Spring is the most challenging period for grazing and feeding the dairy herd. Teagasc has compiled a short review to answer some of the most commonly asked questions about herd nutrition in spring, while keeping firmly focused on utilising more grass to drive financial margins.How much energy, protein and fibre does the cow need in early lactation?
Spring is the most challenging period for grazing and feeding the dairy herd. Teagasc has compiled a short review to answer some of the most commonly asked questions about herd nutrition in spring, while keeping firmly focused on utilising more grass to drive financial margins.
How much energy, protein and fibre does the cow need in early lactation?
Energy is the first limiting factor to production in early lactation. Dairy cows typically require 17-20 UFL daily to meet energy requirements. Fibre (NDF) is crucial for optimal rumen function and milk performance (target 32-36% NDF). The protein of the diet (on a PDI basis) should be around 105g PDI per 1.0 unit UFL of intake. This will translate to a diet of 15.5-17% in crude protein (CP) terms.
What level of dry matter intake is possible in early lactation?
Dry matter intake (DMI) is low after calving but increases steadily by approximately 1kg DM each week in the first four to five weeks, reaching a peak DMI at eight to 10 weeks in lactation. A herd with 25% heifers requires 18kg, plus or minus 1kg DM/cow/day at peak. Prolonged wet weather can result in poorer utilisation of grass, reducing intake. Offering an additional 1-2kg DM of high-quality silage in a restricted/on-off grazing situation can offset this (Figure 1).
What is the nutritional benefit of getting grass into the diet each day?
Spring grass is almost 40% higher in energy and 70% higher in protein than average-quality silage (Table 1); it supports better milk solids yield and minimises body condition score (BCS) reduction. While concentrate feeding also increases energy and protein intake, its inclusion rate in the diet is limited due to the cow’s requirement for NDF from forage, the negative effect of a lower forage-to-concentrate ratio on total diet digestibility, and cost per unit of feed.
What should I do if I am tight on grass or ground conditions prevent grazing?
Front-loading supplementation of silage in the diet has less of an impact on performance in the first six weeks of lactation than if the cows are approaching peak milk production. Utilise on-off grazing when ground conditions deteriorate. Cows can achieve up to 90% of their pasture intake potential in three hours grazing after milking. If excessive poaching occurs, temporary housing with high-quality silage (>74% DMD) and concentrate may be needed. However, ground conditions can recover quite quickly in spring so make grazing the default situation from now on.
What quality of silage is needed for milking cows?
Silage for milking cows should be at least 74% DMD, which makes early lactation feeding very straightforward. Low-quality silage (< 70% DMD) limits intake, reduces milk solids yield and can cause excess BCS reduction. Extra meal feeding will not fully solve the nutritional problem of low-DMD silage.
In farm situations where the only silage available is low DMD and access to grass is limited:
Put grass in the diet at least once per day, even if ground conditions are less than ideal. Cows will eat 5-6kg DM grass in three to four hours which adds energy and protein to the diet.Feed 2kg of a high-fibre straight like hulls or beet pulp in midday where grazing is impossible.Review your silage plan for 2025. A typical spring-calving dairy herd needs more than 50% of its silage at 74% DMD plus. National average in 2024 was 69% – there is much scope to change. What level of meal feeding is optimum? What is the expected response?
Substitution rate is the proportion of forage such as grass or silage displaced by increasing concentrate supplementation. Substitution rate depends on proportion of concentrate, forage quality, and type of supplement. High substitution rates reduce milk response to supplements.
In early lactation, up to 3kg concentrate fed has a relatively minor impact on pasture intake. Increasing concentrate further reduces grass DMI and compromises total diet digestibility, despite increases in total DMI and milk yield.
There is a diminishing financial return as supplement rates increase and milk response declines. Maximising milk yield via concentrate feeding is not an economically optimal approach. Focus on pasture quality and utilisation, and improving milk solids efficiency per kg of pasture consumed.
What level of crude protein should be in the ration?
Where grass can be consistently included in the spring diet, a 14% CP dairy nut is adequate. However, if the farm has a heavy soil profile and cows are routinely housed in the spring period, then a high-energy 16% crude protein concentrate may be more suitable. Where cows remain housed with no access to grass for a prolonged period (more than two weeks) then a higher protein ration is required.
Some cows in the herd are very high yielding: should they be fed extra concentrates?
There is considerable in-herd variation around the average milk solids yield. This is also true for intake capacity, with grazing studies in Moorepark showing a range of 14kg to 23kg DMI/cow for groups offered 18kg DM grass daily.
Cows at higher daily milk solids yield tend to have the highest daily pasture intakes. Therefore, once pasture quality and allowance are appropriate for the group average there is little requirement to differentially manage the higher yielding cows.
How do I prevent negative energy balance? Does it affect subsequent herd fertility?
Negative energy balance (NEB) occurs where energy intake is less than energy required for maintenance and milk. If NEB is too severe then excess body condition score (BCS) loss will occur, with detrimental effects on fertility. Rate of body condition loss in early lactation also depends on BCS at calving and herd genetics.
The ideal BCS profile is calving at 3.25 and minimum 2.75 at breeding. NEB can be minimised by getting grass in to the diet, monitoring residuals (3.5-4 cm in first round), and ensuring grass deficits are met with high-energy feeds.
Where BCS of individual animals is very low pre-breeding (BCS 2.5 or less), consider once a day milking while maintaining a high plane of nutrition.
Milk protein in the bulk tank has dropped to below 3.2%. What is the solution?
Milk protein content is lowest at peak milk production (typically 0.3-0.4% below annual average). Herd-to-herd variation in milk protein is strongly influenced by genetics and forage digestibility. Concentrate feeding rate has a relatively minor effect on milk protein and will not compensate for these factors. Low milk protein relative to genetic merit indicates dietary energy is limiting.
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