Abstract
Non‐genetic information (epigenetic, microbiota, behaviour) that results in different phenotypes in animals can be transmitted from one generation to the next and thus is potentially involved in the inheritance of traits. However, in livestock species, animals are selected based on genetic inheritance only. The objective of the present study was to determine whether non‐genetic inherited effects play a role in the inheritance of residual feed intake (RFI) in two species: pigs and rabbits. If so, the path coefficients of the information transmitted from sire and dam to offspring would differ from the expected transmission factor of 0.5 that occurs if inherited information is of genetic origin only. Two pigs (pig1, pig2) and two rabbits (rabbit1, rabbit2) datasets were used in this study (1,603, 3,901, 5,213 and 4,584 records, respectively). The test of the path coefficients to 0.5 was performed for each dataset using likelihood ratio tests (null model: transmissibility model with both path coefficients equal to 0.5, full model: unconstrained transmissibility model). The path coefficients differed significantly from 0.5 for one of the pig datasets (pig2). Although not significant, we observed, as a general trend, that sire path coefficients of transmission were lower than dam path coefficients in three of the datasets (0.46 vs 0.53 for pig1, 0.39 vs 0.44 for pig2 and 0.38 vs 0.50 for rabbit1). These results suggest that phenomena other than genetic sources of inheritance explain the phenotypic resemblance between relatives for RFI, with a higher transmission from the dam's side than from the sire's side.
Highlights
Phenotypic resemblance between relatives, that forms the basis of some selection strategies, is not solely due to the transmission of DNA from one generation to the one
The LRT that compared the animal and the transmissibility models showed that the null hypothesis “sire and dam path coefficients of transmission are equal to 0.5” (i.e., residual feed intake (RFI) is transmitted by genetic inheritance only) was rejected for the pig2 dataset only
It has been shown that, to a model that aims at dissociating genetic from non-genetic inherited effects, the parameters of the transmissibility model are practically identifiable in most situations, which is its main advantage (David & Ricard, 2019)
Summary
Phenotypic resemblance between relatives, that forms the basis of some selection strategies, is not solely due to the transmission of DNA from one generation to the one. Behavioural/cultural inheritance is the transmission of information from one individual to another via learning mechanisms Such non-genetic vertical transmission of behavioural characters has been demonstrated in various animal species, especially rodents (Champagne, 2008). The impact of these non-genetic sources of inheritance on the phenotypic variability of traits of economic importance in livestock species has rarely been investigated This is mainly due to the difficulty of disentangling the different sources of inheritance with only pedigree and phenotype data, and the lack of appropriate data structure (large variety of different categories of relatives with phenotype) (David & Ricard, 2019). To the animal model, the transmissibility model uses pedigree and phenotypic information to estimate variance components and predict a transmissible potential for an individual that combines all sources of inheritance. It differs from the animal model by estimating the path coefficients of inherited information from parent to offspring instead of using the pedigree-based expected transmission factor of 0.5 for both the sire and the dam (additive genetic relationship matrix)
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