Abstract #T383

# T383
Ruminal fermentation characteristics of lactation dairy diets with different forage-to-concentrate ratios without or with lipid extract algae in continuous cultures.
S. Y. Yang*1, K. Neal1, J.-S. Eun1, A. J. Young1, R. C. Sims2, 1Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT, 2Department of Biological Engineering, Utah State University, Logan, UT.

The current in vitro experiment was performed to test the effects of supplementing lipid extract algae (LEA) in lactation dairy diets on ruminal fermentation in a 2 (level of forage in diets) × 2 (without vs. with LEA) factorial design with 4 independent runs of continuous cultures (n = 4). Diets with LEA completely replaced mixture of soybean meal and canola meal (50:50 in a DM basis). The data in this experiment were analyzed using the Proc Mixed procedure of SAS using a model that included fixed effects of level of forage, LEA supplementation, and their interaction and a random effect of fermentor within independent run. Feeding LEA decreased culture pH, regardless of level of forage, but the decrease of culture pH was greater under high-forage diet compared with low-forage diet, resulting in an interaction between level of forage and LEA. Under high-forage diet, total VFA concentration increased with feeding LEA, but it was not affected in low-forage diet, leading to a tendency (P = 0.08) of level of forage and LEA interaction. Adding LEA decreased ammonia-N concentration both in high- and low-forage diet. Overall results in this experiment indicate that feeding LEA in lactation dairy diets did not interfere with in vitro ruminal fermentation. The decreased ammonia-N concentration due to feeding LEA may have resulted from less degradation of N fraction in LEA compared with mixture of soybean meal and canola meal. Table 1. In vitro effects of lipid extract algae supplemented in dairy diets
ItemDiet1SEMP2
HFLF
–LEA+LEA–LEA+LEAFCLEAINT
Mean culture pH6.25a6.04b6.076.000.047<0.010.050.05
Total VFA, mM29.1b34.0a34.432.52.770.300.600.08
Individual VFA3
Acetate (A)46.147.347.347.73.920.210.330.53
Propionate (P)36.536.840.638.72.640.010.450.30
A:P1.261.291.191.240.1680.060.540.47
Ammonia-N, mg/dL8.045.366.543.100.403<0.01<0.010.31
a–bMeans within a row with different superscripts differ (P < 0.05). 1HF–LEA = high-forage diet (HF; 60% forage:40% concentrate) without lipid extract algae (LEA); HF+LEA = HF with LEA; LF–LEA = low-forage diet (LF; 40% forage:60% concentrate) without LEA; and LF+LEA = LF with LEA. 2FC = forage-to-concentrate ratio in the diet; LEA = supplementation of LEA; and INT = interaction between FC and LEA. 3Expressed as mol/100 mol.

Key Words: continuous culture, lactation dairy diet, lipid extract algae