BALANCING USE OF CORN SILAGE AND ALFALFA IN DAIRY RATIONS
 
R. D. Shaver
 
Department of Dairy Science
College of Agricultural and Life Sciences
University of Wisconsin Madison
University of Wisconsin Extension
 
 

 

Recently, in Wisconsin, dairy producers have been feeding their lactating cows a higher proportion of corn silage relative to alfalfa than was common in the past. Some of the factors in favor of corn silage that are partially responsible for this trend include:

 

 

Dairy producers are asking the following questions:

 

 

 

NUTRITIONAL CHARACTERISTICS OF CORN SILAGE vs. ALFALFA
 

Good quality corn silage and alfalfa compliment each other well in dairy rations. Their nutritional characteristics are presented in Table 1. Combining corn silage and alfalfa in dairy rations at moderate rates helps minimize deficiencies or excesses that may result from feeding either forage at a very high rate or as the sole forage.

 

 

Table 1. Nutritional characteristics of good quality corn silage vs. alfalfa.
 
Content or trait
Corn Silage
Alfalfa Silage
Alfalfa Hay
Moisture
High
Moderate to High
Low
Acidity
High
Moderate
Low
Buffering Capacity
Low to Moderate
High
Moderate to High
Bunk Stability
Low
Moderate to High
High
Starch
Moderate to High
Low
Low
Energy
High
Moderate to High
Moderate to High
Protein
Low
High
High
DIP1
Low
High
Moderate to High
Macro-mineral
Low
High
High
ADF
Low
Moderate
Moderate
NDF
Moderate
Moderate
Moderate
Effective Fiber
Low to Moderate
Moderate to High
High
1Degraded intake protein as a % of DM.

 

 

CORN SILAGE vs. ALFALFA SILAGE AND LACTATION PERFORMANCE
 

Researchers at the U. S. Dairy Forage Research Center (Dhiman and Satter, 1997) assessed lactation performance of dairy cows fed different proportions of alfalfa silage and corn silage. Forty-five mature and 29 first-lactation Holstein cows were used in a full-lactation trial. Cows were fed diets with a 50:50 forage to concentrate ratio. The forage DM in the diet contained either all alfalfa silage (AS), 2/3rd alfalfa silage:1/3rd corn silage (1/3 CS), or 1/3rd alfalfa silage:2/3rd corn silage (2/3rd CS). The silages used in the trial were of good quality averaging 40% DM-19.5% CP-40% NDF and 36% DM-8% CP-45% NDF for the alfalfa silage and corn silage, respectively. Diets were formulated to equal concentrations of UIP (% of DM) and energy (Mcal NEl per lb. DM) by varying the proportions of high-moisture corn, soybean meal, roasted soybeans, and tallow. Trial results are presented in Table 2.

 

Table 2. Lactation performance of dairy cows fed different proportions of alfalfa and corn silage.
 
Item
AS
1/3rd CS
2/3rd CS
(P<)
DMI, lb/d
46
47
46
NS
DMI, % BW
3.51
3.75
3.57
.05
Milk, lb/d
68
71
69
NS
FCM, lb/d
68
72
70
.15
Fat, %
3.53
3.67
3.65
NS
CP, %
3.08
3.15
3.19
.08
305-d Milk, lb
       
Mature
21,105
22,374
22,053
NS
1st-Lactation
17,873
18,506
17,970
NS
 

Lactation performance was good for all diets, but there was a slight advantage for the 1/3rd corn silage diet. There appears to be reasonable flexibility between 1/3rd and 2/3rd of the forage DM as corn silage for animal performance. Forage inventory, crop rotation, risk management, and feed cost considerations largely determine what proportion of corn silage to feed within this range. An upper feeding limit of 2/3rd -3/4th of the forage DM as corn silage is recommended, because of its high moisture, acidity, starch, and energy content and low effective fiber content (Refer to Table 1). Manure nutrient management, risk management, and feed cost considerations also factor into this recommendation.

 

 

BALANCING CORN SILAGE BASED RATIONS
 

Suggested ration changes when switching from a low to a high proportion of forage DM as good quality corn silage are as follows:

 

 

 

REFERENCES
 

Dhiman, T. R., and L. D. Satter. 1997. Yield responses of dairy cows fed different proportions of alfalfa silage and corn silage. J. Dairy Sci. 80:2069-2082.