Effects Of Enzyme Complex On Growth Performance,Nutrient Utilization, Calcium And Phosphorus Metabolism Of Ducks

This paper was conducted to investigate the effect of an enzyme complex on the growth performance, carcass properties, digestive organs development, nutrients availability, calcium and phosphorus metabolism of ducks fed on reduced density of dietary nutrition.Experiment1:Effects of Enzyme Complex in Different Nutrient Levels of Diets on Growth Performance, Digestive Organs Development, Calcium and Phosphorus Metabolism of DucksA total of640day-old male Cherry Valley ducks were randomly allocated into5treatments according to a randomized complete block design. Treatments included: positive control PC (PC), two negative controls:NCI (PC-ME334.40kJ/kg-2.0%DAA-AP0.15%-Ca0.10%) and NC2(PC-ME418.00kJ/kg-2.5%DAA-AP0.20%-Ca0.15%), and with or without enzyme supplementation. PC, NCI and NCI+Enzyme had10replicates per treatment, whilst NC2and NC2+Enzyme contained5replicates per treatment, each replicate contained16ducks. This study included two phases:starter (1-21d) and grower (22-35d). The result showed as followed:1) Compared with PC, NCI decreased growth performance and tibia Ash, P and Ca contents (P<0.01), and increased mortality (P<0.01); NC1decreased serum Ca and P contents at day35, and serum Ca at day7, increased serum ALP activity at day35(P<0.01). In addition. NCI significantly decreased breast muscle rate, abdominal fat rate, dietary AME, TME and energy availability (P<0.01). NCI increased the relative length of digestive tract and the relative weight of liver, stomach and cecum at day35(P<0.05). NCI decreased jejunum villus height(VH) at day21, and duodenum crypt depth(CD) at35d of age(P<0.01). 2) Compared with PC and NC1, NC2further reduced growth performance and tibia Ash, P and Ca contents. Compared with PC, NC2decreased serum Ca content at day7and21, and decreased serum P content at day7(P<0.05). After day21, ducks of NC2all dead.3) The enzyme supplementation to both NCI and NC2increased BW, BWG and FI (P<0.01), and reduced mortality (P<0.05). NC1with enzyme supplementation increased tibia Ash, P and Ca contents (P<0.01), and serum P content at day35(P<0.05). In addition, NCI with enzyme supplementation increased breast muscle rate(P<0.01) and abdominal fat rate(P<0.05), and decreased the relative length of digestive tract and the relative weight of liver, stomach and cecum at day35, and increased duodenum VH/CD at day21and duodenum VH at day35(P<0.05).Experiment2:Effect of Enzyme Complex in Low Nutrient level of Diets on Growth Performance, Nutrients Availability, Calcium and Phosphorus Metabolism of Ducks560day old male Cherry Valley ducklings were randomly allocated into5treatments (7replicates/treatment,16ducklings/replicate), according to a randomized complete block design. Treatments included:positive control (PC), two negative controls:NCI (PC-ME292.60kJ/kg-2.0%DAA-AP0.10%-Ca0.10%) and NC2(PC-ME418.00kJ/kg-2.5%DAA-AP0.15%-Ca0.12%), and with or without enzyme supplementation. The result showed as followed:(1) The enzyme complex was effective in improving (P<0.05) live weight (LW), live weight gain (WG)(P<0.05) and feed intake (FI)(P<0.05) in the whole experiment period, and the enzyme responses in increasing LW and WG were greater for diets with reduced AP and Ca.(2) Utilization of dietary DM, EE, Ash, P and Ca was significantly improved (P<0.05) by the enzyme addition. Meanwhile, AME and N utilization were improved (P<0.05) in NC2+E.(3) Serum ALP activity, Ca and P concentrations were not affected by the dietary treatments, but serum P concentration at35d was increased (P<0.05) in NC2+E. The enzyme supplementation to the NC diets improved (P<0.05) tibia ash, Ca and P concentrations and restored to the level of the PC diet at35d. Tibia ash and Ca of NC2+E remained below the level of PC at14d. (4) Enzyme supplementation to NC diet had no significant effect on carcass properties, the relative length of digestive tract and the relative weight of digestive organs (P>0.05).These results suggest that the AP deficiency was the primary cause of performance losses following the down-spec of all major nutrients, and decline in feed intake was the first sign of impairment. The supplementation with the enzyme complex containing carbohydrases and phytase effectively alleviated the negative effects from the reduction of AP, energy, amino acids of ducklings.