Table 2.

Studies analysing effects of bromoform/halogenated compounds on CH₄ emissions in vitro and in vivo

Compound	Type of study	Animal	Basal diet	Dosage	Impact on CH4 emissions	References
Bromoform	In vitro (batch fermentation)	Brahman steers cattle	Rhodes grass	2 concentrations tested: 1 µmol/L and 5 µmol/L	Addition of 1 µmol/L reduced CH4 by 77% and 5 µmol/L reduced CH4 by > 99% compared to basal substrate-only control	[13]
Bromoform	In vitro (gas production recorder)	Lactating Swedish Red cows	Timothy grass, rolled barley, rapeseed in ratio 545:363:92 g/kg diet dry matter	2 dosage rates: 1.5 mg/g dry matter, and 3 mg/g dry matter	95% reduction in CH4	[39]
Bromoform Dibromochloromethane Bromochloroacetic acid Dibromoacetic acid	In vitro (Ankom system)	Brahman steers cattle	Rhodes grass hay	4 concentrations tested: 1 µmol/L, 5 µmol/L, 10 µmol/L, and 25 µmol/L	In the case of bromoform and dibromochloromethane, CH4 production completely inhibited at concentrations ≥ 5 µmol/L In the case of bromochloroacetic acid and dibromoacetic acid, no effect on CH4 production observed	[71]
Bromochloromethane	In vivo	Murciano-Granadina lactating goats	Alfalfa hay with 600 g/d concentrates	0.3 g of BCM/100 kg body weight BCM administered 2 equal doses per day from parturition to 2 weeks postweaning	33% reduction in CH4	[29]
Bromochloromethane	In vivo	Brahman-crossbred steers	Rhodes grass and 1 kg/d proprietary grain pellets	0.3 g of BCM/100 kg body weight	30% reduction in CH4	[31]
Bromochloromethane	In vitro (batch and continuous fermentation)	Non-lactating Friesian-Holstein cattle	Batch: hay Continuous: 20 g/d hay	Batch: 5 µmol/L and 10 µmol/L tested Continuous: 5 µmol/L	Batch: 89%–94% reduction of CH4 at both concentrations tested Continuous fermentation resulted in 85%–90% CH4 reduction	[75]
Bromochloromethane	In vivo	Japanese native (Shiba) goats	50% timothy gras 50% concentrates	Animals sequentially adapted to low, medium, and high doses of BCM. Low dose: 0.5 g/100 kg live weight Medium dose: 2 g/100 kg live weight High dose: 5 g/100 kg live weight	Low dose: 5% reduction in CH4 Medium dose: 71% reduction in CH4 High dose: 91% reduction in CH4	[76]