Repeatability of Type Ratings in Dairy Cattle

Johnson, Leslie E.; Lush, Jay L.

doi:10.3168/jds.s0022-0302(42)95266-4

Cited by 16 publications

(5 citation statements)

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“…The heritability for dairy character-14 was .21, near the average of a number of estimates from .03 to .34 from other studies (1,6,10,11,13,18,21,23,27). The estimates for the remaining body traits were less than .20 and do not appear to differ from previous findings.…”

Section: Resultssupporting

confidence: 50%

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Type Appraisal: II. Variation in Type Traits Due to Sires, Herds, and Years

Norman

Vleck

1972

Journal of Dairy Science

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Variance components were estimated from type appraisal data to determine the importance of year, herd, sire, and herd x sire effects uport 49 body, udder, and management traits. Estimates were based on over 16,000 appraisals on daughters of Holstein artil~cial insemination sires. The variation explained by these effects never exceeded 34g of the total variance. Year effects were almost nonexistent (--2 to 3g). Herd effects were small for all traits except feeding speed, body weight, intensity and persistency of edema, and ketosis, and never exceeded 25g.Most appraisal traits had low heritabilities. The estimate for milking speed was .23 while estimates for other management traits were less than .08. The estimates for body weight and upstandingness were .40 and .39. Other body traits having estimates from .16 to .21 were sharpness, height of thurls, depth of body, levelness of rump, tightness of shoulders, and height of tail setting. The heritability estimates for udder traits were low. Estimates for only three of 21 udder traits exceeded .14. These were strength of rear attachment, rear teat spacing, and depth of udder.

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Section: Resultssupporting

confidence: 50%

“…McGilliard and Lush (16) noted that disagreement in ideals between experienced judges was small, so real changes in appearance were important causes of imperfect repeatability. Johnson and Lush (11) found that consecutive ratings, when cows were classifted at yearly intervals, appeared to be no more repeatable than nonconsecutive ratings.…”

Section: Introductionmentioning

confidence: 99%

Type Appraisal: II. Variation in Type Traits Due to Sires, Herds, and Years

Norman

Vleck

1972

Journal of Dairy Science

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“…The stability of conformation classification and the repeatability of the measurement were questioned in early studies (Johnson and Lush, 1942;Hyatt and Tyler, 1948). For example, Johnson and Lush (1942) reported high variation between evaluators and low repeatability for conformation traits ranging from 0.34 to 0.55. The heritability estimates reported for conformation traits were moderate to low.…”

Section: Conformationmentioning

confidence: 99%

A 100-Year Review: Identification and genetic selection of economically important traits in dairy cattle

Miglior

Fleming

Malchiodi

et al. 2017

Journal of Dairy Science

327

259

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Over the past 100 yr, the range of traits considered for genetic selection in dairy cattle populations has progressed to meet the demands of both industry and society. At the turn of the 20th century, dairy farmers were interested in increasing milk production; however, a systematic strategy for selection was not available. Organized milk performance recording took shape, followed quickly by conformation scoring. Methodological advances in both genetic theory and statistics around the middle of the century, together with technological innovations in computing, paved the way for powerful multitrait analyses. As more sophisticated analytical techniques for traits were developed and incorporated into selection programs, production began to increase rapidly, and the wheels of genetic progress began to turn. By the end of the century, the focus of selection had moved away from being purely production oriented toward a more balanced breeding goal. This shift occurred partly due to increasing health and fertility issues and partly due to societal pressure and welfare concerns. Traits encompassing longevity, fertility, calving, health, and workability have now been integrated into selection indices. Current research focuses on fitness, health, welfare, milk quality, and environmental sustainability, underlying the concentrated emphasis on a more comprehensive breeding goal. In the future, on-farm sensors, data loggers, precision measurement techniques, and other technological aids will provide even more data for use in selection, and the difficulty will lie not in measuring phenotypes but rather in choosing which traits to select for.

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“…should.be the most accurate estimate of a cow's true type. Johnson and Lush (1942) and Hyatt and Tyler (1948) have reported that two or more type ratings are a more accurate guide to an individual's true type than is one rating. The cows either had calved or were about to calve when the spring classification was made, and the fall classif1cat1on was made after weaning, The cows were divided into four age groups, 1, 2, 3, and 4 years and older, based on their age at their first classification.…”

Section: Weights and Measures -Calvesmentioning

confidence: 99%

“…The heritability of type rating was estimated to be 0.28 by doubling the intra-sire regression of daughter on dam. Johnson and Lush (1942) reported on the correlations between type and production in a study involving229 Holstein-Freisan cows. The measure of type was the official breed association classification score.…”

Section: Chapter II Review Of Literaturementioning

confidence: 99%