December 7, 2010

Irish research shows that benzoic acid reduces nitrogen excretion

According to Irish scientists who studied the effect of benzoic acid concentration on nitrogen metabolism, manure ammonia, and odour emissions in finishing pigs, benzoic acid reduces nitrogen excretion.

A complete randomised block design experiment was conducted to investigate the effects of benzoic acid inclusion level on nitrogen (N) metabolism, and manure ammonia (NH3) and odour emissions in finishing pigs.

Sixteen boars were assigned to one of four dietary treatments (T) varying in benzoic acid concentration. They are (T1) 0 g/kg (as fed), (T2) 10 g/kg, (T3) 20 g/kg, and (T4) 30 g/kg.

Animals were housed in individual metabolism crates and feed was provided ad libitum. All diets were formulated to have similar concentration of digestible energy and ileal digestible lysine with benzoic acid replacing wheat in the diet.

There was a linear decrease in NH3 emission, as the dietary benzoic acid concentration increased (141.4 mg/g versus 40.5 mg/g N intake (S.E.M. 12.1) over the 240-h storage period).

However, there was no effect of benzoic acid on odour concentration.

Urinary nitrogen (N) excretion, total N excretion, and the urinary-to-faecal N ratio were linearly reduced with increasing benzoic acid inclusion.

Furthermore, N retention increased linearly as benzoic acid concentration increased from 0 g/kg to 30 g/kg in the diet.

In conclusion, the inclusion of benzoic acid in the diet of finishing pigs has the potential to reduce total and urinary N excretion and the urinary-to-faecal N ratio.

This was mirrored by reductions in manure NH3 emissions in the benzoic acid supplemented treatments.