Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis

Baldassare Portolano, Valentina Riggio, Henk Bovenhuis, Van Arendonk, Maizon, Riggio

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Abstract

The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 103 cells/mL, were classified as 1 if mxSCC ≤ 500, 2 if 500 < mxSCC < 1,000, and 3 if mxSCC ≥ 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20% higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7% on the logarithmic scale and 11% on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19% of the variation on the logarithmic scale and 27% of the variation on the real scale.
Lingua originaleEnglish
pagine (da-a)6160-6166
Numero di pagine7
RivistaJournal of Dairy Science
Volume92
Stato di pubblicazionePublished - 2009

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dairy sheep
Survival Analysis
somatic cell count
Sheep
Cell Count
ewes
flocks
heritability
sheep
culling (animals)
Mastitis
technicians
somatic cells
Lactation
milking
mastitis
Milk
lactation
testing
farmers

All Science Journal Classification (ASJC) codes

  • Food Science
  • Genetics
  • Animal Science and Zoology

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title = "Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis",
abstract = "The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 103 cells/mL, were classified as 1 if mxSCC ≤ 500, 2 if 500 < mxSCC < 1,000, and 3 if mxSCC ≥ 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20{\%} higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7{\%} on the logarithmic scale and 11{\%} on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19{\%} of the variation on the logarithmic scale and 27{\%} of the variation on the real scale.",
author = "Baldassare Portolano and Valentina Riggio and Henk Bovenhuis and {Van Arendonk} and Maizon and Riggio",
year = "2009",
language = "English",
volume = "92",
pages = "6160--6166",
journal = "Journal of Dairy Science",
issn = "0022-0302",
publisher = "Elsevier Limited",

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TY - JOUR

T1 - Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis

AU - Portolano, Baldassare

AU - Riggio, Valentina

AU - Bovenhuis, Henk

AU - Van Arendonk, null

AU - Maizon, null

AU - Riggio, null

PY - 2009

Y1 - 2009

N2 - The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 103 cells/mL, were classified as 1 if mxSCC ≤ 500, 2 if 500 < mxSCC < 1,000, and 3 if mxSCC ≥ 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20% higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7% on the logarithmic scale and 11% on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19% of the variation on the logarithmic scale and 27% of the variation on the real scale.

AB - The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 103 cells/mL, were classified as 1 if mxSCC ≤ 500, 2 if 500 < mxSCC < 1,000, and 3 if mxSCC ≥ 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20% higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7% on the logarithmic scale and 11% on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19% of the variation on the logarithmic scale and 27% of the variation on the real scale.

UR - http://hdl.handle.net/10447/42371

M3 - Article

VL - 92

SP - 6160

EP - 6166

JO - Journal of Dairy Science

JF - Journal of Dairy Science

SN - 0022-0302

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