April 2020 Monthly Management

Maintaining Butterfat Levels at Grass; Dock Control in Silage Ground; Grass & Grazing

26 April 2020

Maintaining Butterfat Levels at Grass

Digestive upsets, Sub-Acute Ruminal Acidosis (SARA) and low milk fat are common issues in dairy cows at grass during this time of the year.

Lower milk fat can be due to several reasons. The first being a lack of fibre in the diet. This is often seen during the second-round grazing and short rotations of highly digestible grass being fed. If there is reduced fibre digestion, rumen pH is altered, disrupting the activity of the rumen microflora that produce the precursors of milk fat content. In the vast majority of cases, a prolonged absence of adequate fibre will lead to compromised rumen health and performance. Ultimately this will result in a reduction of milk butterfat percentage.

A second key factor for the occurrence of milk fat depression is an elevated intake of unsaturated fats from young, leafy grass. Unsaturated fats are toxic to rumen microflora and in order to survive, they carry out a process call “biohydrogenation”. This process produces by-products (saturated fatty acids) that in effect switches off the mammary gland from producing butterfat and thus milk fat depression arises. This effect can be exacerbated in the presence of a low rumen pH or if rumen health is poor (fibre availability, feed intakes, etc..).

Assessing the physical characteristics of the herd such as manure consistency is a simple indicator of rumen function. Dung stools should not be loose or watery but consistent like soft porridge.

Loose dung indicating poor rumen function. Severe cases will show bubbling and feed particles passed undigested
Loose dung indicating poor rumen function. Severe cases will show bubbling and feed particles passed undigested
Ideal dung consistency indicating healthy rumen function. 5-6 folds (soft porridge appearance).
Ideal dung consistency indicating healthy rumen function. 5-6 folds (soft porridge appearance).

Aside from butterfat depression, low rumen pH may also result in other significant consequences for the cow. Sub- Acute Ruminal Acidosis (SARA) is a common issue and can be addressed quite easily on-farm. SARA modifies rumen fermentation and less substrate for milk fat synthesis is available. SARA can also affect feed intake and impact on milk protein, yield and fertility. The way grass is managed and fed makes it a highly variable feed for cows. From a grass management point of view the following present increased risk of SARA: new pastures vs old pastures, changes in rotation (1st to 2nd to 3rd), dry matter of grass - wet lush grass is more problematic than dry grass. In addition, the management of grass can increase the risk of SARA. For example, under allocation of grass or grazing light covers that do not have adequate fibre content. Offering hay or straw can help provide some fibre in these scenarios.

Milk Fat Percentage

Super Graze plus Rumbuff & Yeast

Super Graze is a 15% diet with a high inclusion of maize. It is almost a necessity to have a buffer included in your feed to counter some of the issues discussed in this article. This complimentary feed has Rumbuff and a live yeast as essential ingredients of the formulation. Rumbuff is a unique blend of slow release buffers that neutralise acid and does not change rumen pH. Because of this, rumen pH is maintained in the optimum range for longer periods. The added live yeast promotes rumen stability and digestion of fibre without disruption. Keeping the rumen function properly is key to feed intake, milk yield and optimising milk composition, particularly milk fat. Fertility booster mineral and Cal-Mag are included, balanced for 3kg feeding rates. Contact Sales representatives or Drinagh Mill for more information.

Dock Control in Silage Ground

Docks are a major, persistent weed problem on many farms. Without adequate control, these weeds will seriously limit grassland output and productivity.
In first cut silage, even a moderate infestation of docks will cut dry matter yields by at least one tonne/acre and significantly impair quality. In baled silage, dock stems play havoc with the film, leading to substantial wastage. With many crops closed for first cut silage at this stage, there is now a real opportunity to plan an application of a proven herbicide like DoxstarPro and eliminate docks before the silage is cut. This product has the right combination of active ingredients and mode of action that ensures a complete kill of the root system, ensuring effective, long term control.

General Dock Control:

  • Apply the herbicide onto actively growing plants 15-25cm (6-10 inches) high or across. This is called the rosette stage and it is here where nutrients are actively transported throughout the roots and foliage. As a result, greater chemical absorption is achieved.
  • Apply at a rate of 2 litres/ha as a single application or two applications of 1 litre/ha 6-12 months apart.
  • If seed stalks are seen on the plant or if the dock has diseased leaves, it is better to wait for re- growth of the docks to ensure proper control.
  • Allow adequate time between spraying and cutting silage for the herbicide to work, especially where weeds have a developed taproot.
  • Avoid spraying in very dry or cold conditions.
  • Remember to keep the prescribed cross-
    compliance records and follow the product label.

Before treatment

After treatment

Effective weed control illustrated in the pictures of the same silage field which had a heavy dock infestation. The picture above, taken a month after treatment, shows a completely dock-free sward.

Grass & Grazing

Grass and Grazing is a new section of the management notes where the grazing situation from a different Drinagh milk producer will be profiled each month.

William O'Donovan
This month’s feature is from William O’Donovan, Minanes, Drinagh.
Date 16/04/2020
Average farm cover 720 kg/ha
Yield (litres/cow) 26L
Fat% 4.20%
Protein % 3.69%
Kgs Milk Solids / cow 2.1
Supplement fed(kg/cow) 2 -3kg
Pre-grazing covers 1400-1500
Days grass ahead 14 days

Growth recorded for last week was 45kg per day.

Transitioning into the 2nd round: Started the 2nd round on the 9th April – currently mixing grazings between the first paddocks on the second round and the last paddocks to be grazed on the first round. This helps cows to adjust from a higher fibre first round grass to lusher leafy second round grass.

Fertiliser: Currently following cows with either 2 bags per acre of 18-6-12 + sulphur or 1 bag per acre of protected urea + sulphur (38N + 6S). The choice between 18-6-12 or protected urea is based on what was applied in the March fertilizer application.