Over 230 participants attended the seventh International Dairy Nutrition Symposium, organized by the Centre for Animal Nutrition, co-organised with Balchem Corporation, Diamond V, Dupont Pioneer and the Wageningen Institute of Animal Sciences. Seven experts shared their views on “Feed efficiency in dairy cattle”, leading to one general conclusion: there is more to dairy feed efficiency than just calculating a ration.
First speaker Dr. Theun Vellinga (Wageningen UR Livestock Research, The Netherlands) discussed the variation in dairy systems and feed efficiency in various parts of the world. In Western-Europe and North-America about 10-15% of the total global number of dairy cows produce almost 50% of total global milk production. In South-America, Africa and Asia production and feed efficiency are much lower with about 2 to 7 times higher CO2 production per kg FPCM, due to a lower digestibility of the feedstuffs and use of less degradable crop residues as part of the ration. Dr. Bill Mahanna (DuPont Pioneer and Iowa State University, USA) continued with the factors influencing the backbone of the dairy ration: forage quality. By focussing on harvest maturity, chop length, conservation as well as feedout, dairy feed efficiency can be significantly improved. Dr. Kevin Leahy (Diamond V, USA) showed that the right ration mixing conditions are also of high importance. Variation at the face of the silage is very high, and this variation will only be larger at the feeding gate if the ration composition is insufficiently mixed, e.g. by worn mixer parts or improper positioning of the wagon during mixing; causing reduced feed efficiency.
After the lunch break Prof. Karl-Heinz Südekum (Bonn University, Germany) gave a structured overview of the various feed additives that are available to improve feed efficiency. Amongst others, the addition of yeasts or non-protein nitrogen sources contribute to efficiency, depending on the specific circumstances at the dairy farm. Dr. Jan Dijkstra (Wageningen University, The Netherlands) continued with an analysis of nutrient losses in the cow. He showed that ruminants are net producers of high quality protein for human consumption. Most variation in feed efficiency between cows is caused by differences in fermentation and passage in the rumen. Important losses for efficiency are methane production and costs of digestion and absorption, especially with less digestible feeds. Prof. Chris Reynolds (Reading University, UK) presented the results of studies aiming at maximizing protein efficiency in dairy cattle. Reducing protein intake showed to be most effective, but is often accompanied by reduced milk (protein) yield and also long term effects need to be investigated. The theoretical maximum of 40-45% nitrogen efficiency in ruminants cannot be reached in practice due to suboptimal digestion and by the presence of the rumen, interfering in the supply of specific amino acids. Dr. Ad van Vuuren (Wageningen UR Livestock Research, The Netherlands) was the final speaker of the day, with an interesting analysis of the impact of animal health and longevity on dairy feed efficiency, with an important role for the transition period. Professional management of the transition period is required to prevent health disorders and inefficiency, which goes far beyond improving energy intake.