Dairy farmers are continually striving to find ways to improve profitability, as they are permanently facing ?challenges like changes in feed and milk prices. Consequently, increasing income by means of feed costs has become a popular benchmark within the dairy industry.
Efficiency of nutrient utilisation represents a major tool affecting profitability in modern dairy farms. The fact that feed costs account for 70-80% of the variable costs of milk production, show yet again the importance of enhancing the feed efficiency in dairy cows in order to increase profitability.
Next to reproduction and longevity, feed efficiency represents a key driver in high yielding dairy cows. In general, feed efficiency (FE) is determined by cost per unit of gain, in case of dairy cows it is the kg of milk produced per kg of dry matter consumed. It is a measure to determine the ability of cows to turn feed nutrients into milk, respectively milk components.
As the energy amount of milk varies due to fat and protein content, the simple measure – produced kg milk per kg of consumed dry matter (DM), optimal ranging from 1.4 to 1.9 – is energy-corrected (Tyrell and Reid, 1965) to a formula as follows:
ECM (kg) = 0.327 x Milk production (kg) + 12.95 x Fat (kg) + 7.65 x Protein (kg)
Feed Efficiency: Energy-corrected milk quantity (ECM) in kg/ dry matter intake (DMI) in kg
Defining FE in lactating animals is more difficult than for growing animals in their linear phase, as dairy cows show stages of rapid catabolism post-calving, followed by anabolism of reserves until their next calving. Feed efficiency of 1.5 to 1.6 is a reasonable target for cows or herds between 150 to 200 days in milk (DIM). For cows being in milk for more than 250 days, a FE below 1.4 should be expected. Yet a very low FE (below 1.2) in early lactation, could indicate health problems such as acidosis or, if the cow is in good health, a very poorly performing animal. Ultimately there are two ways to improve FE. On the one hand it is to increase milk yield while keeping the same dry matter intake, on the other hand it is to decrease dry matter intake and maintain the same milk yield.
While pigs need to consume 3 kg of feed, poultry 2 kg and fish only 1 kg to produce 1 kg of meat, beef cattle needs 6-8 kg of DMI. FE even varies within one animal species, as younger animals have the highest FE due to their growing and the fact, that they turn most of their energy intake into their growth. Ruminants however, show a rather low FE which is related to their digestive system. Unlike monogastrics, which focus on enzymatic digestion, ruminants show big microbial fermentation processes in their rumen before nutrients are absorbed. In the rumen, a complete microbial ecosystem has evolved and is specialised on the fermentation of roughage, especially fibre. The huge ‘fermentation chamber’ is able to digest fibre, to turn non-protein nitrogen (NPN) into highly valuable amino acids, to produce B vitamins and to detoxify the organism. However, the maintenance of this sophisticated ecosystem is rather expensive, as the first nutrients being available from ruminal fermentation are required to supply the located microbials. More than 50% of the feed is used for maintenance, explaining the difficulties of feed selection in regard to feed efficiency, compared to pigs, poultry or fish.
Several factors in feed management can affect FE, like acidosis (e.g. due to short particle size of forage), high levels of feed intake, or a lack of ruminal degradable protein (RDP) that may lead to a poorer digestibility. As in ruminants the digestion of fibre is of great importance, it goes without saying that high quality forage will raise the availability of energy from the ration. Protein efficiency of a diet is very closely linked to FE, hence a poor level of protein in diets could result in poor FE. A lack of ruminal degradable protein will affect the production of microbial protein negatively and thus, will depress fibre digestibility. Contrary, excessive protein supply may cause increased protein losses and may affect health and fertility. So to optimise FE, the rumen needs to be provided with a certain amount of protein, respectively nitrogen sources on the one hand, and sufficient energy (with a good balance between fermentable organic matter and structural carbohydrates) on the other hand. Moreover, a sufficient supply with minerals and vitamins and best water quality do also contribute to improved ruminal fermentation.
The protein efficiency in dairy cows is very low, e.g. a cow, producing 32l of milk per day (3.3% crude protein) requires an amount of about 3.5 kg dietary protein. This means that only less than 30% of the dietary protein are used for the production of milk protein. The losses run up to more than 70%, resulting from urea content in the urine due to ammonia excess in rumen, indigestible and endogenous excretion in faeces and urine and excretion via urine due to an inefficient utilisation of absorbed protein for maintenance and for the synthesis of milk and body protein.
In the rumen, NH3 is produced via deamination of amino acids or non-protein compounds (e.g. urea and amides). NH3 may be used for microbial growth, provided that energy is available. It may also escape at the lower gastrointestinal tract or be absorbed through the rumen wall and transferred to the blood and liver. In the liver, ammonia is transformed to urea, which is either transferred back to the rumen through saliva and the rumen wall, or it is excreted in the urine. The urea content in milk represents an important tool in monitoring the cow´s nutritional condition. As “waste” of the protein metabolism, it enables conclusions regarding the protein and energy supply of the animal. Milk urea functions as benchmark for the utilisation of dietary crude protein, as it is determined by the crude protein per animal per day, the by-pass protein content, the balance between degradable protein and fermentable carbohydrates in the rumen and the daily milk production per animal.
There is evidence that feed additives generally are able to increase FE, as they positively affect fibre digestion, on condition of high quality forage. Especially plant-derived products are highly accepted by consumers, meeting the growing demand for antibiotic-free diets and livestock being kept and fed appropriate to their requirements and though allowing profitable farming on the other side. Feed additives have been able to substantially up-value ruminant rations for years. Delacon, a family run company located in Austria, has been successfully dedicated to phytogenic feed additives (PFA) for more than two decades, and has emerged from a pioneer in a niche market to a global leader in the mainstream. Delacon has developed a range of phytogenic feed additives* that solely contains natural substances which are carefully selected and tested for optimum effects on efficiency without leaving residues in meat or milk. By improved performance (up to 7-10% without matrix), reduced feed costs (up to 5-10% with matrix), reduction of emissions (e.g. NH3, CH4), improved digestive health and improvement of fertility, somatic cell count and lameness disease. In trials, the effects included: increased level of rumen degradable protein hence improving the metabolisable protein level, improved microbial protein synthesis and the general protein metabolism, reduced NH3 losses and improved protein digestibility in the small intestine.
To measure and prove the effects of these phytogenic additives on the animals´ performance, trials in different countries, with different breeds, different stages of lactation and different kinds of diets were conducted. Results showed an average increased milk production of about 2 litres per day (Figure 1). It was also tested in a scientific trial in Paris Grignon (INRA-PG), including a diet optimisation to decrease the nutrient levels (protein) and thus, the feed costs. In this trial, the phytogenic feed additive proved to reduce milk urea (losses) without having an impact on milk yield and milk composition (Table 1). Efficiency improvements reduce the amounts of feed required for optimal performance of animals and thus affecting feed costs positively. The use of phytogenic feed additives like Actifor® represents a relevant strategy in ruminant nutrition, as apart from their efficacy and their proven beneficial effects on efficiency, digestibility, animal health (metabolic diseases) and undesired environmental losses (e.g. nitrogen, methane), they are natural and safe.
Challenges regarding profitable dairy production emphasise the importance of nutritional expertise and optimum feeding management, allowing livestock to fully meet their genetic potential. Concentrating on feed efficiency in dairy cows is very important to optimise the exploitation of dry matter intake hence to achieve better margins in milk production over the long-term. High quality phytogenic products, containing essential oils, herbs and spices, and supplemented to animals´ rations, have shown to support feed efficiency in a natural though proven way. They do not only contribute to optimal performance and profitability, but also being the best choice for the reduction of emissions in animal husbandry. Therefore, and due to their high acceptance by consumers, they are foreseen to have a great future in livestock nutrition whilst contributing to safe animal derived products.