Comparison of Biogenic Amines and Mycotoxins in Alfalfa and Red Clover Fodder Depending on Additives

In the production of fermented feed, each crop can be contaminated with a variety of microorganisms that may produce natural pollutants. Biogenic amines, mycotoxins, and undesirable organic acids can decrease health feed safety. The aim of this study was to compare the counts of microorganisms, levels of biogenic amines, and the mycotoxins in forage legumes, and also to compare the occurrence of microorganisms and levels of mycotoxins in green fodder and subsequently produced silage and the influence of additives on the content of natural harmful substances in silage. The experimental plot was located in Troubsko and Vatín, in the Czech Republic. Two varieties of Medicago sativa and one variety of Trifolium pratense were compared. Green fodder and subsequently produced silage reaching up to 23% of dry matter were evaluated and prepared using a bio-enzymatic additive and a chemical additive. Green fodder of Medicago sativa was more contaminated by Enterococci than Trifolium pratense fodder. The obvious difference was determined by the quality of silage leachate. The silage prepared from Medicago sativa fodder was more contaminated with butyric acid. Fungi were present in higher counts in the anaerobic environment of green fodder and contaminated it with zearalenone and deoxynivalenol. Lower counts of fungi were found in silage, although the zearalenone content did not change. Lower content of deoxynivalenol was detected in silage, compared with green fodder. Silages treated with a chemical additive were found not to contain butyric acid. Lower ethanol content was determined, and the tendency to reduce the risk of biogenic amines occurrence was evident. The additives proved to have no influence on the content of mycotoxins.

The voluntary intake by cattle of four silages differing in dry matter content

Herbage from the same timothy/meadow fescue/white clover sward was ensiled at four different dry matter contents. The resulting silages had dry matter contents of 19·0, 27·3, 32·3 and 43·2%, the dry matter content increasing with the length of the wilting period. An experiment was carried out to determine the voluntary intake of the silages. Each silage was given to 7 animals individually, the mean live weight of these being 334 kg.

Although the silages made from wilted herbage were lower in digestibility than that made from unwilted herbage, wilting increased dry matter intake and metabolizable energy (ME) intake. The mean daily intakes of digestible organic matter were 53·0, 58·1, 59·6 and 59·6 g/kgW0·73, for silages of increasing dry matter content. The corresponding ME intakes, expressed as a multiple of the ME requirement for maintenance, were 1·17, 1·29, 1·30 and 1·28. The percentage of acetic acid in the silage dry matter was significantly (r= −0·56) and linearly related to voluntary intake. The relationship between lactic acid concentration and voluntary intake was significantly curvilinear (r= 0·48).

The effect of protein degradation products in grass silages on feed intake and intake behaviour in sheep

The effects of NH3 and amines on grass-silage intake, intake behaviour and rumen characteristics were studied in sheep. From a single sward, two direct-cut grass silages were prepared, either untreated (WAS) or with 4·51 formic acid/tonne (FAS). Four experimental diets: WAS, FAS, FAS with addition of 2·9 g NH3/kg DM (FAS + N) and FAS with 2·8 g amines/kg DM (FAS + A), were offered ad lib. once daily to four rumen-cannulated wethers in a 4 × 4 Latin square design. Daily DM intake (DMI) tended to be influenced by dietary treatment (P = 0·09). Compared with FAS, DMI was lower for WAS. Addition of NH3 did not alter DMI, whereas amine addition slightly lowered daily DMI. Reduced DMI resulted from lower intake rates during both the principal meal and the subsequent small meals. Lower initial intake rate during the principal meal suggested reduced palatability of WAS and FAS + A. Amines and NH3, however, did not influence chewing efficiency. No treatment effects were observed on total rumen pool size, DM and neutral-detergent fibre content. Furthermore, NH3, and amines did not alter rumen pH, NH3, and volatile fatty acid concentrations to the extent that they could act on chemostatic intake regulation. Amine addition, however, lowered osmolality of the rumen liquid. No treatment effects on rumen motility were observed. In conclusion, daily DMI was not reduced by the addition of NH3, suggesting that NH3per se is not the causal factor in the negative correlations between silage NH3 content and intake observed by other authors. Amines, however, tended to reduce DMI only by their effect at the oro-pharyngeal level of intake control.

Biogenic amines in silage. 1. The occurrence of biogenic amines in silage

In laboratory silages made from orchardgrass, red clover and oats, significant levels of toxic biogenic amines were found. The most widespread were putrescine and cadaverine, concentrations of spermidine, spermine and histamine were ten times lower on average. Of the amines considered, putrescine content seems to be the most sensitive indicator of the extent of putrefaction in silages. A relationship between the putrescine contents and the degree of proteolysis was found. The biogenic amine content is closely connected with both the variety of crop ensiled and even more so with the method and the efficiency of preservation. Neither the application of formic acid nor wilting suppressed the formation of any of the amines in silages selectively. Formic acid suppressed the total concentration of amines to 23% as compared with controls. The highest levels of amines were found in orchardgrass and oat silages; smaller amounts were detected in clover silages. In the case of very poorly preserved silage 100-150 g of toxic amines can be consumed by a cow in a day. This could have a deleterious effect on the physiological condition and the performance of livestock.