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Well planned buffer feeding the key to grazing success

With moist feed supply tight and silage volumes already low in parts of the country, planning spring buffer feeds early will be vital this year. And according to Trident technical manager Dr Michael Marsden, a well managed transition out to grass is important not just for its immediate impact on milk yield and quality, but also for its effects on both the rest of the lactation and cow longevity.

“Buffer feeding is about feeding cows for the future, not just the present,” he states. “Particularly for the fresher cows, any feed cost savings made by cutting corners in the spring will cost much more later in the year when trying to regain lost production or replace good cows culled due to poor fertility.

“The main constraint in the spring is a shortage of energy, resulting from the combination of grass protein levels driving milk yields and an over-estimation of grass intakes. With grass oils promoting a good, shiny coat, it’s easy for these shortfalls – which could result in body condition loss of 1-2kg/day – to go unnoticed until poor fertility and low milk proteins show up a few months later.”

By then the damage has been done, with those cows hitting peak lactation during the grazing season most at risk. Comparing peak yields from the last few years by month of calving will show if spring and summer calvers are peaking lower than those calving during the winter months, which is often the case and a good indication that improved management of buffer feeding is needed.

“The aim is to maximise the feed value obtained from grazed grass – still the cheapest of all feeds – by recognising its limitations and providing suitable ‘balancing’ feeds,” continues Dr Marsden. “Spring grass crude protein levels, for example, can be as high as 30%, compared to an early lactation cow’s requirements of just 18%.”

Capturing or reducing this excess protein (mostly effective rumen degradable protein, ERDP) is one priority, with the excretion of any excess requiring energy that should instead be going into milk production. It means that high fermentable energy, low protein feeds like maize silage and wholecrop cereal silage are a better starting point for forage-based buffer feeds than grass silage, maximising the capture of grass ERDP in the rumen.

“The other key nutritional aims are to maintain feed intakes, make up the inevitable shortfall in digestible fibre to support butterfats and good rumen function, and supply the necessary rumen-bypass protein that’s needed for high yields, but is lacking in grazed grass,” Dr Marsden explains.

“Start by being realistic about grazing intakes, which are rarely more than 1kg DM/hour even when grass quality is good, weather conditions are settled and cows are actually grazing. Achieving the 22-24kg DM/day intakes needed to support 35-40 litres/cow just isn’t possible without significant extra feed, and certainly more than the 8kg/day maximum possible in the parlour.”

Accurate pasture monitoring will provide early warning of potential reductions in grazing availability, whilst initially limiting cows to no more than 2-3 hours grazing each day will help smooth the transition. If conditions are cold and wet, select the driest fields for grazing, create additional access points to reduce poaching and use a back fence to further limit damage and allow swards more time to recover.

“Where grass and forages are wet, avoid excessive use of moist feeds, focusing instead on high-fibre dry feeds like sugar beet feed and soya hulls,” advises Dr Marsden. “If forages are in short supply, whether due to limited silage volumes or poor grass growth, consider using straw to maintain rumen function, combined with liquid feeds like Rouxminate to provide the extra energy needed to capture grass ERDP.

“Additional high quality protein is most cost-effectively supplied in the form of dedicated rumen-bypass proteins, like SoyPass and heat-treated rapemeal (ProtoTec), which have been shown to reduce days-to-first-service and days open, and improve pregnancy rate (see table 1). Scottish barley distillers’ feed and bio-ethanol wheat distillers’ feed are also worth considering, as they offer a great combination of both digestible fibre and high quality protein.”

Table 1 – Effect of feeding rumen-bypass supplements on fertility

                                                                                                                                 (Source: McCormick et al., 1999)

Timing is also critical, with intakes highest in the late afternoon and early evening, so bring cows in to buffer feed for 2-3 hours before afternoon milking, then turn them onto the best pasture overnight. If possible, house early lactation cows overnight to maximise buffer feed intakes, as high yielders will generally show the greatest response to buffer feeding.

“Finally, if the weather’s hot like last spring, keep cows indoors in the shade on a buffer feed during the day, and focus on grazing overnight,” Dr Marsden concludes. “Feeding 60-70% of the ration between 8pm and 8am – when it’s cooler – has been shown to successfully increase milk production during hot weather.”

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