Effects of different rates of drying cassava root on its toxicity to broiler chicks

Abstract

1. The effects of drying cassava root at different rates on its composition and toxicity to broiler chicks were examined. Unpeeled roots from a high-cyanide cultivar of cassava were chipped and dried at 25 degrees C to a moisture content of below 100 g/kg over 24 h for fast-dried meal (FD) or 72 h for slow-dried meal (SD). The meals were incorporated at 250 and 500 g/kg into semi-synthetic diets which were fed to day-old broiler chicks as mash or pellets in separate experiments. 2. The two drying rates produced meals with similar concentrations of polyphenols, but different concentrations of cyanogens, the latter being 38 and 482 mg total cyanide/kg for SD and FD, respectively. The linamarin, acetonecyanohydrin or total cyanide content measurements of pelleted diets were highly correlated. 3. Growth rates of chicks fed on SD-based diets were significantly higher than those of chicks fed on FD-based diets. Compared with a control diet, weight gain of chicks fed on the 500 g FD/kg diet (containing 258 mg total cyanide/kg) was 77% lower, although performance also appeared to be reduced at 142 mg total cyanide/kg. 4. The ratio of water:food intake of chicks was higher in FD than in SD groups, and this was reflected in the high water content of excreta. There was increased bile excretion, the chloretic effect increasing with the cyanogen content of diet. Pancreas weights were lower in FD than in SD groups in experiment 1 (mash diets), but not in experiment 2 (pelleted diets), while there was a significant interaction between drying method and cassava inclusion rate on liver weight in experiment 2, but not in experiment 1. There were no effects on the mortality rate. 5. Pelleting of diets generated high temperatures, but did not significantly alter the cyanogen concentration or the growth of the chicks. 6. Thus, slower rates of drying cassava roots produce meals with lower cyanogen concentration that are, consequently, less toxic to broiler chicks. Cassava root meal of less than 40 mg total cyanide/kg can be fed to broiler chicks at 500 g/kg without any adverse effects.

The Use of Cassava, Sweet Potato and Cocoyam, and Their By-Products by Non – Ruminants

“…Phytic acid is the primary storage compound of phosphorus in plants, accounting for up to 80 per cent of the total phosphorus [30,31]. Phytic acid has been found in cassava root [32] and cocoyam tuber [13] up to levels of 62.4 and 1.75g/100g, respectively. Josefsen et al, [33] reported that the negatively charged phosphate in phytic acid strongly binds to metallic cations (e.g.…”

Opinion of the Scientific Panel on contaminants in the food chain [CONTAM] related to cyanogenic compounds as undesirable substances in animal feed

“…In this well documented study the authors state that the inclusion of cassava root meal in chick diets can result in watery excreta, which cause litter management problems and, therefore, might limit the use of the meal in some poultry production systems. Furthermore they found an apparent association of the intake ratio of water to food with the cyanogen content of the diet and noted that this may suggest that water intake is related to the mechanisms of cyanide toxicity or the detoxification of cyanogenic glucosides (Panigrahi et al, 1992). This study together with studies of Tewe (1984) and Gomez et al (1988) are reviewed by Garcia and Dale (1999), a review allowing the following conclusions:…”

“…However, once again, only few of them provide data on the content of cyanogenic compounds, although they do sometimes investigate the effect of adding sulfur in the form of elementary sulfur or as Na 2 SO 4 to ensure optimal conditions for in vivo detoxification (metabolism to thiocyanate) of ingested cyanide and cyanogens (Gowdh et al, 1990). Panigrahi et al (1992) found that cassava root meal of less than 40 mg total cyanide per kg meal can be fed to broiler chicks at 500 g/kg of total diet without any adverse effects. In this well documented study the authors state that the inclusion of cassava root meal in chick diets can result in watery excreta, which cause litter management problems and, therefore, might limit the use of the meal in some poultry production systems.…”

Exposição cianídrica em suínos: uma abordagem dos parâmetros toxicocinéticos utilizando o tiocianato como biomarcador

“…Por outro lado, há vários trabalhos na literatura, relatando que a exposição prolongada ao cianeto, em baixas concentrações, pode ocasionar quadros de toxicidade crônica. De fato, em humanos, foi comprovada a associação entre a exposição crônica ao cianeto na etiologia de alguns distúrbios neurológicos, tais como neuropatia atáxica tropical 7 , konzo 8 , neuropatia retrobular da anemia perniciosa 9 e atrofia óptica de Leber 10,11 . Na criação animal, a ingestão crônica do cianeto tem sido associado a diversas doenças, como a cistite e ataxia enzoótica, uma síndrome caracterizada pela presença de degeneração walleriana da substância branca da medula espinhal e de degeneração de pedúnculos cerebrais e cerebelares 12,13,14 .…”