Maize silage plays a central role in the farming system on a Cornish dairy and beef farming business better known for the production of oysters and mussels. 

Porthilly Farm near Rock on the Camel Estuary is home to the Marshall family, who in addition to a herd of 230 dairy cows and 500 head of beef and youngstock, have for 30 years run the Rock Shellfish Company which grows approximately two million oysters and 180 tonnes of mussels per annum for retail and wholesale. 

All family members work across both parts of the business as required. Chris and Matt Marshall are primarily responsible for the farming enterprise, while their uncle Tim and his son Luke focus on the shellfish. Their father Jerry manages the office operations for the entire business. 

The farm totals 550 acres, all close to sea level and is predominately down to a mix of temporary and permanent pasture. Every year around 90 acres of maize and 90 acres of cereals for crimping are grown. The farm had been run as an organic unit, but five years ago they went back to a conventional system. 

"We found organic too limiting and the decline in the organic premium coupled with the higher feed prices meant the economies did not work," Matt Marshall comments. "In addition we wanted to increase cow numbers and we could not do this and remain organic."

The herd is predominately autumn calving as it suits the farm which can dry out in the summer as Chris Marshall explains. 

Maize is an important forage on the farm and the Marshalls work closely with Forage and Arable Specialist Louise Woolacott and Nutritionist Matt Jenkin from ForFarmers to ensure the crops deliver in the field and in the diet. They had grown maize before they went organic and were pleased to be able to re-introduce it. 

"The farm is very dry and maize enjoys the heat and can take a degree of drought," Louise explains. "It also fits the farming system well."

The Marshalls grow a maximum of two years maize back to back and it is followed by grass or spring barley for crimping. If maize has been grown on steeper fields, Interval, a rape kale hybrid from Limagrain will be sown to reduce soil erosion, either being ploughed in or fed to sheep.

“When selecting varieties we are looking to produce a crop at around 35% dry matter and 35% starch to balance the rest of the diet,” Louise continues.  “So we look closely at dry matter yield and the factors affecting quality, particularly starch content and cell wall digestibility.  And we want a good ratio of cob to plant.

“While 100% of the cob is digestible, half the total energy is in the vegetative part of the plant.  So it’s also important to consider how much nutrition can be derived from the rest of the plant which is indicated by cell wall digestibility.  Cell walls make up a large part of the maize plant structure and the higher the cell wall digestibility, the greater the availability of nutrients. Finally we need early maturing varieties as maize needs to be incorporated into the milking cow diet as soon as is practical."

"This year the main varieties were Fieldstar and Pinnacle, both from Limagrain. Pinnacle is a new LGAN accredited variety and one of the highest starch yielders combined with high cell wall digestibility. This means it provides an excellent balance of energy from both starch and digestible fibre, leading to a high ME content in the silage."

LG Animal Nutrition (LGAN) varieites have the genetic potential to deliver superior nutritional value, whilst maintaining excellent agronomic qualities and yield, thereby improving ration performance. 

Maize was drilled on 25th April and was all harvested by 5th October. Ten acres are harvested in early Septemeber every year to provide maize to the earliest calvers. Yield across the 90 acres averages 15t/acre. The crop analysed at 35.7% dry matter, 11.5ME, and 38.8% starch. This yearly crop will not be analysed until it has had time to ferment completely. 

Matt Jenkin says having good quality maize is the foundation of all diets fed on the farm. He says dry matter content is important as it helps drive total dry matter intakes. 

The winter TMR which is fed once a day comprimises of first cut grass silage, maize, crimped cereals, hipro soya, rapemeal, sugar beet pulp, straw, Lintec, protected fat, minerals and water to bring the total TMR to 46% dry matter. 

“The balance of forages allows us to build a balanced diet for M+28 litres outside and cake is then fed to yield above this to a maximum of 4kg,” Matt explains.  “Lintec is included from September to December to provide omega-3 fatty acids to support fertility and is withdrawn when the majority of the herd are back in calf.  Fertility performance has been improving consistently which is essential given the aim to tighten the calving block.

“We also feed maize to dry cows as part of a partial DCAB system.  Kept outside on minimal grass, they receive a TMR comprising chopped straw, maize, rape, soya, minerals mag chloride and gypsum.”