An experiment was conducted on 48 New Zealand White rabbits of either sex for evaluating the effect of supplementing spirulina and thyme on nutrient digestibility and feed conversion ratio (FCR). Rabbits were randomly assigned to four treatments in three tier cages, divided into two compartments, housing six rabbits in each compartment, in controlled environmental conditions during the feeding trial of 56 days. The experiment consisted of four dietary treatments. Treatment group T1 was fed with control diet as per ICAR (2008) guidelines with concentrate mixture formulated using maize, soybean meal, ground nut cake, gram, mineral mixture and common salt. In treatment groups T2, T3 and T4, concentrate mixture as used in control group was supplemented with 5% Spirulina, 3% Thyme and 5% Spirulina plus 3% Thyme, respectively. At the end of experiment a digestibility trial was conducted for 7 days and the results revealed that digestibility of dry matter, crude protein, crude fiber and NFE of rabbits fed with supplementation of 5% Spirulina and 3% Thyme in combination was significantly higher than rabbits fed control diet. The EE and ash digestibility of rabbits under different treatments remain statistically similar. The results of the study also revealed that mean values of FCR of rabbits fed with thyme or combination of thyme with spirulina supplementation was higher than rabbits of control group or supplemented with spirulina alone.
Rabbits are animals which can thrive well on feed ingredients based on agro-industrial by-products, forages or a combination of both. Sometime sole forage feeding may result in low level of nutrient intake. Nutrient deficiency usually occur when concentrate feed are not supplemented. Feeding rabbit with concentrate feeds, as supplemental or sole can supply amino acid and other nutritional components to these animals. Animal and vegetable protein sources are mostly used as protein sources in rabbit feed. These requirements can be met with various number of ingredient combinations, which supplement each other. Spirulina and thyme are such ingredients which can be used in rabbit feed efficiently. Spirulina (Arthrospira platensis) is a blue-green micro-algae rich in protein, vitamins, essential amino acids, minerals and essential fatty acids (Belay et al., 1996). Spirulina is also a source of other compounds like β-carotene, phycocyanin and allophycocyanin with antioxidant activity, sulphated polysaccharides with anti-viral properties, and sterols, which are mainly responsible for antimicrobial activity (Wang et al., 2007). Thyme (Thymus vulgaris) is a phytogenic feed additive belonging to the Labiatae family and Thymol is the principal component and has potential anti-oxidative and antimicrobial activities (Windisch et al., 2008).
Materials and Methods
Forty eight, New Zealand White rabbits of either sex at 6 weeks of age having average body weights of 640 g were procured from Disease Free Small Animal House, LUVAS, Hisar. Rabbits were randomly assigned to four treatments in three tier cages divided in two compartments with six rabbits in each compartment (0.7m X 0.3 m X 0.9 m) in a closed room under the controlled environment. The experiment consisted of four dietary treatments with 12 rabbits in each. Experimental rabbits in treatment group T1 were fed control concentrate mixture as per ICAR, 2008 standards while in treatment T2, T3 and T4 the rabbits were fed control concentrate mixture supplemented with 5% spirulina (Arthrospira platensis), 3% thyme (Thymus vulgaris) and combined supplementation of 5% spirulina and 3% Thyme, respectively. The concentrate mixture was prepared by mixing half crushed ingredients which contained maize, soybean meal, groundnut cake, gram, mineral mixture and iodized salt (Table 1). In addition to concentrate feed, locally available barseem (Trifolium alexandrinum) was also fed ad-libitum as green fodder. The concentrate mixture and green fodder was chemically analyzed for proximate principles (AOAC, 2005). Dry matter, crude protein, ether extract, crude fibre, nitrogen free extract (NFE) and ash content of berseem on % DM basis were 14.35, 15.12, 3.26, 19.62, 45.39 and 16.61%, respectively.
Table 1: Ingredient (g/kg) and chemical composition (% DM basis) of concentrate mixture used for different dietary treatments
|Spectromix Powder premix**||1||1||1||1|
|Spectro BE: Powder premix***||1||1||1||1|
|Chemical Composition (% DM basis)|
|Nitrogen free extract||54.55||55.13||53.86||53.56|
*Mineral mixture (salt free)-Ca (32%), Cu (100 ppm), Zn (0.26%), Iodine (0.01%), P (6%), Mn (0.27%), Fe (1000 ppm) and Co (50 ppm).
**Spectromix: Powder (Ranbaxy Animal Health, New Delhi-65).Each gm contained Vitamin A-82,500 IU, Vit. D3-12,000 IU, Vit. B2-50 mg and Vit. K-10mg.Mixing rate: 100g/MT of feed.
***Spectro BE: Powder (Ranbaxy Animal Health, New Delhi-65).Each gm contained Vit.B1-8 mg, Vit.B6-16 mg, Vit.B12-80 mg, niacin- 120mg, calcium petothenate -80mg, Vit. E-160 mg, Lysine hydrochloride-10 mg, DL-methionine- 10 mg and calcium – 260mg.Mixing rate: 100g/MT of feed.
The study was carried out for a feeding period of 8 weeks. During the last week of the experiment, a digestion trial of 7 days was conducted. A daily record of feed intake, refusals and faeces voided was maintained during the digestion trial. To prevent the mixing of faeces with urine, a nylon cloth was tied over metal trays during the collection period. The representative samples of feed ingested and faeces were taken and analyzed for proximate principles (AOAC, 2005).
The data was analyzed using IBM SPSS statistics 20 software package for windows.
Results and Discussion
The results of nutrient digestibility, nutrient intake and nutritive values of ration under different dietary treatments have been presented in Table 2. The mean values of total dry matter intake were 164.52, 164.21, 162.42 and 166.41 g/d in treatment groups T1, T2, T3 and T4, respectively. The result of the study revealed that total dry matter intake was significantly higher (P<0.05) in rabbits raised with supplementation of 5% Spirulina and 3% Thyme in combination as compared to other treatment groups (T1, T2, and T3).
Table 2: Average nutrient intake and nutritive values of rations, average nutrient digestibility coefficient and FCR in rabbits under different dietary treatments
Dry matter intake (g)
Nutrient intake (g)
|Nutritive value||DCP %||10.85a±0.08||11.26bc±0.07||11.01ab±0.10||11.45c±0.09|
|Digestibility Coefficient (%)|
|Nitorgen free extract||56.84a±0.60||59.70ab±1.50||57.29ab±1.11||60.35b±1.69|
Values bearing different superscripts in a row differ significantly at P< 0.05.
The crude protein and digestible crude protein intake values in treatment groups T1, T2, T3 and T4 were 28.16, 28.12, 27.58 and 28.54; 17.86, 18.48, 17.88 and 19.05 g/day, respectively. The results of the study unveiled that crude protein and digestible crude protein were significantly higher (P<0.05) in experimental rabbits raised with supplementation of 5% spirulina and 3% thyme in combination as compared to rabbits raised under other dietary treatments. Similarly, TDN (total digestible nutrients) intake values were higher (P<0.05) in T4 (111.63) as compared to treatment groups T1, T2 and T3 (105.04, 107.74 and 105.94 respectively). The nutritional values of the ration under different dietary treatments in terms of DCP % were 10.85, 11.26, 11.01 and 11.45 % in T1, T2, T3 and T4, respectively. The results of the study indicated that supplementation of 5% spirulina and 3% thyme in combination improved DCP (digestible crude protein) per cent values significantly (P<0.05). Similarly TDN% value in the ration improved significantly (P<0.05) in T4 group which have 5% spirulina and 3% thyme combined supplementation in the concentrate. Mean digestibility coefficients of DM, CP, CF and NFE as well as nutritive values of T4 were found significantly higher (P<0.05) due to the supplementation of 5% Spirulina +3% Thyme in rabbit feed (Table 2). A significant effect of 5% Spirulina supplementation was observed on mean digestibility coefficient of CP. However Gerencser et al. (2014) reported negative influence of Spirulina and Thyme supplementation on apparent digestibility of DM, OM & CP while digestibility of EE improved. In addition our results did not confirm with those reported by Peiretti and Meineri (2009), who observed an improvement in the digestibility of the CP caused by dietary inclusion of 1% Spirulina. However, in the study by Peiretti and Meineri (2009) the inclusion level of the ingredients was not provided, the rabbits were much older than this study, they were feed-restricted, and the dietary CP content varied between control and supplemented diets. Thus, these studies followed very different protocols and the results obtained for nutrients digestibility are scarcely comparable.
However, it is assumed that the CP digestibility seems to be dependent on the inclusion levels of Spirulina. In fact, whereas the 3% Spirulina inclusion produced no adverse effect on CP digestibility (Dalle Zotte et al., 2013), increase of Spirulina to 10% and 15% (in substitution of soybean meal and alfalfa meal) resulted in a negative digestibility trend for CP (Peiretti and Meineri, 2008). Dietary Thyme inclusion level of 3% slightly improved nutritive value, whereas synergic effect of Spirulina and Thyme supplements was also evident. Additional research is thus needed, as this was the first scientific attempt to test this combination of feeding concentrate diet along with berseem as green fodder.
It can be inferred from this study that nutrient intake, digestibility of nutrients and nutritive value improved in rabbits raised with 5% Spirulina + 3% Thyme supplementation in their concentrates.