nXP (animal nutrition)
nXP is the common abbreviation for usable crude protein on the duodenum (small intestine) . It therefore characterizes the amount of crude protein that dairy cows can ingest from feed in the small intestine .
The protein available in the intestine is basically composed of two components in ruminants:
- the bacterial protein formed in the rumen and the
- Raw feed protein (UDP) not degraded in the rumen .
The extent of bacterial protein synthesis depends essentially on the rumen-available nitrogen and energy levels in the feed, the ratio of which is determined in ration calculations using the ruminal nitrogen balance (RNB). The nXP content only applies if the rumen microbes are adequately supplied with nitrogen.
The nXP is given in grams of content per kilogram of dry matter of the feed. The nXP for wheat is around 150 g / kg dry matter.
Dairy cow requirement figures
A cow with a live weight of 700 kg has a maintenance requirement of 470 grams of nXP per day. In addition, there is a performance-related requirement of 85 g nXP per kilogram of milk. A 700 kg cow with a production of 30 kg milk with 3.4% protein has an nXP requirement of 3020 g per day, for a comparable animal with 40 kg milk it would be 3870 g nXP. In order to determine the required concentration of nXP in the feed mixture, the requirement must be divided by the daily intake of dry matter.
Depending on the amount of milk, the nXP in the feed mixture should be between 140 g / kg and 170 g / kg dry matter.
See also
Web links
- Care of dairy cows, page 12 (PDF; 100 kB)