Commercial oil of Nigella sativa as growth promoter in lambs rations

This study aimed to investigate the impact of supplementing different levels of Nigella sativa oil in rations of growing lambs. In a feeding experiment lasted 90 days, 18 growing Ossimi lambs (6-7 months old) were randomly divided by weight into three equal groups (6 animals each). Individual animals in all groups were fed a uniform total mixed ration, offered at 3% of body weight, where the first group was without supplement (R1), while Nigella sativa oil was supplemented at 0.1 (R2) and 0.2% (R3) of dietary DM. Results indicated that additions of N. sativaoil didn’t influenced feed intake, but it increased average body weight gain and feed efficiency. Nutrients digestibility values and dietary nitrogen utilization were higher with N. sativaoil rations than control. Ruminal fermentation parameters showed comparable pH values among groups at 0, 3 and 6 hrs. of feeding. Ruminal NH3-N concentration was lower and TVFA concentration was higher for animal fed R2 and R3 rations than control. It’s concluded that N. sativa oil could be added at 0.2 % of the daily feed as a natural growth enhancer of lambs.


Introduction
In animal production, antibiotics are commonly fed to animals to prevent disease and metabolic disorders, as well as improve feed efficiency.However, the World Health Organization classifies the antibiotic resistance as one of the highest impendence to human health.So, there is a need for use alternative additives instead of antibiotics in animal feeding (1) like essential oils which considered safe for animal consumption followed by humane, and recognized as safe (2) in the USA.The antimicrobial properties of EO have been demonstrated against a wide range of microorganisms, including bacteria, protozoa and fungi (3)(4)(5) which may lead to improve nutrients digestibility.Several experiments suggested that the addition of plants or plant extracts rich in bioactive compounds to ruminant rations might have beneficial effects on ruminal fermentation, thus enhancing degradation processes.Whereas, (6)(7)(8) indicated that essential oils (EO) can be used as growth promoters and have antimicrobial properties which modulate ruminal fermentation and improve nutrient utilization in ruminants.
Nigella sativa is one of the very important medicinal plants, which used for centuries in Middle East as a healer of many complains and disease (9) and is commonly known as black seed which its oil is containing linoleic 60%, oleic 22% and palmitic 12% as major fatty acids (10).Also, it can be used as antioxidant agent via inhibiting the nonenzymatic peroxidation which may increase the immunity of animals and improve their health and growth performance.(11) suggested that supplementation of N. sativa oil to ruminants ration acts as additional source of PUFA which are very important for animals health.
The objective of this work was to evaluate the effects of N. sativa oil additive as a natural growth enhancer of Egyptian Ossimi lambs.

Preparation of experimental rations
The basal total mixed ration (TMR) consisted of 40 % wheat straw, 25 % ground yellow corn, 20% soybean meal, 11 % wheat bran, 1.5% minerals and vitamins mixture, 0.8 % salts and 1.7 % limestone was used without additives as control ration (R1).While, two levels of Nigella sativa oil (extracted by coaled pressing using hydraulic press system) being 0.1 and 0.2% of DM were hand mixed with other feed ingredients for R2 and R3 groups, respectively.

Feeding trial
Eighteen growing Ossimi lambs aged 6-7 months old with 29.04 kg average body weight were divided by weight into three equal groups (6animals each) in a feeding trial lasted 90 days.Animals of all groups were fed individually on experimental rations offered at 4% of live body weight.Daily amounts of TMR were biweekly adjusted according to body weight changes.Feed intake was daily recorded, and refusals (if any) were daily collected and weighed.Clean drinking water was freely available at all times.

Digestibility trials
At the end of the feeding experiment three digestibility trials were carried out on three random sheep from each group over a period of 14 days, where 7 days were for adaptation and the other seven days for quantitative collection of feces and urine.Daily amounts of feed intake, feces and urine out-put were measured and daily recorded during the collection period.Dried samples of feces and feeds were ground to pass through 1-mm sieve, and stored in emeried bottles for chemical analysis.Samples of acidified urine were kept in clean dry glass bottles until nitrogen determination.Ruminal fluid samples were collected at the end of the experiment via a rubber stomach tube before feeding then at 3 and 6 hrs.after feeding.Samples of rumen content, for each animal, were filtered through four layers of cheesecloth, and then ruminal pH was immediately recorded using digital pH meter, then samples were stored at -20 C for latter ammonia and volatile fatty acids determination.

Chemical analysis
Chemical composition of experimental rations and feces were determined for dry matter (DM), crude protein (CP), crude fiber (CF), ether extract (EE) and ash according to the standard methods of (12).Nitrogen free extract (NFE) was calculated by difference.Urinary nitrogen (UN) was determined by the micro-kjeldahl method.Ruminal ammonia nitrogen (NH 3 -N) concentration was determined applying the micro diffusion method (13) and ruminal total volatile fatty acids (TVFA's) concentrations was determined according to (14).

Statistical analysis
Collected data concerning body weight gain, feed efficiency, nutrients digestibility and dietary nitrogen utilization were subjected to one-way analysis of variance according to (15) applying the general linear model procedure of (16).While, data of the rumen parameter was subjected to two-way analysis by the same previous procedure.Significant differences between means were tested at (P<0.05) using (17).

Results and discussion
Data of dietary chemical composition given in Table (1) indicate that the theoretically calculated nutritive value of the experimental TMR was nearly 70% as total digestible nutrients (TDN) and 12% as digestible crude protein (DCP) units.These values are sufficient to cover the nutritional requirements needed for growing local breeds of sheep when the experimental diet is fed at 4% DM of body weight as recommended by the (18).Mean daily feed intake; average daily gain and feed efficiency are presented in Table (2).It seems that feed intake did not influenced by N. sativa supplementation, however the slight insignificant increase of feed consumption for N. sativa groups than control is regarded to body weight fluctuation among groups, since animals were fed on restricted amounts being 3% of body weight, was observed.Final body weight and average daily body weight gain were higher by 4.72 and 13.9 % for R2 and 7.1 and 20 % for R3 compared with R1.Feed utilization efficiency was significantly (P<0.05)improved with supplemented diets (6.64, R1, vs. 6.19,R2, and 5.96, R3).Meanwhile, (19) stated that dietary supplementation with cinnamaldehyde increased DMI of feedlot cattle in the early weeks of the fattening period.The present results concerning effect of essential oils supplementation on improving weight gain and feed utilization efficiency were in agreement with the findings of .The development of body weight with advancing feeding period shown in Fig. (1), illustrate that animals of the control were better than other groups up to the sixth week of the feeding period, while animals fed N. sativa diets showed better weight gain than control afterwards till the end of the experimental feeding period, and the best result was attained with R3 (0.2%N.sativadiet).In other words, we can state that the beneficial effect of N. sativa oil on weight gain of sheep might need six weeks more or less, depends on; supplementation level, previous feeding status, feed allowances, type and age of animals and the environmental conditions.Data of nutrients digestibility and nutritive value of the experimental rations presented in Table (3) show that there were a significant (P<0.05)increases in the digestibility of DM, OM, CP and NFE of R2 and R3 (73.04, 78.79, 75.57and 85.86) and (76.62, 80.20, 78.32 and 86.29), respectively compared to 64.77, 71.84, 73.96 and 76.60% in the same order for R1.Nutritive values had the same trend as digestibility values, where, TDN and DCP% were significantly (P<0.05)higher for R2 and R3 than those of R1 and the highest values were recorded for R3.This improvement in nutrients digestion with R2 and R3 might be due to the stimulatory effect of essential oil (EO) on digestion process in the rumen.This result is in agreement with the findings of (21) who found that supplementation with 50 mg black seed oil in in-vitro trial tended to increase in vitro DM and organic matter disappearance compared with control, In the contrast, (22) found that addition of EO had no significant effect on total tract digestibility of dry matter, organic matter, crude protein and crude fiber.Such variation in results among researches might be due to that the response to EO in ruminants varies with the species, type and dose of EO, diet composition and whether the effect was investigated by in vivo or in vitro application (23)(24).
Dietary nitrogen balance and utilization values shown in Table (4) indicated that, there was a significant (P<0.05)increase in nitrogen balance (g/h/d) for sheep fed either R2 or R3 compared with those fed R1 being, 9.89 (R2) and 14.19 (R3) vs. 7.9 for control.Apparent dietary nitrogen utilization calculated as N-balance relative to N-intake or digestible-N showed similar significant trend for N. sativa oil supplemented diets in comparison with control.It's interesting to note that the urinary N loss was highly decreased with increasing the level of supplementation.In some previous studies on rabbits, it was mentioned similar results of lower N excretion with Moringa oleifera dry leaves (25) and with S. cerevisae and B. subtilis (26).It seems that the natural-bio additives are not only improving nutrients digestibility particularly protein but also improving nutrients absorption and utilization post digestion.The histograms of measured rumen fermentation parameters (pH, NH 3 -N and TVFAs) given in Figs. 2, 3  and 4 illustrate that all parameters recorded the highest values after 3hrs.offeeding with noticeable lower ammonia-N and higher TVFAs concentrations for animals fed N. sativa oil diets.Data in Table (5) indicate that, there was a significant (P<0.05)decrease in the overall mean of ruminal ammonia by 11.9 and 22.9% but there was a significant (P<0.05)increase in the rumen volatile fatty acids by 12.4 and 15.1%, respectively for R2 and R3 compared with R1.These results are in agreement with (21) who reported that NH 3 -N concentration decreased and VFA conc.increased in the ruminal fluid samples with black seed oil supplementation.According to some earlier studies, it was concluded that the addition of bio-active substances are influencing ruminal ammonia and TVFAs (6,7,27), with no significant effect on pH (28)(29)(30)(31).From the previous results it could be concluded that addition of Nigella sativa oil at 0.2% of DM in diets of sheep is recommended to improve feed utilization and growth performance of growing Ossimi sheep.
20 a,b,c Means have different superscripts in the same row are significantly different at (P<0.05).

Fig. 1 :
Fig. 1: Development of body weight for lambs fed experimental rations.
20 a 43.62 b 37.33 c of digestible N a,b,c Means have different superscripts in the same row are significantly different at (P<0.05).

Table 1 :
Chemical composition of experimental rations

Table 2 :
Feed intake, average daily body weight gain and feed efficiency of sheep fed experimental rations

Table 3 :
Nutrients digestibility and nutritive value of experimental rations Means have different superscripts in the same row are significantly different at (P<0.05).

Table 4 :
Effect of feeding experimental rations on nitrogen utilization of sheep