Increased level of dietary sugar is known to improve dairy cow performance. To evaluate the level of sugar on cow
performance, a recent meta-analysis containing data from 24 published research papers (97 lactating diets) was
conducted. This research was published in Professional Animal Scientist (de Ondarza et al. 2017. 33: 700-707). The
paper found that multiple dietary factors, including starch, soluble fiber, protein, and NDF, all influence dairy cow
response to feeding additional dietary sugar. Yields of fat-corrected milk yield and protein were optimized with the
inclusion of 5 to 7% additional sugar to the diet DM. The added sugar (approximately 1.5-2.2 lbs) brings the total
dietary level to 6.75-8% of DM.
Looking more closely at several studies utilized in the meta-analysis, at approximately 7% total sugar in the diet
DM, improvements in NDF and ADF digestibility were noted (Broderick & Radloff, 2004; Broderick et al., 2008).
Greater fiber digestibility provides additional energy and microbial protein to the cow, helping to increase production
of milk fat and protein. A total sugar level of 7.2% was identified for optimal milk protein content, through quadratic
regression analyses in the study of Broderick & Radloff (2004). Feeding a diet with approximately 7% total sugar
(5% added sucrose) also maximized yield of FCM (+6.8 lb/d), and fat (+0.4 lb/d) compared to control cows in the
study of Broderick et al., 2008. Feeding 4-6 lbs of molasses-based liquid feeds can provide needed levels of
supplemental sugar to increase productivity. Providing 5.8 lbs of a molasses-based liquid feed increased production
of ECM (+7 lb/d), milk fat (+0.28 lb/d), and milk protein (+0.19 lb/d) in the study of DeVries & Gill (2012).
Higher producing cows had greater responses to dietary sugar (P <0.0001). With 5 to 7% added dietary sugar (% of
DM), cows producing > 73 lbs of milk/d increased 3.5% FCM by 4.7 lbs/d (83.1 vs. 87.8 lbs/d). In comparison, cows
producing < 73 lbs of milk/d increased 3.5% FCM by 1.7 lbs/d. Likewise, when 5-7% sugar was added to the diet,
cows producing >73 lbs of milk/d increased milk true protein production (P <0.0001) by 0.2 lb/d, compared to 0.1 lb/
day increase for cows producing <73 lbs of milk/d. Days in milk was also an important factor in response to added
sugar, as the meta analysis indicated that greatest responses to supplemental sugar occur in the first 165 DIM.
For optimal yield response of 3.5% fat-corrected milk when supplemental sugar is fed, it is recommended to feed a
diet with low to moderate starch (22 – 27% of diet DM) and moderate to high soluble fiber (6.0 – 8.5% of diet DM).
Response to molasses-based liquid supplements was optimized when the following ration guidelines were used
when formulating lactating cow diets (Table 1).
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