Growth performance and conjugated linoleic acid (CLA) content on meat of growing lambs fed diets containing vegetable oils.
Conjugated linoleic acid (CLA) as one of these components has numerous potential benefits for human health, including effective cancer fighting properties [1 and 2]. This is especially interesting considering that most of natural anti-carcinogens are of plant origin.
Nutritional quality has an important consideration in food choices because of the growing consumer awareness of the link between diet and health . The goal of increasing the efficiency of animal production is an important consideration in producing animal-derived food products. There is also increasing recognition that foods can be contributing factors in the prevention and development of some disease conditions. Many foods contain micro components that have many effects beyond those associated with their traditional nutrient content, and these are often referred to as "functional food" components .
The Food and Drug Administration (FDA) in July 2008 issued no objection letter on the generally recognition of CLA as safe for certain food categories and hence food companies are able to add CLA to products of certain food categories.
Meat and milk from grass-fed animals can produce 300-500% more CLA than those of cattle fed the usual diet of 50% hay and silage and 50% grain . The present work aimed to investigate the effect of adding flaxseed or sunflower oils to growing sheep diets on conjugated linoleic acid content in meat.
MATERIAL AND METHODS
The present work was carried out at the research facilities of the National Research Centre (NRC), Cairo, Egypt. Experimental animals were confined at the Sheep and Goat Research Unit at Nubaria Agricultural Experimental Station. Chemical analyses and carcass characteristics were adopted at the Laboratories of Animal Production Department, National Research Centre.
Three diets were tested. Control diet was formulated from 70% concentrate feed mixture and 30% clover hay, and meet the nutrient requirements of growing lambs proposed by NRC (1985). The concentrate feed mixture consisted of corn grains 60%, wheat bran 10%, cottonseed meal decorticated 15%, linseed meal 11%, molasses 2%, di-calcium phosphate 1%, salt 1%. The Chemical composition of feed mixture and clover hay is presented in Table 1.
Two vegetable oils: flaxseed oil (FSO) and sunflower oil (SFO) were added to the tested diets at level of 3% to formulate tested diets number 2 and 3.
Thirty six male Barki lambs aging about 6 months with average weight of 36 kg were used in this experiment. Lambs were randomly divided into three experimental groups, 12 lambs each. Average initial live body weights of animals were 36.75kg, 36.25Kg, and 36.83 Kg for CON, FSO and SFO groups, respectively. Each group was randomly fed the experimental diets as follows:
CON: Concentrat feed mixture CFM (70%) + clover hay (30%) without oil (control). FSO: control + 3% flaxseed oil. SFO: control + 3% sunflower oil.
Oils were mixed with the diets daily before feeding immediately. Animals were weighed weekly before feeding at 8:00 a.m. to calculate the average daily gain (ADG).
The growth trial lasted for 16 weeks. Lambs were fed at levels of 3.5 % DM of body weight.
Representative samples of experimental feed were analyzed for their nutrient contents according to A.O.A.C. (6) methods. Nitrogen free extract was calculated by difference. Chemical composition of feed ingredients and tested diets is presented in Table 2. Animals were fed in groups once a day at 8:00 a.m. Fresh water was available all the time. Feed intake and body weight of the lambs were weekly recorded during the experimental period.
Six animals from each group were slaughtered at the end of the experiment to study the effects of supplementing vegetable oils on meat quality of sheep fed diets containing sunflower oil and flaxseed oil. Animals were fasted for 12 hours before slaughter, which was performed according to the Islamic rules. The longissimus dorsi muscles of 9th, 10th and 11th ribs (best ribs cut) were wrapped and kept frozen (-20C) in polyethylene bags for chemical analyses.
Fatty acids composition:
Fatty acids profile of meet was determined by using gas liquid chromatography (GLC) according to Farag et al. .
Data were statistically analyzed according to . The differences among groups were estimated using the general linear model (GLM) procedures following the next model:
[Y.sub.ij] = [mu] + [Z.sub.1] + [E.sub.ij]
Where [mu] = general mean [Z.sub.i] = effect of treatment
[E.sub.ij] = experimental error.
Significance was tested at (P < 0.05) for all means separation.
RESULTS AND DISCUSSION
The two vegetable oils were analyzed for their fatty acid composition. The analyses of fatty acids are presented in Table 3.
The effect of adding two sources of vegetable oils to the diet of growing sheep on growth trails is shown in Table 4. Average daily gain (ADG), final body weight (FBW) and total body gain were higher by 17%, 6% and 17%, respectively, for the group feed FSO while these values were lower by 8.4%, 3.4% and 8.4% for the group fed SFO, respectively. Total digestible nutrients (TDN) and digestible crude protein (DCP) were higher (6.27%, 0.7%) and (3.24%, 4.28%), respectively, for the groups feed FSO and SFO, respectively.
The final body weight of the group fed the diet supplemented with FSO showed significant (p<0.05) increase (6%) compared with that fed SFO diets.
A significant (p<0.05) change in average daily gain (ADG) among treatments was observed. The highest average daily gain was recorded for lambs fed FSO, while the lowest average daily gain was recorded with lambs fed SFO and CON with no significant (p<0.05) differences between the two groups.
The dry matter intake (g/h/d and g/[w.sup.0.75]) showed no significant (p<0.05) differences among the three groups fed the experimental diets.
The DM, TDN, and DCP intake for each kilogram metabolic body size was not significantly different (p<0.05) among all diets. The similar DMI of lambs fed diets containing oils compared to those receiving the CON treatment agrees with the findings of many researchers who reported that supply of oils, when compared to diets without oil did not affect the DMI [9 and 10].
Feed conversion ratio according to dry matter intake (DMI) was lower by 2.5% for the group fed FSO while these value were higher by 1.5% for the group fed SFO
Feed conversion ratio as TDN and DCP were higher by 3.5%, 0.6%, respectively, for the groups fed FSO and 2.2%, 5.8%, respectively, for the groups fed SFO
Concerning feed conversion ratio, lambs fed FSO recorded the better value, than the groups fed the CON and SFO.
The results of this particular work on growing Barki lambs showed that adding vegetables oils (VO) treatment of diet for lambs had no effect on any of the growth performance parameters these results are in agreement with those found by Ferreira et al. , Alberti et al.  and Roy et al. .
Fatty acid composition of muscle:
The main effects of dietary treatments on lamps meat fatty acids are present in Table 5.
Meat of FSO group was significantly high of their content of polyunsaturated fatty acids (PUFA) compare to the other groups. Total PUFA concentration was raised by 26.65% and 24.52% in meat of FSO and SFO groups compared to control, respectively (Fig. 1).
Monounsaturated fatty acids (MUFA) content in meat of FSO was significantly higher than SFO groups by 10%. A FSO, FSO and SFO groups were significantly high of their content of MUFA in meat by 37% and 30%compared to control, respectively.
While SFA was significantly lower in meat of animal fed on diet supplemented with FSO.
The amount of CLA (c18:2 trans 10, cis 12) was significantly increased about 86% (8-fold) and 83%(6-fold) in meat of lambs consumed FSO and/or SFO diet compared to control group, respectively, as shown in Figure (2). 9,12,15-Octadecatrienoic (ra3) was created in meat of lambs consumed FSO and/or SFO diet with concentration 1.10 and 1.14, respectively.
The decrease in the 9-Octadecenoic acid (Z) concentration was responsible for the reduction in the concentration of the monounsaturated fatty acids in the meat (Table 5). Indeed, a decreased concentration of 9-Octadecenoic acid (Z) (C18:1 cis-9) in the meat of sheep supplemented with linoleic acid-rich oils has often been reported [14; 15; 16]. The intake of 9-Octadecenoic acid (Z) was higher in animals fed the diets with added oils. Therefore, the lower level of 9-Octadecenoic acid (Z) observed for the treatments with supplemental fatty acids could be attributed to the lower transfer of this fatty acid from blood to muscle and/or a decrease in its synthesis from Octadecanoic acid by the stearoyl-CoA desaturase. In addition, Sessler et al.  demonstrated that linoleic and linolenic acids exert an inhibitory effect on the expression of this enzyme. In the present experiment, the supply of linoleic and linolenic acids was largely increased for all treatments with supplemental fatty acids (Table 3). The observed increase in the concentration of 11- Octadecenoic acid and C18:2 trans-10, cis-12 CLA in the meat of the lambs supplemented with fatty acids (Table 5) probably resulted from the higher synthesis of this fatty acid in the rumen. 11-Octadecenoic acid and C18:2 trans- 10, cis-12 CLA are synthesized in the rumen as a transient intermediate in the process of biohydrogenation of linoleic acid . Because C18:2 trans-10, cis-12 CLA can be synthesized from 11-Octadecenoic acid through, the stearoyl-CoA desaturase activity [19 and 20], endogenous synthesis may also have contributed to the increase in the concentration of C18:2 trans-10, cis-12 CLA in the meat of the lambs supplemented with fatty acids.
The linear decrease in the Octadecanoic acid concentration in meat according to oils supply demonstrates that small amounts of DHA present in diets with flaxseed and sunflower oils (Table 2) were effective in reducing ruminal biohydrogenation of 11-Octadecenoic acid to Octadecanoic acid. Because the concentration of 11-Octadecenoic acid increased linearly with the addition of oils, a similar increase was expected in the concentration of CLA C18:2 trans-10, cis-12.
This result support the idea that the activity of the stearoyl-CoA desaturase. Enzyme was negatively affected by the supplemental fatty acids , but a FSO allows an exploration of the hypothesis that the flow of vaccenic acid exceeded the desaturation capacity of stearoyl-CoA desaturase in muscle tissue .
Using flaxseed or sunflower oils, in growing lambs diets is recommended, because it improves the lipid profile of the meat by increasing the concentration of CLA and omega 3. Additionally, supplementing 3% of flaxseed or sunflower oils had no negative effect on the feed intake, ADG, and feed efficiency of the lambs fed experimental diet.
Received 5 August 2015
Accepted 28 August 2015
Available online 15 September 2015
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(1) Eman H. El-Sabaawy, (1) Sawsan M. Gad, (2) T.M. El-Bedawy, (1) H.M. Ali and (2) A.M. Abd El-Gawad
(1) Department of Animal Production, National Research Centre, 33 el-bohouth street, Dokki, Giza, Egypt, 12622.
(2) Department of Animal Production, Faculty of Agriculture Cairo University Giza, Egypt.
Corresponding Author: Eman H. El-Sabaawy, Department of Animal Production, National Research Centre, 33 el-bohouth street, Dokki, Giza, Egypt, 12622.
Table 1: Chemical composition of feed mixture and barseem hay (on DM basis). Chemical composition, % Ingredients Ash NFE EE CP CF OM DM 13.10 51.61 4.33 16.03 14.93 86.90 92.24 CFM * 16.01 39.71 2.54 10.31 31.43 83.99 91.68 Clover hay * CFM: Concentrate feed mixture. Table 2: Chemical composition of tested diets (on DM basis). Chemical composition, % diet Ash NFE EE CP CF OM DM 13.98 48.04 3.79 14.31 19.88 86.02 92.07 CON 13.98 45.24 6.59 14.31 19.88 86.02 92.07 FSO 13.98 45.24 6.59 14.31 19.88 86.02 92.07 SFO CFM: Concentrate feed mixture, CON: CFM + clover hay (control), FSO: control + flaxseed oil (3%), SFO: control + sunflower oil (3%). Table 3: Fatty acid composition of flaxseed oil (FSO) and sunflower oil (SFO). SFO FSO Fatty acids mg/gm oil 0.18 0.13 C14:0 0.05 0.03 C15:0 6.49 6.69 C16:0 0.23 0.07 C16:1 3.81 3.59 C18:0 23.14 17.90 C18:1 65.27 18.33 C18:2 0.40 52.69 C18:3 0.21 0.28 C20:0 0.19 0.23 C20:1 0.01 0.06 C20:6 10.74 10.72 SFA 23.56 18.20 MUFA 65.70 71.08 PUFA SFA: saturated fatty acids, MUFA: mono unsaturated fatty acids, PUFA: poly unsaturated fatty acids Table 4: Daily gain, nutrients intake and feed conversion ratio of Barki lambs consumed different tested diets. Item CON FSO SFO Initial body wt. (IBW), kg 36.75 36.25 36.83 Final body wt. (FBW), kg 63.13 (ab) 67.08 (a) 61.00 (b) Total body gain, kg 26.38 (b) 30.83 (a) 24.17 (b) Average daily gain (ADG), g 214 (b) 251 (a) 196 (b) Metabolic body size (Bw 0.75) 18.76 19.25 18.49 Dry matter intake, g/head/day 1384 1384 1384 Total digestible nutrients 66.72 (c) 70.90 (a) 67.18 (b) Digestible crude protein 12.19 (c) 12.58 (b) 12.71 (a) Intake, g/ Kg w 0.75/day Dry matter 73.76 71.88 74.87 Total digestible nutrients 3.56 3.68 3.63 Digestible crude protein 0.65 0.65 0.69 Feed conversion ratio (FCR), kg nutrient intake /kg gain Dry matter 6.47 (a) 5.51 (b) 7.06 (a) Total digestible nutrients 0.31 0.28 0.34 Digestible crude protein 0.06 0.05 0.06 (a,b) Means in the same row within each treatment having different super scripts differ (P<0.05). CFM: Concentrate feed mixture, CON: CFM + clover hay (control), FSO: control + flaxseed oil (3%), SFO: control + sunflower oil (3%). Table 5: Fatty acids concentration of Barki lambs feed tested diets. (%of total fatty acids). Items CON FSO SFO Pentadecanoic acid 1.86 (a) 1.13 (b) 1.80 (a) 9-Hexadecenoic acid 1.04 (b) 1.34 (a) 1.28 (a) Hexadecanoic acid 3.84 (b) 2.60 (a) 3.08 (a) Heptadecanoic acid 6.09 (a) 4.36 (b) 5.60 (a) cis-10-Heptadecenoic acid 2.27 (c) 3.55 (a) 3.04 (b) Octadecanoic acid 65.40 (a) 58.32 (b) 58.64 (b) 9-Octadecenoic acid (E) 5.47 (a) 0.00 (b) 0.00 (b) 9-Octadecenoic acid (Z) 0.00 (b) 6.49 (a) 6.36 (a) cis-13-Octadecenoic acid 0.00 (c) 2.69 (a) 2.00 (b) 9,12-Octadecadienoic acid (Z,Z) 13.75 (c) 16.26 (a) 15.40 (b) 9,12,15-Octadecatrienoic acid ZZZ 0.00 (b) 1.10 (a) 1.14 (a) Methyl 10-trans,12-cis- 0.28 (c) 2.16 (a) T65 (b) Octadecatrienoic octadecadienoate SFA 77.19 (a) 66.41 (c) 69.13 (b) MUFA 8.78 (c) 14.07 (a) 12.68 (b) PUFA 14.03 (c) 19.52 (a) 18.19 (b) (a,b) ...: Means in the same row within each treatment having different super scripts differ (P<0.05). CFM: Concentrate feed mixture, CON: CFM + clover hay (control) , FSO: control + flaxseed oil (3%), SFO: control + sunflower oil (3%).
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|Author:||Sabaawy, Eman H. El-; Gad, Sawsan M.; Bedawy, T.M. El-; Ali, H.M.; Gawad, A.M. Abd El-|
|Publication:||Advances in Environmental Biology|
|Date:||Aug 1, 2015|
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