This study was supported by Regione Autonoma Friuli Venezia Giulia 46th WEFTA Split, Croatia /12-14 Oct 2016 THE EFFECT OF THE PRE-SLAUGHTER FEEDING/FASTING SCHEDULE ON POST MORTEM QUALITY TRAITS OF RAINBOW TROUT Bongiorno T.a*, Fabbro A.b, Cancian G.b, Virgilio L.b, Cardinaletti G.b, Messina M.b, Tulli F.b, D’Agaro E.b, Lippe G.b, Stecchini M. L.b, Tibaldi E.b a CRITA S.c.a.r.l. Via Pozzuolo, 324, 33100 Udine, Italy bDepartment of Agricultural Food Environmental and  Animal Sciences, Udine University, Italy *Corresponding author: tiziana.bongiorno@uniud.it INTRODUCTION MATERIAL AND METHODS Despite the growing interest of the trout farming industry for filleting large specimens, few studies have investigated the influence of pre-slaughter feeding-fasting history of cultured fish on quality traits of raw fillets. Short pre-slaughter fasting periods (3-9 days) led to slight changes in Salmonid fillet quality, whereas longer starvation (35 days) resulted in improved pre-slaughter resistance to stress and delayed rigor (Lòpez-Luna et al., 2014; Bermejo-Poza et al., 2015; Mørkøre et al., 2008). Fig. 1 Experimental design and analysis carried out AIM To evaluate the effect of a 3-week pre-slaughter fasting or feed restriction period on the evolution of post mortem quality traits in rainbow trout F B C D E A Fig. 2 Determination of Biometric measurements (A), pH (B), color (C), WHC (D), texture (E) and liquid leakage (F) analysis in trout fillets after 21 days pre-slaughtering ration size or fasting RESULTS Table 1 Effect of pre-slaughtering ration size (FR and RR) or starvation (R0) on growth performance and biometric traits of rainbow trout. Data are mean values±SD, different exponent letters indicate significant differences among groups (P≤0.05). Table 2 Fillet composition of rainbow trout fed different pre-slaughter ration size (FR and RR) or kept starved (R0). Data are mean values ±SD of 5 fish analyzed in duplicate Fig. 1 Effect of pre-slaughtering ration size (FR and RR) or starvation (R0) on rigor index of whole rainbow trout during 72h ice-storage. Data points represent mean values±SD of 5 fish per group and time. Fig. 2 Effect of pre-slaughtering ration size (FR and RR) or starvation (R0) on muscle pH of rainbow trout fillet during 72h storage (+4°C). Data points represent mean values ± SD of 5 fish per group and time. FR RR R0 Fig. 3 Effect of pre-slaughtering ration size (FR and RR) or starvation (R0) on Water Holding Capacity expressed as Percentage of Water Released (PWR) of the rainbow trout fillet during 72h storage (+4°C). Data points represent mean values ± SD of 5 fish per group and time. Fig. 4 Effect of pre-slaughtering ration size (FR and RR) or starvetion (R0) on texture of rainbow trout fillet during 72h storage (+4°C). Data points represent mean values ± SD of thre muscle portion of 5 fish per group and time. Fig. 5 Effect of pre-slaughtering ration size (FR and RR) or starvetion (R0) on rainbow trout fillet color during 72h storage (+4°C). Data represent mean values ± SD of 5 fish per group. Fig. 6 Effect of pre-slaughtering ration size (FR and RR) or starvetion (R0) on muscle actin degradation of rainbow trout during the first 7h storage (+4°C). Severe feed restriction for 3 weeks in rainbow trout induced: Moderate weight loss (-1.6%), High variability in fish size, compromission of some quality traits such as WHC, texture and faster muscle actin degradation. Prolonged starvation period of 3 weeks in rainbow trout induced: Weight loss (-4.4%) and muscle redness, lower individual variability and condition factor, higher slaughter yield , higher pH values that improving the WHC and muscle firmness, longer pre-rigor phase and greater muscle contraction between 24-48h. Fillet proximate composition was not affected by the pre-slaughter treatment This study was supported by Regione Autonoma Friuli Venezia Giulia (L.R.26/05) CONCLUSIONS REFERENCES The present study suggest that an extended pre-slaughter fasting period could result in improved technological quality traits in rainbow trout Bermejo-Poza R., De la Fuente J., Perez C., Lauzirica S., Gonzàlez E., Diaz M.T., Villaroel M., 2015. The effect of intermittent feeding on the pre-slaughter fasting response in rainbow trout. Aquaculture 443, 24-30. López-Luna, J., Torrent, F., Villarroel, M., 2014. Fasting up to 34 °C days in rainbow trout, Oncorhynchus mykiss, has little effect on flesh quality. Aquaculture 420–421, 63–70. Mørkøre, T., Mazo, P.I., Tahirovic, V., Einen, O., 2008. Impact of starvation and handling stress on rigor development and quality of Atlantic salmon (Salmo salar L). Aquaculture 277, 231–238.