1755
Evaluation of Celmanax® SCP on Lactational Performance and Ruminal Fermentation of Holstein Dairy Cows Fed Corn Silage Based Diets with a Moderate Starch Content
Primiparous (n = 21) and multiparous (n = 39) Holstein cows averaging 123 ± 28 (SD) days in milk were used in a randomized complete block design (RCBD) study to evaluate the effect of supplemental yeast culture plus enzymatically hydrolyzed yeast cell wall (Celmanax SCP; Vi-COR, Mason, City, IA) on lactational performance and ruminal fermentation. Following a 2-wk covariate period with a yeast-free diet, cows (20/treatment) were fed a diet supplemented with 0, 3, or 5 g of Celmanax SCP per day for a 4-wk treatment period. The diet contained 30.8% bmr corn silage, 16.2% corn silage, 9.7% haycrop silage, and 43.3% concentrates with a nutrient content of 16.5% crude protein, 36.3% neutral detergent fiber, and 24.3% starch. Cows were fed individually, housed in freestalls, and milked 3× daily. Dry matter intake (DMI) and milk yield were measured daily and milk composition was measured weekly. Fifteen ruminally cannulated cows (5/treatment) were sampled during the last week of the covariate and treatment periods for ruminal pH (72-h period) and volatile fatty acids (VFA; 24-h period). Data from wk 3 and 4 of the treatment period were analyzed as a RCBD by ANOVA using the MIXED procedure of SAS. Least squares means were adjusted using data from the covariate period. On average, cows ate 27.3 kg DMI/d and produced 45.5 kg milk/d containing 3.88% fat and 3.21% true protein. There was a quadratic effect of supplementing Celmanax SCP on feed efficiency with feed efficiency highest at 3 g/d. Ruminal pH averaged 6.05 over a 24-h period with 308 min/d below 5.8. Celmanax SCP supplementation linearly increased the concentration of total VFA and acetate with no effect on propionate. Supplementation of Celmanax SCP improved feed efficiency potentially through changes in ruminal fermentation.
Item |
0 g/d |
3 g/d |
5 g/d |
SE |
Linear P |
Quadratic P |
DMI, kg/d |
27.4 |
27.1 |
27.4 |
0.2 |
0.87 |
0.20 |
Milk, kg/d |
45.3 |
45.9 |
45.4 |
0.4 |
0.82 |
0.36 |
Solids-corrected milk, kg/d |
44.8 |
45.4 |
44.6 |
0.6 |
0.80 |
0.33 |
Fat, % |
3.88 |
3.90 |
3.86 |
0.05 |
0.78 |
0.54 |
True protein, % |
3.23 |
3.20 |
3.20 |
0.02 |
0.35 |
0.69 |
Milk/DMI |
1.66 |
1.70 |
1.66 |
0.01 |
0.82 |
0.01 |
SCM/DMI |
1.64 |
1.69 |
1.63 |
0.02 |
0.87 |
<0.01 |
Ruminal pH |
6.11 |
6.02 |
6.03 |
0.08 |
0.38 |
0.70 |
Total VFA, mM |
128.6 |
138.2 |
141.9 |
3.7 |
0.01 |
0.72 |
Acetate, mM |
71.0 |
76.2 |
79.9 |
2.0 |
<0.01 |
0.94 |
Propionate, mM |
27.0 |
29.9 |
29.4 |
1.3 |
0.17 |
0.37 |
Keywords:
yeast culture, dairy cow, lactational performance