ABSTRACT
The objective of the present study was to study the influence of replacing concentrate feed mixture (CFM) with different levels of corn steep liquor (CSL) at the rates of 10, 20, and 30% on the basis of crude protein supply in diets. Twenty four Zaraibi does, at the beginning of pollination season (flushing period), weighing 37.5 kg and aged < 30 months, were selected from El Serw farm and divided into four similar groups (n=6/group). The groups were assigned at random to receive the four experimental rations. All goats offered treatment diets 30 days before the breeding season as flushing period then through pregnancy and lactation periods. Dietary effects on average birth and weaning weights, total body gain and daily body gain of kids, kilogram kids born, kg kids weaned/does, mortality rate of kids, and economic efficiency were studied. Total and daily milk yield (34weeks), total solids, fat, total protein, lactose, ash and pH value were measured for milk. Average daily feed intake from CSL, CFM, roughage, total DM intake, DM intake (g/kg w0.75) and feed utilization efficiency were studied. The results revealed that productive and reproductive performance of dairy Zaraibi goats were affected by using CSL. It seems that cases of twins and litter size was more . The greatest value of litter size was recorded with Tr1 (control) (2.5) and the lowest value (2.17) was recorded with Tr2 (10% CSL) and Tr4 (30% CSL). But, Tr3 (20% CSL) recorded medium value (2.33). Meanwhile, birth and weaning weights were higher in Tr2 (1.77 and 12.46 kg) than Tr1 (control) (1.57 and 9.58kg, respectively). The same trend was observed also with kilograms produced per doe which was greatly better with CSL in Tr2 and Tr3 (20.6 and 20.67, respectively) compared with the other groups. However, the percentage of mortality recorded the highest value in Tr4 (22.22%) then Tr1 (13.89%) followed by Tr3 (8.33%), while mortality rate was zero in Tr2. Data of daily milk yield, was significantly reduced with Tr1(1.00 kg/h) compared with Tr2 (1.30 kg/h),Tr3 (1.210 kg/h) and Tr4 (1.380 kg/h). Also, total milk yield was reduced with control group (238kg) by 13.0, 21.0 and 37.8% compared with Tr2 (269kg), Tr3 (288kg) and Tr4 (328kg) and the differences were significant. Total solids (TS) milk, fat, protein and lactose were significantly influenced by the tested treatments. The lowest values (P≤0.05) of TS, protein and lactose were recorded with control ration (11.83, 3.02, 2.86 and 4.63%, respectively). The data of milk quality indicated that PH value was higher (6.77) with control group compared with the other three levels of CSL (6.61, 6.67 and 6.67 for Tr2, Tr3 and Tr4, respectively). Based on results of the present study, it could be safely concluded that replacing CFM with CSL in Zaraibi does rations resulted the better productive and reproductive performance and feedlot performance.