Nutrition Responses of Rats Fed Mixtures of Plant and Animal Proteins
Twenty four male rats (45-65g) were used to determine the nutritional responses to mixed plant and animal protein diets. Rats were fed various mixtures of sorghum (S), pigeon pea (PP). bread fruit (TAP) plus crayfish (CR) to provide 1.6g N/100g of daily diet for a
35-day study period. Three different diets were fed to 6 rats assigned to each diet on the basis of body weight. Combination of PP:CR caused increases in N intake and retention, weight gain, and PER higher than for those of the other test groups. Its values for N intake and retention, and BV were higher than for those of the control except for food intake, NPU, weight gain and PER. Substitution of CR (20%) with TAP and PP as supplements to S decreased food intake, weight gain and PER and increased N intake. digested and retained N,
NPU and BV.
The results appear to indicate that (a) PP:CR blend was better than other blends as judged by the parameters, and (b) TAP and PP were superior to CR alone as supplement to S.
The fight against protein malnutrition the world over is based on bridging the gap between protein needs and supplies. As a result, it has become a special task of nutrition research to develop and test nutritionally adequate diets from commonly consumed foodstuffs, locally and readily available, cheap, and acceptable to the population groups [l]. The development and test of diets based on commonly consumed foodstuffs have been receiving considerable attention in this laboratory. Among the several types of cereals commonly consumed in Nigeria is sorghum bi-color.
It provides an important staple diet in northern Nigeria where it is the principal food crop 121. About 5O0/0 of the total area devoted to cereal crops in Nigeria is used for the cultivation of sorghum. Presently, 95% of Nigerian sorghum production is consumed as human food with differential preference for certain varieties . Compared to casein or other well balanced protein sources: the relative nutritive value of sorghum protein is low . Wall and Blessin  have shown that the sorghum protein is low in lysine, tryptophan, and threonine than human requirements like those of other cereals. For a more balanced diet sorghum food must be supplemented with other
foodstuffs which are rich in the deficient amino acids.
Legume foods are ideal complement to sorghum food. They are rich in lysine, threonine, valine, and other essential amino acids (EAA) 161. Legumes are also good sources of thiamine, riboflavin, iron, and calcium [7, 81. Thus, the simultaneo~s~ingestioonf cereals with legumes and cheap animal protein like crayfish has a complementary effect and offers a technique for improving protein nutrition within the economic and cultural patterns of families. The practice of eating cereals in conjunction with legumes is very common in Nigeria, however, the methods of preparation, particularly legumes are inadequate.
This may have some important nutritional consequences for the vulnerable groups, mostly the children. Breadfruit (Treculia africana) is a tree legume locally called “ukwa”. It is a popular traditional food amongst the Igbos of the Southern part of Nigeria. The seed grains are consumed only among the Igbos.
Very little information is available in the literature on its chemical compositon in relation to its nutritive value and possible application in food processing . Makinde et al.  observed that “ukwa” seed grain appears to be low in sulfur containing amino acids (SAA) while it is fairly high in aromatic amino acids when compared to provisional FAO/WHO requirements [lo]. However, its SAA are higher than for most pulses [l l].
The protein content of 19% of the defatted meal compared favourably with that of most pulses (22%) an indication that the protein could be employed favourably in mixed diets . In Nigeria, pigeon pea (cajanus cajan) is consumed alone sometimes and at other times with cereals or cheap animal protein like crayfish (Astacus Fluviatilis). Crayfish is generally used as a food condiment and at times cereals and legumes are consumed locally in combination with it as the only animal protein within the reach of everybody in this part of the country. In
some parts of Southern Nigeria, however, it forms the main source of dietary protein .
The crude protein content of crayfish has been shown to be within 60-70%. However, few, if any, works have been done to evaluate the supplementary value of crayfish. Obizoba [I 31 recently observed that at 20% supplementation of rice protein with crayfish produced protein
that was comparable to casein as judged by growth. It was reported that above this level (20%) brown bean protein was superior to crayfish as a supplement to rice protien. The major objectives of the present study were to evaluate the supplementary value of crayfish to sorghum and pigeon pea alone and replacement of CR with TAP and PP as supplements to S.
Growth, food and nitrogen (N) intakes, digested and retained N, weight gain, PER of rats were the criteria of evaluation selected for use.
Nutrition Responses of Rats Fed Mixtures of Plant and Animal Proteins
Materials and methods
Animu1.r md housing The 35-day investigation included a 28-day growth period followed by a 7-day N balance period. Twenty four male albino weanling rats 45-65 g whose supplier has been cited previously  were divided into four groups of six rats each on the basis of body weight. The rats were weighed prior to being allotted in other control and their respective test diets dnd at weekly intervals until the end
of the investigation to establish weight changes.
The animals werehoused in individual metabolism cages and fed diets and water ad libitum for 35 days. The cages were of the type previously described . The sorghum, pigeon pea, African breadfruit (Treculia africana), and crayfish were purchased from local retailers. The sorghum grain (S) was boiled for 90mins in a 1 :3 water after sorting to remove extraneous materials.
When the grains were soft enough for consumption they were removed from fire and there were little or no cooking water left in the cooking utensil. The pigeon pea (PP) was treated as S and cooked for 130mins. The African breadfruit (TAP) was bought already dehulled and cooked for 50 rnins when it was soft for consumption.
The crayfish (CR) (Astacus spp) was dried in an oven at 95’C for 20mins and then ground into a fine powder in a laboratory hammer mill (70-mesh screen). The boiled grains were then dried separately to 99% dry matter in an oven at 85’C for 8 h and then ground into a fine powder using the same machine and screen size as for crayfish. Table 1 presents the ingredient composition of the experimental diets.
The control diet contained casein as the sole source of protein. The three test diets had 80% of their protein from S and PP and the remaining 20% from CR alone or 10% each from TAP and PP. These three diets regardless of protein source were isonitrogenously formulated to provide 1.6g N daily (10% protein) for the entire study period.
Another group of rats were fed regular rat chow for 28 days and then switched over to a N-free diet for 7 days. After a 2-day adjustment period, the urine and feces collected from this group were analyzed for total N.