摘要：The effect of nutritional flushing for a period of six weeks prior to mating on the physical condition, serum metabolic and hormonal status at mating and litter size at birth of 32 pluriparous West African Dwarf (WAD) goats was studied using a 2 x 2 factorial design. The factors in the design were age (young, 3-4 years old versus old, 5-6 years old) and nutritional flushing regime (pasture alone versus pasture plus concentrate supplementation). The young does gained more weight and body condition (2.0±0.30 kg; 0.53±0.10 units; p>0.05) over the 6-wk nutritional flushing period than the old does (1.4±0.30 kg; 0.40±0.10 units), but the old does were heavier (p<0.05) at mating. The overall mean (±SE) total serum protein was 86.1±0.76 g/l at mating and did not differ (p>0.05) between treatments. The serum glucose concentrations were also similar for the treatment groups and averaged 2.6±0.10 mmol/l at mating. At the end of the nutritional flushing period, supplemented does had a higher (p<0.05) serum concentration of insulin (19.1±0.63 versus 15.1±0.63 IU/ml) than the unsupplemented does. Young does also had higher (p<0.05) serum insulin concentrations (19.8±0.63 IU/ml) than old does (14.3±0.63 IU/ml). Serum Luteinizing Hormone (LH) concentration at mating was similar for supplemented and unsupplemented does, but was higher (p<0.05) for young does (11.8±0.23 < mu>IU/ml) than for old does (1.8±0.23 IU/ml). Young does had a higher litter size (1.81±0.12) than old does (1.50±0.12) and supplemented does had a larger litter (1.81±0.12) than the unsupplemented does (1.50±0.12). These differences were, however, not statistically significant (p>0.05). There was, however, an interaction between age of doe and nutritional flushing treatment with young does that were supplemented having a mean (±SE) litter size of 2.13±0.18 compared to 1.50±0.18 for each of the other three treatment groups. It was concluded that young (3-4 years old) does may benefit from concentrate supplementation of wet season grazing, but that old does (5-6 years old) will not benefit from this supplementation if they are in moderate body condition six weeks before mating.
