Feed Strategy - November 2019 - 29

FeedStrategy ❙ 29

Dairy cows fed corn silage-based diets
with low protein content at the end of
the lactation can maintain performance.
Grafissimo | iStockPhoto.com

therefore different potentials of production
and intake capacity; and
■ The use of security factors because of
quality differences in the feed used in the
formulation of the diets.
These reasons are complemented by the
fact that, while a protein deficit significantly
reduces cow intake and production, its excess
does not affect the former and has limited
effects on the latter.

Energetic cost of feeding
protein in excess
Feeding protein above requirement requires
the use of additional energy to metabolize
excess nitrogen and excrete it in the form of
urea. A recent study published in the Journal of
Dairy Science estimated the energetic cost of
feeding excess dietary nitrogen to dairy cows.
The researchers used a data set containing 1,110 indirect
calorimetry observations from 64 experiments conducted
at the United States Department of Agriculture (USDA)
Energy and Metabolism Laboratory. The data set was
composed of individual daily nutrient balance and indirect calorimetry observations from lactating dairy cows.
The results show nitrogen fed above requirement:
■ Increases heat production
(+4.1 to +7.6 kcal/g of excess N)
■ Decreases retained energy
(−4.2 to −6.6 kcal/g of excess N)
■ Reduces milk gross energy
(−52 to −68 kcal/g of excess N).
Since protein is one of the most expensive nutrients
in lactation diets and an excess of nitrogen supply may
reduce energy availability in the animal, much research
has focused on feeding low-protein diets, mainly to latelactation cows whose metabolizable protein requirements are lower than cows in early lactation.
November 2019 ❙ www.FeedStrategy.com

Low-protein dairy cow diets 
A recent study published in ANIMAL evaluated
the effects of feeding a reduced protein diet on the
productive performance of late-lactation cows. Using
a split-plot design over four periods of two weeks, the
researchers fed late-lactation cows with two diets that
contained 17 or 12% protein in a dry matter (DM)
basis. The diets contained corn silage as the only
forage (79.5% DM) and a soybean meal mix as the
main protein supplement.
Surprisingly, cows receiving the low-protein
diet maintained production performance. Although
decreasing protein level from 17 to 12% reduced
slightly DM intake and milk fat yield (0.8 and 0.04 kg/
day, respectively), milk production (25.8 kg/d), milk
fat concentration (4.27%), and protein concentration
and yield (3.15% - 0.81 kg/d) were not affected by diet.
Moreover, the 12% protein diet drastically improved
nitrogen use efficiency (31 vs. 22%).

Nutritional factors that influence milk quality,
composition: https://bit.ly/35918rZ

In summary, this study demonstrates that dairy
cows at the end of the lactation fed corn silage-based
diets with low protein content can keep performance,
at least for periods of two weeks. Although these
results are very promising, they should be taken with
caution because the testing periods were very short
(only two weeks).

Incrementally reduced protein diets
Another study conducted at the University of Wisconsin-
Madison measured performance of late-lactation cows
fed diets with incremental reductions in protein levels.
In this case, the researchers fed pregnant cows with four
diets that contained 16.2, 14.4, 13.1, or 11.8% protein
in DM basis for 12 weeks. The diets contained 65%
forage, 13.5% corn, and 21.5% concentrate mix in which
soybean meal was replaced with soy hulls for reducing
protein level. Decreasing protein levels from 16.2% to


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Feed Strategy - November 2019

Table of Contents for the Digital Edition of Feed Strategy - November 2019

Feed Strategy - November 2019
Contents
In the Mix
FeedStrategy.com
Climate change and animal feed: mycotoxin risk mitigation
How to adapt to the changing mycotoxin landscape
Scientists seek new ways to combat spread of mycotoxins
Feed additives that will succeed in 2020 and beyond
Marketing nutrition by extending credit
More feed, fewer mills: feed industry consolidation
How to target protein content in late-lactation cow diets
Critical junctures in early chick nutrition confi rmed
How pelleting influences particle size in animal feed
Products
Advertisers’ Index
Feed Strategy - November 2019 - CT1
Feed Strategy - November 2019 - CT2
Feed Strategy - November 2019 - Feed Strategy - November 2019
Feed Strategy - November 2019 - Cover2
Feed Strategy - November 2019 - CT3
Feed Strategy - November 2019 - CT4
Feed Strategy - November 2019 - Contents
Feed Strategy - November 2019 - In the Mix
Feed Strategy - November 2019 - FeedStrategy.com
Feed Strategy - November 2019 - Climate change and animal feed: mycotoxin risk mitigation
Feed Strategy - November 2019 - 5
Feed Strategy - November 2019 - 6
Feed Strategy - November 2019 - 7
Feed Strategy - November 2019 - How to adapt to the changing mycotoxin landscape
Feed Strategy - November 2019 - 9
Feed Strategy - November 2019 - 10
Feed Strategy - November 2019 - 11
Feed Strategy - November 2019 - Scientists seek new ways to combat spread of mycotoxins
Feed Strategy - November 2019 - 13
Feed Strategy - November 2019 - 14
Feed Strategy - November 2019 - 15
Feed Strategy - November 2019 - Feed additives that will succeed in 2020 and beyond
Feed Strategy - November 2019 - 17
Feed Strategy - November 2019 - 18
Feed Strategy - November 2019 - 19
Feed Strategy - November 2019 - 20
Feed Strategy - November 2019 - 21
Feed Strategy - November 2019 - Marketing nutrition by extending credit
Feed Strategy - November 2019 - 23
Feed Strategy - November 2019 - More feed, fewer mills: feed industry consolidation
Feed Strategy - November 2019 - 25
Feed Strategy - November 2019 - 26
Feed Strategy - November 2019 - 27
Feed Strategy - November 2019 - How to target protein content in late-lactation cow diets
Feed Strategy - November 2019 - 29
Feed Strategy - November 2019 - 30
Feed Strategy - November 2019 - Critical junctures in early chick nutrition confi rmed
Feed Strategy - November 2019 - 32
Feed Strategy - November 2019 - 33
Feed Strategy - November 2019 - How pelleting influences particle size in animal feed
Feed Strategy - November 2019 - 35
Feed Strategy - November 2019 - 36
Feed Strategy - November 2019 - 37
Feed Strategy - November 2019 - 38
Feed Strategy - November 2019 - Products
Feed Strategy - November 2019 - Advertisers’ Index
Feed Strategy - November 2019 - Cover3
Feed Strategy - November 2019 - Cover4
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