Reproductive physiology

Detailed description of follicular dynamic and oestrus cycle in bos indicus can be found in Bo et al., (2003) and Sartorelli et al. (2005). The main reproduction traits are identical in bos indicus and bos Taurus, there are however some differences that should be considered in the reproduction management.

Differences in reproduction traits between Bos Taurus and Bos indicus cattle

	Bos taurus	Bos indicus
Maximum diameter of the dominant follicle	14–20mm	10–12 mm
Average corpus luteum diameter	20–30 mm	17–21 mm
Age at puberty	Approx. 12-14 months	16-40 months
Oestrus duration	Approx. 18 h mainly during the day	Approx. 11 h Mainly at night
Ovulation	28-31 h after the onset of heat	25-26h after the onset of heat
Hierarchy	Can affect the oestrus behaviour	Strongly influences oestrus behaviour

Practical implications of differences in reproductive physiology between bos indicus and bos taurus

• In bos indicus CL is more difficult to palpate during the rectal examination
• Bos indicus females are highly sensitive to the FSH dosages currently used for superstimulation of bos taurus cattle and lower doses should be used in this species.
  
• Due to high incidence of post partum anoestrus and poor body condition in the first months post partum the answer in many oestrus synchronisation programs is poor in pastured bos indicus cows in the first 100d pp.
• Improvement of the nutrition of bos indicus cows and temporary calf removal are important tools when an oestrus synchronisation program is to be used in bos indicus suckled cows.