2.39 mgGAE/g) (p=0.023). These preliminary results showed the really possibility to use the end-of-lay hens fed food waste in a sustainable niche market, for “ethic eggs” production.