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Titolo:
EFFECT OF DISEASES ON THE CULLING OF HOLSTEIN DAIRY-COWS IN NEW-YORK-STATE
Autore:
GROHN YT; EICKER SW; DUCROCQ V; HERTL JA;
Indirizzi:
CORNELL UNIV,COLL VET MED,DEPT CLIN SCI,EPIDEMIOL SECT ITHACA NY 14853 INRA,GENET QUANTITAT & APPL STN F-78352 JOUY EN JOSAS FRANCE
Titolo Testata:
Journal of dairy science
fascicolo: 4, volume: 81, anno: 1998,
pagine: 966 - 978
SICI:
0022-0302(1998)81:4<966:EODOTC>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
FINNISH AYRSHIRE CATTLE; REPLACEMENT POLICIES; FRIESIAN COWS; MILK-YIELD; ASSOCIATION; PERFORMANCE; DISORDERS; LIFE;
Keywords:
TIME-DEPENDENT COVARIATES; SURVIVAL ANALYSIS; DISEASE; CULLING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
21
Recensione:
Indirizzi per estratti:
Citazione:
Y.T. Grohn et al., "EFFECT OF DISEASES ON THE CULLING OF HOLSTEIN DAIRY-COWS IN NEW-YORK-STATE", Journal of dairy science, 81(4), 1998, pp. 966-978

Abstract

The effect of seven diseases on culling was measured in 7523 Holsteincows in New York State. The cows were from 14 herds and had calved between January 1, 1994 and December 31, 1994; all cows were followed until September 30, 1995. Survival analysis was performed using the Cox proportional hazards model to incorporate time-dependent covariates for diseases. Different intervals representing stages of lactation were considered for effects of the diseases. Five models were fitted to test how milk yield and conception status modified the effect of diseaseson culling. Covariates in the models included parity, calving season,and time-dependent covariates measuring diseases, milk yield of the current lactation, and conception status. Data were stratified by herd. The seven diseases and lactational risks under consideration were milk fever (0.9%), retained placenta (9.5%), displaced abomasum (5.3%), ketosis (5.0%), metritis (4.2%), ovarian cysts (10.6%), and mastitis (14.5%). Older cows were at a much higher risk of being culled. Calving season had no effect on culling. Higher milk yield was protective against culling. Once a cow had conceived again, her risk of culling dropped sharply. In all models, mastitis was an important risk factor throughout lactation. Milk fever, retained placenta, displaced abomasum, ketosis, and ovarian cysts also significantly affected culling at different stages of lactation. Metritis had no effect on culling. The magnitude of the effects of the diseases decreased, but remained important, when milk yield and conception status were included as covariates. These results indicated that diseases have an important impact on the actual decision to cull and the timing of culling. Parity, milk yield, and conception status are also important factors in culling decisions.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 22:29:56