I ca1orie:grotein ratio was maintained at acceptable

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1 01997 Applied Poultry Science, Inc BROILER BONE STARTER DIET FAT LEVEL' PERFORMANCE, YIELD, AND CHARACTERISTICS AS AFFECTED BY E. DAVID PEEBLES2, J. D. BRAKE, and M. A. LATOUR Poultry Science Depament, P.O. Box 5188, Mississippi State University, Mississippi State, MS Phone: (601) FAX: (601) Primary Audience: Nutritionists, Broiler Producers, Field Service Personnel, Broiler Growers DESCRIPTION OF PROBLEM Hill and Dansky [ 11 have reported that the most practical method for increasing the energy density of diets is through the addition of fats and oils. Donaldson et al. [2] demonstrated that the inclusion of up to 33.8% fat in diets was well tolerated by growing chicks raised under normal conditions if the I ca1orie:grotein ratio was maintained at acceptable levels. In some cases, diets containing 30% fat allowed for more rapid growth than did rations with lower fat levels. Furthermore, the addition of 15% stabilized animal grease, a highly saturated fat, to a ration already containing 3.8% fat resulted in a slightly greater 1 Journal Article Number from the Mississippi Agricultural and Forestry Experiment Station. Use of trade names in this publication does not imply endorsement by Mississippi Agricultural and Forestry Experiment Station of these products, nor similar ones not mentioned. 2 To whom correspondence should be addressed

2 326 STARTER DIET FAT gain and improved feed conversion through 7 wk of age. However, the effects of dietary fat on weight and fat deposition in broilers are influenced by age [3, 41. Fat is not absorbed well by the chick until 8 days of age [4,5], and low fat absorption may influence calcium absorption [6]. In addition, high fat, high energy starter diets have been shown to influence the BW and body composition of broiler chicks at 11 days of age [4]. Increasing dietary fat level has been found to increase carcass fat content in birds [7]. Nevertheless, Leveille et al. [8] reported that the growth-promoting effect of 8% supplemental corn oil caused an increase in carcass protein and higher protein retention. Compared to less saturated fats such as poultry fat and corn oil, lard contains higher levels of stearic acid, a saturated fatty acid, and lower levels of the polyunsaturated fatty acids, linoleic and linolenic acid (Table 1). Research indicates that individual polyunsaturated fatty acids are absorbed better than saturated fatty acids [9]. Furthermore, in young broilers, the overall apparent metabolizable energy (AME) or dietary energy value of fats has been found to decrease Iiearly with degree of saturation [lo]. Lard, as a processing by-product, has become more available to the poultry industry in the state of Mississippi as a cheaper dietary fat source, but there is a lack of information on the effects of added dietary lard through 21 days of age on the growth and body composition of broilers. The objective of this study was to assess the effect of feeding various levels of added fat (lard), hence various energy levels, during the starter period, on the perfor- mance, carcass yield, and bone characteristics of broiler chickens grown to market weight. MATERIALS AND METHODS GENERAL A total of 3600 broiler chicks were wingbanded and randomly assigned to six dietary treatment groups of 600 birds each. Males and females were grown separately with each treatment being allotted six replicates per sex, for a total of 72pens with 50 birds per pen. The pens were randomized with respect to sex and dietary treatment. Each bird initially occupied m2 of floor space. Fresh pine shavings were used in floor pens. Birds were provided with continuous light. Feed and water were available for ad libitum consumption. DIETS The birds received non-isocaloric starter diets formulated to contain various levels of added lard with the megacaloric percentages of al major nutrients held constant. These diet formulations prevented a fiber dilution effect. A Starter 1 (Sl) diet was administered from approximately 0 to 10 days of age, with levels of 0,3, or added lard, and a Starter 2 (S2) diet was administered from approximately 11 to 21 days of age at a level of either 3 or added lard. At approximately 21 days of age, all buds were provided a common grower diet. A total of 2 lb (907 g) of starter diet per bird was made available. Each bird was allotted 227 g of the S1 diet and 680 g of the S2 diet, and transitions from one diet to the next were TABLE 1. Fatty acid content (percentages of total fatty acids) of lard in comparison to that of corn oil and poultry fat I POULTRY FAT Percentage of saturated fatty acids Percentage of unsaturated fatty acids Saturated:Unsaturated ratio of fatty acids

3 ~ PEEBLES et al. Research Report 327 TABLE 2. Ingredient percentage and calculated analysis of starter diets INGREDIENT Ground yellow corn Soybean meal (48% CP) Fishmeal, Menhaden (60% CP) ADDED FAT LEVEL 0% I 3 yo % Lysine TSAA Calcium Available phosphorus Sodium I Total fat I 3.16 I 5.96 I 9.75 *Supplied the following toeach k of finished feed: Vitamin A, 11,OOO IU cholecalciferol, 2750ICU; vitamin E, 22IU vitamin BIZ, 13.2 p ; nboflavin,$.7 m ; niacin, 385 mg; d-pantothenic acid, 13.2 mg; choline, 382 mg; selenium 0.2 p m; d biotin, 011 mg; manfmey, b mg; zinc, 50 mg; iron, 30 m copper, 5 mg; iodine, 0.5 mg; menadionesodiun bisul?ite, 4.96 m ; folic acid, 1. mg, pyndoxlne, 4.7 mg; thiamine, f8 mg; ethoxyquin, 55 mg. Supplied by Hoffman LaRoche Ltd., &ley, NJ made upon complete consumption of the previous diet. Table 2 shows the composition and calculated analysis of the starter diets, which met or exceeded NRC recommendations [ll] or industry standards. All possible combmations of the three S1 diets and two S2 diets yielded six total dietary treatments [12]. DATA COLLECTION Average live BW, feed consumption, and caloric conversion (CC) were determined for each pen at 42 days of age. Caloric conversion was calculated as kcal of ME consumed per lb of BW gain. Carcass and bone analyses were performed on three average-weight birds per pen at 44 days of age. On day 43, three birds that were 2 of the mean BW of each pen were selected and banded. Feed was withdrawn 10 hr prior to processing of the birds. At 44 days of age, selected birds were weighed at the rearing facility and transported in coops to the processing plant. Each bird was exsanguinated by stunning knife and bled for 90 sec, scalded at 60 C for 2 min, and defeathered in a rotary picker. Feet, necks, and viscera were manually removed. The carcasses were rinsed and placed in an ice water bath for 1 hr. After 1 hr, the carcasses were removed from the ice water, drained, and placed in plastic bags, tightly sealed and kept on ice. The birds were cut into parts later the same day. Carcass analyses included percentage chilled carcass weight, fat pad weight, front and back half weights, and left breast fillet weight. Analyses of the left tibia bone included percentage fat and bone ash. Bone drying, fat extraction, and ashing procedures were performed as described by Garlich et al. [13]. The cartilage heads of all bones were removed upon defleshing prior to drying. Bone fat was expressed as

4 328 STARTER DIET FAT a percentage of dry bone weight, and bone ash was expressed as a percentage of fat-free dry bone weight. RESULTS AND DISCUSSION There were no interactions of S1 and S2 diet in either sex for any of the parameters examined. Only main effects due to either S1 or S2 diet were observed. The 3 and S1 diets increased BW in both males and females, whereas Bw was greater in birds fed the S2 diet compared to those fed the S2 diet only in males at day 42 (Table 3). Caloric conversions in both sexes through 42 days were not affected by either the S1 or S2 diet. Latour et al. [4] demonstrated that exogenous lard at the level was not readily absorbed by the posthatch chick through 11 days of age. Data obtained by Blanch et al. [14] for 2-wk-old broiler chicks have also confirmed the nutritive superiority of oils, which are predominantly unsaturated, over fats based more on saturated fatty acids. Wiseman et al. [15] increased the free fatty acid content and decreased the ratio of unsaturated to saturated TABLE 3. Body weights (9) in male and female broilers at 42 days of age that received 0, 3, or added lard from 0 to 10 days of age (Sl diet) and 3 or added lard from 11 to 21 davs of aae IS2dietl I Pooledx PooledF 0% MALE I S2Diet I I * Sb t C af bk 2049Sa-C a Pooled F t t k C C t b a-C a fatty acids in fat blends by increasing the proportion of tallow (a saturated fat) to soybean oil (a more unsaturated fat). The increase in free fatty acid content and decrease in the ratio of unsaturated to saturated fatty acids lowered the AME of the fat in broilers. We therefore expected that lard would be less effective than more unsaturated fat sources in increasing the energy density of broiler diets. However, in this study, starter diets with energy levels increased by added lard promoted broiler growth without affecting CC. Because feed allotments and CC were similar for the different levels of the S1 and S2 diets, the increased energy densities of the diets evidently allowed for increased growth. These results were similar to those of Donaldson et al. [2], which showed that increased levels of saturated fats in broiler diets promote BW gain. Furthermore, the ca1orie:protein ratios of the different experimental diets in the present study were similar and were maintained at acceptable levels, as were those utilized by Donaldson et al. [2]. These data combined with those of Wiseman et al. [15] suggest that although added lard promoted growth, the use of a more unsaturated fat source at the same levels may better stimulate growth by increasing the energy densities of the diets and improving fat utilization. The effects of dietary fat on weight gain are influenced by age [3,4] and the amount of fat added to the diet [16, 171. Wiseman and Salvador [18] have found the AME of saturated and unsaturated fats to increase between 1.5 and 3.5 wk of age in broilers, with the rate of increase being greater in the saturated fat source. Decreased AME of fats withincreased degree of saturation has also been found to be pronounced in younger chicks [lo] and was related to a reduced apparent availability of fatty acids in conjunction with lower levels of bile production [19]. These effects were evident in the present study in the differential effects of dietary fat level in the S1 and S2 periods on BW. An enhanced ability of older birds (11-21 days of age) to utilize higher levels of lard may therefore have caused the birds fed added fat in the S2 diet to experience a significantly greater increase in BW than those fed S2 diets. Nonetheless, these data demonstrate a clear sex influence on the utilization of dietary fat for growth during both time periods.

5 PEEBLESetal. Research Report 329 Percentages of total chilled carcass, front half, and left breast fillet weights were increased in males fed the S1 diet (Table 4). The use of 8% added corn oil increased carcass protein in an earlier study by Leveille et al. [8]; however, the S1 diet also increased carcass yield in males although it contained lard, which is more saturated than corn oil. Percentage fat pad weight was increased in males fed either the 3 or S1 diet. Percentage bone fat was higher in males fed S1 dietscornpared to controls; those fed the S1 diet, however, had a similar percentage bone fat compared to controls and birds fed the S1 diet. Males fed S2 diets had a TABLE4. Percentage total chilled carcass, front half, and left breast fillet weights in male broilers at 44 davs of aae that received or added lard 0% Pooled I 70.7@? ? ? 71.71? 71.11? Sb? 70.6Sb a? Pooled: I I Pooled X FROhT HALF (%) 0% ? ? Ib2 37.Mb a Pooled I 37.66? ? higher percentage bone fat than those fed S2 diets (Table 5). As reported in other work [q, higher dietary fat levels increased carcass fat in this study, but this effect was limited to males and the S1 period. The S2 diet had no effect on carcass yield or bone ash in males or females. Added dietary lard during the S2 period did not yield a greater increase in carcass fat in the older birds despite an increase in the availability of dietary energy. The S1 diet did not affect carcass yield in females and bone ash in both sexes. However, as noted in earlier studies (41, early exposure to added dietary fat may cause differences in body composition that can carry through to market age. Effects TABLE 5. Percentage abdominal fat pad and bone fat weights in male broilers at 44 days of age that received 0,3, or added lard from 0 to 10 davs of age (Sl dietj and 3 or added lard from il to 21 daw of aae IS2 diet) Pooledx S2Diet I 52 Pooled Z 0% ? 1.51? 1.56-c ? 1.69? 1.54? Sb+ 1.61a2 1.60a BONE FAT (%) Pooled X 0% I 18.82? I I 22.26? 18.52bt a Pooled: Pooled Z 0% 6.64f e b 6.66 rt b a *Mean +SEM a9bpooled means within parameter and S1 or 52 diet with no common letter differ significantly (P1.05). a bpooled means within parameter and S1 diet with no common letter differ significantly (PS.05).

6 330 JAPR STARTER DIET FAT of the S1 period (0-10 days) on yield in the present study support these earlier findings. As indicated by the lack of dietary effects on percentage of fat-free bone ash, early fat supplementation apparently did not influence calcium and phosphorus metabolism. CONCLUSIONS AND APPLICATIONS 1. Adding 3 or dietary lard between 11 and 21 days of age does not adversely affect BW at 42 days and carcass fat at 44 days in broilers. 2. Adding 3 or dietary lard between 0 and 10 days of age increases 42-day BW in both sexes and 44-day carcass yield in males; however, associated increases in abdominal and bone fat of males may also occur at 44 days of age. 3. The influences of 3 and added dietary lard between 0 and 10 days of broiler age were not related to changes in CC. 4. The beneficial effects of the added lard outweighed those of the level only in males and were limited to increased 42-day BW when fed as part of the S2 diet and 44-day carcass yield when fed as part of the S1 diet. 5. Lard may be a cost-effective energy source for use in broiler starter diets, particularly in states like Mississippi where this processing by-product has become more readily available. 6. The level of added lard may prove economical as a dietary supplement for increased growth and carcass yield in male broilers. 1. Hill, G. and L Dansky, Studies of the energy requirements of chickens. Poultry Sci. 33: Donaldson, W.E, G.F. Combs, G.L Romaser, and W.C. Supplee, Studies on energy levels in poultry rations. 2. Tolerance of growing chicks to dietary fat. Poultry Sci. 36: Essary, EO. and LE Dawson, Qualityof fryer carcasses as related to protein and fat levels in the diet. 1. Fat deposition and moisture pick-up during chilling. Poultry Sci. N Lalour, MA, ED. Peebles, C.R Boyle, and J.D. Brake, The effects of dietary fat on growth performance, carcass composition, and feed efficiency in the broiler chick. Poultry Sci Renner, R and F.W. Hill, The utilization of corn oil, lard, and tallow by chickens of various ages. Poultry Sci Lloyd, LE, B.E McDonald, and EW. Crampton, Essential macroelements. Pages in: Fundamentals of Nutrition. 2nd Edition. W.H. Freeman and Company, San Francisco, CA. 7. Donaldson, WE, G.F. Combs, and G.C. Romaser, The effect of calorie-protein ratio of the ration on growth, nutrient utilization, and body composition of chicks. Poultry Sci. 35: Leveille, G.A., D.R Romsos, Y.Y. Yeh, and EK. O Hea, Lipid biosynthesis in the chick. A consideration of site of synthesis, influence of diet, and possible regulatory mechanisms. Poultry Sci. 54:107S Sklan, D.S., Digestionand absorption oflipids in chicks fed triglycerides or free fatty acids: Synthesis of monoglycerides in the intestine. Poultry Sci. 58: Wiseman, J. and F. Salvador, The influence of free fatty acid content and degree of saturation on the apparent metabolizable energy value of fats fed to broilers. Poultry Sci REFERENCES AND NOTES 11. National Research Council, Nutrient Requirements of Poultry. 10th Rev. Edition. Natl. Acad. Press, Washington, DC. 12. A 3 [Sl diet] X 2 [S2 diet] factorial arrangement of treatments within each sex was analyzed for statistical significance using the GLM Procedure of SAS. Angular transformations (arc sine of the square root of the propo,rtion affected) were performed on all percentage data pnor to analysis. Statements of significance were based on PS.05 unless otherwise indicated. 13. Garlic4 J., C. Morris, and J. Brake, External bone volume. ash. and fat-free drv weight of femurs of laying hens fed diets deficient or adkquag in phosphorus. Poultry Sci. 61: Blanch, A, A.C. Barroela, M.D. Baucells, and F. Pucw 1995.Thenutritivevalueof dietaryfatsin relation to their chemical composition. Apparent fat availability and metabolizable energy in two-week-old chicks. Poultry Sci Wiseman, J., F. Salvador, and J. Craigon, Prediction of the apparent metabolizable energy content of fats fed to broiler chickens. Poultry Sci. 70: Ha@, P.H. and C.R Creger, Effects of varying dietary protein and energy levels on growth rate and body fat in broilers. Poultry Sci. 59: Jensen. LS.. A. Brenes. and K. Takahashi Effect o f early nutrition on abdominal fat in broilers. Poultry Sci. 66: Wiseman, J. and F. Salvador, Influence of age, chemical composition, and rate of inclusion on the apparent metabolizable energy of fats fed to broiler chicks. Br. Poultry Sci. 30: Wiseman, J. and M. Lessire, Interaction between fats of differing chemical content: Apparent availability of fatty acids. Br. Poultry Sci