There are at least four possible reasons why a group of first lactation dairy heifers is not developing as well as expected, says Adam Collantine, Dugdale Nutrition’s dairy consultant.
He says: “Every herd has them - a group of heifers which are just not doing what you thought they should.
“This could manifest itself as a heifer which you thought could give up to 35 litres per day, but is maybe only doing 26-28 litres.
“Alternatively, it could be a heifer which still is not in-calf by 200 days, or maybe it just looks in poor condition, hairy and small. There are at least four reasons why this could be the case.”
Mr Collantine says the first reason is the choice of sire, but it is often too late to do anything about this.
“There is no escaping the fact every now and a then a bull will produce heifers which just do not perform within the targets you have set out. Obviously, it is too late for this group but it is certainly a good idea to remove the bull from your sires list, if you have not done so already.
“The second reason is a potential health issue. Heifers are under a lot of pressure in their first lactation. They find themselves suddenly thrown in with a large group of mature stock, getting milked twice a day and are on a different diet to the one they were used to.
“This level of stress can open the door to a large number of diseases and it is worth discussing issues such as liver fluke, lung worm and vaccinations with your vet,” says Mr Collantine.
He says the third and fourth reasons are split by an average of 30 months. The first of these is calf rearing and can even include the way the heifer’s dam was managed while in her transition period.
The way the heifer entered the world has a huge bearing on her lifetime performance. Effective transition management can have a huge impact on performance, by setting part of the animal’s immune function as well as growth rates and vigour.
“Colostrum is the first factor of calf rearing which can impact performance in adult life. Calves fed four litres of colostrum at birth, as opposed to two litres, have been shown to give about 2,500 litres more milk over their first two lactations. This is somewhere in the region of three to four litres of milk per day over this time period.
“The second factor associated to calf rearing which can influence lactation performance is growth rates. Higher growth rates in heifers are often talked about as a way to reduce the average age at first calving, thereby paying back their rearing costs more quickly. However, higher growth rates are also proven to increase lactation performance by somewhere in the region of 600-700 litres in the first and all subsequent lactations. This is probably another two litres of milk per heifer per day,” he says.
“The last of the four reasons which can affect the performance of your heifers in lactation is the way you manage them immediately before they have their first calf. It is generally accepted first lactation heifers do not get milk fevers.
“To some extent this is true; only 1 per cent of these animals will get a clinical case of milk fever. However, we need to be aware as many as 30 per cent of heifers calving for the first time get a sub-clinical milk fever.
“While these animals might not be ‘downer’ cows, and may not even appear unwell at all, the effect of this sub-clinical milk fever is huge. It will make her slower to cleanse, reduce her feed intake and put her at greater risk of ketosis and twisted stomach.
“Just as importantly though, it will hold her back throughout the whole of the first lactation. To combat this, heifers should be treated the same as dry cows for the last couple of months prior to calving,” says Mr Collantine.