Effect of replacing rapeseed cake with camelina (Camelina sativa (L.) Crantz) cake on nutrient digestibility, pancreatic enzyme activity, growth performance and carcass traits in fattening rabbits

The aim of this study was to investigate the effects of replacing rapeseed cake with Camelina sativa (L.) Crantz (CS) cake on nutrient digestibility, pancreatic enzyme activity, growth performance, and carcass traits in fattening rabbits. The control diet contained 100 g/kg rapeseed cake (RP); the second diet (CS50 diet) contained both RP cake (50 g/kg) and CS cake (50 g/kg); in the third diet (CS100 diet), the RP cake was fully replaced by CS cake (100 g/kg). A total of 168 Hyplus rabbits, weaned at 32 days of age and divided into three groups (56 animals per group; sex ratio 1:1), were fed one of the three experimental diets (between 32 and 74 days of age). In addition, 30 Hyplus rabbits (32 days old, 10 rabbits per diet; sex ratio 1:1) were used for the determination of the total tract apparent digestibility (CTTAD) of the diets and pancreatic enzyme activity (between 58 and 62 days of age). In rabbits fed the control diet a higher CTTAD of organic matter (on av. by 0.026; P = 0.044), crude protein (on av. by 0.026; P = 0.036), and acid detergent fibre (on av. by 0.060; P = 0.020), and a lower CTTAD of ether extract (on av. by 0.058; P = 0.001) were observed than in the other rabbits. There was lower proteolytic activity in the small intestinal contents of rabbits fed the CS100 diet than in those of other rabbits (on av. by 29.8 mg azocasein/g dry matter/h; P = 0.032). For the entire fattening period, the average daily weight gain (on av. by 2.3 g; P = 0.003), average daily feed intake (on av. by 6 g; P = 0.031), and final live weight (on av. by 122 g; P = 0.007) were lower in rabbits fed the CS100 diet than in those fed the other diets. Dressing-out was not affected by the dietary treatments. The relative weight of the liver (g/kg chilled carcass weight), however, was greater in rabbits fed diets containing CS cake than in those fed the control diet (on av. by 9 g; P = 0.002). The present study revealed that the inclusion of 50 g/kg CS cake in the diet of fattening rabbits had no detrimental effects on their health status or growth performance. In contrast, the negative performance results associated with the dietary inclusion of 100 g/kg CS cake indicated the necessity of determining the threshold level for CS dietary incorporation.