Nitrogen balance, ammonia and odor emissions in growing pigs fed reduced protein diets

Harold Anindo Rachuonyo, Michael Ellis, Diego Braña Varelab, Stanley Evan Curtis, José Antonio Cuarón Ibargüengoytia

Research output: Contribution to journalArticlepeer-review


The effect of reducing the crude protein (CP) levels in diets fed to growing pigs, was evaluated in two experiments, each using two diets formulated to contain either a normal (19%) or a reduced CP level (14%), with constant levels for standardized ileal digestible lysine (0.85%), and metabolizable energy (3.37 Mcal ME/kg). Exp I measured the N balance of pigs (n= 24) initially weighing 17.7±1.29 kg, while Exp II used 24 pigs from 17.9±0.76 kg to assess aerial ammonia (NH3) emissions and odor levels in dynamic airflow chambers for 21 d. In Experiment I, N intake (26.6 %), urinary N (56 %), and total N excretion (41 %) were lower (P<0.001) for the reduced CP level, while fecal N excretion was similar (P>0.4). In Experiment II, reducing dietary CP did not affect (P>0.10) growth performance, but tended to reduce (P<0.10) manure pH (6.71, normal and 6.21±0.186 for reduced CP) and NH3 emissions, which were diminished after d-9 trial (dietary CP and days in the experiment interacted, P<0.001). Odor levels measured on d-14 and 21 of the study, assessed by olfactometry, did not differ between treatments (512 and 540±115.6 threshold units for the reduced and normal CP diets), but increased (P<0.01) with time on feed (440 and 612 ± 111.3 threshold units on d-14 and 21, respectively). These results suggest that each one percentage unit reduction in dietary CP (combined with the appropriate AA supplementation) lowers N excretion (by 8 %) and NH3 emissions from manure (by 15 %), with no effect on manure odor.

Original languageEnglish (US)
Pages (from-to)119-136
Number of pages18
JournalRevista Mexicana De Ciencias Pecuarias
Issue number2
StatePublished - Apr 1 2015


  • Ammonia
  • Nitrogen balance
  • Odor
  • Pig manure

ASJC Scopus subject areas

  • Animal Science and Zoology
  • General Veterinary


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