This study investigated the effects of supplementary dietary lipid sources on the fatty acid profile and lipid oxidation of eggs. Five isoenergetic (12.6 MJ AME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated, using a control diet (50 : 50 blend of fish-and linseed oil), fish oil, sunflower oil, high oleic acid (HO) sunflower oil and tallow at a 30 g/kg inclusion level. Two hundred individually caged HyLine Silver-Brown hens (20 weeks of age) were randomly allocated to the five dietary treatments (n = 40 hens/treatment). Birds received the experimental diets from 20 weeks of age. At 30 weeks of age, 12 eggs per treatment were randomly selected for analyses of egg yolk fatty acid methyl esters (FAME), thiobarbituric acid reactive substances (TBARS) and peroxide values (PV). Dietary lipid sources affected FAME, TBARS and PV of egg yolk significantly. The fish oil treatment resulted in the highest TBARS (0.27 mg malonaldehyde/kg yolk) and PV (3.96 milli-equivalent peroxide/kg fat) whereas the HO sunflower oil resulted in the lowest TBARS (0.13 mg malonaldehyde/kg yolk) and PV (2.77 milli-equivalent peroxide/kg fat). Fish oil also resulted in the lowest n-6 to n-3 ratio (1.16 to 1), while sunflower oil resulted in the highest ratio (24.6 to 1). Results indicate that the fatty acid profile of eggs could be altered by means of dietary intervention. However, an improvement of omega-3 type fatty acids of eggs will result in a higher susceptibility to lipid oxidation and possibly a shorter shelf-life of stored eggs. ________________________________________________________________________________

________________________________________________________________________________ AbstractA study was conducted to determine the influence of different particle size limestone in layer diets on egg production and eggshell quality during the later stages of egg production (>54 weeks of age). Calcitic limestone (360 g Ca/kg), consisting of small (<1.0 mm), medium (1.0 -2.0 mm) and large (2.0 -3.8 mm) particles were obtained from a specific South African source that is extensively used in poultry diets Isoenergetic (14.32 MJ AME/kg DM) and isonitrogenous (172.01 g CP/kg DM) diets with a dietary Ca content of 39.95 g Ca/kg DM were used. Sixty nine, individual caged Lohmann-Silver pullets, 17 weeks of age, were randomly allocated to the three treatments (n = 23) for the determination of various egg production and eggshell quality characteristics. Egg production and eggshell quality data recorded on individual basis at 54, 58, 64 and 70 weeks of age were pooled to calculate and statistical analysed parameter means for the late production period. Different limestone particle sizes had no effect on any of the tested egg production and eggshell quality parameters. These results suggested that larger particles limestone are not necessarily essential to provide sufficient Ca 2+ to laying hens for egg production and eggshell quality at end-of-lay, provided that the dietary Ca content satisfies the requirements of the laying hen.________________________________________________________________________________

________________________________________________________________________________ AbstractThe objective of this study was to investigate the effects of different dietary lipid sources and inclusion levels on lipid oxidation of thigh and breast muscle of male broilers. Eight isoenergetic (15.12 MJ AME/kg DM) and isonitrogenous (222.8 CP/kg DM) diets were formulated, using sunflower oil (SO), high oleic sunflower oil (HOSO), fish oil (FO) and tallow (T) at 30 g/kg and 60 g/kg inclusion levels. Eight hundred, day-old Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and further subdivided into four replicates/treatment (n = 25). All birds received a standard diet for 14 days whereafter the experimental diets were fed for an additional 28 days until termination of the study. Birds were slaughtered under commercial abattoir conditions at 42 days of age. Carcasses from 12 birds per treatment (n = 12) were trimmed for breast and thigh cuts by removing the skin. Twelve breast and thigh samples from each treatment group were stored at 4 °C for seven days under an oxygen permeable overwrap film and another 12 breast and thigh samples were vacuum packed and stored at -18 °C for 100 days. Meat samples were used for thiobarbituric acid reactive substances (TBARS) analysis. Birds fed FO showed significantly more oxidation in both thigh and breast meat than birds from any of the other treatments during storage. These results indicated that dietary lipid sources do influence the lipid oxidation processes of broiler meat. ________________________________________________________________________________

________________________________________________________________________________ AbstractA study was conducted to determine the influence of different dietary lipid sources and inclusion levels on production performance of male broilers. Eight isoenergetic (15.1 MJ AME/kg DM) and isonitrogenous (223 g CP/kg DM) diets were formulated, using high oleic sunflower oil (HO), sunflower oil (SO), fish oil (FO) and tallow (T) at a 30 g/kg and 60 g/kg dietary inclusion level. Eight hundred (800), dayold Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and were further subdivided into four replicates/treatment (n = 25). All birds receive a standard commercial diet for the first 14 days, where-after the experimental diets were fed for 28 days. Feed intake and body weights were recorded weekly, while mortalities were recorded and dead birds weighed daily. Mortalities were brought into consideration during the calculation of average daily feed intake (g feed/bird/day) and feed conversion ratio (g feed/g body weight gain). Contrary to saturated fatty acids (T), the inclusion of unsaturated fatty acids (HO, SO, FO) at a higher level (60 g/kg) resulted in a significantly improved FCR. It seems that the optimum dietary inclusion level of saturated fatty acids is lower (30 g/kg) than that of unsaturated sources.________________________________________________________________________________

________________________________________________________________________________ AbstractThis study was conducted to investigate the effects of dietary fatty acid saturation on production performances of laying hens at end-of-lay. Five isoenergetic (12.6 MJ AME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated using different lipid sources at a constant 30 g/kg inclusion level. The control diet was formulated using a blend (50 : 50) of linseed-and fish oil, while the other treatments consist of pure fish oil (polyunsaturated n-3), sunflower oil (polyunsaturated n-6), high oleic acid (HO) sunflower oil (monounsaturated n-9) and tallow (SFA). Two hundred, individually caged Hy-Line SilverBrown laying hens (20 weeks of age) were randomly allocated to the five dietary treatments (n = 40 replicates/treatment) and received the experimental diets for 54 weeks from 20 to 74 weeks of age. During weeks 58, 62, 66, 70 and 74 of age (end-of-lay period), all eggs produced were recorded and individually weighed while feed intake, as well as body weights of birds, were determined. Data for the respective collection weeks were pooled to calculate and statistical analyse production parameter means for the end-oflay period. Average daily feed intake of birds in the polyunsaturated n-3 treatment (97.5 g/b/d) were the lowest while that of the polyunsaturated n-6 treatment (102.4 g/b/d) the highest. Furthermore, despite the significant effect of fatty acid saturation on feed intake, it had no effect on hen-day egg production, egg weight, egg output, feed efficiency or body weight of hens during end-of-lay. Since results of the current study fail to indicate a clear trend regarding dietary fatty acid saturation on feed intake of birds, it could be concluded that the long term exposure to a range of fatty acid saturation levels, has no negative effect on hen performance.

________________________________________________________________________________ AbstractA study was conducted to determine the influence of different dietary lipid sources and inclusion levels on sensory characteristics of chicken breast meat. Eight isoenergetic (15.1 MJ AME/kg DM) and isonitrogenous (223 g CP/kg DM) diets were formulated, using high oleic sunflower oil (HOSO), sunflower oil (SO), fish oil (FO) and tallow (T) at 30 g/kg and 60 g/kg inclusion levels. Eight hundred, day-old Ross 788 broiler males were randomly allocated to the eight treatments (n = 100) and further subdivided into four replicates/treatment (n = 25). All birds receive a commercial starter diet for the first 14 days, where-after the experimental diets were fed for 28 days. At 42 days of age, three birds/replicate (n = 12/treatment) were randomly selected, weighed and slaughtered at a commercial abattoir. Breast muscles were removed from the chilled carcasses (4 °C) and de-skinned. Meat samples were wrapped in aluminium foil and steamed (200 °C) before cutting into smaller pieces (2.5 cm 3 ) and served to the respondents (n = 75) of a consumer panel. Each respondent tasted eight meat samples while completing a nine-point hedonic scale questionnaire. Meat samples of the HOSO treatment were preferred, while FO samples were the least acceptable to the respondents. These results suggested that dietary lipid sources could be used to manipulate sensory characteristics of broiler breast meat according to consumer preferences. ________________________________________________________________________________

________________________________________________________________________________ AbstractA study was conducted to investigate the effect of dietary lipid saturation on nutrient digestibility of layer diets. Five isoenergetic (12.6 MJ AME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated using different lipid sources at a constant 30 g/kg inclusion level. The control n-3 diet was formulated using a blend (50 : 50) of linseed-and fish oil, while fish oil (polyunsaturated n-3), sunflower oil (polyunsaturated n-6), high oleic acid (HO) sunflower oil (monounsaturated n-9) and tallow (saturated fatty acid) were used as other supplementary lipid sources. The five dietary treatments were randomly allocated to the two hundred (200) individually caged Hy-Line Silver-Brown laying hens (20 weeks of age) (n = 40/treatment). Experimental diets were provided to the birds on an ad libitum basis for a 22 week period (from 20 to 42 weeks of age). At 42 weeks of age, six hens per treatment (n = 6 replicates/treatment), were randomly selected to partake in a digestibility study over a 7 day period using the total collection technique. The polyunsaturated n-6 treatment resulted in the lowest crude protein digestibility, whereas the saturated fatty acid treatment resulted in the lowest fat digestibility. Furthermore, the polyunsaturated n-3 diet resulted in the highest dietary AME (13.29 MJ/kg DM) and AME n (12.74 MJ/kg DM) content. ________________________________________________________________________________

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