Safety and Transfer Study: Transfer of Bromoform Present in Asparagopsis taxiformis to Milk and Urine of Lactating Dairy Cows

Abstract

Enteric methane (CH4) is the main source of greenhouse gas emissions from ruminants. The red seaweeds Asparagopsis taxiformis (AT) and Asparagopsis armata contain halogenated compounds, including bromoform (CHBr3), which may strongly decrease enteric CH4 emissions. Bromoform is known to have several toxicological effects in rats and mice and is quickly excreted by the animals. This study investigated the transfer of CHBr3 present in AT to milk, urine, feces, and animal tissue when incorporated in the diet of dairy cows. Twelve lactating Holstein-Friesian dairy cows were randomly assigned to three treatment groups, representing the target dose (low), 2× target dose (medium), and 5× target dose (high). The adaptation period lasted seven days, and subsequently cows were fed AT for 22 days maximally. The transfer of CHBr3 to the urine at days 1 and 10 (10–148 µg/L) was found with all treatments. On day 1, CHBr3 was detected in the milk of most cows in the low and medium treatment groups (9.1 and 11 µg/L, respectively), and detected in the milk of one cow in the high treatment group on day 9 (35 µg/L). Bromoform was not detected in milk and urine at day 17, nor at concentrations above the detection limit in feces and collected animal tissues. Two animals (low) were sacrificed, and their rumen wall showed abnormalities. Upon histological examination, signs of inflammation became visible. Animals regularly refused the feed or distinctively selected against AT. In conclusion, within the confines of the present experiment, CHBr3 does not accumulate in animal tissue, but can be excreted in urine and milk.

Targeted and Untargeted Metabolic Profiling to Discover Bioactive Compounds in Seaweeds and Hemp Using Gas and Liquid Chromatography-Mass Spectrometry

“…The anti-methanogenic effect was attributed to halogenated compounds such as bromoform, dibromochloromethane and dibromethane [ 10 , 13 ]. The toxicity and ozone degrading properties of halocarbons are well known, and there are both health and environmental concerns related to the use of Asparagopsis taxiformis as a feed additive [ 14 ]. Brown seaweeds have also shown anti-methanogenic potential [ 5 , 6 ].…”

Current Perspectives on Achieving Pronounced Enteric Methane Mitigation From Ruminant Production

“…Palatability aspects might contribute to explain the interaction, as low palatability has been reported in some studies with Asparagopsis spp. (Muizelaar et al, 2021;Stefenoni et al, 2021), and in contrast, no palatability issues were found with 3-NOP (Lee et al, 2020).…”

How necessary and feasible are reductions of methane emissions from livestock to support stringent temperature goals?

“…The role of bromoform and bromochloromethane as active ingredients in Asparagopsis raises challenges from a regulatory and market acceptability perspective, given that both substances are confirmed animal carcinogens and probable/possible human carcinogens. Animal trials have detected residues in urine and milk [90], but no detrimental effects on meat quality [91]. There are also open questions regarding palatability to livestock, animal health and the ability to produce and supply seaweed at a large scale, especially to extensively grazed livestock [88][89][90]92].…”

“…Animal trials have detected residues in urine and milk [90], but no detrimental effects on meat quality [91]. There are also open questions regarding palatability to livestock, animal health and the ability to produce and supply seaweed at a large scale, especially to extensively grazed livestock [88][89][90]92].…”