Introduction. The use of biomass for energy production and biofuel seems to be the most promising alternative of this century, combining development and environment conservation (Hall et al., Reference Hall, House and Scrase2005). The Palm Kernel Cake (PKC), also known as Palm Kernel Meal, is estimated at having its production increased about 350% over the next five to 10 years due to Brazilian governmental programs for the palm industry. PKC is classified as a concentrate feed, mostly as an energetic source (Valadares Filho et al., Reference Valadares Filho, Magalhães and Rocha2006; NRC, 2001). This study was aimed at evaluating the intake, digestibility and in situ degradability of Dry Matter (DM), Crude Protein (CP), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), rate of passage and emptiness in buffalo receiving different levels of palm kernel cake (PKC) to determine its metabolic dynamics in the gastrointestinal tract.
Methods. Four (intake and digestibility-study 1) and three (in situ degradability, emptiness and rate of passage- study 2) crossbred river steer buffaloes cannulated in the rumen with initial live weights of 380.10 ± 27.21 Kg, kept under individual systems were fed increasing levels of Palm Kernel Cake–PKC (average of 8.23% Ether Extract) at 0, 20, 40 and 60% plus 100, 80, 60 or 40% of grass silage (Pennisetum purpureum). Animals were fed twice a day: 40% in the morning and 60% at the end of the afternoon. The Experimental design was a randomized block design for study 1 and a randomized block design in split plot arrangement for study 2. Four periods of 42 days each were used, with 14 to adjust intake and seven for each of the following studies: intake and digestibility, in situ degradability, rate of passage, and emptiness. During one year, the industry developed a standardized cake that was then used during the experiment.
Results and discussion. Best intake (%) and digestibility (%) level for DM, NDF, EE, CP, and digestible energy (DE) was determined to be at 60% of inclusion of PKC. The results of in situ Degradability can be seen in Table 1 and of emptiness in Figure 1.
Figure 1a and b. Mean values for voluntary feed intake of different leaves in growing pigs according to form of the distribution (fresh vs. dry meal).
Table 1 Percentage of Degradation Potential (Fractions A+B) in buffalo rumen fed different levels of PKC (Palm Kernel Cake)
**Dry Matter (DM), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Crude Protein (CP).
The rate of passage varied from 1.77 to 2.06%/h. The results from degradability show that PKC fiber was highly available to the animal, with better feed value than the grass silage (Table 1) and agreed with those found in the literature (Settineri et al., Reference Settineri, Pace and Catillo1994). Emptiness, using the ball technique, shows high levels of gas fraction at 60% of PKC therefore requiring further investigation for gas quality. The current study concluded that the best level of inclusion for PKC is 60%.
