Pre-pubertal measurements of the somatotrophic axis as predictors of milk production in Holstein-Friesian dairy cows.
Domest Anim Endocrinol
; 31(1): 1-18, 2006 Jul.
Article
em En
| MEDLINE
| ID: mdl-16219444
ABSTRACT
This study investigated possible relationships between measurements of the somatotrophic axis in pre-pubertal dairy calves and subsequent milk yields. Endogenous growth hormone (GH) release was measured through a fed and fasted period in fifty 6-month-old Holstein-Friesian heifers and they were then challenged with growth hormone-releasing factor (GRF) to assess their GH release pattern. Insulin-like growth factor-I (IGF-I), insulin and glucose concentrations were measured in relation to time of feeding. Cows were subsequently monitored through their first three lactations to record peak and 305-day milk yields. In the first lactation, milk energy output for the first 120 days of lactation was also calculated. The mean 305-day milk yield increased from 7417 +/- 191 kg in the first lactation (n=37) to 8749 +/- 252 kg in the third (n=25). There were no significant relationships between any measures of GH secretion and peak or 305-day yield in any lactation. A highly significant positive relationship was established between the GH peak measured 10 min post-GRF challenge and 120-day milk energy values in the first lactation. This relationship was, however, only present in the sub-population of 12 cows culled after one or two lactations and was absent in the 25 animals remaining for the third lactation. There were no significant relationships between pre-pubertal IGF-I and fed or fasted insulin or glucose concentrations and any subsequent measurement of yield. The usefulness of GH secretagogue challenges in calves as a predictive test for future milk production is thus limited but may have some bearing on nutrient partitioning and longevity.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fator de Crescimento Insulin-Like I
/
Bovinos
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Hormônio do Crescimento
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Leite
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
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Risk_factors_studies
Limite:
Animals
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Pregnancy
Idioma:
En
Revista:
Domest Anim Endocrinol
Assunto da revista:
ENDOCRINOLOGIA
/
MEDICINA VETERINARIA
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Reino Unido
País de publicação:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA