Feherjeertekelesi rendszerek osszehasonlitasa a tejtermelo tehenek takarmanyozasaban.
1995
Varhegyi J.
Absorbed protein (AP, USA), metabolic protein (MP, Great Britain), amino acids absorbed in the small intestine and protein balance in the rumen (AAT-PBV, Nordic countries), crude protein flow at the duodenum (duodenal CP, Germany) and true protein digestible in the small intestine (PDI, France) were compared for dairy cows yielding 35, 25 and 15 kg milk/day. Systems differ in expressing energy supply for microbes, and digestible amino acid (AA) content of undegraded feed protein (UDP) depends on feed composition of rations in most systems. Three basic rations, including feeds widely used in Hungary, were formulated for 35, 25 and 15 kg/day milk production. Energy supply of microbes and digestible AA content of UDP were calculated from the same ration according to the different systems. Hungarian data was used for chemical composition, digestibility and for protein degradability (measured in sacco at authors' institute). Systems predict a similar crude protein requirement while there is a large variation in expected protein degradability. For 35 kg/day milk production, crude protein in dry matter and protein degradability vary between 15,6 (duodenal CP) - 16,6 (MP) , and from 73-74 (duodenal CP, MP) to 62 (AP, PDI) , respectively. Differences among the systems increase as milk production decreases. The main sources of variation are due to microbial crude protein production, digestible AA content of UPD originated from the same ration and protein requirement in absorbed protein. Expected protein degradability is highly dependent on the systems, level of milk production has a smaller effect. Without experiments and trials with dairy cows it cannot be judged which system is better in respect to expressing protein value of feeds and requirements for ruminants.
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