Genetic Diversity of Lusitano Horse in Brazil Using Pedigree Information

Abstract

This study aimed to evaluate population parameters and to describe the genetic diversity of the Lusitano breed in Brazil using pedigree data. Two populations were evaluated: total population (TP) containing 18,922 animals, and reference population (RP) composed of a part of TP containing 8,329 animals, representing the last generation. The generation interval (10.1 ± 5.1 years) was in the range for horse populations. Pedigree completeness in RP shows almost 100% filling in the three most recent generations, indicating improvement in the pedigree data and accuracy of the results, and the inbreeding coefficient (4.46%) and average relatedness (5.97%) for RP, indicating control on the part of breeders. The effective population size was 89 (TP) and 90 (RP). The effective number of founders (f e) were 33 and 29, effective number of ancestors (f a) were 30 and 26, and effective number of founder genomes (f g) were 19 and 15 for TP and RP, respectively, indicating a reduction of genetic variability in the last generations. The total number of ancestors that explains 100% of the genetic diversity in the Lusitano breed in Brazil was 427 (TP) and 341 (RP). The reproductive parameters, probabilities of gene origin showing loss of variability in the last generations, and the genetic contributions of ancestors suggest the need to monitor genetic diversity over time in breeding programs to allow control of the next generations and to increase their variability.

500 years of breeding in the Carthusian Strain of Pura Raza Español horse: An evolutional analysis using genealogical and genomic data

“…The values of the GCI (Table 1) are in accordance with the value of 11.14 obtained in a previous work in the PRE breed including CS (Poyato-Bonilla et al, 2018). In recent literature, a slightly lower (9.60) index has been reported in a related breed, such as Lusitano (da Silva Faria et al, 2018). The evolution of GCI in the PRE_CI_NC and PRE_C has been the opposite since 1980 (Figure 1c): the number of founders contributing to PRE_CI_NC horses has increased, while this parameter has decreased in the PRE_C.…”

“…Genetic conservation index (GCI) has seen a similar evolution in both PRE_CI_NC and PRE_C subpopulations: over the last decades, a great change has been detected. At the individual level, GCI is a particularly important parameter in genetic conservation programmes, as horses with higher indexes exhibit a greater balance in the number of founders and should be used preferentially in the choice of breeding animals to maintain the genes transmitted by founders (da Silva Faria et al, 2018). The values of the GCI (Table 1) are in accordance with the value of 11.14 obtained in a previous work in the PRE breed including CS (Poyato-Bonilla et al, 2018).…”

“…The reliability of these estimates is often conditioned by the quality of the pedigree. Here, the pedigree completeness, studied across equivalent complete generations, with a mean value of 8.42 in PRE_C (9.01 on average in the whole population), far exceeds the values of other important Spanish horse populations such as Spanish Sport Horse (5.31), Anglo Arab Horse (5.50) or Spanish Trotter Horse (3.87) (Gómez et al, 2020), and also of Lusitano (5.70) (da Silva Faria et al, 2018). The Lipizzan horse, a breed derived from ancient PRE horses, presented a value of the same magnitude, with 10.25 EqG (Pjontek et al, 2012).…”

“…Previous studies in other equine breeds related to PRE estimated F average values of 4.06% in the Lusitano horse (da Silva Faria et al, 2018) and 10.8% in the Lipizzan horse, with a population size quite similar to the PRE_C subpopulation (Zechner et al, 2002). AR values in these breeds were lower: 3.73% and 5.41%, for Lipizzan and Lusitano horse, respectively (Pjontek et al, 2012;da Silva Faria et al, 2018).…”

Genetic Structure Analysis of the Pura Raza Español Horse Population through Partial Inbreeding Coefficient Estimation

“…The Lusitano horse breed shows a mean F value of 9.92% and a number of equivalent generations of 9.87 [27], while the Lipizzan horse, with 15.22 complete equivalent generations, shows a mean F of 10.8% [28]. In addition, despite the fact that the Lusitano is a closed and inbred breed, the care taken by breeders to maintain the genetic variability, as the case of the Lusitano horse in Brazil, make their level of inbreeding lower than the total population, especially in the last generation with a mean F of 4.46% and a number of equivalent generations of 6.4 [29].…”