Livestock Research for Rural Development 27 (9) 2015 Guide for preparation of papers LRRD Newsletter

Citation of this paper

Moringa oleifera leaf meal and molasses as additives in grain sorghum based diets; effects on egg quality and consumer preferences

J T Kaijage, S K Mutayoba1 and A M Katule1

Department of Animal Production and Marketing Infrastructures, Ministry of Livestock and Fisheries Development,
P.O. Box 9152,Dar-es-salaam, Tanzania
kaijage2000@yahoo.com
1 Department of Animal Science and Production, Sokoine University of Agriculture,
P.O. Box Morogoro, Tanzania.

Abstract

The comparative influence of Moringa oleifera leaf meal (MOLM) and final sugar cane molasses (SCM) in grain sorghum variety (GSV) based diets on egg quality characteristics and consumers’ preferences for commercial hybrid layer chickens was studied in 2x3 factorial designs. The study used two grain sorghum varieties (GSV): high tannin sorghum (HTS) and low tannin sorghum (LTS); three supplementary strategies (SPS) of non-supplemented and 10% DM- molasses and 10% DM-MOLM supplemented GSV to make six dietary treatments.

Roche yolk color score (RYS) value was higher in HTS compared to LTS. The consumers’ egg aroma score index (ASI) and egg taste score index (TASI) increased in HTS. The supplementation of MOLM increased RYS and YSI. However, both supplementation of sugar cane molasses and MOLM moderately decreased ASI and GAS. It can be concluded that HTS produced moderately acceptable eggs in terms of aroma, flavor and yolk color but enhanced egg yolk pigmentation and egg flavor and aroma whereas use of LTS could produce moderately acceptable eggs in terms of yolk color, aroma and flavor. Thus, its use could require supplementation with synthetic pigments, flavor and aromatic compounds. The supplementation MOLM in GSV diets could moderately improve egg yolk colour and minimize use of synthetic pigments whereas SCM could produce poor quality egg products and its use could require supplementation with synthetic pigments. Thus, utilization of 10% of MOLM as an additive to HTS and LTS for egg quality is suggested. The utilization of SCM as additive to HTS and LTS diets is not recommended due to negative effects on egg quality.

Key words: pigmentation, supplementation, tannin


Introduction

Sorghum is well adapted to marginal environment, rank fifth in global cereal hectares and is the most important grain cereal in the semi-arid tropical regions of Asia and Africa. The chemical composition of grain sorghum is comparable to maize except for being deficient in lysine, methionine and threonine (Sikka and Johari 1979; Rostagno et al 2000). Thus, grain sorghum has been used as an alternative to maize in poultry diets due to its high energy content. However, the utilization of grain sorghum in poultry has been limited due to the presence of tannins (Nelson et al 1975). Tannins in plants and fruits generally act as antioxidant and anti-pathogenic agents (Amarowicz et al 2000; Gorinstein et al 2001). However, high tannin concentration in poultry feeds may reduce nutritive value (Cherian et al 2002; Du et al 2002; Imik 2006). High levels of dietary tannins up to 2% may decrease egg quality characteristics (Potter et al 1967; Fry et al 1972; Faquinello et al 2014).

Several attempts has been made to curb the effects of tannins on egg quality by using synthetic amino acids, oil, pigments and minerals (Saldanha et al 2009; Bolukbasi et al 2010; Gül et al 2012). However, these nutritional regimes have been partial and expensive. Moringa oleifera leaf meal(MOLM) and molasses are readily available feed ingredients in the tropics with a great potential and good source of energy, minerals, vitamins and amino acids (Mathew et al 2001; Curtin 1902). The scanty of information on the utilization of MOLM and molasses to high tannin grain sorghum (HTS) based diets for layers impelled this study with the view of evaluating the effects of MOLM and molasses on grain sorghum based commercial layers diets on egg quality characteristics and consumer egg preferences. It was hypothesized that supplementation of molasses and MOLM would improve the adverse effects of tannin in sorghum on egg quality characteristics and consumer egg quality preferences through either being with essential nutrients. Therefore, the objective of this experiment was to determine on egg quality characteristics and consumer egg preferences resulting from the use of HTS and LTS as a sole use of energy into diets of hybrid egg strain layer during initial production period and whether supplementation of molasses and MOLM could ameliorate the adverse effects of tannins.


Materials and methods

Feed ingredients and experimental diets

The study was conducted at poultry unit of the Sokoine University of Agriculture (SUA) in the Department of Animal Science and Production (DASP), Eastern part of Tanzania. Moringa oleifera leaves were harvested within SUA compound, air dried under a shed to maintain their greenish colour, ground with hammer mill to produce MOLM. Grain sorghum varieties (GSV) were collected from the local markets, ground with hammer mill, passed through 2mm sieve to produce grain sorghum meal.

Molasses was obtained from Mtibwa sugar processing company. The methods of Association of Official Analytical Chemists (AOAC, 1990) were used to determine proximate composition, minerals and ash of the feed ingredients and experimental diets. Metabolizable Energy (ME/ kcal/kg) content of feed ingredients and experimental diets were estimated by prediction equations expressed by NRC (1994). MOLM, ME/Kgcal/kg was estimated by prediction equation established by Carpenter and Clegg (1956). Condensed tannins in GSV and MOLM were determined using butanol/HCL method as expressed by Nitao et al (2001). All MEn values were converted into MJ/KgDM. All diets were formulated to meet or exceed the nutrient requirements recommended by NRC (1994) (Table 1) for layer chickens. The inclusions of GSV in experimental diets were fixed to 55%DM.

Experiment design and dietary treatments

The six dietary treatments were arranged in 2x 3 factorial design of two GSV for (HTS) and (LTS) and three supplementary strategies (SPS) for non supplemented (0%) and 10%DM-molasses and 10%DM-MOLM for supplemented GSV, making six diets designated as CTL1, SCM1 and MOL1 and CTL2, SCM2 and MOL2 in HTS and LTS respectively. The name and description of experimental diets (D1-D6) are shown in Table 1.  

Experimental procedure

Two hundred and seventy (270) commercial bovan brown hybrid layer chickens at 20th week of age were randomly allocated to dietary treatment. Each dietary treatment had 45 birds subdivided into three replicates of 15 birds each. The birds were housed deep litter pens. The experimental diets were provided from 20th to 30th week of age. The experimental diets and clean drinking water were supplied to the birds without restriction throughout the study period. Light was supplied by electric bulb and sun at night and day time respectively. Vaccination and other routine poultry management practices were carried out. Four eggs from each replicate group, 12 eggs per treatment, were randomly sampled every three weeks for nine weeks for quality evaluation of physical and internal characteristic parameters. The egg shape index was calculated and expressed as a ratio of egg length to width. The egg length was measured in centimeter (cm) along the longitudinal axis and width measured along the equatorial axis using a venire caliper. The eggshell thickness was measured using micro-meter. Egg component proportions were weighed and proportions of their weights calculated. The eggs were carefully broken, opened by hand; yolk separated, dried using blotting papers and weighed using sensitive electronic balance. Eggshell weight was taken after oven drying the eggshells at 700 C for 24 hr. The albumen weights were determined by the difference between the whole egg weight and that of the yolk added to the shell weight. Egg component proportions were determined based on egg weight. Egg yolk colour scores were determined using a 15 grade Roche fans (Hoffman Roche Switzerland). Egg albumen and yolk solids were determined according to the AOAC (1990) procedure. Egg yolk cholesterol concentration was determined by chod-pap method and expressed as mg/dl.

At the end of the feeding experiment, sixty (60) untrained panelists, thirty women and thirty men, were randomly selected for egg preference evaluation. Eggs were randomly selected from each treatment replicate and coded with random numbers. Each panelist was allowed to randomly select one coded egg from each dietary treatment.All sampled eggs were boiled for five minutes and served to panelist while warm. A glass of water was provided to each panelist to rinse the mouth after testing each sample. Five score Hedonic sensory test was used in egg scoring. The five scoring points were 1,2,3,4 and 5 with scoring indices of 1-20, 21-40, 41-60, 61-80 and 81-100% for dislike very much, dislike moderately, neither like or dislike, like moderately and like very much respectively. Panelists indicated the degree of likeliness for each sampled egg by choosing appropriate category which suited their attitude towards eggs. The mean score of studied parameters in each replicated group was calculated by summation of score dividing to the number of panelists. Then the mean score index was calculated by score dividing to the highest score rank x 100.

Statistical analysis

All data on physical and internal egg quality characteristic and egg quality consumers’ score indices were analyzed in accordance with the 2x3 factorial designs of two GSV in combination with three SPS using General Linear Model procedure of SAS software version 9.1 for windows (2007). Values were considered significant at (P ≤ 0.05). The Least Square Difference was used to compare means of each variable. The analytical model for studied haematological parameters and serum biochemical indices was as follows: Yijk = μ + Vi + Sj+ (VS)ij+ eijk

Where:

Yijk = Observation of kth bird assigned to ith GSV subjected to jth SPS

μ = overall mean to all observations; I = effect of GSV based diet (HTS or LTS)

Sj = the effect of SPS based diet (CTL, SCM or MOL)

(VS)ik= the interaction between GSV and SPS

eijk = random error


Results

Effect of type of GSV

The overall means of physical and internal egg quality characteristics for GSV are shown in (Table 2). The egg shape index (ESI), egg shell thickness (EST), percent egg shell (PES), percent egg yolk (PEY), percent egg albumen (PEA), percent yolk solids (PYS), percent albumen solids (PAS), Roche yolk colour score (RYS) and egg cholesterol concentration (ECC) values were not influenced by type of GSV. However, the EST, PES and PEY values were moderately lower in HTS and higher in LTS dietary groups though not significant. The Roche yolk colour score (RYC) was higher in HTS and lower LTS dietary group.

The egg quality consumer’ score index for GSV are shown in (Table 5). The egg yolk colour scoring index (YSI), general acceptability egg scoring index (GASI) and total egg scoring index (TSI) were not influenced by type of GSV. But, the taste score index (TASI) and aroma score index (ASI) was higher in HTS and lower LTS dietary group.

Effect of supplementation

The overall means of physical and internal quality egg quality characteristics for SPS are shown in (Table 3). The ESI, EST, PES, PEY, PEA, PYS, PAS and ECC values were not influenced by type SPS. The supplementation of SCM and MOL to GSV diets did not affect EST, PES and PEY values. The supplementation of SCM did not change whereas supplementation of MOL increased the RYC values. The interaction (Table 4) between type GSV and type SPS was noted on RYC and RYC values. RYC and RYC values were moderately higher in MOL1 compared to MOL2 dietary group. The supplementation SCM in HTS and LTS based diet did not change but supplementation of MOL increased RYC values.

The overall means of consumer egg quality scoring indices for SPS are shown in Table 6. The results showed that, the three SPS had no influence on TASI and TSI values. The supplementation of SCM to GSV diets decreased ASI and GAS. Moreover, the supplementation of SCM did not change whereas supplement MOL increased YSI value.

Table 1. Composition of experimental diets

Ingredient

HT

LT

HT-Mo

LT-Mo

HT-ML

LT-ML

Moringa leaf meal

-

-

-

-

11. 3

11.3

Molasses

-

-

14.4

14.4

-

-

Sorghum meal (high tannin)

62.5

-

62.5

-

62.5

-

Sorghum meal ( low tannin)

-

62.3

-

62.3

-

62.3

Fish meal

10.0

10.0

10.0

10.0

10.0

10.0

Sunflower seed meal

18.0

18.0

18.0

18.0

18.0

18.0

Limestone

6.50

6.80

6.50

6.80

6.50

6.80

Premix

0.25

0.25

0.25

0.25

0.25

0.25

Bone meal

2.25

2.25

2.25

2.25

2.25

2.25

Salt

0.50

0.50

0.50

0.50

0.50

0.50

Chemical composition (%DM)

Dry matter

88.9

90.6

87.8

87.0

89.5

88.6

Crude protein

17.0

16.7

17.9

19.3

20.5

19.8

Crude fiber

9.60

9.27

7.41

6.50

10.6

8.03

Ether extract

7.52

9.51

5.62

6.34

9.08

9.85

NFE (Starch +sugar)

33.7

34.9

39.1

39.8

39.0

39.3

Lysine

0.885

0.868

1.091

1.101

3.102

3.12

Methionine &cystine

0.5087

0.499

0.655

0.6609

1.054

1.065

Tryptophan

0.186

0.183

0.213

0.215

0.263

0.265

Tannin

2.60

1.30

2.15

1.05

2.55

1.36

ME (MJ/kgDM)

9.42

8.77

8.606

9.23

9.27

9.105

HT--55%DM-High tannin grain sorghum based diet; LTS- 55%DM-Low tannin grain sorghum based diet; HT-Mo- 55%DM-High tannin grain sorghum+10%DM-molasses; LT-Mo- 55%DM-Low tannin grain+10%DM-molasses; HT-ML- 55%DM-High tannin grain sorghum+10%DM-Moringa leaf meal; LT-ML- 55%DM-Low tannin grain sorghum+10%DM-Moringa leaf meal .


Table 2. Physical and internal egg quality characteristics of commercial layer chickens fed grain sorghum variety based diets

Grain sorghum variety based diets

HTS

LTS

SEM

Prob

Egg shape index (%)

77.2

77.0

0.972

0.635

Egg shell thickness (µ)

193

210.7

20.62

0.0915

Percent egg shell (%)

12.3

12.6

0.306

0.0990

Percent egg yolk (%)

22.5

23.7

1.24

0.0699

Percent egg albumen (%)

51.5

51.1

0.859

0.374

Percent egg yolk solids (%)

49.9

52.0

4.038

0.290

Percent egg albumen solids (%)

12.8

13.3

0.549

0.115

Roche egg yolk colour score

3.98a

3.54b

0.382

0.0371

Egg cholesterol concentration ((mg/dl-1)

353

338

58.0

0.6006

ab Means in the same row with different superscripts are different (P = 0.05); SEM = Standard error of means; HTS-55%DM-high tannin grain sorghum based diet; LTS- 55%DM-low tannin grain sorghum based diet.


Table 3. Physical and internal egg quality characteristics of commercial layers fed MOLM and molasses supplemented in grain sorghum variety based diets (20-30 weeks of age)

Parameter

Supplementary diet

CTL

SCM

MOL

SEM

Prob

Egg shape index (%)

76.9

77.2

77.2

0.972

0.8609

Egg shell thickness (µ)

192

206

207

20.26

0.418

Percent egg shell (%)

12.3

12.4

12.6

0.306

0.273

Percent egg yolk (%)

22.7

23.0

23.7

1.24

0.345

Percent egg albumen (%)

51.4

51.3

51.2

0.549

0.947

Percent egg yolk solids (%)

51.1

51.8

49.9

4.038

0.723

Percent egg albumen solids (%)

12.9.

13.0

13.2

0.549

0.454

Roche egg yolk colour score

1.0b

1.0b

9.28a

0.382

0.0001

Egg cholesterol concentration ((mg/dl-1)

293

379

365

58.0

0.584

ab Means in the same row with different superscripts are different (P = 0.05); SEM = Standard error of means; CTL-55%DM-grain sorghum+’0’ supplementation; SCM-55%DM-grain sorghum plus 10%DM’ molasses supplementation; MOL-55%DM-grain sorghum plus10%DM-MOLM supplementation


Table 4. Interaction between grain sorghum variety and type of supplementary strategy on egg Roche colour score for commercial layer chickens (20-30weeks of age).

Parameter

TS

LTS

CTL1

SCM1

MOL1

CTL2

SCM2

MOL2

SEM

Prob

Roche egg colour score

1.0a

1.0a

9.28b

1.0a

1.0a

8.63b

0.382

0.0215

abc Means in the same row with different superscripts are different (P = 0.05); SED = Standard error of means; CTL1-55%DM- high tannin grain sorghum +’0’ supplementation;CTL2 -55%DM- low tannin grain sorghum+’0’ supplementation; SCM1-55%DM- high tannin grain sorghum plus 10%DM’ molasses supplementation; SCM2-55%DM- low tannin grain sorghum plus 10%DM’ molasses supplementation; MOL1-55%DM- high tannin grain sorghum plus10%DM-MOLM supplementation; MOL2-55%DM- low tannin grain sorghum plus10%DM-MOLM supplementation.


Table 5: Consumer egg quality scoring indices for commercial layer chickens fed two types of GSV based diets

Parameter (%)

Grain sorghum variety based diets

HTS

LTS

SEM

Prob

Egg taste score index

73.6a

67.3 b

5.34

0.0329

Egg aroma score index

64.2 a

59.6 b

3.96

0.030

Egg yolk colour score index

63.1

63.8

8.96

0.878

Egg general acceptability score index

65.11

62.00

5.39

0.249

Egg total consumer score index

50.8

48.9

2.42

0.128

ab Means in the same row with different superscripts are different (P = 0.05); SEM = Standard error of means; HTS-55%DM-high tannin grain sorghum based diet; LTS- 55%DM-low tannin grain sorghum based diet. Scoring index: 1-20%-dislike very much; 21-40%-dislike moderately; 41-60%- neither like nor dislike: 61-80- like moderately and 81-100%-like very much


Table 6: Consumer egg scoring indices for commercial layers chickens fed MOLM and molasses supplemented in grain sorghum variety based diets (20-30 weeks of age)

Parameter

Supplementary diet

   CTL

SCM

MOL

SED

Prob

Egg taste score index (%)

73.0

68.3

70.0

5.34

0.347

Egg aroma score index (%)

67.3a

58.3b

60.0b

3.96

0.0063

Egg yolk color score index (%)

53.7b

56.7b

80.0a

8.96

0.0009

Egg general acceptability score index (%)

67.3a

63.3b

60.0bc

5.39

0.1091

Egg total consumer score index (%)

51.2

48.3

50.0

2.42

0.175

ab Means in the same row with different superscripts are different (P = 0.05); SED = Standard error of difference; CTL-55%DM-grain sorghum+’0’ supplementation; SCM-55%DM-grain sorghum plus 10%DM’ molasses supplementation; MOL-55%DM-grain sorghum plus10%DM-MOLM supplementation. . Scoring index: 1-20%-dislike very much; 21-40%-dislike moderately; 41-60%- neither like nor dislike: 61-80- like moderately and 81-100%-like very much.


Discussion

In the present study PEA, PYS and PAS values did not differ significantly in HTS and LTS dietary groups. These results were in conflict with other previous studies (Ali and Mahmood 2003; Ebadi et al 2005; Imik 2009) that showed negative effect of tannins on albumen and yolk solids. These results probably imply that dietary tannin in the present study was not high enough to affect those parameters. These findings suggest that it is possible to utilize HTS with dietary tannin up to 2.6% of the diet DM as leucocynidin equivalent without detrimental effect on internal egg characteristics.

ESI, EST and PES values were comparable in HTS and LTS dietary groups in the present study. These findings are in agreement with previous research reports (Faquinello et al 2004; Imik et al 2006). However, they were in contrast with those of Ali and Mahmood (2003) that reported a decrease in egg shell thickness and egg shell strength in birds fed HTS based diets. Tannin intake is negatively correlated with egg shell thickness (Ebadi et al 2005). Tannins may reduce availability of minerals and change cation- anion balance in blood and availability of HCO3 and eventually reduce egg shell thickness (Sell et al 1983, 1984). Tannins may also affect bio-availability of calcium (Mehansho et al 1987; Chang et al 1993) and reduce egg shell thickness. These findings may suggest that dietary tannin in the present study was not high enough to negatively affect those parameters or a high level of dietary protein probably offsets the negative effects of tannins (Sell et al 1983). These findings suggest that there is a possibility of utilizing HTS based diet with dietary tannins up to 2.6% in DM as leucocynidin equivalent in layer chickens without getting detrimental effects on physical egg shell characteristics and egg shell quality if diets are supplemented with adequate calcium or have high protein content.

In the present study RYS values were higher in HTS and lower in LTS dietary groups indicating presence of more pigments in HTS than LTS. These results are in agreement with other previous research reports (Çabuk et al 2004). Polyphenolic compounds such as condensed tannins have been reported to increase deposition yellow yolk pigments and decrease malonaldehyde formation in the yolk. Also, anti-oxidants such as condensed tannins may cause excessive deposition of pigments in the egg yolk (Loetscher et al 2003; Chukwuka et al 2011) and that minimizes losses of oxycarotenoids which occurs due oxidation particularly during storage (Seemann, 2000). These findings imply that lower RYS values noted in LTS treatment groups probably were associated with losses of pigments due to oxidation whereas higher RYS values observed in HTS could be due to excessive deposition of pigments by tannins that offset losses of pigments during storage. However, these findings are in conflict with other research reports (Ali and Mahmood 2003; Faquinello et al 2004) that showed a decrease of pigments in egg yolk with increase of tannin intake. The conflicting results might be associated with differences in storage conditions and level of pigments in grain sorghum.

The effect of tannin on egg cholesterol content is variable and dose dependent. In the present study, egg cholesterol concentration values amongst HTS and LTS dietary group were similar. These findings suggest that the effect of tannins on egg cholesterol were not evident. These results disagree with other research reports (Stensvold et al 1992; Ali and Mahmood 2003; Oh et al 2013). The reasons for conflicting results in the present study may be associated with differences in dietary tannin content. These findings suggest that dietary tannins up to 2.6% of DM as leucocynidin equivalent were not high enough to reduce egg cholesterol concentration.

Acceptability of egg yolk color by consumers for eggs from HTS and LTS diets was moderate. These findings may be related to the pale egg yolk products noted in LTS and HTS dietary groups due to absence of pigments in GSV. Consumers perceive that eggs with pale yolks are not attractive and could be poor in nutritive value. Yolk colour is a very important parameter by which consumers judge the quality of eggs (Jacob et al 2000) and is an important egg quality attribute for egg marketing in different countries. These findings suggest that utilization of HTS and LTS as a main source of energy for layer chickens could produce undesirable egg products. The visual yolk color liked by consumers is the result of the deposition and coloring capacity of oxy-carotenoids, called xanthophylls, in the egg yolk (Coutts and Wilson 1990). Sources of xanthophylls can be natural or synthetic. Thus, the utilization of GSV as a main source of energy for layer chickens should be supplemented either by natural or synthetic pigments to improve egg acceptability by consumers.

Egg flavor acceptability by consumers for eggs from HTS and LTS diets was moderate. These findings suggest that the presence of phenolic compounds other than tannins may affect sensory characteristics and nutritional quality of grain sorghum and its subsequent products (Hahn et al 1984). These compounds alone or in combination with other compounds give rise to sensory characteristic that impart astringency, bitter or sour tastes (Maga and Lorenz 1973) which may affect overall acceptability of eggs. However, higher egg taste scoring index was noted in HTS whereas lower taste scoring index was observed in LTS diets, and may have been due to differences in tannin. The taste of bitterness and the tactile sensation of astringency are elicited primarily by flavanol polymers (proanthocyanidins or condensed tannins). Variations in proanthocyanidin composition, such as polymer size, extent of galloylation, and formation of derivatives, affect both bitterness and astringency. The social influence could be the reason for higher egg taste scoring index in HTS (Lesschaeve and Noble 2005). These findings suggest that utilization of GSV as a main source of energy could require supplementation with flavour rich compounds to increase acceptability of eggs.

Aroma acceptability by consumers for eggs  from HTS and LTS diets was indecisive.  These findings may be attributed to loss of desirable aromatic compounds in HTS and LTS during storage. However, higher egg aroma acceptability noted in HTS diets and lower egg aroma acceptability observed in LTS diets suggest the presence of higher aromatic compounds (ashy or smokey) in HTS due to tannin effects and lower aromatic compounds in LTS due to oxidation during storage. Tannins as natural antioxidants enable retention of aromatic compounds from the action of oxidasic enzymes, such as laccase and free radicals that are formed from the oxidation of polyphenolic molecules. These findings suggest utilization of HTS and LTS could require supplementation of aromatic compounds to improve aroma acceptability in eggs.

The supplementation of SCM and MOLM to GSV based diet slightly increased ESI, EST, PEA and PEY values indicating inadequacy of nutrients particularly minerals in GSV. Thus, supplementation with molasses and MOLM compensated deficient nutrients in GSV to optimize egg shape index, egg shell thickness, egg albumen and yolk weight values. These findings suggest use of SCM and MOLM as additives to GSV could slightly compensate deficient minerals particularly calcium and minimize cost of using synthetic minerals. These results agree with other previous studies (Olugbemi et al 2010; Ebenebe et al 2013). However, the supplementation of MOLM and SCM to GSV had no influence on PAS and PYS values suggesting adequacy of nutrients particularly proteins and amino acids responsible for development of albumen and egg yolk solids in GSV. These findings suggest utilization of SCM and additives can improve physical characteristics of eggs.

Supplementation with SCM to the GSV based diet did not change RYS whereas supplementation with MOLM increased RYS values. These results may be attributed to absence of xanthophylls and carotenoids in SCM (Kaijage et al 2014) and presence of xanthophylls which are characterized by the presence of hydroxyl groups and carotenoid pigments in MOLM (Fuglie 1999). Colour is the most important quality attribute of egg yolk. Consumer’s preferences for yellow yolk colour have been linked with high nutritional value and attractiveness of eggs (Wells 1968). Therefore, these results suggest that utilization of SCM as additive to GSV based diets for poultry cannot improve desirability of egg products in the egg marketing industry and its utilization will necessitate use of synthetic pigments to produce colored yolk products to improve acceptability.  These findings suggest that utilization of MOLM as additive to GSV can improve the egg yolk colour desirable to consumers; and that its use in the poultry industry could promote the use of natural pigments in situations where synthetic pigments are expensive or their  availability is restricted. These results concur to other previous research reports (Kaijage 2003; Olugbemi et al 2010; Abou-Elezz 2011).

However, the interaction between GSV and SPS on RYS observed in the present study suggests differences between HTS and LTS in he amounts of pigments. The HTS had moderately higher whereas LTS had lower RYS suggesting higher concentrations of pigments in HTS and lower concentrations in LTS. These findings support other studies that tannins can enhance deposition or prevent oxidation of pigments (Faquinello et al 2004). Therefore, HTS could enhance absorption of natural and synthetic pigments and minimize loses of pigments particularly during storage, and eventually produce desirable and acceptable egg yolk colour.

In the present study, supplementation of SCM and MOLM to GSV had no influence on ECC values. These findings disagree with other previous research studies (Ghasi et al 2000; Olugbemi et al 2010; Lala et al 2012) that showed SCM and MOLM to have hypocholesterolemic properties. The hypocholesterolemic nature of MOLM may be partly explained by high fiber content in MOLM that block intestinal cholesterol absorption (Lansky et al 1993) or presence of bioactive phytochemicals, the phytosterols such as β-sito-sterols, campe-sterols, stigma-sterols and avenasterol in MOLM that lower plasma concentration of low density lipoproteins (LDL), cholesterol (Ghasi et al 2000; Mbikay 2012) and ultimately lower cholesterol concentration in eggs. Sterols are also reported to inhibit cholesterol production in the liver. Further, the hypocholesterolemic mechanisms of SCM are associated with a series of n-alkenes (C23-C33) and ethyl and methyl esters of fatty acids (mainly oleate and palmamitate) of phytosterols (stigma-sterol, campestrols, and β-sito-sterols), free fatty acids and triglycerides and keto-steroid derivatives contained in molasses which could inhibit intestinal cholesterol absorption and thereby lower plasma total LDL cholesterol levels (Ghasi et al 2000) and ultimately could lower cholesterol in eggs. The reasons for conflicting results in the present study with other previous studies are not clear but could be due to differences in inclusion of SCM and MOLM.  These findings suggest utilization of SCM and MOLM as additives to GSV based diets has no influence on egg cholesterol concentration.

The present study showed that flavor of eggs from three types of SPS diets was moderately accepted by consumers. The sugary flavor from compounds such as acetic acid, valeric acid, benzoic acids and syringic acids reported in sugar cane molasses (Takesh et al 1967) and pungent flavor caused by phytochemical-2-pentatione reported in moringa leaves were not evident in eggs. These findings suggest that supplementation of SCM and MOLM as additives to GSV based diet did not improve consumer acceptability for egg flavor.

Acceptability of aroma in eggs from the three types of SPS diets was uncertain. These findings suggest that supplementation of SCM and SCM had no influence on egg aroma. However, the decrease in aroma acceptability in SCM and MOL compared to CTL was associated with slightly strong fruity aroma reported in molasses and moringa leaves (Pinnott et al 2006). Therefore, the use of 10% SCM and MOLM as additives to GSV based diets may negatively affect acceptability of egg aroma.

The supplementation of SCM to GSV based diet did not change customer preference whereas supplementation with MOLM increased preference for egg yolk color. These findings were attributed to pale egg yolk noted in SCM diets due to lack of pigments and yellow egg yolk observed in MOLM due to presence of pigments. Consumers prefer pigmented egg yolk such as yellow or deep yellow (Faquinello et al 2004). The pigmented egg yolk is associated with high nutritive value. Therefore use of molasses as additive to GSV based diet could produce undesirable egg products. Therefore, its utilization may require supplementation of synthetic pigments for production of coloured yolk egg products preferred by consumers. However, use of moringa leaf meal as additive to GSV improves egg yolk colour preference by consumers and could minimize use of synthetic pigments. These results agree with previous research findings (Kaijage 2003; Olugbemi 2010).


Conclusions


Acknowledgment

We are grateful to the Tanzanian Government through Ministry of Livestock and Fisheries Development for funding the research project.


References

Abou-Elezz F M K, Sarmiento-Franco L, Santos-Ricalde R and Solorio-Sanchez F  2011 Nutritional effects of dietary inclusion of Leucaena leucocephala and Moringa oleifera leaf meal on Rhode Island Red hens’ performance. Cuba Journal of Agriculture Science, 45: 163–169.

Al-Mamary M,  Molham A, Abduwali A and  Obeidi A 2001  In vivo effects of dietary sorghum tannins on rabbit digestive enzymes and mineral absorption. Nutrition Research, 21: 1393-1401.

Amarowicz R, Naczk M and Shahidi F  2000 Antioxidant activity of crude tannins of canola and rapeseed hulls. J Am Oil Chem Soc. 77:957–961.

Association of Official Analytical Chemists (AOAC) 1990 Official Methods of Analysis. 15th Edn, Washington, DC.

Bolukbasi C S, Erhan M K and Urusan H 2010 The effect of supplementation of Bergamot oil (Citrus bergania) on egg production, egg quality quantity, fatty acid composition of egg yolk in laying hens. Journal of poultry science, 47:163-169.

Çabuk M, Serdar Eratak and Hatice Basmacioğlu Malayoğlu 2014 Effects of Dietary Inclusion of Lentil By product on Performance and Oxidative Stability of Eggs in Laying Quail. The Scientific World Journal Volume 2014 (2014), Article ID 742987, 5 pages http://dx.doi.org/10.1155/2014/742987.

Carpenter K J and Clegg 1956 The Metabolizable energy of poultry feedstuff in relation to their chemical composition. Journal of Science, Food & Agriculture 7:45.

Chang M J and Fuller H l 1993 Dietary tannin from cowpeas and tea transiently alter apparent calcium absorption but not absorption of protein in rats. Journal of Nutrition 1993; 124:283-288.

Cherian G R K, Selvaraj M P, Goeger and Stitt P A 2002 . Muscle fatty acid composition and thiobarbituric acid-reactive substances of broilers fed different cultivars of sorghum. Poultry Science. 81:1415-1420.

Chukwuka O K, Okoli I C  Okeudo N J,  Udedibie A B I, Ogbuewu I P,  Aladi N O and Omede A A 2011  Egg Quality Defects in Poultry Management and Food Safety. Asian Journal of Agricultural Research, 5: 1-16.

Coutts J A and Wilson G C 1990 Egg Quality Handbook. Queensland Department of Primary Industries, Australia.

Curtin L V 1902 Molasses- General Considerations. Article, 500 Willowmere Lane Ambler, Pennsylvania, USA http://rcrec-ona.ifas.ufl.edu/pdf/publications/molasses-general-considerations.pdf.

Du M, Cherian G, Stitt P A and Ahn D U  2002  Effect of dietary sorghum cultivars on the storage stability of broiler breast and thigh meat. Poultry Science, 81:1385-1391.

Ebenebe C I, Anigbogu C C, Anizoba M A and Ufele A N 2003  Effect of various levels of Moringa Leaf Meal on the Egg Quality of Isa Brown Breed of Layers. Advances in Life Science and Technology, 14: ISSN 2224-7181. http://iiste.org/Journals/index.php/ALST/article/viewFile/8612/8809.

Fry J L, Herrick G M, Prine G M and Harms R H  1972 Effect of bird-resistant sorghums and tannic acid on yolk mottling. Poultry Science, 51:1540–1543.

Fuglie  L J  1999 . The Miracle Tree: Moringa oleifera Natural Nutrition for the Tropics. Church World Service, Dakar. 68 pp.; revised in 2001 and published as The Miracle Tree: The Multiple Attributes of Moringa, 172 pp.

Ghasi S, Nwobodo E and Ofili J O 2000 Hypocholesterolemic effects of crude extract of leaf Moringa oleifera Lam in high fat diet fed wistar rats. Journal of Ethno-pharmacology 69(1):21-25.

Gorinstein S, Martin Belloso O, Park Y, Harvenkit R, Lojek A, Milan I, Gaspi A, Libman I and Trakhtenberg S 2001 . Comparison of some biochemical characteristics of different fruits. Food chemistry, 74 (3): 309-315.

Gül M, Yörük M A, Aksu T and Kaynar Ö 2012  The effect of different levels of canola oil on performance, egg shell quality and fatty acid composition of laying hens. International Journal of Poultry Science. 11(12):769-776.

İmik H,  Hayirli  A, Turgut1 L,  Laçin E, Çelebi S,  Koç F and Yıldız  L 2006  Effects of Additives on Laying Performance, Metabolic Profile, and Egg Quality of Hens Fed a High Level of Sorghum (Sorghum vulgare) during the Peak Laying Period Asian-Aust. J. Animal Science, 19 (4): 573-581.

Jacob J P, Miles R D and Mather F B  2000 Egg Quality. University of Florida. http://edis.ifas.ufl.edu/pdffiles/PS/PS02000.PDF

Kaijage J T 2003 Effect of substituting Sunflower Seed Meal with Moringa oleifera leaf meal on the performance of commercial egg strain chicken and egg quality. Unpublished Dissertation for Award of MSc Degree in Animal Science at Sokoine University of Agriculture, Morogoro, Tanzania.

Lala A O, Kinloye, Arigbede O A and Dele P A 2012 Effects of Moringa oleifera leaf meal on the quality, antioxidant and cholesterol content of eggs. Journal Home, 10 ( 2) http://www.ajol.info/index.php/joafss/article/view/98348.

Lanksy P S, Schleicher H, Philipson J D and Loew D 1993 Plants that lower cholesterol. First World Congress on Medicinal and Aromatic Plants for human welfare, Maastricht, Netherlands,Acta- Horticulture 332: 131-136.

Lesschaeve I and Noble A C 2005 Polyphenols: factors influencing their sensory properties and their effects on food and beverage preferences. The American Journal of clinical nutrition, volume 81 (1):3305-3355.

Loetscher Y, Kreuzer M and Messikommer R E 2013 Utility of nettle (Urtica dioica) in layer diets as a natural yellow colorant for egg yolk  

Matthew T, Matthew Z, Taji S A and Zachariah S 2001 A review of Viricidal Ayurvedic Herbs of India for Poultry Diseases. Journal of American Holistic Veterinary Medicine Association 20(1):17.

Mehansho H, Butler LG and Carlson DM 1987 Dietary tannins and salivary prolinerich proteins: interactions, induction and defence mechanisms. Animal Review of Nutrition 1987; 7:423-440.

Nelson T S, Stephenson E L, Burgos A, Floyd J and York O J 1975  Effect of tannin content and dry matter digestion on energy utilization and average amino acid availability of hybrid sorghum grains. Poultry Science 54:1620-1623.

Nitao J K, Birr B A, Nair M G, Herms D A. and Mattson W J 2001 Rapid Quantification of Proanthocyanidin (Condensed tannins) Journal of. Agriculture, Food Chemistry 49:2207-2214.

NRC 1994 Nutrient requirements of poultry. Ninth revised edition. National Academic Press. Washington D. C., USA. 155pp.

Oh S T, Zheng L, Shin Y K., An B K and Kang C W 2013  Effects of Dietary Persimmon Peal and its Ethanol Extract on the Production Performance and Liver Lipids in the late stage of Egg production in laying Hens. Asian-Australas. Journal Animal Science, 26(2): 260-265.

Olugbemi T S, Mutayoba S K and Lekule F P 2010Moringa oleifera leaf meal as a hypocholesterolemic agent in laying hen diets Livestock Research for Rural Development 22 (4).

Olugbemi T S, Mutayoba S K and Lekule F P 2010 Evaluation of Moringa oleifera leaf meal inclusion in cassava chip based diets fed to laying birds Livestock Research for Rural Development 22 (6) 2010.

Pinotti T, Carvalho P M B, Garcia K M G, Silva T R, Allen Norton Hagler and Leite S G F 2006 Media components and amino acid supplements influencing the production of fruity aroma by Geotrichum candidum Industrial microbiology short communication . Braz. J. Microbiology. vol.37 no.4 http://www.scielo.br/scielo.php?pid=S1517-83822006000400017&script=sci_arttext.

Potter D K, Fuller H L and Blackshear C D 1967Effect of tannic acid on egg production and egg yolk mottling. Poultry Science. 46:1508–1512.

Pourreza J S, Esmaeilkhanian A and Gharadaghi A 2005 Effect of Sorghum Tannin on Egg Quality and Quantity of Laying Hen. Article. Isfahan University Technology, Iran. httpe://www.researchgate.net/profile/Javad_Pourreza .

Rostagno H S, Silva D J e Costa P M 2000 Composição de alimentos e exigências nutricionais de aves e suínos. (Tabelas Brasileiras). Ed. Imprensa Universitária. Viçosa, MG., 139 p.

Saldanha E S P B, Garcia E A, Pizzolante C C, Faittarone A B G, Sechinato A da, Molino A B and Laganá C 2009 Effect of Organic mineral Supplementation on the Egg Quality of Semi-Heavy Layers in Their Second Cycle of Lay. Brazilian Journal of Poultry Science , 11 (.4): 215 – 222 http://www.scielo.br/pdf/rbca/v11n4/v11n4a5.pdf.

Seemann Maria 2000 Factors which influence pigmentation. Lohmann Information, Cuxhaven, Germany: pp 26.http://www.lohmann-information.com/content/l_i_24_article_4.pdf

Sikka K C and Johari R P 1979 Comparative nutritive value and amino acid content of different varieties of sorghum and effect of lysine fortification. J. Agric Food Chem. 27:962-965.

Stensvold I, Iverdal A, Solvouk and Foss O P 1992 Tea consumption relationship to cholesterol, blood pressure and coronary and total mortality. Preventive Medicine, 21: 546-553.

Takesh Hashizume, Tohru Yamagami and Yukiko Sasaki 1967 Constituents of cane molasses. Separation and identification of the phenol compounds. Agricultural Biological Chemistry, Vol. 31, No. 3: 324-324.

Wells R G 1968 The measurement of certain egg quality characteristics. A review in egg quality. In: Egg quality. A study of the hen’s egg. (Edited by Carter, T.C., Oliver, and Boyd, Edinburg. pp 207-250


Received 1 April 2015; Accepted 1 August 2015; Published 1 September 2015

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