|Technical Guide for SMEs in the Dairy Industry (CDI, 1999, 74 p.)|
|PART 1 - DAIRY FARMING|
|CHAPTER II: REPRODUCTION OF CATTLE|
The indigenous breeds reach puberty at 26 months on average, whereas it takes only 10 to 11 months for the exotic breeds. The variation factor is the feed, although a female is considered to have reached puberty when its weight is 2/3 of the weight of the adult.
The age at which cows first calve is 3 years 9 months for local breeds and 24 months for exotic breeds. The interval between calvings, an important factor in fertility and productivity, is 473 days for local breeds and 360 days for exotic breeds. This interval depends on several factors, namely:
- Return to heat: this takes an average of 45 days for milk cows, and 60 to 90 days for suckler cows;
- Average number of inseminations per impregnation: 1.25 for heifers and 2.24 for cows;
- Interval between calving and first insemination: 56 days ± 28.
Consequently, these are factors that depend on farming practice and herd maintenance, and therefore the post-calving period.