Slow-release urea partially replace soybean in the diet of Holstein dairy cows: Intake, blood parameters, nutrients digestibility, energy utilization, and milk production

Hani M. El-Zaiat*, Ahmed E. Kholif, Ibrahim M. Khattab, Sobhy M.A. Sallam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The present experiment aimed to evaluate the partial replacement of soybean with slow-release urea (Optigen 1200™) in the diet of lactating cows for 84 d. Three-hundred multiparous lactating Holstein (635 ± 25 kg of body weight, BW) cows were stratified by live body weight; parity and previous milk production were randomly assigned into two experimental groups with 150 cows per each treatment. In the control treatment, 25 g soybean meal was replaced by 5.7 g slow-release urea for 84 d. Optigen treatment did not affect feed intake, daily milk production, milk composition, or milk (feed) efficiency; however, increased (P<0.01) total BW gain and daily BW gain. Optigen treatment increased (P<0.01) the digestibility of crude protein and neutral detergent fiber. Optigen treatment increased (P<0.01) estimated N balance, milk urea-N, and net energy (NE) for gain. Without affecting blood total protein, creatinine, urea-N, triglycerides, glucose, β-hydroxybutyrate, or non-esterified free fatty acids, Optigen treatment increased the concentrations of blood albumin and cholesterol compared to the control (P<0.05). In conclusion, slow-release urea could replace soybean meal in ruminant diets with no adverse effects on feed intake, nitrogen utilization, or digestibility; however, improve the total tract digestibility of fiber and crude protein in cows.

Original languageEnglish
Article number0053
JournalAnnals of Animal Science
Publication statusAccepted/In press - 2021
Externally publishedYes


  • And composition
  • Milk production
  • Nitrogen balance
  • Nitrogen excretion
  • Nitrogen metabolism
  • Slow-release urea

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology

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