Implications of poor quality grass on milk decline

Some herds are maintaining milk yield very well through maintaining grass quality and supplementing when needed to balance the grass available and meet the cow’s total requirements. 

With peak milk production behind us, focusing on grass quality over the next few weeks will boost milk protein and overall performance.

Teagasc research showed that cows grazing a cover of 2,000kg DM/ha and required 6kg/head/day of concentrates to produce 23.7kg of milk while cows receiving no concentrates and grazing 1,400kg DM/ha covers produced similar yields of 23.9kg.

Even if peak production was lower than usual, you can still improve outcomes by minimizing the weekly milk volume decline to below 2.5% and increasing milk protein levels. If milk yield drops more than the expected 2.5% per week, the cumulative effect can significantly impact the entire lactation period. For instance, losing an additional litre of milk in mid-June beyond the expected decline could cost a 100-cow herd over €5,500 at current milk prices. Such losses often occur after wet periods, or when cows graze on high covers or poor-quality grass. These drops also affect milk protein levels which are not included in the loss in returns.

Monitor milk decline:

To monitor milk decline:
1. Compare the bulk milk tank volumes of a two-day collection to the previous week's two-day collection.
2. Estimate the difference in milk volume and calculate the percentage reduction.

How to manage decline:

1.Measure Grass Quality: Regularly measure grass to make informed timely decisions about grass management and feeding.

2.Target Covers: Aim for pre-grazing covers of 1,200-1,400 kg DM/ha. Covers above or below this range can limit intake, animal performance, and regrowth. If grass growth exceeds demand, consider making high-quality bales from paddocks with high covers.

3.Intake Requirements: Ensure cows get 18-23 kg of dry matter per day. To maximise intakes allocations need to be 10% higher than the expected intake. For example, intakes of 16 kg DM requires an allocation of 18 kg DM.

4.Supplementation: At this time of year, the milk potential of good quality grass is 20-22 kg of milk. If cows are yielding more than the grass can support some concentrate feeding will be required. If grass availability is low, bridge the gap with increased supplementation. For gaps greater than 6kg/head/day, consider buffer feeding with high-quality dry matter forage.

By focusing on these strategies, you can help maintain milk yields and protein levels, ensuring the health and productivity of your herd.

First Published 11 June 2024