Application of a Simulation Model for Dairy Cattle Production Systems Integrated with Forage Crop Production: the Effects of Whole Crop Rice Silage Utilization on Nutrient Balances and Profitability

K Kikuhara,H Hirooka

doi:10.5713/ajas.2009.80099

Abstract

In Japan, since rice consumption has been decreasing with the westernization of Japanese eating habits, surplus paddy fields have been increasing. If these surplus paddy fields can be utilized for forage rice production as feed for animal production and excretions (feces and urine) from animal production can be applied to the paddy fields as manure, then the problems of surplus paddy fields and excretions from animal production may be solved, and the environment kept sustainable. The objectives of the present study were to apply a bio-economic model to dairy and forage rice integration systems in Japan and to examine the merit of introducing whole crop rice silage (WCRS), as well as economic and environmental effects of various economic and management options in the systems. Five simulations were conducted using this model. The use of WCRS as a home-grown feed increased environmental loads and decreased economic benefit because of the higher amount of purchased feed, when compared to the use of typical crops such as maize, alfalfa and timothy silage (simulation 1). Higher economic benefits from higher forage rice yields and higher milk production of a dairy cow were obtained (simulations 2, 3). There were no economic and environmental incentives for utilizing crude protein (CP) rich WCRS, because an increase in the CP content in WCRS led to the use of more chemical fertilizers, resulting in high production costs and nitrogen outputs (simulation 4). When evaluated under the situation of a fixed herd size, increasing forage rice yields decreased the total benefit of the production, in spite of the fact that the amount of subsidies per unit of land increased (simulation 5). It was indicated that excess subsidy support may not promote yield of forage rice. It was, however, observed in most cases that dairy and forage rice integration systems could not be economically established without subsidies.

Highlights

Rice is a staple food for the Japanese and other Asians and plays an integral role in the socio-economy and culture of Asian countries (Islam et al, 2004)
The nutrient requirement model was constructed based on the Japanese Feeding Standards for dairy cattle (MAFF, 1999) and used to predict metabolizable energy requirements (ME), crude protein (CP), dry matter intake (DMI), calcium (Ca), phosphorus (P) and vitamin A (VA)
Simulation 2 showed that the net profit was lower than that obtained in the control scenario until the forage rice yield was increased to 16,000 kg DM/ha

Summary

Introduction

Rice is a staple food for the Japanese and other Asians and plays an integral role in the socio-economy and culture of Asian countries (Islam et al, 2004). Paddy fields have played many functions, including retaining the groundwater level, controlling air temperature and preventing floods, all of which are critical to making the environment sustainable. As there has been less rice consumption than production during the last decade (except in 1993) (MAFF, 1994), Japan does not need to grow excess rice any more, and about one-third of the paddy fields remain set aside at present, which is a potential loss both economically and environmentally (Islam et al, 2004). In Japan, huge amounts of animal feeds, including forage, have been imported from the USA and other countries during the past few decades, indirectly contributing to the drop of self-sufficiency for feed. 14 % of the TDN requirement of dairy cattle depends upon imported forage, which is higher than for other domestic animal species

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