Hydrocyanic acid content and growth rate of sorghum x sudangrass hybrid during fall

Abstract

In central Brazil after soybean or other annual agricultural species is harvested, sorghum hybrids are planted in the fall in order to establish pastures for grazing animals. This study conducted for two consecutive years aimed at quantifying the contents of hydrocyanic acid in the leaves and determining plant height, forage dry matter yield and the leaf/stem ratio for sorghum hybrid 1P400 at different ages. Statistical analysis was performed by regression analysis based on plant age. Leaf HCN content decreased with plant growth, ranging from 205.0 and 230.3 mg HCN/100 g leaf DM at two weeks old to 5.9 and 6.1 mg HCN/100 g leaf DM at five weeks old in the first and second year, respectively. The average heights measured varied from 60 and 56 cm, in the 4 th week, to 117 and 151 cm, in the 8 th week, during the first and second experimental year, respectively. Forage mass increased linearly with age and displayed average of 1.411 and 1.637 kg DM/ha in the first year and, 2.905 and 3.640 kg DM/ha in the second year, during the 7 th and 8 th week, respectively. Leaf proportion decreased while stem increased linearly with plant age. The leaf/stem ratio decreased with plant growth, elongation and increasing stem weight. The sorghum hybrid should be grazed only after five weeks or when the plant height is above 80 cm, in order to avoid the risk of cyanide poisoning.Index terms: Annual grasses, cyanogenic plants, picro-sodium test, toxic plant. RESUMONo Brasil Central, híbridos de sorgo podem ser semeados no outono, após a colheita da soja ou outra espécie de planta anual, com o objetivo de fornecer alimento aos ruminantes por meio de pastejo. O trabalho foi desenvolvido, por dois anos consecutivos, com o objetivo de quantificar os teores de ácido cianídrico das folhas e mensurar a altura das plantas, produção de massa seca de forragem e a proporção de folha e colmo nas diferentes idades do hibrido de sorgo IP400. A análise estatística foi realizada por meio de análise de regressão em função da idade das plantas. O teor de HCN nas folhas decresceu com o desenvolvimento das plantas, apresentando 205,0 e 230,3 mg HCN/100 g de MS de folha, com duas semanas de crescimento e 5,9 e 6,1 mg HCN/100 g de MS de folha, na quinta semana de crescimento, no primeiro e segundo ano, respectivamente. As plantas apresentaram em média 60 e 56 cm, na 4ª semana, e 117 e 151 cm na 8ª semana, no primeiro e segundo ano, respectivamente. A massa de forragem aumentou linearmente, com a idade, apresentando, em média, na sétima e oitava semanas de avaliação, 1.411 e 1.637 kg de MS/ha no primeiro ano e 2.905 e 3.640 kg de MS/ha no segundo ano, respectivamente. Com o crescimento das plantas, a proporção de folhas diminuiu e a proporção de colmo aumentou linearmente. A relação folha/colmo diminuiu com o crescimento, com o alongamento das plantas e aumento do peso dos colmos. O híbrido de sorgo deve ser pastejado, somente após a quinta semana de crescimento ou quando as plantas tiverem acima de 80 cm para não haver risco de intoxicação por HC...

Review: Hidrogen Sianida dan Implikasinya pada Ternak

“…Kandungan HCN pada rumput gajah (Pennisetum purpureum) tergantung dari musim, dimana kandungan pada saat musim hujan lebih tinggi dibandingkan dengan musim kemarau, meskipun tidak berbeda jauh. Rata-rata kandungan HCN pada rumput gajah adalah 1,58 mg/100g (Onyeonagu et al, 2013 (Pickrell et al, 1991) tetapi kandungan tersebut akan menurun seiring dengan umur tanaman (Etuk et al, 2012;Simili et al, 2013).…”

The Effect of Variety and Harvesting Time of Sorghum Planted in Stylosanthes Pasture on Growth, Production and Prussic Acid Content

“…Excessive prussic acid content will cause poisoning in cattle where hemoglobin cannot bind oxygen in the blood. The content of prussic acid is above 1,000 mg/kg of dry matter (Simili et al, 2013). The purpose of this study was to determine the effect of sorghum varieties and harvesting time of sorghum planted in stylosanthes pastures base on growth, production and prussic acid content.…”

“…The ratio of Super-2 stems and leaves was 1.96, while BMR was 2.74. Simili et al (2013) stated that sorghum is cut when plant height is between 90 to 100 cm, with a stem and leaf ratio of 0.8 to 1.5 and a low prussic acid content. The results of statistical analysis showed that harvesting time had a significant effect (P<0.05) on the prussic acid content.…”

“…This is because the older the plant contain lower the percentage of leaves. Simili et al (2013), stated that Sorghum bicolor at 70 days of cutting has a prussic acid content about 487 mg/kg and decreases at 100 days of cut which has 200 mg/kg. 1,000 mg/kg dry matter of prussic acid content is dangerous for livestock because it will cause poisoning.…”

O manejo de cortes modifica o filocrono, o crescimento e a produção do sorgo forrageiro sob ambiente de temperatura amena

“…These cuts occurred according to the recommendation for the crop, after reaching 50 cm in height (Neumann et al 2010). This is because young plants contain durrina, which turns into hydrocyanic acid in the rumen, making them toxic (Tamele et al 2009;Simili et al 2013).…”