Milk yield and milk components of dairy cows during excessive protein supply with special regard to grazing conditions

Paulicks, B.R.; Kirchgessner, M.; Schwarz, F.J.

Wirtschaftseigene Futter 33(1): 44-60

1987


Accession: 005902525

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Abstract
In two feeding trials (A and B) with a total of 26 and 24 dairy cows divided into two groups (K and .ovrhdot.U) the direct and residual effects of excessive protein supply on milk yield and on the contents of milk fat and milk protein were to be examined. Therefore in trial A where the animals were in stall the whole day long nearly 600 g crude protein were daily given in excess to the cows in group .ovrhdot.U over 4 weeks (period P1). Group K got a protein supply adequate to requirement. In trial B the supply of crude protein for group U was raised about 400 g/d 4 weeks long (periods P0 and P1) by feeding only pasture instead of a pasture-maizesilage-ration. During the following 6 weeks (period P2 in trial A) or 4 weeks (period P2 in trial B) the protein supply for the animals in group U was adapted to the control niveau (group K). The energy supply was always covering the requirement. In trial A there were no persistent changes in milk yield which could be attributed to the treatment. The average daily milk yield was 23.5 kg in period P0, 21.2 kg in period P1, and 19.1 kg in period P2. Also the contents of milk fat (4.0%) and milk protein (3.4%) showed neither direct nor residual effects of the excessive protein supply. In trial B unrelated to the treatment (K or U) the daily milk yield fell from an average of nearly 26 kg (P0) to 23.5 kg (P1) but then raised again to about 24.5 kg in period P2. Despite supplies of crude fibre and net energy which were calculated to be sufficient for the production the contents of milk fat (3.7%) and milk protein (3.2%) were rather low. Neither direct nor residual effects of the different protein supplies could be observed.