WITH July having now arrived, most of us will assume that summer, if not quite here already will, at the very least, be just around the corner.

Although most will acknowledge that the seasons are changing somewhat, there are some patterns of nature that we can reliably predict - one of which being summer grass growth.

We are all aware that there is nothing quite like good, early spring grass for all cattle, but there is a huge temptation for farmers to assume that the quality of their summer grazing is not too dissimilar and, in so-doing, milk yields, health and fertility could be put in jeopardy.

As soil temperatures start to warm up during February, so grass growth starts to accelerate with quality being at its peak in early March with D Values and ME's being 83 and 13.28 respectively. As the plant continues to grow, yield is increased but at the expense of quality with average D Values being 76 on April 29, dropping to 63 by June 18 when seed production, flowering and lignification takes over.

The quality does not improve in the short term with average D Values for all perennial ryegrasses being around 64 throughout the whole of July and August and with the plant seemingly taking a well earned rest before a secondary peak in early autumn, quantity is also down.

The cows, however, still need to be fed and if production is going to be maximized, then the feeding programme needs to be formulated with a great deal of reality. We have experienced very good growing conditions this spring, but unfortunately, a combination of high rainfall and lowish temperatures has rendered a lot of both first and second cut silage rather low in energy.

Pete Davis, a ruminant nutritionist who has recently joined animal feed compounders Harpers Home Mix Ltd., has long argued the case for an appropriate complementary buffer feed during the summer months and is particularly concerned this year as a lot of the silage being fed is generally poor quality silage from last year's harvest. With silages from this year also appearing to be variable, the concentrate proportion of any buffer must be formulated with great care.

Pete told me that there are a lot of dairy farmers with expectations of M + 20 litres off spring and summer grass but in reality, their yields were closer to M + 12 litres during May and June and, in all probability, will be down to M + 10 litres throughout the summer. Cows that have been expected to achieve over 12 litres this spring from grazing are more likely to be giving poor milk protein and have become thin due to them mobilizing body fats in order to make up the shortfall.

"There seems to be a bit of an unwritten rule," he said. "Most diets seem to have a 2-5 litre shortfall."

An example would be a dairy farmer feeding 3 kgs of blended concentrate in the summer, alongside a buffer feed of between 10 - 15 kgs of grass silage and all day and night grazing. Many of them would expect M + 22 litres from this but the concentrate, even at 13 ME, is only supplying enough energy for six litres, thus leaving 16 litres to be taken from grazing and the buffer feed.

When this is happening, we are seeing lean cows. In order to maximize summer production, I would suggest that in this scenario, they increase their concentrate usage to 5 kgs of a complementary feed such as one of our Summer Buffer Mixes which is a combination of wheat, sugar beet, barley and soya. This not only helps the cow toward maximum efficiency, but also helps her put back her body condition, keeps her healthier and improves her fertility.'' "The message is quite clear," said Pete. "If farmers continue to be unrealistic with their predictions and expectations of summer grazing, the cow will suffer. She either milks and does not get in calf, or she gets in calf and does not milk - rarely will she do both," he said.

Other examples of a good complementary buffer feed would be forage maize or wholecrop wheat and if there are one or two farmers out there who are currently growing wheat but do not have sufficient storage bins, they could consider wholecropping it for next years buffer feeding rather than sell it off the field.

As reported last month, all our maize trial sites were drilled on time and with subsequent favourable weather conditions, everything is up and away and looking quite healthy.

We visited all sites between June 11 and 12 and conducted an early vigour report and, overall, all sites are looking quite positive. There are, however, a few varietal differences, but nothing like as severe as last year - at least so far anyway.

Cornwall Farmers Site, Tregony, Near Truro: 13 varieties were drilled on May 9 with Sapphire, Destiny and Hawk just leading the way with seven main leaves with the eighth leaf just coming through. Most of the remaining material had between six and seven leaves with perhaps Pioneer's D60 just short of the pace and showing clear signs of stress.

Mole Valley Farmers Site, Newquay, Cornwall: 26 varieties were drilled on May 6 and with eight breeders being represented on a somewhat marginal site, albeit under pretty good conditions thus far, differences were inevitable. Although most varieties had between six and seven leaves, there were still quite notable differences in plant vigour and colour, with ES Ballade, ES Potter and Acclaim just ahead at this stage, followed very closely by Artist, Avenger, Aurelia and Challice.

There were a number of varieties just behind the leading seven, but RH0721, NK Jasmic, NK Nigella and NK Paddy were the four varieties that were the weakest looking and exhibiting the most stress.

Advanta Site, Shebbear, W Devon: 15 varieties were drilled on 15th. May and although the site has a slight westerly slope, it is rather exposed, very marginal and will be quite a test. Most material had five leaves with Avenir, Destiny, Hawk, Sapphire and Avenger looking the strongest at the moment with Pioneer's A44 and D60 having the smallest plants.

Mole Valley Farmers Site, Bridgwater, Somerset: 24 varieties were drilled on 7th. May, but the favourable site conditions have already contributed an extra couple of leaves in most cases. Artist is just ahead of the pack with eight leaves, followed closely by Acclaim and NK Nigella, with the bulk of the remainder just behind those three. Even though this is a most favourable site, there were still three varieties that appeared to be the weakest which were ES Time, ES Secret and Anjou 209.

Pearce Seeds Site, Rosedown, Dorset: Pearce Seeds have established a number of maize trials this year with their trials officer, Robert Baker said: "All trials have made a good start this year with one or two needing treatment for slugs. Destiny has emerged very quickly and is currently showing the best colour.

"Leaf sizes and lengths do vary a little with some material showing more purpling' than others. Hawk and Avenger from Advanta also look strong as do Agassy and Cadwell from Maisador. All KWS material looks to be average, but the Syngenta material appears for the moment to be below average. Their soil temperature records show a drop to below 10 degrees C at the end of May and this has certainly contributed to individual varietal differences with both colour and progress being affected. All varieties have responded in a positive way since the start of the better weather just over a week ago.

And finally. Weeds were evident on all sites and as this good spell of weather is resulting in the maize starting to move, you can be sure that the weeds will not be far behind. Remember the old adage of "knee high on the July 4"- you've still got time to control the secondary flush, but don't hang about - it won't be long before the rows close.