Balance grass correctly to maximise returns
27 March 2019
With forage shortages in many areas, turnout cannot come quickly enough for many dairy producers, but a balanced buffer ration to accompany grazed grass should be prioritised to maintain performance, cow health and fertility.
For grazing herds fresh grass is the cheapest feed available and turnout provides a welcome opportunity to reduce feed costs. According to Charlotte Ward, Trident technical manager, maximising this value is essential.
“Turnout does introduce a series of challenges, not least estimating grass nutritional value and supply, in an attempt to maintain cow performance,” says Miss Ward. “Failing to correctly balance grazed grasscould lead to significant losses in production, cow health and fertility.”
Feed intakes
During the grazing period, Miss Ward explains producers can expect to see daily intakes of grazed grass vary by 8kg dry matter (DM), with daylength, grass availability and grass quality all contributing to what intakes can be achieved.
“In early spring, cows will only eat around 6kg DM of fresh grass. However, in comparison, during the early summer months when daylength, grass quality and grass availability are high it’s possible to reach intakes of 14kg DM of grass.
“A balanced ration of adequate quantity and quality at turnout is therefore essential for cow health and production, especially for fresh calvers and high yielders who can’t meet requirements for maintenance plus milk from grass alone,” she says.
Correctly-balanced buffer ration
Forage is the foundation of any buffer ration, with maize and whole crop particularly well-suited providing fibre and some slowly fermentable starch. They are also low in protein which complements the high protein of fresh grass.
“With spring grass low in structural fibre and high in soluble sugars it’s important to boost the fermentation of fibre in the rumen to increase the supply of milk fat precursors and maintain butterfat production,” says Miss Ward.
She highlights that the neutral detergent fibre (NDF) level of the buffer ration should be between 34 to 38% to optimise rumen fermentation.
Miss Ward adds that buffer rations should also include chopped straw as this will provide the “scratch factor” which will help optimise rumen health. “Additionally, including highly digestible fibre straights, such as sugar beet pulp, alongside forages, will supply a source of slowly fermentable energy supporting rumen function and butterfat levels,” says Miss Ward.
For producers on solid contracts, or for those still struggling to meet stipulated milk fat levels, Miss Ward adds that feeding a protected fat can provide a cost-effective option to boost milk fat. “Feeding a supplement that is high in C16 fatty acids, such as Butterfat Extra, will lift milk fats significantly by supplying essential fatty acids to drive milk production.”
She highlights that feeding starch and small amounts of sugar is also important to supply energy to rumen microbes to harness the abundance of rumen protein. “The ideal starch supply is from maize or whole crop. In addition, starch and sugar from purchased feeds such as maize meal and molasses can be fed, or homegrown rolled cereals providing they’re balanced accordingly,” says Miss Ward.
Producers should be aiming for a ration DM of around 45% to minimise sorting and encourage intakes. Feeding molasses helps to not only achieve the ration DM but also improves ration palatability and therefore DMI, but Miss Ward warns that it should not be fed at more than 1kg/head/day, particularly in early spring and summer due to high sugar levels in fresh grass. “Sugar can act as a laxative making muck very loose, if this occurs it can result in nutrients passing through the animal without being utilised,” adds Miss Ward.
“Fresh grass can have a protein content of up to 27% or more with the majority of it being rumen degradable (RDP), resulting in diets running at higher protein levels than normal are unavoidable. Therefore, any protein supplied within the buffer feed should have a good level of digestible undegraded protein (DUP).
“Feeds such as NovaPro or Soypass are ideal protein supplements to feed in a buffer ration as they both supply high levels of DUP without overdoing rumen protein,” she notes.
“It’s also important to monitor milk ureas. If levels rise above 30mg/100ml then action must be taken to avoid negative impacts on production, health and fertility.”
Mineral supplementation
Miss Ward also advises that grass is probably one of the most unbalanced feeds with regards to vitamins and minerals and without adequate supplementation cows can end up drawing on their body reserves.
“Symptoms are often only seen once it’s too late and therefore buffer feeds should contain a vitamin and mineral supplementation that recognises a higher feeding rate of grass as a proportion of the total diet,” she says.
Hypomagnesemia is perhaps the most common mineral issue at grass, particularly at spring turnout, occurring due to a low level of magnesium in the blood.
“Cows don’t have large readily available reserves of magnesium and only a small proportion is absorbed from the diet. The main risk period is in the early grazing season, because magnesium is less available in young lush grass, especially if it’s rich in nitrogen or potash.
“To mitigate the risk ofhypomagnesemia, avoid potash application in the spring and ensure the diet contains an adequate level of magnesium during critical times. Add 30g/cow/day of magnesium to the ration from calcined magnesite and soluble sources such as magnesium chloride can also help mitigate risk,” adds Miss Ward.
Plan turnout wisely
“Planning ahead before turnout is crucial to maintain performance, health and fertility. Ensure you assess pastures and monitor sward height and density to make the most of the grass available while providing a balanced buffer ration to complement grass and avoid any nutritional shortfalls,” concludes Miss Ward.
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