Nutritional manipulation of feeding behaviour of birds
A research to manipulate the feeding behaviour of laying hens from nutritional perspective was conducted with 504 ISA Brown. Seventeen (17) week old ISA brown with weights ranging between 1590 and 1812 g were allocated to six dietary treatments. There were seven replicates per treatment with 12 birds each making a total of 42 pens in all. Experimental diets differed in the levels of energy, levels insoluble Non Starch Polysaccharide (NSP) and the particle sizes of the NSP. Birds had free access to water and feed during which feeding observations with video camera were made to observe and record the feeding behaviour of birds at 17, 21, 25, 29, 33 and 35 weeks of age. A computer software programme called Observer 5.0 was used to analyze the observations by one person for 30 minutes per cage. In order to gain more insight in the feeding behaviour of laying hens, 60 laying hens were used for passage rate experiment using titanium dioxide as an inert marker. Five birds were used for each dietary treatment, and replicated twice. At t=0, three titanium capsules were offered to each bird. After five different time points (30, 90, 180, 270 and 360 minutes), these birds were sacrificed and dissected. The gut (titanium) contents from different segments of the GIT (crop, gizzard, ileum, colon and caeca) of each bird were analysed using spectrophotometer at an absorbance of 408 nm. Result from the study indicates that the feeding behaviour of laying hen can be manipulated nutritionally. Bulky diets (10.6 MJ/kg) significantly (P<0.05) increased the eating time of laying hens by 15% compared with normal energy content (11.8 MJ/kg) and this led to consumption of more feed (average 2355g) than those of normal energy diets (2175g). Similarly, the separate effect of NSP, NSP coarseness and interaction between low energy, NSP and NSP coarseness influenced the eating behaviour. Feeding layers with low density diet containing a combination of low energy high NSP coarse NSP increased the amount of time birds spent feeding by 32% and consequently increased the feed intake by 11% (average feed intake of 135g ) above normal energy low NSP mixture diet (average feed intake of 120g ). The passage rate experiment showed that Low energy High non starch polysaccharide coarse (LeHnspcoarse) diet reduces the gut transit time, thus birds quickly feel hungrier after a period of satiety, possibly resulting in a short inter-meal interval. Conclusively, the interaction between low energy, high NSP and NSP coarseness influence birds' feeding behaviour necessitating increase in eating time and faster passage rate via the GIT.
Keywords: Laying hen, NSP form, energy level, feeding behaviour and passage rate