Feeding a a diet with a high energy density this winter and next spring was highlighted as a way of meeting the herd’s feed requirements while keeping costs at a minimum at the recent Teagasc National Dairy Conference.
Dr. Aisling Claffey, Teagasc dairy specialist, James Dunne and Dr. Kevin Stagg held a workshop at the event, which focused on energy density of the diet and dry matter (DM) intake to support milk production.
The workshop looked into the importance of forage quality and supplementary feed options, while inspecting the value of these in meeting potential feed deficits during the coming winter and spring period.
Dunne told attendees that “energy density of the diet is key” as he mentioned that DM intake, especially in the early lactation, can be a struggle.
Energy density
The message on the day was that “silage needs to be tested, and the best saved for the spring”, as we know that the spring of 2024 saw an increased level of forage feeding than usual due to poor conditions and growth.
So, it is important that decisions taken over the next couple of months to manage forage availability do not compromise the herd performance in early lactation.
Dunne mentioned that “in early lactation, the value of spring grass can not be underestimated” and that the requirements of the dairy cow and the energy supplied by the variety of forages and concentrates need to be understood before utilised.
The UFL availability per kg/DM forages and concentrate feed ingredients are as follows:
Forage and wet feed ingredients UFL / kg DM Concentrate ingredients UFL / kg DM Grazed grass (spring) 1.0-1.1 Barley 1.16 Grazed grass (summer) 0.9-1.0 Maize 1.22 Grass-clover swards 1.0-1.1 Beet pulp 1.14 Grass silage (74% DMD) 0.84 Soya hulls 1.05 Grass silage (68% DMD) 0.76 Palm Kernel 0.93 Maize silage (25% starch) 0.80 Soya 1.18 Brewer’s grain 0.92 Maize distillers 1.16 Eorna / Trafford gold 1.16 Maize gluten 1.04 Fodder beet 1.12 Sunflower 0.66
When you are calculating the energy requirements of the dairy cow, there are a number of components to be considered, including: maintenance; activity level of the animal; milk production; body condition score (BCS) gain or loss; growth requirements and negative association effects (NAE).
The requirements of a 550kg dairy cow producing 25kg of milk in early lactation at 4.3% fat and 3.4% protein on 20% concentrate and 80% forage diet, are as follows:
Component UFL/day Maintenance 6.1 Activity (+15%) 0.90 Milk production 11.5 0.5 BCS loss -1.4 Neg. Assoc. Effects 0.6 Total required 17.7 UFL required from forage 13.8
This tells us that a cow would need to consume 12.5-13kg DM of spring grass to meet her requirements or 16.5kg DM of 74% DMD silage, which is physically impossible due to the cow’s intake capacity, gut fill and passage rate of silage.
Dunne said that “dry matter intake in early lactation is a struggle for the animal” as the table highlights the importance of grazed grass in the diet in the early lactation accompanied with quality forage and increased supplements when pasture is limited.
Dr. Stagg compared two diets in the early lactation in terms of cost and he emphasised “if their milk is not going into the tank, keep them inside and don’t put them under pressure”.
He also mentioned that in early spring, “it is not worth grazing down tight as it only puts heifers under pressure”.
Dr. Stagg said that for allocating grass, “go out once/week and allocate a bit more grass, and if they eat it, that’s now the new allocation”.
Diet one that he compared was a diet of 68% silage DMD with 6kg meal and diet two was the cows out at grass by day and is as follows:
Diet 1
68% DMD + 6kg mealDiet 2
Grass by day Feed cost/day €4.34 €3.68 Value of milk €8.80 €11 Margin €4.46 €7.32
What this table shows, is that getting cows out at grass by day in early spring is worth an extra €2.86 cow/day, which shows the value of spring grass early in the diet.
Winter diet
Over the next eight to 10 weeks should be about manipulating the cow’s diet to have a lower energy requirement and to give yourself a breather in terms of workload.
BCS, forage quality, facilities and workload have to be considered when making decisions around stretching forage over the winter months.
Grouping animals who have a low BCS may have to be done, especially when they have not been allocated enough time at dry off.
By grouping these animals separately, you can give them access to high quality forage or extra meal to ensure they get back on track and have them calving at a BCS of 3.25.
Dunne said that it is important not to overlook the requirements for weanlings and in-calf heifers to also have access to high quality forage and he said that “every farmer should buy a scales, as when it is in the yard, you’ll use it”.
Dunne emphasised this and told attendees that it is essential that heifers and weanlings are reaching their targets and that the best way to do this is by having a scales.
Speaking about once-a-day milking be it in early lactation or before drying off, Dunne said it is crucial that farmers keep feeding the cow at the same level.
Ultimately, the decisions that you are making now in terms of forage allocation and the grouping and feeding of cows and heifers, is going to determine how successful your spring calving period is going to be.