Test Interval Method of Calculating Dairy Herd Improvement Association Records

Sargent, Frederick; Lytton, V.H.; Wall, O.G.

doi:10.3168/jds.s0022-0302(68)86943-7

Cited by 66 publications

(43 citation statements)

References 2 publications

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“…Cows in this study with dry periods between 21 With smaller subclass sample sizes, some variation in the magnitude of these differences is, of course, expected but the direction of difference has generally been consistent.…”

Section: Comparison Of Results To Previously Published Researchmentioning

confidence: 57%

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Minimum days dry to maximize milk yield in subsequent lactation

2005

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-The objective of this research was to determine the effect of days dry (DD) on actual milk yield and to identify the minimum dry period length needed to maximize milk yield in the subsequent lactation. Field data collected through the U.S. dairy herd improvement association from January, 1997 to December, 2003 and extracted from the Animal Improvement Programs Laboratory national database were used for analysis. Actual lactation records calculated from test-day yields using the test-interval method were used in this study. The model for analysis included herd-year of calving, year-state-month of calving, previous lactation milk yield, age at calving, and DD as a categorical variable. Interactions were added to this model to determine if the effects of DD on subsequent lactation milk yield depended on previous lactation milk yield, age at calving, somatic cell score, or days open. Milk yield in the subsequent lactations was generally maximized with a 60 to 65 d dry period, regardless of parity. Days dry effects on milk yield were, for the most part, consistent across lactations, although dry periods < 35 d are somewhat more detrimental to milk yield after first lactation than after second and later lactations. Dry periods less than 20 d result in very pronounced losses in subsequent lactation yield. A short dry period (< 40 d) for high producing cows that bred back early in lactation proved to be the worst combination in terms of maximizing subsequent lactation milk yield. days dry / lactational milk yield Résumé -Période de tarissement minimale pour maximiser la production laitière pendant la lactation suivante. L'objectif de cette recherche a été de déterminer les effets de la durée de la période de tarissement (PT) sur la production totale de lait pendant la lactation suivant le tarissement, et d'identifier la période minimale nécessaire pour maximiser cette production. Les données utilisées dans cette étude ont été collectées auprès d'associations d'éleveurs laitiers d'Amérique du Nord entre janvier 1997 et décembre 2003, et extraites de la base nationale de l'Animal Improvement Programs Laboratory. La production laitière totale, calculée à partir des productions mensuelles, a été utilisée dans cette étude. Le modèle d'analyse contenait les effets du troupeau-année de vêlage, de l'âge au vêlage, et de la durée de la PT. Des interactions furent ajoutées au modèle pour déterminer si les effets de la PT sur la production après tarissement dépendaient de la production avant tarissement, de l'âge au vêlage, du score de cellules somatiques et de l'intervalle vêlage-insémination fécondante. La production de lait après tarissement a généralement été maximale pour une PT de 60 à 65 jours, quelle que soit la parité. Les effets de la durée de la PT sur la production laitière ont généralement été constants quelle que soit la parité, mais de courtes PT après la première lactation ont été plus néfastes à la production laitière que de courtes PT après les lactations de parités supérieures. Des PT inférieures à 20 ...

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Section: Comparison Of Results To Previously Published Researchmentioning

confidence: 57%

“…If short subsequent lactations are unrelated to DD, then they will occur randomly across dry periods and cause no bias in the analyses. Thus, actual milk yield was used in this study and was calculated from test-day yields using the test-interval method [21] and the adjustment factors of Shook et al [23].…”

Section: Datamentioning

confidence: 99%

Minimum days dry to maximize milk yield in subsequent lactation

2005

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“…Testday records in different intervals are treated as different traits (Meyer et al, 1989, Pander et al, 1992, Pander et al, 1993, Swalve, 1995. The method is known as test interval method (TIM) and was described 40 years ago by Everett and Carter (1968) and Sargent et al (1968). This kind of modelling is frequently used in dairy cows (Meyer et al, 1989, Pander et al, 1992, Swalve, 1995, Schaeffer and Jamrozik, 1996, Schaeffer, 1998 and seldom in dairy sheep (Baro et al, 1994, Serrano et al, 2001.…”

Section: Introductionmentioning

confidence: 99%

Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

Komprej¹,

Kompan²,

Kovač³

2011

Acta Agriculturae Slovenica

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“…Total milk yield was the lactation milk yield calculated from the original test-day records using the test-interval method of Sargent et al (1968).…”

Section: Curve Parametersmentioning

confidence: 99%

Environmental factors affecting lactation curve parameters in the United Kingdoms commercial dairy herds

Portillo¹,

Pollott

2011

Arch. med. vet.

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Environmental factors affecting lactation curve parameters in the United Kingdom's commercial dairy herdsFactores ambientales que determinan los parámetros de la curva de lactación usando un modelo biológico en rebaños lecheros comerciales en el Reino Unido RESUMENEl objetivo del trabajo fue determinar los factores ambientales que determinan los parámetros de la curva de lactación utilizando un modelo biológico de ajuste de curva. El modelo propuesto ajusta dos curvas logísticas que simulan el incremento inicial en el número de células secretoras de leche en la lactación temprana, y la progresión de la apoptosis en la lactación tardía. Se analizaron lactaciones de 182.987 vacas Holstein-Friesian. Los factores vaca, rebaño y número de lactación explican el 74% de la suma total de cuadrados (P < 0,001). La edad promedio a primer parto fue de 28 meses, teniendo un efecto significativo sobre la mayoría de los parámetros de la curva. Incrementos en la edad a primer de parto (20-40 meses) fueron asociados con incrementos lineales en los rendimientos totales de leche. Los parámetros tasa máxima de secreción y máximo de lactación estuvieron altamente correlacionados entre sí, indicando que son virtualmente los mismos. Adicionalmente, altos valores de estos dos parámetros indican altos rendimientos totales de leche. El día del máximo de lactación se correlacionó negativamente (0,64) con persistencia de la lactación. Los factores vaca, rebaño número de lactación y edad a primer parto fueron los factores más determinantes sobre los parámetros de la curva de lactación de vacas de primera lactancia así como de lactaciones múltiples.

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Test Interval Method of Calculating Dairy Herd Improvement Association Records

Cited by 66 publications

References 2 publications

Minimum days dry to maximize milk yield in subsequent lactation

Minimum days dry to maximize milk yield in subsequent lactation

Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

Environmental factors affecting lactation curve parameters in the United Kingdoms commercial dairy herds

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Test Interval Method of Calculating Dairy Herd Improvement Association Records

Cited by 66 publications

References 2 publications

Minimum days dry to maximize milk yield in subsequent lactation

Minimum days dry to maximize milk yield in subsequent lactation

Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

Environmental factors affecting lactation curve parameters in the United Kingdoms commercial dairy herds

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Product

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Environmental factors affecting lactation curve parameters in the United Kingdoms commercial dairy herds