With grass growth starting to pick up many dairy farmers I speak with are considering turnout of cows to grass over the next few days/weeks. While this is a welcome opportunity it does throw up some management challenges.
It is important to note that a dairy cow will reach highest milk yield six to eight weeks post calving but feed intake will not be maximised until 10 to 12 weeks. Intake of grass silage, grazed grass and concentrates will be the key determinant of successful levels of milk solids per cow, performance and profitability; so the diet needs to be balanced accordingly.
Guidelines for Feeding Dairy Cows
The aim should be to achieve between 17-20 kg DM/day with overall protein in the diet of between 16-17%. Spring grass is highly digestible with energy levels of 12.5 MJ/KG DM together with a high sugar content and low fibre levels. Therefore, energy will be the limitation at grass and must be carefully balanced with protein for optimal milk performance. Insufficient energy in the diet of a spring cow can create many problems such as low milk protein, reduced milk yield, poor reproductive performance, more susceptible to diseases and metabolic disorders. In early spring, weather conditions may not be ideal and the estimated intake not accomplished due to low dry matter and low grass covers.
Protein to Improve Cow’s Milk Solids
Insufficient protein in the diet of a spring cow can be caused from over reliance on estimated grass silage quality offered in the diet. It is important to note that grazed grass will be high in protein in early spring and this must be balanced with other components of the diet. When milk protein is below 3.0% in early spring, an energy deficit is most likely the problem. Higher protein feeds will depress protein content in the milk as the cow will need to metabolise excess protein and will also result in reduced body condition score.
Essential Fibre for the Dairy Cow
Insufficient fibre in the diet will also compromise milk fat. This is mainly a problem in early spring due to lush grass being highly digestible. The objective here should be to provide as much palatable fibre sources as possible to slow the rate of digestion, which can be achieved from long fibre forages such as hay and straw. Soya hulls and beet pulp may also be offered but intake must be monitored for successful results. Rumen buffers such as Acid Buf will also help create a better rumen environment to maintain rumen health and function. These rumen buffers are slow releasing sodium bicarbonate which maintains rumen pH, preventing ruminal acidosis and maximising the yield of rumen volatile fatty acids.
The objective is to maximise the quantity of grass in the diet of the fresh calved cow. My advice is to ensure this of high quality and only use high quality concentrate supplements and monitor feed intakes at all times. It is important to ensure supplementation rate is matched to milk yield and body condition of cow. Magnesium is another important part of the diet to prevent grass tetany at grass. A minimum of 56 grams is required per day. Appropriate mineral supplementation should include key trace elements and vitamins such as calcium, magnesium, sodium, manganese, copper, zinc, selenium, iodine, vitamins A, D and E.
Feeding Guide for supplementation at Grass or on Silage
The following table is a useful guide and outlines the requirement for concentrate supplementation based on dairy cow on silage or at grass. For further information please do not hesitate to contact any member of the Connolly’s RED MILLS ruminant team.
Dairy Cow 600kg producing 28 litres of milk fed silage and concentrates
|Silage||65 DMD||70 DMD||75 DMD|
|Concentrates required||7.9 kg||6.95 kg||6 kg|
Dairy Cow 600kg producing 25 litres of milk on grass by day and fed silage at night
|Silage||65 DMD||70 DMD||75 DMD|
|Grass||6 kg DM||6 kg DM||6 kg DM|
|Concentrates||4.4 kg||3.9 kg||3.2 kg|
- animal nutrition
- calving cows
- milk solids