Abstract
The effects of the nonionic surfactant Tween 80 and a mixture of fibrolytic enzymes on total tract digestion, in situ disappearance (ISD) and ruminal fermentation characteristics of orchardgrass hay and barley grain were investigated in a 4x4 Latin square experiment with 4 non-lactating Holstein cows and 4 diets in 4 periods. Cows were offered a total mixed ration of 50% rolled barley grain and 50% orchardgrass hay treated with either 1) water (control), 2) 0.2% (vol/wt) Tween 80, 3) 0.2% (vol/wt) hydrolytic enzyme, or 4) 0.2% hydrolytic enzyme plus 0.2% Tween 80. Total tract digestibility coefficients of DM, nitrogen, NDF and ADF were not affected (p>0.05) by dietary treatment. Compared to the control, the rate of ISD of DM from orchardgrass hay was faster (p 0.05) by treatments. Cows that consumed diets treated with enzyme plus Tween 80 had higher (p<0.05) ruminal concentrations of propionate and isovalerate, and lower (p<0.05) acetate:propionate ratios. Compared to the control, microbial protein synthesis tended (p = 0.13) to increase with the addition of enzyme to the diet while non-ammonia nitrogen flow to the duodenum increased (p<0.05) with both enzyme and Tween 80 treatments. The study indicated that fibrolytic enzymes alone or in combination with Tween 80 could enhance ISD of orchardgrass hay and ruminal concentrations of propionate, valerate and iso-valerate, but do not affect total tract digestibility.
Highlights
To increase DM intake and milk production (Lee et al., The nonionic surfactant Tween 80, has been shown in in 2003) in cattle
Orchardgrass hay incubated in the rumen of cows on the T treatment had the highest (p
The specific rate of in situ DM disappearance of used by Hristov et al (1998) contained 60% rolled barley orchardgrass hay was increased when cows received the diet treated with exogenous fibrolytic enzymes, total tract digestibility of nutrients were unaffected
Summary
To increase DM intake and milk production (Lee et al., The nonionic surfactant Tween 80, has been shown in in 2003) in cattle. Despite these reports of enhanced digestibility of the orchardgrass diet increased enzyme and microbial activities, attempts have been made simultaneously (Kamande, 1994), it is possible that Tween only recently to determine if this surfactant will elicit 80 improved the efficiency of the digestive enzymes as similar responses in vivo, with consequent improvements in evidenced by the in vitro results reported above. Lewis et al (1999) observed higher DM intake and lactational performance in early and mid-lactation cows receiving diets treated with exogenous fibrolytic enzymes. The objectives of the present experiment were to determine the effects of combining the nonionic surfactant, Tween 80 and exogenous fibrolytic enzymes on ruminal fermentation, in situ disappearance and total tract digestibility of feeds in dairy cows.
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