At the annual Total Dairy conference, this year held at Kelle University for the first time, an A-class line up of speakers addressed the audience. Laura Bowyer and Ann Hardy report.
Producers feeding dairy heifers on ad lib rations are not only compromising their animals’ feed efficiency but will also incur higher rearing costs than they need. Instead, they should offer a diet which includes high quality forage and restricts access to the feed for a period of the day.
However, if they are unable to offer this ‘limited access’ programme with the precision and quality required in terms of the ration itself and its delivery, they would be better sticking with their existing ad-lib option.
This message was delivered by Jud Heinrichs, Professor of Dairy Science at Penn State University, Pennsylvania, at last month’s Total Dairy Seminar held in Staffordshire.
He said: “If the dairy heifer is eating for 24 hours a day I see her eating cash.”
Instead, he suggested troughs should be empty for at least four hours a day and said a workable system may involve feeding once a day at 9am, pushing up once during the day and having empty troughs by the evening.
“Good managers do it by the clock,” he said, adding it is also essential to have scales to monitor heifers’ progress, to know and precisely meet their feed requirements and growth targets, and to expect to make adjustments in the first couple of months as the system beds in.
“Making a $100 mistake on a heifer is easy,” he warned, suggesting farmers can inadvertently add a month to the US target of 23 months in age at first calving or their cattle could weigh 40kg too little at the time of calving.
However, getting the system right reaped efficiency rewards as intakes were reduced by 10-15 per cent compared with ad-lib access while growth rates stayed the same.
Explaining the physiology behind the recommendation, he said if an ad-lib diet included high quantities of low quality roughage it would require more chewing and its passage through the rumen would be slow, so more energy would be expended in its digestion. This was because the particle size of forage, however long and fibrous, had to be reduced to 1mm or less before it could exit the rumen.
“Indigestible feed, such as straw, stays there a long time,” he said. “It fills up the rumen.”
This inefficiency would be compounded as any concentrate fed with the roughage would tend to pass through the rumen quickly because of its far smaller particle size and the finite space in the rumen, already full of roughage, tending to force it through. This may reduce the concentrate’s digestibility in relation to its theoretical value.
Further inefficiency comes into the system when the total volume of the heifer’s diet is high, as each kilo passing through the gastrointestinal tract has a cost in terms of calories.
“We are changing the way she digests. We are changing the bar.”
However, Prof Heinrichs said precision- or limit-feeding heifers demanded high levels of management and high quality forage.
“If forage quality is poor, limit-feeding may not be a good idea,” he stressed.
Other challenges included having plenty of feed access to allow all heifers to eat at the same time and if this proved difficult, he said feed could be split up, with two-thirds at about 9am and the final third at 11am.
“You should have two hours between feeds. Not one hour and not four hours. In two hours they will consume all they want and the others can eat, but this is only if there is over-crowding and if feed is out for eight to 12 hours a day.”
Saying heifers only tended to eat for three to four hours a day, he said a consistent group in terms of age and size with plenty of feed face access was by far the best option.
If it all came together, Holstein heifers should grow at the optimum 800-900g/day between three months and puberty and should be ready to move to a high roughage diet some six weeks before calving.
“You want to have a normal adjustment to the close-to-calving ration,” he said. “You want her to have a full rumen on calving day.”
Dr Adam Lock of Michigan State University closed the Total Dairy proceedings by addressing what he described as four generations of misconceptions of the health effects of dairy products.
The most recent UK health advice halved the recommended inclusion of dairy products in the daily diet from its previous set of advice.
As a beverage, milk has a similar calorific content as fizzy drinks, but it is rich in essential nutrients, making it one of the most nutritious beverages, he said.
He said: “In recent years, the concept of eating healthy has become synonymous with avoiding fat, but the second most common fatty acid in milk is oleic acid, the same as what is found in olive oil which people have a good perception of.
“The misconception is dairy products lead to long-term blood cholesterol levels, but they contain both good and bad cholesterol and researchers have been found the main source of heart disease is not cholesterol, but instead genetics.
“Non-animal fat sources actually make up the highest proportion of saturated fat consumption in the US.
“You do not die of cholesterol, you die from heart disease. There is no significant evidence of a link between saturated fat, found in milk, and disease. A study shows a higher level of saturated fat derived from dairy can actually lower cardiovascular risk.”
Dr Lock emphasised the need to better promote milk and described how chocolate flavoured milk was being promoted in US high schools as a sports recovery drink as it is better at supplying electrolytes and protein post-workout out than other sports drinks.
He said: “Another common misconception is saturated fats should be replaced by unsaturated fats, but the data does not back this up and by doing so, consumption of sugar and starch is increased.
“We need to keep talking about the health benefits of dairy products as we have four or five generations of negative thinking to reverse.”
UK research shows consuming dairy products gives a ‘survival advantage’ in terms of life threatening disease and it can help supress some cancers, strokes and diabetes.
He said: “The tide is starting to turn on whole milk and studies show low fat milk does not decrease cholesterol levels. There is no evidence low fat dairy products are any better for human health than full fat.”