Introduction

The agricultural industry is finding it increasingly difficult to ensure consistent production of high quality food at a national and global level as a result of a number of challenges. Volatile markets struggle to satisfy growing demand for quality food under economic, regulatory, climate change and environmental pressures. The role of new and existing technologies in the sustainable and efficient production of food will be vital in order to react to continuing market instability. We need to make full use of the resources and technologies available to us in order to rise to the challenge of breeding high quality food to provide for a hungry world.

Optimum milk yields, excellent fertility and better health and longevity are the objectives for every successful dairy farmer. In order to reach these goals, it is clear that good quality, balanced nutrition at every stage of cow management is key. Recent developments in cattle nutrition and advances in routine analysis are enabling us to investigate in greater detail the effects of different diets not only on milk production but on business-critical parameters such as dairy cow health and fertility.

The fundamental challenge posed by this paper seeks to determine whether a healthy diet for cows can provide benefits not only to the cow, but to the farmer, consumers of dairy products and the environment as well.

Changes to the way we feed our cows

High quality grass contains many beneficial nutritional components which can improve the production, health and fertility of dairy cows; these components are often high in protein, vitamins, digestible fibre and oil content – in particular poly-unsaturated fatty acids like Omega-3.

Traditionally, cows would have consumed a large proportion of their nutrients in the form of grazed grass in the Spring and Summer and grass silage in the Autumn and Winter. However, with the push for increased milk yields, we have observed many dairy cow diets using mixed forages as well as increasing the proportions of starch-based feeds such as maize (which are lower in Omega-3 fatty acids and higher in Omega-6 fatty acids). This has reduced the amount of grass and conserved grass included in dairy rations and has seen some cows housed for longer periods of time, or all year round in some cases. Cows are therefore receiving less of these beneficial, naturally-occurring Omega-3 fatty acids, negatively impacting on factors such as production, health and fertility. In the past, finding a way to replace the fatty acids has had adverse effects on milk production and quality. Yet, with recent developments in nutrition and analytical techniques, solutions now exist to manipulate these parameters in such a way that they can benefit not only the cow, but the farmer, the consumer and the environment as well.

Milk fatty acid analysis

Until fairly recently, the primary method for analysing fatty acids in milk was through gas chromatography, an accurate but time consuming and relatively expensive analytical technique.

Developments in technology, in the form of mid infra-red spectroscopy (or mIR), has enabled us to analyse milk fatty acids at a fraction of the cost and with a much quicker turnaround time for results (up to 500 samples/hour). Milk recording laboratories routinely use mIR spectra for butterfat and protein percentage measurements. Soyeurt et al., (2006) concluded that mIR offers the possibility of assessing and improving the quality of milk produced enabling the fatty acid composition in milk to be estimated.

Recent advances in milk fatty acid analysis may help to provide farmers with an unobtrusive measure of feed efficiency and could even be extrapolated to determine methane emissions per litre of milk produced. The production of saturated fatty acids (SFA) has an energy cost to the cow. Thus, reducing the SFA in milk directly benefits the cow and results in milk with lower SFA content which has potential human health benefits. This is a relatively new area although interest is building on a global scale.

BOCM PAULS are currently using bulk milk samples to determine the efficiency of energy use, efficiency of protein use, efficiency of fibre use, risk of acidosis and herd health and fertility using an analysis tool known as ‘Visiolac’. This allows us to see how efficiently the diet is working at herd level and identifies key factors that may be limiting feed efficiency.

Working with a number of organisations within GB and across Europe, the dairy industry is involved in a number of projects investigating the fatty acid analysis of milk via mIR and the implications for dairy cow management and overall performance. The benefit of this technology is not only in improving the methodology to increase the credibility of results but moreover, the ability to interpret the data in order to make meaningful management decisions based on the results observed.

Essential fatty acids

A balanced approach to dairy nutrition offers the healthiest and most efficient way of feeding the modern dairy cow. The correct balance of essential fatty acids can significantly improve production, health and fertility. Unfortunately, essential fatty acids cannot be synthesised by the cow and therefore have to be added directly to the diet. The most common examples are linoleic acid (C18:2, an Omega-6 fatty acid) and α-linolenic acid (C18:3, an Omega-3 fatty acid), which cannot be synthesised by mammals and are classified as essential fatty acids because they must be provided in the diet. These fatty acids are precursors of prostaglandins and eicosanoids, which carry out a wide variety of actions within the cow, and are required for normal growth, reproduction and health. Linoleic acid (Omega-6) is most commonly found in sunflower oil and soyabean meal and α-linolenic acid (Omega-3) in linseed and green forages such as spring grass.

An under-supply of Omega-3 and an over-supply of Omega-6 can lead to a reduction in production, health and fertility because they compete for many of the same enzymes involved in important metabolic pathways in the cow. It is widely recognised within the farming community that forage can provide an important yet somewhat variable inclusion in dairy rations. With the unpredictability of weather conditions, making excellent quality forage, of consistent nutritional performance is a constant challenge. Forages can be extremely variable, therefore any assistance in the form of dietary additives that help to provide consistency to a diet can only serve to help the dairy cow meet the necessary dietary requirements.

Dietary supplementation

Lintec

Feeding dairy cows with linseed in a variety of forms is not a new concept and has formed part of ruminant diets for many years. Lintec is a natural, concentrated source of Omega-3 and can be added into a compound feed, blend or straight offering complete flexibility for any feeding system. It provides an effective way of achieving higher levels of Omega 3 fatty acids in dairy cow diets ensuring that the cows get what they need at the most important times i.e. during early lactation and leading up to, and at, breeding. It also allows farmers to adjust feeding rates in order to compensate for other feeds that may be lower in Omega-3 or for cows in mid or late lactation (where the requirement is reduced).

Unlike other linseed products, the unique and patented thermo-extrusion process used to produce Lintec liberates more of the natural nutrients from linseed making them more available to the cow.

In dairy cows, dietary fatty acids have a well-documented, beneficial influence on ovarian follicular growth, corpus luteum function and progesterone production in dairy cows. Supplementation with Lintec has reported more intense bulling activity in the form of longer and stronger displays of heat (oestrus) (Figure 1, Zachut et al., 2011), stronger recognition of pregnancy, decreased embryonic mortality due to decreased production of prostaglandin, reduced body condition score loss post-calving and improved pregnancy rates.

Appreciating the recent challenges that have been experienced on most dairy farms across the UK, reducing the environmental impact of agriculture may not be front of mind. However, Lintec can also provide environmental benefits too, by reducing the amount of methane a cow produces (Chilliard et al., 2009). Energy losses associated with methane emissions range from 4 –12% of a dairy cows’ gross energy intake. Production of methane in the rumen or saturated fatty acids in the udder provides an energy cost to the cow. Reducing methane production enables the cow to use this energy for other essential functions such as milk production or getting back in calf, providing a significant benefit to the cow AND the farmer!

Lintec has also been shown to decrease acid loading in the rumen by increasing the rate of passage of volatile fatty acids out of the rumen reducing the drop in rumen pH often caused by an excessive build-up of these fermentation products.

Ensuring a consistent supply of Omega-3 can be challenging, especially given the variable climatic conditions we seem to be continually faced with. As we all know, grazing and grass silage varies considerably with season and maturity but using targeted dietary supplementation can help to provide consistency in the ration, whether that be in terms of additional feeding at grass or incorporation into a partial or total mixed ration.

Essential oils

The medicinal properties of plants have been explored for many years. It is now thought that plant-based additives, in the form of essential oils (EO), may enhance rumen function (improve energy efficiency and protein utilisation in the rumen) and improve production performance in dairy cows via the manipulation of the microbial population. Some examples of EO are allicin from garlic, eugenol from cloves, pinene from Juniper, capsaicin from hot peppers, thymol from thyme and oregano, and cinnamaldehyde from cinnamon. Essential oils are the products of secondary metabolism (that seem to have no direct function for growth and development) and some exhibit antimicrobial activities against bacteria, yeast and moulds.

It is thought that essential oils impact the rumen by inhibiting deamination and methanogenesis, resulting in lower rumen ammonia, methane and acetate production, which increases propionate and butyrate production. Given that the effects of EO are diet and pH dependent, the selection of the appropriate EO must be targeted to specific objectives. Moreover, because EO may act at different levels in the energy and protein metabolic pathways, their careful selection and combination may provide a useful tool to effectively manipulate rumen microbial fermentation (Calsamiglia et al., 2007). Essential oils certainly hold promise as feed additives in ruminant nutrition to improve feed efficiency and control the spread of pathogens in livestock. However, identification of EO, or their active components, that positively alter fermentation without resulting in inhibition of rumen fermentation, continues to be a major challenge for researchers and practicing nutritionists alike (Benchaar et al., 2008).

Fungal feed additives

The use of dietary enzymes in poultry, and to a lesser extent pig diets, is now well established. The use of enzymes in ruminant diets is less well accepted and is fraught with legislation restrictions.

Research has demonstrated that supplementing ruminant diets with fibre degrading enzymes has significant potential to improve feed utilisation and animal performance.

Ruminant feed enzyme additives, particularly xylanases and cellulases, are concentrated extracts resulting from bacterial or fungal fermentations that have specific enzymatic activities. Enhancing animal performance due to the use of enzyme additives can be attributed mainly to improvements in fibre digestion in the rumen resulting in increased digestible energy intake. Animal responses are reported to be greatest when fibre digestion is compromised and when energy is the limiting nutrient in the diet although responses to feed enzymes are variable. Some of this variation can be attributed to experimental conditions in which energy is not the limiting nutrient, as well as to the activities and characteristics of the enzymes supplied and inappropriate method of providing the enzyme product to the animal (Beauchemin et al., 2003).

There is general agreement that increases in productivity occur when fungal feed additives are added to the diet resulting from their action in the rumen, and more specifically an increase in the number and activity of bacteria (Newbold., 1997). Feedstuffs that retain residual enzyme activity provided in dairy cow rations enable the cow to get more from the same, or the same from less. This could be in terms of nutrient utilisation or the ability to break down more of the material that is present than would have otherwise been possible. Although a great deal of progress has been made in recent years in advancing enzyme technology for ruminants, considerable research is still required. With increasing consumer concern and legislation surrounding the use of growth promoters and antibiotics in livestock production, along with the potential magnitude of increased animal performance, there is no doubt that feed enzymes, in some form or another, will play an increasingly important role in the future (Beauchemin et al., 2003).

Feed efficiency

As many farmers are looking to reduce costs of production and adopt more simplified and/or flexible farming systems, a targeted and consistent approach to dairy cow feeding could provide us with the greatest return for our investment.

Feed represents the single largest variable cost on farm. Therefore, ensuring that every kilogramme of dry matter consumed is converted into kilogrammes of milk production, improved milk quality or daily liveweight gains are imperative to the success of any farming enterprise.

Figure 2 supports the theory that higher levels of saturated fatty acids (SFA) in milk prove an energy cost to the cow. As a result, reducing the level of saturated fat (in this case palmitic acid, C16:0, the most abundant SFA in milk) benefits the cow and the farmer in terms of enhancing production efficiency and provides a secondary benefit in terms of higher quality milk.

Milk processing and retail

It is possible to target supplemental feeding of dairy cows to influence the fatty acid profile and therefore alter the nutritional quality of milk and dairy products. Currently, the adoption of nutritional practices in reducing the saturated fatty acid content, or altering the composition of milk in other ways, by farmers, processors and retailers has not been widespread. However, this concept may see more extensive implementation with greater consumer demand.

Conclusion

Providing dairy cows with a healthy diet leads to many benefits, including improved health, fertility, production and milk quality. All of the parameters mentioned previously will help to increase the profitability of farming businesses, improve efficiency of milk production and deliver tangible results to farmers.

In order for dairy farmers to look beyond the milking parlour they need to maximise their efficiency, thereby boosting their profitability and ensuring they are sustainable for the future. By considering more than the simple need for energy, mega Joules, or protein and instead looking at the total requirements of the cow, we can enhance animal health, fertility and efficiency. It is a win-win scenario offering benefits to the cow, farmer and consumer. Nutritional innovations and developments in technology ensure that GB agriculture will continue to breed high quality, healthy food to provide for a hungry world.

References

Beauchemin, K.A., Colombatto, D., Morgavi, D.P. and Yang, W.Z. (2003). Use of exogenous fibrolytic enzymes to improve feed utilisation by ruminants. Journal of Animal Science 81: E37–E47.

Benchaar, C., Calsamiglia, S., Chaves, A.V., Fraser, G.R., Colombatto, D., McAllister, T.A. and Beauchemin, K.A. (2008). A review of plant-derived essential oils in ruminant production and nutrition. Animal Feed Science and Technology 145: 209–228.

Calsamiglia, S., Busquet, M., Cardazo, P.W., Castillejos, L. and Ferret, A. (2007). Invited Review: Essential oils as modifiers of rumen microbial fermentation. Journal of Dairy Science 90: 2580–2595.

Chilliard, Y., Martin, C., Rouel, J. and Doreau, M. (2009). Milk fatty acids in dairy cows fed whole crude linseed, extruded linseed, or linseed oil, and their relationship with methane output. Journal of Dairy Science 92: 5199–5211.

Newbold, J. (1997). Proposed mechanisms for enzymes as modifiers of ruminal fermentation. IFAS Dairy Proceedings, Florida.

Soyeurt, H., Dardenne, P., Dehareng, F., Lognay, G., Veselko, D., Marlier, M., Bertozzi, C., Mayeres, P. and Gengler, N. (2006). Estimating fatty acid content in cow milk using mid-infrared spectroscopy. Journal of Dairy Science 89: 3690–3695.

Zachut, M., Arieli, A. and Moallem, U. (2011). Incorporation of dietary n-3 fatty acids into ovarian compartments in dairy cows and the effects on hormonal and behavioural patterns around oestrus. Reproduction 141: 833–840.