Three Methods to Validate the Estimation of Genetic Trend for Dairy Cattle

Boichard, Didier; Bonaı̈ti, B.; Barbat, Anne; Mattalia, Sophie

doi:10.3168/jds.s0022-0302(95)76652-8

Cited by 59 publications

(62 citation statements)

References 9 publications

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“…Interbull trend validation methods were used to verify that estimates of genetic trend based on traditional PBV were accurate, and that breeding values were not overestimated (50). The first test compares the genetic trend in official evaluations that include data from multiple lactations with evaluations that include only first lactation data, and estimates of genetic trend should be similar for both.…”

Section: Methodsmentioning

confidence: 99%

Changes in genetic selection differentials and generation intervals in US Holstein dairy cattle as a result of genomic selection

García-Ruiz

Cole

VanRaden

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

464

360

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Seven years after the introduction of genomic selection in the United States, it is now possible to evaluate the impact of this technology on the population. Selection differential(s) (SD) and generation interval(s) (GI) were characterized in a four-path selection model that included sire(s) of bulls (SB), sire(s) of cows (SC), dam(s) of bulls (DB), and dam(s) of cows (DC). Changes in SD over time were estimated for milk, fat, and protein yield; somatic cell score (SCS); productive life (PL); and daughter pregnancy rate (DPR) for the Holstein breed. In the period following implementation of genomic selection, dramatic reductions were seen in GI, especially the SB and SC paths. The SB GI reduced from ∼7 y to less than 2.5 y, and the DB GI fell from about 4 y to nearly 2.5 y. SD were relatively stable for yield traits, although modest gains were noted in recent years. The most dramatic response to genomic selection was observed for the lowly heritable traits DPR, PL, and SCS. Genetic trends changed from close to zero to large and favorable, resulting in rapid genetic improvement in fertility, lifespan, and health in a breed where these traits eroded over time. These results clearly demonstrate the positive impact of genomic selection in US dairy cattle, even though this technology has only been in use for a short time. Based on the four-path selection model, rates of genetic gain per year increased from ∼50–100% for yield traits and from threefold to fourfold for lowly heritable traits.

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Section: Methodsmentioning

confidence: 99%

Changes in genetic selection differentials and generation intervals in US Holstein dairy cattle as a result of genomic selection

García-Ruiz

Cole

VanRaden

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

464

360

View full text Add to dashboard Cite

show abstract

Section: Methodsmentioning

confidence: 99%

“…Boichard et al (1995) has proposed three methods to validate the models used for genetic evaluation of dairy cattle. Genetic trend estimation in the current study was investigated through a residual analysis (Boichard et al, 1995). The method uses 'within bull variation of Daughter Yield Deviations' or DYD values (VanRaden & Wiggans, 1991;Boichard et al, 1995).…”

Section: Methodsmentioning

confidence: 99%

“…Genetic trend estimation in the current study was investigated through a residual analysis (Boichard et al, 1995). The method uses 'within bull variation of Daughter Yield Deviations' or DYD values (VanRaden & Wiggans, 1991;Boichard et al, 1995). The DYD analysis is quite general and can be used to detect problems in the model of analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, Daughter Yield Deviations of bulls are average performances of the bulls' daughters adjusted for the dam breeding value and for all the effects included in the model, except daughter breeding values (Boichard et al, 1995). Expected DYD values should only depend on the bull and are theoretically independent of any environmental effect, particularly the birth year of the daughters.…”

Section: Methodsmentioning

confidence: 99%

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The effect of phantom parent groups on genetic trend estimation

Theron¹,

Kanfer²,

Rautenbach³

2002

SA J. An. Sci.

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In an animal model evaluation of breeding values it is assumed that the base animals are all at the same genetic level. However, in the South African Holstein population, animals of different genetic levels were imported from foreign countries, thus causing a deviation from this assumption. The effect of this deviation is considered using first lactation records from 393 458 Holstein cows. Genetic trend estimation is studied through a time trend analysis of within-Bull-yearly-Daughter Yield Deviations, or DYD's. Bias in the estimation of trend was reduced when phantom parent groups were taken into account. The 109 385 base animals were replaced by 64 phantom parent groups. Phantom parent groups were constructed by combining year of birth, country of birth and selection intensity of the phantom parents. In recent years, foreign sires have been more affected by the exclusion of phantom parents groups in the model, than local sires, although ranking coefficients for the 15 771 sires in the analysis were in excess of 90%. Ranking coefficients for cows were also high.

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Practical application of daughter yield deviations in dairy cattle breeding

Szyda

Ptak

Komisarek³

et al. 2008

J Appl Genet

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Daughter yield deviations (DYDs) of bulls and yield deviations (YDs) of cows, besides estimated breeding values (EBVs), are standard measures of animals' genetic merits in routine genetic evaluations worldwide. In this contribution, we first point out differences and similarities between DYDs and EBVs calculated for milk, fat and protein yields. While the latter measure represents the additive polygenic value of an animal, the former consists of both the additive polygenic and residual components. Then, a summary of DYDs and YDs calculated for the Polish population of dairy cattle is presented. The estimated correlations between DYDs and EBVs are generally high, but vary considerably depending on the minimum number of daughters used for calculation of DYDs and on the accuracy of calculated DYDs. Using DYDs estimated for each production year for 16 452 bulls, we demonstrate how to use DYDs for the validation of genetic trend estimated in the model used for genetic evaluation. Based on genotypic data of 252 bulls, we show that DYDs can be used for the estimation of candidate gene effects. For each of the yield traits, the within-bull genetic trend was relatively high, ranging between 1.39% of genetic standard deviation per production year for milk and 7.67% of genetic standard deviation per production year for fat, both in the 2nd lactation. Out of 8 polymorphisms tested, 5 showed a significant correlation with DYD, with the highest effect attributed to the polymorphism within the leptin receptor gene, whose additive effect was estimated as 247.33 kg of milk at 2nd parity.

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Three Methods to Validate the Estimation of Genetic Trend for Dairy Cattle

Cited by 59 publications

References 9 publications

Changes in genetic selection differentials and generation intervals in US Holstein dairy cattle as a result of genomic selection

Changes in genetic selection differentials and generation intervals in US Holstein dairy cattle as a result of genomic selection

The effect of phantom parent groups on genetic trend estimation

Practical application of daughter yield deviations in dairy cattle breeding

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