A Survey of the Relationship between Climatic Heat Stress Indices and Fundamental Milk Components Considering Uncertainty

Mohammad Milani,Elham Rahmani,Angelika Ploeger,Andreas Hense

doi:10.3390/cli3040876

Abstract

The main purpose of this study is to assess the relationship between four bioclimatic indices for cattle (environmental stress, heat load, modified heat load, and respiratory rate predictor indices) and three main milk components (fat, protein, and milk yield) considering uncertainty. The climate parameters used to calculate the climate indices were taken from the NASA-Modern Era Retrospective-Analysis for Research and Applications (NASA-MERRA) reanalysis from 2002 to 2010. Cow milk data were considered for the same period from April to September when the cows use the natural pasture. The study is based on a linear regression analysis using correlations as a summarizing diagnostic. Bootstrapping is used to represent uncertainty information in the confidence intervals. The main results identify an interesting relationship between the milk compounds and climate indices under all climate conditions. During spring, there are reasonably high correlations between the fat and protein concentrations vs. the climate indices, whereas there are insignificant dependencies between the milk yield and climate indices. During summer, the correlation between the fat and protein concentrations with the climate indices decreased in comparison with the spring results, whereas the correlation for the milk yield increased. This methodology is suggested for studies investigating the impacts of climate variability/change on food and agriculture using short term data considering uncertainty.

Highlights

Climate variability and climate change have direct effects on livestock through stress factors during periods of high temperature as well as indirect effects on their feed and diet [1]
To partially answer the question, we investigated the relationship between physiologically relevant climate indices of cattle (Environmental Stress Index (ESI), Heat Load Index (HLI), modified HLI (HLI New), and Respiratory
A first explanatory analysis of our study focused on the THI and Equivalent Temperature Index (ETI) [5]

Summary

Introduction

Climate variability and climate change have direct effects on livestock through stress factors during periods of high temperature as well as indirect effects on their feed and diet [1]. Investigating the effect of climate variability on livestock and their products is complex. This interaction needs to be investigated using different climatic indices that have considered various climatic parameters. Sharma et al [4] reported that the quality and quantity of milk compounds changed over time due to environmental and climate variability. These authors showed that the milk yield of Holsteins was more sensitive to the climate than the milk yield of Jerseys, whereas the other milk composition of the Jerseys was more sensitive. The milk yield of Holsteins was more sensitive to heat stress compared to Jersey cattle

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