Response of Growing Rabbits to Diets Containing Different Levels of Protein and Radish ( Raphanus sativus L ) Seeds

This work aimed to study the effect of two different levels of ration protein supplemented with Radish (Raphanus sativus L) seeds (RS). Rabbits were classified into four equal groups (G1-G4). The1 and 3 groups received basal ration with 100 % and 90 % of protein requirement level and served as first and second control respectively. The 2 and the 4 groups received basal ration with 100 and 90% of protein supplemented with RS at the level 1.5%, respectively. The 90% of protein level significantly (P<0.05) increased the DM, OM, CP, CF and EE digestibility and TDN value as well as significantly (P<0.05) decreased the digestible CP in comparison with the100% requirements. The 90% of protein level significantly (P<0.05) increased the TDN intake. The 100% of protein level significantly (P<0.05) improved the feed conversion (g intake /g gain) of DM, TDN and DE (kcal/h/d). The 90% of protein level insignificantly (P>0.05) improved the final weight, total body weight gain, ADG (g), feed intake as DM, DCP, DCP (g/day) and DE (kcal/h/d) and feed conversion (g intake /g gain) of CP in comparison with the 100% of protein requirements. Radish seeds (RS) at 1.5% level significantly (P<0.05) increased all nutrient digestibility coefficients and nutritive values compared to the control diet. There were significant (P<0.05) interactions between the protein and RS levels on all nutrient digestibility coefficients (DM, OM, CP, CF, EE and NFE) and nutritive values of TDN and DCP. The 90% of protein level + 1.5 % (RS) showed the best digestion coefficients of DM, OM, CP, CF, EE and NFE and TDN value. The 100% of protein level + 1.5 % Radish seeds (G2) showed the highest value of DCP. Supplementation Radish seeds at 1.5% level significantly (P<0.05) improved feed intake as DCP and TDN (g/day) while, it significantly (P<0.05) decreased feed conversion (g intake /g gain) of TDN. Adding Radish seeds at 1.5% level insignificantly (P>0.05) increased the final weight, total body weight gain, average daily gain (ADG); feed intake as DM, CP (g/day) and DE (kcal/h/d) and feed conversion (g intake /g gain) of DM, CP and DE (kcal/h/d) compared to the control diet. The 90% of protein requirement with supplementation Radish seeds at 1.5% level recorded the best values of final weight, total body weight gain, average daily gain, feed intake (g/h/day) of DM, DCP, TDN and DE and feed conversion feed conversion of DM, CP and TDN (g intake/ g gain) and DE (Kcal intake /g gain). There were interactions between protein and supplementation levels on DM, DP, TDN and DE intakes and feed conversion (g intake/ g gain) of DM, CP, TDN and DE. There were significant (P<0.05) interactions between protein and supplementation levels on carcass characteristics such as www.ccsenet.org/jas Journal of Agricultural Science Vol. 4, No. 3; 2012 ISSN 1916-9752 E-ISSN 1916-9760 282 digestive tract; edible offal's weight (head and testes, weight and % of SW) and dressing percentages expressed as CW1/ SW and DM of the 9, 10 and 11 ribs. Rabbits fed on diet containing the 90% of protein requirements with 1.5% (RS) showed the highest values of net revenue, economical efficiency and relative economic efficiency, Supplementation of radish seeds in rabbit diets improved all nutrient digestibility, growth performance, dressing percentages and economical efficiency indicating that radish seeds can be used as growth promoter for improving the utilization of low protein in rabbit diets.

The 90% of protein level significantly (P<0.05)increased the DM, OM, CP, CF and EE digestibility and TDN value as well as significantly (P<0.05)decreased the digestible CP in comparison with the100% requirements.The 90% of protein level significantly (P<0.05)increased the TDN intake.The 100% of protein level significantly (P<0.05)improved the feed conversion (g intake /g gain) of DM, TDN and DE (kcal/h/d).The 90% of protein level insignificantly (P>0.05)improved the final weight, total body weight gain, ADG (g), feed intake as DM, DCP, DCP (g/day) and DE (kcal/h/d) and feed conversion (g intake /g gain) of CP in comparison with the 100% of protein requirements.
Radish seeds (RS) at 1.5% level significantly (P<0.05)increased all nutrient digestibility coefficients and nutritive values compared to the control diet.There were significant (P<0.05)interactions between the protein and RS levels on all nutrient digestibility coefficients (DM, OM, CP, CF, EE and NFE) and nutritive values of TDN and DCP.The 90% of protein level + 1.5 % (RS) showed the best digestion coefficients of DM, OM, CP, CF, EE and NFE and TDN value.The 100% of protein level + 1.5 % Radish seeds (G 2 ) showed the highest value of DCP.Supplementation Radish seeds at 1.5% level significantly (P<0.05)improved feed intake as DCP and TDN (g/day) while, it significantly (P<0.05)decreased feed conversion (g intake /g gain) of TDN.Adding Radish seeds at 1.5% level insignificantly (P>0.05)increased the final weight, total body weight gain, average daily gain (ADG); feed intake as DM, CP (g/day) and DE (kcal/h/d) and feed conversion (g intake /g gain) of DM, CP and DE (kcal/h/d) compared to the control diet.The 90% of protein requirement with supplementation Radish seeds at 1.5% level recorded the best values of final weight, total body weight gain, average daily gain, feed intake (g/h/day) of DM, DCP, TDN and DE and feed conversion feed conversion of DM, CP and TDN (g intake/ g gain) and DE (Kcal intake /g gain).There were interactions between protein and supplementation levels on DM, DP, TDN and DE intakes and feed conversion (g intake/ g gain) of DM, CP, TDN and DE.There were significant (P<0.05)interactions between protein and supplementation levels on carcass characteristics such as

Introduction
Radish (figle) used in this study is the dried seeds of Raphanus sativus L (RS), belonging to the Brassicaceae family.Recently, it has been found that some medicinal plants have growth enhancing properties.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 viability (El-Hindawy et al., 1996).The found inhibitors with their characteristic profiles in radish be useful in biochemical and pathophysiological on granulocyte proteinases and enzymes of the coagulation and fibrinolytic pathways (Ghayur et al., 2005).Raphanus sativus L has laxative and gastrointestinal and uterine tone modulatory activities (Zhang et al., 2010).Raphanus sativus L may be used for the prevention and treatment of neuro degenerative diseases (Bae et al., 2010).Raphanus sativus L provides protection by strengthening the antioxidants like glutathione and catalase (Chaturvedi, 2008).Raphanus sativus L extracts rich in many antioxidant compounds, were safe and successfully countered oxidative stress and provided protection against the toxicity (Salah-Abbès et al., 2009).The antioxidant properties of Raphanus sativus L via induced bile flow in rats (Barillari et al., 2006).Raphanus sativus L exerts potential chemo preventive efficacy and induces apoptosis in cancer cell lines through modulation of genes involved in apoptotic signaling pathway (Beevi et al., 2010).Radish extract may partially prevent hepatotoxicity, possibly by indirectly acting as an antioxidant by improving the detoxification system (Baek et al., 2008).Radish extract contains several compounds that are able to inhibit mycotoxin toxicity (Ben Salah-Abbès et al., 2008).
Low dietary protein requirements may cause imbalance in the body metabolism and growth performance.The hypothesis that sulfur compounds has ability to repair the tissue defection protein of the cells (Georgievskii et al., 1982).Sulfur is indispensable for synthesis of certain compounds-mainly sulphated mucopolysaccharides in the body (Georgievskii et al., 1982).The requirements of sulfur containing amino acids by monogastric animals is 3-4% of the feed protein, and the requirement for sulfur is 0.6-0.8% of the protein (Georgievskii et al., 1982).There are antifungal proteins, isolated from Radish seed or leaves, which consist of 50 or 51 amino acids and belong to the plant defensin family of proteins (Schaaper et al., 2001).The complete primary structure of Japanese radish component was established by sequencing of the whole protein and of peptides generated by protease digestion (Obata et al., 1995).Sulfur-radish extract may prevent hepatotoxicity, possibly by indirectly acting as an antioxidant by improving the detoxification system (Baek et al., 2008).This work aimed to evaluate the efficacy of Radish (Raphanus sativus L) seeds as feed additive to improve the utilization of low protein rabbit diet as well as growth performance.

Experimental animals and feeds
A total number of 36 male New Zealand White rabbits aged 5 weeks with an average body weight of 745.5 ± 20.62 g, were divided into four 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).Radish (Raphanus sativus L) seeds were used as feed additive.The feeding period was extended for 56 days, and the experimental groups were classified as follow: Group 1 basal diet with 100 % protein requirement and served as control (G1), Group 2 basal diet with 100 % protein requirement + 1.5% radish seeds (G2), Group 3 basal diet with 90 % protein requirement and served as control (G3) and Group 4 basal diet with 90 % protein requirement + 1.5 % radish seeds (G4).
Rabbits were individually housed in galvanized wire cages (30 x 35 x 40 cm).Stainless steel nipples for drinking and feeders allowing recording of 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 managemental conditions and were individually weighed.Feed consumption was individually recorded weekly during the experimental period.

Digestibility trials
All rabbits were used in digestibility trials over period of 7 days to determine the nutrient digestibility coefficients and nutritive values of the tested diets.. Feed intake of experimental rations and weight of feces were recorded daily.Representative samples of feces was were dried at 60C for 48 hrs, ground and stored for chemical analysis later.

Carcass traits
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 included head, liver, heart, testes and kidneys.These were removed and individually weighed.Full and empty weights of digestive tract were recorded and digestive tract contents were calculated by differences between full and empty digestive tract.Weights of edible and external offal's were calculated as percentages of slaughter weight (SW).Hot carcass was weighed and divided into fore, middle and hind parts.The 9, 10 and 11 th ribs were frozen in polyethylene bags for chemical analysis later.The best 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'Mara et al. (1979).

Analysis procedures
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).Hemicellulose was calculated as the difference between NDF and ADF, while cellulose was calculated as the difference between ADF and ADL.
Diets were offered pelleted and the diameter of the pellets was 4 mm.

Economical evaluation
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.

Statistical analysis
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.

Chemical analysis and cell wall constituents of the experimental diets
Data of Table (2) showed that dietary treatment was isocaloric but differed in protein contents.Protein contents for the tested rations (G 1 -G 4 ) was 16.10, 16.05, 14.52 and 14.49 %, respectively.The 90% of protein containing diet showed slight decrease in cell wall constituents (NDF, ADF, ADL and hemicellulose contents).On the other hand cellulose content of the experimental rations showed approximately the same trend (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.These data may suggest that alterations in metabolism involved in adaptation to a diet high in hemicellulose and pectin content of radish indicating an increased propensity for oxidative metabolism occurred in the intestine, similar result observed by Nishimura et al. (2000).

Nutrient digestibility and nutritive values of the experimental diets
Rabbits fed on diets containing 90% protein level showed significant improvement in nutrient digestibilities (P<0.05)DM, OM, CP, CF and EE digestibility and TDN value (Table 3).Increase in NFE digestibility was insignificant (P>0.05),however, digestible crude protein was significantly decreased (P<0.05) in comparison with 100% energy requirements.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 (Milis and Liamadis, 2008).
Inclusion of Radish seeds at 1.5% in rabbit diets significantly (P<0.05)increased all nutrient digestibility coefficients and nutritive values compared to the control diets (Table 3).There were significant (P<0.05)interactions between the protein and RS levels on all nutrient digestibility coefficients (DM, OM, CP, CF, EE and NFE) and nutritive values of TDN and DCP (Table 4).
Rabbits which received 90% of protein requirement + 1.5 % Radish seeds (G 4 ) showed the best digestion coefficients of DM, OM, CP, CF, EE and NFE and TDN value (Table 4).On the other hand rabbits that received 100% of protein requirement + 1.5 % Radish seeds (G 2 ) showed the highest value of DCP.These results may be due to the improvement in the epithelial lining, the number of enterocytes as well as increased the numbers of goblet cells that secrete mucin in gut in responses to Radish seeds, as has been observed previously by Sipos et al. (2002).

Growth performance of the experimental groups
Data of Table ( 5) indicate that feeding rabbits on 90% of protein requirements did not have any significant effect on improvement of the final weight, total body weight gain, ADG (g); feed intake as DM, DCP, DCP (g/day) and DE (kcal/head/day) and feed conversion (g intake/ g gain) of CP in comparison with 100% of protein requirements.However, 90% of protein requirements significantly (P<0.05)increased TDN intake.On the other hand, rabbits which received 100% of protein requirements showed significantly (P<0.05)improved feed conversion (g intake/ g gain) of DM, TDN and DE (kcal/head/day).The insignificant improved at the lesser protein level indicated that decreasing the dietary protein level be against the level of fiber which leads to improve the properties of digestion of rabbits, similar results obtained in rabbit by Gidenne (1992) who reported that adaptation to a high-fiber diet resulted in a higher digestive volume for colon and caecum, related to an improved degradation of cell wall.Furthermore, digestive efficiency in the small intestine appeared higher for rabbits adapted to a high-fibre diet than that for rabbits initially fed on a low-fibre diet, similar results noticed by Rigó (1982).
Though the inclusion of RS at 1.5% in rabbit diet increased the marketing weight, total body weight gain and average daily gain by 5.55% 7.81% and 7.80%, respectively compared to the control group, the increase was not significant(P>0.05).However, the inclusion 1.5% Radish seeds significantly improved (P<0.05) feed intake as DCP and TDN (g/day) while it significantly (P<0.05)decreased feed conversion (g intake /g gain) of TDN.These results may be due to the lactic acid bacterial strain, which is derived from Raphanus sativus L. fermentation, holds great promise for use in probiotics and as a food additive since it can reduce the number of some pathogenic bacteria through production of lactic acids, similar results obtained by Chon and Choi (2010).6) revealed that there were no interactions between protein and supplementation levels (PxS) on final weight, total body weight gain, average daily gain (ADG) and CP intake (g/head/day) and feed conversion (g intake/ g gain) of DCP.While, there were interactions between protein and supplementation levels (PxS) on DM, DP, TDN and DE intakes and feed conversion (g intake /g gain) of DM, CP, TDN and DE.These interactions results may be due to that Raphanus sativus L has mediated partially gastrointestinal effects partially through cholinergic receptors in rabbit tissues and providing a scientific basis for its use in gut, as noticed by Ghayur and Gilani (2005).

Data of Table (
Rabbits received 90% of protein requirement and 1.5% supplementation of Radish seeds (G 4 ) recorded the best values of final weight, total body weight gain, average daily gain, feed intake (g/h/day) of DM, DCP, TDN and DE and feed conversion feed conversion of DM, CP and TDN (g intake /g gain) and DE (Kcal intake /g gain).These results in agreement with those found by Jung et al. (2000).Who recorded that RS stimulates gastrointestinal motility through activation of muscarinic pathways via induced ileal contraction It may be due to the antibacterial activity of Radish against food borne and resistant pathogens, such as Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella typhimurium, Enterobacter aerogenes, Enterobacter cloacae, and Escherichia coli, as reported by Beevi et al. (2009).

Carcass characteristics of the experimental groups
Main effects of protein and supplementation levels on dressing percentages, carcass cuts and chemical analysis of the 9,10 an 11 th ribs of the experimental groups are presented in Table (7).The results indicate that that protein or supplementation levels of Radish seeds had no significant effect (P>0.05) on inedible offal's (weight and % of SW); digestive tract empty body weight (EBW); edible offal's (head, liver, heart, kidneys and testes (weight and % of SW); carcass weight; dressing percentages; carcass cuts and chemical analysis of the 9,10 and 11 th ribs although protein level or Radish seeds in rabbit diets slightly decreased dressing percentages.These results in agreement with those obtained by Satoh et al (1993) who noted that the hypocholesterolemic action of radish may have been due to the inhibition of intestinal absorption of both cholesterol and bile acids.There were significant (P<0.05)interactions between protein and supplementation levels (PxS) on digestive tract; edible offal's (head and testes, weight and % of SW); dressing percentages expressed as CW 1 / SW and DM of the 9,10 and 11 th ribs (Table 8),while there were no interaction between protein and supplementation levels (PxS) on the other carcass parameters.Rabbits which received 90% protein and 1.5% supplementation of radish seeds (G 4 ) recorded the best value of carcass weight.These results in agreement with those noticed by Kwon et al. (2009) who indicated that the methylisogermabullone purified from radish differently regulates the spontaneous contractility (tone and/or amplitude) of gastrointestinal segments according to the region of gut and orientation of smooth muscles, and these contractile responses of gastrointestinal tracts by activation of acetylcholinergic receptors.

Economical evaluation
The economical efficiency of dietary treatments is presented in Table ( 9).The profitability of using Radish seeds as supplementation depends on upon the price of tested diets and the growth performance of rabbits fed these diets.Costing of one kg feed, (LE) decreased by 9.10% (G 3 ) and 6.49% (G 4 ) compared to control diet (G 1 ).Rabbits fed diet containing 90% protein requirements with 1.5% Radish seeds (G 4 ) showed the highest values of net revenue (26.64 LE), economical efficiency (0.9064) and relative economic efficiency (111.6%), with the lowest value of feed cost/ kg live body weight (4.08 LE).These results are due to the high weight of carcass and growth performance values that reflect the high nutritional value of radish seeds.Similar results in using golden mustard seeds were reported by (Chow et al., 2010).These results are in agreement with those obtained by Ibrahim et al. (2009) when rabbits were fed on two different levels of energy supplemented with Artemisia herba-alba, Matricaria recutita L. and Chrysanthemum coronarium as herbs mixture.

Table 2 .
Chemical analysis and cell wall constituents of the experimental diets

Table 3 .
Main effects of energy and supplementation levels on nutrient digestibility coefficients and nutritive values of the experimental diets Means in the same row within each treatment having different superscripts differ significantly (P<0.05).SEM, standard error of the mean.

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

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

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

Table 7 .
Main effects of energy and supplementation levels on carcass characteristics of the experimental groups * In edible offal's: included fur, ears, legs and blood.**Edible offal's: included head, liver, heart, kidneys and testes.Empty body weight (EBW) = slaughter weight -digestive tract contents.

Table 8 .
Effect of interactions between energy and supplementation levels on carcass characteristics of the experimental groups , b and c: Means in the same row having different superscripts differ significantly (P<0.05).SEM, standard error of the mean.* In edible offal's: included fur, ears, legs and blood.**Edible offal's: included head, liver, heart, kidneys and testes.Empty body weight (EBW) = slaughter weight -digestive tract contents. a

Table 9 .
Economical evaluation of the experimental groups