UTILIZATION OF FERMENTED SORREL (Hibiscus sabdariffa L.) SEED MEAL BY WEANER RABBITS

*Department of Animal Production and Health, Federal University, Wukari, Taraba State, Nigeria. Phone: 08066320686: Email: rjwafari@gmail.com Department of Animal Science and Range Management, Modibbo Adama University of Technology, Yola, Adamawa State, Nigeria. Phone: 08135999002. Email: talk2moseshannison@gmail.com Department of Animal Science and Range Management, Modibbo Adama University of Technology, Yola, Adamawa State, Nigeria. Phone: 08032357471 Email: abdullahi324@gmail.com 3Department of Animal Health and Production Technology, Adamawa State College of Agriculture, Ganye, Adamawa State, Nigeria. Phone: 07031320840. Email: litarimbuka@gmail.com


INTRODUCTION
Soybean meal (SBM) has been recognized as a conventional protein source in the formulation of poultry and rabbit ration Tang et al. (2012). However, high cost of SBM recently has necessitated animal nutritionists to search for alternative sources that are cheaper and readily available. Sorrel seed (Hibiscus sabdariffa L.) is consider as one of such plant. The plant is well adapted to both Guinea and Sudan savanna vegetation of Nigeria (Alagbejo, 2000). The raw seed on dry matter basis contains 35.90% crude protein, 10.14% ether extract, 10.09% ash and 15 -17% crude fiber (Dashak and Nwanegbo 2002;Kwari et al., 2011) and also appreciable amount of minerals such as phosphorus, calcium and magnesium (Ismail et al., 2008). The seed has also been reported to possess anti-oxidative and antihypercholesterolemic properties (Ismail et al., 2008;Mahadevan et al. 2009). However, the seed have been reported to contain anti-nutritional factors such as total phenols, tannins and phytic acid, saponins and alkoloids which have limited its utilization by monogastric animals Wafar, 2013). Hence, proper processing of the seed to aid its utilization by non -ruminant animals is necessary.
Several processing methods have been employed towards reducing the anti-nutritional factors in sorrel seeds to make it useful especially to monogastric animals Wafar 2013 andAshom et al., 2014). These authors concluded from their studies that sorrel seed can be improved through processing. One of the processing methods focused in this study is fermentation. According to Yakubu et al. (2017) fermentation is the breaking down of complex organic substances into simpler ones through the action of enzymes. Through fermentation, B-vitamin is synthesized, mineral extraction abilities increased, as well as reduction in anti-nutrient and fiber contents of feed materials (Oboh, 2006;Aro et al., 2008;Badau et al. (2015). A study by Yakubu et al., (2017) showed that natural fermentation of Jatropha seed improved its utilization in broiler chicken. Recently, Tuluen et al. (2011), reported that natural fermented mucuna seed replaced soyabeans meal in broilers chickens' diet up to 20% without any deleterious effects on their performance. These reports suggest that natural fermentation could be a promising method in detoxifying anti-nutritional factors in the leguminous seed. This study was therefore conducted to evaluate the growth performance, carcass yield and internal organs characteristics of weaner rabbits fermented sorrel seed meal.

MATERIALS AND METHODS
Sorrel seeds were procured from Yola market, Adamawa State, Nigeria. 50kg kapok seed was cleaned of debris and cooked for one hour using metallic pot. The pot was placed on a tripod stand having firewood as a source of heat. The timing of the cooking started at the point of boiling after the seeds were introduced. The water was drained immediately after cooking and the seeds packed in a polythene bag to allow natural fermentation to take place. The fermentation process lasted for 120 hours (5days). The fermented sorrel seeds were sundried and milled using hammer milling machine to produce fermented sorrel seed meal (FSSM).

EXPERIMENTAL DIETS, DESIGN AND MANAGEMENT
Five experimental diets containing 0, 10, 20, 30, and 40% FSSM were formulated (Table 1). Forty (40) weaner rabbits with an average weight of 556.89 ±0.10g were randomly assigned to the five treatment groups of 8 rabbits per treatment replicated four times with 2 rabbits per replicate in a completely randomized design. The rabbits were housed in cage measuring 150cm x100cm x120cm in a three-tier hutch system raised 90cm above the floor. The cages were fitted with aluminum feeders and drinkers. The animals were treated against internal and external parasites using Endovef® (Ivermectin) at the dose of 0.3 mg/kg subcutaneously and also treated prophylactally against coccidiosis with Amprole 200® according to the manufacturer's prescription.

GROWTH PERFORMANCE MEASUREMENTS
Feed intake was determined as the difference between the quantity of feed offered and feed leftover. Similarly, total body weight gain was determined as the difference between the final body weight and initial body weight recorded at the beginning of experiment. Feed conversion ratio was calculated the ratio of feed intake to weight gain.

CARCASS AND INTERNAL ORGANS EVALUATION
One rabbit from each replicate was randomly selected for carcass and internal organs evaluation according to the method described by Yakubu and Wafar (2014). The rabbits were weighed individually, slaughtered and de-pelted completely to obtain pelt weight. The internal organs were removed carefully and weighed using electronic sensitive scale and expressed as percentages of their live bodyweight. The dressing percentage was calculated as a ratio of carcass weight and live weight multiplied by 100.

LABORATORY ANALYSIS
The proximate composition of raw, fermented sorrel seed meal and experimental diets were determined according to methods described by AOAC (1990).

STATISTICAL ANALYSIS
Data generated were subjected to one-way analysis of variance (ANOVA) according to Steel and Torrie, (1980) and significant differences between treatment means were separated using Duncan's Multiple Range Test (Duncan, 1955). The DM value observed were within the range of 87.90 -94.30% for raw seeds and differently processed sorrel seed by Duwa et al. (2012). The increase in DM content of sorrel seed meal after processing has been reported by Ari et al. (2015). Higher CP content observed in fermented seed could possibly be due to the modification effect of the fermentation process that leads to crude protein improvement. The CF content of the raw and fermented sorrel seed is within the value of 13.01 -15.50% CF reported by Duwa et al. (2012) for raw and differently processed sorrel seed meal, but higher than the range of 5.55 -6.16% reported by Ari et al. (2015).The variations in the nutrient composition when compared to other studies could be attributed to the differences in agronomic practices, laboratory analysis and edaphic factors (Taiwo et al., 2005).

RESULTS AND DISCUSION PROXIMATE COMPOSITION OF RAW AND FERMENTED SORREL SEED MEALS
The result of the anti-nutritional factors (ANFs) in the seed showed that the raw seed has the highest concentration of all the ANFs. It is an indication that fermentation influenced the concentration of ANFs and increased the nutrient composition of sorrel seed, but did not influence the complete removal of the ANFs. The finding is in line with the report of Makkar et al. (1998), Wafar (2013) and Yakubu et al. (2017) when they subjected tropical legume seeds to different processing methods and recorded partial reduction of ANFs in the seeds

GROWTH PERFORMANCE OF WEANER RABBITS FED FERMENTED SORREL SEED MEAL
The result of the growth performance of rabbits fed processed fed fermented sorrel seed meal is presented in Table   III. The result showed no significant differences (P>0.05) between the dietary treatments for the parameters measured.
Final body weight varied from 1770.12 -1784.91g/rabbit. Average daily feed intake (ADFI) ranged from 100.56g in T2 to 102.56g in T4 while average daily weight gain (ADWG) and Feed conversion was between 21.65g in T3 to 21.94g in T1 and 4.62 in T1 and T2 to 4.74 in T4. The daily feed intake of rabbits observed were higher than range of 23.78 to 24.04g/day reported by Amaefule et al. (2004) and 64.72 -76.07 g/day reported by Biobaku and Dosumu, (2003) for rabbit raised under tropical conditions. However, the values are within the range of 91.25 -175.41 reported by Kpanja et al. (2016) for rabbits fed fermented castor seed meal. Also, the daily weight gain and final body weight were higher than the range of 16.19 to 20.11 g/day and 1154.00 to 1185.63g reported by Ani and Ugwuowo, (2011) and Yakubu and Wafar, (2014). The non-significant differences in growth parameter measured could be due to the fact that fermentation reduced the ANFs in the sorrel seeds to a level that could not cause deleterious effect on the rabbit.

CARCASS CHARACTERISTICS AND INTERNAL ORGANS WEIGHTS OF WEANER RABBITS FED FSSM
The results of carcass characteristics and internal organs weights are shown in Table IV. The result showed no significantly (P>0.05) different in all the parameters evaluated. This is similar to the finding of Tuleun et al. (2011) who reported no significant effect in carcass characteristics of broiler chicken fed naturally fermented mucuna seed meal. The live body weight values obtained in this study are higher than the range 1603.00 -1621.00g reported by Tarimbuka et al. (2017) but within the range 985.08-1960.08 recorded by Omoikhoje et al. (2016). The dressed weight observed is higher than the range of 550 -820 g reported Tarimbuka et al. (2017) and 499.0-592.00 g recorded by Wafar and Tarimbuka, (2016). The result of internal organs expressed as percentage of live weight were not significantly (P>0.05) affected by the level of FSSM in the diets. This suggests that cooking and fermentation process have rendered the level of anti-nutrients in raw sorrel seed inactive. Several studies have shown that the presence of anti-nutrients in high concentration causes growth depression and hypertrophy of organs such as liver and kidney. It is evident that feeding weaner rabbit with fermented sorrel seed meal did not affect these organs.

CONCLUSION
The result from this study showed that fermentation improves the crude protein content of sorrel seed meal as well and as well reduced the anti-nutritive factors. The growth performance parameters, carcass characteristics and internal organs were similar across the dietary treatments. In conclusion, fermented sorrel seed meal can be included in rabbits' diet up to 40% levels without adverse effect on performance, carcass characteristics and internal organs of rabbits.