Effects of dietary supplementation with vegetable oils of different unsaturated fatty acids composition on intake, digestibility, nitrogen balance performance, and carcass traits of sheep

We aimed at evaluating the best unsaturated fatty acid candidate (vegetable oil) for blending (dry matter-DM basis) with cashew nutshell liquid (CNSL) to improve feed intake, digestibility, nitrogen balance, growth, and carcass traits in sheep. Forty uncastrated male Santa Ines × Dorper crossbred sheep (n = 8/treatment) weighting 24.44 ± 1.5 kg were used. Animals were randomly assigned to a completely randomized design and received one of the following treatments: a control group consisting of a blend of phenolic lipids (CNSL at 0.5%) and canola oil (a monounsaturated fatty acid source, MUFA, at 1.5%), and four treatment groups with CNSL (0.5%) combined with 1.5% of a high polyunsaturated fatty acid (PUFA) vegetable oil (corn, soybean, sunflower, or cottonseed oil), as DM basis. Feeding sheep with CNSL + canola oil resulted in higher SFA, UFA, and MUFA and lower PUFA’s (P < 0.05) intakes. The TDN intake was lower for the CNSL + corn oil diet than the other oils (P < 0.0001). The DM and NDF digestibility were higher for CNSL + cottonseed oil (PUFA) or canola oil (MUFA) diets than other oils (P < 0.05). The CNSL + soybean oil blend promoted a lower urinary N excretion (P = 0.047) in sheep. Growth and carcass traits were not affected by the oil’s composition in the blends. The level of saturation was confirmed as such a determining factor in the DM and NDF digestibility since the oil containing the highest concentration of MUFA (canola oil) showed better digestibility compared to other PUFA-rich oils; however, without effect on the performance and feed efficiency of the sheep.