Abstract
Availability of feed crops for animal production is decreasing, creating a need to identify alternative food sources. With their high protein content, mulberry leaves are a likely candidate for feed supplementation and have been trialed on pigs and chickens, but little is known about their effect as a feed supplement on geese. Here, we determine the nutritive value of mulberry leaf meal (MLM), measure the digestibility of energy and amino acid of MLM in male Sichuan white geese, and evaluate the performance of these geese fed an MLM-supplemented diet. The composition of MLM was as follows: gross energy 4.94 Mcal/kg, crude protein 18.81%, ether extract 11.65%, crude fiber 12.45%, calcium 2.46%, phosphorous 0.24% and amino acids 0.26-1.92% (all % on a dry matter basis). Using the emptying then force-feeding method on 24 geese aged 194 days, we measured the apparent metabolizable energy of MLM as 1.58 Mcal/kg (on a dry matter basis), and the true total tract digestibility of the amino acids in MLM as 50.54-79.98%. We then randomly allocated a further 210 geese aged 35 days to one of five dietary treatments (control diet alone or supplemented with 4%, 8%, 12% or 16% MLM). Each treatment contained six replicate pens of seven birds per pen, and birds were maintained on their treatment until 70 days of age. Geese fed diets containing MLM exhibited lower weight gains, elevated feed consumption and an increased feed to gain ratio (P<0.05) compared with geese fed the control diet. Moreover, geese fed diets supplemented with MLM all experienced diarrhea, reduced amounts of subcutaneous fat and lower percentages of skin and abdominal fat (P<0.05) compared with control geese. In conclusion, MLM should be used with caution as a feed supplement for geese.