Statistical research on the digestibility in the cow. I. Dry matter and energy

SUMMARY The results obtained for dry matter and energy digestibility with 116 different rations fed to 242 non-pregnant dry cows and 96 laotating cows were studied. With winter rations, dry-matter digestibility ( Y ) is linearly related to dry-matter intake ( X 1 ) and to the crude fibre content of the dry matter ( X 2 ): Y = 89·58–0·557 X 1 –0·863 X 2 . A similar equation was obtained for energy digestibility ( Y ): Y = 90·68–0·195 X 1 –0·892 X 2 , where X 1 represents the energy intake (in 1000 kcal) and X 2 the crude-fibre content. Digestible dry matter or energy can be estimated very accurately from dry matter or energy intake and from crude-fibre content. There is a highly significant linear relation between dry matter or energy digestibility and nitrogen concentration of the faeces, especially with grass. Dry-matter digestibility is also influenced by the physical form of the feeds and by individual factors.