Lifetime Daily Yield can be increased by increasing the milk production per lactation. If dairy cows reach their peak production between 50 and 70 days in milk, it can be assumed that they will reach the maximum production they should reach according to their genetic potential for milk production.

A trial showed that feeding a dairy ration including Selko TMR reduces the negative effects of heating and microbial growth on the quality of a TMR. Cows fed a TMR with Selko TMR included produced 1.4 litres of milk more.

Fermentation reduces feed value and palatability of the dairy ration - Fresh forage contains microbes such as bacteria, yeasts and mould. It is a mixture of beneficial microbes, such as lactic acid forming bacteria and undesired microbes such as clostridia or moulds. Proliferation of microbes in silages initially leads to consumption of the oxygen trapped in the silage. Once all oxygen is consumed, growth of anaerobic lactate forming bacteria decreases the pH of the silage. This acidification results in stability of the silage.

Feed effciency of dairy cows can be used to measure performance, to monitor income over feed costs and to reduce the amount of methane produced per kg of milk. Digestibility of feed has a big impact on feed efficiency. Fibre digestibility can be improved by using hydroxy trace minerals instead of sulphates.

A trial showed that feeding IntelliBond hydroxy trace minerals instead of sulphates improved rumen health, and increased NDF digestibility, production of volatile fatty acids and production of milk in dairy cows, resulting in an increase of feed efficiency.

Values from the 2021 NASEM requirements are presented in tables with daily nutrient requirements, adequate nutrient intake values, absorption coefficients, mineral and vitamin levels required and typical values of basal diets for dairy cows. Major changes were reviewed.

Dr. Bill Weiss explained how the NASEM 2021 recommendations for trace minerals, macro elements, electrolytes, DCAD and vitamins in dairy rations changed and how the relative absorption coefficient for a source of trace mineral should be taken into account.

Compared to hydroxy trace minerals for dairy cattle, suplhate trace minerals are highly soluble and as a result, can have a strong negative impact on palatbility of cattle feed.

Compared to NRC 2001, NASEM 21 recommendations for supplementation of cattle with Co, Cu, Mn, Zn and I changed, trace metal recommendations for Cr, Fe, Mo and Se stayed the same.

Hydroxy trace minerals dissociate mainly in the abomasum, avoiding high concentrations of trace metals in the rumen with a negative impact on rumen flora. As a result, digestibility of fibre and feed efficiency are improved, while maintaining an excellent bioavailability of zinc, copper and manganese to the animal.

The NRC Nutrient Requirements of Dairy Cattle have been replaced by the new NASEM Dairy 2021 Requirements manual which are based on age, weight, reproduction and production stage.

Highly productive dairy cows require an optimal supply of essential trace minerals to maintain a high level of cow health and productivity. Both the level of individual trace minerals that are being formulated into the ration and their form are essential to achieving this objective.

During the EAAP congress, Professor Spears will discuss research that indicates that hydroxy sources of Zn and Cu are metabolized differently in the rumen than sulfate sources. This have an impact on fiber digestibility of dairy cattle.Limited research suggests that trace mineral source may affect the rumen microbiome of dairy cows.

Five important drivers of feed conversion rate and feed efficiency increase profits and sustainability of dairy farms.

Breeding for feed intake capacity reduces the feed efficiency of dairy cattle, but breeding for feed efficiency traits also reduces the feed intake capacity. Efficient dairy cows utilise roughage better for milk production but do not eat more compound feed.

Professor Santos from the Department of Animal Sciences at the University of Florida discusses how to calculate feed efficiency of dairy cows and how it impacts dairy performance. Residual Feed Intake of dairy cows is a very accurate parameter to calculate feed efficiency of dairy cattle. It can be improved by genetic selection, nutritional tools and dairy management.

Dr. Mike Hutjens explains that feed efficency of dairy cows is an important performance indicator to improve sustainability and profitability of dairy farming. Feed efficiency in dairy cows can vary between <1.3 and >2.0. Digestibility of feed is one of the factors with a big impact on feed efficiency of dairy cattle.