Lactation transition impacts cow health

The end of lactation is not only the conclusion of a milking period but also the preparation for the next one. Maintaining a good level of intake is a key element for a successful start and preserved health. Intake reflects the amount of feed, and thus nutrients, that a cow can eat in a day, explains Julien Jurquet, a project manager at the Institut de l'élevage.

Nutritional balance during dry period

Ensuring a good level of intake is essential to ensure that dry cows receive what they need, avoiding both deficiencies and excesses. During the dry period, the beginning of lactation is being prepared, where the demand for energy, protein, and calcium will be particularly high. If, on the contrary, intake is underestimated, the ration may provide more energy than needed.

Risks of excess body condition

The cow will store this energy and gain body condition. Excessive body condition increases the risk of energy deficit at calving because the animal is less able to mobilize its reserves. This increases the difficulties at calving. A good transition and sufficient intake are necessary to maintain the proper functioning of the rumen.

Rumen health and microbial balance

The dry period should not disrupt the dynamics of the microbial flora or the potential of the villi. It would be like stopping a well-functioning engine, with the risk of having difficulty restarting it, illustrates Dominique Landais, a nutrition and robotic consultant at Seenovia.

Maximizing feed intake

How to maximize intake? Before trying to concentrate the ration, it is already important to ensure that it is well consumed, specifies Julien Jurquet. This involves a homogeneous ration available at will throughout the day. If the ration contains straw, the strands should be cut short, ideally between 2.5 and 3 cm.

Improving ration appeal

Adding water, or even molasses, will make the ration more appealing, adds Dominique Landais. In parallel, cows must have sufficient access to water. It should be noted that the dry period does not require a severe diet. The cow should stay at most half a day in a pen with straw while organizing the change of barn, advises Dominique Landais.

Stressors during dry period

The cessation of milking and the separation from the herd are already significant stressors. The milk pressure in the udder will be sufficient to initiate the dry period. According to a synthesis of 42 trials, having a cation-anion balance (Baca) lowers intake in prepartum, mainly due to anionic salts that are unpalatable, but improves it in postpartum.

Impact of Baca on production

In multiparous cows, the benefit is more pronounced with a clear increase in production at the start of lactation and a reduction in the risks of milk fever and retained placentas. In primiparous cows, a negative Baca does not show a favorable impact on the level of production in the first lactation. A good compromise would be to aim for a Baca between +50 and -50 meq/kg MS, with good feeding practices.

Balancing acidification and intake

If moderate acidification has shown its interest, there is more to gain by increasing intake than by trying to achieve a very negative Baca (below -50), estimates the consultant. Phosphorus sensors are a path to explore to lower Baca without experiencing appetite problems. This allows for a decrease in milk fever. But phosphorus plays an important role in energy synthesis. The question arises of the impact of a deficiency on production, questions Dominique Landais.

Intake levels in dry cows

The intake of dairy cows is well known, not necessarily those of dry cows, acknowledges Julien Jurquet. At the experimental farm of Trinottières in Maine-et-Loire, thanks to weigh scales, the intakes of dry cows were measured over three years, with a ration based on maize silage, straw, and rapeseed cake.

Findings from the study

This monitoring showed that the intake was on average 17 kg MS, more precisely 15.7 kg for primiparous cows and 17.7 for multiparous cows. It is more than what we thought, notes Julien Jurquet. There is a 3 kg difference with the intake on which the Inrae feeding tables are based. The study also showed that the decrease in intake is only really marked in the last two weeks before calving.

Correlation between dry period and lactation

Another finding that encourages providing a ration at will: Cows that ate the most during the dry period were also those that ate the most during lactation, hence those that produced the most, indicates Dominique Landais.