In this study, the S:W ratio was calculated for the year 2020, on 2,400 Friesian cow farms, located in the Po Valley of the Lombardy region. The calculation was based on official data from functional controls, collected by AIA technicians. The information considered included milk yield corrected for fat and protein content at 4.0% and 3.3% respectively (FPCM), milk fat and protein percentage (%), somatic cell count linear score (SCC) and conception rate (CR%), for all inseminations carried out in the summer and winter of 2020.
The study also focused on a group of 99 farms participating in the Element intensive cooling programme of Arienti, a manufacturer and installer of farm cooling systems.
The monthly averages for the three years considered of the milk production and conception rate of the 36 farms that started the Arienti Element programme in 2019 are shown in Figure 1. The graphs describe how the performance of the cooled cows evolves over the three years considered.

Figura 1 – Monthly averages of (a) corrected milk (kg/cow/day) and (b) conception rate (%) on all registered inseminations.

From the data represented in figure (a), we can see a clear trend of continuous growth of the average production per cow. The average winter production per cow increases from 35 kg in the year before the start of intensive cooling to 38 kg and more in the summer of 2020, where cooling has been adequately provided for two consecutive summers. It can also be seen from the graph that the difference in production between summer and winter goes from 4-5 kg per day to 1-2 kg in the following years. As can be seen in figure (b) the conception rate gap in 2018 was 10 percentage points (going from 45% winter to 35% summer), while after two consecutive years of cooling the decrease is around 5% (going from 50% winter to 45% summer), i.e. half of the decrease compared to the year before the start of cooling, but above all achieving summer reproductive performance almost comparable to the winter performance in the pre-cooling period.

As can be seen from Table 2 and the two previous graphs, the improvements in production levels after the first summer of intensive cooling are less than those achieved in the second summer (about half of the improvement in the S:W index), while as far as reproduction is concerned, the improvement is already completely achieved in the first year.

The continuous improvement in summer milk production in the two years analysed can be attributed to the fact that the intensive cooling of the cows in summer helps them to eat more and, although they produce more, they are still able to accumulate more body reserves in the last phase of lactation and lose less in the first phase of the next lactation, especially when this transition phase takes place in summer. In this way, cows maintain a better body condition that positively influences both milk production and fertility in general, especially in the summer months. The improvement of CR already in the first year of intensive cooling has as an immediate consequence the decrease of the average calving distance (average DIM), with the consequent increase of the average farm production and the improvement of udder health.

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