Milk production per cow and per hectare of spring-calving dairy cows grazing swards differing in Lolium perenne L. ploidy and Trifolium repens L. composition

B McClearn, T J Gilliland, L Delaby, C Guy, M Dineen, F Coughlan, B McCarthy

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Grazed grass is the cheapest feed available for dairy cows in temperate regions; thus, to maximize profits, dairy farmers must optimize the use of this high-quality feed. Previous research has defined the benefits of including white clover (Trifolium repens L.) in grass swards for milk production, usually at reduced nitrogen usage and stocking rate. The aim of this study was to quantify the responses in milk production of dairy cows grazing tetraploid or diploid perennial ryegrass (Lolium perenne L.; PRG) sown with and without white clover but without reducing stocking rate or nitrogen usage. We compared 4 grazing treatments in this study: tetraploid PRG-only swards, diploid PRG-only swards, tetraploid with white clover swards, and diploid with white clover swards. Thirty cows were assigned to each treatment, and swards were rotationally grazed at a farm-level stocking rate of 2.75 cows/ha and a nitrogen fertilizer rate of 250 kg/ha annually. Sward white clover content was 23.6 and 22.6% for tetraploid with white clover swards and diploid with white clover swards, respectively. Milk production did not differ between the 2 ploidies during this 4-yr study, but cows grazing the PRG-white clover treatments had significantly greater milk yields (+596 kg/cow per year) and milk solid yields (+48 kg/cow per year) compared with cows grazing the PRG-only treatments. The PRG-white clover swards also produced 1,205 kg of DM/ha per year more herbage, which was available for conserving and buffer feeding in spring when these swards were less productive than PRG-only swards. Although white clover is generally combined with reduced nitrogen fertilizer use, this study provides evidence that including white clover in either tetraploid or diploid PRG swards, combined with high levels of nitrogen fertilizer, can effectively increase milk production per cow and per hectare.

Original languageEnglish
Pages (from-to)8571-8585
Number of pages15
JournalJournal of Dairy Science
Volume102
Issue number9
Early online date10 Jul 2019
DOIs
Publication statusEarly online date - 10 Jul 2019

Bibliographical note

Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Keywords

  • Animal Feed/analysis
  • Animals
  • Cattle/physiology
  • Dairying/methods
  • Diet/veterinary
  • Female
  • Fertilizers/analysis
  • Lactation/physiology
  • Lolium
  • Milk
  • Nitrogen/analysis
  • Pregnancy
  • Seasons
  • Trifolium

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  • Student Theses

    Effect of Lolium perenne L. ploidy, Trifolium repens L. inclusion and cow breed on the productivity and profitability of pasture-based, spring-milk systems

    Author: McClearn, B., Dec 2020

    Supervisor: Gilliland, T. (Supervisor) & Meharg, A. (Supervisor)

    Student thesis: Doctoral ThesisDoctor of Philosophy

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