Oestrus management

Because of high incidence of post partum anoestrus and relatively short breeding period adopted in beef production treatment protocols to be used in bos indicus herds should be capable of inducing oestrus and ovulation in anoestrus animals.

Review of the main approaches can be found in Bo et al. (2003) and Baruselli et al (2004).

Prostaglandins

Incidence of cyclicity in the early post calving period is much lower in cattle of bos indicus origin maintained on pasture than in bos taurus breeds.

Prostaglandins are not an ideal choice for management of oestrus in bos indicus herds.

Are prostaglandins less efficient in bos indicus cows?

Ovsynch protocol and modifications

Classical Ovsynch protocol can be applied in bos indicus cows with a success rate comparable to the results obtained in bos taurus cows in comparable cyclicity status.

Cows
Pregnancy rates after fixed time AI in oestrus induced with Ovsynch protocol do not differ from those reported for bos taurus, ranging between 42 and 48% Pregnancy rates in anoestrus cows are usually lower (15%) than in cycling cows (45%) as it is also observed in standard beef breeds.

Heifers
Pregnancy rates in bos indicus heifers similarly to the situation observed in bos taurus breeds, are more variable and oscillate between 21 and 43%. This is thought to be attributable to the low incidence of ovulation of the dominant follicle after the first GnRH which results in poor synchronisation of oestrus after the second GnRH.

Progestagens

Systems including progestagens are considered as the method of choice in the management of oestrus in bos indicus cows, especially managed on pasture.

Advantage of progestargen/progesterone based systems such as Crestar:
  • the induction of fertile oestrus
  • provision of so called progesterone priming, that reduces the incidence of short luteal phase after induced ovulation, which reduces early pregnancy losses and improves cumulative pregnancy rates

Crucial issues
Use of PMSG with progestagens An important tool used to increase pregnancy rates in FTAI programs in bos indicus cattle in anoestrus.

Because of the higher sensitivity of bos indicus breeds to gonadotrophins a dose in the range of 300-500 IU of eCG/PMSG (Folligon) should be given at the time of removal of the progestagen source.

Combination of progestagen treatment and calf management Temporary removal of suckling calf markedly improves the efficacy of oestrus induction and synchronisation systems. Calves are usually separated from cows at 48h before the withdrawal of the source of progestagen until the AI is done.

The decision about including this tool in the breeding management of the herd should be always balanced on the basis of the benefits coming from increased pregnancy rates and shorter breeding period against possible losses in daily gains in calves due to the tress and change in nutrition.

Read about the use of Crestar in bos indicus heifers.

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