By Debbie James

A Pembrokeshire dairy farm is improving performance from maize silage by balancing it for the two most limiting amino acids, enabling cows to be fed a lower crude protein ration and improving nitrogen efficiency.

The Smith family grow 110 acres of early maturing maize in medium loam soils at Pelcomb Farm, near Haverfordwest.

Maize provides a consistent base forage in the total mixed ration (TMR) fed to the autumn calving herd of 450 Holstein Friesian cows.

The ration is formulated for 38 litres and includes 19kg maize silage, 18kg first and second cut grass silage and 9.75kg blend.

Last autumn, working with their nutritionist, Ken March, of Perfekt Cow, they used a new ration formulation programme that more precisely balances protein in the diet by looking at key amino acids.

Lysine and methionine have been identified as the two most limiting amino acids for lactating dairy cows fed maize-based rations and this has a detrimental influence on milk quality and yield.

By adding lysine and methionine at optimal levels to the TMR at Pelcomb Farm – in their case a balanced supplement fed at a 100g/cow – the beneficial impact on milk quality was immediate, says Peter Smith, who farms with his brother, Mike, and their parents.

“We had been running at 3.35 per cent protein but when we balanced the ration for amino acids it increased to 3.5 per cent overnight and it continues to run at that.’’

The reason for this is that the cow’s nutritional needs can be met when the diet delivers optimal levels of lysine and methionine within metabolisable protein.

“Last year we included these in the cow ration for the first 120 days post-calving and the improvement in milk yield and quality more than covers the cost of the product,’’ says Peter.

“This year we fed the amino acid mix in the dry cow ration for the three weeks pre-calving and that has had an even more positive influence. We have had no calving issues, cows are cleaning up much quicker after calving and, because of this, fertility is looking much better this year.’’

He says that overall, herd yield has increased by around 1,500 litres a day.

The current annual average milk yield per cow is 9,000 litres at 4 per cent butterfat and 3.5 per cent protein with 3,600 litres produced from forage

As well as excellent nutrition management, producing high quality forage is another key focus area for the 650-acre business.

Maize has been grown on the farm for the last 20 years, as a reseeding tool initially.

“The farm was traditionally all grass and had been heavily stocked before we took on extra land so we never had the opportunity to reseed. By growing maize we have reseeded the whole farm,’’ says Peter.

A field supports a maize crop for two years followed by winter wheat for two years before a grass ley is established.

Seed is drilled in the first week of May and harvested in early October with an additive used for ensiling.

The variety grown is Afgriaxx, selected because of its early maturing characteristics and its high starch content.

“What we like about maize is that it is very consistent in the silage clamp, it is always around 30 per cent dry matter (DM) and 30 per cent starch,’’ says Peter.

Yield varies according to growing conditions but is mostly around 18 tonne (t)/acre.

Five years ago, the Smiths shifted their calving pattern from an all year-round system to autumn block calving.

Ideally, they like to have sufficient maize in reserve from the previous autumn’s harvest to include in the ration when the first cows to calve are housed from August 1.

If stocks are in short supply, some of the winter wheat is wholecropped to fill the forage gap.

“It gives us another option,’’ Peter explains. “Also, if our grass silage yields are down but the maize has done well, which has been the case in the last two dry summers, we will wholecrop the winter wheat to fill the gap. It reduces our risk.’’

Cows receive 24kgDM/day in the TMR, of which 14.5kgs/DM is forage, made up of a 50:50 ratio of maize and grass silages.

“We will feed the cows as well as we can through the winter and once they are in calf we graze them like a spring calving herd and get as much milk as we can from grazed grass,’’ says Peter.