Effect of starch source in diets contained corn steep liquor on performance, blood metabolites, and ruminal enzymes activities of fattening lambs

Corn steep liquor (CSL) contains high amount of protein (42% DM basis) which is high in soluble protein ratio. This feedstuff is derived from the corn processing and has contain relatively high concentration of soluble protein. Despite previous studies evaluated the inclusion of CSL as protein source in diets, but synchronized inclusion of this feedstuff with different energy sources (starch) need more research. The effects of synchronization of CSL with different starch containing sources (barley, corn and wheat) on performance, blood metabolites and ruminal enzymes in Farahani fattening lambs was evaluated.
Eighteen Farahani lambs averaging BW 32 ± 3 kg (SD) were allocated in three different experimental treatments (6 lambs/each) in completely randomized design in a 9 weeks fattening trial. The basal diet has contained similar amount of CSL (10% DM basis) and different starch source was offered in different experimental treatments as follow; 1) barley grain (BG); 2) corn grain (CG); and 3) wheat grain (WG). Other dietary ingredients were constant among treatments.
The results showed that the feed intake (P = 0.01) as well as daily gain (P = 0.05) differed among treatments with the greatest amounts of both intake and gain for corn grain fed lambs. Conversely wheat grain fed lambs showed the lowest intake and gain in the current study. The feed conversion ratio was constant among treatments. The corn fed lambs had the greatest ruminating time in the current study. The CG fed lambs had tended to have greater glucose (P = 0.09), however lower BHBA (P = 0.03) concentration in blood. Feeding barley grain with CS resulted the greatest urea nitrogen concentration in blood (P = 0.01). The rumen pH was reduced in barley fed lambs and the greatest ruminal pH value was obtained in lambs fed corn grain. No one of the measured ruminal fluid enzymes (CMCase, MCCas) were differed among treatments.
In conclusion, results revealed that inclusion of CSL as high soluble protein source is more efficient if synchronized with corn grain in comparison with barley or wheat grains in fattening lamb production.