Reproductive function is a “luxury” function in dairy cows, meaning that reproductive performance is reduced as soon as the animal’s health status deteriorates.
Fertility problems in dairy herds can therefore have various causes, which can be grouped into two main categories:
- Those that limit the onset of oestrus, such as poor dry period management, for example.
- Those that lead to returns to oestrus or abortions.
The economic impact of fertility issues in dairy farming is far from negligible, as a 10% decrease in first AI success rate represents a cost of €63 per cow, not including the additional replacement costs.
The key dry period management practices to implement in order to promote the onset of oestrus are outlined below.
Avoid excessive body weight fluctuations
It is generally accepted that a cow may lose body weight at the beginning of lactation in order to meet production requirements, and then regain it later. This situation is physiological. However, if this weight loss during the first two months of lactation is too significant—exceeding one body condition score point—the expression of oestrus will be limited. It is therefore necessary to:
- Provide, during late gestation and preparation for calving, a sufficiently fibrous ration to maintain maximum intake capacity without excessive fattening, which could otherwise penalise intake capacity at the start of lactation.
- Provide, at the beginning of lactation, a ration sufficiently rich in easily digestible energy (sugars).
Note:
- A common mistake in dairy cow feeding is to rebuild body reserves only during the dry period. Ideally, a cow should have fully restored her body condition before the dry period and should only maintain it during late gestation. For the highest-producing cows, regaining up to 50% of body condition during the dry period may be acceptable; beyond this level, fertility will be compromised.
- In large herds, poor management of body condition score is characterised by a decrease in reproductive performance (–10% success rate at first AI or more) in second-calving cows.
Ensure an easy calving and proper placental expulsion
An easy calving and proper placental expulsion are essential to maintain reproductive performance.
If calving lasts too long, muscle tears may occur. Likewise, poor placental expulsion promotes the development of metritis and the persistence of a corpus luteum, which blocks the cow’s hormonal cycle and therefore the expression of oestrus.
Ease of calving and quality of placental expulsion are determined by the quality of uterine muscle contractions, enabled by calcium and magnesium.
This is why adequate mineral nutrition is essential during the dry period, particularly in the 15 days before calving. Magnesium supplementation may also be required to ensure strong muscle contractions. Mineral supplementation must also provide sufficient trace elements and vitamins to ensure good colostrum quality and an optimal start to the next lactation.
Other factors influencing reproductive performance
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Nutritional factors: deficiencies, excess urea in the ration, etc.
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Management-related factors: slippery concrete limiting mounting behaviour, metritis, etc.
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Health factors: BVD, etc.
To conclude
Because it is a period with less direct contact with the animals, the importance of the dry period is too often underestimated, even though it is essential for optimising reproductive performance.
It should no longer be seen as a phase “during which the cow recovers from lactation”, but rather as a period “during which the cow prepares for the next lactation”.
Reproductive function is a “luxury” function in dairy cows, meaning that reproductive performance is reduced as soon as the animal’s health status deteriorates. Fertility problems in dairy herds can therefore have various causes, which can be grouped into two main categories: Those that limit the onset of oestrus, such as poor dry period management, for […]
...Reproductive function is a “luxury” function in dairy cows, meaning that reproductive performance is reduced as soon as the animal’s health status deteriorates. Fertility problems in dairy herds can therefore have various causes, which can be grouped into two main categories: Those that limit the onset of oestrus, such as poor dry period management, for […]
...Reproductive function is a “luxury” function in dairy cows, meaning that reproductive performance is reduced as soon as the animal’s health status deteriorates. Fertility problems in dairy herds can therefore have various causes, which can be grouped into two main categories: Those that limit the onset of oestrus, such as poor dry period management, for […]
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