Reliability of breeding values between random regression and 305-day lactation models

Abstract

-The objective of this work was to verify the gain in reliability of estimated breeding values (EBVs), when random regression models are applied instead of conventional 305-day lactation models, using fat and protein yield records of Brazilian Holstein cattle for future genetic evaluations. Data set contained 262,426 test-day fat and protein yield records, and 30,228 fat and protein lactation records at 305 days from first lactation. Single trait random regression models using Legendre polynomials and single trait lactation models were applied. Heritability for 305-day yield from lactation models was 0.24 (fat) and 0.17 (protein), and from random regression models was 0.20 (fat) and 0.21 (protein). Spearman correlations of EBVs, between lactation models and random regression models, for 305-day yield, ranged from 0.86 to 0.97 and 0.86 to 0.98 (bulls), and from 0.80 to 0.89 and 0.81 to 0.86 (cows), for fat and protein, respectively. Average increase in reliability of EBVs for 305-day yield of bulls ranged from 2 to 16% (fat) and from 4 to 26% (protein), and average reliability of cows ranged from 24 to 38% (fat and protein), which is higher than in the lactation models. Random regression models using Legendre polynomials will improve genetic evaluations of Brazilian Holstein cattle due to the reliability increase of EBVs, in comparison with 305-day lactation models.Index terms: breeding value, correlation, Legendre polynomials, reliability. Confiabilidade de valores genéticos entre modelos de regressão aleatória e de lactação aos 305 diasResumo -O objetivo deste trabalho foi verificar o ganho em confiabilidade dos valores genéticos estimados (VGE), quando os modelos de regressão aleatória são aplicados em lugar dos modelos convencionais de lactação até os 305 dias, tendo-se utilizado registros de produção de gordura e proteína de bovinos da raça Holandesa no Brasil, para futuras avaliações genéticas. O conjunto de dados continha 262.426 registros de produção de gordura e proteína no dia do controle e 30.228 registros de produção acumulada de gordura e proteína até os 305 dias de lactação. Aplicaram-se modelos de regressão aleatória unicaracterística, com os polinômios de Legendre, e modelos unicaracterística de lactação aos 305 dias. A herdabilidade estimada para as produções até os 305 dias pelos modelos de lactação foi 0,24 (gordura) e 0,17 (proteína), e, pelos modelos de regressão aleatória, foi 0,20 (gordura) e 0,21 (proteína). Correlações de Spearman dos VGEs entre os modelos de lactação e de regressão aleatória, para a produção aos 305 dias, variaram de 0,86 a 0,97 e 0,86 a 0,98 (touros) e de 0,80 a 0,89 e 0,81 a 0,86 (vacas), quanto à gordura e à proteína, respectivamente. O aumento médio em confiabilidade dos VGEs para a produção aos 305 dias variou de 2 a 16% (gordura) e de 4 a 26% (proteína), em touros, e variou de 24 a 38% (gordura e proteína) em vacas, o que é superior àquela obtida pelos modelos de lactação. Os modelos de regressão aleatória com uso dos polinômios de Legendre melhorarão a av...

Random regression test‐day models to describe milk production and fatty acid traits in first lactation Walloon Holstein cows

“…The tendency towards an increase in heritability over days for milk production traits is in agreement with the results of Bastin et al (2011), Bormann et al (2003, Druet et al (2005), Kheirabadi (2019) and Soyeurt et al (2008). Fat and protein contents were more heritable (h 2 maximum values of 0.54 and 0.58, respectively) with similar trajectories to the findings of Padilha et al (2016). Thus, the high heritabilities indicate that genetic gains will be effective when these traits are used as selection criteria in breeding programmes of Walloon Holstein cows.…”

“…Fat and protein contents were more heritable ( h 2 maximum values of 0.54 and 0.58, respectively) with similar trajectories to the findings of Padilha et al. (2016). Thus, the high heritabilities indicate that genetic gains will be effective when these traits are used as selection criteria in breeding programmes of Walloon Holstein cows.…”

“…Evaluating fat and protein contents in Brazilian Holstein cattle, Padilha et al (2016) found a lower order for additive genetic and permanent environment effects. For the milk FA traits, Narayana et al (2017) reported that DIC values decreased with an increase in the degree of Legendre polynomials.…”

“…Evaluating fat and protein contents in Brazilian Holstein cattle, Padilha et al. (2016) found a lower order for additive genetic and permanent environment effects. For the milk FA traits, Narayana et al.…”

The role of fixed factors in the variability of milk yield in Irmeni cattle under industrial complex conditions

“…В настоящее время наиболее востребованными решениями являются линейные и нелинейные смешанные модели, лежащие в основе BLUP [13][14][15][16][17][18], включая байесовский подход [19,20] и модели GBLUP [21]. Применение таких инструментов показывает высокую эффективность в условиях малых и крупных промышленных комплексов [22].…”