THE POTENTIAL FOR DEVELOPING AN HEAT STRESS EARLY WARNING SYSTEM

FOR LIVESTOCK IN JAMAICA THE THERMAL HEAT INDEX (THI) AS A RESPONSE TO CLIMATE CHANGE

1Cicero H. O. Lallo and 2Dale Rankine1Open Tropical Forage and Animal-Production Laboratory,

Department of Food ProductionFaculty of Food and Agriculture The University of the West Indies, St. Augustine (campus) Trinidad and Tobago West

Indies. 2 CEADIR Jamaica, The University of the West Indies Mona

(Campus) Jamaica West Indies

 

INTRODUCTION

• The islands of the Caribbean are particularly vulnerable with respect to the impacts of climate variability and change.

• Generally, temperatures remain fairly constant with highest values occurring in June-August, and presents a major challenge for livestock and livestock farmers, since there is often need for cooling to prevent adverse impacts on inter alia their production, reproductive performance and thermoregulation.

• Climate change will only exacerbate these challenges in the Caribbean, especially with respect to increasing temperatures. Both the IPCC and Caribbean Studies have reported that the expected range of increase is 0.7 to 1.8 0C by 2050 and 1.1 to 3.2 0C by 2090 for Jamaica’s mean annual temperature

INTRODUCTION

•   The frequency of very hot days and nights, will continue to increase reaching 30-98% of days annually by 2090. The trend is set to continue and likely exacerbated by climate change. 

• Animal management systems and practices would need to be changed.

•  E.g. early warning system can involve the Meteorology Service and the Media, to warn livestock farmers of impending heat stress conditions. 

Effect of climate on Animal Production

• It is reported that Jamaica receive on an average 1825 kwH/m2 per year of direct solar radiation and peaks around June. 

• Jamaica is also experiencing a warming trend with regards to ambient temperature

• This will have the potential to create heat stress conditions.

Indices used for livestock:• Chicken:• THIbroilers =0.85Tdb +0.15Twb Tao and Xin (2003)• THIlayer = 0.6Tdb + 0.4 Twb Zulovich and De Shazer

(1990)

• Ruminants:• THI = (1.8 xTdb + 32) – ([0.55-0.0055 x RH] x (1.8 x Tdb-26.8)) NRC (1971)

THI = (1.8 x Tdb + 32) – ((0.55 – 0.0055 x RH) x (1.8 x Tdb – 26) Hahn et al. (2003)

• Rabbit:• THI =T db

0 C- [(0.31- 0.31 RH) (Tdb 0C -14.4)] Maria et al (2001)

• Pigs:• THI= Tdb –[0.55-(0.0055x RH)] x (Tdb-14.5) Zumbach et al. (2008)

.  The thermal environment created challenge the animal’s thermoregulatory mechanisms.

• The direct effect of climate on feed intake, growth rate and reproductive performance are due largely to heat stress

• Heat stress also suppresses the immune system and increases animal susceptibility to various diseases

•  Haematological parameters such as the amount of red blood cells, haemoglobin, erythrocytes and packed cell volume are also affected by heat stress

Thermo-regulatory function traits include respiration rate, heart rate and rectal temperature are easily measure and can serve as

an indicator of heat stress

Threshold THI RR (br/min)

Normal <74.0 <90

Alert >74 - <79 90-110

Danger >79 <84 110-130

Emergency >84 >130

The differences in thermal challenges (THI ) show patterns due to season and is normally reflected in animal performance

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Rabbits housed in open sided house

•  Temperature humidity index of 25- 28 reflected no heat stress while 28- 29, 29- 30 and above 30 reflected moderate, severe and very severe heat stress, respectively.  The temperature humidity index in the both the dry and wet season may be high due to the high temperature and humidity.  High temperature and humidity reduces the ability of rabbits to dissipate heat through panting due to the fact that the air is saturated thus crippling the process of heat loss through evaporation

Physiological State Rectal Temperature Respiration Rate

Doe:

Lactating 38.09 (±0.24)a 103.1 (± 4.00)a

Gestating 38.92 (± 0.21)a 108.1 (± 3.50)a

Open 38.99 (± 0.20)b 108.2 (± 3.29)a

Bucks 39.04 (± 0.33)bc 97.7 (± 5.54)a

The effect of year and season on litter size at birth and at weaning, litter weight at birth, total born alive and mortality of rabbits reared intensively at the University Field Station, 

Trinidad. Pre-wean performance

Year Litter size Litter weight Total born alive Litter size at weaning Mortality

2005 5.96(±0.16)a 304.9(±8.45)a 5.84(±0.17)a 4.28(±0.19)a 28.7(±2.94)a

2007 6.62(±0.18)a 328.4(±9.22)a 6.48(±0.18)a 4.66(±0.21)a 31.44(±3.21)a

2010 5.47(±0.25)a 270(±12.90)a 5.45(±0.26)a 4.37(±0.29)a 20.49(±4.49)a

Season

dry 6.05(±0.15)a 309.2(±7.76)a 5.96(±0.15)a 4.25(±0.17)a 31.11(±2.70)a

Wet 6.16(±0.11)a 313.3(±5.80)a 5.80(±0.11)a 4.22(±0.13)a 29.97(±2.02)a

Respiration Rate (br /min) Rectal Temperature ( °C)

Breed Type AM Mean (± SEM)

PM Mean (± SEM)

AM Mean (± SEM)

PM Mean(± SEM)

BB 39.22 (±1.44) 110.5 (±2.78) 38.38 (± 0.11) 39.14 (± 0.10)

WA 38.43 (±1.41) 116.2 (±4.63) 38.41 (± 0.08) 39.45 (± 0.10)

Prob. p>0.05 p>0.05 p>0.05 P<0.001

The relationship between grazing time and temperature and relative humidity and THI were explored for hair sheep.  When the parameters were examined for non-pregnant female at pasture, 

the following significant (P< 0.001) regression was obtained:

•LnYp = 0.281 X1 – 0.00445 X12 – 3.60 X2 (n = 236; R2 = 0.70)

•LnYp = 0.0254 X3 (n = 236; R2 = 0.62).

•Where: Yp = grazing time of sheep offered pasture (mins.), X1 =

temperature (C) X2 = relative humidity (%)and X3 = THI.

Towards Developing an Early Warning THI system for livestock

• The question to be asked is how do we adapt our livestock production system to meet the thermal challenges of our current and future climates?. We therefore need to adopt risk management strategy by first considering perceived thermal challenge, and then the potential consequences and respond accordingly to reduce the impact of such challenges.

• Mitigating actions would include; provision of shade, modification of the environment by housing, sprinkling, or active cooling.

• The Livestock Weather Safety Index (LWSI) a THI base LWSI was develop in the USA and was considered as a valuable tool for producers.

• Heat waves (extreme events expected) are generally short-term high temperature weather patterns that generally find livestock producers unprepared and can have grave economic consequences.• There is an urgent need to develop a warning

system and to educate CARICOM farmers in the region to be climate smart and to adopt mitigation strategies to enhance food security the following is therefore suggested to move forward:

• 1. Characterize and develop a THI zone map for the region based on THI similar to rainfall pattern map created by meteorological bodies.

• 2. In conjunction with the meteorological services and network news develop a system for forecasting THI as a feature of the weather news in an effort to develop an early warning forecast for farmers.

• 3. Develop educational programs to run workshops to educate and train extension officers ( train the trainers workshops) and farmers what THI numbers mean and what actions can be taken to attenuate the effect and reduce heat stress on the animals. This should also include nutrition and the management of animals at pasture.

• 4. Develop training program to have farmers adopt methods of forage conservation and how to meet the nutritional needs of their animals in a changing climate.

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