Maize-based diets

Maize is low in vitamins but contains useful amounts of biotin and carotenoids. Niacin is present in a bound form and together with a low level of tryptophan, a niacin precursor, leads to this vitamin being particularly limiting in maize-based diets unless supplemented. 

Earthworm meal has also been shown to be a useful protein source for Japanese quail. Das and Dash (1989) fed 1-week-old male and female Japanese quails on a maize-based diet containing 60g/kg fishmeal or 60g/kg earthworm meal. After 56 days, total weight gain was 96.1 and 98.5 g, feed intake was 533 and 511 g and feed conversion ratio 5.54 and 5.19g/g for the control and earthworm diets, respectively. Egg quality was not influenced by the diets. 

Davis (1978) describes a group of Yucatan inhabitants who use coffee extensively and who are relatively insensitive to PTC. He argues that insensitivity to bitter substances may confer a survival advantage in that roasted coffee contains therapeutic levels of niacin, which is generally deficient in corn- or maize-based diets. Cultures with maize as the dominant dietary staple often evidence pellagra, since corn has a low tryptophan content. Interestingly, as reviewed by Katz (1982), some cultures have developed food preparation practices which help to overcome this problem. 

Deficiency diseases pellagra (from the Italian rough skin ) occurs if diet Is deficient in BOTH niacin and tryptophan such as maize-based diets (dermatitis, diarrhoea, dementia)... 

For optimal performance the diet must provide adequate amounts of EAA, adequate energy and adequate amounts of other essential nutrients. The CP requirement values outlined by the NRC (1994) assume a maize/soy diet, of high digestibility. It is advisable to adjust the dietary target values when diets based on feedstuffs of lower digestibility are formulated. The bioavailability of EAA in a wide range of feedstuffs has been measured by... 

Based on a maize/soy diet. Some values in the above table were stated as being tentative. 

Murphy, J.J., Connolly, J.F., McNeill, G.P. 1995. Effects on milkfat composition and cow performance of feeding concentrates containing full fat rapeseed and maize distillers grains on grass-silage based diets. Livestock Prod. Sci. 44, 1-11. 

Iron availability is low in rice and maize-based phytate-rich Third World diets, and blood losses due to hook-worm infections are frequent in these countries. Iron deficiency is the most widespread micronutrient deficiency besides vitamin A and iodide. The prevalence of iron deficiency may be as high as 60% in Third World pre-school children, and almost half of these children (26%) show iron-deficiency anemia (Romero-Abal et al. 1995). However, about half of the even higher prevalence for anemia of up to 70% in African women and children (Quar-shie and Amoaful 1998) seems attributable to inflammation and parasitic infections (Asobayire et al. 2001) and other micronutrient deficiencies, rather than to iron deficiency (Allen et al. 2000). Hypochromic microcytic iron-deficiency anemia reduces physical work capacity, and both show a close correlation (Dallman 1982). As the brain is luxuriously perfused with blood, impairment of intellectual performance in anemia is a very variable symptom. Anemia at an age of 12-18 months seems to compromise the infant s intellectual development. To what extent such deficits in intelligence can be compensated during later development at adequate iron supply levels has been discussed, somewhat controversially, by Walter (1993) and Pollitt (2001). 

Furuya S., Kaji Y., 1991. Additivity of the apparent and true digestible amino acid supply in barley, maize, wheat or soya bean based diets for growing pigs.An/m. Feed ScLTechnoL, 32,321-331. 

The protein contents of various fishmeals vary over a range of about 500-750 g/kg, but the composition of the protein is relatively constant. It is rich in the essential amino acids, particularly lysine, cystine, methionine and tryptophan, and is a valuable supplement to cereal-based diets, particularly where they contain much maize. The essential amino acid composition is compared with that of ideal protein (see Table 13.7 in Chapter 13) in Box 23.3. 

Amaya-Guerra, C., Alanis-Guzman, M.G., and Sema-Saldivar, S.O. 2004. Effects of soybean fortification on protein quality of tortilla-based diets from regular and quality protein maize. Plant Foods Hum. Nutr. 59(2) 45-50. 

---