Leonard Lauriault and Naveen Puppala. 6502 Quay Rd. AM.5, New Mexico State University, New Mexico State University, Agricultural Science Center, Tucumcari, NM 88401
Forage harvests were taken weekly beginning 18 September, and those from the control treatment were left uncut. Pods from all plots were dug 23 October and left to cure at the soil surface. Forage from the control treatment was collected at threshing. Forage nutritive value was estimated by Near Infrared Spectroscopy. Differences (P < 0.05) existed for pod and forage organic yield and all nutritive value variables except phosphorus. Pod yield was unaffected when forage was harvested no less than three weeks prior to pod digging. Forage yield increased until 3 week prior to digging and then declined while forage crude protein and net energy for lactation declined fairly consistently as time progressed. The optimum compromise between pod and forage yield and maximizing forage nutritive value was harvesting forage approximately three weeks before digging the pods (3716 and 7098 kg ha-1 for pod and forage organic matter yield, respectively, 135 g kg-1 crude protein, and 1.4445 Mcal kg-1 net energy for lactation). Also, the calcium-to-phosphorus ratio is generally in excess of 6 to 1, which is near the upper recommended limit for ruminants. For non-ruminants, the Ca:P ratio should be 1:1 or 2:1. While forage yield and nutritive value were reduced by later harvest dates, possibly due to nutrient transfer to the pods, pod yield was unaffected. Kernel quality may be reduced, however, resulting in off-flavor.