Modeling heat stress under organic dairy farming conditions in warm temperate climates within the Mediterranean basin
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Modeling heat stress under organic dairy farming conditions in warm temperate climates within the Mediterranean basin Isabel Blanco-Penedo 1,2 Alejandro Ruete 4
& Antonio Velarde
1
& Richard P. Kipling
3
&
Received: 25 January 2020 / Accepted: 4 August 2020/ # The Author(s) 2020
Abstract
We studied the effect of heat stress on milk quality in Spanish organic dairy farms using published milk productivity equations. We collected data from 23 weather stations and 14,424 milk test-days for milk yield and milk fat and protein content for the period July 2011 to June 2013. As an indicator of heat stress, we used the maximum daily temperature–humidity index (THI) from 2 days before the milk test date. We fitted the data using hierarchical regression models stratified by farm, cow parity and monthly testday milk records. The effect of THI was deemed low on biological costs through milk yield. However, the known negative relationship between milk yield and milk quality (protein and fat content) became even steeper when the THI increased, suggesting a significant negative correlation between heat stress and milk quality. Therefore, although the milk yield of cows in the organic farming systems analyzed appeared resilient to heat stress conditions, milk quality, a major selling point for organic dairy products, was negatively affected. The model presented here could be used to predict the potential impacts of different climate change scenarios on dairy farming, and to delineate adaptation strategies within organic systems. Keywords Organic farming . Dairy cow . Heat stress . THI . Milk yield . Milk quality . Farm resilience
1 Introduction During the past few decades, there has been a dramatic intensification of animal production in response to the rising global demand for meat and milk. In dairy cattle systems, intensification Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10584-02002818-y) contains supplementary material, which is available to authorized users.
* Isabel Blanco-Penedo [email protected] Extended author information available on the last page of the article
Climatic Change
of production can decrease the thermoregulatory capacity of the animals, and as a result heat stress has become a major challenge facing the dairy sector today (Polsky and von Keyserlingk 2017), with impacts on cattle health, welfare, and productivity (Özkan et al. 2016; Vitali et al. 2015). The issue of heat stress is of particular importance in the context of climate change, which is expected to cause large increases in temperature in regions such as the Mediterranean basin (e.g., Segnalini et al. 2013). Studies in farm animals have shown that across most of this area, animals are at increasing risk of suffering heat stress (Bouraoui et al. 2002; Segnalini et al. 2011) as the frequency and intensity of heat waves continue to rise (Pasqui and Giuseppe 2019). These changes are reflected in an increase across Europe in the number of days when the temperature–humidity index (
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