As shown in Table 4, the values for the one-step measured IVDMD1 ranked as follows: CLR>LCSH> DCSH (p<0.05).
Ammonia N concentration showed no differences between LCSH and CLR, and the lowest ammonia N concentration was found for DCSH (p<0.05).
The maximum gas production 'a+b' value was similar between CLR and LCSH, but their means were greater than the mean for DCSH (p<0.05).
In the present study, the CP contents of DCSH and LCSH were close to literature values reported for the lower limit (40 g/kg DM) and upper limit (124 g/kg DM), respectively, for cottonseed hulls (Hsu, 1987; Garleb, 1988).
In the present study, the ME value for CLR was greater than that determined for LCSH and almost twice that found for DCSH. The ME content of CLR was close to previously estimated ME contents of whole cottonseed and soybean meal (Getachew et al., 2002; Granger et al., 2010) and was at least 20% higher than that reported for corn silage, alfalfa hay and fresh napier grass (Lee et al., 2000).
In the present paper, the in situ and in vitro trials indicated a greater digestibility and fermentability of CLR than was seen for either LCSH or DCSH. This suggests that the ruminal degradation rate for the CSBPs should correlate positively with the ratio of kernel content to short linter.
In the present study, both in situ and in vitro ruminal degradation of DM and CP were greater for LCSH than for DCSH, which suggests that short linters are more readily degraded in the rumen than are long linters.
In the present study, a faster degradation rate was observed for CLR than for either LCSH or DCSH. No apparent differences were observed for ammonia N in the three CSBPs.
In the present study, total VFA production was markedly lower for DSCH than for CLR, which might be a consequence of the presence of higher amounts of hull associated structural fibre in DCSH than in CLR.