Evaluating 20% and 40% Inclusion of Sugary Former Foods in Pig Diets: Effects on Growth Performance, Feeding Behaviour, Carcass and Meat Quality Traits

Former food products (FFP) are food industry leftovers that can be used as feed ingredients. We investigated the effects of sugary FFP on growth, feeding behaviour, carcass and meat quality of pigs fattened to a heavy weight. Three inclusion levels were tested: 0% (FFP-0 = control), 20% (FFP-20) and 40% (FFP-40) FFP in grower (20-60 kg BW), finisher 1 (60-100 kg BW) and finisher 2 (100-140 kg BW) phase. A total of 36 castrated pigs were used, with 12 pigs within a litter assigned to each treatment, housed in a single pen equipped with automatic feeders that allowed recording of individual (ad libitum) feed intake at each visit. The pigs were slaughtered in two batches at the age of 190.9 ± 1.5 days and BW of 144.7 ± 8.8 kg. At slaughter, carcass weight, longissimus dorsi (LD) pH and carcass traits were measured. The following day, body composition of carcasses was determined using dual-energy X-ray absorptiometry and then carcasses were dissected into primal cuts, and meat quality was assessed. Data were analysed with SASV9.4 (PROC MIXED), with diet as a fixed effect and litter (dam) as a random effect in the model. Linear effects of sugary FFP inclusion were tested. In the grower period, daily feed intake and daily gain decreased with increasing sugary FFP inclusion. In finisher periods, a tendency towards lower daily feed intake was observed with increasing sugary FFP inclusion, which did not affect daily gain, but led to better feed conversion in the finisher II period. In the grower period, no differences in feeding behaviour were observed, while in finisher II period, FFP-20 pigs spent the shortest time at the feeder, consumed more feed per minute, had a longer interval between visits, but tended to go to the feeder more often than the FFP-0 or FFP-40 pigs. Compared to control, the sugary FFP inclusion was associated with increased carcass protein and water and decreased fat content, in line with thinner backfat. The decrease in ultimate pH and CIE (Commission Internationale d'Eclairage) colour parameter L* of LD were the only significant effects on meat quality. The backfat fatty acid composition was affected by sugary FFP inclusion (more monounsaturated fatty acids and less polyunsaturated fatty acids with higher ∑n6:∑n3 ratio). In summary, the sugary FFP inclusion of up to 40% had a limited effect on growth performance and meat quality but resulted in less deposition of fat and altered adipose tissue fatty acids profile.