It is well known that the most efficient diets are the most profitable. Maximising feed intake and milk production is thus essential to improve the gross margin of the dairy farm. In fact, a + 0.1 point improvement in the milk index – ratio between the quantity of fat corrected milk + primiparous correction and DMI – leads to an increase of 0.5 euros/cow/day in the margin on feed cost (Techna Research). Feed efficiency is something you need to manage from the beginning to the end of the career of the dairy cow.
Ruminant Nutritionist
Techna Nutrition France
Ruminant Technical Sales Manager
Techna Nutrition UK and Ireland
WHAT IS FEED EFFICIENCY?
The definition of efficiency is a ratio of outputs to inputs. Therefore, feed efficiency is a measure of an animal’s ability to transform ingested feed into metabolically available nutrients for production. A feed efficient animal should eat less whilst maintaining production or eat the same with increasing production. For example, for a 30 L dairy cow, to improve feed efficiency from 1.4 (l/Kg DM) to 1.5 means that we save around 1.4 Kg DM intake/cow/day.
It was long assumed that digestibility was similar across individuals. However, it is now evident that individual cows differ in their ability to digest various feedstuffs. These differences in digestibility among dairy cows is due to many factors such as nutrition (being one of the main focuses), breed (selecting genetically more efficient animals), health of the animal, days in milk, weather, and management etc.
As an industry we can make incremental changes to factors such as management, nutrition and selecting more feed efficient animals which will have a big impact overall on feed efficiency.
In terms of nutrient digestibility and uptake there are two main focuses: Rumen and small intestine.
The rumen is the most well discussed part of the dairy cows’ digestive tract; it is often called the engine of the cow. The rumen’s anaerobic environment and a pH of between 5.8 – 6.8 favours the growth of microbes. These microbes digest or ferment feed within the rumen and make volatile fatty acids (VFAs) which are absorbed through the rumen wall where they can be used as a source of energy by the cow. The major nutrients required by rumen microbes are carbohydrate and protein in which there is a fine balance between the two to meet the microbial requirement. An imbalance can affect the microbial population and have a negative impact on nutrient digestibility, feed efficiency and the production of the dairy cow. Optimal rumen function is crucial for maximising microbial protein synthesis and the quality of the protein reaching the small intestine.
The small intestine is not as widely discussed in dairy cows, however it has a role to play in the digestive process. The small intestine consists of three sections: The duodenum, jejunum and ileum. The small intestine completes most of the digestive process and absorbs many nutrients through villi (small finger-like projections). From the villi the nutrients enter into the blood and lymphatic systems.
RUMEN NUTRITION
Carbohydrates
Carbohydrates are the primary source of energy in the dairy cows’ diets. The majority of carbohydrates are digested in the rumen through microbial fermentation where almost all the digestible carbohydrates are converted to VFA’s (acetic, propionic and butyric acid) and absorbed through the rumen wall as a source of energy. The ratio of acetate, butyrate, and propionate is determined by the source of carbohydrates and the rate of digestion. It is one of the major factors controlling the energy available for microbial growth and consequently the energy and protein available to the cow.
Ruminal fermentation of carbohydrates affects productivity and is a critical consideration for diet formulation.
Protein
Protein is a key nutrient but in deficit (less RDP) or in excess (high RDP) it can have a negative effect on the cow. A lactating cow’s protein requirement is between 14% and 17%, depending on yield. Cows have a greater bypass protein (DUP) requirement as their yield increases.
Within the rumen, the digestion of proteins results in the production of peptides – peptides are further hydrolyzed to amino acids, some of which are deaminated, producing ammonia. Peptides, amino acids, and ammonia all individually serve as sources of N for various microbes. However, problems can occur when there is a high level of RDP present which can accumulate in the rumen. Energy is then needed to excrete excess nitrogen, rather than using energy for milk production.
Feeding the cow a specific blend of essential oils—such as NOVATAN—increases protein use and reduces ammonia emissions. It improves protein efficiency and rebalances protein partitioning—with more bypass and less RDP. Therefore, the cow can utilise protein that would otherwise be wasted and which would be having a negative effect on the cow and on the environment.
Fats and oils
Fats and oils are concentrated sources of energy to the dairy cow where the majority of it is digested in the small intestine. The type and level of fat in the diet influences the milk fat content and fatty acid profile. Also feeding a lot of unsaturated fatty acids can be toxic to rumen bacteria, slow fiber digestion, and lower rumen pH which will negatively impact feed efficiency.
RUMEN HEALTH
Subacute Ruminal Acidosis (SARA)
The rumen should ideally be at pH 6-7. Throughout the day there will be periods when the pH drops below pH 6, but it is for how long it stays below pH 6 that has a negative impact and this is when subacute ruminal acidosis (SARA) occurs. SARA in dairy cows is a common metabolic disease characterised by a prolonged, but not severe, decrease in rumen pH. The decrease in rumen pH can be caused by diets high in readily fermentable carbohydrates and low in fiber.
SARA is associated with decreased fiber degradation, decreased acetate to propionate ratio, and decreased CH4 formation, which can reduce feed intake, milk yields and milk fat. Not only that but it can cause ‘leaky gut’ where the gut wall is compromised and will reduce the efficiency of nutrient absorption and increase the risk of unwanted bacteria and toxins getting into the blood. When bacteria or toxins are absorbed into the blood, this initiates an immune response, which is an energy cost to the animal.
To assess the degree of safety regarding the risk of SARA, a rumen indicator was integrated into the data management tool EASY MAP, considering several parameters such as fat/protein ratio, fat equivalent lactation and fat drop.
In addition, following research in collaboration with the INRA in France, Techna developed a DM4 criteria. This is a measure that can be used to determine the proportion of dry matter that has been degraded after four hours in the rumen—starch, sugars, NDF, pectins, protein and so on. DM4 is a criterion used to predict the risk of acidosis across all major raw materials (Figure 1). Fresh grass—in particular young grass—has a high DM4 value. Anything that has a DM4 of 50% and above is a feed that is putting the rumen at risk of a SARA and acidosis. Ensuring rumen pH is stable and optimal will help keep the rumen in good health. Buffer feeding and/or using feed additives such as yeasts, buffers and essential oils, will help stabilise rumen pH. Rumen buffers act by alkalising the rumen, while a specific blend of essential oils will switch the lactate into propionate—securing rumen pH.
Mycotoxins
Mycotoxins are toxic secondary metabolites produced by certain fungi (molds) that can contaminate feedstuffs like forages and grains. Mycotoxins can negatively impact dairy cows, leading to reduced milk production, decreased feed intake, impaired immune function, and potential health issues; ultimately impacting feed efficiency.
Cows are usually able to manage some level of mycotoxins in their diet but as the load grows so does the risk. It tends to be at times of stress that cows will be affected most but these can be as small as a routine foot trimming or vaccination. By the time you see the effects of mycotoxins, such as swollen hocks, increased temperatures or reduced intakes, milk yield will already have suffered.
To help manage mycotoxins, feed should be stored properly, tested for mycotoxins, and if mycotoxins are present then use feed additives such as VITALPROTECT that help mitigate mycotoxins while maintaining digestive tract integrity.
SMALL INTESTINE
Not all nutrients are fermented in the rumen, a portion escapes fermentation and flows into the small intestine. The small intestine is the absorption centre for many nutrients such as starch and protein. Starch that avoids rumen digestion is broken down and absorbed in the small intestine, providing glucose directly to the cow.
Protein absorbed in the small intestine is delivered as microbial protein from rumen microbes and undegraded protein (RUP). Both microbial and dietary proteins are digested by enzymes, breaking them down into amino acids. These amino acids are then absorbed into the bloodstream for use by the animal and are a significant source of amino acids for the ruminant. The intestinal crypts in particular are the site of intense nutrient absorption and increasing the capacity of absorption is a way to improve feed efficiency (Figure 2). Some feed additives help with increasing the villi size and crypt depth within the small intestine such as essential oils, prebiotics, enzymes, etc.
MONITORING PERFORMANCES
Many factors can contribute to improvements in feed efficiency, but without good monitoring practices then how can the herd’s improvements be known and future goals be achieved? To meet this need, EASY MAP, a decision making tool, collects the herd’s milk data, processes it and provides a detailed analysis of the herd’s performance. The aim is to provide a cutting-edge zootechnical interpretation, by creating various indicators that link feed and zootechnical performance: Milk production, rumen safety, energy coverage and protein efficiency.
Data management tools like EASY MAP allow an insight into what the farm is achieving so that changes can be implemented and future goals to be set.
GOOD MANAGEMENT PRACTICES
It is based on several important levers:
● A good preparation for breeding will improve the efficiency of the feed diet and thus positively improve the reproduction, health, production of the herd, and age at first calving (Figure 3). A calving age between 22-25 months can lead to higher lifetime milk production, improved reproductive health, and reduced rearing costs,
● Ensuring adequate feeding space to prevent bullying, injuries, and stress, which can reduce feed intake,
● Providing adequate lighting in cubicle and roaming areas to stimulate feeding,
● Cows should always have access to clean water, which is extremely important for the production, health and welfare of the cow.
GENETICS
Feed efficiency is one of the most economically important traits and is sufficiently heritable to respond to genetic selection. Currently, selecting for feed efficient traits is done through research and industry settings with special facilities designed for this purpose. This is costly and limits the number of animals measured in the research projects and by cattle breeders. Therefore, progress has been slow. However, as the size of dairy herds increase, automated milking is becoming more and more widespread. Milking robots can help interpret ration efficiency thanks to the various data they can provide instantaneously (feed intake, rumination and milk production).
CONCLUSION
By selecting the right feed components, managing the balance of VFAs through optimising pH, good management practices and data monitoring; dairy farmers can optimise the feed efficiency of their cows for better performance and profitability. With an improvement in feed efficiency less nutrients should be wasted, and it should lead to less land and resources required for feed production. Striving to be as efficient as possible benefits the farm no matter the situation.
Feed efficiency of dairy cows is a crucial objective. At Techna, we remain committed to advancing our knowledge and expertise to enable the industry to become more efficient.
About Alizé Philouze
Alizé Philouze holds an engineering degree in ruminant production from ESA in Angers (France) and has several years’ experience in ruminant nutrition and breeding. She is currently a ruminant nutritionist at TECHNA, where she combines scientific research and practical applications to support ruminant feed manufacturers in France and abroad.About Jamie-Leigh Douglas
With a doctorate in ruminant nutrition from Aberystwyth University, Wales, Douglas has over 10 years expertise in the field. She works closely with feed mills and nutritionists focusing on developing tailored solutions that address balancing zootechnical and environmental performance, animal welfare, economical profitability in the ruminant sector.
