Inbreeding and pedigree structure in Standardbred horses

Carneiro

et al. 2010

Pesq. agropec. bras.

-The objective of this work was to evaluate the population structure and the genetic and phenotypic progress of Nelore cattle in Northern Brazil. Pedigree information concerning animals born between 1942 and 2006 were analyzed. Population structure was performed using the Endog program. Out of the 140,628 animals studied, 67.7, 14.52 and 3.18% had complete pedigree record of the first, second and third parental generation, respectively. Inbreeding and average relatedness coefficients were low: 0.2 and 0.13%, respectively. However, these parameters may have been underestimated, since information on pedigree was incomplete. The effective number of founders was 370 and the genetic contribution of 10, 50 and 448 most influent ancestors explained 13.2, 28 and 50% of the genetic variability in the population, respectively. The genetic variability for growth traits and population structure demonstrates high probability of increasing productivity through selective breeding. Moreover, management strategies to reduce the currently observed age at first calving and generation intervals are important for Nelore cattle genetic improvement.Index terms: Bos taurus indicus, effective population size, genetic parameters, genetic trends, inbreeding, pedigree analysis. Melhoramento genético e estrutura populacional da Raça Nelore na Região Norte do BrasilResumo -O objetivo deste trabalho foi avaliar a estrutura populacional e o progresso genético e fenotípico da raça Nelore na Região Norte do Brasil. Informações sobre o pedigree foram analisadas em animais nascidos entre 1942 e 2006. A estrutura populacional foi estimada utilizando-se o programa Endog. Dos 140.628 animais avaliados, 67,7% dos pais, 14,52% dos avós e 3,18% dos bisavós eram conhecidos. O coeficiente de parentesco médio e a endogamia foram, em geral, baixos: 0,13 e 0,20%, respectivamente. Contudo, esses parâmetros podem ter sido subestimados, já que as informações de pedigree eram incompletas. O número efetivo de fundadores foi de 370 e a variabilidade genética na população explicada pelos 10, 50 e 448 mais influentes ancestrais foi de 13,2, 28 e 50%, respectivamente. A existência de variabilidade genética indica possibilidade de aumento na produtividade por meio da seleção. Adicionalmente, estratégias de manejo para diminuir a idade ao primeiro parto e o intervalo de gerações são importantes para o melhoramento da raça.Termos para indexação: Bos taurus indicus, tamanho efetivo da população, parâmetros genéticos, tendência genética, endogamia, análise de pedigree.

Section: Methodsmentioning

confidence: 99%

Genetic improvement and population structure of the Nelore breed in Northern Brazil

Carneiro

et al. 2010

Pesq. agropec. bras.

“…The SB, on the other hand, has always been selected for trotting and pacing speed (e.g. MacCluer et al, 1983) and other traits important in harness racing.…”

Section: Pedigrees and Inbreedingmentioning

confidence: 99%

Effects of inbreeding and other genetic components on equine fertility

Sairanen

Nivola

Katila

et al. 2009

Animal

The Finnish mating records of Standardbred trotters (SB; n 5 33 679) and Finnhorses (FH; n 5 32 731) were analysed to study the effect of the level of inbreeding on foaling rates and to estimate the heritability of foaling rate. A linear mixed model was assumed, with the outcome of the foaling (foal or no foal) as the trait of the study. A restricted maximum likelihood-based method was used to calculate the estimates of the variance components. Predictions of breeding values and estimates of fixed effects were also calculated. The average level of inbreeding was 9.9% in the SB and 3.6% in the FH. The average foaling rates were better in the SB (72.6%) than in the FH (66.3%), but within each breed intense inbreeding had a statistically significant negative effect on foaling rate ( P , 0.05). Also, the mating type, the age and breeding type of the mare, and the age of the stallion had statistically significant effects on foaling rate ( P , 0.001). The heritability of foaling rate was between 3.4% and 3.7% in SBs and between 5.5% and 9.8% in FHs, when the outcome of the foaling was considered to be a trait of the expected foal. With the same model, the estimates of maternal genetic effect were 4.7% for SBs and 3.2% for FHs, and the estimates of the permanent environmental effects of the stallion were between 1.3% and 1.7%. Avoiding matings with very high inbreeding coefficients would improve foaling rates. It would also be possible to devise a breeding program for better equine fertility, but because the heritability is low, improvement of environmental factors deserves special attention.

“…RDN were therefore present in both datasets, and consequently, 12,709 animals were common to both pedigrees. The completeness of pedigree [17] was computed for all animals to ascertain the proportion of known ancestors per generation. Additionally, the number of equivalent complete generations known in the pedigree was computed as the sum over all known ancestors of the term (1/2) n , where n is the number of generations separating the individual from each known ancestor [18].…”

Section: Introductionmentioning

confidence: 99%

Genetic Diversity and Ancestral History of the German Angler and the Red-and-White Dual-Purpose Cattle Breeds Assessed through Pedigree Analysis

Addo¹,

Schäler²,

Hinrichs³

et al. 2017

Local cattle breeds continue to decline in numbers partly due to the use of high performing breeds in advanced production systems where genetic material of elite animals is widely spread. The objective of this study was to assess the within and across breed genetic diversity of the Angler and Red-andWhite dual-purpose (DP) cattle breeds applying different inbreeding concepts. Classical and ancestral inbreeding coefficients were computed from pedigree data using the gene dropping method. Effective population size was calculated based on the increase of classical inbreeding, and based on ancestral inbreeding to obtain what was termed as ancestral effective population size. Furthermore, the effective number of founders and ancestors were computed to assess the disequilibrium of founder contribution in the reference populations. The analyses were performed separately for each breed and for a combined dataset. The Angler pedigree was more complete (88%) in the first parental generation but completeness declined with increasing pedigree depth. Average classical inbreeding coefficients of inbred individuals were 2.19%, 1.94% and 2.07%, while average Ballou's ancestral inbreeding coefficients were 3.69%, 1.39% and 2.21% for the Angler, Red-and-White DP and the combined breed pedigree analyses, respectively. Ancestral history coefficient is a novel coefficient and its estimates were similar and strongly correlated to Ballou's coefficients (r = 0.99, p < 0.001). The effective population size estimates ranged from 156 to 170 for the classical inbreeding based method, and as low as from 50 to 54 for the ancestral history coefficient based method. The effective number of founders and ancestors ranged from 310 to 532, and