Insight Focus

Feeding regimes for dairy cows must suit herd needs and resources. Dry matter intake and metabolizable energy are crucial for body condition, milk yield and overall health. Understanding the cow’s annual cycle helps adjust feeding strategies throughout the year.

As discussed in previous articles, the dairy cow is a ruminant requiring a bulky, feed-based diet to meet all her nutritional needs. Feed is considered the highest cost factor per litre of milk produced by a dairy cow.

It is imperative that the feeding regime considers:

  • The individual dairy enterprise’s resources and facilities.
  • Output objectives, e.g., milk yield and quality.
  • Balanced nutrition for the cows, taking into account breed, calving pattern and output.
  • Optimum rumen function and nutrient absorption.
  • Maximum utilization of home-grown feedstuffs.
  • Financial and other practical considerations.

Understanding Dry Matter Intake (DMI)

Dry matter intake (DMI) is the primary concern when designing a feed ration. Dry matter refers to the amount of feed consumed by the cow, minus its water content.

DMI is calculated based on cow weight and breed. For example, a Holstein Friesian cow can consume 3–4% of her total body weight in DM per day during full lactation. Higher-yielding cows will have a greater ‘voluntary food intake’ and thus consume more than lower-yielding cows.

Energy Drives Cow Performance

As discussed previously, a number of nutrients must be provided to animals for them to function properly and maximize their productivity.

Energy is often the greatest limiting factor in cow performance. The dairy cow requires metabolizable energy (ME) for maintenance, reproduction, lactation and body condition score (BCS).

The Dairy Cow’s Annual Production Cycle

Understanding the cow’s production cycle provides the basis for a feeding strategy and helps explain her differing energy requirements at each stage.

The objective is for the cow’s cycle to birth one calf every 365 days. In reality, this is challenging to achieve across an entire herd, but it remains the goal. Gestation lasts approximately 283 days, though a small variation is normal.

This annual production cycle can be divided into four stages.

Early Lactation (~Day 0-70)

This stage begins once the cow gives birth and milking starts. Milk yield accelerates rapidly during this early stage, peaking around the first 10 weeks post-birth. Nutrition is likely the most limiting factor in reaching maximum potential at this peak, affecting total lactation yield, which can be estimated by multiplying peak daily yield by 200.

During this stage, the cow will experience an energy or nutrient gap, losing weight as her Body Condition Score (BCS) declines due to feed intake being lower than her energy needs for peak milk production. Her body weight and BCS are typically at their lowest at the end of early lactation and into mid-lactation.

Although the cow will be transitioned to a higher-concentrate diet post-calving to limit this energy gap, this must be done gradually. The rumen requires time to adjust. Abrupt changes can cause digestive problems and reduce milk production and BCS. Understanding the principles of ruminant feeding behavior explained is crucial for successful dietary transitions. Careful monitoring of the cow’s response to diet changes is essential, as it helps identify any signs of distress or digestive upset early on. This ensures optimal health and productivity, ultimately leading to improved milk yields and overall herd performance.

Mid Lactation (~Day 70-140)

Ideally, the cow will be impregnated early in this stage to maintain a 365-day calving pattern, either via the use a bull or artificial insemination. Milk yield declines from the early lactation peak, while feed intake and energy consumption reach their peak at the beginning of this stage.

Milk yield will continue to decrease from here, at around 7–8% per month, with feed intake also falling. As total feed intake declines, the ratio of bulky to concentrate feed increases. The aim during mid-lactation is to maintain milk production as high as possible while stabilising body weight and BCS as the young foetus grows.

Late Lactation (~Day 140-305)

As milk production and feed intake continue to decline, this stage of the cow’s cycle is crucial for increasing body weight and BCS. This is to prepare the cow for the dry period during the final stage of gestation, as well for her next lactation. Concentrate levels are adjusted depending on her BCS—either increased to improve or decreased to maintain the desired level.

Dry Period (~Day 305-365)

This final stage prepares the cow for calving and the next lactation cycle. Maintaining an appropriate BCS is essential, avoiding excessive weight gain that could lead to calving complications. Feeding at this stage typically includes low-energy, high-quality forage such as straw.

Achieving the right balance of BCS, energy and rumen function helps optimise calving, reduces mastitis risk and supports milk yield potential, general cow health, welfare and output.