Erratic Grass

Grazing can be as erratic as the weather, especially where strict grazing disciplines do not exist.

Take the following grass analysis we have seen over the last few months noting that both oil and crude protein have been all over the place. To put this into perspective all grass is 3-4 weeks of regrowth either after a grazing (typically 3 weeks) round or ready for its next cut of multi cut silage (typically 4 weeks). Samples taken in April & May.

Crude Protein – Typically, we would normally expect to see 22%+ crude protein daily but many samples we have seen have struggled to reach 20% and 3 of the attached samples are below 17%. As a result, spring cakes fed to grazing herds are higher protein than the norm.

Oil – Oil is a main driver behind ME however it has Butterfat implications especially in combination with other dietary fats in higher yielding rations. There is a range of 2.7% to 5.4%, this does not sound much but this is significant in oil terms or a 100% rise between highest and lowest attached.  C16 is used to boost butterfat but can actually be ineffective where fibre digestion is compromised (through excess oil).

Neutral detergent fibre (NDF) – NDF range from 44% (good dietary amount) to 32.4% (high chance of acidosis). The 32.4% NDF is equal to cows back grazing or feeding on silage aftermath after a week of growth. Sodium bicarb, straw, alkali buffers or other fibre sources are one solution.

Sugars – are an important source of energy to partner the protein. In well managed grass it is the combinational effect of fermentable energy (sugars) and fermentable protein (protein/nitrogen content). The range here is from 14.5 to 7.8% another significant difference. In some cases, additional sugars or alternative carbohydrates are required.

ME – Energy is a combination of oils, sugars and digestibility. This represents the smallest range from 11.9 to 12.3ME but as we can see the main source of this energy can vary. The solution here is achieved by resolving above.

In conclusion – This season has seen the biggest range of grass values across the best grazing and silage production time (April & May), a significant result of (1) the winter rainfall, (2) excess winter growth, (3) grazing quality and (4) grass management.  In grazing blocks there was either too much or not enough grass as a result of rainfall.

From a nutritionist perspective it is an absolute nightmare day to day, with varying intakes and a host of potential pit fields even just between fields. The answers can often be diagnosed within a few hours by which time the next issue has arisen. Milk recording data, cow muck, yields, constituents and cow behaviour have never been so important, although particularly in AYR calving herds many of these parameters can be misleading or unrepresentative. Whilst each farm may often have a different underlying issue careful investigation is key.

For further advice on Grass & Diet management, contact Wesley at or your local FCG Office.

Posted in Arable & Crops, Chippenham, Dairy & Forage.