Effect of vitamin E on reproductive performance of heavy broiler breeder hens

2013 Poultry Science Association, Inc. Effect of vitamin E on reproductive performance of heavy broiler breeder hens M. Zaghari, 1 V. Sedaghat, and M. Shivazad Department of Animal Science, University of Tehran, Karaj, Iran 31587-77871 Primary Audience: Nutritionists, Veterinarians, Broiler Breeder Managers, Flock Supervisors SUMMARY The effect of dietary vitamin E as an antioxidant and -reducing agent was evaluated in an in vivo experiment. One hundred and eight commercial broiler breeder hens and 36 male breeders at the end of their production cycle (62 72 wk) were used as a bird sensitive to reproductive disorders related to obesity. The experimental design was a completely randomized design in a 3 3 factorial arrangement with 4 replicates and 3 hens in each. Factors included 3 levels of vitamin E (0, 200, and 400 mg/kg of α-tocopherol acetate added to the basal diet) and 3 groups of hens with differing BW (standard, heavy, and becoming heavy). Heavy and standard hens received a restricted amount of feed according to the strain requirement recommendations. Becoming heavy hens were fed 30% more than standard requirement. The egg production between standard, becoming heavy, and heavy groups were significantly different. The becoming heavy hen egg production was 3.1% lower than standard, and heavy hens produced 16.9% less than standard hens. Becoming heavy and heavy hens stored higher fat and in their livers and had more yolk and abdominal fat than standard BW hens (P < 0.05). An added 400 mg/kg of vitamin E resulted in significantly lower liver fat compared with 0 and 200 mg/kg of added vitamin E. The addition of 200 and 400 mg/kg of vitamin E to the broiler breeder hen diet reduced the fractional egg yolk weight and increased the number of white ovarian follicles significantly. Added vitamin E increased high-density lipoprotein linearly. Feeding vitamin E at levels 4 times above that recommended by the strain management guide decreased fractional yolk weight, blood triacylglycerol concentration, and changed the metabolic direction of in heavy broiler breeder hens. Key words: vitamin E, broiler breeder, heavy 2013 J. Appl. Poult. Res. 22 :808 813 http://dx.doi.org/10.3382/japr.2012-00718 DESCRIPTION OF PROBLEM Genetic selection for growth parameters in meat-type chickens gives rise to a parent stock (broiler breeders) that tends to lack the ability to self-regulate feed intake. As such, their high body mass is associated with excessive fat deposition, reproductive disorders, and high mortality rates. Taherkhani et al. [1] reported that ad libitum broiler breeder hens had significantly lower egg production as well as higher BW, plasma triglycerides, and concentrations than their restricted fed counterparts. Chen et al. [2] reported that broiler breeder hens be- 1 Corresponding author: mzaghari@ut.ac.ir

Zaghari et al.: VITAMIN E AND REPRODUCTION 809 came heavy after 10 d of overfeeding, and high glucose availability due to hyperphagia could result in lipotoxicity and ovarian dysfunction. Lipotoxicity is associated with nonfunctional leptin signaling, excessive accumulation of triacylglycerol, and fatty acids in nonadipose tissues as well as altered circulating and tissue lipid profiles [2]. In studies on animals and humans, a beneficial role of vitamin E supplementation has been demonstrated in redistributing among the lipoproteins (from low- to high-density lipoprotein) as well as decreasing plasma total levels. In studies with rats, supplementation with various dietary levels of vitamin E decreased levels in serum and liver [3]. Sahin et al. [4] reported that vitamin E lowered the total serum concentration of laying hens. Blood changes are evaluated in some studies on humans and different animal species. However the studies on broiler breeder hens are limited. If the effect of antioxidants such as vitamin E on serum and yolk content is determined, we can reduce the negative effects of obesity of breeder hens on egg production rate and the egg. Therefore, the objective of the present study was to determine the effect of supplemental dietary vitamin E on the reproductive performance of standard, heavy, and becoming heavy broiler breeder hens. MATERIALS AND METHODS All experimental procedures used were approved by the Animal Welfare Committee of the Department of Animal Science, University of Tehran. General One hundred and eight commercial broiler breeder hens and 36 male breeders (Ross 308) at the end of their production cycle (62 72 wk) were used as a bird sensitive to reproductive disorders related to obesity. The experimental design was a completely randomized design in a 3 3 factorial arrangement with 4 replicates and 3 hens in each replicate. Factors included 3 levels of vitamin E (0, 200, and 400 mg/kg of α-tocopherol acetate added to the basal diet) and 3 groups of hens with different BW control schedules. The 3 BW groups were standard (S), heavy (H), and becoming heavy (BH). Hens were selected from a commercial breeder flock, weighed, and divided into 2 BW categories (heavy and standard). The initial BW range for S and BH were 4,300 to 4,400 g and for heavy hens was 4,700 to 4,800 g. Feed was distributed immediately at the beginning of the photoperiod, once a day, and hens were weighed daily before feed distribution. Heavy and S hens received a restricted amount of feed according to the strain (Ross 308) requirement recommendations [5]; BH hens were fed 30% more than the standard requirement. The basal diet contained 2,800 kcal of ME and 14.5% CP. The vitamin premix used for basal diet formulation was without any form of vitamin E. Dietary treatments were introduced after the 2-wk pre-experimental period to adjust egg production within groups and depletion of vitamin reserves. Male breeders received 140 to 145 g/d of a standard male diet (2,800 kcal of ME and 13% CP) separately and had a mating opportunity for 2 h each day. Experimental units were 1.25 2.5-m litter pens covered by 5 cm of wood shaving material. Each pen contained a separate male and female manual feeder trough and nest box. The photoperiod was 14.5:9.5 L:D per day. The source of light was an incandescent bulb lamp and the light intensity at floor level was 30 lx. Egg production, egg weight, and egg shell quality were recorded daily. Body weight and egg quality were recorded biweekly. Egg shell thickness was measured by ultrasonic basis device (Echometer 1062, Robotmation Co. Ltd., Tokyo, Japan). Yolk and liver were measured by improved procedure of Pasin et al. [6] every 14 d and at the end of experiment, respectively. Blood and carcass parameters were measured at the end of the experiment. Blood constituents were analyzed by a Hitachi 717 auto analyzer (Hitachi, Boehringer GmbH, Mannheim, Germany). Total blood antioxidant content was measured according to the procedure described by Benzie and Strain [7]. After removing hierarchical follicles, ovaries were weighed and follicles were classified into 3 groups: hierarchical follicles (large yellow follicles; >8 mm), small yellow follicles (2 8 mm), and white follicles (2 5 mm).

810 JAPR: Research Report Statistics Data were analyzed by the GLM procedure of SAS [8] appropriate for completely randomized 3 3 factorial design with 4 replicates and 3 hens in each. Treatments means were compared using Duncan s multiple range test (P < 0.07). RESULTS AND DISCUSSION The effect of treatments on performance and egg shell quality are presented in Table 1. Standard, BH, and H hens had 184, 374, and 163 g of BW gain over the 10 wk they received experimental diets. The ADFI of hens during the entire experimental period was significantly different (P < 0.05). The egg production between S, BH, and H groups were significantly different (P < 0.05). The BH hen egg production was 3.1% lower than S, and H hens performed 16.9% worse than S hens. Overfeeding broiler breeder hens had a negative effect on egg shell quality (P < 0.01); however, vitamin E had no beneficial effect on shell thickness and shell breaking strength. The effect of vitamin E supplementation on fractional egg yolk weight, from 62 to 72 wk of age, is shown in Figure 1. The addition of 200 and 400 mg/kg of α-tocopherol to the broiler breeder hen diet decreased the fractional egg yolk weight (P < 0.05). The effects of vitamin E and hen BW on ovarian morphology are shown in Table 2. The Figure 1. The effect of supplementation of vitamin E on fractional yolk weight (62 72 wk). Different letters (a,b) represent significant differences (P < 0.05). number of postovulatory follicles in H hens was less than other BW groups (P < 0.05). Supplemental vitamin E increased the number of white ovarian follicles significantly (P < 0.07). Mean measured liver parameters, yolk, and abdominal fat fractional weight are presented in Table 3. Hens with access to the 30% more feed (BH), had a heavier liver (P < 0.05) than their restricted counterparts (H). Interestingly, BH and H hens stored higher fat and in their livers (P < 0.05) and also had more yolk and abdominal fat than S hens (P < 0.05). An additional 400 mg/kg of vitamin E resulted in significantly (P < 0.05) lower liver fat compared with 0 and 200 mg/kg of added vitamin E. Table 1. Effect of vitamin E and BW on broiler breeder performance (62 72 weeks) 62-wk BW 2 72-wk BW 3 Feed intake (g/d) Egg production 4 (%) Egg weight 4 Eggshell thickness (mm) Eggshell breaking strength (kg/cm 2 ) S 4,363 b 4,547 b 146 b 49.8 a 69.4 0.287 a 2.181 a BH 4,389 b 4,763 a 161 a 46.7 a 70.2 0.263 b 1.826 b H 4,702 a 4,865 a 143 b 32.9 b 70.4 0.280 a 2.068 a 0 4,518 4,686 148 39.7 70.1 0.278 1.946 200 4,498 4,771 149 41.2 70.1 0.279 2.067 400 4,438 4,718 154 48.5 69.8 0.274 2.062 SEM 70.00 72.03 1.74 3.26 0.65 0.005 0.065 BW 0.0001 0.014 0.0001 0.002 0.5 0.013 0.002 0.40 0.706 0.06 0.14 0.91 0.76 0.34 a,b Means within a column without a common superscript differ significantly (P < 0.05). 2 Initial BW. 3 Final BW. 4 Values are the average of the 10-wk experimental period.

Zaghari et al.: VITAMIN E AND REPRODUCTION 811 Table 2. Effect of vitamin E and hen BW on ovarian morphology (62 72 wk) Ovary weight Oviduct weight Large yellow Small yellow White Postovulatory S 51.57 51.07 3.79 13.20 31.38 3.04 a BH 54.91 51.15 4.25 13.63 32.70 3.29 a H 48.26 40.42 3.63 13.75 30.38 1.71 b 0 53.85 52.76 4.17 13.71 28.5 b 2.38 200 51.16 42.79 3.63 12.55 29.4 b 2.55 400 49.74 47.11 3.88 14.34 36.5 a 3.13 SEM 5.76 4.05 0.47 1.42 2.58 0.45 BW 0.71 0.11 0.63 0.96 0.81 0.04 0.87 0.23 0.72 0.66 0.07 0.47 a,b Means within a column without a common superscript differ significantly (P < 0.05). Blood concentrations of hens on different treatments are shown in Table 4. Neither added vitamin E nor BW categories had a significant effect on blood concentration. Increased feed allocation (for BH hens), about 30% more than strain management guide recommendations, resulted in significantly (P < 0.05) increased blood triacylglycerol (TAG). Hens fed diets containing 400 mg/kg of vitamin E had a significantly (P < 0.05) lower blood TAG concentration than those that received 0 or 200 mg/ kg of added vitamin E. Hens fed a diet fortified with vitamin E had a higher blood antioxidant concentration than hens fed a basal diet (P < 0.01). Added vitamin E increased high-density lipoprotein linearly (P < 0.05). The interaction between BW and vitamin E added to the breeder hen diet on high-density lipoprotein also was significant (P < 0.01). Therefore, the highest blood level of high-density lipoprotein was observed in S hens that received 400 mg/kg of vitamin E. The interactions between experimental factors were not significant on any of the measured criteria (except those previously mentioned). Similar to previous reports [2, 9], overfeeding in our study resulted in hens that were 267 g heavier at 72 wk of age compared with restricted fed counterparts (BH and H vs. S hens). In the present study, increasing hen BW decreased egg production (Table 1) and the number of postovulatory follicles (Table 2) and increased liver weight, fat and content (Table 3), and blood TAG (Table 4). Conversely, added Table 3. Effect of vitamin E and hen BW on liver weight, liver and yolk content, and abdominal fat (62 72 wk) Liver weight Liver fractional weight Liver fat (g/100 g of DM) Liver (mg/g) Yolk (mg/g) Abdominal fat fractional weight S 75.71 b 1.72 ab 23.86 b 2.73 b 18.07 b 3.37 b BH 85.16 a 1.80 a 33.84 a 3.07 ab 18.17 b 4.09 a H 78.91 ab 1.58 b 31.20 a 3.47 a 20.12 a 4.51 a 0 78.19 1.68 29.67 ab 3.24 19.30 3.95 200 82.71 1.74 33.77 a 3.08 18.70 4.18 400 78.58 1.68 25.16 b 2.94 18.37 3.83 SEM 2.50 0.61 2.27 1.71 0.42 0.2 BW 0.038 0.04 0.014 0.019 0.002 0.001 0.40 0.67 0.041 0.46 0.27 0.47 a,b Means within a column without a common superscript differ significantly (P < 0.05).

812 JAPR: Research Report Table 4. Effect of vitamin E and hen BW on blood parameters of broiler breeder hens (62 72 wk) Cholesterol Triacylglycerol High-density lipoprotein Low-density lipoprotein Total antioxidant (nmol/mg of BSA) S 0 227.25 1,524.50 28.00 bc 44.00 165.20 S 200 203.50 1,384.50 32.50 bc 38.00 169.53 S 400 174.00 1,145.00 51.50 a 45.50 178.65 BH 0 201.25 1,937.00 31.00 bc 42.25 174.65 BH 200 244.50 1,867.50 26.50 bc 42.50 184.25 BH 400 187.00 1,724.00 40.50 abc 38.00 181.00 H 0 219.00 1,682.50 24.50 c 47.50 167.65 H 200 144.50 1,631.00 42.25 ab 47.00 175.65 H 400 193.00 1,434.25 27.00 bc 43.00 188.00 SEM 24.32 103.13 4.89 4.42 3.88 S 201.59 1,351.34 c 37.34 42.50 171.13 b BH 210.92 1,842.84 a 32.67 40.91 179.97 a H 185.50 1,582.59 b 31.26 45.84 177.10 ab 0 215.84 1,714.67 a 27.84 c 44.59 169.17 b 200 197.50 1,627.67 a 33.75 b 42.50 176.48 a 400 184.67 1,434.42 b 39.67 a 42.17 182.55 a SEM 14.04 59.54 2.83 2.55 2.24 BW vitamin E 0.13 0.94 0.011 0.67 0.26 BW 0.44 0.0001 0.29 0.39 0.028 0.30 0.008 0.022 0.76 0.001 a c Means within a column without a common superscript differ significantly (P < 0.05). dietary vitamin E increased the number of white ovarian follicles (Table 2) and, interestingly, decreased the fractional yolk weight (Figure 1). These findings confirm that experimental treatment induces obesity and its related reproductive failure. During avian egg production, estrogen mediates marked increases in hepatic lipid production and changes in the diameter of assembled very-low density lipoprotein (VLDL). A nearly complete shift from generic VLDL (approximately 70 nm in diameter), which transports lipids to peripheral tissues, to yolk-targeted VLDL (approximately 30 nm), which supplies the yolk with energy-rich lipid, has been observed in the plasma of laying domestic fowl [10]. Overfeeding increased liver synthesis, yolktargeted VLDL content, and its diameter because ester acts as a one of the main VLDL core components. Changing VLDL content alters the physicochemical properties of assembled lipoproteins and availability of them for hen ovarian follicles [11, 12]. The activity of hepatic 7α-hydroxylase was reduced in rats fed with high levels of vitamin E [13]. Also, it has been reported that antioxidants such as vitamin E reduce the breakdown of apolipoprotein B in lipoproteins such as VLDL, which means they can continue lipoprotein metabolism pathway and converted to the form of low-density lipoprotein, which is the main carrier of in blood [14, 15]. The -lowering activity of tocotrienols is ascribed to the ability of the side chain of tocotrienols to increase cellular farnesol, which in turn signals the proteolytic degradation of 3-hydroxy-3-methyl-glutarylcoenzyme A reductase, the enzyme responsible for the production of [16]. In the present study, we suggest that vitamin E, though similar in humans and rats in its effect on metabolism, decreased the content of lipoproteins assembled for joining to ovarian follicles. A change in the chemical composition of yolk lipoproteins altered the physical characteristics of yolk and decreased the fractional weight of yolk (Figure 1).

Zaghari et al.: VITAMIN E AND REPRODUCTION 813 Therefore, added vitamin E to the diet of H hens decreased the content of yolk precursor, increased availability of them for ovarian follicles, and, finally, increased the number of hierarchy follicles and egg production. Furthermore, in the present study, the concentration of high-density lipoprotein significantly increased (Table 4). By this observation, we propose that added dietary vitamin E also changes the metabolic direction of in broiler breeder hens. Similar to results obtained in the present study, Sahin et al. [17] reported that supplemental vitamin E in Japanese quail decreased concentrations of egg yolk. Mohiti-Asli and Zaghari [18] reported that egg yolk concentrations decreased linearly by antioxidant vitamin supplementation in commercial layer hens, and vitamin E was more effective than vitamin C. The literature provides strong evidence that vitamin E intake much higher than the current recommendations can contribute to or improve human and layer hen health [19 22]. CONCLUSIONS AND APPLICATIONS 1. Adding vitamin E to the diet of broiler breeder hens has the potential to reduce fractional yolk weight. Therefore, it is a good tool for manipulating egg quality in aged broiler breeder hens. 2. Feeding vitamin E at levels 4 times (400 vs. 100 mg/kg of diet) above the value recommended by strain management guide can decrease blood TAG and change the metabolic direction of in heavy broiler breeder hens. REFERENCES AND NOTES 1. Taherkhani, R., M. Zaghari, M. Shivazad, and A. Zare-Shahneh. 2010. A twice-a-day feeding regimen optimizes performance in broiler breeder hens. Poult. Sci. 89:1692 1702. 2. Chen, S. E., J. P. McMurty, and R. L. Walzem. 2006. Overfeeding-induced ovarian dysfunction in broiler breeder hens is associated with lipotoxicity. Poult. Sci. 85:70 81. 3. 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