Genetic analysis of the effects of heat stress before and after lambing on pre-weaning live weight in Spanish Merino lambs

Background: Heat stress (HS) is a major environmental effect on sheep production. Hereby, we estimated the genetic (co)variance component of HS on the pre-weaning performance of 19,022 Merino lambs by analysing the climatological index of temperature and relative humidity (recorded 30 days before lambing and after lambing) using transversal and longitudinal mixed linear models. Methods and Results: The global impact of HS during the last 30 days of pregnancy was −17% for birthweight and ranged between −4% and −8% for live weight at 15, 30 days of age (W30), and average daily gain from birth at 30 days. The results from both statistical approaches showed very similar heritabilities (h2), ranging from 0.192 to 0.237 for the direct genetic (D) effects and from 0.072 to 0.082 for the maternal genetic (M) effects, but the antagonism between (D) and (M) was higher when a longitudinal model was used. A significant genotype-environmental effect was also found regardless of whether the climatological covariables were considered in the model. In addition, we employed D and M breeding values for W30 as an example to create a new subjacent index by first using a principal component analysis and employing the leading eigenvalues as a weighted factor that provides the information needed to identify those genotypes that maximise the response for both genetic effects over a wide range of climate–environment levels. Conclusions: Our study revealed that the HS indexes of the mother during the gestation period have a significant effect on the growth of the lambs during the early stages of life.Fil: Molina, Antonio. Universidad de Córdoba; EspañaFil: Demyda-peyrás, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Sánchez, Manuel. Universidad de Córdoba; EspañaFil: Serradilla, Juan M.. Universidad de Córdoba; EspañaFil: Menéndez Buxadera, Alberto. Universidad de Córdoba; Españ

Characterisation of Goats’ Response to Heat Stress: Tools to Improve Heat Tolerance

This chapter aims to review present knowledge about the effects of heat stress on goats, summarising what is known about its measurement, its impact on the performances of the animals, mainly milk traits, the physiological and genetic bases of the animals’ response and the improvement of resilience through selection. A short historic review of the climatic indexes used to measure heat stress, with special emphasis on the temperature humidity indexes, and the main consequences on milk yield and composition are followed by a description of the results of experiments carried out to study the physiological and metabolic consequences of heat stress. The results of the quantitative analyses of the genetic bases of heat stress using norm of reaction models and of the application of omic techniques, particularly transcriptomic and genomic, to understand the complexity of the genetic background of animal’s reaction to thermal stress, constitute the next points. The chapter ends treating the possible ways and difficulties of applying selection to increase resilience to heat stress

Efeito genético de estações climáticas no crescimento pré-desmame de bovinos de corte: uma primeira abordagem para os bezerros Retinta

Background: Heat stress derived from global warming is causing major economic losses in the livestock industry. Objective: To develop a novel methodological approach for determining the influence of climatic factors on the estimation of genetic parameters for growth traits in Retinta cattle breed by using reaction-norm models. Methods: Live weight records (n=7,753) from 3,162 Retinta calves born from 1,249 dams and 85 sires and raised in the Andalusian region (Spain) were analyzed. The effect of heat stress was measured using the temperature-humidity index, calculated with climatological data obtained from four weather stations. A bivariate-random-regression reaction-norm model was used to estimate the (co)variance components of weight until weaning in two different climatic seasons corresponding to warm and cold months. Results: The heritability pattern of individuals reared under diverse environments during the first 90 days of age was different. However, differences were not significant at the end of the growing period. Weaned calves reared during the cold season showed greater growth from 70 to 160 days in comparison with those reared during the warm season. Conclusions: Overall, this assessment did not show significant effects of the genotype-environment interaction. However, highly significant evidence of genotype-climatic condition interaction was found during the calf´s first three months of age.Antecedentes: El estrés térmico derivado del calentamiento global está causando pérdidas económicas en la industria ganadera. Objetivo: Desarrollar un enfoque metodológico para estimar la influencia de algunos factores climáticos sobre la estimación de parámetros genéticos en las variables de crecimiento de la raza bovina Retinta. Métodos: Se analizaron registros de peso vivo (n=7.753) de 3.162 terneros hijos de 1.249 vacas y 85 toros, criados en la región de Andalucía (España). El efecto del estrés térmico se midió mediante un índice de temperatura-humedad obtenido a partir de los datos de cuatro estaciones meteorológicas. Se usó un modelo bivariado de regresión aleatoria de “norma-reacción” para estimar la (co)varianza del peso hasta el destete en dos diferentes épocas climáticas correspondientes a los meses cálidos y fríos. Resultados: Se encontraron diferencias en el patrón de heredabilidad de individuos criados en diferentes ambientes durante los primeros 90 días de vida. Sin embargo, tales diferencias no fueron significativas al final del periodo de crecimiento. Los terneros destetados en la época fría mostraron un mayor crecimiento entre 70 y 160 días en comparación con los criados en la temporada cálida. Conclusiones: Se encontró una evidencia altamente significativa de la interacción genotipo-condición climática durante los primeros tres meses de crecimiento del ternero.Antecedentes: O estresse térmico devido ao aumento da temperatura média está produzindo grandes perdas econômicas na indústria pecuária. Objetivo: Realizar uma nova abordagem metodológica para estimar a importância dos fatores climáticos em parâmetros genéticos em variáveis de crescimento da população da raça Retinta. Métodos: Foram analisados registros de peso vivo (n=7.753) de 3.162 Retinta bezerros, nascidos de 1.249 vacas e 85 touros criados na região da Andaluzia (Espanha). O efeito do estresse térmico foi medido utilizando o índice de temperatura-umidade obtido com dados climatológicos de quatro estações meteorológicas. Um modelo de regressão aleatória bivariado de norma-reação foi usado para estimar os componentes da (co)variância do peso à desmama em duas estações climáticas com correspondência aos meses quentes e fríos. Resultados: Diferenças foram encontradas no padrão de herdabilidade de indivíduos criados em diferentes ambientes nos primeiros 90 dias de idade. No entanto, essas diferenças não foram significativas no final do período de crescimento. Os bezerros desmamados globalmente na estação fria apresentaram um crescimento maior dos 70 aos 160 dias em comparação com os indivíduos criados na estação quente. Conclusões: Uma evidência altamente significativa da interação genótipo-ambiente foi encontrada durante os primeiros três meses de crescimento do bezerro.Instituto de Genética Veterinari

Effect of αs1-casein (CSN1S1) genotype on milk CSN1S1 content in Malagueña and Murciano-Granadina goats

There is substantial evidence showing that the polymorphism of the goat αs1-casein (CSN1S1) gene has a major effect on milk protein, casein and fat content as well as on cheese yield. However, its influence on the synthesis rate of CSN1S1 has been less studied, with measurements only available in French breeds. In this article, we have measured milk CSN1S1 content in 89 Malagueña and 138 Murciano-Granadina goats with 305 and 460 phenotypic registers, respectively. In the Malagueña breed, average values of CSN1S1 content estimated for BB, BF, EE and FF genotypes were 6·94±0·38, 5·36±0·22, 4·58±0·13 and 3·98±0·27 g/l, respectively, being all significantly different (P<0·05). Conversely, in the Murciano-Granadina breed only the BB genotype (8·50±0·60 g/l) was significantly associated with increased levels of CSN1S1 (P<0·05), whereas BF (6·56±0·82 g/l), EE (6·39±0·60 g/l) and EF (6·91±0·76 g/l) genotypes displayed non-significant differences when compared with each other. Our results highlight the existence of breed-specific genetic and/or environmental factors modulating the impact of the CSN1S1 gene polymorphism on the synthesis rate of the corresponding protein.This work was funded with grants from the Spanish Ministry of Education and Science (1FD1997-1052-C02-01 and AGL2002- 04304-C03-02-GAN).Peer reviewe

Use of Principal Component Analysis to Combine Genetic Merit for Heat Stress and for Fat and Protein Yield in Spanish Autochthonous Dairy Goat Breeds

We studied the effect of the Temperature Humidity Index (THI) (i.e., the average of temperature and relative humidity registered at meteorological stations) closest to the farms taken during the test day (TD), for total daily protein and fat yields (fpy) of the three main Spanish dairy goats. The data were from Florida (11,244 animals and 126,825 TD), Malagueña (12,215 animals and 141,856 TD) and Murciano Granadina (5162 animals and 62,834 TD) breeding programs and were studied by different linear models to estimate the nature of the fpy response throughout the THI and the weeks of lactation (Days in Milk, DIM) trajectories. The results showed an antagonism between THI and DIM, with a marked depression in the fpy level in animals kept in the hot zone of the THI values (THI &gt; 25) compared with those in the cold zone (THI ≤ 16), with a negative impact equivalent to production of 13 to 30 days. We used a Reaction Norm model (RN), including THI and DIM as fixed covariates and a Test Day Model (TDM), to estimate the genetic (co)variance components. The heritability and genetic correlations estimated with RN and TDM showed a decreased pattern along the scale of THI and DIM, with slight differences between breeds, meaning that there was significant genetic variability in the animal’s ability to react to different levels of THI, which is not constant throughout the DIM, showing the existence of genotype-environment interaction. The breeding values (BV) of all animals for each level of THI and DIM were subject to a principal component analysis, and the results showed that 89 to 98% of the variance between the BV was explained by the two first eigenvalues. The standardized BV were weighted with the corresponding eigenvector coefficients to construct an index that showed, in a single indicator, the most complete expression of the existing genetic variability in the animals’ ability to produce fpy along the trajectories of THI and DIM. This new option will make it easier to select animals which are more productive, and with better adaptability to heat stress, as well as enabling us to exploit genetic variations in the form of the response to heat stress to be adapted to different production systems

ANÁLISIS COMPARATIVO DE LA REPETIBILIDAD PARA PRODUCCIÓN DE LECHE EN GANADO HOLSTEIN PURO O CRUZADO CON BROWN SWISS Y JERSEY EN LA CUENCA LECHERA DE CHIRIQUÍ

Periodic milk (TD) records (265,080) were obtained from pure Holstein cows crossed with Brown Swiss or Jersey from two herds in the Chiriquí dairy basin between 1996 and 2016. Initially, a mixed linear model was applied to know the factors that affect milk production and plot response curves along the lactation path and number of deliveries. Subsequently, a longitudinal repeatability model (REP) and a random regression model (RA) were applied. The effects included in the models were highly significant (p &lt;0.0001). The lactation curve presented a typical behavior, with the peak between 50 to 60 days post-partum and a higher productivity of Jersey crosses compared to Brown Swiss. The values of third lactation onwards did not show differences between them, with levels higher than the first two. The repeatability estimates according to the REP model were 0.577 ± 0.02; 0.675 ± 0.02 and 0.628 ± 0.01 for the crossbred animals of Brown Swiss, Jersey and pure Holstein respectively. According to the RA model, the estimates were lower and showed that there is heterogeneity in their behavior throughout lactation. The correlations between the TDs at different points of lactation showed that the control day models can be biased by assuming that the correlations are equal to unity. The work carried out showed some advantages that the use of crossbreeding can provide to increase the productive levels of dairy cattle in the studied region.Se dispuso de 265080 registros periódicos de leche (TD) de vacas Holstein puras y cruzadas con Brown Swiss o Jersey de dos rebaños en la cuenca lechera de Chiriquí entre 1996 y 2016. Inicialmente, se aplicó un modelo lineal mixto para conocer los factores que afectan la producción de leche y representar curvas de respuesta a lo largo de la trayectoria de la lactancia y del número de partos. Posteriormente se aplicó un modelo longitudinal de repetibilidad (REP) y uno de regresión aleatoria (RA). Los efectos incluidos en los modelos fueron altamente significativos (p&lt;0.0001). La curva de lactancia presentó un comportamiento típico, con el pico entre los 50 a 60 días post parto y una productividad mayor de los cruces Jersey respecto a los Brown Swiss. Los valores de tercera lactancia en adelante no manifestaron diferencias entre sí, con niveles superiores a las dos primeras. Los estimados de repetibilidad según el modelo REP fueron de 0.577±0.02; 0.675±0.02 y 0.628±0.01 para los animales cruzados de Brown Swiss, Jersey y Holstein puro respectivamente. Según el modelo RA los estimados fueron inferiores y demostraron que existe heterogeneidad en su comportamiento a lo largo de la lactancia. Las correlaciones entre los TD a diferentes puntos de la lactancia mostraron que los modelos del día de control pueden ser sesgados al asumir que las correlaciones son iguales a la unidad. El trabajo realizado demostró algunas ventajas que puede proporcionar el uso del cruzamiento para incrementar los niveles productivos del vacuno lechero en la región estudiada. &nbsp

Genetic (co)variance and plasticity of behavioural traits in Lidia bovine breed

Scores for four behavioural traits – aggressiveness, ferocity, face hiding and nobility – recorded between 1984 and 2010 in Lidia bovine breed (the property of a single breeder in Spain), were analysed using the multi-trait and reaction norm models. The multi-trait analysis results revealed heritability values of between 0.23 for nobility and 0.33 for ferocity. Principal components analysis of the genetic correlation matrix identified two factors that explained 91.6% of the total variance. Reaction norm analysis revealed genetic correlation values across sexes and time to be <|1|; this indicates the existence of an interaction genotype x environment. Plasticity, defined as the difference between breeding values over time periods and across the sexes, can be a useful tool for taking into account the influence of the environment on the breeding goal. This allows this interaction to be managed within the framework of a selection programme. With the exception of aggressiveness, which showed significant plasticity, the behaviour of the traits was robust over time and across the sexes. This methodology therefore allows the detection of groups of animals with more robust or plastic responses, particularly with respect to aggressiveness. The use of plasticity as a selection criterion might be beneficial in Lidia bovine breed breeding programmes

Análisis genético del desarrollo en peso vivo y tasa de gestación en primer parto en bovinos Brahman de Venezuela

El peso vivo (PV) de 2,777 animales (1,377 hembras y 1,400 machos con 53,258 datos individuales entre 30 y 600 días de edad), nacidos entre febrero de 2000 y junio del 2011, se analizaron con un modelo de regresión aleatoria (RA) para estimar los componentes genéticos de (co)varianza a lo largo de la escala edad-sexo. La tasa de gestación (TG) junto con el peso vivo ajustado a 548 días de edad (PA548) se estudiaron mediante un modelo multicaracter (MT) obteniéndose un incremento en los estimados de heredabilidad (h2) para TG respecto al clásico modelo univariado (0.08 ± 0.03 vs 0.11 ± 0.02), aumentando la precisión del valor genético (VG) para TG en 15.7 %. La correlación genética (rg) entre TG y PA548 fue 0.31 ± 0.11. El RA mostró que el PV a través de la edad no puede considerarse como expresión del mismo rasgo en ambos sexos, ya que las rg fueron inferiores a 0.60. El análisis de componentes principales mostró que existen cambios importantes en la forma de crecimiento de los animales en la escala de edad representada en estos datos. Se manifestó un importante dimorfismo de origen genético, estimado como diferencia de los VG de machos y hembras en PV, el cual presenta una relación positiva con los VG de la TG

INFLUENCIA DE FACTORES AMBIENTALES EN LA PRODUCCIÓN DE LECHE DE DOS REBAÑOS HOLSTEIN EN LA CUENCA LECHERA DE CHIRIQUÍ

The aim of the study was to measure the effect of some environmental factors in the milk production of two Holstein herds in the Chiriquí dairy basin, including milk weighing (PDC) among 1996 and 2016. The environmental temperature was obtained from two weather stations near the herds. A mixed model was applied with sire as a random effect. It was analyzed the effect of herd, age at birth, number of births, temperature and interactions among them on the PDC. The model showed differences (p &lt;.0001) for all the effects included. The average daily production was 22.30 kg / day and 6774.05 kg accumulated at 305 days. The duration of breastfeeding was 349 ± 93 days. The effects of age at birth on daily milk production showed a pattern of sustained increases until six years of age (third birth). Herd one doubled its production while in herd two in which the increases were of the order of 40%. Two thermal zones were identified in relation to maximum temperature, first called tolerance zone where no significant effects in milk production, and another zone called thermal stress (ST) with a regression coefficient -0.268, and 42.6% of the PDC records were measured under ST conditions. It is concluded that the environmental factors evaluated affected milk production and should be considered in genetic evaluation programs for the studied area.Para estudiar el efecto de algunos factores ambientales en la producción de leche se dispuso de los pesajes de leche (PDC) de dos rebaños Holstein en la cuenca lechera de Chiriquí que comprendió los años 1996-2016. La temperatura ambiental se obtuvo de dos estaciones meteorológicas próximas a los rebaños. Se aplicó un modelo mixto con el padre como efecto aleatorio. Se analizó la influencia de los efectos de rebaño, edad al parto, número de partos, temperatura e interacciones entre ellos en las PDC. Los resultados mostraron diferencias (p&lt;.0001) para todos los efectos incluidos. La producción diaria promedio fue de 22,30 kg/día y acumulado a 305 días de 6774,05 kg. La duración de la lactancia fue de 349 ± 93 días. Los efectos de edad al parto en la producción diaria de leche mostraron un patrón de aumentos sostenido hasta los seis años de edad (tercer parto). El rebaño uno duplicó su producción mientras que en el rebaño dos se incrementó en 40%. Se identificaron dos zonas con relación a temperatura máxima, una de tolerancia donde no se manifestaron efectos importantes en la producción de leche, y otra de estrés térmico con un coeficiente de regresión de -0,268, y donde el 42,6% de los registros de PDC fueron medidos en condiciones de estrés térmico. Se concluye que los factores ambientales evaluados afectaron la producción de leche y deben ser considerados al implementar programas de evaluación genética para la zona estudiada

Influencia de factores ambientales en la producción de leche de dos rebaños Holstein en la cuenca lechera de Chiriquí

Para estudiar el efecto de algunos factores ambientales en la producción de leche se dispuso de los pesajes de leche (PDC) de dos rebaños Holstein en la cuenca lechera de Chiriquí que comprendió los años 1996-2016. La temperatura ambiental se obtuvo de dos estaciones meteorológicas próximas a los rebaños. Se aplicó un modelo mixto con el padre como efecto aleatorio. Se analizó la influencia de los efectos de rebaño, edad al parto, número de partos, temperatura e interacciones entre ellos en las PDC. Los resultados mostraron diferencias (p<.0001) para todos los efectos incluidos. La producción diaria promedio fue de 22,30 kg/día y acumulado a 305 días de 6774,05 kg. La duración de la lactancia fue de 349 ± 93 días. Los efectos de edad al parto en la producción diaria de leche mostraron un patrón de aumentos sostenido hasta los seis años de edad (tercer parto). El rebaño uno duplicó su producción mientras que en el rebaño dos se incrementó en 40%. Se identificaron dos zonas con relación a temperatura máxima, una de tolerancia donde no se manifestaron efectos importantes en la producción de leche, y otra de estrés térmico con un coeficiente de regresión de -0,268, y donde el 42,6% de los registros de PDC fueron medidos en condiciones de estrés térmico. Se concluye que los factores ambientales evaluados afectaron la producción de leche y deben ser considerados al implementar programas de evaluación genética para la zona estudiada