815 Effects of replacing dietary high moisture corn with dried molasses on production of dairy cows.

Broderick* and W. J. Smith, U.S. Dairy Forage Research Center, Madison, WI.

 

Eight primiparous and 40 multiparous (8 with rumen cannulae) Hol­stein were blocked by parity and DIM, randomly assigned to 4 blocks of 12 and fed TMR containing (DM basis): [1]40% alfalfa silage, 20% corn silage, 8% soybean meal, 2% added fat, 1% minerals and vita­mins, and 18% CF. Dietary sugar was varied by replacing rolled high moisture shelled corn (HMSC) with dried molasses. The 4 diets were: 0% molasses, 29% HMSC; 4% molasses, 25% HMSC; 8% molasses, 21% HMSC; or 12% molasses, 17% HMSC. Cows were fed the 0% molasses diet for a 2-wk covariate period, experimental diets for 8 wk, then the 0% molasses diet for another 2 wk covariate. Milk yield and DM1 were measured daily. Yield of milk components was determined one day in both covariates and every 2-wk in the 8-wk trial. Rumen sampling was in trial wk 4 and 8. The statistical model included block and covariate average. LS means are reported below. There was a linear increase in DM1 and linear decreases in milk/DMI and milk N/NI with increasing dietary sugar. There were quadratic responses in yield of FCM and fat, and rumen NH3, with increasing sugar; FCM and fat yield maxima and rumen NH3 minimum occurred at about 6% molasses. Several cubic re­sponses were noted that were related to similar milk and protein yields at 0 and 8% molasses. Replacing readily fermented starch with dietary sugar primarily increased fat yield.

 

Item Molasses, %

0

4

8

12

SE

HMSC, %

29

25

21

17

 

DM1, kg/d

25.1

25.8

26.2

26.0

0.3

Milk, kg/d

38.0

37.5

38.9

36.7

0.6

Milk/DMI

1.51

1.46

1.48

1.43

0.02

Milk N/NI

0.255

0.244

0.254

0.231

0.006

3.5% FCM, kg/d

41.4

42.0

43.4

39.5

1.0

Fat, %

4.07

4.26

4.11

4.06

0.10

Fat, kg/d

1.54

1.59

1.63

1.47

0.04

Protein, %

3.12

3.09

3.11

3.04

0.04

Protein, kg/d

1.19

1.14

1.23

1.09

0.03

True protein, kg/d

1.14

1.09

1.17

1.05

0.03

SNF, kg/d

3.38

3.30

3.49

3.18

0.08

Rumen NH3, mM

11.3

    9.1

10.7

10.7

0.5

% Sugar in TMR – DM basis                    2.6            4.2              5.6             7.2

via personal communication

Abstract presented at 2001 joint ASAS/ADSA annual meetings


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