664
Effects of feeding slow release NPN and microbial fermentation extracts on lactation performance of high-producing dairy cows
The objective of this study was to examine the effects of partial substitution of soybean meal with a product containing slow release NPN and microbial fermentation extracts [(OPT); Optimase® Alltech Inc., Nicholasville, KY)] in diets with two forage concentrations. Sixteen lactating Holstein dairy cows (4 primiparous and 12 multiparous) were randomly assigned to a 4 × 4 Latin square in a 2 × 2 factorial. High and low forage diets contained respectively 61% (HF) and 46% forage (LF), with (O) and without OPT (NO). Forage consisted of 75% corn silage and 25% alfalfa hay (DM basis). Experimental diets containing OPT (125g/cow/day) were designed to partially replace soybean meal 48 (0.625 kg) with forage fiber [corn silage (0.225 kg) and alfalfa hay (0.075 kg)] and non-forage fiber [soybean hulls (0.200 kg)]. Feeding cows HF versus LF reduced DMI, milk, ECM, protein %, and protein yield, but increased fat % (Table 1, P < 0.05). Feeding OPT decreased (P = 0.033) DMI 1.05 kg/d compared to diets without OPT. Milk yield decreased (P = 0.046) slightly with OPT inclusion; however, 4%FCM and ECM were not affected. Feeding OPT did not affect milk fat percentage and yield, lactose percentage, and total solids percentage and yield. Milk protein yield decreased (P= 0.013) 3.5% in cows fed OPT. OPT fed both in HF and LF diets as a partial replacement to soybean meal resulted in similar lactation performance (4% FCM and ECM) and feed efficiency despite a decrease in DMI and milk yield.
Table 1
|
HF |
LF |
|
P- value1 |
|||
Item: |
NO |
O |
NO |
O |
SEM |
F |
O |
DMI, kg/d |
26.4 |
25.5 |
29.5 |
28.3 |
0.76 |
<0.001 |
0.033 |
Milk, kg/d |
41.2 |
40.0 |
43.5 |
42.5 |
1.44 |
<0.001 |
0.046 |
4% FCM, kg/d |
42.3 |
40.9 |
43.0 |
42.7 |
1.25 |
0.165 |
0.362 |
ECM, kg/d |
44.8 |
43.1 |
46.1 |
45.6 |
1.25 |
0.038 |
0.247 |
Fat, % |
4.22 |
4.20 |
3.96 |
4.06 |
0.13 |
0.024 |
0.648 |
Fat, kg/d |
1.72 |
1.66 |
1.71 |
1.72 |
0.06 |
0.681 |
0.590 |
Protein, % |
3.07 |
3.00 |
3.14 |
3.14 |
0.05 |
<0.001 |
0.058 |
Protein, kg/d |
1.25 |
1.19 |
1.35 |
1.32 |
0.03 |
<0.001 |
0.013 |
ECM:DMI |
1.71 |
1.70 |
1.57 |
1.61 |
0.04 |
0.001 |
0.624 |
1 There were no interactions forage by OPT.
Keywords: slow-release-NPN, microbial fermentation extracts, dairy cows