Expeller-pressed and solvent-extracted Pongamia seedcake as a protein supplement for cattle consuming a basal diet of forage

Three studies were conducted evaluating expeller-pressed (EKC) or solvent-extracted (SKC) Pongamia seedcake (PSC) as protein supplements for beef cattle. To determine palatability, EKC or SKC were mixed with wheat middlings (WM) at 200, 400, or 600 g/kg, and offered to seven steers in a 7 × 7 Latin square. Solvent-extracted PSC was more palatable than EKC, and could be included at up to 400 g/kg of supplement without negatively affecting consumption; EKC could be included at 200 g/kg without significantly decreasing extent or rate of consumption compared to control. However, inclusion of both EKC and SKC resulted in linear (P < 0.01) decreases in both extent and rate of consumption. To determine nutrient utilization/N balance, five treatments consisting of a control (no supplement, NOSUPP) and four isonitrogenous levels of supplementation (100 mg of N/kg BW) 0 g/kg of the supplement as PSC (0PSC), 400 g/kg of the supplement as SKC (400SKC), 200 g/kg of the supplement as EKC (200EKC), and 400 g/kg (400EKC) of the supplement as EKC, were dosed ruminally into five ruminally cannulated steers in a 5 × 5 Latin square. Steers were fed low-quality hay (62 g of CP/kg DM) to determine the effects of source and level of PSC on forage utilization. Forage DM intake was not different (P > 0.05) between 200EKC (4.71 kg/d) or 400SKC (4.88 kg/d), but both were less (P < 0.05) than 0 PSC (6.12 kg/d). Infusion of 400EKC resulted in the least forage intake (3.57 kg/d) which was less than (P < 0.05) NOSUPP (5.25 kg/d). Nitrogen retention for all PSC-containing supplements was less (P < 0.05) than 0 PSC, but was more (P < 0.05) than NOSUPP for 200EKC and 400SKC. In the long-term feeding study, fifteen steers, five per treatment, were assigned to either a positive control (0PSC), 200 g/kg EKC (200EKC), or 200 g/kg of supplement SKC (200SKC) supplement for 126 days to determine the long-term effects of feeding PSC. Supplementation with 0PSC resulted in greater (P < 0.05) total OM intake (6.79 kg/d) compared to 200EKC and 200SKC (5.69 and 5.42 kg/d). Average daily gain of steers on either PSC supplement was significantly lower (P < 0.05) than that of control steers (0.60 kg/d), but similar between the two PSC groups (0.39 and 0.38 kg/d for 200EKC and 200SKC, respectively). Additional research is required to full elucidate the components of PSC that negatively effect beef cattle performance and to determine the effectiveness of possible mitigation strategies.