Intake and digestibility of ‘Coastal’ bermudagrass hay from treated swine waste using subsurface drip irrigation
Waste handling systems for confined swine production in the upper South (approximately 32–37° N and 79–93° W) depend mainly on anaerobic lagoons and application of the waste effluent to cropland. The main objective of this study was to evaluate the quality of ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] hay receiving effluent generated from a raw swine waste treatment system designed to reduce P and K concentrations and delivered by subsurface drip irrigation (SDI) compared with hay produced from commercial N fertilizer. Eight treatments, consisting of commercial N fertilizer or effluent, each irrigated at two irrigation rates (75 and 100% of estimated evapotranspiration) and two lateral spacings (0.6 and 1.2 m), were compared with a control treatment of commercial N fertilizer without irrigation. Three harvests were taken in each of 2 yr and five of the six evaluated using wether sheep (30–45 kg). Greatest dry matter intake (DMI) per unit body weight occurred for the control vs. all irrigated treatments (1.94 vs. 1.77 kg 100–1 kg; P = 0.02; SEM = 0.11). Among irrigated treatments, DMI was greatest from commercial N vs. effluent (1.81 vs. 1.71 kg 100–1 kg; P = 0.05; SEM = 0.11). Dry matter intake was similar for the 75% rate treatments and the non-irrigated treatment (mean, 1.87 kg 100–1 kg) but was reduced for the 100% rate (1.94 vs. 1.72 kg 100–1 kg; P = 0.03; SEM = 0.11). Hay from the 75% rate was more digestible than hay from the 100% rate (527 vs. 508 g kg–1; P = 0.03; SEM = 21). The SDI system functioned well, and lateral spacing did not alter hay quality. Treated waste from a raw waste treatment system was readily delivered by SDI at the recommended rate to produce bermudagrass hay of adequate quality for ruminant production systems.