A comparison of three nutritional models for estimating total metabolisable energy requirements for a ewe, beef breeding cow, lamb, and a calf/yearling in New Zealand’s pasture-only system

IF 1.9 3区农林科学 Q2 AGRICULTURE, DAIRY & ANIMAL SCIENCE

Livestock Science Pub Date : 2025-06-27 DOI:10.1016/j.livsci.2025.105766

Joseph A. Adjabui, Patrick H.C. Morel, Stephen T. Morris, Paul R. Kenyon, Peter R. Tozer

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Abstract

In New Zealand (NZ), the metabolisable energy requirements (MER) of ruminants can be estimated using nutritional models from Nicol and Brookes (2017), CSIRO (2007), and NZ’s Agricultural Inventory Model (AIM) of the Ministry for Primary Industries [MPI] (2022). The aim in this study was to calculate the total MER of a ewe, beef breeding cow, lamb, and a calf/yearling in a pasture-only system in NZ under the same assumptions to assess the extent and reasons for variations among the three commonly used nutritional models, and the implications for a given farm/s. The study utilised MER models from the three sources above using a factorial method. This method determines the MER for each physiological phase of an animal, to estimate total MER for each animal. The AIM (MPI 2022) model relative to Nicol and Brookes (2017), and CSIRO (2007) models respectively, estimated 13.4 % and 8.0 % higher MER for a ewe, 16.3 % and 16.6 % for a cow, 1.1 % and 2.0 % lower for a lamb, and 9.2 % and 9.2 % higher for a calf/yearling mainly due to a higher maintenance MER compared to the other models. This has implications for feed budgeting and stocking rates (SR) for a given farm, as the AIM (MPI 2022) model leads to a lower SR than the other two models for a given level of feed available. Energy balances and productivity could be negatively impacted if a model underestimates MER. This also yields different greenhouse gas (GHG) profiles, especially enteric methane, for a given farm and could potentially have financial consequences for farmers if an Emissions Trading Scheme was introduced. For consistency in ME estimates and GHG reporting, further research (feeding trials) is required to compare these model estimates to actual requirements of ruminants under NZ conditions. This could help identify the model that most accurately reflects MER for ruminants in the country.

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在新西兰的牧场系统中，用于估计母羊、肉牛、羔羊和小牛/一岁幼畜总代谢能需求的三种营养模型的比较

在新西兰（NZ），反刍动物的代谢能需要量（MER）可以使用Nicol和Brookes（2017）、CSIRO（2007）和新西兰第一产业部[MPI]的农业库存模型（AIM）（2022）的营养模型来估计。本研究的目的是在相同的假设下，计算新西兰牧场系统中母羊、肉牛、羔羊和小牛/一岁的总MER，以评估三种常用营养模型之间差异的程度和原因，以及对给定农场的影响。该研究利用了上述三个来源的MER模型，使用了析因方法。该方法通过测定动物各生理阶段的MER，来估计每只动物的总MER。与Nicol和Brookes（2017）和CSIRO（2007）模型相比，AIM （MPI 2022）模型估计母羊的MER分别高出13.4%和8.0%，奶牛的MER分别高出16.3%和16.6%，羔羊的MER分别高出1.1%和2.0%，小牛/幼畜的MER分别高出9.2%和9.2%，这主要是由于与其他模型相比，维持性MER更高。这对特定农场的饲料预算和放养率（SR）有影响，因为在给定饲料水平下，AIM （MPI 2022）模型得出的SR低于其他两种模型。如果模型低估了MER，能量平衡和生产力可能会受到负面影响。这也会对特定农场产生不同的温室气体（GHG），特别是肠道甲烷，如果引入排放交易计划，可能会对农民产生潜在的经济后果。为了保持代谢能估计和温室气体报告的一致性，需要进一步的研究（饲养试验）将这些模型估计与新西兰条件下反刍动物的实际需求进行比较。这可能有助于确定最准确反映该国反刍动物的MER的模型。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Livestock Science 农林科学-奶制品与动物科学

CiteScore

4.30

自引率

5.60%

发文量

237

审稿时长

3 months

期刊介绍： Livestock Science promotes the sound development of the livestock sector by publishing original, peer-reviewed research and review articles covering all aspects of this broad field. The journal welcomes submissions on the avant-garde areas of animal genetics, breeding, growth, reproduction, nutrition, physiology, and behaviour in addition to genetic resources, welfare, ethics, health, management and production systems. The high-quality content of this journal reflects the truly international nature of this broad area of research.