(This is article 2 of 2 articles on this topic)
Although the foundation of a successful breeding season is laid earlier than 8 weeks before the start of the breeding season, this time can rightly be seen as the beginning of the 22 month cycle of “Conception to Consumption”, since it all starts with successful fertilization.
If things do not go smoothly here, it may result in cows not becoming pregnant in a fixed (90 days) breeding season, or that cows only become pregnant very late in the mating season. Eventually this leads to an extended inter calving period with concomitant economic loss, which can hardly be afforded!
The following areas require the necessary attention:
3.1 Modified “live” vaccines
Vaccination should not be done closer than 30 days before the start of the mating season. Furthermore, it is important to remember that the immune response of cows is not optimal during the first 30 days after calving.
It therefore only leaves us with one month to vaccinate so-called “live” vaccines eg:
BVD, IBR, PI₃, BRSV (combination), Rift Valley Fever, Lumpyskin disease and Three-day stiffness disease. Brucellosis vaccine (RB51) can also cause abortions and must therefore be vaccinated pre-breeding.
NB. Remember that preferably, no more than one "live" vaccine should be administered at the same time.
3.2 Inactivated (“dead”) vaccines
Can / should be given closer to the breeding season eg: Vibriosis and “Pink Eye”
4. Trace Mineral Supplementation
Trace minerals play a very important role in the fertility of cows, especially zinc (Zn), manganese (Mn), copper (Cu) and selenium (Se). Chromium (Cr) can also help with improved energy metabolism, which may benefit body condition.
During calving, the cow loses a third of her trace mineral reserves through the calf, the placenta and the uterine fluid.
The sooner these trace minerals are replenished after calving, the smaller the chance of a trace mineral gap during the mating season. Figure 4 shows the effect of an injectable trace mineral supplement at the critical times (pre-calf and pre-mating) on the liver's copper status.
Figure 4. Liver copper levels after strategic Multimin supplementation
Supplementation of trace minerals by means of an injectable supplement (Multimin Se + Cu + Cr Cattle) before the breeding season can lead to:
The ideal time for the pre-mating injectable supplementation of trace minerals (Multimin Se, Cu, Cr Cattle & ProVit A), is 4-6 weeks before the start of the breeding season. Combine with vaccinations to reduce handling and improve vaccine responses.
5. Parasite control
5.1 Internal parasites:
Internal parasites in cattle are generally considered as 'less important'. Although not always as 'visible' as in sheep, internal parasites can have a negative effect on the condition and performance of cows. A trial conducted by Dr Meaker (1994), showed the positive effect (increased conception rates) of deworming on the reproduction of first calf heifers and second calf cows. (Figure 5 & 6)
Figure 5. Effect of deworming on 1st calving heifers
Figure 6. Effect of deworming on 2nd calving cows
Even the calves of group treated twice benefited by weaning over 4kg heavier, because of the better milk production of their dams.
Liver fluke in particular, can result in large economic losses. In addition to all the other essential functions of the liver, it also affects the production of hormones - which are critical in the run-up to the mating season!
5.2 External parasites:
Treat external parasites (especially ticks) as necessary, to prevent / reduce the transmission of tick-borne diseases and mechanical damage to the udder and teats. A tick load can also negatively affect the appetite of cattle. This may affect conception and milk production.
The control of flies will also reduce irritation, which has a negative effect on grazing time.
6. General Management aspects
If selection can take place, now is a good time to pay attention to the following and identify cows that must not return to the bull:
Cows that had retained placenta’s should be examined for vaginal discharge / uterine infection and treated early.
Replacement heifers - as heifers that calved for the first time take longer to return to cycle (80-100 days), it is recommended that heifers being mated at least a month before the cows.