Effect of reducing rumen undegradable protein and protected lysine and methionine supplementation on dry matter intake, milk yield and composition and nutrient digestibility of Holstein cows in early lactation

Articles in Press

Document Type : Research Paper

Authors

1 Department of Animal Science, Faculty of Agriculture, Ilam University, Ilam, Iran

2 Animal Sciences Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO). Karaj. Iran

Abstract

The aim of this study was to investigate the effect of reducing level of rumen undegradable protein (RUP) and rumen-protected lysine and methionine supplementation on dry matter intake (DMI), milk yield and composition and total tract nutrients digestibility of dairy cows in early lactation. Twelve multiparous (2nd parity) Holstein dairy cows were used in replicated 4×4 Latin square design (4 treatments in 4 periods). Each period lasted 21 d with 14 d of experimental diets adaptation and 7 d of data recording and sample collection. The experimental diets included 1- diet containing 17.32% crude protein (CP) without rumen-protected lysine (RPL)and methionine (RPM) supplementation (CP17.32-NoRPL-NoRPM), 2- diet containing 16.08% CP and 0.045% RPM (CP16.08-RPM0.045%), 3- diet containing 15.18% CP and 0.075% RPM (CP15.18-RPM0.075%), and 4- diet containing 14.2% CP, 0.105% RPM, and 0.037% RPL (CP14.2-RPM0.105%-RPL0.037%). Results showed that the lowest DMI was observed in cows fed CP14.2-RPM0.105%-RPL0.037% and CP15.18-RPM0.075% diets compared to others (P<0.05). Milk yield, 4% fat corrected milk, energy corrected milk and milk component production were not affected by the experimental diets (P<0.05). Experimental diets did not affect total tract apparent digestibility of dry matter (DM) and organic matter (OM) (P<0.05). The highest total tract apparent digestibility of CP were observed in cows fed CP17.32-NoRPL-NoRPM (P<0.05). Overall, feeding CP15.18-RPM0.075% diet improved productive performance of Holstein dairy cows in early lactation.

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Iranian Journal of animal Science

Articles in Press, Accepted Manuscript
Available Online from 26 August 2025

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History

  • Receive Date: 09 April 2025
  • Revise Date: 18 May 2025
  • Accept Date: 07 June 2025

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