RESUMEN
Missing pedigree may produce bias in genomic evaluations. Thus, strategies to deal with this problem have been proposed as using unknown parent groups (UPG) or truncated pedigrees. The aim of this study was to investigate the impact of modeling missing pedigree under ssGBLUP evaluations for productive and reproductive traits in dairy buffalos using different approaches: 1) traditional BLUP without UPG (BLUP), 2) traditional BLUP including UPG (BLUP/UPG), 3) ssGBLUP without UPG (ssGBLUP), 4) ssGBLUP including UPG in the A and A22 matrices (ssGBLUP/A_UPG), 5) ssGBLUP including UPG in all elements of the H matrix (ssGBLUP/H_UPG), 6) BLUP with pedigree truncation for the last 3 generations (BLUP/truncated), and 7) ssGBLUP with pedigree truncation for the last 3 generations (ssGBLUP/ truncated). UPGs were not used in the scenarios with truncated pedigree. A total of 3,717, 4,126 and 3,823 records of the first lactation for accumulated 305 d milk yield (MY), age at first calving (AFC) and lactation length (LL), respectively were used. Accuracies ranged from 0.27 for LL (BLUP) to 0.46 for MY (BLUP), bias ranged from -0.62 for MY (ssGBLUP) to 0.0002 for AFC (BLUP/truncated), and dispersion ranged from 0.88 for MY (BLUP/ A_UPG) to 1.13 for LL (BLUP). Genetic trend showed genetic gains for all traits across 20 years of selection and the impact of including either genomic information, UPG or pedigree truncation under GEBV accuracies ranged among the evaluated traits. Overall, methods using UPGs, truncation pedigree and genomic information exhibited potential to improve GEBV accuracies, bias and dispersion for all traits compared with other methods. Truncated scenarios promoted high genetic gains. In small populations with few genotyped animals, combining truncated pedigree or UPG with genomic information is a feasible approach to deal with missing pedigrees.
RESUMEN
O objetivo deste estudo foi avaliar o efeito da suplementação durante diferentes períodos gestacionais sobre a produção de lã de ovelhas e cordeiros da raça Ideal. Foram utilizadas 53 ovelhas da raça Ideal, com escore corporal médio (3), inseminadas pela técnica de laparoscopia, com sêmen fresco de um único reprodutor; e seus cordeiros. Os tratamentos experimentais foram: sem suplementação (n=9); suplementação do início da gestação até 50 dias (n=11); suplementação dos 51 aos 100 dias de gestação (n=11); suplementação dos 101 aos 150 dias - final da gestação (n=11); e suplementação durante toda a gestação (n=11). A suplementação foi a 1,5% do peso corporal. Amostras de lã das ovelhas e dos cordeiros foram tomadas na região do costilhar esquerdo e enviadas ao laboratório para análises objetivas de finura de lã. As suplementações no terço final e durante toda a gestação proporcionavam os melhores resultados, com aumento de produção de lã e de peso das ovelhas. Ovelhas que receberam suplementação durante toda a gestação apresentaram maior diâmetro de fibra e peso corporal. O desempenho de lã dos cordeiros não foi influenciado pela alimentação de ovelhas durante a gestação.(AU)
The objective of this study was to evaluate the effect of supplementation during different gestational periods on the wool production of sheep and lambs of the Ideal breed. Fifty-three adult Ideal sheep were used, with a mean body score inseminated by the laparoscopy technique using fresh sperm from a single breeder and his lambs. Treatment groups: No supplementation (n=9); Supplementation in the beginning of gestation up to 50 days (n=11); Supplementation from 51 to 100 days of gestation (n=11); Supplementation from 101 to 150 days - end of gestation (n=11) ;and Supplementation throughout the gestation (n=11). The supplementation was at 1.5% of body weight. After birth, lambs were kept with their mothers in cultivated pasture of black oats and ryegrass. Wool samples from sheep and lambs were taken in the left-hand region and sent to the laboratory for objective analyzes of wool fineness. The supplementation performed in the final third and throughout the gestation provides the best results, with increased sheep weight. Ewes that received supplementation throughout pregnancy had greater fiber diameter and body weight. The wool performance of lambs was not influenced by feeding sheep during gestation.(AU)
