Abstract
Inefficient rumen microbial fermentation is a major factor limiting intake of low quality roughage in ruminants. In this study, the effect of energy supplementation on rumen microbial fermentation, absorption of balanced digestion products and voluntary feed intake in sheep was investigated. A basal diet of a urea-treated mixture of wheaten chaff and barley straw (3:1 DM) containing 22.2 g N/kg DM was used. Four Merino-cross wethers weighing and fitted with permanent rumen and abomasal cannulae were allocated to four treatments in a Latin square design. The dietary treatments were basal diet (), or basal diet supplemented with sucrose (112.5 g/d) administered to the animals intra-ruminally (), abomasally (), or through both routes (50:50) (). Feed intake (basal and dietary) was increased (p) or abomasum (). However, there was no difference (p>0.05) in intake between animals on the control diet and those supplemented with sucrose through both intraruminal and abomasal routes (). The digestibility of DM and OM was highest in and supplemented animals. Although the rumen pH was reduced (p), the in sacco degradation of barley straw in the rumen was not adversely affected (p>0.05). Intra-ruminal sucrose supplementation resulted in a higher concentration of total VFA, acetate and butyrate, while the pattern of fermentation showed a higher propionate: acetate ratio. Intra-ruminal supplementation also increased (p0.05) in microbial protein production between the four dietary treatments. Protozoa numbers were increased (p
Highlights
Low quality roughages such as cereal straw and stover are generally high in fibre but low in key nutrients such as nitrogen (N), minerals such as sulphur and readily fermentable carbohydrates (Preston and Leng, 1987)
For total diet and basal roughage were significantly higher in animals supplemented with sucrose intra-ruminally (ER) compared to those on the control diet or supplemented with sucrose through both the rumen and abomasum (ERA) (Table 4)
The dry matter (DM) and organic matter (OM) intake of total diet and basal roughage were not significantly different (p>0.05) from those of animals supplemented with sucrose abomasally
Summary
Low quality roughages such as cereal straw and stover are generally high in fibre but low in key nutrients such as nitrogen (N), minerals such as sulphur and readily fermentable carbohydrates (Preston and Leng, 1987). As a result, they are poorly utilized by ruminants mainly due to a combination of high cell wall contents (CWC), low microbial growth and fermentation activity in the rumen (Ferrell et al, 1999). Energy supplementation has been reported as being variably successful in enhancing digestibility and intake of basal roughage (Ørskov 1986; Lee et al, 1987; Fonseca et al, 2001).
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