The effect of guar meal (germ fraction) and β-mannanase enzyme on growth performance and plasma lipids in broiler chickens
A completely randomized design experiment was conducted to assess the effect of β-mannanase enzyme on a commercial broiler chickens strain fed with different levels of guar meal germ fraction (GM) Each treatment was assigned to 4 replicate for a total of 24 pens, consisting of 15 chicks per pen, in randomized complete block design. Experimental groups include: control diet without GM, low level of GM (2, 4 and 6% in starter, grower and finisher diets respectively), intermediate level of GM (4, 6 and 8% in starter, grower and finisher diets respectively), intermediate GM+β-mannanase enzyme, high levels of GM (6, 9 and 12% in starter, grower and finisher diets respectively) and high GM+β-mannanase enzyme. Body weight gain (BWG), feed intake (FI) and feed:gain ratio (F:G) were measured weekly. At the end of the experiment (42 day of age), blood samples were collected for the determination of plasma triglycerides, totalcholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL) and then the chicks were killed for carcass dressing. BWG, FI, F:G ratio and plasma lipids were affected by experimental groups (P<0.05). Experimental groups had no significant effects on relative weight of carcass and relative weight of giblets except for abdominal fat (P>0.05). In the control, low GM and intermediate GM+β-mannanase groups, BWG, FI, F:G ratio, relative weight of carcass and giblets and plasma lipids were better than other treatments. High GM in broilers diet deleteriously affected growth performance, FI, F:G ratio and plasma lipids. Result indicates that optimal levels of guar meal are low level without β-mannanase and intermediate level with β-mannanase without adverse effects on growth performance or plasma lipids of broiler chickens.
Keywords: Guar meal, β-mananase, plasma lipid, performance, broiler chicken