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Proximate, Mineral Compositions and Mineral Safety Index of Eight Organs of Guinea-Fowl (Numidia Meleagris) Emmanuel Ilesanmi Adeyeye Chemistry Department, Ekiti State University, Ado-Ekiti, Nigeria
[email protected] Abstract- The proximate and mineral composition as well as mineral safety index (MSI) of the organs of guinea-fowl (Numidia meleagris) were determined on a dry weight basis. The organs were: eyes, muscle, skin, heart, gizzard, brain, liver and the egg shell. The proximate values gave the following information (g/100 g): fat was low at 0.120 - 4.50; protein was generally high at 1.08-81.5; fibre was not detected except in the shell; carbohydrate was high at 5.46-98.3; energy was high at 1489-1707 kJ/100 g. The following minerals were reasonably concentrated in the samples: Na, K, Ca, Mg, Zn and Fe; Cu and Cr were not detected whereas P and Mn were only detected in some samples. In the MSI results, Na, Ca, Mg and P were within the MSI, Zn was outside MSI in two samples whereas Fe was within MSI in only one sample; no MSI was calculated for K, Mn, Cu and Cr. In the proximate, only fat and moisture were not significantly different in the proximate composition at α< 0.05 whereas Mn, Na/K, Ca/Mg and [K/(Ca + Mg)] were not significantly different among the minerals. KeywordsCompositions
Guinea-Fowl
I.
Organs; Proximate; Mineral
INTRODUCTION
Guinea-fowl birds are of four or five species, all in the family Numididae and all indigenous to Africa. Most of them have the speckled or pear-like plumage which can readily be identified in ancient representations of the bird, and very noticeably and beautifully in a painting by Pisanello (or one of his associates) which is often reproduced. The most important species by far, Numidia meleagris, is the bird here depicted. In Africa the various species of the guinea- fowl have ranges which collectively extend over the greater part of the continent south of the Sahara. They occupy a wide range of environment from the edges of the desert to the savannah lands (favoured by N. meleagris) and high forests. They have always had a reputation as crop robbers and this habit, bringing them into close contact, albeit of a competitive king, with humans may have contributed to their domestication. This probably took place in Africa and is likely to have associated with the introduction of keeping the domestic hen. Diffusion to Europe first took place from E. Africa, but there was subsequently a strong connection in this respect between Guinea in W. Africa and Portugal, which had a noticeable effect on the vernacular names given to the guinea-fowl in various languages. The Italian faraona is one of the few
linguistic vestiges of the old connection with Egypt [1]. Guinea-fowl birds were certainly known in ancient Egypt and in classical Greece and Rome. They appear quite often in Roman mosaics. However, comments by such authors as Varro and Martial suggest that up to the 1st century AD or later guinea- fowl were ‘still something of a rarity and the meat a special delicacy’. The quotation is from [2] whose monograph on guinea-fowl is a model of its kind and covers the historical aspect, all the way up to the 16th century. The classical world was also responsible for the legend which provides the specific name of the guinea-fowl, meleagris. The sisters of Meleager, the prince of Macedon who met an untimely death, are said to have wept so freely that they were transformed by a goddess into the birds, the pear-like spots on their plumage being their tears. The sisters then settled in island of Leros, off the coast of Caria; and it is in fact this island which, according to Donkin, provides the first clear evidence of guinea-fowl outside Africa. The generic part of the scientific name, Numidia, refers to the N. African country of that name in Roman times [1]. Eyes of certain animals and fish are considered a delicacy in some culinary cultures. In Laos the eyes of the giant cat fish of the Mekong are among the most highly esteemed parts of this highly esteemed fish. Examples could be multiplied, but the practice of eye-eating (even if cornea, lens and iris are removed, as in one unusual French recipe for Yeux de veau farcis) seems likely to contract rather than spread as the centuries roll by. Heart is an organ which is in almost all instances an edible part of an animal. Among the various sorts of offal, it is unusual in that it consists almost entirely of muscle. Moreover, the nature of the organ is such that the muscles are in constant use, pumping blood around the body, while the animal is alive; and hearts of older animals are therefore likely to be tough and to need marinating before being cooked. Hearts also have to be trimmed of fat and ‘pipes’ beforehand. Large ox hearts may be sliced and then grilled (broiled) if they are sufficiently tender; or, as more commonly happens, subjected to slow moist cooking, e.g. braising or stewing. Smaller ones are suitable for stuffing and then being baked. The smallest of all, such as hearts of rabbits are apt to turn up with the edible meat in a casserole
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dish or the like. Hearts of poultry and game birds count as giblets [1]. The bird stomach’s second chamber is known as the gizzard. The gizzard is tough and robbery when eaten. To accomplish what the gizzard does in the bird, it absolutely must be tough, for the gizzard’s major function is to grind and digest tough food consumed by the bird(http://www.backyardnature.net/birdguts.htm ). Brains especially those of calf and lamb, have been accounted a delicacy, valued mainly for their creamy texture. They can be poached in a court bouillon, or braised, or made into fritters. Poached brains in brown butter with capers are a popular dish in France, and something similar is well liked in Italy. In the 1990s marketing and consumption of calf’s (or cow’s) brains, together with some other organs, ceased in W. Europe because of fear that human beings might be affected by BSE (bovine spongiform encephalitis). Generally, brains are a very rich food, of which a little goes a long way. In regions like N. America, where attitudes of offal (variety meats) tend to be negative, the brains of slaughtered animals would be likely to finish up with members of immigrant ethnic groups. However, in most countries they are marketed and eaten without any special inhibitions [1]. Liver a relatively large organ in most animals, birds and fish, usually edible and in some cases delicious, although it has the unattractive function of secreting bile. Livers are appreciated in most parts of the world, although consumption is low in N. America. Calf’s liver is generally accounted the best among animals, because of the smooth texture and delicate flavour. Lamb’s liver is smaller but also delicate. Both these mild types of liver are suitable for being quickly sautéed, sliced or in larger pieces. Fegato alla salvia, calf’s liver cooked with sage, is well known in Italy, as is Fegato alla veneziana, with onions. Livers lend themselves well to the making of pastes, stuffings, sausages and the like. Liver dumplings, made from calf’s liver according to any of several good C. European recipes, are a real delicacy. Among the other ingredients which go well with animal livers are bacon, outmeal, sour cream, sharp apples, onions, shallots, garlic, marjoram and sage. Chicken livers are the most widely eaten of poultry livers, but the most famous are the specially fattened livers of goose or duck. Various game birds provide good livers, which may be served as special titbits on toast [1]. Egg shells, whether they are white or brown or speckled is immaterial to the cook. What does matter is that they are porous. One consequence of this is that eggs may absorb unwanted odours, a risk to which textbooks often call attention but which in practice seems to be slight. Another is that the carbon dioxide which begins to be formed within the egg as soon as it is laid can get out. Loss of carbon dioxide increases alkalinity and causes a slight diminution in the protein content of the egg. Egg processors prevent this by
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dipping their cleaned eggs in a special colourless and tasteless machine oil which seals the pores of the shell. By this means they also prevent another undesirable development, which is a gradual loss of moisture from within the egg and a corresponding increase in the size of the air pocket. They also, no doubt unwittingly, make it impossible to execute some kinds of egg cookery which are typical of the Middle East, notably ‘hamine’ eggs, in which whole eggs are simmered overnight, very gently, with oil and onions, whose flavour permeates the contents. A more exotic example is provided by Œufs à la constantinopolitaine, a recipe given by Mrs Level and Olga Hertley in 1925 [1], which calls for cooking eggs in their shells very slowly for at least 12 hours in a mixture of olive oil and Turkish coffee. The mixture eventually penetrates the shells, making the whites amber and the yolks orange and imparting a flavour of chestnuts. There is one recipe which is unusual in that it involves the consumption of the eggshells. It is given by Fernie [3], in the guise of a tonic: For delicate persons of all ages, the following preparation, which will contain egg shells in solution, has been found most singularly useful. Take six fresh eggs, six lemons, half a pound of castor sugar, and half a pint of white rum. Put the eggs in their shells inside a jar, without injuring the shells, peel the lemons, and, after removing their pith, squeeze the fresh juice over the eggs, then lay above them the rind and the pulp. Cover the jar lightly, and put it in a cool place for seven days, not forgetting to shake it well on each day. At the end of that time strain through muslin, when it will be found that the lemon juice has dissolved the egg shells. Add the sugar, and the rum; then bottle and cork it tightly. A wineglassful taken each morning before breakfast is the full dose, but at first it may be desirable to give only half this quantity. Since the shell of an egg, surprisingly, constitutes a tenth of the whole, and since it contains a lot of calcium and even a little protein, this can be represented as an economical procedure for those with access to a free supply of rum [1]. There are no across board reports on the chemical composition of the samples under report of the guinea-fowl organs. The evaluation of the amino acid profile of the yolk and albumen of guinea-fowl egg [4] has been reported. This study wants to report on the proximate and mineral compositions, mineral safety index (MSI); calculated values of proportion of total energy due to protein (PEP %), proportion of total energy due to fat (PEF %), proportion of total energy due to carbohydrate (PEC %) and utilizable energy due to protein (UEDP %); calculations of Ca/P, Na/K, Ca/Mg and the milliequivalent ratio of [K/(Ca + Mg)] [5]. II.
MATERIALS AND METHODS
The guinea-fowl used were two matured female birds. Prior to butchering, food was withheld for a day to help
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ensure the digestive system was empty. Head was held on the stump and the guinea-fowl’s head removed with an axe. At the end of bleeding, the guinea-fowl was plucked. When all the feathers were removed, the guinea-fowl’s anus was rinsed to remove any residue, then a sharp knife was inserted just below the hip bone without puncturing any of the internal organs. The guinea-fowl was removed, both skin and muscle sliced, rinsed and dried in the oven. The heart, liver and gizzard were also saved for the analyses. The gizzard was sliced into half until the gravel inside grates against the knife, then sliced around and opened up, peeling away the inner layer and discarding the contents, then rinsed out with cold water. Other parts analyzed in the head: eyes and brain were plucked out of the head and dried. Two eggs were used in which the shells were removed, rinsed and dried. The dried samples were ground, sieved and kept in freezer in McCartney bottles pending analysis. The micro-Kjeldahl method as described by Pearson [6] was followed to determine the crude protein. The crude fat was extracted with a chloroform/methanol (2:1) mixture using Soxhlet extraction apparatus [7]. Moisture, ash and crude fibre were also determined by the AOAC methods while carbohydrate was determined by difference. The calorific values in kilojoules (kJ) were calculated by multiplying the crude fat, protein and carbohydrate by Atwater factor of 37, 17 and 17 respectively. Determinations were in duplicate. The minerals were analysed from the solution obtained by first dry ashing the samples at 550oC. The filtered solutions were used to determine Na, K, Ca, Mg, Zn, Fe, Mn, Cu, Cr by means of atomic absorption spectrophotometer (Buck Scientific Model-200 A/210, Norwalk, Connecticut 06855) and phosphorus was determined colorimetrically by Spectronic 20 (Gallenkamp, UK) using the phosphovanado molybdate method [7]. All chemicals used were of British Drug House (BDH, London, UK) analytical grade. The detection limits for the metals in aqueous solution had been determined previously using the methods of Varian Techtron [35] giving the following values in µg/mL: Fe (0.01), Cu (0.002), Na (0.002), K (0.005). Ca (0.04), Mg (0.002), Zn (0.005), Mn (0.01), Cr (0.005). The optimal analytical range was 0.1-0.5 absorbance units with coefficients of variation from 0.9 % to 2.21 %. The coefficients of variation per cent were calculated [8]. Ca/P, Na/K, Ca/Mg and the milliequivalent ratio [K/(Ca + Mg)] [5]; the mineral safety index (MSI) [5] of Na, Mg, P, Ca, Fe and Zn were also calculated. The chi-square was compared with (Chi2T) setting the level of confidence at α < 0.05 [8]. III.
RESULTS AND DISCUSSION
Table 1 contains the proximate composition, energy values, the various energy values as contributed by protein,
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fat and carbohydrates. Crude fibre was detected only in the egg shells. The coefficient of variation per cent (CV %) was highest in the ash with a value of 120 % and lowest in energy distribution at 4.19. In the samples the chi-square (X2) results were not significantly different in the fat and moisture (it was not calculated in fibre) whereas all other parameters in Table 1 were significantly different at α < 0.05. Best results of each parameter were found as follows (g/100 g): ash (egg shell, 8.33), crude protein (muscle, 81.5), fat (heart, 4.50), carbohydrate (skin, 98.3), energy (kJ)(heart, 1707), PEP % (muscle, 86.1), PEF % (heart, 9.75), PEC % (skin, 98.6) and UEDP % (muscle, 51.6). The calculation of the organic matter (OM) gave values ranging from 91.67 g/100 g in the egg shells to 99.89 g/100 g in the skin. These OM values were higher in most cases than 98.97 g/100 g in ostrich muscles [9], 91.07 g/100 g in trunk fish [10] and the values reported for four fresh water fishes of Mormyrops delicious (86.4 g/100 g), Bagrus bayad (75.0 g/100 g), Synodontis budgetti (84.0 g/100 g) and Hemichronis fasciatus (76.0 g/100 g) [11]. The egg shells OM of 91.67 g/100 g was lower than literature values of the egg shells OM in francolin (94.2 g/100 g), duck (96.6 g/100 g) and turkey (92.4 g/100 g) [12]. The protein content of the samples (without egg shells) of muscle, heart, gizzard, brain and liver with value levels of 71.6-81.5 g/100 g were close to the value of 72.89 g/100 g reported for trunk fish as well as another report on trunk fish (74.5 g/100 g) [13]; 76.2 g/100 g (lean pork) and 72.5 g/100 g (lean meat of sheep) [14]; lower than 89.0 g/100 g (ostrich) [9]; close to 73.7 g/100 g (beef) [15] and lower than 87.2 g/100 g (chicken) [16]. Very low levels of crude protein were observed in skin (1.08 g/100 g), low in eyes (17.7 g/100 g). The value of 3.34 g/100 g (crude protein) in the egg shells was much lower than crude protein of literature values in francolin (73.1 g/100 g), duck (65.2 g/100 g) and turkey (71.9 g/100 g) [12]. However the present level of crude fibre in guinea-fowl egg shells (3.51 g/100 g) was much higher than the literature values of 0.04 g/100 g (francolin), 0.11 g/100 g (duck) and 1.14 g/100 g (turkey) [12]. The crude fat levels ranged from 0.12-4.50 g/100 g in the samples. From literature the value of fat in the muscle of turkey was 2.12 g/100 g and the skin of turkey was 12.1 g/100 g [17]; ostrich muscle (with skin) was 2.74 g/100 g [9], chicken muscle (with skin) was 12.6 g/100 g [16] and beef (22.3 g/100 g) [15]. The crude fat in egg shells was lower than in the egg shells from literature (g/100 g): 2.54 (francolin), 5.32 (duck) and 8.54 (turkey) [12]. The ash content was generally high in muscle (3.55 g/100 g), heart (2.35 g/100 g), gizzard (2.48 g/100 g) and highest in egg shells (8.33 g/100 g) with expected corresponding higher mineral levels in them compared with the other samples. Total ash in the egg shells was higher (8.33 g/100 g) than in (g/100 g): francolin (5.80), duck (3.44) and turkey (7.56). The energy levels in the samples ranged from 1.61-1.71MJ which were better than in turkey muscle and skin (1.33-1.37 MJ) [17], close to the levels in sheep lean meat (2.06 MJ)
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[14] and lean pork (2.29 MJ) [14]. The lower level of fats in present samples could have been responsible for lower levels of energy than in some literature results. The energy levels of 1.61-1.71MJ were better than 1.3-1.6 MJ/100 g from cereals [18] showing the samples to be reasonable sources of energy. Many samples had carbohydrate levels lower than 20.0 g/100
g (e.g. 5.46-16.6 g/100 g) whereas eyes (80.6 g/100 g), skin (98.3 g/100 g) and egg shells (81.0 g/100 g) had exceptionally high levels and this resulted into the skin being the second highest in energy concentration (1.69 < 1.71 MJ).
TABLE I PROXIMATE COMPOSITIONS OF VARIETY ORGANS OF GUINEA FOWL
Parametera
a
Eyes
Muscle
Skin
Heart
Gizzard
Brain
Liver
Egg Shell
Mean
SD
CV%
X2
TV
Remark
NS
Fat
0.250
3.55
0.120
4.50
2.10
1.25
1.30
1.50
1.82
1.53
83.9
8.96
14.07
Ash
0.130
4.06
0.110
2.35
2.48
0.210
1.03
8.33
2.34
2.80
120
23.5
14.07
S
Moisture
1.35
5.44
0.380
2.54
3.11
5.21
3.54
2.36
2.99
1.75
58.4
7.15
14.07
NS
Protein
17.7
81.5
1.08
74.9
71.6
76.7
73.6
3.34
50.0
35.8
71.6
179
14.07
S
Fibre
ND
ND
ND
ND
ND
ND
ND
3.51
-
-
-
-
-
-
CHO
80.6
5.46
98.3
15.7
20.8
16.6
20.8
81.0
42.4
37.3
88.0
230
14.07
S
Energy
1680
1610
1694
1707
1649
1632
1653
1489
1639
68.7
4.19
33.3
14.07
S
PEP%
17.9
86.1
1.08
74.6
73.8
79.9
75.7
3.81
51.6
37.0
71.6
186
14.07
S
PEF%
0.550
8.16
0.260
9.75
4.71
2.83
2.91
3.73
4.11
3.37
81.9
19.3
14.07
S
PEC%
81.6
5.77
98.6
15.6
21.4
17.3
21.4
92.5
44.3
39.2
88.5
243
14.07
S
UEDP%
10.7
51.6
0.650
44.8
44.3
47.9
45.4
2.29
31.0
22.2
71.5
111
14.07
S
PEP = Proportion of total energy due to protein. PEF = Proportion of total energy due to fat. PEC = Proportion of total energy due to protein. UEDP = Utilizable energy due to protein.
Table 1 still contains other parameters calculated from the proximate values. It shows the various energy values as contributed by protein, fat and carbohydrate. The daily energy requirement for an adult is between 2500-3000 kCal (10455-12548 kJ) depending on his physiological state while that of infants is 740 kCal (3094.68 kJ) [19]. This implies that while an adult man would require between 649-735 g (taking minimum energy of 1610 kJ/100 g) of his energy requirement, infants would require 192 g (taking the minimum energy for the calculation, excepting energy due to egg shells). On the whole these meant samples with higher energy value would require lower quantity of sample to satisfy the energy needs of man and infants. The energy values observed here were better than the value from the muscle and skin of turkey: an adult man would require between 786-944 g (muscle) and 761-913 (skin) to meet his minimum requirement, infants would require 233 g (muscle) and 225 g (skin) [17]. The utilizable energy due to protein (UEDP %) for the samples (assuming 60 % utilization) ranged from 0.65-51.6 %. The UEDP % in skin (0.65 %) is much lower than the recommended safe level of 8 % for an adult man who requires about 55 g protein per day with 60 % utilization. The UEDP % in muscle of turkey was 56.4 % and 40.0 % in the skin [17] whereas the values were 12.128.8 % (female and male exoskeleton), 12.5-23.8 % (female and male flesh) and 13.8-17.9 % (female and male whole body) of West African fresh water crab (Sudananautes africanus africanus) [20]. Other present UEDP % values from the samples ranged as 10.7-51.6 showing the greater
part of the samples have protein concentration in terms of energy that would be more than enough to prevent energy malnutrition in children and adult fed solely on the samples as a main source of protein (except the skin). The PEF % values were generally low in the samples (0.26-9.75 %) and far below the recommended level of 30 % [21] and 35 % [22] for total fat intake, this is useful for people wishing to adopt the guidelines for a healthy diet. Table 2 shows the mineral compositions of the samples. Copper and Cr were not detected in all the samples whereas Mn was not detected in eyes, muscle, heart and brain whereas phosphorus was not detected in the skin and gizzard. In the minerals the highest CV % was in Mn (126 %) and lowest in K (45.9 %). Minus Cu, Cr and Mn, all other minerals in the samples were significantly different at their various levels. Highest contributions of the minerals as food were (mg/100 g): Na(muscle, 44.8), K (muscle, 53.9), Ca (egg shell, 41.5), Mg (egg shell, 59.5), Zn (liver, 22.6), Fe (heart, 61.3), Mn (liver, 1.81) and P (eyes, 116). The highest Ca/P was 8.66 in egg shell; most favourable Na/K was 0.522 in eyes; highest [K/(Ca+Mg)] was 6.01 in liver and highest Ca/Mg was 0.925 in muscle. Na/K, Ca/Mg and [K/(Ca + Mg)] ratios were not significantly different in all the samples, however, Ca/P was significantly different. The CV % levels in the ratio parameters were 18.9-141 % whereas the range was 45.9-126 % in the other minerals. Among the major minerals, the muscle had the highest levels of Na (44.8 mg/100 g) and K (53.9 mg/100 g), egg shell had the highest levels of Ca (41.5 mg/100 g) and Mg
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Cu and Cr are needed in the diet, the present samples would need to be supplemented in those minerals when they serve as the only food sources. Iron was high in all the samples except skin (2.20 mg/100 g) and egg shell (0.960 mg/100 g). About 1-10 % of Fe from plant sources is normally absorbed by the body [24] although this value can be improved upon when plants are consumed with meat. For example, the addition of meat to legume or cereal diet can double the amount of Fe absorbed and so contribute significantly to the prevention of anaemia, which is so widespread in developing countries like Nigeria [24].
(59.5 mg/100 g), phosphorus was highest in the eyes (116 mg/100 g). In the minor minerals, liver was highest in Zn (22.6 mg/100 g), heart was highest in Fe (61.3 mg/100 g) and Mn was highest (1.81 mg/100 g) in the liver. Manganese has always been found low in the foods consumed in Nigeria. For examples, it was 1.9±0.04 mg/kg (meatpie), 1.0± 0.00 mg/kg (doughnut), 29±0.01 mg/kg (moin-moin) and cake (2.8±0.01 mg/kg) [23]. It is well known that minerals are necessary for life. Copper and Cr were not detected in any of the samples. Copper and Fe are present in the enzyme cytochrome oxidase involved in energy metabolism. Since
TABLE II MINERALS AND CALCULATED MINERAL RATIOS
Param eters Na K Ca Mg Zn Fe Mn Cu Cr P Ca/P Na/K Ca/Mg K/(Ca +Mg)*
Eyes
Muscl e
Skin
Heart
Gizzar d
Brain
Liver
Egg Shell
Mean
SD
CV%
X2
TV
Remar k
18.1 34.7 4.17 29.2 16.7 17.9 ND ND ND 116 0.036 0.522 0.143
44.8 53.9 36.9 39.9 7.45 42.0 ND ND ND 32.7 1.13 0.831 0.925
0.730 1.17 0.810 1.47 1.10 2.20 0.010 ND ND ND 0.624 0.551
34.6 40.6 25.2 32.6 12.1 61.3 ND ND ND 4.94 5.20 0.852 0.788
24.9 29.5 13.8 20.5 10.8 38.2 0.890 ND ND ND 0.844 0.673
18.4 33.9 11.6 31.6 13.2 38.1 ND ND ND 51.7 0.224 0.543 0.367
28.9 41.2 1.90 11.8 22.6 49.7 1.81 ND ND 26.7 0.071 0.701 0.161
40.7 52.5 41.5 59.5 4.89 0.960 0.010 ND ND 4.79 8.66 0.775 0.697
26.4 35.9 17.0 28.3 11.1 31.3 0.680 ND ND 39.5 2.55 0.709 0.538
14.2 16.5 15.9 17.7 6.77 22.0 0.86 41.5 3.58 0.134 0.289
53.8 45.9 93.4 62.5 61.0 70.3 126 105 141 18.9 53.7
53.5 53.0 104 77.4 28.9 109 3.27 218 25.2 0.177 1.08
14.07 14.07 14.07 14.07 14.07 14.07 14.07 14.07 14.07 14.07 14.07
S S S S S S NS S S NS NS
2.08
1.40
1.03
1.39
1.72
1.57
6.01
1.04
2.03
1.64
81.0
9.33
14.07
NS
α 0.05 df n-1, S = Significant, NS = Not significant, TV = Table value, X2 = Chi square. * = Milliequivalent ratio.
Zinc is present in all the samples at high levels. Zinc is present in all tissues of the body and is a component of more than 50 enzymes [24]. The minimum Zn allowance (about 15-20 mg) per day would be met by 100 g of eyes (16.7 mg/100 g) and liver (22.6 mg/100 g). The low concentration of Mn was in agreement to what obtains in meat [25, 26]. Manganese functions as an essential constituent for bone structure, for reproduction and for normal functioning of the nervous system; it is also part of the enzyme system [26]. Calcium was high in muscle, heart, gizzard, brain and egg shell. Calcium is an important constituent of body fluids. It is a coordinator among inorganic elements particularly K, Mg or Na where Ca is capable of assuming a corrective role when such metals are in excessive amount in the body [26]. Calcium, P and vitamin D combine together to avoid rickets in children and osteomalacia (the adult rickets) as well as osteoporosis (bone thinning) among older people [27]. A dietary regime of adequate dietary Ca over the years should be a deterrent to this condition. Phosphorus was high in the eye, muscle, brain and liver. Phosphorus is always found with Ca in the body, both contributing to the supportive structures of the body. It is present in cells and in the blood as soluble phosphate ion, as well as lipids, proteins, carbohydrates and energy transfer enzymes [28]. Phosphorus is an essential component in nucleic acids and the nucleoproteins responsible for cell division, reproduction and transmission of hereditary traits [28]. The samples are good sources of K (except skin), Mg (except skin) and Na
(except skin). Magnesium is an activator of many enzyme systems and maintains the electrical potential in nerves [28]. Potassium is primarily an intercellular cation, in large part this cation is bound to protein and with Na influences osmotic pressure and contributes to normal pH equilibrium [27]. In literature mineral results of some poultry egg shells, the followings were observed: Na in turkey (41.6 mg/100 g) was close to 40.7 mg/100 g in guinea-fowl, K in turkey (51.7 mg/100 g) was close to 52.5 mg/100 g in guinea-fowl, Ca in duck (42.3 mg/100 g) was close to 41.5 mg/100 g in guineafowl, Mg in francolin (60.0 mg/100 g) was close to 59.5 mg/100 g in guinea-fowl, Fe in francolin, duck and turkey (8.03-10.2 mg/100 g) were all much higher than in guineafowl (0.96 mg/100 g), Zn in duck (4.65 mg/100 g) was close to 4.89 mg/100 g in guinea-fowl and P in francolin, duck and turkey (117-151 mg/100 g) in guinea-fowl [12]. Table 2 further depicts the various mineral ratios that were calculated. The Ca/P was greater than 0.5 in muscle (1.13), heart (5.20) and egg shell (8.66) but not calculated for skin and gizzard (because phosphorus was not detected in the two) and low in the eyes (0.036), brain (0.224) and liver (0.071). The 0.5 value for Ca/P is the minimum ratio required for favourable Ca absorption in the intestine for bone formation [29]. High levels of Ca/P ratio would enhance strong bone development since absorption under this condition would be high. The Ca/P ratio is reported to have some effect on Ca in the blood of many animals [30]. Na/K ratios in the eyes and brain were lower than 0.60
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the samples could cause the reduction of Zn absorption in the small intestine and Fe poisoning particularly in children by some of the samples. The Zn MSI greater than 33 are above the recommended adult intake. The minimum toxic dose is 500 mg, or 33 times the RDA [5]. High doses of Zn can be harmful. Zinc supplements can decrease the amount of high density lipoprotein (HDL) circulating in the bloods, increasing risk of heart disease [32]. High doses of Zn can be harmful. Zinc supplements can decrease the amount of high density lipoprotein (HDL) circulating in the blood, increasing risk of heart disease [32]. Excess Zn interacts with other minerals, such as Cu and Fe, decreasing their absorption. In animals, Zn supplements decrease the absorption of Fe so much that anaemia is produced [33]. When patients are given 150 mg of Zn per day, Cu deficiency results. Intakes of Zn only 3.5 mg/day above the RDA decrease Cu absorption [29]. In animals, Cu deficiency causes scarring of the heart muscle tissue and low levels of Ca in the bone [32]. Excess Zn also decreases the functioning of the immune system. The Zn overload would come from 25 % of the present samples whereas in 25 samples of fish 96 % had Zn overload [34] and four samples of fast-foods 100 % had Zn overload, in Fe overload would come from 75 % of the present samples whereas in 25 samples of fish 16 % had Fe overload and four samples of fast-foods 100 % had Fe overload [23].
whereas other values were higher. The Na/K of 0.60 is the ratio that favours none enhancement of high blood pressure disease in man [29]. To bring this ratio low, food rich in potassium should be more consumed. The Ca/Mg values ranged between 0.143-0.925 whereas the recommended value is 1.0. Both Ca and Mg would need adjustment for good health. The milliequivalent ratios of [K/(Ca + Mg)] were all less than 2.2 except the liver with a value of 6.01. This means the majority of the samples would not promote hypomagnesaemia in man [31]. The mineral safety index (MSI) values of the samples are shown in Table 3. The standard MSI for the elements are Na (4.8), Mg (15), P(10), Ca (10), Fe (6.7) and Zn (33). For Na, the MSI values ranged from 0.01 (skin)- 0.43 (muscle), with all the differences between the standard and calculated MSI values being positive at 4.41-4.79, all less than 4.8. This meant that no samples might be overloading the body with sodium that can lead to secondary hypertension. For Ca, Mg and P (where calculated) all the calculated MSI were lower than standard MSI and hence within the USRDA [5]. For Fe and Zn, the odd samples out, respectively were eyes (-1.30), muscle (-12.1), (heart -20.7), gizzard (-10.4), brain (-10.3) and liver (-15.5); eyes (-3.70) and liver (-16.7). The implication of the above is that abnormally high levels of Fe and Zn were abnormally present in some samples. Some of
TABLE III MINERAL SAFETY INDEX OF NA, MG, P, CA, FE, AND ZN FOR THE VARIOUS VARIETY ORGANS OF GUINEA FOWL Na
K
Ca
Mg
Zn
Fe
Mn
Cu
Cr
P
CV
TV
D
-
CV
TV
D
CV
TV
D
CV
TV
D
CV
TV
Eyes
0.17
4.8
4.63
-
0.03
10
9.97
1.10
15
13.9
36.7
33
3.70
8.00
6.70
Muscle
0.43
4.8
4.37
-
0.31
10
9.69
1.50
15
13.5
16.4
33
16.6
18.8
6.70
Skin
0.01
4.8
4.79
-
0.01
10
9.99
0.04
15
14.96
2.42
33
30.6
0.98
6.70
Heart
0.33
4.8
4.47
-
0.21
10
9.79
1.22
15
13.8
26.6
33
6.38
27.4
6.70
Gizzard
0.24
4.8
4.56
-
0.12
10
9.89
0.77
15
14.23
23.8
33
9.20
17.1
6.70
Brain
0.18
4.8
4.62
-
0.10
10
9.90
1.19
15
13.8
29.0
33
4.00
17.0
6.70
Liver
0.28
4.8
4.52
-
0.02
10
9.98
0.44
15
14.6
49.7
33
16.7
22.2
6.70
0.39
4.8
4.41
-
0.35
10
9.65
2.20
15
12.8
10.80
33
22.2
0.96
6.70
D
CV
TV
D
Samples 1.30 12.1 5.72 20.7 10.4 10.3 15.5 5.74
-
-
-
0.97
10
9.03
-
-
-
0.27
10
9.73
-
-
-
-
10
-
-
-
-
0.04
10
9.96
-
-
-
-
10
-
-
-
-
0.43
10
9.57
-
-
-
2.23
10
7.8
-
-
-
0.04
10
9.96
Egg Shell CV = Calculated Value. TV = Table value. D = Difference. No MSI Standard for K, Mn, Cu and Cr.
IV.
CONCLUSIONS
In summary, this study indicates that the proximate and mineral profiles of heart, skin, muscle, brain, liver, eyes, gizzard and egg shells of guinea-fowl have varied compositions. In the results, UEDP % was poor in skin and egg shells, all samples were good in PEF % (< 30-35 %); PEC % was very high in eyes, skin and egg shells. Eyes, brain and liver were all poor in Ca/P but all the three were good in Na/K; all the samples were good in [K/(Ca + Mg)] (< 2.2) except liver (6.01); all samples were less than 1.0 in
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