Rumen kinetics of nutrient degradability of forage barley (Hordeum vulgare L.) with different levels of quinoa (Chenopodium quinoa) residues supplementation

The study aimed to determine the kinetic parameters of in situ degradation of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) in barley as a winter forage, supplemented with four levels (0, 10, 20, and 30%, based on natural matter) of quinoa residue (QR). The experimental design used was a randomized complete block with a 4 x 6 factorial scheme (4 levels, 6 incubation times) and three replications. Three adult rumen-fistulated cattle with an average live weight of 434.33 + 4.04 kg were employed. Five grams of samples were incubated at 0, 6, 12, 24, 48, and 72 hours. Time 0 was used for calculating the soluble fraction. There was no interaction between level and time in the degradability of DM, CP, and NDF. CP and NDF degradability were influenced by the levels. The maximum disappearances of CP (60.41 and 62.36%) were obtained at 24 and 48 hours of ruminal incubation with the addition of 8.77 and 11.57% QR to barley, respectively. The potential degradability of DM, CP, and NDF, although showing variations, averaged around 70%. Higher potential and effective degradability of NDF in barley were observed with 10% QR compared to barley with 0, 20, and 30% QR. Barley supplemented with 10 and 30% QR promotes greater effective degradability of CP, suggesting increased utilization of this nutrient. The highest degradation rates (DR) of CP and NDF were observed at the 10% QR level, a parameter that classifies barley with QR as a high-quality forage resource.