Feed & Additive Magazine Issue 2 March 2021

ARTICLE 68 FEED & ADDITIVE MAGAZINE March 2021 R uminant production systems convert vegeta- ble protein into animal protein, contributing substantially to human nutrition by the production of milk and meat. Ruminal micro-organisms pro- cesses lignocellulose from low quality roughage into volatile fatty acids and energy, to transfer non-pro- tein nitrogen into microbial protein. This is how ru- minants can produce food of animal origin without competition for feed with non-ruminants and hu- mans. Feed-efficient ruminant production is a com- plex system starting in many situations with a better nitrogen (N) efficiency (Flachowsky et al., 2013). Depending on the animal species, ration, and man- agement, between 5% and 45% of the nitrogen (N) in the vegetable protein is converted and deposited in the meat or milk. The other 55%-95% is excreted (urine or manure) and can be used as a source of nu- trients for plant production (Oenema and Tammin- ga, 2005). However, the efficiency of re-conversion of the N into plant protein is limited. Only a maximum of 60% of the N applied to the soil can be convert- ed to vegetable protein. The rest is lost, contributing to the environmental problem. This is especially im- portant when we consider that the estimated overall amount of N excreted by animals is comparable with the annual consumption of N fertilizers, if not higher. Strategies to reduce losses and improve efficiency of ruminant production systems rely on an optimal supply of rumen degradable N and an optimal effi- ciency of utilisation of absorbed amino acids (Dijk- stra et al., 2013). Generally, in ruminants the ob- served efficiency of conversion between N consumed and N deposited into protein varies between 20 to 32%, but the maximum theoretical efficiency should be between 40 to 45% (Van Vuuren and Meijs, 1987; Hvelplund and Madsen, 1995; Dijkstra, 2013). A practical objective would be to achieve around 40% conversion, this goal can be reached by formulating for low crude protein (CP) and balancing for amino acids (AA’s), as described in this article. Ruminant protein nutrition has three big chal- lenges. Firstly, the rumen contains high numbers of micro-organisms which makes balancing the protein profile difficult, and typically leads to a very low feed and nitrogen efficiency. Secondly, it is not al- ways easy to obtain high fodder quality which pro- vides energy in enough quantity (minimum 40% of the total dry matter intake to avoid health problems and an even lower efficiency). Finally, it is crucial REDUCE NITROGEN EXCRETION AND PRODUCE MORE EFFICIENTLY Strategies to reduce losses and improve efficiency of ruminant production systems rely on an optimal supply of rumen degradable nitrogen and an optimal efficiency of utilisation of absorbed amino acids. Reducing nitrogen excretion should be an opportunity for ruminants to produce more efficiently. Diego Martínez, PhD Product Manager Amino Acids Kemin Animal Nutrition and Health – EMENA