EFFECT OF CUTTING AND POST-CUTTING INTERVALS ON HYDROGEN CYANIDE IN SORGHUM FORAGE GROWN UNDER RAIN-FED CONDITIONS

Abstract

Sorghum forage either green or dry is the main source of livestock feed in dry areas of Pakistan. However, a lethal risk of hydrogen cyanide (HCN) is associated with this forage. Therefore, a study was carried out under rainfed conditions to assess HCN contents in three commonly grown sorghum cultivars viz., JS-2002, Chakwal Sorghum and Local Cultivar at three growth stages i.e. 3rd leaf (GS1), pre-booting (GS2) and 50% heading stage (GS3) and at three post cutting intervals i.e., 06, 12 and 18 hours. The results of this study identified forage sorghum cultivar JS-2002 with lowest HCN content grown under rainfed conditions and is safer for livestock feeding at pre-booting stage. Moreover, this study has provided clear evidence that HCN contents were very high at early growth stages of crop in all the cultivars and decreased with the advancement of the growth stages. The post cutting intervals have also indicated that HCN contents decreased in all the cultivars as the post-cutting intervals (18 hours) were prolonged in comparison with fresh cutting. Thus, based on these results it is concluded that forage sorghum cultivar JS-2002 at GS2 and after18 hours of cutting interval has the lowest HCN contents. The improved cultivar JS -2002 also has higher % of crude protein, crude fiber in comparison with Chakwal Sorghum and Local Cultivar. Therefore, livestock rearing farmers of rain-fed region are advised to grow JS-2002 for safer grazing of sorghum forage from HCN toxicity to animals at booting stage with more digestibility and nutritional value.