Performance and Carcass Quality of Commercial Broiler Strains

OZODO Applied P o u l q Sdmq Inc

PERFORMANCE AND CARCASS QUALITY OF COMMERCIAL BROILER STRAINS M.E ' FARRAN', R E IUIALIL, M.G. UWAYJAN, and V. M.ASHKARIAN

Primary Audience: Broiler Breeders, Production Managers, Researchers

The continuing effort made by breeding DESCRIPTION OF PROBLEM companies to produce broiler chickens with The rapid growth of the modem broiler is accompanied by increased carcass and abdominal fat that are of concern to the consumer and the processor [l].Heredity, among other factors, has been reported to affect the carcass yield [2] and, to a varying degree, the fat deposition in broiler chickens [3, 4, 5, 61. Sex differences are also known to influence carcass fat [Iand abdominal fat deposition [4,81. 1

To whom correspondence should be addressed

improved production traits necessitates continuing evaluation of the selected strains. The broiler breeder strains commonly used by the broiler industry in the Middle East are Arbor Acres (AA), Ross (R), Lohman (L), Hybro G (HG), and Hybro N (HN) [9]. These broiler strains are imported as 1-day-old chicks. Informationon performance and management of these strains is typically obtained from literature made available by the breeder

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Department of Animal Sciences, Faculty of Agricultural and Food Sciences, American University of Beirut, P.O.Box 11-0236; Beirut, Lebanon Phone: 961-3-334306 FAX 961-1-744460 E-mail: [email protected] RN.WJ Faculty of Sciences, Lebanese University, Beirut, Lebanon

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companies. However, this information does not necessarily apply to regional environmental conditions. The objective of the present study was to compare the performance, carcass yield, and body composition of these commercial broiler strains raised by the broiler industry in Lebanon.

by infrared lights placed in each pen. Continuous lightingwas provided to the birds. Starter, grower, and withdrawal diets were provided from 0 to 21,22 to 41, and 42 to 49 days, respectively (Table 1). The crude protein content of the starter, grower, and withdrawal diets was 22,21, and 18%, respectively. All diets contained 3200 kcal ME/kg. The diets met or exceeded the broiler chicken nutrient requirements [lo]. Water and mash feed were available for adlibihrm consumption.The birds received the necessaryvaccines required for disease protection. In an attempt to maintain a uniform litter microflora in all pens, 5 kg of litter per pen was collected and mixed well every week before being redistributed among all pens. Live body weight (LBW) and feed intake were measured and feed:gain ratio (FC) was calculated for each pen at 21 and 49 days of age. At the end of the experimental period, 10 birds from each pen, representing average pen body welght, were selected and slaughtered, processed, and manually eviscerated. The abdominal fat pad (AFF') was removed from each carcass and weighed according to Kubena et ul. [ll]. The ready-to-cook (RTC) carcass welght was recorded after removing the viscera, m,giblets, preen gland, shanks,

MATERIALSAND METHODS

INGREDIENT Yellow corn (ground) Soybean meal (44%

CP)

M e a n oil Limestone

STARTER

GROWER

WITHDRAWAL

53.7

56.00

62.16

35.00 4.00 1.34

35.04

30.45

5.60

4.36

1.27

1.18

3.78 1.32

-

-

Dicalcium phosphate

1.39

1.14

DL-methionine

0.28

0.17

0.26

Rsh meal (72% CP)

Salt, non-iodized

1.19

0.24

0.25

Vitamiarace mineral premuP

0.25

0.25

0.25

~ m p r oH i -E~

0.05

0.05

-

crude protein ME! (kcavkg)

22.0 3200

21.0 3200

18.0

3200

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In Experiment 1, the performance and carcass yield of AA, HN, and HG broiler strains were studied; R, L, and AA strains were used in Experiment 2. The experimental design, diets, and management conditions followed in both experiments were similar. However, carcass composition was determined only in Experiment 2. Experiment 1 was conducted in the winter and Experiment2 in the spring of 1993. Hatching eggs of similar weight (60 to 65 g) were collected from commercial broiler breeder flocks of around 38 wk of age. The eggs were incubated and hatched in a commercial hatchery. The day-old chicks were vent sexed,weighed, and randomly distributed among 18 floor pens (3.3 x 1.5 m), with 45birds per sex per strain in each pen. Heating was provided during the first 25 days of age

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and head from the eviscerated carcass. The RTC carcasses were stored in sealed plastic bags at -22°C. Then these birds were analyzed, in Experiment 2, for moisture, crude protein, and crude fat composition [l2]. The data from males and females were analyzed by one-way ANOVA, with strain being the main variable following the GLM procedure [B].’Ifeatment means with probability of differences lower than 5% were compared using Duncan’s multiple range test.

RESULTS ANDDISCUSSION In Experiment 1, the average LBW of males and females of the AA strain at 21 and 49 days of age was heavier (P< .05) than that of the HN and HG strains (Table 2). There was no statistical difference in LBW, however, between those of HN and HG strains. Similarly, the FC at 21 days reflected the same trend that was observed with LBW, and both males and females of the AA strain scored significantly lower values (P< .OS). At 49 days of age, the FC of the AA strain in both sexes was significantly different from that of the HN strain, whereas the HG strain resulted in FC values in males and females that were not sigmficantlydifferent (P> .05) from those of AA and HN strains. The observed trend in performance response of male and female broiler chickens at 21 days in AA, HN, and HG strains was not observed in a random sample broiler test study conducted by Malone er al. [14] on severalbroiler crosses at 28 days of age. These researchers reported a change in BW and FC among the male, but not the female strains. In their study, they detected a sex-related trend at 8 wk of age

TABLE 2. Live body weight (LBW) and feed:gain ratio (FC) of broilers raised from hatch to 21 or 49 days of age (Experiment 1)

I“bMeansin

a column with no common supemxipts were significantlydifferent (P<,OS).

I

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whereby a change in LBW was observed among the female but not the male crosses. In the current study, however, the trend observed at 21 days was repeated at 7 wk of age, and the AA strain showed its superiority in terms of LBW over the other two strains. The absolute weights of AFP of AA, HN, and HG strains were 27.0,24.0, and 20.6 g. The corresponding percentages in males were 1.15, 1.13, and 0.95%, respectively (Table 3). The AA males had AFP welghts significantly heavier than those of HG males (P< .OS). No sign%cant strain differenceswere observed in females (Table 3). The lack of significance for percentage AFP in females could have resulted from the small sample size (10 birds per strain) or from the individualvariationsamong birds within a strain. In fact, Griffths et al. [3] reported a high coefficient of variation for A F P (26%) for four-way crosses. Although there were differences in LBW among the three strains, RTC yields of males and females (Table 3) were not different (P> .OS) and averaged around 67% for both sexes. These results agree with the findings of Merkley et al. [4], but contradict those of Orr et al. [2]. In Experiment 2, performance plus carcass quality and composition of male and female R, L, and AA broiler strains were studied. Body weights of the 21-day-old broiler chickens from either sex were not sign%cantly different (P> .05) among the three strains (“hble 4). The overall average across the three strains was 570 and 538 g for the males and females, respectively. Also, FC values during the same period were not significantly affected by strain (P>.O5). They

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TABLE 3. Weights of abdominal fat pad (AFP) and percentages of AFP and ready-tocookcarcass (RTC) relative

I

*bMeans in a column with no common superscripts were signifcantly different (Pi.OS).

FC value (1.90)that was significantly different (Pe .OS) from that of the AA strain (2.04).The FC data of this experiment agreed with those of Malone et al. [14],who raised the broiler strains to 8-wk post hatch. Abdominal fat pad weight, percent AFP, and percent RTC carcass appear in Table 5. In either sex, AFP weights were not significantly different among R, L, and A A strains.Percentage AFP of the R males was lower than that of L and AA strains and was significantlydifferent from that of AA males (P e .OS). The percentage AFP values of the females were not signifcantly different among the three strains studied and averaged 1.26%. The results for percentage AFP of males agreed with those of Littlefield [15] and Griffiths et al. [3]. They were not consistent, however, with those of Becker et al. [q. Ready-to-cook carcass yield of males was 67.9,66.6,and 65.8% (Table 5 ) for R,L, and AA strains, respectively (Pe.05). Also, females of the R strain had significantlyhigher RTC yield (67.1%) than those females of the L strain (65.8%), with an intermediate value for AA strain (66.5%). The current results

TABLE 4. Live body weights (LBW) and feed:gain ratio (FC) of broilers (Experiment 2)

SIRAIN

I

0 TO 21 DAYS

1

0 TO 49 DAYS

I‘bAveraw in the same column with no commonsuperscriptswere significantly different (P< .OS).

I

I

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averaged 1.50 and 1.51 g:g for males and females, respectively. Final LBW of the R, L, and AA strains was 2402,2330,and 2347 g for the males and 2057,1985,and 1986 g for the femalechickens, respectively (Table 4). In either sex, there were no differences in final LBW among the three strains (P> .05). The above results are in agreement with those of Becker et aZ. [5], who reported no significant differences in LBW of both 8-wk-oldmale and femalebroiler chickens from five strains. The current research results also agree with those of Malone et al. [14]with respect to 8-wk-old LBW of male, but not female, broiler chickens. The findings are not, however, consistent with those of Merkleyetal. [4]and Orretal. [2],who reported signifcant differences in LBW at 8 wk among five sexed broiler strains and differences in performance among eight strains of combined sex raised for 49 day post hatch, respectively. At 7 wk post hatch, FC values of the female chickens were not significantlydifferent (P > .05) and averaged 2.06 across the three strains. Ross males, however, had the lowest

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TABLE 5. Weights of abdominal fat pad (AFP) and percentagesof AFP and ready-to-wok carcass (RTC) relative

Iweans in the same column with no common sumrscrbtswere significantlydifferent (P < .05). Direct comparison with other data reported in the literature on broiler strain evaluation is not very accurate because of differences in genetic makeup, age of birds, and stage at which carcasses were prepared for analysis. To illustrate the latter, whole wMSS composition data (blood and feathers included) was reported by Wining et al. [7J, whereas Marion and Peterson [16] analyzed net carcass (without AFP) of different broiler brands randomly selectedfrom grocerystores. The data of Sizemore and Siege1 [l]were based, however, on analysis of RTC female carcasses including AFP. The poultry consumer of today is mainly interested in a leaner carcass. Accumulation of abdominal fat poses an economic and mechanical problem to the poultry producer, especially in the processing plants. The present research showed that some strains tend to deposit more abdominal and carcass fat than others, suggesting that fat deposition might have been given little consideration in the selection programs of some parent lines.

TABLE 6. Crude protein (CP), moisture, and crude fat (CF) composition of ready-to-wok carcasses

1abMeansin a column with no commonsuperscriptswere significantlydifferent (P < I

I

.OS).

I

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agreed with those of O n et al. [Z], whose work was on chilled carcass yield of combined male and female broiler chickens. They contradicted, however, the results of Merkleye t d . [4], who reported that fresh eviscerated carcass yield was not affected by either cross or sex. The results of RTC carcass composition of the three different strains for both sexes are presented in Table 6. The protein content of R males was significantly higher than that of L and AA males (18.8 vs. 18.3 and 18.2%, respectively). Similarly, the moisture content of R males (67.5%) was significantly higher than that of AA birds (65.9%), but not significantly different from that of L males (67.0%). Carcassfat of males followed a trend opposite to that of moisture, with AA males having the highest RTC fat content (12.5%) followed by L (11.4%) and R males (10.7%). Significant differenceswere detected only between R and AA strains for RTC fat composition. Female body composition results, however, were not different among the three strainsandaveraged 18.7, 66.1, and 12.1% for protein, moisture, and fat, respectively.

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CONCLUSIONS AND APPLICATIONS 1. Males and females of Arbor Acres strainswere sigruficantlyheavier than those of Hybro N and Hybro G strains at 21 and 49 days of age. 2. The feed conversionvalue of the Arbor Acres strain was significantlylower than that of the Hybro N strain only at 49 days of age. 3. Absolute abdominal fat pad weights of Hybro G males were significantlylower than those

of Arbor Acres males. 4. There was no significant differencein performance amongRoss, Lohman, and Arbor Acres

REFERENCES AND NOTES 1. Sizemore, F.C. and H.S Slegel, 1993. Growth, feed conversion, and carcass composition in females of four broiler crosses fed starter diets with different e n e y levels and energy to protein ratios. Poultry Sei. 2 2 16-2228.

2. Om, H.L, EC. Hun4 andCJ. Randal, 1984.Yield of carcass, parts, meat, skin, and bone of eight strains of broilers. Poultry Sci. 63:2197-2200. 3. Griffiths, L,S. Leson, and J.D. Summers, 1978. Studieson abdominal fat with four commercialstrains of male broiler chicken. Poultry Sci. 571198-1203.

4. Merkley, J.W., B.T. Weldand, G.W.Malone, and G.W. Chnloupka, 1980. Evaluation of fm commercial broiler crosses.2. Evisceratedyicldand componentparts. Poultry Sei. 591755-1760.

5. Becker, W.A., J.V.Spencer, LW. Mirosb, and J.A Verstrate, 1981.Abdominal and carcass fat in fm broiler strains. Poultry Sci. M):69MiW. 6. Kercn-Zvi, S, I. Nlr, Z Nltsan, and A cabpoer, 1990.Effect of dietay concentration of fat and energy on fat deposition in broilers dm ently selected for high or low abdominaladipose tissue.%. PoultrySci. 31:5W--516.

9. Farran, M.T., 1993.Statusof the poultry industry in Lebanon: Present impediments and su ested solutions for the future. Symposium on technicaknd economical grinazles for the production of Leghorn and broiler ree er flocks. Arab Organization for Agricultural Development, Cairo, Egypt. 10. National Research Council, 1984. Nutrient Requirements of Poultry. 8th Rev. Edition. Natl. Acad. Press, Washington, DC. 11. Kubcns, LF.,,T.C. Chmn, J.W. Deaton, and F.N. Reece, 1974.Factors influencingthe quantity of abdominal fat in broilers. 3. Dietary energy levels. Poultry Sci. 53974-938.

12.Assoelation of ONlcielAnalytlcp1Chemists, 1990. Official Methods of Analysii. 15th Edition. Assn. Offic. Anal. Chemists, Inc., Arlington, VA. 13. SAS Institute, 1992.SAS User's Guide: Statistics, Version 5 Edition. SAS Institute, Inc., Cary,NC. 14. Malone, G.W., G.W. Chnloupka, J.W. Merkley, and LH. Uttlefkld, 1979.Evaluation of fm commercial broiler crosses. 1. Grow-out performance. Poultry Sci.

P.V., Jr., O.P. Thomns, and EH. Bossard, of birds on the carcass 49, and 59 days of age. E g S c i . 52492497.

58509-515.

8. SompiyS, E & and K. &nfi 1983. Abdominal fat in 12- to 16-week-old broiler birds as influenced by age, sex, and strain. Poultry Sci. 621793-1799.

16. Marlon, J . E and M Peterson, 1987. Composition, pigmentation, and yield by parts of different brands of broilers in grocery stores. Poultry Sei. 66:1174-1179.

7.

1978. Effect of diet and ition of broilers at%,

15. Llttklkld, LH., 1972.Strain differencein uantity of abdominal fat in broilers. Poultry Sci. 51:1829qAbs).

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strains at 21 days of age. 5. Arbor Acres males had a significantlylower feed conversion than Ross and Lohman males at 49 days of age. 6. Ross males had the highest percent ready-to-cookyield and ready-to-cook protein among the three strains. 7. The Ross males had significantlylower percentage abdominalfat pad and percentage crude fat than the Arbor Acres males.