Factores del animal y el manejo predestete que afectan la edad al primer parto en hatos de lechería especializada de Costa Rica
2019
The age at first calving (AFC) correspond to one
of the most important parameters to quantify
the productive efficiency of bovines, because
it influences the productive performance
and milk composition. The aim of the study
was to quantify the effect of the animal and
environmental variables, modifiable and nonmodifiable, from birth to weaning, on AFC in
specialized dairy herds in Costa Rica. A cohort
retrospective study was conducted, including a
total of 2980 Jersey and Holstein cows with AFC
in the period between 2013 and 2015, belonging
to 22 specialized dairy herds located in different
ecological zones of Costa Rica, with data in the
Bovine VAMPP program. All data in the present
research, was analyzed by descriptive analysis and a generalized linear model. The average AFC
for the animals in the present study was 27.4
months (±4.7). Non- modifiable variables, like
breed, had significant effect over AFC, with 30,1
(CI95%: 29.8-30.4) and 28.4 months (CI 95%:
28.1-28.8) for Holstein and Jersey respectively.
Furthermore, the results showed a significant
effect of management as a modifiable variable
(p<0.0001) revealing that farms with high quality
calf rearing protocols had AFC of 27.63 months
(CI95%: 27.24-28.03), contrary to poor quality
systems (AFC: 30.20; CI95%: 29.83-30.57). This
tendency was consistent whether the management
variable was included as independent in the
model or associated to breed and herd factors,
where high efficiency in calf rearing reflects into
better values of AFC.
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