Pasture characteristics of Italian ryegrass and milk production under different management strategies

Marcolino Frederico Miguel,Steben Crestani,Tereza Cristina Moraes Genro,Henrique Mendonça Nunes Ribeiro Filho,Fabiana Da Rocha Ramos

doi:10.1590/s0100-204x2012000600018

Marcolino Frederico Miguel, Steben Crestani + Show 3 more

Open Access

https://doi.org/10.1590/s0100-204x2012000600018

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Abstract

The objective of this work was to assess the effects of the sward structure of Italian ryegrass (Lolium multiflorum), during the first grazing cycle, on its morphological and bromatological characteristics throughout the growing season, and on the performance of dairy cows. The treatments consisted of two structures obtained as a function of canopy-light interception: high-light interception (HLI) and low-light interception (LLI), with different pre-grazing heights in the first grazing cycle. Pasture was managed under rotational grazing with a herbage allowance not below 30 kg dry matter (DM) per cow per day. Three grazing cycles, with a grazing interval of 30 days, were evaluated. Pre-grazing herbage mass was greater (2,240 vs. 1,656 kg ha-1 DM), but the proportion of leaf blades was smaller (0.35 vs. 0.43) for HLI swards. Neutral detergent fiber (NDF) content and organic matter digestibility (OMD) were similar between treatments in the first grazing cycle, but in the second and third ones NDF was greater, and OMD lower, for the HLI swards. Milk yields were greater for cows grazing LLI swards (19.4 vs. 21.1 kg per day). Initial grazing with 90% of light interception promotes greater nutritional value in the subsequent cycles.

Highlights

The efficiency of production systems for grazing animals is a function of the ingested herbage quality and quantity, which are strongly correlated to the adopted forage species and management practices (Hopkins & Wilkins, 2006)
Little is still known about the effects of aerial biomass availability before the first grazing cycle on milk yield during the growing cycle of the most common winter forage species, such as Italian ryegrass (Lolium multiflorum Lam.), in subtropical climate regions
The objective of this work was to assess the effects of the sward structure of Italian ryegrass (Lolium multiflorum) during the first grazing cycle on its morphological and bromatological characteristics throughout the growing season, and on the performance of dairy cows

Summary

Introduction

The efficiency of production systems for grazing animals is a function of the ingested herbage quality and quantity, which are strongly correlated to the adopted forage species and management practices (Hopkins & Wilkins, 2006). Among these, are the hasting date of first grazing (O’Donovan et al, 2004; Kennedy et al, 2006, 2007) and the increased defoliating frequencies with reduced intervals between grazing cycles and increasing number of cycles (McEvoy et al, 2009; Curran et al, 2010; Roca‐Fernandez et al, 2011) In both cases, milk yield can increase up to 2.0 kg per cow and more than 1,300 kg ha‐1. Little is still known about the effects of aerial biomass availability before the first grazing cycle on milk yield during the growing cycle of the most common winter forage species, such as Italian ryegrass (Lolium multiflorum Lam.), in subtropical climate regions. It is relevant to know if Italian ryegrass pastures with larger proportion of leaf blades at the beginning of the first grazing cycle would allow for the maintenance of this parameter throughout sucessive cycles and if it has positive consequences on herbage intake and fat‐corrected milk yields

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