How optimising the rumen can improve dairy cow performance

Published Monday, 2nd January 2017
irwin case study

The Redhouse Holstein herd at Barrycreevy near Benburb in County Tyrone is managed by Alan and David Irwin. With 10 cows already attaining 100 tonnes of milk, the father and son partnership’s over-riding goal is to maintain productivity and fertility by focusing on cow nutrition and rumen health.

Alan and David Irwin farm approximately 240 acres near Barrycreevy where the Redhouse Holstein herd has been housed since 1979. The herd’s 180 cows are milked three times a day and are currently producing a rolling 305-day average in excess of 12,500 litres per cow at 3.85% butterfat and 3.20% protein.

Despite achieving some of the highest milk yields in the UK – the Irwins recently received the High Yield Herd Award in the 2014 Cream Awards – the herd is not pushed to the extremes of its ability.

“With the right feeding and herd management regime, it would be possible for our herd to average more than 15,000 litres per lactation,” David Irwin explains. “But that would be detrimental to cow health, fertility and longevity. Instead, we feed the cows to produce 12,500 litres in the knowledge that at that level we can comfortably maintain fertility and an AI first service conception rate of 50% or more.”

Nutrition critical to success 

Key to the herd’s productivity is the dietary composition and accuracy to which each group of cows is fed: the herd consists of five main groups of cows, each of which is fed a TMR ration consisting of varying amounts of grass silage, wheat straw, home-grown cereals and bought-in concentrates according to their needs and the latest silage analysis report.

“Attention to detail at all stages of a dairy cow’s life is essential,” David continues. “From calves through to mature cows, the diet that each animal receives is carefully calculated. We run the herd as five distinct groups: high and mid yielders, near and far-off dry cows and heifers, and have worked closely with dairy nutritionist Steve Swales to compile appropriate diets for each group.”

The Irwins make three cuts of grass silage from 120 acres and grow 50 acres of spring barley which is fed as whole grain.

“We can grow grass silage consistently year after year although the amount we can produce is limited by land availability,” David adds. “There simply isn’t any additional land locally so we make the best use of what we have got. The farm is too far north to grow a reliable maize crop, so we supplement the grass silage and home-grown cereals by feeding a high concentrate ration with plenty of wheat straw to aid rumen function.”

To ensure each group of cows is receiving the correct dietary intake, the farm’s grass silage is analysed on a monthly basis for dry matter, fibre, energy value, protein content and fermentation characteristics. Each group’s ration is then amended accordingly to compensate for any loss or gain in silage quality, 

“As well as testing for the factors which affect silage palatability and nutritional value, we also assess the lag time of each batch of silage by passing it through an artificial rumen,” David continues to explain.

“Because we feed a high volume of concentrates, we add extra wheat straw to keep the feed in the cows for longer. That means we are able to feed less protein and are currently only giving 16% protein compared to over 22% ten years ago.

David’s attention to detail also extends to the minerals that each of the herd’s rations contains. “Feeding high yielding and hard working dairy cows entails much more than simply filling them with energy and protein,” he explains. “ Maintaining optimal rumen performance not only impacts on milk production in the current lactation, but also dictates a cow’s ability to conceive and maintain condition throughout her next pregnancy. For that reason we use Acid Buf, a sea-algae based rumen conditioner, to promote and protect rumen health and to prevent the onset of Sub Acute Ruminal Acidosis (SARA) and acidosis.

Rumen conditioning 

The Irwins have been using Acid Buf for as long as Alan can remember; “We trust it to keep the cows in top condition and feel that substituting for a lesser product simply wouldn’t be worth the risk in terms of reduced productivity, cow health and fertility.”

The diets formulated by Steve Swales recommend that the high and mid-yielding cows receive limestone and bicarbonate as part of their TMR ration. “We substitute both of those ingredients with Acid Buf as it is a much more efficient rumen conditioner,” David describes.

The inclusion of Acid Buf into the TMR rations has two main benefits for the cows: it prevents acidosis by buffering excess stomach acid, and provides a bio-available source of calcium and magnesium .

Acid Buf has a number of additional advantages over regular sodium bicarbonate according to Derek McIlmoyle, Technical Director for AB Vista who distribute Acid Buf in Ireland.

“Compared to standard buffers such as sodium bicarbonate, Acid Buf has a much higher acid neutralizing capacity,” he explains. “That’s because bicarbonate passes through the rumen too quickly and will typically only buffer stomach acid for a couple of hours post feeding. Acid Buf has a unique honeycomb structure which gives it a longer release period, meaning it is still effective up to eight hours after ingestion. It is also less soluble than bicarbonate, which means it isn’t neutralized when mixed with wet silage and is therefore still effective when the cow feeds.”

Mr McIlmoyle also explains that Acid Buf is economically advantageous compared to sodium bicarbonate. “Although Acid Buf is more expensive per kilo compared to standard bicarbonate, it is considerably more effective. For that reason, less Acid Buf in needed in the diet, saving money and creating dietary space in the rumen.

“Acid Buf can also be used in transition cow rations when cows are either lacking calcium or need extra calcium when a DCAB ration is fed,” Derek continues. “With a non DCAB transition ration it is normal to limit calcium intake so that cows naturally start to mobilize calcium from the skeleton in the run up to calving. However, in situations where the dairy ration has a large maize silage component and a smaller grass silage fraction, there is a risk that the dietary intake of calcium will be below requirements. Acid Buf counteracts this by providing a bio-available source of calcium (and magnesium) and is therefore a useful mineral supplement in its own right.”

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