South Africa

Health Care

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Preparing of Cows for the Breeding Season Part 1

(This is article 1 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:

1.  Nutrition and Body Condition

The body condition of cows in the run-up to the mating season is crucial to ensure success during the mating season. During this time (between calving and the mating season) the following happens:

  • cows' milk production increases
  • cows' reserves are drained
  • cows’ lose mass and body condition (especially if the nutritional conditions and / or supplementation are not as desired) 

Cows easily lose one body condition point in this time. If they have calved down in an ideal body condition score of 3.5, it can come down to 2.5 (and even less under difficult conditions). It is crucial to get their body condition score back to a minimum of 3 and preferably 3.5 by the time the breeding season begins.

If cows' body condition score drops below 2.5, they will need to receive special attention in terms of their nutrition. Better grazing and / or supplementary feed such as hay or silage, together with a production lick can help. Although this exercise it is not cheap, it is necessary to ensure a good conception rate in the coming mating season.

If it is not done, the next could be your destiny:

  • cows that conceive rather later than earlier in the breeding season
  • cows that even skip the breeding season does not conceive at all
  • an extended inter-calving period
  • calves that wean lighter (a combination of lower milk production and calves born late in the next calving season)

This once again emphasizes the importance of cows being in good condition with calving. It is easier and cheaper to maintain or improve the condition of cows over an extended period from weaning to calving, than to have to take drastic steps at this late stage to correct their body condition! 

Figure 1 shows the effect of body condition score on conception at the beginning of the breeding season:

Figure 1: The relationship between condition score with mating and conception

Figure 2 is an example of a cow in an acceptable condition at the beginning of the breeding season, while the cow in figure 3’s body condition is not recommended.

Figure 2: Condition ready for mating season      Figure 3: Condition not suitable for mating       

Consult a nutritionist on the best options for the specific conditions and available resources if the body condition of cows need to be improved.

2.  Breeding fitness

Certain conditions can undo all the other management inputs to achieve a good conception rate and calving percentage! 

If a sudden decrease in calving percentage is experienced or calving percentage remains low over the long term despite good condition etc., we must look out for the following:

2.1 Vibriosis (Campylobacter fetus)

This is a sexually transmitted disease where the cows are infected by infected bulls. The most common symptoms in the cows are abortions, low conception rates, prolonged calving intervals and uterine infections. Cows do develop immunity but this is not permanent.

Bulls are asymptomatic (do not show symptoms), serve as carriers and are the main source of infection. Vaccination before the start of the breeding season is an option in positive herds.

2.2 Trichomoniasis (Trichomonas fetus)

It is also a sexually transmitted disease where the cows are infected by infected bulls. The most common symptoms are resorptions (early loss of pregnancy), a prolonged calving interval and abortions (but not common). Although most cows become self-healing after a few cycles, they will most likely not be pregnant at the end of the breeding season.

Usually bulls are tested. Bulls that are positive should be slaughtered. Treatment is very difficult, expensive and not always effective. Replace positive bulls with young maiden bulls for breeding (or perform AI).

2.3 Brucellosis (Brucella abortus)

This is one of the most important causes of poor calving percentages! NB. The disease is also a zoonosis - a disease that can be transmitted from animals to humans - mainly through unpasteurized (raw) milk and exposure when abortions, stillborn calves and retained placenta’s are handled without gloves. It is a controlled disease and should be reported to the state veterinarian.

Cows are infected through environmental contamination. The newborn or aborted calf, the placenta and the amniotic fluid of positive cows contains a lot of bacteria and serve as the main source of infection. Cows usually abort once and then calve normally - BUT - will always remain a carrier and source of infection.

Test the herd on a regular basis for the presence of brucellosis, especially if there are positive herds in the immediate area. Biosecurity is crucial. All new animals purchased must be certified brucellosis-free. Keep border fences in good condition.

Vaccines are available to prevent abortions, but can not cure the disease! By law, all heifers must be vaccinated. Two vaccines are available:

  • S19 - heifers must be vaccinated before the age of 8 months
  • RB51 - may (should) be used on
    • heifers - more than once from 4 months up to first mating 
    • cows - only on non- pregnant cows (may cause abortions)

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