NUTRITION ▶▶▶ Up to 80% of energy supply to ruminants comes from Volative Fatty Acids.
sufficient essential amino acids supply for absorption in the gut. However, rumen capture and degradation of proteins as well as microbial synthesis variation can randomly change the amount and profile of MP supplied to the gut, which can- not be easily controlled in farming conditions. Up to 80% of energy supply to ruminants comes from VFA. Rumen fermen- tations produce mainly acetic, butyric, lactic and propionic acids. Levels and ratio of each VFA for optimum rumen effi- ciency have been determined after years of research and con- stitute nutrition standards. Due to a high level of concen- trates in modern dairy farming, rumen functioning can be disturbed and this can lead to misbalanced ratios of VFA. An increase of concentrates intake has been shown to increase acetic and lactic acids production and to decrease ruminal pH. In the short term this strategy can in fact lead to more VFA production from important and rapid starch degradation of concentrates. But constant drops in ruminal pH causes a non-ideal condition for cellulolytic flora development. This leads to the decrease of fibre digestibility, whereas it ac- counts for a consequent amount of ruminants’ diets. Both protein and energy efficiency are important and furthermore, correlated. Indeed, microbial synthesis of protein is energy dependent, and recent research has shown that “synchronis- ing” the timing of energy supply with protein degradation may maximise protein synthesis and minimise nitrogen waste into ammonia.
Which strategies to increase feed efficiency? Starting with fundamentals, feedstuffs should be chosen for their digestibility and nutrient bioavailability. Such parame- ters can be monitored with indicators such as: Total Digestible Nutrients (% of Dry Matter), Digestible Energy (Mcal/kg), Pro- tein Digestion rate (%/h) or Metabolizable Protein (g/day).
34 ▶ DAIRY GLOBAL | Volume 5, No. 4, 2018
Then, as mentioned before, rationing should take into ac- count synchronisation and balance of ruminal protein and carbohydrates digestion. Since the last decades, specialities have emerged on the market, providing solutions to increase by-pass nutrients supply at the intestinal tract. They include source of proteins treated with different methods (formalde- hyde, heat, reducing sugars, etc.) and single amino acids protected from ruminal degradation by fat or ethyl-cellulose encapsulation. Whereas these solutions have shown consist- ent results on feed efficiency, they only provide a limited amount or type of nutrients to the animal’s gut. Then, anoth- er increasing approach is the use of phytogenics. There are numerous types of phytogenics and some of the most effec- tive ones for feed efficiency are: Tannins: complex polyphenol compounds of plants. They can vary a lot in types and con- centration from extraction. Their nature allows binding with protein, notably, but the quantity and the quality of the ex- tract is very important to ensure adequate binding in the ru- men and liberation in the gut. Secondly, essential oils: sec- ondary metabolites and volatile components. And thirdly, spices, such as paprika extracts. They have shown to increase dairy cows’ intake in different trials, and have been linked to an increase of the natural buffer from salivation positively affecting ruminal pH.
Tested in a Holstein herd One of these products, Valopro, has been recently tested in a different context in a field trial in Ontario, Canada. A herd of 70 Holstein dairy cows was supplemented with 20g/day of the product during four months, after one month of pre- experiment control. Milk yield increased from 29 to 32.2 litre/ cow/day, protein content from 3.15 to 3.27% and fat content decreased from 4.31 to 4.05% (mainly due to dilution). Pro- tein, energy and feed efficiency have been improved from 16, 15 and 15%, respectively, during this trial (Figure 1). In the context of the trial, due to the increase of milk production and the decrease of feed cost, the farmer revenue was increased by $ 58.3/day.
Conclusion There is a significant economic advantage to monitoring feed efficiency. It allows farmers to regularly adjust the nutri- tion of the herd in order to maximise income from milk pro- duction regarding feed price of the moment. The use of sin- gle or blend of phytogenics can be part of the global approach to increase feed efficiency. The implementation of these kind of products can be performed in two different ways: in top feeding or in diet optimisation, to increase performance or decrease the feed cost of diets without degrading animal performance.
References are available upon request. All information only for export outside Europe- an Union, USA and Canada.
PHOTO: MARK PASVEER
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