Quality - protein maize (QPM) as a feed ingredient for layer chickens

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A feeding trial was conducted in two phases, using 300 eight-week old Shaver Starcross 579 chicks to study the effect of quality-protein maize (QPM) on their growth and subsequent laying performance. In the grower phase (8-19 weeks), five isocaloric diets comprising three QPM diets and two normal maize control diets were tested. The two normal maize diets designated high and low protein respectively contained 574g normal maize with crude protein (CP) content of 160g and 600g normal maize with 140g CP per kilogram of diet. The three QPM diets tested contained 570g QPM, 585g QPM and 600g QPM with dietary protein levels of 160g. 150g, and 140g per kilogram of diet respectively. Similarly in the layer phase (19-51 weeks), the five isocaloric diets tested comprised 565g normal maize with 150g CP, 595g normal maize with 130g CP, 560g QPM with 150g CP, 585g QPM with 140g CP, and 595g QPM with 130g CP per kilogram of diet. The completely randomised design (CRD) was used and each treatment was replicated four times. The initial average liveweight of the experimental birds was 575.8g. Feed and water were supplied ad libitiirn. QPM and normal maize grains, their by-products (bran, and bran-and-germ) as well as the experimental diets were analysed for their proximate composition. In addition, QPM, normal maize and the experimental diets were analysed for their essential amino acid composition and gross energy. The parameters measured included mean daily weight gain, mean daily feed intake, feed/gain ratio, feed cost, mortality, hen-day production, egg weight, shell thickness, and internal quality of eggs. The grains of QPM and normal maize had similar proximate composition. On the other hand, QPM contained 0.32g lysine and 0.08g tryptophan per 100g grain compared with 0.24g lysine and 0.06g tryptophan in normal maize. Also, leucine-isoleucine ratio of QPM was 3.0 and that of normal maize was 3.5. The bran of QPM comprised, on dry matter basis, 62.Sglkg crude protein (CP), 33.0glkg ether extract (EE), 166.4g!kg crude fibre (CF), 12.0glkg ash and 626.3glkg nitrogen-free extract (NFE) compared with 545.0glkg CP, 36.5glkg EE, 158.0g/kg CF, 9.5glkg ash and 631 .0g/kg NFE of normal maize bran. QPM bran-and-germ, also, consisted, on dry matter basis, of 175.0g/kg CP, 237.8glkg EE, 106.9glkg CF, 48.5glkg ash and 338.3gIkgNFE compared with 126.4glkg CP, 207.6g/kgEE, 108.8g/kg CF, 51.5g/kg ash and 409.7g!kg NFE of normal maize bran-and germ. In the grower phase, pullets fed the low-protein normal maize diet registered significantly (P<0.01) lower weight gain than the other birds. Mean feed intake and efficiency of feed utilisation were however not significantly (P>0.05) affected by dietary treatments. Feed cost was lowest (P<0.0l) for QPM diet, QPM2. This represented 17.4% reduction in grower feed cost compared with the feed cost of the high-protein normal maize diet. No mortality was recorded during this phase. In the laying phase, egg production was significantly (P<0.00l) depressed in hens fed either low-protein normal maize diet or low-protein QPM3 diet. Pullets given QPM2 diet laid their first eggs at mean age of 117 days (P<0.01), attained 5% egg production at mean age of 124 days (P>0.05) and 50% egg production at mean age of 130 days (P<0.05) all of which occurred a week earlier than the other dietary treatments. Egg quality measurements, feed intake, and feed conversion did not appear to be affected (P>0.05) by the dietary treatments. Feed cost was lowest (P<0.001) for QPM diet QPM2, representing a 10.3% reduction in layer feed cost compared with the feed cost of the high-protein normal maize diet. Based on the results obtained from this experiment, QPM is recommended in the feeding of layer chickens due to its superior protein quality, favourable nutritional effect on growth and subsequent laying performance as well as reduction in feed cost.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science in Animal Science, 1997