| Summary: | The purpose of the study was to evaluate the influence
of the environmental factors on calving interval
of Blanco Orejinegro cattle. The study was conducted
in a mountainous zone, of intermediate
temperature, in the north central part of Colombia.
The adjusted average calving interval of 320 observations
was 454.1 days and the date of conception
averaged about 5.5 months after the date of parturition.
Analysis of variance demostrated that effects
asociated with location in the Experimental farm and
age of dam were statistically significant at 1 and 5%
level of probability, respectively. Season of calving
approached significance. The other sources of variation
(year of calving, sex of calf and interaction of year
and season) did not show significance.
Cows calving in the higher part of the farm (1.200
metres) had calving intervals 31 days larger than cows
calving in the lower part (800 metres). Cows of less
than 3 years had the largest calving interval and cows
of 7 to 8 years of age had the shortest calving interval.
The difference between the two groups was 69.5 days.
In general, old cows had shorter intervals than young
cows. The best season of calving in relation with
fertility of cows was from January to March, the
driest season of the year. The correlation of rainfall
during season of calving with interval to the next
parturition was 0.659 (P ( .01).
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