Elsevier

Journal of Dairy Science

Volume 81, Issue 10, October 1998, Pages 2657-2669
Journal of Dairy Science

Article
Diet Choice by Dairy Cows. 1. Selection of Feed Protein Content During the First Half of Lactation

https://doi.org/10.3168/jds.S0022-0302(98)75823-0Get rights and content
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Abstract

Effects of weeks in milk and milk yield on diet choice were recorded during the first half of lactation. Low and high protein feeds were used, and both consisted of 30% concentrate and 70% grass silage (fresh matter basis). Both feeds contained similar amounts of energy, but the crude protein contents were 131 and 185 g/kg of dry matter (DM), respectively, for the low and high protein feeds. In a nutrient flow experiment with three cannulated lactating cows, the metabolizable protein yields of the low and high protein feeds were 75 and 114 g/kg of DM, respectively. Thirty-seven cows were divided into control groups for the low and high protein feeds, and a choice group had access to both the low and the high protein feeds. Intake of DM and milk yield by cows in the control group fed the high protein feed were higher than those by cows in the control group fed the low protein feed, but these measurements did not differ from those of cows in the choice group. Cows in the choice group consumed a mean of 683 g of high protein feed/kg of total intake, which differed from what would be considered random intake (500 g/kg total intake). Diet choice did not systematically change during the experiment and was not correlated with weeks in milk, milk yield, or milk protein output. We concluded that diet selection differed significantly from what would be considered random, which allowed cows in the choice group to perform well. However, diet choice did not reflect the estimated metabolizable protein requirements of the cows.

Key words

cows
diet selection
protein
lactation

Abbreviation key

CG
choice group with access to LPF and HPF
CHPF
control group fed HPF
CLPF
control group fed LPF
HPF
high protein feed
LPF
low protein feed
ME
metabolizable energy
MP
metabolizable protein
MY
milk yield
SED
standard error of the difference
2/3H + 1/3L
feed consisting of two-thirds HPF and one-third LPF

Cited by (0)

1

Present address: Research Center Foulum, PO Box 50, DK 8830 Tjele, Denmark.

2

Present address: Institute for Animal Science, PO Box 65, 8200 AB Lelystad, The Netherlands.