Conventional use and sustainable valorization of spent egg-laying hens as functional foods and biomaterials: A review

Bioresources and Bioprocessing

Table 1 Proximate composition, fatty acid and amino acid profiles of raw spent hen and meat

Sample	Moisture (%)	Protein (%)	Fat (%)	Ash (%)	Fatty acid profile	Major amino acid	References
Spent hen carcass^a	59.8	18.5	14.9	5.3
Whole spent hen^b	58.2	17.9	19.1	4.5		Glu, Gly, Asp, Leu, Arg, Pro, Lys	Freeman et al. (2009a, b)
Whole spent hen^c	67.7	17.1	14.1	2.1			Zubair (2017)
Whole spent hen^d	60.1	21.4	16.3	2.2	SFA (28%), MUFA (50%), PUFA (22%)		Safder et al. (2019a, b)
Spent hen breast meat	72.0	22.9	1.5	1.5		Glu, Leu, Arg, Lys, Asp	Okarini et al. (2013)
Spent hen breast meat	73.9	21.7	3.8	1.3	SFA (38%), MUFA (33%), PUFA (29%)		Semwogerere et al. (2019)

SFA saturated fatty acids, MUFA mono-unsaturated fatty acids, PUFA poly-unsaturated fatty acids
^aSpent hen carcass (without feather, head, feet, and viscera), analyzed by our lab
^bWhole spent hen (with feather)
^cWhole spent hen (including skin, bone, muscle, leg, and gizzard)
^dWhole spent hen (no indication on body components)