Clover inclusion Using white clover in mixtures with perennial ryegrass in a farm system can boost sward production and lead to higher milk solids production. Previous research has shown that white clover use can reduce the need for chemical nitrogen in- puts due to a process called biological nitrogen fixation, which occurs in the root nodules of the white clover plant. However, despite these benefits, white clover is still not being fully exploited on many dairy farms. In other research over a three-year period, diploid and tetraploid swards produced the same amount of grass, but when white clover was included there was an extra 1.5t of herbage DM produced each year (17t compared to 15.5t DM/ ha/year). The white clover content declined from 36% to 18% over the three years but this still maintained higher sward DM production than swards without any white clover. Overall, for every 1% increase in clover content there was an increase in herbage production of around 40kg DM/ha. In addition, swards containing clover were grazed out more efficiently, as shown by a decrease in post-grazing height from 4.32cm in pure grass swards to 3.91cm in grass/ clover swards. The grass/clover swards also had improved nutritive value in terms of digestibility and protein content.
Managing white clover swards White clover is clearly a very different plant from perennial ryegrass, with a different growing habit. It has a lower winter growth rate but has a much higher growth rate in summer and autumn. This means grass/clover swards often have a lower opening farm cover in spring but shorter rotations in summer, due to the extra forage being produced. As white clover has high protein and is highly digestible, there is a risk of bloat, but only when sward clover content is high (typically over 40%).
Cows can be picky eaters in- deed. This taste preference can be boiled down to the choice of grass variety used to seed the field.
▶ ALL ABOUT FEED | Volume 29, No. 9, 2021
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PHOTO: CHRIS MCCULLOUGH
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