INTRODUCTION. MATERIALS AND METHODS Birds and Diets. E. D. Peebles,*,3 C. D. Zumwalt,* P. D. Gerard, M. A. Latour,*,4 and T. W.

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1 Market Age Live Weight, Carcass Yield, and Liver Characteristics of Broiler Offspring from Breeder Hens Fed Diets Differing in Fat and Energy Contents 1,2 E. D. Peebles,*,3 C. D. Zumwalt,* P. D. Gerard, M. A. Latour,*,4 and T. W. Smith* *Department of Poultry Science and Experimental Statistics Unit, Mississippi State University, Mississippi State, Mississippi ABSTRACT The effects of energy level, fat type, and weights were higher in female broilers compared to those fat level in breeder hen diets on subsequent offspring market age live BW, carcass yield, and liver characteristics from breeder hens at 29 and 36 wk of age were evaluated. At 22 wk of age, six dietary treatments were imposed. Dietary treatments contained: 1) 3.0% added poultry fat (PF) and 467 (high energy) kcal/hen per day at peak production (CPP), 2) no added fat and high energy, 3) 3.0% added PF and 430 (low energy) CPP, 4) no added fat and low energy, 5) 1.5% added PF and 449 (moderate energy) CPP, and 6) 3.0% added corn oil (CO) and moderate energy. Breeder age influenced Day 43 broiler live BW, percentage total carcass and front-half yields, and liver moisture contents. Furthermore, wet and dry liver of male broilers from 29-wk-old breeder hens. Live BW was higher in broilers from hens fed low-energy diets compared with moderate-energy diets and 3.0% compared to 1.5% PF diets. Percentage liver DM was higher in females compared to male broilers from hens fed 3.0% CO and moderate energy and was highest in male and female broilers from hens fed 1.5% PF and moderate energy. Percentage wet liver weight and liver DM were higher and liver moisture content was lower in broilers from hens fed 1.5% compared to 3.0% PF diets. Overall, energy and fat levels in breeder diets had subsequent influences on market age weight and liver characteristics of broilers. (Key words: broiler, broiler breeder, carcass quality, dietary fat, liver) 2002 Poultry Science 81:23 29 INTRODUCTION Spratt and Leeson (1987) have shown that protein intake of broiler breeders has no effect on BW of offspring. Conversely, increasing broiler breeder energy intake increases carcass protein and reduces fat in male offspring at 41 d of age (Spratt and Leeson, 1987). Furthermore, Triyuwanta et al. (1992) found that increased maternal BW and feed allowances of dwarf broiler breeders exerts positive effects on BW of progeny through 40 d of age. Body weight gain of broiler offspring between 0 and 21 d of growout has been shown to increase with breeder hen ages between 35, 51, and 63 wk (Peebles et al., 1999a). Added fat (1.5%) has been shown to be an effective energy 2002 Poultry Science Association, Inc. Received for publication May 14, Accepted for publication September 27, This is Journal Article No. J-9858 from the Mississippi Agricultural and Forestry Experiment Station supported by MIS Use of trade names in the publication does not imply endorsement by Mississippi Agricultural and Forestry Experiment Station of those products or of similar ones not mentioned. 3 To whom correspondence should be addressed: dpeebles@ poultry.msstate.edu. 4 Current address: Department of Animal Sciences, Purdue University, 1151 Lilly Hall, West Lafayette, IN source in breeder diets, but compared to poultry fat (PF), corn oil (CO), a less saturated fat, increases 0-to-21-d BW gain and 22-to-42-d feed conversion in broiler progeny (Peebles et al., 1999a). Based on these results, impacts of maternal dietary fat source on subsequent slaughter yield at market age would be expected. In conjunction with the previously reported work using isocaloric diets containing different types and levels of added fat, Peebles et al. (1999b) also showed that breeder age influences broiler slaughter yield and that less saturated fat improves subsequent slaughter yield. The present study was designed to determine the combined and separate effects of energy level, fat type, and fat level in breeder diets on subsequent broiler slaughter yield characteristics. MATERIALS AND METHODS Birds and Diets Breeder management and diets were as described by Peebles et al. (2001). Briefly, hens were distributed into Abbreviation Key: CO = corn oil; CPP = kilocalories per hen day at peak production; DLV = percentage dry liver weight; FHCW = percentage front-half carcass weight; LM = percentage liver moisture content; NAF = no added fat diet; PF = poultry fat; TRT = treatment; WLV = percentage wet liver weight. 23

2 24 PEEBLES ET AL. TABLE 1. Ingredient percentages and calculated and determined analyses of breeder diets Test diets 1 Ingredient Yellow corn Soybean meal, 48% Wheat middlings Limestone Menhaden fishmeal Defluorinated phosphate Micronutrient premix Sodium chloride DL-methionine L-Lysine HCl, 78% Poultry fat Corn oil Dietary analysis CP, calculated CP, determined ME, calculated kcal/kg 2,940 2,940 2,709 2,709 2,826 2,826 Lysine, calculated TSAA, calculated Tryptophan, calculated Calcium, calculated Available phosphorus, calculated Sodium, calculated Ash, determined Moisture, determined Crude fat, calculated Crude fat, determined Linoleic acid, calculated Test diets contained: 1) 3.0% added poultry fat (PF) and 467 peak kcal/hen day (CPP), 2) no added fat and 467 CPP, 3) 3.0% added PF and 430 CPP, 4) no added fat and 430 CPP, 5) 1.5% added PF and 449 CPP, and 6) 3.0% added corn oil (CO) and 449 CPP. 2 Supplied the following per kilogram of finished feed: vitamin A acetate, 11,000 IU; cholecalciferol, 2,750 IU; α-tocopheral acetate, 22 IU; riboflavin, 7.7 mg; niacin, mg; d-pantothenic acid, 13.2 mg; folic acid, 1.1 mg; vitamin B 12,13µg; biotin, 110 µg; choline chloride, 441 mg; thiamine, 1.8 mg; pyridoxine, 4.7 mg; menadione sodium bisulfite, 4.96 mg; ethoxyquin, 55 mg; manganese, 55 mg; zinc, 50 mg; iron, 30 mg; copper, 5 mg; iodine, 0.50 mg; and selenium, 0.1 mg. Manufactured by Hoffman-LaRoche, Inc., Nutley, NJ pens that were randomly assigned to six dietary treatments with four replications per treatment (TRT). Each pen contained 20 females and 4 males. Upon initiation of lay at Week 22, females were limit-fed one of six basal corn-soybean mash diets (Table 1). Males were fed a common basal corn-soybean mash diet. All diets were formulated to meet or exceed NRC (1994) specifications. Based on percentage differences in calculated and determined CP levels, the actual daily intake levels of lysine, methionine, TSAA, and tryptophan by birds fed any of the six diets met or exceeded those recommended for broiler breeders by NRC (1994). The experimental diets contained various types and levels of added fat. The two different fat sources varied in fatty acid profile. The fatty acid compositions of each of the six different diets have been described by Peebles et al. (2001). Diets 1 and 2 allowed each bird to reach an energy intake of 467 kcal/ d at peak production (467 CPP), Diets 3 and 4 contained the lowest energy levels (430 CPP), and Diets 5 and 6 contained moderate energy levels (449 CPP). Diets 1 and 3 contained 3.0% added PF, Diets 2 and 4 contained no added fat (NAF), Diet 5 contained 1.5% added PF, and Diet 6 contained 3.0% added CO (Table 2). The respective abbreviations for Diets 1 through 6, as listed in Table 2, (%) are 3PF-467, NAF-467, 3PF-430, NAF-430, 1.5PF-449, and 3CO-449. Slaughter and Carcass Yield Approximately 1,400 eggs were collected at 29 wk, and 1,200 eggs were collected at 36 wk of breeder hen age. All eggs were incubated for determination of subsequent broiler carcass yield at 43 d. All eggs were stored at 15 C and were set on the fifth day after the start of egg collection each week. Prior to set, eggs were randomized within each replicate by day of collection at each week. After being allowed to reach room temperature, the eggs TABLE 2. Dietary treatments for broiler breeder hens Added Added ME at peak Diet fat type fat production (%) (kcal/hen/d) 1 Poultry None Poultry None Poultry Corn oil

3 BREEDER DIETARY FAT AND BROILER YIELD 25 TABLE 3. Ingredient percentages and calculated analysis of broiler starter, grower, and finisher diets Starter Grower Finisher Ingredient 1 3 wk 4 5 wk 6 wk (%) Corn Soybean meal, 48% Dicalcium phosphate Limestone Poultry fat DL-methionine Micronutrient premix NaCl Coban Calculated analysis CP ME, kcal/kg 3,194 3,194 3,194 Total fat Calcium Available phosphorus TSAA Lysine Supplied the following per kilogram of finished feed: vitamin A, 12,300 IU; cholecalciferol, 2,750 IU; vitamin E, 33 IU; riboflavin, 9.2 mg; niacin, 57.9 mg; d-pantothenic acid, mg; folic acid, 442 mg; vitamin B 12, 13.2 µg; biotin, 146 µg; choline chloride, 1,522 mg; thiamine, 4.5 mg; pyridoxine, 4.7 mg; menadione sodium bisulfite, 0.72 mg; manganese, 1.62 mg; zinc, 183 mg; iron, 574 mg; copper, 45 mg; and selenium, 0.5 mg. Supplied by Hoffmann-LaRoche, Inc., Nutley, NJ were randomly distributed by individual TRT replicate group in a Petersime Model 5 incubator. 5 Eggs were incubated at 37.5 C dry bulb and 28.3 C wet bulb temperatures. On Day 19, eggs were transferred to a Jamesway 252 A incubator 6 and set at 37.5 C dry bulb and 28.9 C wet bulb for hatching. Eggs were separated according to TRT replicate group within metal hatching trays. At hatch, chicks within the four replicates belonging to the same TRT group were rerandomized into three replicates for placement into floor pens. Floor pens contained fresh pine shavings. Replicate groups were randomly assigned to 1 of 18 pens. Each pen in a curtainsided growout house measured m (4.38 m 2 ) and contained 50 unsexed chicks. Pens were supplied with hanging bell waterers and tube feeders to provide access to water and feed ad libitum. Water drinkers and feeder pans were provided for the first week of the growout. Birds were provided with continuous light. Pen temperature was 32 C on Day 1 and was gradually lowered by approximately 3 C every 4 d through 12 d, thereafter a minimum temperature of 24 C was maintained. Birds were provided standard broiler starter, grower, and finisher diets (Table 3). On Day 43, approximately three male and three female broilers were randomly selected from each pen, individually weighed at the rearing facility, and transported in coops to the processing plant. Feed was withdrawn 10 h prior to processing. The birds were slaughtered and handeviscerated on a small, partially automated poultry processing line. Livers were collected during evisceration and weighed. The processed carcasses were chilled by 5 Petersime Incubator Co., Gettysburg, OH Butler Manufacturing Co., Fort Atkinson, WI immersion in crushed ice and water for 2 h and weighed. The chilled carcasses were further-processed by removal of the abdominal fat pad and were split into front and back halves. Abdominal fat pad weight was obtained only at Week 36. The front half included the breast and wing portions, and the back half included the back and leg/thigh portions. Relative weights of the liver [wet (WLV) and dry (DLV)], processed chilled total carcass, abdominal fat pad, and front (FHCW) and back halves of the carcass were expressed as percentages of 43-d live broiler BW before slaughter. Furthermore, livers were dried and weighed as described by Peebles et al. (2001). Liver moisture weight was calculated as the difference between wet and dry liver weight. Liver moisture content (LM) was expressed as a percentage of wet liver weight. Statistical Analysis The experimental design was completely randomized. Six breeder hen dietary TRT with three replicates per TRT were utilized in all data analyses. A split-split-plot analysis was used to test for the effects of breeder hen dietary TRT (whole-plot), breeder hen age (sub-plot), broiler sex (sub-sub-plot), and their interactions on live weight, percentage carcass weight, FHCW, percentage back-half carcass weight, WLV, DLV, and LM. The effect of hen age on percentage abdominal fat pad weight was not analyzed because its determination was limited to Week 36. When interactions were significant, means were compared by Fisher s protected least-significant difference (Steel and Torrie, 1980). Angular transformations (arc sine of the square root of the proportion affected) were performed on all percentage data prior to analysis (Steel and

4 26 PEEBLES ET AL. TABLE 4. Type of effect tested and dietary treatment combination means compared for each contrast Contrast type 1 Treatment means compared High (467 CPP) vs. low (430 CPP) energy 1 and 2 vs. 3 and 4 High (467 CPP) vs. moderate (449 CPP) energy 1 and 2 vs. 5 and 6 Low (430 CPP) vs. moderate (449 CPP) energy 3 and 4 vs. 5 and 6 PF vs. CO across level 1, 3, and 5 vs. 6 PF vs. CO at the 3.0% level 1 and 3 vs vs. 3.0% level of PF 5 vs. 1 and 3 1 Diet 1 contained 3.0% added poultry fat (PF) and 467 peak kcal/d (CPP); Diet 2, no added fat and 467 CPP; Diet 3, 3.0% added PF and 430 CPP; Diet 4, no added fat and 430 CPP; Diet 5, 1.5% added PF and 449 CPP; and Diet 6, 3.0% added corn oil (CO) and 449 CPP. Torrie, 1980). All these data were further analyzed by a set of prespecified contrasts. The effects of energy level (430, 449, or 467 CPP), added fat type across level and only at the 3.0% level (PF or CO), and level of PF (1.5 or 3.0%) were tested (Table 4). All data were analyzed by a mixed-model approach with the mixed procedure on SAS software (1996). Akaike information criteria were used to choose between candidate models (Littell et al., 1996). Statements of significance were based on P 0.05, unless otherwise indicated. RESULTS There was a significant main effect due to breeder hen age on broiler live weight (P ), percentage carcass weight (P ), FHCW (P 0.03), and LM (P 0.04) (Table 5). Day 43 live weight, percentage carcass weight, FHCW, and LM were higher in broilers from 36-wk-old hens compared to those from 29-wk-old breeder hens. Day 43 live weight (P ) and LM (P 0.005) of male broilers were significantly greater than those of females across Weeks 29 and 36. Respectively, mean live weight and LM in male and female broilers, respectively, were 2,151 and 1,815 g (pooled SEM = 16.7) and 70.9 and 69.1% (pooled SEM = 0.45). In addition, percentage abdominal fat pad weight at Week 36 was significantly (P ) higher in females than in males. Mean percentage fat pad weights in male and female broilers at Week 36 were 1.71 and 2.13%, respectively (pooled SEM = 0.091). There were significant interactions of breeder age by broiler sex for WLV (P 0.03) and DLV (P 0.04) (Table 6). The WLV and DLV were greater in females compared to male broilers from 29-wk-old breeder hens. There was a significant (P 0.03) interaction of breeder dietary TRT by broiler sex for DLV (Table 7). Mean DLV was higher in females compared to male broilers from hens fed 3CO-449 diets. DLV was higher in male broilers from hens fed 1.5PF-449 compared to 3CO-449 diets and in female broilers from hens fed 1.5PF-449 compared to 3PF-467 or 3PF-430 diets. Contrast analyses also revealed that live weight was higher in broilers from hens fed low- compared to moderate-energy diets (P 0.03) and that live weight (P 0.04) and LM (P 0.02) were higher in broilers from hens fed 3.0% compared to 1.5% PF diets (Table 8). Conversely, WLV (P 0.05) and DLV (P 0.02) were significantly higher in broilers from hens fed 1.5% compared to 3.0% PF diets (Table 8). DISCUSSION The present data confirm previously reported work by Peebles et al. (1999b) that breeder age effects subsequent broiler growth and slaughter yield. Abdominal fat pad and liver characteristics were not examined by Peebles et al. (1999b). Nevertheless, age did not have similar effects on the 43-d parameters examined in both studies. Results from work by Peebles et al. (1999b) showed that broiler live weight at 43 d was higher in broilers from 51-wk-old breeders than for those from 63-wk-old hens, which, in turn, was higher than for those from breeder hens 35 wk of age. Percentage carcass weight and FHCW were higher in broilers from 63-wk-old breeders than those from breeder hens that were 35 or 51 wk of age. Previous and current results showed similar breeder age effects on only percentage carcass weight and FHCW. This disparity may be due to the differences in the hen ages compared in each study. Furthermore, slaughter live weight and percentage carcass weight were shown by Peebles et al. (1999b) to be significantly higher in male TABLE 5. Mean broiler live weight on Day 43, percentage chilled carcass weight, percentage front-half carcass weight (FHCW), and percentage liver moisture content (LM) at 29 and 36 wk of breeder age Live Carcass Week weight weight FHCW LM (g) (%) 29 1,939 b 66.5 b 35.5 b 69.1 b 36 2,027 a 71.1 a 36.7 a 70.9 a SEM a,b Means within parameter among week of breeder age with no common superscript differ significantly (P 0.05).

5 BREEDER DIETARY FAT AND BROILER YIELD 27 TABLE 6. Mean percentage wet (WLV) and dry (DLW) liver weights in male and female broilers from breeder hens at 29 and 36 wk of age WLV 1 DLV 2 Week Male Female Male Female (%) b 2.98 a 0.81 b 0.95 a a 2.76 a 0.80 a 0.84 a a,b Means within parameter and week of age among sex with no common superscript differ significantly (P 0.05). 1 SEM based on pooled estimate of variance = SEM based on pooled estimate of variance = than female broilers, whereas, in the current study, only live weight was significantly higher in males compared to females. Breeder age effects on broiler hatching egg characteristics such as egg weight, percentage eggshell and yolk weights, and yolk:albumen ratio have been established (Peebles et al., 2000). Latour et al. (1998) have also suggested that breeder age influences the utilization of yolk lipid by developing embryos. Furthermore, Peebles et al. (1999c) showed that embryos and their livers display differential accumulations of moisture and DM during incubation and that these differences exhibit distinctive associations with various yolk fatty acids. In a more recent report, Peebles et al. (2001) observed a breeder age effect on WLV in 18 d broiler embryos. Relative dry liver weight and the influence of embryo sex were not examined in that study; however, WLV was lower and relative dry embryo weight was higher for embryos from 27-wk-old breeder hens compared to those from 36-wk-old breeder hens. Taken together, these reports suggest that maternal age related changes in the absorption and metabolism of yolk lipids by broiler embryos affect total embryo DM and WLV differently. The current data further show that maternal age effects on broiler offspring liver characteristics are not limited to the embryonic period but may also ultimately affect the livers of market age birds. Most notable were the findings that WLV and liver DM were higher in females compared to male broilers from hens at only 29 wk of age, and that LM was lower in broilers at 29 wk when compared to those at 36 wk. Clearly, differences in the posthatch performance of broiler off- spring from young hens may be related to differences in the liver characteristics of those offspring. Upon comparing CO (1.5 and 3.0%), PF (1.5 and 3.0%), and lard (3.0%), it was shown that less saturated fat added at the 1.5% level may improve subsequent broiler slaughter yield (Peebles et al., 1999b). Because the diets used by Peebles et al. (1999b) were isocaloric, the effects of altered energy level alone were not assessed. The current investigation has shown that energy level, regardless of the added fat level and type used in the breeder diet, displays an independent effect in broiler offspring that extends into the market age period. In comparison to the moderate (449 CPP) energy level, the lowest (430 CPP) breeder dietary energy level resulted in a higher live weight at 43 d. Peebles et al. (1999b) reported that 43-d live weight and percentage slaughter carcass weight were increased significantly by using CO (highly unsaturated) rather than lard (highly saturated) and that FHCW was increased by using CO rather than PF, regardless of fat level. However, when compared across level and only at the 3.0% level in the present study, CO and PF did not affect 43-d live BW or slaughter yield differently. Poultry fat contains lower concentrations of unsaturated fatty acids than does CO. Added fat in hen diets can influence the yolk fatty acid profile of fresh eggs (Balnave, 1970; Ohtake and Hoshino, 1976; Cherian and Sim, 1991; Hargis et al., 1991; Ahn et al., 1995; Latour et al., 1998). Nevertheless, large differences in fatty acid saturation levels, as exist between CO and lard, may be necessary to cause differences in overall offspring performance due to fat TABLE 7. Mean percentage dry liver weight in male and female broilers from breeder hens fed Diets 1 through 6 1 Sex 3PF-467 NAF-467 3PF-430 NAF PF-449 3CO-449 Male 0.78 ab,x 0.78 ab,x 0.80 ab,x 0.83 ab,x 0.96 a,x 0.70 b,y Female 0.75 b,x 0.86 ab,x 0.81 b,x 0.94 ab,x 1.08 a,x 0.95 ab,x a,b Means within sex among diet with no common superscript differ significantly (P 0.05). x,y Means within diet among sex with no common superscript differ significantly (P 0.05). 1 SEM based on pooled estimate of variance = Diet 1 (3PF-467) contained 3.0% poultry fat (PF) and 467 peak kcal/d (CPP); Diet 2 (NAF-467), no added fat and 467 CPP; Diet 3 (3PF-430), 3.0% added PF and 430 CPP; Diet 4 (NAF-430), no added fat and 430 CPP; Diet 5 (1.5PF-449), 1.5% added PF and 449 CPP; and Diet 6 (3CO-449), 3.0% added corn oil (CO) and 449 CPP. Diet

6 28 PEEBLES ET AL. TABLE 8. Contrast means for mean broiler live weight at Day 43, percentage wet (WLV) and dry (DLV) liver weights, and percentage liver moisture content (LM) Parameter Contrast type SEM Live weight (g) WLV (%) DLV (%) LM (%) Low (430 CPP) vs. moderate (449 CPP) energy 2,023 a 2,008 b ,911 b 2,008 a a 2.73 b a 0.79 b b 71.3 a 0.60 a,b Means within parameter and contrast type with no common superscript differ significantly (P 0.05). type. Current results also showed that the 3.0% level of PF led to a higher 43-d live weight than did the 1.5% level of PF. If PF is added to breeder diets, it may be further inferred from these data that increased 43-d live broiler BW is potentiated by increasing PF levels from 1.5 to 3.0%. Previous work (Peebles et al., 2001), using the same breeder flock and diets as were used in the current investigation, showed no significant effects of diet on broiler embryogenesis. Thus, the subsequent effects of breeder dietary energy and fat on market age live weight demonstrated by these data were not associated with similar effects during embryogenesis. Evidently, the influence of hen dietary energy and fat content on broiler development via the egg may have latent and long-term effects that become manifest later in the growout period. It has also been demonstrated by Peebles et al. (1999a), that in relation to PF, CO, a less saturated fat, increased broiler BW gain through 21 d and feed conversion between 22 and 42 d when added to the diets of breeder hens. On the other hand, isocaloric breeder diets containing 1.5 and 3.0% levels of added CO, PF, and lard had no significant effects on broiler feed consumption, relative BW gain, and feed conversion through 21 d, water consumption through 14 d, or water/feed consumption ratio through 13 d (Peebles et al., 1998). These present data establish that maternal dietary fat intake has subsequent effects on 43-d wet and dry liver weight and moisture content of broiler offspring. More specifically, 1.5% added PF compared to 3.0% added PF led to higher wet and dry liver weights and a lower LM. In conjunction with a moderate energy level, 1.5% PF also led to a higher DLV than 3.0% CO in males and 3.0% PF with low- or high-energy levels in females. Peebles et al. (1998) found no significant effects of breeder dietary added fat level (1.5 and 3.0%) or fat type (CO, PF, or lard) on 22-d WLV. However, addition of lard to broiler diets has been shown to suppress WLV while increasing their protein and lowering their fat contents (Latour et al., 1994). Although dietary fat has little effect on the amount of fat in yolk, the fatty acid composition of yolk may be altered by that in the diet, particularly by highly unsaturated dietary fatty acids (Cruickshank, 1934; Ohtake and Hoshino, 1976; Latour et al. 1998). Because embryos are selective in deposition and oxidation of yolk fatty acids, the profiles of fatty acids found in yolk and those in embryonic tissues can be noticeably different (Donaldson, 1964). Nevertheless, Peebles et al. (1999c) found that relative liver DM was correlated positively with yolk palmitic acid and negatively with yolk oleic acid concentrations during late incubation. This result suggested a differential utilization of palmitic and oleic acids in the livers of offspring and, further, that the utilization of oleic acid may be important to increased liver DM synthesis. The possibility of differences in yolk palmitic and oleic acid percentages in hens fed 1.5% PF, 3.0% PF, and 3.0% CO may, therefore, serve as partial means by which these diets affected DLV and LM in market age broiler offspring. In this study, 43-d live weight increased, whereas DLV and WLV decreased in response to an increase in PF from 1.5 to 3.0%. Furthermore, a decrease in WLV occurred despite an increase in LM. Earlier findings (Peebles et al., 1999c) also showed that embryo and liver DM increases are not associated with yolk concentrations of all the same types of fatty acids. Growth and homeostasis are associated with the metabolic function of the liver. Nevertheless, these findings suggest that changes in yolk fatty acid profile can affect broiler liver and body characteristics differently during embryonic and posthatch periods. ACKNOWLEDGMENTS This work was funded in part by a grant from the US Poultry and Egg Association and by the Mississippi Agricultural and Forestry Experiment Station. The authors also express appreciation to Janice Orr for her expert secretarial assistance in the preparation of this manuscript. REFERENCES Ahn, D. U., H. S. Sunwoo, F. W. Wolfe, and J. S. Sim, Effects of linolenic acid and strain of hen on the fatty acid composition, storage ability, and flavor characteristics of chicken eggs. Poultry Sci. 74: Balnave, D., Essential fatty acids in poultry nutrition. World s Poult. Sci. J. 26:

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