Effect Of Different Levels Of Glucose Inclusion On Feed Intake And Nutrients' Digestion By Growing And Fur Exchanging Minks

Dietary carbohydrates are digested by various enzymes and absorbed in the form of glucose in thesmall intestine of mink. The effect of different levels of glucose inclusion in the diets on feed intake andnutrients' digestion in growing and fur exchanging minks was investigated.In ExperimentⅠ, 60 growing minks with similar age and weight, were randomly allocated into 5groups with 12 animals in each group. One group was fed a basal diet (Diet 1-1), other groups were fedthe basal diet in which the extruded corn meal was substituted by 8.88 (Diet 1-2), 17.77 (Diet 1-3),26.65 (Diet 1-4) and 35.53％(Diet 1-5) of glucose. Corn gluten was also added to the later diets to form5 iso-nitrogenous diets. The experimental animals were weighed every 10 days and the weight changeswere recorded.In ExperimentⅡ, 55 fur exchanging minks with similar age and weight, were randomly allocated into5 groups with 11 animals in each group. One group was fed a basal diet (Diet 2-1), other groups werefed the basal diet in which the extruded corn meal was substituted by 8.77 (Diet 2-2), 17.54 (Diet 2-3),26.31 (Diet 2-4) and 35.09％(Diet 2-5) of glucose. Corn gluten was also added to the later diets to form5 iso-nitrogenous diets. After the feeding trial, the animals were killed and the length weights of fur andthe subcutaneous fat were measured.The results of ExperimentⅠshowed that as the levels of glucose inclusion increased, dry matter (DM)intakes, and the nutrient intakes such as organic matter (OM), crude protein (CP) and crude fat (EE) bythe experimental animals decreased (p＜0.05), the digestibility of nutrients tended to increase, whiledigestible nutrients' intake were not significantly affected (p＞0.05). Digestible energy (DE) intakes didnot differ significantly among dietary treatments, being 0.63, 0.61, 0.64, 0.62 and 0.69 MJ/d for diets1-1, 1-2, 1-3, 1-4 and 1-5, respectively. Urine excretion was significantly increased with increasinglevels of glucose addition (p＜0.005). The weights of experimental animals were slightly reduced asglucose inclusion. The reason for reduced feed intake and live weight of minks when their dietssupplemented with glucose is probably because that the glucose in the diets was rapidly absorbed in thesmall intestine leading to the increase of blood glucose level after meal, this stimulated the satiety centerin the hypothalamus, thus the animals stopped feeding. The reduced feed intake resulted in lighter liveweights. The increase of urine excretion with increasing levels of glucose inclusion in the diets isprobably because that blood glucose levels surpassed the kidney threshold for glucose due to its rapid absorption, and the excessive glucose was excreted from the urine, thus increasing water intake andurine excretion by the animals.The results of ExperimentⅡshowed that DM intake was decreased, but DM digestibility wasincreased with glucose inclusion, thus digestible DM intake being similar among different treatments,especially for Diets 2-2, 2-3 and 2-4, the differences between them being within 1g. Digestible DMintakes for Diets 2-1 and 2-5 were slightly but not significantly higher than those for Diets 2-2, 2-3 and2-4. DE intakes were also very close, being 1.26, 1.21, 1.20, 1.24and 1.33MJ/d for Diets 2-1, 2-2, 2-3,2-4 and 2-5, respectively.The results of the two experiments indicated that mink has the ability to regulate its feed intakeaccording to dietary DE contents as shown in the trials that when glucose was included in the diets toincrease dietary DE levels, it reduced feed intake to maintain its energy balance. In the experimentalconditions in which iso-nitrogenous diets were used reduced feed intake resulted in reduction of CPintake, thus reducing weight gain of the experimental animals. Iris suggested that much attention shouldbe paid to the ratio of the energy and protein when preparing mink diets, i.e., digestible protein levelshould be simultaneously increased when digestible carbohydrate level is increased to meet both the-energy and protein requirements of mink.