Increasing dietary concentrate level reduced methane emission as a proportion of feed intake and milk yield, but breed had no effect on methane output
Take Home Message: To reduce methane output per kg milk feed higher levels of concentrates, but there is little affect of changing cow breed.
Increasing dietary concentrate level reduced methane emission as a proportion of feed intake and milk yield. But cow breed (Holstein compared to Jersey-Holstein) had no significant effect on methane output as a proportion of feed intake or energy corrected milk yield.
These were just two or the findings of a study carried out at Hillsborough’s AFBI to evaluate the effects of level of concentrate supplementation and cross-breeding of Holstein cows with Jersey sires on CH4 production.
“Enteric fermentation in ruminants is an important source of methane (CH4) production and in the UK ruminants contribute approximately 20% of all CH4 emission, with most arising from cattle,” AFBI’s Tianhai Yan told delegates at this year’s British Society of Animal Science annual conference.
“This presents a considerable challenge for the dairy industry in the battle against global warming, and reduced CH4 emission is likely to be a major target for government policy within the next few years,” he added, clarifying the rational behind his team’s work.
Eight Holstein and eight Jersey-Holstein first-lactation cows were used in a four-period (6 weeks/period) change-over study. Each breed was offered ad-lib mixed diets of grass silage with two different levels of concentrates (0.30kg/kgDM and 0.70kg/kgDM)
The cows were housed in cubicle accommodation and then transferred to metabolism units for an 11 day period. Faeces and urine outputs were collected from day three to eight in metabolism units. From day nine to 11, cows were placed in indirect respiration calorimeter chambers with gaseous exchange measured during the final 48 hours.
Data analysis revealed that there was no significant interaction between cow breed and concentrate level on any parameter. On average across the two concentrate levels, cow breed had no significant effect on live weight or milk yield, but Jersey-Holstein cows had higher body condition scores, DM intake and fat corrected milk yield.
“Total CH4 output and CH4/milk yield were higher with Jersey-Holstein cows, while cow breed had no significant effect on CH4/DM intake, CH4-E (CH4 energy)/GE intake or CH4/corrected milk yield,” said Dr Yan. “On average across the two breeds, cows offered the high concentrate diet had higher DM intake, milk yield and corrected milk yield, but lower CH4/DM intake, CH4/milk yield, CH4/corrected milk yield and CH4-E/GE intake.”
When relating CH4/corrected milk yield to corrected milk yield and CH4/DM intake to DM intake with a common constant, Holstein cows had a marginally larger coefficient in the former relationship (with corrected milk yield ranging from 13 to 30 kg/d) and a slightly smaller coefficient in the latter relationship.
“These linear relationships indicate that cross breeding had little effect on proportional CH4 production,” concluded Dr Yan.
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