Ekine-Dzivenu, Chinyere C.

Gebreyohanes, Gebregziabher

Mrode, Raphael A.

Ojango, Julie M. K.

Okeyo Mwai, Ally

CGSpace

Better lives through livestockHeat stress research and adaptation in AfricaC.C. Ekine-Dzivenu, R. Mrode, G.Gebreyohanes, J.M. Ojango, A.M. OkeyoGlobal Farm Platform Write shopChicago -- IllinoisPlatteville – Wisconsin, USA20-24 February 20232One CGIAR: a global research partnership for a food secure future.15 research centres; over 70 countries3ILRI is co-hosted by both the governments of Ethiopia and Kenya, with offices in 8 other countries in Africa (Burkina Faso, Burundi, Mali, Nigeria, Senegal, Tanzania, Uganda and Zimbabwe); 4 countries in Asia (China, India, Nepal and Vietnam).ILRI has approximately 600 permanent staff (with a gender breakdown of 40% female and 60% male).ILRI offices and staff worldwideILRI’s mission is to improve food and nutritional security and to reduce poverty in developing countries through research for efficient, safe and sustainable use of livestock — ensuring better lives through livestock4Demand for food will keep growingProjections based on IMPACT model, Dolapo Enahoro (ILRI), Percentage changes in demand 2010 to 2030• Demand for milk, meat, eggs is increasing fastest in LMICs driven by population, rising incomes and urbanization • Not based on significant over-consumption in LMICs 0.0040.0080.00120.00160.00200.00Beef0.0040.0080.00120.00160.00200.00Poultry0.0040.0080.00120.00160.00200.00MilkEspecially in LMICsShare of total livestock-derived foods produced by small farms in 2010Farms of less than 20 hectares provide:Nearly 50% of the world’s livestock and cereals, and close to 70% of the livestock and cereals in emerging and developing economiesSmallholder farmers currently provide most of the meat, milk and eggs AND staple cereals in LMICs• 1.7 billion people derive some livelihood from livestock; over half a billion depend on livestock• Livestock are fundamental to many economies; provide income, jobs, and supporting risk mitigation• Livestock are the basis for farm sustainability, make food crop farming even possible for many in the Global South –circular bioeconomy,  integrated livestock-food farms5Climate change is expected to have major impacts on livestock productivityClimate change is expected to have major impacts on livestock, including increased heat stress in animals in many parts of the world.Smallholder systems of lower- and middle-income economies are morevulnerable to the impacts of a changing global climate than other dairy systemsEven though dairy cattle in sub-Saharan Africa is subject to high ambient temperature and relative humidity, research on the effect of heat stress on livestock productivity and milk production under this climatic conditions is very limited or largely non-existent.Heat stress is important for dairy production because of its negative effects on productivity and ultimate profitability of the farmers6……cont’dIn cows• Changes in milk composition• Increased occurrence of mastitis • Lengthened oestrus cycle and shortened oestrus periods• Reduced conception rate • Placental malfunction • Decreased foetal growth rate• Increased embryo mortalityIn bulls• Lowered libido• Reduced sperm cell concentration• Reduced sperm cell mobility • Increased % of abnormal sperm cellIn calves• Low birth weight • Reduced growth rate• Reduced ability to survive • Dairy cattle develops numerous physiological mechanisms for copingwith heat stress including reducing feed intake which results in reducedmilk yield.Heat stressThe objective of this study was to detect heat stress thresholds, milk yield loss and individual animal variations using random regression models for dairy cattle from test-day milk records.in KenyaConsidering a one day lag, the estimated heat stress thresholds were about 22°C and 69 index units for TA and THI, respectively.Few published articles quantifying the effect of heatstress on livestock productivity in SSA8The objective of this study was to detect heat stress thresholds, milk yield loss and individual animal variations using random regression models for dairy cattle from test-day milk records in KenyaCommercial farms, 4 main dairy breeds: Friesian, Ayrshire, Jersey and Guernsey As expected, milk loss increased with increasing heat load. The comfort zone for TA was below 22 oC after which a declining trend was observed.  Average milk yield loss was −0.27, −0.19 and −0.35 kg/oC per day for the first, second and third lactation, respectively.The THI comfort zone was below about 69, above which there was a declining trend in milk yield. The average milk yield loss was −0.29, −0.19 and −0.37 kg/THI unit per day for the first, second and third lactation, respectively.The general pattern is a seasonal fluctuation of milk yield following weather variation, particularly temperature. The lowest milk yield was in March which also had the highest average daily temperatures of 20oCHeat stress thresholds were about 22 oC and 69 index units for TA and THI, after which a declining trend was observedThe trends of daily test-day milk yield response to THI for the first three lactationsThere is different degrees of variation btw cows with almost no change in variance along the THI trajectory for cows in the 1st and 3rd lactation but tended to increase across the THI trajectory in the 2nd lactation.Fig 1.Fig 2.Fig 3.This study evaluates the effect of heat stress on milk production and describes the pattern of response of milk yield to increasing heat load, using temperature-humidity index (THI) on test-day milk records of crossbred dairy cows in small holder dairy cattle herds in the sub-Saharan African climate of Tanzania. Part of a wider project called AADGG ( African Asian Dairy Genetic Gains project) which is developing and testing a multi-country genetic gains platform using smallholder dairy cattle  performance data and genomic informationDaily milk yield followed the pattern of a lactation curve and peaked at 8.5l in 60 daysSeasonal fluctuation of milk yield following weather variationResults indicate that cows experienced heat stress between THI values of 67 and 76 and daily milk production, reduced by 4.16% to 14.42% across THI groups (heat stress levels).Milk yield showed a W-shaped pattern of response across the THI scale at the population level, indicating a non-linear relationship between milk yield and THITHI and its squared term were significantly negatively and positively  (-0.61, 0.004) associated with milk production indicating that there is no unique slope and change in milk yield is different across  the THI interval.Fig. 1.Fig.2.Fig. 3.10ObjectiveThe goal of this study, was to evaluate changes in genetic parameters for milk yield and heat tolerance in small holder dairy cattle population of Tanzania under different heat stress (THI) thresholds as a first step toward including this trait in selection indices for dairy cattle in the region.11ResultsMean Std RangeMilk, liters 7.90 4.21 1 - 38Temp, oC 21.05 5.50 11.6 - 30.64RH, % 80.48 3.73 68.06 - 89.61.THI 76.3 3.78 69 - 82THI thresholdsVariance Components 69 71 78σ2a 9.83(1.21) 9.16 (1.32) 7.52(1.39)σ2aht 0.10(0.61) 1.96(1.20) 2.15(0.95)σa (a, aht) -1.00(0.59) -2.10(0.93) -0.24(0.72)rg(a, aht) -0.99(NE) -0.50(0.15) -0.06(0.19)rpe (pe,peht) -0.92(NE) 0.64(NE) 0.90(NE)σ2wys 8.85(0.38) 6.65(0.37) 5.47(0.43)σ2e 5.47(0.12) 4.79(0.12)    4.15(0.18)h2 0.38 0.44 0.50Table 2. Estimates for genetic parameters and heritability for milkproduction at different THI thresholds (heat stress levels).-10123469 70 71 72 73 74 76 77 78 79 80 81 82EBVTHIEstimated breeding value (EBV) for a random sample of sires 65769 55133 59078 63039 51938 59188 59155Table 1. Basic description of milk yield and weather data.Objective:  Evaluate changes in genetic parameters for milk yield and estimate breeding values for milk production under heat stress conditions.Data –phenotype, genotype, weatherVariance ComponentsTHI Thresholds69 71 78σ2a 9.83 9.16 7.52σ2aht 0.10 1.96 2.15σa (a, aht) -1.00 -2.10 -0.24rg(a, aht) -0.99 -0.50 -0.06Use of the data for Genomic analysis of milk yield and heat tolerance for small holder dairy system of sub-Saharan AfricaPhenotypeMonthly milk collected, between Nov 2016  and May 2020GenotypeCows and bulls genotyped on the 50K chip and imputed to the Illumina HD chipClimate DataObtained using GPS coordinates of the farms, data includes daily maximum and minimum relative humidity.-10123469 70 71 72 73 74 76 77 78 79 80 81 82Milk EBV  THI65769 55133 59078 63039 51938 59188 59155Results   Antagonistic relationships between milk yield and thermal tolerance. Milk production reduced by 4.16% to 14.42% across THI groups (heat stress levels).Reaction norm shows genetic variations exist between sires, indicating the possibility to select animals that perform optimally in different environments.Chinyere Ekine-Dzivenucekine@cgiar.org13Take home message• Our study detected antagonistic relationships between milk yield and thermal tolerance for heat stress.• This result suggests that selection for increased milk yield disregarding heat tolerance will result indeteriorating heat tolerance in this population.• It is important to note that not observing animals across the THI gradient due to low retention of cows in thesmall holder farms may contribute to the low permanent environmental variances observed.• Moderate heritability estimates for milk yield over different heat stress levels show potential to geneticallyimprove milk yield for climate conditions with high THI values howbeit with care to avoid unfavourablecorrelated response of thermal stress on milk production.• The reaction norms for the sire EBVs along the trajectory of THI indicates that genetic variations exist which can be used to select animals that perform optimally in different environments.14Take home message cont’dIn the longer term• Identifying sires and dams that carry genes to improve thermotolerance and using them for breedingIn the short termPrecautionary measures need to be taken for mitigation• Herd management and animal husbandry measures to protect the animal from too much heat. - Direct protection from sunlight using shades in form of trees- Corrugated sheet metal painted white on the top • Provision of adequate feed and water at all times• Increasing the use of concentrate when the weather is hot15Addressing the challengesfacing small holder livestock (dairy) systems through innovative application of ICT and genomic technologyAfrican Asian Genetic Gain Program Little or no systematic way for data collection to drive  sustainable breeding programs. Continuous Phenotyping  across a wide range of very dispersed smallholder farms16Acknowledging our numerous partnersDairy Farmers & Farmer organizationsNational/regional Institutions/govts.THANK YOUThis presentation is licensed for use under the Creative Commons Attribution 4.0 International Licence.better lives through livestockilri.orgILRI thanks all donors and organizations who globally supported its work through their contributions to the CGIAR system

Heat stress research and adaptation in Africa

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Heat stress research and adaptation in Africa

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