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Cattle and the heat wave: -10% milk output, but high-quality forage helps contain the damage

An expert's opinion on how to reduce the impact of high temperatures in summer


We are all suffering from the heat wave these days... particularly cows, dairy farmers and their financials.

According to the Italian farmers' association Coldiretti, this unusually hot summer has caused many expenses, such as extra water for the animals and energy to ventilate stables.

But revenues, too, are impacted: because of the heat, animals lack appetite, so they don't eat much and produce less milk. This means fewer profits for the farmer.

In summer, feeding cows with high-quality forage is more important than ever.

According to Davide Reginelli, head of the Angelo Menozzi - Landriano (Pv) Educational and Experimental University Farm, with about 100 dairy cows:

"When the cow has trouble eating, such as during the summer, the output is lower, but an appetizing forage is precious to compensate for the decrease in production."

A clean forage that is not polluted by stones and soil, rich in protein and digestible fiber, ensures animal welfare and improves its performance; farmers know that haymaking operations - especially raking - are strategic for obtaining top quality forage.

RA-Rake is an innovative double-wheel rake; produced by Italian agricultural machinery manufacturer Repossi, it is equipped with two stars of different diameters. The larger one never touches the forage, but activates the second smaller star, which moves the forage without polluting it with stones and soil.

As part of a Horizon 2020 European project, researchers at the University of Milan carried out several scientific tests on forage harvested with RA-Rake and compared it with the one gathered by  a rotary rake.

These tests have revealed that forage raked with a rotary machine presents a higher ash increase, when compared to RA-Rake. In fact, RA-Rake generates an increase of ashes in the forage 66% lower than the one obtained with the rotary rake. Because of the difference in ash content, the forage obtained with a rotary rake has a lower content of Net Energy for Lactation (NEL) per kilo of dry matter, expressed in 0.287 MJ.

Since the animal has to assimilate, on average, 3.093 MJ to produce one kilo of milk, these missing 0.287 MJ per kilo of dry matter mean that the difference in daily output (RA-Rake vs. rotary) due to the different ash content in forage can be calculated in 0.8 kilos of milk per animal. In other words, all other things being equal, when the cow is fed with forage produced with RA-Rake, it produces 0.80 kilos more milk every day.

In fact, according to Reginelli, university expert and farmer, "...if the feed is better from a nutritional point of view and its protein content is higher, the mixture is richer in digestible fiber, so the cow responds by better ruminating and producing more milk."

In economic terms, this is a significant productivity impact!

The implications are noticeable: all other things being equal, for a 250-cow herd, at the end of the year the total output will be 73,000 kilos higher, so the farmer will have an extra €23,000 in his pocket,  when using RA-Rake instead of a rotary machine (milk price 0,32 €/l).

Of course, the economic impact is higher for larger farms, but even for a small stable the calculation is interesting. Since there is no increase in farm costs, the extra income obtained by selling more milk just means extra profits.

These considerations confirm the assumptions made at the beginning of the Horizon 2020 European-backed project and encourages the adoption of this innovative machine, so revolutionary in its simplicity.

What is Ra-Rake

For over a century Repossi Macchine Agricole has been designing and producing combed and rotary rakes; the latest addition to the range of rakes, RA-Rake, is the revolutionary double star rake, thanks to which in 2017 the company obtained a prestigious Horizon 2020 funding, launched by the European Union to promote and support innovation, research and technological development.

The innovation, ingenious but simple, allows you to take advantage of the advantages of star rakes without having to bear the negative consequences on the forage: according to research by the University of Minnesota, the star rake is in fact the fastest and cheapest, but is also the one that collects more stones and soil.


In fact, the single star, mechanically driven by the clutch with the ground, moves the hay, but in this way pollutes it with a large amount of ash. Gabriele Repossi, the inventor of the new machine, had the idea of equipping it with two stars of different diameters: the larger one did not touch the forage, but had the sole task of moving the second star, the smaller one, which moved the forage without polluting it with stones and soil.

Since the rake does not need complex and expensive mechanisms to move the smaller star, it benefits from reduced costs (both purchase and maintenance) and allows it to operate at high speed, a peculiarity of the star rakes.

Source: Repossi Macchine Agricole srl