Genotype by environment interaction for somatic cell score in Holstein cattle of southern Brazil via reaction norms

Abstract

Objective: The objective of this study was to evaluate the genetic behavior of a population of Holstein cattle in response to the variation of environmental temperature by analyzing the effects of genotype by environment interaction (GEI) through reaction norms for the somatic cell score (SCS).Methods: Data was collected for 67,206 primiparous cows from the database of the Paraná Holstein Breeders Association in Brazil, with the aim of evaluating the temperature effect, considered as an environmental variable, distinguished under six gradients, with the variation range found being 17°C to 19.5°C, over the region. A reaction norm model was adopted utilizing the fourth order under the Legendre polynomials, using the mixed models of analysis by the restricted maximum likelihood method by the WOMBAT software. Additionally, the genetic behavior of the 15 most representative bulls was assessed, in response to the changes in the temperature gradient.Results: A mean score of 2.66 and a heritability variation from 0.17 to 0.23 was found in the regional temperature increase. The correlation between the environmental gradients proved to be higher than 0.80. Distinctive genetic behaviors were observed according to the increase in regional temperature, with an observed increase of up to 0.258 in the breeding values of some animals, as well as a reduction in the breeding of up to 0.793, with occasional reclassifications being observed as the temperature increased.Conclusion: Non-relevant GEI for SCS were observed in Holstein cattle herds of southern Brazil. Thus, the inclusion of the temperature effect in the model of genetic evaluation of SCS for the southern Brazilian Holstein breed is not required.

Additive genetic and permanent environmental correlation between different parts of lactation in moderate and cold regions

“…Except for the beginning of lactation, the increasing permanent environmental variance during lactation indicates the importance of non-genetic factors on SCS. The results of this study, similar to other studies (Koivula et al 2005;Mulim et al 2021), revealed that SCS is strongly affected by the temporary environmental variance.…”

“…A reason for the existence of G × E interaction and low genetic correlation between the moderate and cold climate is the influence of environmental effects on this trait especially in early lactation. Mulim et al (2021) Ismael et al (2016) concluded that genetic correlations of time from calving to first insemination were close to unity, indicating no genotype by environment interaction between different geographic locations. On the other hand, genetic correlations less than unity were reported between calving seasons for days open in the US Holstein cows (Oseni et al 2004) and for age at first calving between Brazil and Colombia (Ceron-Munoz et al 2004).…”

Genotype by Environment Interaction and Selection Response for Milk Yield Traits and Conformation in a Local Cattle Breed Using a Reaction Norm Approach

“…The degree of reranking of bulls is a widespread criterion to establish if the introduction of GxE is useful for routine selection practice or not: e.g., minor reranking of bulls for fat and protein yield [ 80 ] and for SCS [ 27 ] was observed in Brazilian Holstein bulls, suggesting non-relevant GxE. Despite a higher genetic response under intensive herd management, no reranking was found in French Holstein, Normande and Montbéliarde, despite a higher genetic response under intensive herd management [ 33 ].…”

“…Many studies have considered climate characteristics such as temperature-humidity variation as an environmental covariate in modelling (e.g., [ 24 ]), but other conditions such as herd management (e.g., [ 25 ]) or average production level (e.g., [ 26 ]) can also be considered. Reaction norm can be modelled using a single-step or two step analysis: the first is generally used when a climatic descriptor such as temperature or the temperature-humidity index (THI) is directly used as an environmental covariate [ 8 , 24 , 27 ], whereas a two-steps model is applied when herds of similar conditions (often called contemporary groups) are considered as an environmental gradient [ 11 , 28 , 29 ]. This last form of modelling is particularly useful when various geographical and farm-management conditions characterize the rearing systems in a breed, such as in Brown Swiss of Germany and Austria [ 10 ], and Rendena [ 30 ], which is the study subject.…”

Genotype by Environment Interactions in Livestock Farming

“…Similarly, Gerber et al [31], Huquet et al [32], Calus et al [21], and Schmid et al [33] studied macro-environmental plasticity for production traits in German Simmental, French Holstein, Dutch Holstein Friesian cattle, and German Brown Swiss cattle, defining the environmental conditions with different management parameters. Similarly, Santos et al [34] and Mulim et al [35,36] studied production traits in Brazilian Holstein, and Bohlouli et al [37] studied production traits as well as milk fat composition in German Holstein.…”