Use of pre-germination of grains and oilseeds to improve feed value and gut development in broiler chickens
It is hypothesised that chemical processes that activated when seeds germinate have a beneficial effect on nutrient availability to broiler chickens and feed efficiency.
The aims of optimal germination procedures of both grains and oilseeds were to maximise endogenous seed enzyme activity and reduce antinutritional factors. The data indicate that pre-germination lowered digesta viscosity, and improved digestibility and apparent metabolisable energy (AME).
The use of exogenous enzymes, balanced diets, in-feed antimicrobials and feed processing techniques enable birds to ingest, digest, absorb nutrients more effectively.
The industry is interested in new and, in the case of in-feed antimicrobials, alternative additives and processes to increase feed value of ingredients and health of birds.
Previous research by Scott and Campbell (1998) demonstrated that pre-germination techniques applied to wheat and barley significantly improved feed intake and growth without a significant effect on energy availability.
Optimal germination procedures in terms of increasing feed nutrient utilisation would therefore be considered as a viable 'natural' (green technology) alternative feed processing treatment for broiler chicken production.
The germinated (0 or 21 h) canola, sorghum and wheat were used to produce six diets; each was fed with (0.0 or 0.5 g/kg diet) supplemental enzyme (Phyzyme (phytase) and Avizyme 1302 (xylanase + protease); Finnfeeds Ltd, Marlborough, UK.
The 12 diets and water were provided ad libitum to four pens of six male broilers from 0 to 21 d of age. Individual bird weights were recorded at 0, 7, 14 and 21
At day 21, digesta was recovered from the upper small intestine (end of duodenum to MeckelÂ¡Â¯s diverticulum) of each of the 48 birds to determine digesta viscosity.
Chickens fed canola-based diets recorded significantly higher relative gizzard, breast muscle and caecum length values than both sorghum- and wheat-based diets at 21 d.
Additionally. significantly higher body weight and feed intake and conversion values were recorded from chickens fed canola-based diets compared to both sorghum and wheat diets at 21 d.
Enzyme addition had a significant positive effect on both body weight and feed conversion ratio at 21 d across all grain-type diets.
Enzymes significantly reduced digesta viscosity in both canola and wheat diets but not sorghum-based diets.
Digestibility, AME and ME efficiency values were all significantly lower in canola-based diets compared to both sorghum and wheat diets.
There was a positive effect of germination when canola seed was germinated and included in a broiler starter diet at 25% of the diet. Whereas, there was no significant effects of germination on sorghum diets (75% sorghum inclusion) and a reduction in growth of broilers fed germinated wheat-based diets. This would indicate an overriding positive effect of germination of canola seed.
The lack of response of sorghum-based diets to germination treatment is perhaps indicative of a failure of the specific germination conditions applied here to invoke biochemical changes within this grain type in the time span allowed (21 hours).
The consistently negative influence of germination treatments on performance characteristics on broilers fed wheat-based diets conflicts with previous work performed by Scott and Campbell (1998).
However, the germination procedure in their work utilised more sophisticated equipment to enable unimpeded water uptake, access to oxygen and thus a uniformly pre-germinated product. Additionally their germinated product was ground to a mash whilst wet (germinated) and then dried, possibly allowing greater enzymatic and phytochemical access (from the aleurone layer) to endosperm and thus more complete breakdown of antinutritional factors.
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Article made possible through the contribution of the Australian Poultry Science Symposium (APSS) 2006.