The potential of grass-based, dairy-beef heifer systems
Dr. Ellen Fitzpatrick presented findings on low-input, high-output, grass-based, dairy-beef heifer systems at the Teagasc National Beef Conference 2023.
Ellen highlighted the importance of reducing greenhouse gas emissions and the increasing number of heifers, particularly from the dairy herd, due to technologies like sexed semen. The sector aims to reduce the age of slaughter by up to three months and reduce chemical nitrogen use by 20%.
Ellen's research aims to determine if a predominantly grass-based diet can reduce slaughter age and support high levels of carcass output. The research also examines the interaction between nitrogen and the system, focusing on the use of perennial ryegrass swards.
Ellen emphasised the potential of grass-based, dairy-beef heifer systems for high carcass output per hectare. Rising costs of fertilisers, feed and fuel highlighted the importance of efficient utilisation of grass. Perennial ryegrass, commonly sown in Ireland, relies on chemical nitrogen for growth, raising environmental concerns and costs. The study explored alternatives, including clover-based and multispecies swards, aiming to reduce chemical fertiliser use.
The study compared heifers consuming herbage from perennial ryegrass (PRG) only swards, PRG + Clover (CLOVER) swards, and multispecies swards (MSS). Despite a 75kg/ha reduction in annual chemical nitrogen (N) application to CLOVER and MSS treatments, all three pasture types achieved similar carcass weights. Incorporating legumes and herbs into pasture reduced the need for chemical fertiliser nitrogen and concentrate supplementation.
Additionally, despite varying nitrogen applications, similar herbage production was observed. Clover-based swards and multispecies swards showed potential in reducing the need for chemical nitrogen. The study evaluated herbage production, with clover content peaking in July for CLOVER and MSS pastures. The average herbage dry matter concentration was lowest for MSS, intermediate for CLOVER, and highest for PRG.
In terms of animal performance, the study indicated that dairy-beef heifers on MSS pastures performed well as calves, while those on CLOVER performed best as yearlings. MSS pastures showed a lifetime daily live weight gain advantage over PRG. A greater proportion of heifers on CLOVER and MSS pastures were slaughtered off pasture, reducing indoor finishing concentrate requirements and feed costs. Despite requiring more housing and higher concentrate inputs, PRG heifers were leaner.
The study concluded that reduced chemical nitrogen use, improved lifetime average daily gain, and carcass weight are crucial for enhancing profitability and environmental sustainability in pasture-based dairy-beef production. Incorporating clover into perennial ryegrass swards offers a potential blueprint for optimising efficiency and meeting climate targets.
Summary
- Dairy-beef heifers consuming herbage from perennial ryegrass (PRG)-only swards, PRG + Clover (CLOVER) swards, and multispecies swards (MSS) achieved carcass weights of 243, 250 and 249 kg, at 19.6, 19.2, and 19.2 months of age, respectively.
- Similar herbage production was achieved for all three pasture types, despite a 75 kg/hectare reduction in annual chemical nitrogen (N) application to the CLOVER and MSS treatments.
- Incorporating legumes and herbs into pasture reduces the requirement for chemical fertiliser nitrogen and concentrate supplementation in grassbased dairy-beef heifer systems.
Download the full paper: Low-input high-output grass-based dairy-beef heifer systems
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