Elsevier

Journal of Dairy Science

Volume 75, Issue 1, January 1992, Pages 288-293
Journal of Dairy Science

Article
Factors Affecting Days Open, Gestation Length, and Calving Interval in Florida Dairy Cattle1

https://doi.org/10.3168/jds.S0022-0302(92)77764-9Get rights and content
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Abstract

Effects of several factors on reproductive performance were evaluated. Mean performance and number of observations were for days from parturition to first service, 93 and 7730; days from first to successful service, 35 and 11,751; days open, 123 and 8571; gestation length, 280 and 13,612; and calving interval, 400 and 8524. Data covered 52 yr during which no detectable trends in calving interval occurred; other variables changed slightly. Jerseys had 8 fewer d from parturition to first service, 16 fewer d from first service to conception, 8 fewer d open, and 8-d shorter calving intervals than did Guernseys and Holsteins, which did not differ. Cows freshening in warm rather than cool weather suffered by 7, 7, 12, and 13 d for these variables. Repeatabilities ranged from .05 to .12; heritabilities were .05 and .06. Nonmaternal estimate of heritability of gestation length was .22. Phenotypic and genetic correlations between days from parturition to first service and calving interval were .48 and .87; for days open and calving interval, they were .97 and .96. Although days from first to successful service were essentially uncorrelated with days open and calving interval phenotypically (.05), genetic correlations were greater than 1.0 and estimated as unity. Results show no discrepancy between estimates for measures of reproductive performance in a subtropical environment and numerous studies in temperate areas. Large studies from subtropical areas are sparse; essentially none concerns long-term trends.

Key words

Florida
subtropical
reproduction

Cited by (0)

1

Florida Agricultural Experiment Station Journal Series Number R-01613.

2

Escola de Veterinaria da UFMG, 3000-BeIo Horizonte, Brazil.

4

Deceased.

5

Department of Animal and Range Science, North Dakota State University, Fargo 58105-5727.