Response of Growing Rabbits to Diets Containing Different Levels of Protein and Mustard Seeds (Sinapisalba Linn)

A total number of 54 male growing New Zealand rabbits were used to study the effect of two different levels of ration protein supplemented with Mustard seeds(Sinapis alba Linn). Rabbits were classified into six equal groups (G1-G6). The 1 and 4 groups received basal ration with 100 % and 90 % protein requirement and served as first and second control respectively. The 2 and the 3 groups received basal ration with 100 % protein requirement supplemented withSinapisalba Linn at the level of 0.5 and 1.0 %, respectively. The 5 and 6 groups received basal ration with 90 % protein requirement with Sinapisalba Linn at the level of 0.5 and 1.0 %, respectively. The low level of protein (90% of protein requirement containing diet) significantly increased (P<0.05) DM, OM, CP, CF and NFE digestibility and TDN value compared to 100% of protein requirement. The high level of supplementation (1% Mustard seeds) significantly (P<0.05) improved all nutrient digestibility coefficients and nutritive values. The 90% protein ration with 1 % mustard seeds (G6) showed the best digestion coefficients of DM, OM, CP, EE and NFE and TDN value. However, the 100% of protein requirement with 1 % mustard seeds containing diet (G3) showed the high value of DCP. Inclusion Mustard seeds at 1% in rabbit diets significantly (P<0.05) increased all nutrient digestibility and nutritive values compared to control diet. Inclusion Mustard seeds at 0.5% significantly (P<0.05) increased the DM and EE digestibility and total digestible nutrient compared to control diet. The interaction between the protein and mustard seeds levels significantly (P<0.05) increased the all nutrient digestibility coefficients (DM, OM, CP, CF, EE and NFE) and nutritive values (TDN and DCP). Inclusion Mustard seeds at 0.5% or 1% significantly (P<0.05) improved the final or weight, total body weight gain, average daily gain and feed conversion compared to control diet. On the other hand inclusion of Mustard seeds at 1% significantly (P<0.05) increased the total body weight gain and average daily gain by 24.3% while at 0.5% significantly (P<0.05) increased the total body weight gain and average daily gain by 14.5% compared to the control group. The 90% of protein with 1% mustard seeds recorded the best values of final weight, total body weight gain, average daily gain and feed conversion. The interaction between the protein and mustard seeds levels significantly (P<0.05) increased the final weight, weight gain, average daily gain and www.ccsenet.org/jas Journal of Agricultural Science Vol. 4, No. 1; 2012 Published by Canadian Center of Science and Education 191 feed conversion. Inclusion mustard seeds in rabbit diets clearly decreased the dressing percentages by increasing the level of mustard seeds in rabbit diets. Dietary 90% of protein requirements with 0.5% or 1% mustard seeds showed the higher value ofnet revenue, economical efficiency and relative economic efficiency, as well as the lower value of feed cost/ kg live body weight (LE).


Introduction
Recently, it has found that some medicinal plants had some properties as growth enhancement.Some medicinal plants can be used as natural additives, tonic and restoratives in animal and poultry diets (Boulos, 1983), or to improve growth performance, immunity and the viability (El-Hindawyet al., 1996).Mustard oil is used as a flavoring in very low quantities (Koppelmanet al., 2007).Mustard green/leafy vegetables, when consumed regularly after steam cooking, would lower the risk of cardiovascular disease and cancer, advance nutrition research, and improve public health (Kahlonet al., 2008).Mustard oilhas been successfully applied inprophylactic of hyperacidity, gastric and duodenal ulcer (Gawronet al., 2005).Sinapisalba Linn (Commonly called yellow or white mustard) is an entomophilic species included in the Brassicaceae family, and their components have been reported to possess anticancer properties (Eskinet al., 2007).Sinapine is the effective component of Sinapisalbathat has a great potential in the field of antiageing drugs (Liu et al., 2006) and considered as an important natural antioxidant (Müller et al., 2001).Sinapisalba is a good candidate to use for immunotherapy purposes in future (Palomareset al., 2005).Bis-iodo phenol mustard has potential for use in future antibody-directed enzyme pro-drug therapy systems (Francis et al., 2002).
Low dietary protein requirements maycause imbalance in the body metabolism and growth performance.The hypothesis that sulfurcompounds has ability to repair the tissue defection protein of the cells.Sulfur mustard vesicants target thioredoxinreductase and that this may be an important mechanism mediating oxidative stress and tissue injury (Jan et al., 2010 andGray et al., 2010).Sulfur is indispensable for synthesis of certain compounds-mainly sulphatedmucopolysaccharides in the body (Georgievskiiet al., 1982).The requirements of sulfur containing amino acids by monogastric animals is 3-4 percent of the feed protein, and the requirement for sulfur is 0.6-0.8percent of the protein (Georgievskiiet al., 1982).The common albumin isolated from Sinapis alba seeds is composed of two disulfide-linked polypeptide chains of 39 and 88 amino acids as well as glutamine-rich large chain, proline-rich zein, a gliadin, and trypsin and alpha-amylase inhibitors isolated from the seeds of several monocotyledons, whose primary structures are reported by Menéndez-Arias et al. (1988).Mustard oil glycosides are derived from methionine, phenylalanine and tryptophan (Chavadejet al., 1994).
Tthe main objectives of this study was to evaluate the effect of Mustard seeds(Sinapisalba Linn) as feed additives in the diets of growing rabbits on feed utilization, growth performance, carcass characteristics and economic efficiency.

Materials and Methods
Fifty four male New Zealand White rabbits aged 5 weeks with an average body weight of 706 ± 4.64g were divided into six equal groups.The basal experimental diet was formulated and pelleted to cover the nutrient requirements of rabbits as a basal diet according to (NRC, 1977) as shown in (Table 1).The feeding period was extended for 70 days, and the experimental groups were classified as follow: Group 1 basal diet with 100 % protein requirement and served as control (G 1 ), Group 2 basal diet with 100 % protein requirement + 0.50% Mustard seeds (G 2 ), Group 3 basal diet with 100 % protein requirement + 1.00% Mustard seeds (G 3 ), Group 4 basal diet with 90 % protein requirement and served as control (G 4 ), Group 5 basal diet with 90 % protein requirement + 0.50% Mustard seeds (G 5 ) and Group 6 basal diet with 90 % protein requirement + 1.00% Mustard seeds (G 6 ).
Rabbits individually housed in galvanized wire cages (30 x 35 x 40 cm).Stainless steel nipples for drinking and feeders allowing recording individual feed intake for each rabbit were supplied for each cage.Feed and water were offered ad-libitum.Rabbits of all groups were kept under the same managerial conditions and were individually weighed, and feed consumption was individually recorded weekly during the experimental period.
At the end of the experimental period all rabbits in feeding trials were used in digestibility trials over period of 7 days to determine the nutrient digestibility coefficients and nutritive values of the tested diets.Feces were daily collected quantitatively.Feed intake of experimental rations and weight of feces were daily recorded.Representative samples were dried at 60C for 48 hrs, ground and stored for later chemical analysis.
At the end of the experimental period, six representative rabbits from each treatment were randomly chosen and fasted for 12 hours before slaughtering according to Blasco et al. (1993) to determine the carcass measurements.Edible offal's (Giblets) included heart, liver, testes and kidneys were removed and individually weighed.Full and empty weights of digestive tract were recorded.Weights of internal and external offal's were calculated as percentages of slaughter weight (SW).The 9, 10 and 11 th ribs were frozen in polyethylene bags for later chemical analysis.The ribs of samples were dried at 60 C for 24 hrs.The air-dried samples were analyzed for DM, EE and ash according to the A.O. A.C. (2000) methods, while CP percentage was determined by difference as recommended by O'Maryet al. (1979).Chemical analysis of experimental rations and feces were analyzed according to A.O.A.C (2000) methods.Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were also determined in the experimental rations according to Goering and Van Soest (1970).
Non fibrous carbohydrates (NFC), calculated according to Calsamigliaet al. (1995) using the following equation: NFC = 100 -{CP + EE + Ash + NDF}.Compositions of the experimental rations have been done according to the NRC (1977) requirements as shown in (Table 1).Diets were offered pelleted at 4 mm diameter.
Economical efficiency of experimental diets was calculated according to the local market price of ingredients and rabbit live body weight as following: Net revenue = total revenue -total feed cost.
Collected data were subjected to statistical analysis as two factors-factorial analysis of variance using the general linear model procedure of SPSS (1998).Duncan's Multiple Range Test (1955) was used to separate means when the dietary treatment effect was significant.Hemicellulose was calculated as the difference between NDF and ADF, while cellulose was calculated as the difference between ADF and ADL.Digestible energy (DE) was calculated according to Cheek (1987) as following: DE (MJ/ kg DM) = 4.36 -0.04 x NDF%.

Chemical analysis and cell wall constituents of the experimental diets
Crude protein contents for the six rations used (G 1 -G 6 ) were 16. 04, 16.11, 16.12, 14.48, 14.41 and 14.42 %, respectively (Table 2).These variations were related to differ in ingredients that used in ration formulations, also to study the effect of decreasing protein level on rabbit performance.The 90% of protein requirement containing diets showed slightly increase in cellulose contents while hemicellulose was slightly decreased.These data may suggest that alterations in metabolism involved in adaptation to a diet high in hemicellulose indicating an increased propensity for oxidative metabolism occurred in the intestine.Similar result was observed by Weber et al. (2010).While NDF, ADF and ADL values of the experimental rations showed insignificantly variations (Table 2).

Nutrient digestibility and nutritive values of the experimental diets
The 90% of protein requirements significantly (P<0.05)improved the digestibility coefficient values of DM, OM, CP, CF and NFE digestibility and TDN, while, EE digestibility was in the same trend (Table 3).In contrast, the 100% protein without feed additives (G 1 ) showed lowest values of DM, OM, CF and NFE digestibility coefficients and nutritive valued (TDN and DCP) (Table 4).Former suggest that when CP content is low the CF should be high and therefore the digestive efficiency in the small intestine appeared higher and must lead to improve the properties of digestion.Similar results obtained in rabbit by Milis and Liamadis (2008).
Mustard seeds at 1% in rabbit diets significantly (P<0.05)increased all nutrient digestibilities and nutritive values compared to control diet (Table 3).Mustard seeds at 0.5% significantly (P<0.05)increased the DM and EE digestibilities and total digestible nutrient compared to control diet (Table 3).These data may be due to the ability of Sinapisalba on the formation and/or release of antimicrobial substances as reported by Luciano et al. (2010).Also, may be due to the mustard oil enhancement of aerobic mesophilic and lactic acid bacteria as noticed by Lemay et al. (2002).
The 90% of protein requirement with 1 % mustard seeds (G 6 ) showed the best digestion coefficients of DM, OM, CP, EE and NFE and TDN value (Table 4).On the other hand 100% protein with 1 % mustard seeds (G 3 ) showed the best value of DCP.The first result with low dietary protein means that the high dietary fiber promotes the digestion properties.Similar results wasobtained by (Milis and Liamadis 2008).The second result with high dietary protein may be due to the glycosides that are derived from methionine, phenylalanine, or tryptophanin mustard oil (Chavadejet al., 1994).On the other hand these results may be due to the ability of microorganisms to synthesize sulfur-amino acids that has been repeatedly demonstrated by sulfur (Georgievskiiet al., 1982).In other words these results in the two cases may be due to the aromatic isothiocyanates isolated from Sinapisalba containing phenethyl-benzyl-and benzoyl-groups might be useful in the development of novel preventive and therapeutic agents against diseases caused by harmful intestinal bacteria, as reported by Kim and Lee (2009).
Adding 0.5% or 1% mustard seeds showed insignificant effects on feed intakes of DM, TDN and DCP as well as CP intake (Table 5).This insignificant results may be indicate that mustard seeds is one of some dietary protein, whole grain, and fiber that promote satiety and either reduce energy absorption or stimulate energy expenditure, as explained by Astrupet al. (2010).
The interaction between the protein and mustard seeds levels significantly (P<0.05)increased the all nutrient digestibility coefficients (DM, OM, CP, CF, EE and NFE) and nutritive values (TDN and DCP) (Table 4).These significant results may be due to the high fiber related with the low protein level used (Milis and Liamadis 2008) as well as the volatile compounds of mustard hydrodistillates exhibited great potential of antibacterial activity as reported by Blazevićet al. (2010).

Growth performance of the experimental groups
The experimental diets of protein levels showed insignificant effects on final weight, total body weight gain, average daily gain and feed intake as DM, TDN, CP, DCP as well as feed conversion of DM, TDN, CP and DCP, respectively (Table 5).Inclusion of Mustard seeds in the rabbit diets at 0.5% or 1% significantly (P<0.05)improved the final weight, total weight gain, average daily gain and feed conversion compared to control diet (Table 5).These results indicate that mustard seeds may be able to be genetically modified to express high levels of beta-carotene, a precursor to vitamin A as reported by Chow et al. (2010).
Supplementation Mustard seeds at 1% level significantly (P<0.05)increased the total body weight gain and average daily gain by 24.3% while at 0.5% significantly (P<0.05)increased the total body weight gain and average daily gain by 14.5% compared to the control group (Table 6).The interaction between the protein and mustard seeds levels significantly (P<0.05)increased the final weight, weight gain, average daily gain and feed conversion (Table 6).These results may be due to the enzymatically synthesized natural antioxidant of mustard that has nutritional properties as cleared by Kanjilalet al. (1999).The 90% of protein requirement with 1% mustard seeds (G 6 ) recorded the best values of final weight, total weight gain, average daily gain and feed conversion (Table 6).In other words this result may due to detailed characterization of single antioxidant components of Sinapis alba seeds (i.e., polyphenols, carotenoids, chlorophylls, and ascorbic acid) as noticed by Salvatore et al. (2005).

Carcass characteristics of the experimental groups
The variety of protein or mustard seeds levels showed insignificant (P>0.05)effects on digestive tract weight, total inedible offal's weight, carcass weight and chemical analysis of the 9, 10 and 11 th ribs (Table 7).Inclusion mustard seeds in rabbit diets clearly decreased the dressing percentages by increasing the level of mustard seeds in rabbit diets.This result may be due to the presence of some fatty acids in mustard oil that are not usually present in edible oils and fats that reduced calorie fats as reported by Kanjilalet al. (1999), and by Sengupta and Ghosh (2010) who reported that mustard oil had beneficial effects on energy balance.The protein or mustard seeds supplementation levels showed insignificant effects on digestive tract (% of SW), liver, carcass weight and chemical analysis of the 9,10 and 11 th ribs (CP & EE contents), while showed significantly (P<0.05)interaction on dressing percentages and chemical analysis of the 9,10 and 11 th ribs (DM & ash contents), (Table 8).Rabbits that received 90% protein with 1% mustard seeds (G 6 ) recorded the best values of carcass weight.This result may be due to the mustard seed content of monounsaturated fatty acids that contribute to decelerating obesity and the metabolic syndrome as reported by Misraet al. (2010) andEskinet al. (2007).Or may be due to the high resistance of Sinapisalba to trypsin digestion (González De La Peña et al., 1996).

Economical evaluation
The economical efficiency of dietary treatments is presented in Table (9).The profitability of using mustard seeds depends on upon the price of tested diets and the rabbit's growth performance.Lowering the dietary protein level from 100% to 90% ofrequirements decreased the total cost by 4.63%.Dietary 90% of protein requirements with 0.5% or 1% mustard seeds showed the higher value ofnet revenue, economical efficiency and relative economic efficiency, as well as the lower value of feed cost/ kg live body weight (LE).These results was due to the high weight of carcass and growth performance values that deflexed the high nutritional value of mustard seeds levels of beta-carotene, a precursor to vitamin A as reported by Chow et al., (2010).Rabbits that received 90% protein with 1% mustard seeds (G 6 ) recorded the best values of carcass weight.Rabbits fed on diet 90% of protein requirements with 1% mustard seeds (G 5 ) diet recorded the highest value of relative economic efficiency (155%) and the lowest value of feed cost/ kg live body weight (5.23 LE).These results are agreement with those obtained by Ibrahim et al. (2009) when rabbits fed on two different levels of energy supplemented with Artemisia herba-alba, Matricariarecutita L. and Chrysanthemum coronarium as herb mixture.

Conclusion
Dietary 90% of protein requirements with 0.5% or 1% mustard seeds showed the high value ofnet revenue, economical efficiency and relative economic efficiency, the lower value of feed cost/ kg live body weight (LE) as well as the best parameters of digestibility coefficients and growth performance.Mustard seeds at 1% significantly (P<0.05)increased the total body weight gain and average daily gain by 24.3% while at 0.5% significantly (P<0.05)increased the total body weight gain and average daily gain by 14.5% compared to the control group.Our data suggest that mustard seeds can be considered effectively growth promoter for improving the utilization of low protein diet.  2 Include medication, vaccines, sanitation and workers.
3 include the feed cost of experimental rabbit which was LE 15/ rabbit + management. 4Body weight x price of one kg at selling which was LE 22.
5 net revenue per unit of total cost. 6Assuming that the relative economic efficiency of control diet equal 100. 7Feed cost/kg LBW = feed intake * price of kg / Live weight.

Table 3 .
Main effects of protein and supplementation levels on nutrient digestibility and nutritive values of the experimental diets

Table 4 .
Effect of interactions between protein and supplementation levels on nutrient digestibility and nutritive values of the experimental diets

Table 5 .
Main effects of protein and supplementation levels on growth performance of the experimental groups

Table 6 .
Effect of interactions between protein and supplementation levels growth on performance of the experimental groups

Table 7 .
Main effects of protein and supplementation levels on dressing percentages, carcass cutsand chemical analysis of the 9,10an 11 th ribs of the experimental groups

Table 8 .
Effect of interactions between protein and supplementation levels on dressing percentages, carcass cutsand chemical analysis of the 9,10an 11 th ribs of the experimental groups Means in the same row having different superscripts differ significantly (P<0.05).

Table 9 .
Economic evaluation of the experimental groups