Use of cucumber waste silage as an alternative forage source for sheep

Horticultural production in the Mediterranean basin generates considerable quantities of by-products, which, if not valorised, can pose environmental problems. This study evaluated the potential of cucumber–straw silage as an alternative forage for sheep. Eighteen Segureña sheep (10 months old; 30 ± 0.4 kg BW) were allocated to two experimental forages: oats hay (CTL, 985 g/kg DM) or cucumber–straw silage (SIL, 15 g/kg DM). The SIL forage contained more NDF (780 vs. 516 g/kg DM) and less CP (64.9 vs. 82.9 g/kg DM) than CTL. The trial included one week of adaptation with ad libitum feeding followed by two weeks of restricted intake. Measurements during the last week included digestibility, N balance, rumen fermentation, and blood metabolites. Results indicated that health status remained unaffected, and DMI was similar under ad libitum feeding. Under restricted intake, SIL-fed sheep displayed slightly higher DMI (+12 %), greater digestible energy intake (+33 %), and higher ruminal acetate (+10 %) and butyrate (+40 %), accompanied by increased blood β-hydroxybutyrate concentrations (+89 %). Despite lower CP intake, SIL-fed animals exhibited higher ruminal iso-acid proportions and blood urea N, suggesting enhanced proteolysis and urea recycling. These compensatory mechanisms resulted in similar ruminal NH 3 -N levels and microbial protein synthesis across treatments, although N retention and efficiency were significantly lower in the SIL group. In conclusion, SIL represents a feasible energy source for sheep, although its limited protein content may require further N supply in high-yielding ruminants. This silage valorisation could reduce food waste and improve circular agriculture and sustainability in livestock production. • Horticultural production generates considerable quantities of waste. • Unmarketable cucumbers can be ensiled with straw as an alternative forage. • Cucumber silage has less protein and more fibre than oats hay. • Cucumber silage increased fibre degradation and digestible energy supply. • Its low N content was partially compensated with higher proteolysis and N recycling.