LAUSR

Characterizing the waste generated from different agro-industrial segments enables the strategic management of residues, with the goal of maximizing recovery within the premises of a circular economy. This research aimed to determine the coefficient of waste generated in broiler chick hatcheries as well as to characterize the waste, taking into account the points of culling and the ages of the laying hens. Furthermore, the waste was used in composting with sheep manure (SM) at increasing inclusion rates (0:100, 10:90, 20:80, 30:70, 40:60, and 50:50). On average, 0.16 kg (DM) of hatchery waste is generated per kg of broiler chicks born. At the hatchery, at least 79% of the total disposal occurs at the hatcher stage. This value is impacted by chicken age (P < 0.05), with birds of a late laying age generating waste with higher contents of carbon (C), volatile solids (VS), ether extract (EE), and nitrogen (N). Culling during egg reception and the manual transfer process account for only 1.8% of the total waste generated on average and thus contribute little to the composition of the overall residues. However, the mechanical transfer process may represent up to 19.0% of the total waste generated by hens of an intermediate laying age. According to the average of all the composting stages, the maximum reduction in solids and C from the hatchery waste was reached when the waste accounted for 50% of the windrow composition. Such conditions resulted in organic fertilizer with the highest N content (2.8%), equivalent to 40.0% more than that in the treatment with no added hatchery waste. The compost resulting from 50% hatchery waste inclusion also had the highest humic acid to fulvic acid (HA:FA) ratio and the highest calcium content due to the higher proportion of eggshells. These findings lead to the recommendation for the inclusion of hatchery waste in composting with SM at a 50% rate by mass.