Impact of Heatwaves on the Physiology and Retail Meat Quality of Lambs.

Minghao Zhang,Pragna Prathap,Surinder S Chauhan,Aleena Joy,Robyn D Warner,Ting Ma,Archana Abhijith,Frank R Dunshea,Kristy Digiacomo

doi:10.3390/foods11030414

Minghao Zhang, Pragna Prathap + Show 7 more

Open Access

https://doi.org/10.3390/foods11030414

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Abstract

The experiment investigated the impact of heatwaves (HWs) on the physiology, postmortem muscle metabolism and meat quality of lambs. Seventy-two second-cross lambs (Poll Dorset × (Border Leicester × Merino)) were selected and exposed to either 1, 3 or 5 days of HWs or thermoneutal (TN) (28–38 °C and 40–60% relative humidity, RH; 18–21 °C, 40–55% RH) conditions in climate-controlled chambers. Lambs exposed to 1–5 days of a HW exhibited higher respiration rates (RRs), rectal temperatures (RTs), skin temperatures (STs) and heart rates (HRs) compared to lambs exposed to an equal duration of TN conditions. However, HWs had no significant effects on muscle metabolism (rate and extent of pH decline, muscle glycogen and lactate content) and meat quality (cooking loss and shear force). Similarly, there were limited impacts of 1–5 days of HW on the colour (L*, a*, b* and R630/580) and drip loss of the longissimus thoracis et lumborum (LTL) and semimembranosus (SM) muscles for 4 days’ overwrap retail display. Results suggest that short-duration HWs (1–5 days) had significant negative effects on animal physiology but had no effect on the muscle metabolism and meat quality.

Highlights

Heat stress (HS) is one of the biggest challenges facing animal production over the summer months and is likely to be accentuated by climate change and global warming
Temperature–humidity index (THI), which is calculated based on the ambient temperature and the relative humidity, is commonly used to measure heat stress
The average temperature-humidity index (THI) in the simulated HW room was 30.1 in the daytime and 23.9 at night, indicating that the lambs were exposed to high-temperature conditions during the day and were not able to offload heat overnight (Figure 1)

Summary

Introduction

Heat stress (HS) is one of the biggest challenges facing animal production over the summer months and is likely to be accentuated by climate change and global warming. High ambient temperature and humidity compromise animal production and welfare as animals cannot maintain core body temperature due to the extra heat load [1]. Research over the last decade has suggested that meat quality problems, such as dark-cutting (high ultimate pH) or pale soft exudative (PSE, rapid pH fall post-mortem) meat, are more prevalent in summer [2,3,4]. A higher incidence of dark-cutting meat has been reported in small ruminants such as sheep and goats when the heat exposure period is longer than 1 month, resulting in lower feed intake and decreased body weight gain [2,5,6]. The effects of short-duration heat events, such as those experienced during a heatwave (HW), on sheep meat quality remain unknown

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