Changes in USDA Sire Summary Procedures

An animal model with a REML algorithm was used to estimate variances of additive genetic effects and interaction effects of sire and herd. Milk and fat yields were analyzed for fmt, second, and thrd lactations of Holsteins from California, New York, and Pennsylvania. Twenty samples of data were used in the study: 10 from California, 4 from New York, and 6 from Pennsylvania. Abbreviation key: c2 = fraction of variance that was due to sire and herd interaction effects, CA = California records, NYP = New York and Pennsylvania records.

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“…Differences between estimates for milk and fat yield in other studies (20,28,29,31,43) were only about .02, as in this study.…”

Section: Resultssupporting

confidence: 61%

“…Similarity among progeny in the same environment may be due to management (22,28). Then, the genetic correlations among expressions of the same genotype in different environments (1 1, 1995 35,47) are less than unity.…”

Section: Introductionmentioning

confidence: 99%

Variance of Interaction Effects of Sire and Herd for Yield Traits of Holsteins in California, New York, and Pennsylvania with an Animal Model

Dimov¹,

Albuquerque²,

Keown³

et al. 1995

Journal of Dairy Science

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“…These estimates agreed generally with estimates for sire models but were much less than the 14% used by USDA for national evaluations of dairy cattle ( 12,16,25). The value of 14% is used to adjust for the environmental correlation among records of daughters in the same herd, which may result in extreme deviations that are not genetic.…”

Section: Introductionsupporting

confidence: 64%

“…Most applications have ignored these relationships, probably because the application has been to protect against similar treatment of paternal sisters in single or only a few herds. Estimates of c2 range from the 14% used by the Animal Improvement Programs Laboratory of the USDA to nearly 0 (1,2,8,12,14,15,18,19,22,23).…”

Section: Introductionmentioning

confidence: 99%

Effect of Variance of Interaction Effects of Sire and Herd on Selection for Milk and Fat Yield

Dimov¹,

Keown²,

Vleck³

et al. 1996

Journal of Dairy Science

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The animal model for genetic evaluations of dairy cattle by the USDA currently includes a term for interaction effects of sire and herd. The relative magnitude of the variance of that effect was established in the 1960s as 14% of the total variance, but recent research has shown that the proportion is 2% or less. This report compared EBV using either the 14% or the actual estimate from 20 samples of records from herds in California, New York, and Pennsylvania. From 6 to 22% of bulls or cows selected for milk and fat yields based on evaluation with 14% of the total variance would not be selected using the sample estimates, depending on selection intensity, region, and whether only first or up to three lactations were used in the evaluations. Nevertheless, the average EBV of the bulls and cows selected based on 14% of the total variance were only slightly less than for those selected on 2%. This pilot research suggests that further study of the national data be done to establish the appropriate proportion of variance from interaction effects of sire and herd to use with national evaluations. Kinds of evaluations of bulls and ages of cows and bulls should be considered.( K e y words: selection, breeding values, variance of interaction)Abbreviation key: c2 = proportion of variance from interaction effects of sire and herd, CA = California herds, NYP = New York and Pennsylvania herds.

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“…Although considerable uneasiness has been expressed about non-AI evaluations, some of the truly outstanding bulls were discovered through non-AI sampling. Environmental correlation (interaction of herd and sire) has been considered for USDA genetic evaluations since the herdmate comparison (10). Accounting for environmental correlation was improved with the Modified Contemporary Comparison (MCC) (6, 7) and continues with the animal model (13).…”

Section: Introductionmentioning

confidence: 99%

Effect of Sampling Status and Adjustment for Heterogeneous Variance on Bias in Bull Evaluations

Powell

Wiggans

Norman

1994

Journal of Dairy Science

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Holstein bulls were assigned to sampling categories (AI stud, AI nonstud, or non-AI) based on bull code, controller number, and age at semen distribution. The AI stud bulls were sampled through traditional progeny-testing programs of 13 AI organizations; AI nonstud bulls had AI semen collection reported by another organization or by multiple organizations. The non-AI bulls had no reported AI semen collection. Actual daughter yield deviations for these three groups of bulls were compared with expected performance (parent average) to provide an indication of whether evaluations were free from bias for daughter yield deviations. Mean difference of daughter yield deviation from parent average was close to 0 kg for animal model evaluations of all 22,930 bulls but was positively biased by 46 kg of milk for AI nonstud bulls. Mean ETA and reliabilities for parents were highest for AI stud bulls and lowest for non-AI bulls. The AI stud bulls varied least and were intermediate for mean management, approximated as mean daughter yield minus bull ETA. Management was highest for AI nonstud bulls, which suggested that adjustment for heterogeneous variance might reduce bias. However, the effect of this adjustment on mean difference of daughter yield deviation from parent average was small.

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Changes in USDA Sire Summary Procedures

Cited by 34 publications

References 0 publications

Variance of Interaction Effects of Sire and Herd for Yield Traits of Holsteins in California, New York, and Pennsylvania with an Animal Model

Variance of Interaction Effects of Sire and Herd for Yield Traits of Holsteins in California, New York, and Pennsylvania with an Animal Model

Effect of Variance of Interaction Effects of Sire and Herd on Selection for Milk and Fat Yield

Effect of Sampling Status and Adjustment for Heterogeneous Variance on Bias in Bull Evaluations

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