Progress 02/01/17 to 01/31/22
Outputs
Target Audience:Researchers in beef cattle and genetics/genomics field, beef cattle producers, stakeholders. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This grant has helped train two PhD students, two Masters student, and four undergraduate students. How have the results been disseminated to communities of interest?The PI of the grant, Raluca Mateescu, gave many international and national presentations on the importance of developing genomic tools for thermotolerance in beef cattle. A particular project overview received national and international interest and generated inteviews with many media sources. Beef producers and industry stakeholders have also been targeted with online and in-print publications and presenattions during field days and Association Meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact A unique resource population was created through this grant, a population of 2,273 heifers with detailed thermotolerance phenotypes and high-density 250K functional genotypes. Brahman cattle had a significantly superior resilience to heat stress, but when exposed to severe heat stress even Brahman cattle could not adequately cope. Along with the number of hours under high heat stress THI during the day, the opportunity to cool down during the night seems to be the critical factor. These facts provide strong evidence that development of knowledge and tools needed to implement a genetic program to improve heat tolerance is critically and urgently needed. Climate change predictions with heat stress conditions intensifying and expanding into currently temperate zones indicate the imperative need to develop effective strategies to ensure sustainable beef production systems. Climate change predictions with heat stress conditions intensifying and expanding into currently temperate zones indicate the imperative need to develop effective strategies to ensure sustainable beef production systems. Effective strategies will require the identification of the genes conferring the superior thermotolerance in Brahman cattle. This will allow genomic selection within breeds for superior productivity under hot and humid conditions or introduction of thermotolerance variants in thermo-sensitive breeds through targeted introgression or gene editing technology. Data collected. A total of 2,273 heifers were recorded for detailed thermotolerance phenotypes and have high-density 250K functional genotypes. Phenotypes include: 15 min interval vaginal temperature over 3 continuous days during summer, coat score, hair length and diameter, sweating rate, chute and exit temperament, body condition score, skin biopsies and skin histology measures (sweat gland area, dermis and epidermis thickness, sweat glad depth), weights. Fertility data were collected from subsequent controlled breeding. Breeding seasons began with estrous synchronization and AI based on estrous detection for one AI service, and then exposure to natural service mating. Summary statistics and discussion of results Estimates of heritability for hair diameter, undercoat length, topcoat length, body temperature under low THI conditions and body temperature under high THI conditions were 0.50, 0.67, 0.42, 0.32, and 0.26, respectively. As Brahman breed composition increased by 25% undercoat length, topcoat length, body temperature under low THI conditions and body temperature under high THI conditions decreased by 1.32 mm, 2.94 mm, 0.11°C and 0.14°C, respectively. Under both low and high THI conditions cattle with 25% Brahman breed composition or greater maintained a significantly lower body temperature than the 100% Angus breed group. The reaction norm model estimated an intercept and slope measuring the change in body temperature per unit increase in THI environmental heat stress for different breed groups of animals and allows the identification of genotypes which are robust, with low slope values indicative of animals that are able to maintain normal body temperature across a range of environments. The repeated measures mixed model showed that Brahman cattle have an advantage under moderate or high heat stress conditions but both Angus and Brahman breed groups are greatly affected when heat stress is severe. A critical factor appears to be the opportunity to cool down during the night hours more than the number of hours with extreme THI. A GWAS was performed for all thermotolerance related traits measured on the resource population. Records of body temperature under high (84-86), average (79-81), and low THI (74-76), difference in vaginal temperature between high and low THI, PC1, PC2, and aggregate measures RNintercept, RNslope and EBLUP were available on 2,273 heifers. The proportion of phenotypic variance explained by SNP genotypes (was low to medium-high for the three aggregate measures describing the thermotolerance varying from 0.07 for EBLUP to 0.20 for RN slope and 0.22 for RN Intercept, indicating a good predictive power for all these traits. The major objective of the on-going project is to identify genomic regions controlling thermotolerance and preliminary analyses identified several significant genomic regions for each trait. The estimated genomic heritability for undercoat length in this population was 0.30 with a standard error of 0.05. We identified eight SNP significantly associated with undercoat length within a 300kb region on BTA 12. This region contains the gene PCCA. Seven of the significant SNP were located within PCCA and one of the significant SNP was an upstream variant (rs133787763). Of the seven intragenic SNP there were two missense mutations (rs133791585, rs210751638), four intron variants (rs383191895, rs110703144, rs134127983, rs210217784) and one splice region variant (rs41679981). Key outcomes The genetic parameters estimated in this study indicate that hair characteristics are highly heritable and core body temperature under various THI conditions is moderately heritable. These values of heritability indicate a large, exploitable genetic variance in body hair length and core body temperature which can be selected upon to improve heat tolerance in cattle. As Brahman breed influence increased both hair length and body temperature decreased, indicating that cattle producers can improve thermotolerance by incorporating Brahman germplasm into their herds. The genetic variants identified for both undercoat and topcoat are of great biological relevance. The variants have the potential to be used for selection in order to breed for animals with shorter hair, leading to greater thermotolerance and potentially increasing production in hot, humid climates. The current study is limited to the potential functional variants available on the GGP F250 array and should be followed up with whole genome sequence data to refine putative functional mutations. The beneficial effect of Brahman genetics is dependent on the magnitude of environmental heat stress. When breed groups were exposed to moderate or high heat stress, the Brahman group had a significantly superior resilience to heat stress, but when exposed to severe heat stress even Brahman group could not adequately cope. Along with the number of hours under high heat stress THI during the day, the opportunity to cool down during the night seems to be the critical factor. Climate change predictions with heat stress conditions intensifying and expanding into currently temperate zones indicate the imperative need to develop effective strategies to ensure sustainable beef production systems. Effective strategies will require the identification of the genes conferring the superior thermotolerance in Brahman cattle. This will allow genomic selection within breeds for superior productivity under hot and humid conditions or introduction of thermotolerance variants in thermo-sensitive breeds through targeted introgression or gene editing technology.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Dikmen S., K.M. Sarlo Davila, E. Rodriguez, T.L. Scheffler, P.A. Oltenacu and R.G. Mateescu. 2020. Comparison of Tympanic and Tail Temperatures in Angus and Brahman Steers. J Anim Sci Res 4(4). dx.doi.org/10.16966/2576-6457.147
Sarlo Davila K.M., A. Howell, A. Nunez, A. Orelien, V. Roe, E. Rodriguez, S. Dikmen, and R.G. Mateescu. 2020. Genome-wide association study identifies variants associated with hair length in Brangus cattle. Animal Genetics. 51:811-814. doi: 10.1111/age.12970
Mateescu R.G., K.M. Sarlo Davila, S. Dikmen, E. Rodriguez, and P.A. Oltenacu. 2020. The effect of Brahman genes on body temperature plasticity of heifers on pasture under heat stress. J. Anim. Sci. 1:98(5):skaa126. DOI: 10.1093/jas/skaa126
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Sarlo Davila K., Howell A., Nunez A., Orelien A., Roe V. Rodriguez E., Dikmen S. and Mateescu R.G. 40 PRLR and PCCA variants associated with hair length in Brangus heifers. J Anim Sci. 2020. 98 (Suppl. 4):16.
Mateescu R.G., Sarlo Davila K., Dikmen S., Nunez A., Rodriguez E., and Oltenacu P.A. Phenotypic plasticity of heat tolerance in beef cattle. J Anim Sci. 2020. 98 (Suppl. 4):51.
Sarlo Davila K., Howell A., Nunez A., Orelien A., Roe V., Rezende F., Dikmen S. and Mateescu R.G. Genome-wide association study for hair length in Brangus heifers. Plant and Animal Genome Meeting, San Diego, CA. (2020).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Sarlo Davila K.M., Rodr�guez E., Nunez Andrade A.N., Zayas G.A., and Mateescu R.G.. Integration of GWAS, network, and pathway analysis reveals novel insights into thermotolerance in beef cattle. 24th Conference of the Association for the Advancement of Animal Breeding and Genetics. Virtual Meeting (2021).
Mateescu R.G., Rezende F.M., Sarlo Davila K.M., Dikmen S., Nunez Andrade A.N., Hernandez A., and M.A. Elzo. Revealing phenotypic and genetic relationships underlying the thermotolerance-production complex in beef cattle. 24th Conference of the Association for the Advancement of Animal Breeding and Genetics. Virtual Meeting (2021).
- Type:
Other
Status:
Submitted
Year Published:
2020
Citation:
Impact of Brahman genetics on body temperature of heifers under heat stress. R.G. Mateescu. Frontline Beef Producer. Fall 2020, Vol. 12, Issue. 2, pg. 61-62.
Sweating as a heat exchange mechanism in beef cattle. R.G. Mateescu, Kaitlyn Sarlo Davila and Serdal Dikmen. The Florida Cattleman & Livestock Journal. Sept 2020, Vol. 84, No. 12, pg. 43-44.
Cool genes for hot climate. Progressive Farmer. September 2020.
Comparison of tympanic and tail temperatures in Angus and Brahman steers. Kaitlyn Sarlo Davila, Serdal Dikmen, Eduardo Rodriguez, Tracy Scheffler, Pascal Oltenacu and R.G. Mateescu. The Florida Cattleman & Livestock Journal. August 2020, Vol. 84, No. 11, pg. 50-51.
The effect of Brahman genes on body temperature of heifers on pasture under heat stress. Kaitlyn Sarlo Davila, Serdal Dikmen, and R.G. Mateescu. The Florida Cattleman & Livestock Journal. July 2020, Vol. 84, No. 10, pg. 84-85.
|
Progress 02/01/20 to 01/31/21
Outputs
Target Audience:Researchers in beef cattle and genetics/genomics field, beef cattle producers, stakeholders Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This grant has helped train two PhD students, two Masters student, and four undergraduate students How have the results been disseminated to communities of interest?The PI of the grant, Raluca Mateescu, gave many international and national presentations on the importance of developing genomic tools for thermotolerance in beef cattle. A particular project overview received national and international interest and generated inteviews with many media sources. Beef producers and industry stakeholders have also been targeted with online and in-print publications and presenattions during field days and Association Meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Data Collected Vaginal temperature was recorded every 15 minutes for 3 consecutive days during summer with an iButton temperature measuring device. Coat score, sweating rate, chute score, exit score, and weight were recorded as the animals passed through the chute. At the same time, two skin biopsies were taken from each animal, one for skin histology measurements and one was saved in liquid nitrogen for subsequent transcriptomic analyses. Environmental measurements of dry bulb temperature and relative humidity were collected every 15 min during the entire time of data collection to calculate the temperature-humidity index (THI) to describe the environment. Only data recorded during three 24-hour periods starting at 2400 h on the day of iButton insertion were used in subsequent analyses to reflect vaginal temperature of cows maintained on pasture without any human interaction. All 2,273 Brangus heifers and more than 600 multibreed heifers (from 100% Angus to 100% Brahman) from the UF multibreed population have the same battery of phenotypic traits recorded. All animals in both populations have been genotyped with the GGP Bovine F250K SNP chip. Key Outcomes Differences in body temperature between Angus and Brahman animals are evident during days of low or average THI-load, with Brahman cattle being able to maintain a lower body temperature throughout these days and Angus cattle having body temperatures above 39?C for extended periods of the day. However, during a high heat stress day, even Brahman cattle experience an increase in body temperature indicating that the Brahman breed are affected when heat stress is severe. All other breed groups with proportion of Brahman genes varying from 25% to 75% were in between Brahman and Angus curves. All animals in our training populations have been genotyped with the GGP Bovine F250K SNP chip which consists of mostly functional SNPs. GWAS was performed on sweat gland area in the UF multibreed population. The GWAS was performed using the single-locus mixed linear model procedure implemented in Golden Helix SVS v8.4.4 software (Golden Helix Inc., Bozeman, USA). The efficient mixed model association (EMMAX) approach in combination with a genomic relationship matrix was used to directly estimate the genetic and residual variance components σ2g and σ2e and the proportion of variance explained by the effects of significant SNPs. Contemporary groups were defined based on year and age of the heifers and were fit as fixed class effects in genomic analyses. Several highly significant regions were identified associated with sweat gland size. Among the annotated genes identified in these regions, several have obvious involvement in skin development, morphogenesis of epidermis, hair follicles, and sweat ducts
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Sarlo Davila K.M., Rodr�guez E., Nunez Andrade A.N., Zayas G.A., and Mateescu R.G.. Integration of GWAS, network, and pathway analysis reveals novel insights into thermotolerance in beef cattle. 24th Conference of the Association for the Advancement of Animal Breeding and Genetics. Virtual Meeting (2021).
Mateescu R.G., Rezende F.M., Sarlo Davila K.M., Dikmen S., Nunez Andrade A.N., Hernandez A., and M.A. Elzo. Revealing phenotypic and genetic relationships underlying the thermotolerance-production complex in beef cattle. 24th Conference of the Association for the Advancement of Animal Breeding and Genetics. Virtual Meeting (2021).
|
Progress 02/01/19 to 01/31/20
Outputs
Target Audience:Researchers in beef cattle and genetics/genomics field, beef cattle producers, stakeholders. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This grant has helped train one PhD students, one Masters student, and four undergraduate students. How have the results been disseminated to communities of interest?The PI of the grant, Raluca Mateescu, gave 4 international and national presentations on the importance of developing genomic tools for thermotolerance in beef cattle. A particular project overview received national and international interest and generated inteviews with many media sources. Beef producers and industry stakeholders have also been targeted with online and in-print publications and presenattions during field days and Association Meetings. What do you plan to do during the next reporting period to accomplish the goals?Phenomics for thermal tolerance and genomic data will be integrated to identify chromosomal regions associated with regulation of body temperature. We will estimate the accuracy of genomic prediction and define a sufficient reduced SNP set to be used in a MAS program. Functionally annotated genes will be assigned to markers associated with thermal tolerance to transition from naïve to informed genomic prediction. Functionally-enriched gene networks will be developed to identify major drivers and pathways controlling thermal tolerance.
Impacts
What was accomplished under these goals?
A total of 2,273 heifers were recorded for detailed thermotolerance phenotypes and have high-density 250K functional genotypes. Phenotypes include: 15 min interval vaginal temperature over 3 continuous days during summer, coat score, hair length and diameter, sweating rate, chute and exit temperament, body condition score, skin biopsies and skin histology measures (sweat gland area, dermis and epidermis thickness, sweat glad depth), weights. Fertility data were collected from subsequent controlled breeding. Breeding seasons began with estrous synchronization and AI based on estrous detection for one AI service, and then exposure to natural service mating. The ability to evaluate the change in body temperature of individual animals in response to environmental challenge is critical if thermotolerance is to be included as a potential selection goal in a breeding program. Two strategies were used to accomplish this task. First, body temperatures of individual cows when THI was low (74-76), average (79-81) and high (84-86) were used in a random regression mixed model to estimate the reaction norm parameters for individual animals: an intercept (RNintercept) and a slope (RNslope). The slope of the reaction norm describes individual's change in body temperature in response to an increase of 5 THI units (its phenotypic plasticity) and the intercept describes the vaginal temperature when exposed to low heat stress (THI of 74-76). The pattern of variation in reaction norms across a population is described by the between-individual variances in intercept, the between-individual variation in slope and the covariance between intercept and slope, which can be converted into a correlation coefficient. In our study, the variances for the RNintercept and RNslope were 0.062 and 0.014, respectively, the covariance was -0.007, and the correlation was -0.25. Second, we used hourly body temperature for individual cows in a mixed model with group, day(group) and hour(group*day) as fixed effects and cows(group) as random effect. Repeated measures were used to account for correlation among body temperature measures of individual cows using first order auto-regressive structure. The estimates of random effects adjusted for fixed effects are EBLUP predictors for individual cows and represent another measure to compare cows with respect to their thermotolerance. With this model, between and within individual variances were 0.066 and 0.032 and the estimate for AR(1) parameter was 0.795. Pearson correlations between these traits were -0.25 (RNintercept - RNslope), 0.59 (RNintercept - EBLUP) and 0.023 (RNslope - EBLUP). These measures are complementary and are used in GWAS to identify genomic variants controlling thermotolerance. A GWAS was performed for all thermotolerance related traits measured on the resource population. Records of body temperature under high (84-86), average (79-81), and low THI (74-76), difference in vaginal temperature between high and low THI, PC1, PC2, and aggregate measures RNintercept, RNslope and EBLUP were available on 2,273 heifers. GWAS was performed using the single-locus mixed linear model procedure implemented in Golden Helix SVS v8.4.4 software (Golden Helix Inc., Bozeman, MT, USA). The efficient mixed model association (EMMAX) approach in combination with a genomic relationship matrix was used to directly estimate the genetic and residual variance components σ2g and σ2e and the proportion of variance explained by the effects of significant SNPs (Kang et al., 2010; Segura et al., 2012). Pseudo-heritability was estimated as h2 = σ2a / (σ2e + σ2e) based on the estimates of the variance parameters (Kang et al., 2010). Twelve contemporary groups were defined based on the group each heifer was measured in (12 groups over 3 years) and were fit as fixed class effects in genomic analyses, except for the reaction norm intercept and slope where the records have been already adjusted for the contemporary group. The proportion of phenotypic variance explained by SNP genotypes (was low to medium-high for the three aggregate measures describing the thermotolerance varying from 0.07 for EBLUP to 0.20 for RN slope and 0.22 for RN Intercept, indicating a good predictive power for all these traits. The major objective of the on-going project is to identify genomic regions controlling thermotolerance and preliminary analyses identified several significant genomic regions for each trait.
Publications
- Type:
Book Chapters
Status:
Published
Year Published:
2019
Citation:
? Mateescu R.G. 2019. Chapter 2: Genetics and breeding of beef cattle. In: Animal Agriculture: Sustainability, Challenges and Innovations. Elsevier Science, Edited by Bazer, Lamb & Wu. ISBN-13: 978-0128170526, pg 21-36.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Sarlo Davila K.M., H. Hamblen, P.J. Hansen, S. Dikmen, P.A. Oltenacu and R.G. Mateescu. 2019. Genetic parameters for hair characteristics and core body temperature in a multibreed Brahman-Angus herd. J. Anim. Sci. 97:32463252. doi: 10.1093/jas/skz188
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Sarlo-Davila K.M., A. Howell, A.N. Nunez Andrade, Orelein A., Roe V., Rezende F., Dikmen S., and R.G. Mateescu. (2019). Genetic parameters for hair characteristics and vaginal temperature in a multibreed Brahman-Angus herd under hot humid conditions. Proceedings 5th Annual Research Symposium, UF Animal Sciences Graduate Program, St. Augustine, FL, pg. 39.
Howell A., K.M. Sarlo Davila, Dikmen S., E.E. Rodriguez and R.G. Mateescu. (2019). The Effects of Polymorphisms in Cadherin on Sweat Gland Area in Brangus Heifers. Proceedings 5th Annual Research Symposium, UF Animal Sciences Graduate Program, St. Augustine, FL, pg. 23.
Nunez Andrade A.N., K.M. Sarlo Davila, J.D. Leal Gutierrez, Dikmen S., A. Howell and R.G. Mateescu. (2019). Effect of PIP and IRX1on hair coat characteristics of Brangus heifers. Proceedings 5th Annual Research Symposium, UF Animal Sciences Graduate Program, St. Augustine, FL, pg. 26.
Dikmen S., K.M. Sarlo Davila, E.E. Rodriguez and R.G. Mateescu. The differences in thermoregulation ability and genetic parameters of skin traits in Angus, Brahman and their crossbreds. American Association of Animal Science Annual Meeting. (2019).
Sarlo Davila K.M., F. Rezende, S. Dikmen, F. Pe�agaricano and R.G. Mateescu. Genome-wide association study for hair coat length in Brahman-Angus crossbred heifers. 37th International Society for Animal Genetics Conference (ISAG), Lleida, Spain. (2019).
Mateescu R.G. Meat quality and thermotolerance in Bos Indicus influenced cattle. 68th Annual Florida Beef Cattle Short Course, Gainesville, FL. (2019).
Mateescu R.G., Sarlo Davila K., Hamblen H., Dikmen S., Elzo M.A., Oltenacu P.A., and Hansen P.J. Genetics of heat stress response in cattle. Plant and Animal Genome Meeting, San Diego, CA. (2019).
Mateescu R.G., Sarlo Davila K., Hamblen H., Dikmen S., Elzo M.A., Oltenacu P.A., and Hansen P.J. Reaction norm model of body temperature response to heat stress in beef cattle. Plant and Animal Genome Meeting, San Diego, CA. (2019).
Improving thermotolerance in beef cattle a genomic approach. (Talk, 45m) Beef Improvement Federation Convention, Brookings, SD, May 18-21, 2019.
Genetic tests & genomics of heat tolerance. (Talk, 20 min). Adams Ranch Annual Field Day. Gainesville, FL. Nov 13-14, 2019.
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Progress 02/01/18 to 01/31/19
Outputs
Target Audience:Researchers in beef cattle and genetics/genomics field, beef cattle producers, stakeholders. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This grant has helped train one PhD students, one Masters student, and four undergraduate students. How have the results been disseminated to communities of interest?The PI of the grant, Raluca Mateescu, gave 6 international and national presentations on the improtance of developing genomic tools for thermotolerance in beef cattle. A particular project overview received national and international interest and generated inteviews with many media sources. Beef producers and industry stakeholders have also been targeted with online and in-print publications and presenattions during field days and Association Meetings. What do you plan to do during the next reporting period to accomplish the goals?DNA will be exrcated from blood samples collected from all heifers in the study and will be genotyped with the 250K functional SNP chip. Phenomics for thermal tolerance and genomic data will be integrated to identify chromosomal regions associated with regulation of body temperature. We will estimate the accuracy of genomic prediction and define a sufficient reduced SNP set to be used in a MAS program. Functionally annotated genes will be assigned to markers associated with thermal tolerance to transition from naïve to informed genomic prediction. Functionally-enriched gene networks will be developed to identify major drivers and pathways controlling thermal tolerance.
Impacts
What was accomplished under these goals?
The group of 725 heifers assessed for thermotolerance during summer 2017, were followed up during December 2017 and were evaluated for body condition scoring, ultrasound backfat and ultrasound rump fat. They also went through a timed AI protocol and their reproductive success was recorded (pregnancy following timed AI, pregnancy by subsequent exposure to natural bull, open at the end of the breeding season). Another set of 875 heifers were from the Seminole Tribe of Florida, Inc. were evaluated under hot and humid conditions during August and September 2018 at the Seminole Ranch, the west of Lake Okeechobee (Brighton Reservation, FL, 27-04'46'' N; 081-04'11'' W). The heifers were randomly assigned to one of four groups and were maintained on pasture for the duration of the study. The first group (n = 200) was monitored from July 25 to July 30, the second group (n = 225) from August 1 to August 5, the third group (n = 224) from August 8 to August 13, and the fourth group (n = 226) from August 15 to August 20, 2016. All heifers within a group were gathered in a coral early in the morning and were individually restrained in a squeeze-chute for insertion of temperature-recording devices and measurement of coat color, coat score, sweating rate, chute score and exit score. Live weight was recorded when heifers were passed through the chute. Two skin biopsies were taken from each heifers, one for histology work and one was dropped in liquid nitrogen for subsequent RNA analysis. For each cow, the average vaginal temperature for 15 minute windows of environmental data were calculated and matched with the measurements of environmental Tdb and THI recorded at the same time. Hourly averages were calculated for environmental measurements and vaginal temperature. Only data recorded during three 24-hour periods starting at 2400 h the day of iButton insertion were used in subsequent analyses to reflect vaginal temperature of cows maintained on pastures without any human interaction.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Hamblen H., A. Zolini, P.J. Hansen, P.A. Oltenacu, and R.G. Mateescu. 2018. Thermoregulatory response of Brangus heifers to naturally occurring heat exposure on pasture. J. Anim. Sci. 96:3131-3137
Dikmen S., R.G. Mateescu, M.A. Elzo, and P.J. Hansen. 2018. Determination of the optimum contribution of Brahman genetics in an Angus-Brahman multibreed herd for regulation of body temperature during hot weather. J. Anim. Sci. 96:21752183.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Coat score and thermotolerance in Bos Indicus influenced cattle. May 30-June 1, 2018. S-1064 Genetic improvement of adaptation and reproduction to enhance sustainability of cow-calf production in the Southern US. Manhattan, KS
Current insights into genomics of thermotolerance in beef cattle. 7th International Symposium on Animal Functional Genomics, Adelaide, Australia, Nov. 12-15, 2018
Genetic parameters for body temperature under hot and humid conditions in an AngusBrahman multibreed population. 11th World Congress on Genetics Applied to Livestock Production, Auckland, NZ, February 11-16, 2018.
Mateescu R.G., Dikmen S., Hansen P.J., and M.A. Elzo. Genetic parameters for body temperature under hot and humid conditions in an AngusBrahman multibreed population. 11th World Congress on Genetics Applied to Livestock Production, Auckland, NZ. Volume Genetic gain - In Challenging Environments, 2018:122. (2018).
Hamblen H., A. Zolini, P.J. Hansen, P.A. Oltenacu, and R.G. Mateescu. Hair coat and thermoregulation in Brangus heifers. Plant and Animal Genome Meeting, San Diego, CA. (2018).
Hamblen H., A. Zolini, P.J. Hansen, P.A. Oltenacu and R.G. Mateescu. (2018). Hair coat and thermoregulation in Brangus heifers on pasture. UF Graduate Student Research Day. Gainesville, FL.
Hamblen H., A. Zolini, M. Gobena, P.J. Hansen and R.G. Mateescu. (2017). Genetics of thermotolerance in Brangus heifers the role of sweating rate and coat score. Proceedings 3rd Annual Research Symposium, UF Animal Sciences Graduate Program, St. Augustine, FL, pg.4.
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Progress 02/01/17 to 01/31/18
Outputs
Target Audience:Researchers in beef cattle and genetics/genomics field, beef cattle producers, stakeholders Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This grant has helped train one PhD students, two Masters students, and four undergraduate students. How have the results been disseminated to communities of interest?The PI of the grant, Raluca Mateescu, gave 8 international and national presentations on the improtance of developing genomic tools for thermotolerance in beef cattle. A particular project overview received national and international interest and generated inteviews with many media sources including BBC Radio. Beef producers and industry stakeholders have also been targeted with online and in-print publications and presenattions during field days and Association Meetings. What do you plan to do during the next reporting period to accomplish the goals?In year two, we will continue our phenotyping for body temperature under heat stress conditions and coat color, coat score, sweating rate, chute score and exit score. We will record additional traits describing the ability of animals to cope with extreme temepratures - skin biopsies will allow us to measure the thickness of the dermis and epidermis, count the number of sweat gleands, measure the depth and volume of the sweat glands. DNA extracted form blood samples will be genotyped with the 250K functional SNP chip and tissues will be stored for further RNA analysis.
Impacts
What was accomplished under these goals?
A total of 725 two-year old Brangus heifers from the Seminole Tribe of Florida, Inc. were evaluated under hot and humid conditions during August and September 2016 at the Seminole Ranch, the west of Lake Okeechobee (Brighton Reservation, FL, 27-04'46'' N; 081-04'11'' W). The heifers were randomly assigned to one of four groups and were maintained on pasture for the duration of the study. The first group (n = 200) was monitored from August 15 to August 19, the second group (n = 189) from August 22 to August 26, the third group (n = 197) from August 29 to September 2, and the fourth group (n = 139) from September 9 to September 12, 2016. All heifers within a group were gathered in a coral early in the morning and were individually restrained in a squeeze-chute for insertion of temperature-recording devices and measurement of coat color, coat score, sweating rate, chute score and exit score. Live weight was recorded when heifers were passed through the chute. There was a large variation in the THI over the time period evaluated, ranging from a minimum of 73 to a maximum of 89. Previous studies suggest that 72 to 79 THI corresponds to mild level of stress, 80 to 89 THI represents moderate level of stress, and a THI greater than 90 is indicative of severe heat stress level. There was also a high level of variation in the vaginal temperature, which ranged overall from 36.6°C to 42.3°C. Most importantly, the variation in the maximum vaginal temperature between 38.8°C and 42.3°C is suggesting that genetic variants controlling body temperature are segregating in Brangus cattle. The coat type had a significant effect on body temperature (P < 0.01), where cows with very smooth coat had significantly lower body temperatures throughout the 3 days of continuous vaginal temperature measurements relative to heifers with a less smooth coat type. These results indicate that coat type plays an important role in the control of core body temperature. A slick dense coat provides a greater resistance to heat transfer to the skin and therefore reduces the heat gain from the environment when the animals is in sunlight. The chute behavior is an indicator of the temperament and the heifers with a calm temperament (CHUTE = 1) were able to maintain a significantly lower (P < 0.015) core body temperature during the entire duration of the experiment. The estimate of the regression coefficient for weight (-0.0011 ± 0.0003) was significantly different from zero (P <.0001) and indicates that heavier heifers are able to maintain a lower core body temperature relative to heifers with lighter weight. The small regression coefficient is somewhat misleading as weight is an important factor with respect to thermotolerance. A difference of 50 kg in live weight has a similar effect on core body temperature as one class difference in the chute score, and 100 kg difference in live body weight has a similar effect as one class difference in the coat score. Two days in both group 2 and 3 had a large difference in their heat-stress load. One day was defined as a high heat-stress load because the THI was greater than 80 (major heat stress) for 11 hours and greater than 85 (critical heat stress) for 6 hours (Figure 1). The other extreme day in both groups had a low heat-stress load with only 7 hours of THI greater than 80 and no THI over 85. Animal response varies according to the intensity and duration of the thermal challenge. Within group 2 and 3, same heifers were exposed to different heat-stress load days which allowed for quantification of the response in vaginal temperature for an increase in THI. The maximum difference (5.99) in THI between these 2 days was recorded at hour 0017. The maximum difference in vaginal temperature (0.68°C) was recorded at hour 0018 indicating that there is an approximately one hour lag in the animal's response to the increase in THI.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Measuring Heat Adaptability in Bos Indicus Cattle. R.G. Mateescu. FRONTLINE Beef Producer October 2017
Hair coat characteristics and heat exchange in beef cattle. Hamblen H. and R.G. Mateescu. The Florida Cattleman & Livestock Journal. October 2017, Vol. 82, No. 1, pg 28-32.
Finding the genetic basis for thermotolerance in beef cattle. R.G. Mateescu., P.J. Hansen, S. Dikemen. The Florida Cattleman & Livestock Journal. Feb. 2017, Vol. 81, No. 5, pg 86-88.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Hamblen H., A. Zolini, M. Gobena, P.J. Hansen and R.G. Mateescu. 2017. Genetics of thermotolerance in Brangus heifers the role of sweating rate and coat score. Proceedings 3rd Annual Research Symposium, UF Animal Sciences Graduate Program, St. Augustine, FL, pg.4.
- Type:
Other
Status:
Other
Year Published:
2017
Citation:
Genomic tools for thermotolerance in beef cattle. Invited talk, 14th International Symposium of Animal Biology and Nutrition, Bucharest, Romania, September 28-29, 2017.
Challenges and opportunities in closing the phenomic gap in cattle. Invited talk, Livestock High-Throughput Phenotyping and Big Data Analytics. National Agricultural Library. Beltsville, MD. November 13-14, 2017.
Use of Genomics to Improve Climate Adaptability and Carcass Merit. Invited talk, International Brangus Breeders Association (IBBA) Fall Conference & Southeast Brangus Breeders Association (SBBA) Field Day, Seminole Indian Reservation, Brighton, FL. August 17-19, 2017.
Measuring Adaptability in Cattle. Invited talk, Beef Cattle Short Course TAMU. College Station, TX. August 6-7, 2017.
Beef cattle climate adaptability: how can genomics help? Invited talk, Beef Improvement Federation Convention, Athens, GA, May 31 June 3, 2017.
Genomic tools for beef cattle improvement. Invited talk, Levy County Cattlemen's Association Meeting, Whitehurst Cattle Company, FL, October 26, 2017.
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