Studies on ad libitum feeding for dairy cows. III. The effect of the protein content of diets for high-yielding cows in early lactation on intake, milk production, weight change, rumen parameters, and blood plasma characteristics

Hirada, H.; Katsunori, K.; Kobayashi, N.; Iwai, T.; Nase, T.

Research Bulletin of the Aichi ken Agricultural Research Center 16: 317-324


Accession: 001468174

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In wk 2-15 after calving, 9 high-yielding Holstein-Friesian cows (daily milk yield 30 kg) were in 3 groups given diets based on cubed hay, beet pulp, maize and soyabean meal and containing 72% TDN, 17% crude fibre and 20, 17 or 14.4% crude protein (CP) (digestible crude protein 15.7, 12.8 or 10.2%). Cows on the 14%-CP diet ate more than those on the 17%-CP diet, so that av. CP intakes of the 2 groups were similar, and lower than for cows given 20%-CP. The 17%-CP diet gave the highest av. daily milk yield, 37.7 vs. 32.5 kg, and best feed conversion to milk, but milk protein and SNF contents were lower with this diet than with 14%-CP or 20%-CP, at 2.8 and 8.2 vs. 3.3 and 8.9% resp. (P < 0.05 and P < 0.01). Rumen NH3 decreased as diet CP decreased, and blood NH3 was higher with 20%-CP than with the other diets. On the basis of the results a diet crude protein content of about 17% is recommended for high-yielding cows at the beginning of lactation.