سلماز خلیلی سامانی

 It has been estimated that feed is the major cost associated with commercial poultry production. Conventional plant proteins, such as soybean meal tend to increase the poultry production costs due to limitation in cultivation in some region and therefore, their being transported from other countries. Hence, inclusion of non-conventional feed resource becomes of primary importance in poultry production to maintain the productivity at a lower cost. Black seed (Nigella sativa) referred to an important medical crop in many countries and is primarily consumed as medical oil. Black seed meal (BSM) is by-product after oil removal and can be used as a protein-rich meal (21). Black seed meal contains about 31.75 % crude protein and 19.37 % ether extract and it can be used as good sources of protein and energy (21) and substitution of soybean meal in laying hens practical diets. However, reports on the use of BSM in laying hens diets in second cycle of production are not enough, therefore, in this study, we considered the effect of different levels of black seed meal on laying hens performance in second production cycle.

Materials and Methods :

This experiment was conducted to determine the fatty acids composition of black seed meal and its effects on performance and egg qualitative traits of laying hens in second production cycle. In the first step, Gas-chromatography was used for determination the fatty acids composition of BSM. In the second step, a total of One hundred and twenty Hy-Line W-36 leghorn hens were housed in cages and randomly allocated to 5 treatment groups for 8 weeks. Each group was divided in to 4 replicates. Feed and water were provided ad libitum. The hens received basal diet (corn and soybean meal based diet with 14.80 % crude protein and 2813 kcal/ kg metabolizable energy) that was formulated to meet the Hy-line W-36 requirements recommended for nutrients. The diet did not have any antibiotics and coccidiostats. Dietary treatments were included 0, 5, 10, 15, and 20 percentage of BSM by expense of Soybean meal in basal diet and clarified as BSM0 (control), BSM5, BSM10, BSM15 and BSM20 respectively. Experiment was designed in a completely randomized design. Egg weight (gr), egg production (%) and egg mass (gr/hen/day) were recorded daily. Feed consumption was measured weekly and feed conversion ratio (FCR) (grams of feed: grams of egg mass) was calculated weekly too. At the end of 2, 4, 6 and 8 weeks of the experiment, two eggs from each replicate were randomly selected for measurement the egg qualitative traits. In this paper laying hens performance factors and egg quality parameters were calculated in three phase, the first 4 weeks, second 4 weeks and total period. Blood serum characteristics were evaluated in the end of experiment by bleeding from laying hens wings.

Results and Discussion:

 The results of this experiment showed that linoleic acid (41.51), oleic acid (34.67 %), palmetic acid (16.12 %), stearic acid (5.59), and linolenic acid (1.97) were the major BSM fatty acids. As it clear, the linoleic acid and oleic acid are most abundant fatty acid (unsaturated) in BSM. Feed intake was decreased by inclusion of BSM in laying hens diet and minimum feed intake was observed in BSM20. It seems to be the bitter taste of black seed meal is responsible for the decline of feed intake. It was reported that BSM has anti-nutritional substance and alkaloids (saponins), that these factors can reduce feed intake when used in high amount in poultry diets (21 and El-Dakhakhny, 1996). Laying hens egg mass was decreased in BSM10, BSM15 and BSM20 groups when compared with control group. Egg mass was calculated by multiplying egg weight in egg production. Reduced of feed intake can affect availability of nutrient for egg production and egg weight, and, therefore, egg mass will be decrease. Scientists reported that BSM can increase laying hens’ body weight and increasing body weight can decrease egg production. Laying hens’ serum cholesterol and triglyceride content were decreased significantly in BSM5 when compared with other groups. It was reported that essential oils in BSM can reduce activity of HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase that has vital role in cholesterol synthesis (Crowell, 1999).

Conclusion :

According to the results of this experiment, using BSM in 5 percent can reduce blood cholesterol and triglyceride without adverse effect on performance parameters.