Productivity, Profitability and Nitrogen Utilisation Efficiency of Two Pasture-Based Milk Production Systems Differing in the Milking Frequency and Feeding Level

Martín Correa-Luna,Elodie Ruelle,Deirdre Hennessy,Daniel Donaghy,Laurence Shalloo,Peter Kemp,Nicolás López-Villalobos

doi:10.3390/su13042098

Martín Correa-Luna, Elodie Ruelle + Show 5 more

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https://doi.org/10.3390/su13042098

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Abstract

The aim of this study was to model the productivity, profitability and the nitrogen (N) utilisation efficiency (NUE) of two spring-calving pasture-based milk production systems differing in milking frequency and intensification levels in New Zealand. For this purpose, physical performance data from a low-intensity production system where cows were milked once per day (OAD-LI) and from a high-intensity production system where cows were milked twice per day (TAD-HI) were employed. OAD-LI cows were milked once-daily with a stocking rate (SR) of 2.1 cows/ha and fed diets with low supplementation (304 kg pasture silage/cow) with applications of 134 kg N fertiliser/ha and TAD-HI cows were milked twice-daily with a SR of 2.8 cows/ha and fed diets of higher supplementation (429 kg pasture silage and 1695 kg concentrate/cow) with applications of 87 kg N fertiliser/ha. The Moorepark Dairy System Model was used to evaluate production, economic performance and N balance on an annual basis. Despite the higher feed costs of TAD-HI as more supplementation was utilised, profitability per hectare was 16% higher because more cows were milked with a higher milk yield per cow (milking frequency) when compared to OAD-LI. At the cow level, the NUE was higher in TAD-HI (30% vs. 27%) reflecting the better balanced diet for energy and crude protein and higher milk yields as a result of milking frequency. At the farm scale the NUE was higher (38% vs. 26%) in the TAD-HI due to the losses associated with the imported feed being excluded and higher N captured in milk. These results suggest that milking frequency, the use of feed supplementation and application of N fertiliser as management tools on grazing dairy systems affect productivity, profitability and N balance. Further studies are required to find optimal stocking rates in combination with the use of supplementary feed and N fertiliser application that maximize milk production and profitability for OAD and TAD milking production systems but minimize N losses.

Highlights

The present research investigated the differences in productivity, profitability and some environmental consequences between two contrasting pasture-based dairy farming systems of New Zealand differing in milking frequency and intensification level
N surplus, but the N utilisation efficiency (NUE) was better in the TAD high intensity production system (TAD-HI) production system reflecting a more balanced diet in terms of crude protein (CP) and energy
This represented a lower NUE in OAD low intensity production system (OAD-LI) and increased the N available for loss

Summary

Introduction

Sustainability 2021, 13, 2098 levels that regularly exceed milk production requirements [1,4] This results in more N excreted and a decrease in N utilisation efficiency (NUE) at the cow level, defined in this case as N captured in milk and meat as a proportion of total N intake. Considering that in these systems cows are raised outdoors all year round, most of their excreta is returned to pasture, and this increases the nitrate-N levels in soil solution and groundwater. This is an important environmental problem, as well as being wasteful in terms of utilisation of plant nutrients [5,6]

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