Effects of dietary replacement of urea with encapsulated nitrate and cashew nut shell liquid on nutrient digestibility, nitrogen balance, and carcass characteristics in growing lambs

H. M. El-Zaiat*, R. C. Araujo, H. Louvandini, H. O. Patiño, A. L. Abdalla

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Nitrate (NO3¯) salts can be used as an alternative to urea in ruminant diets. The objective of this study was to investigate the effects of using encapsulated nitrate (EN) alone or combined with cashew nut shell liquid (EN + CNSL) to replace urea (UR) on intake and nutrient digestibility, nitrogen (N) balance, microbial nitrogen (MN) supply, carcass attributes, and meat quality of growing lambs. Eighteen Santa Inês male lambs (36.2 ± 5 kg of body weight; mean ± SD) were allocated individually to metabolic crates and fed a backgrounding diet with a 60:40 concentrate to forage ratio for 92 days. Lambs were assigned to a randomized complete block design with 6 blocks and 3 experimental diets: UR, 15 g urea/kg dry matter (DM); EN replacing UR at 45.1 g/kg DM; and EN + CNSL replacing UR at 45.1 g/kg DM. After finishing the digestibility and N balance trials, all lambs were fasted for 18 h, weighed, and then slaughtered. The dry matter intake (DMI) and nutrient digestibility were similar (P > 0.05) among treatments. The addition of EN or EN + CNSL tended to increase urinary NO3¯ excretion (P = 0.056) and NO2¯ excretion (P < 0.001). Compared to the UR diet, lambs fed EN or EN + CNSL diets decreased (P = 0.011) urinary UR concentrations. No differences (P> 0.05) in purine derivative excretion or daily MN supply were observed among treatments. The addition of EN or EN + CNSL did not affect (P > 0.05) hot or chilled carcass yields, chilling weight losses, or carcass pH. No differences (P > 0.05) in 12thrib longissimus muscle (LM) area, fat thickness, or color were observed. Fresh LM samples indicated no effects (P > 0.05) of EN or EN + CNSL on NO3¯ concentrations, and NO2¯ in LM samples was not detected. In conclusion, EN could be used as a replacement for UR in the diets of growing lambs with no adverse effects on nutrient digestibility or fresh meat quality.

Original languageEnglish
Article number114515
JournalAnimal Feed Science and Technology
Publication statusPublished - Aug 2020


  • Carcass attributes
  • Digestibility
  • Encapsulated nitrate
  • Growing lambs
  • Nitrogen utilization

ASJC Scopus subject areas

  • Animal Science and Zoology

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