- Email: [email protected]
Effects of glycerol on the growth performance, internal organ weights, and drumstick muscle of broilers
©2013 Poultry Science Association, Inc.
Effects of glycerol on the growth performance, internal organ weights, and drumstick muscle of broilers E. Topal* and M. Ozdogan†1 *Turkish Ministry of Agriculture and Rural Affairs, İzmir, Turkey; and †Adnan Menderes University, Faculty of Agriculture, Department of Animal Science, Aydın, Turkey Primary Audience: Nutritionists, Poultry Growers, Feed Suppliers, Researchers, Zootechnicians SUMMARY In this study, we evaluated the effect of various amounts of crude glycerol on the growth performance, internal organ weights, and chemical composition of drumstick muscles of broiler chickens. A total of 360 Ross 308 broiler chicks (1 d old) received diets with 0, 40, or 80 g of glycerol/kg of diet for 42 d. Body weight gain was improved (P < 0.01) with the inclusion of 40 or 80 g of glycerol/kg of diet at 21 d, whereas broilers fed the diet with 80 g of glycerol/kg had the highest (P < 0.05) BW gains at 42 d. These levels of crude glycerol did not statistically affect feed consumption, but the inclusion of glycerol improved the FCR at 0 to 21 d of age and 0 to 42 d of age (P < 0.05). No negative effect of glycerol inclusion was observed on the carcass yield or the internal organ weights of broilers except for the heart weight of males. Glycerol inclusion at 40 or 80 g/kg of diet can be used as an effective source of energy in broilers, especially from 0 to 21 d of age. In addition, inclusion of glycerol significantly decreased ether extract in the drumstick muscles of both males (P < 0.05) and females (P < 0.01). Key words: broiler, drumstick, glycerol, performance 2013 J. Appl. Poult. Res. 22:146–151 http://dx.doi.org/10.3382/japr.2012-00589
DESCRIPTION OF PROBLEM Crude glycerol production is expected to increase because of an increase in biodiesel production. Crude glycerol is a by-product of the processing of oil in the biodiesel and chemical industries. It contains methanol, water, sodium chloride, and potassium chloride [1]. Some studies have been carried out to assess its energy value in animal feeds [2–4]. Osman et al. [5] conducted a study of glycerol to examine 1
Corresponding author: [email protected]
its effect on metabolic activity and animal health in relation to consumption level. Some positive results have been reported in studies examining the use of glycerol as an energy source in laying hens and broilers [6–11]. In addition, Groesbeck et al. [1] examined the improvement in pellet quality when using glycerol. Some studies have been related to using glycerol in broiler nutrition, but less well known are the effects of different levels of glycerol on weights of some internal organs and the chemical composition
Topal and Ozdogan: EFFECT OF GLYCEROL of the drumstick muscle in addition to growth performance and blood parameters in broilers. The purpose of the study was to investigate the effect of glycerol inclusion on the growth performance, internal organ weights, and chemical composition of the drumstick muscle in broiler chickens.
MATERIALS AND METHODS Experimental Design and Feeding All experimental procedures using birds were conducted in accordance with the European guidelines for the care and use of animals for research purposes (Recommendation 2007/526/ EC), and they were approved by the local ethics committee of Adnan Menderes University. A total of 360 one-day-old Ross 308 broiler chicks were placed in 12 floor pens (30 birds/pen) and randomly assigned to 3 dietary treatments (4 replicates/treatment). Wood shavings were used as the bedding material based on Ross [12] recommendations. Broilers were fed a starter diet (0 to 21 d of age) and a finisher diet (22 to 42 d of age). The chicks were fed ad libitum 1 of 3 diet groups containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80). The crude glycerol was obtained from a commercial biodiesel production facility that used sunflower-corn-soybean oil in a commercial company [13]. The experiment lasted for 42 d. The ME of glycerol used in formulation was 3,527 kcal/kg [7]. The diets were prepared according to the requirements of broilers based on NRC [14] recommendations (Table 1). The BW at 1, 21, and 42 d of age and the feed consumption at 21 and 42 d of age were measured. At the same time, the BW gain and FCR [feed consumption (g)/BW gain (g)] were calculated. A total of 48 broilers were randomly selected for analysis of serum, carcass yields, and internal organ weights (2 males and 2 females per pen). The average BW of the randomly sampled male and female broilers were 2,919.8 and 2,408.7 g, respectively. The BW of the selected males and females were similar to average pen weights. After slaughtering, the broilers were defeathered, eviscerated, and chilled in ice water. The carcasses were then dissected, and the internal organs were collected from each bird. The drum-
147
stick muscle was immediately separated from the left tibias by removing the skin, bones, and connective tissue. The drumstick muscle and abdominal fat were frozen and stored in a freezer at −20°C until further analyses. After thawing, the meat samples were minced separately using a blender with horizontal cutting blades. The glycerol was analyzed according to AOAC methods [15]. The crude glycerol consisted of 826 g/kg of glycerol, 0.3 g/kg of methanol (gas chromatography with flame-ionization detection), 118 g/kg of moisture (AOAC method 984.20), 6.4 g/kg of CP (AOAC method 990.03), 1.0 g/kg of ether extract (AOAC method 920.39), and 48.1 g/kg of ash (AOAC method 942.05). For the chemical composition of the drumstick muscle, DM (AOAC method 934.01), CP (AOAC method 976.05), ether extract (AOAC method 920.39), and ash content (AOAC method 942.05) were determined according to AOAC procedures [15]. Organ Traits After dissection, the internal organs (liver, kidneys, proventriculus, gizzard, and heart) were weighed. The carcass without giblets (% of BW) was weighed to determine hot dressed yield. The weights of the internal organs relative to BW were calculated in these chicks. Statistical Analysis The experimental data were analyzed by ANOVA using the GLM procedure of SAS [16]. Differences among means were tested using Tukey’s multiple comparisons test and were declared significant at P < 0.05. Each feature (internal organ weights, chemical composition of the drumstick muscle) was analyzed separately, and results were displayed together (male and female). The experimental unit was the pen.
RESULTS AND DISCUSSION Inclusion of glycerol (GLYC 40 or GLYC 80) in the diets affected some growth parameters (Table 2). Although the BW gains were higher in the 2 glycerol treatments at 0 to 21 d (P < 0.01), only broilers fed the GLYC 80 diet
JAPR: Review
148 Table 1. Ingredients and chemical composition of diets1 (g/kg as fed) 1 to 21 d of age Item Ingredient Glycerol Corn Soybean meal Sunflower oil Limestone Dicalcium phosphate Salt l-Lysine dl-Methionine Vitamin mix2 Mineral mix3 Nutrient composition, g/kg DM4 Ash4 CP4 Ether extract4 Calcium5 Available phosphorus5 Methionine + cystine5 Lysine5 ME,5 kcal/kg
22 to 42 d of age
GLYC 0
GLYC 40
GLYC 80
GLYC 0
GLYC 40
GLYC 80
— 469.0 430.0 60.0 11.0 20.0 3.0 1.0 2.0 3.0 1.0
40.0 423.0 437.0 60.0 10.0 20.0 3.0 1.0 2.0 3.0 1.0
80.0 375.0 445.0 60.0 10.0 20.0 3.0 1.0 2.0 3.0 1.0
— 525.5 373.0 65.0 9.0 18.5 3.0 — 2.0 3.0 1.0
40.0 476.5 382.0 65.0 9.0 18.5 3.0 — 2.0 3.0 1.0
80.0 424.5 393.0 66.0 9.0 18.5 3.0 — 2.0 30 1.0
91.63 6.95 23.10 8.50 1.0 0.5 0.92 1.36 3,100
91.36 7.18 23.35 8.33 1.0 0.5 0.91 1.36 3,103
90.77 7.43 23.45 8.15 1.0 0.5 0.90 1.37 3,101
91.65 7.83 21.23 9.13 0.9 0.4 0.86 1.14 3,202
91.30 7.90 21.38 8.95 0.9 0.4 0.86 1.15 3,200
90.75 7.98 21.51 8.76 0.90 0.4 0.85 1.17 3,200
1
Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80). Supplied the following per kilogram of diet: retinyl acetate, 3.6 mg; cholecalciferol, 0.04 mg; α-tocopherol, 50 mg; menadione, 5 mg; thiamine, 3 mg; riboflavin, 6 mg; niacin, 25 mg; calcium pantothenate, 12 mg; pyridoxine, 5 mg; cyanocobalamin, 0.03 mg; folic acid, 1 mg; d-biotin, 0.05 mg; choline chloride, 400 mg; salinomycin sodium, 60 mg. 3 Supplied the following per kilogram of diet: manganese (MnO), 80 mg; iron, (Fe2SO4∙H2O), 60 mg; zinc (ZnO), 60 mg; copper (CuSO4), 5 mg; cobalt (CoSO4), 0.2 mg; iodine (KI), 1 mg; selenium (Na2SeO4), 0.15 mg. 4 Analyzed chemical composition, according AOAC International methods [15]. 5 The nutrient content of diets was calculated according to the method of Dale and Batal [24]. 2
had the highest BW gains at 42 d (P < 0.05). The statistical differences in BW gain between groups fed diets with (GLYC 40 or GLYC 80) and without (GLYC 0) glycerol were especially seen at 0 to 21 d. The inclusion of glycerol did not change the feed consumption of the groups. At the same time, the FCR values in the GLYC 40 and GLYC 80 groups improved statistically at 0 to 21 d or 0 to 42 d of age (P < 0.05). The glycerol treatments significantly improved BW, resulting in a significant improvement in feed conversion. The positive effects of glycerol inclusion may have been related to undeveloped gastrointestinal organs of chicks at 0 to 7 d of age. It has been stated that the gastrointestinal organs secrete insufficient amounts of digestive juices and the villi are not well developed enough to work regularly during the first weeks of life [17–21]. However, compared with some
energy feeds, glycerol has a simple biochemical structure. Therefore, glycerol may be a source of easily digested energy. The bioavailability of glycerol in broilers is thought to be higher than that of other energy sources except for oils and glucose. In the feed industry, glycerol can be included in the diets as a practical energy source for broilers. The amounts of oil or fat in the rations were more than 6% (at least 6% sunflower oil in the rations). In a similar study, Simon et al. [6] found that the best results for BW gain were obtained in broilers fed 5 and 10% glycerol within diets containing 0, 15, 20, or 25% pure glycerol in the diets. The GLY 40 and GLY 80 diets had no significant effects on the feed consumption of broilers. In contrast, the FCR of broilers in the GLYC 40 and GLYC 80 groups were better at 0 to 21 d and 0 to 42 d of age in the present study. The
Topal and Ozdogan: EFFECT OF GLYCEROL
149
Table 2. Growth performance of broilers from 1 to 42 d of age1 Age
GLYC 0
BW gain, g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age Feed consumption, g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age FCR, g/g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age
GLYC 40
GLYC 80
SEM
P-value
761b 1,705 2,466b
812a 1,759 2,571ab
818a 1,777 2,595a
9.56 24.52 27.38
0.005 0.152 0.019
994.8 3,114 4,108
1,022.4 3,116 4,138
1,032.7 3,132 4,166
15.07 36.59 45.86
0.238 0.922 0.689
0.01 0.02 0.01
0.021 0.068 0.016
1.31a 1.83 1.67a
1.26b 1.77 1.61b
1.26b 1.76 1.61b
a,b
Means within the same row with different superscripts differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
inclusion of glycerol (40 or 80 g of glycerol/kg of diets) did not change the feed consumption of broilers. However, because of the high BW gains of the GLYC 40 and GLYC 80 groups, the FCR were better in the present study. No significant differences in feed consumption or FCR have been reported [9, 22, 23]. In contrast, according to Cerrate et al. [7], the feed consumption of broilers fed 100 g of glycerol/kg of diet was higher than that in other groups fed 0 and 50 g of glycerol/kg of diet. Simon et al. [6] found the best results for low feed consumption and FCR in broilers fed 50 or 100 g of glycerol within diets containing 0, 50, 100, 150, 200, or 250 g of pure glycerol/kg. The inclusion of glycerol in the diets did not affect the internal organ weights of male and female broilers, except for the heart weights
of males in the GLYC 80 group (Table 3). The heart weights of male broilers consuming the GLYC 80 diet were higher than those of males in the other groups (P < 0.05). We observed that inclusion of 40 and 80 g/kg of glycerol in the diets had no negative effect on carcass yields or the liver, kidney, gizzard, or proventriculus weights of males and females in the present study. The relative weights of some internal organs, such as the heart and liver, are known to be related to BW; therefore, we concluded that this difference was not based on feeding glycerol. Few studies have demonstrated the effect of diets containing glycerol on carcass yield. In a previous study, broilers consuming feeds with different amounts of glycerol did not differ significantly from birds fed the control diet for dressing percentage, the percentages of internal organs, or weight of
Table 3. Carcass yield and internal organ weights (g/100 g of BW) of broilers at 42 d of age1 Group Male GLYC 0 GLYC 40 GLYC 80 SEM P-value Female GLYC 0 GLYC 40 GLYC 80 SEM P-value a,b
Hot carcass yield
Liver
Kidney
Proventriculus
Gizzard
Heart
77.6 76.9 76.8 1.05 0.857
1.59 1.68 1.75 0.07 0.356
0.11 0.10 0.10 0.08 0.716
0.34 0.33 0.31 0.03 0.777
1.18 1.12 1.06 0.06 0.423
0.43b 0.48b 0.54a 0.02 0.033
78.3 76.8 78.6 0.71 0.238
1.86 1.80 1.89 0.11 0.829
0.10 0.11 0.12 0.01 0.460
0.39 0.38 0.36 0.05 0.908
1.18 1.24 1.21 0.11 0.923
0.53 0.52 0.52 0.05 0.999
Means within the same column each sex with different superscripts differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
JAPR: Review
150 Table 4. Chemical composition of drumstick muscle (%) of broilers at 42 d of age1 Group Male GLYC 0 GLYC 40 GLYC 80 SEM P-value Female GLYC 0 GLYC 40 GLYC 80 SEM P-value
DM
Ether extract
CP
Ash
31.6 29.0 30.1 1.47 0.492
8.8a 6.3b 6.0b 0.47 0.041
16.2 17.8 18.3 0.57 0.062
1.1 1.2 1.1 0.05 0.577
31.3 33.9 32.9 1.17 0.333
9.3a 6.7b 6.1b 0.38 0.001
17.8 17.8 17.7 0.81 0.994
1.1 1.1 1.0 0.04 0.063
a,b
Means within a column each sex with no common superscript differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
immune organs [23]. This result in the present study was in contrast with that of Coşkun et al. [9], who found that the liver, gizzard, and heart percentage weights of broilers fed a diet with 50 g of glycerol/kg were lower than those for the control group; however, the authors reported that the liver and heart weights of broilers fed 100 g of glycerol in the diets were higher than those for the control group. The decrease in ether extract levels of male (P < 0.05) and female (P < 0.01) broilers consuming the GLYC 40 and GLYC 80 diets was statistically significant (Table 4). We observed that the inclusion of 40 and 80 g of glycerol/ kg in the diets decreased the amounts of ether extract in the drumstick muscles of male and female broilers. The decreasing levels of ether extract in the drumsticks were thought to be due to the decreased ether extract values in the diets, related to reducing corn in the diets with glycerol inclusion. We have identified no previous studies that explain the effects of crude glycerol inclusion on any meat part of broilers.
CONCLUSIONS AND APPLICATIONS
1. Crude glycerol was successfully used as a source of energy in broiler diets. Glycerol derivatives are known to be intermediate reaction products of lipid and carbohydrate metabolism in the body. 2. Body weight gains of broilers fed diets with the inclusion of 40 or 80 g of glycerol/kg of diet were statistically
significant at 21 d, whereas only broilers fed the GLYC 80 diet had the highest (P < 0.05) BW gains at 42 d. The FCR of broilers consuming the GLYC 40 or GLYC 80 diet improved statistically at 0 to 21 d or 0 to 42 d of age. 3. Inclusion levels of 40 and 80 g of glycerol/kg of diet decreased ether extract levels in the drumstick muscle of male and female broilers. 4. Glycerol inclusion (40 and 80 g of glycerol/kg of diet) can be used for broilers as an effective source of energy at 0 to 21 d of age, and it decreases ether extract values in the drumsticks of broilers at 42 d of age. 5. In the future, according to the results in the present study, new studies should be conducted with broilers fed different inclusion levels of glycerol to elucidate the effects of different glycerol inclusion amounts on the growth performance of broilers and the chemical composition of the drumstick or breast muscles in broilers.
REFERENCES AND NOTES 1. Groesbeck, C. N., L. J. Mckinney, J. M. Derouchey, M. D. Tokach, R. D. Goodband, S. S. Dritz, J. L. Nelssen, A. W. Duttlinger, A. C. Fahrenholz, and K. C. Behnke. 2008. Effect of crude glycerol on pellet mill production and nursery pig growth performance. J. Anim. Sci. 86:2228–2236. 2. Pyatt, A., P. H. Doane, and M. J. Cecava. 2008. Effect of crude glycerin in finishing cattle diets. J. Anim. Sci. 85(Suppl. 1):412. (Abstr.)
Topal and Ozdogan: EFFECT OF GLYCEROL 3. Hansen, C. F., A. Hernandez, B. P. Mullan, K. Moore, M. Trezona-Murray, R. H. King, and J. R. Pluske. 2009. A chemical analysis of samples of crude glycerol from the production of biodiesel in Australia, and the effects of feeding crude glycerol to growing-finishing pigs on performance, plasma metabolites and meat quality at slaughter. Anim. Prod. Sci. 49:154–161. 4. Min, Y., F. F. Yan, Z. Liu, C. Coto, and P. W. Waldroup. 2010. Glycerin—A new energy source for poultry. Int. J. Poult. Sci. 9:1–4. 5. Osman, M. A., P. S. Allen, N. A. Mehyar, G. Bobe, J. F. Coetzee, K. J. Koehler, and D. C. Beitz. 2008. Acute metabolic responses of postpartal dairy cows to subcutaneous glucagon injections, oral glycerol, or both. J. Dairy Sci. 91:3311–3322. 6. Simon, A., H. Bergner, and M. Schwabe. 1996. Glycerol feed ingredient for broiler chickens. Arch. Anim. Nutr. 49:103–112. 7. Cerrate, S., F. Yan, Z. Wang, C. Coto, P. Sacakli, and P. W. Waldroup. 2006. Evaluation of glycerine from biodiesel production as a feed ingredient for broilers. Int. J. Poult. Sci. 5:1001–1007. 8. Dozier, W. A., B. J. Kerr, A. Corzo, M. T. Kidd, T. E. Weber, and K. Bregendahl. 2008. Apparent metabolizable energy of glycerin for broiler chickens. Poult. Sci. 87:317– 322. 9. Coşkun, B., A. Şehu, S. Küçükersan, and H. K. Köksal. 2007. The use of glycerol as a byproduct of biodiesel in poultry rations. Pages 24–31 in IV Natl. Anim. Nutr. Congr., Uludağ University, Bursa, Turkey. 10. Swiatkiewicz, S., and J. Koreleski. 2009. Effect of crude glycerin level in the diet of laying hens on egg performance and nutrient utilization. Poult. Sci. 88:615–619. 11. Yalçin, S., H. Erol, B. Özsoy, İ. Onbaşilar, S. Yalçin, and A. Üner. 2010. Effects of glycerol on performance, egg traits, some blood parameters and antibody production to SRBC of laying hens. Livest. Sci. 129:129–134. 12. Aviagen Inc. 2009. Ross Boiler Management Manual. Aviagen, Huntsville, AL. http://en.aviagen.com/assets/ Tech_Center/Ross_Broiler/Ross_Broiler_Manual_09.pdf.
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13. Diper Chemical Industry Inc., İzmir, Turkey. 14. NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. 15. AOAC International. 1997. Official Methods of Analysis. 16th ed. AOAC Int., Washington, DC. 16. SAS Institute. 1999. SAS User’s Guide: Statistics. Version 9.1 ed. SAS Inst. Inc., Cary, NC. 17. Almirall, M., M. Francesch, A. M. Perez-Vendrell, J. Brufau, and E. Esteve-Garcia. 1995. The differences in intestinal viscosity produced by barley and β-glucanase alter digesta enzyme activities and ileal nutrient digestibilities more in broiler chicks than in cocks. J. Nutr. 125:947–955. 18. Jin, S.-H., A. Corless, and J. L. Sell. 1998. Digestive system development in post-hatch poultry. World’s Poult. Sci. J. 54:335–345. 19. Uni, Z., Y. Noy, and D. Sklan. 1999. Posthatch development of small intestinal function in the poult. Poult. Sci. 78:215–222. 20. Baião, N. C., and L. J. C. Lara. 2005. Oil and fat in broiler nutrition. Braz. J. Poult. Sci. 7:129–141. 21. Wang, H., Y. Guo, and J. C. H. Shih. 2008. Effects of dietary supplementation of keratinase on growth performance, nitrogen retention and intestinal morphology of broiler chickens fed diets with soybean and cottonseed meals. Anim. Feed Sci. Technol. 140:376–384. 22. Lammers, P. J., B. J. Kerr, M. S. Honeyman, K. Stalder, W. A. Dozier, T. E. Weber, M. T. Kidd, and K. Bregendahl. 2008. Nitrogen-corrected apparent metabolizable energy value of crude glycerol for laying hens. Poult. Sci. 87:104–107. 23. Abd-Elsamee, M. O., Z. M. A. Abdo, M. A. F. ElManylawi, and I. H. Salim. 2010. Use of crude glycerin in broiler diets. Egypt. Poult. Sci. 30:281–295. 24. Dale, N., and A. Batal. 2003. Ingredient analysis table: 2003–2004 edition. Feedstuffs 75:16–17.
Effects of glycerol on the growth performance, internal organ weights, and drumstick muscle of broilers E. Topal* and M. Ozdogan†1 *Turkish Ministry of Agriculture and Rural Affairs, İzmir, Turkey; and †Adnan Menderes University, Faculty of Agriculture, Department of Animal Science, Aydın, Turkey Primary Audience: Nutritionists, Poultry Growers, Feed Suppliers, Researchers, Zootechnicians SUMMARY In this study, we evaluated the effect of various amounts of crude glycerol on the growth performance, internal organ weights, and chemical composition of drumstick muscles of broiler chickens. A total of 360 Ross 308 broiler chicks (1 d old) received diets with 0, 40, or 80 g of glycerol/kg of diet for 42 d. Body weight gain was improved (P < 0.01) with the inclusion of 40 or 80 g of glycerol/kg of diet at 21 d, whereas broilers fed the diet with 80 g of glycerol/kg had the highest (P < 0.05) BW gains at 42 d. These levels of crude glycerol did not statistically affect feed consumption, but the inclusion of glycerol improved the FCR at 0 to 21 d of age and 0 to 42 d of age (P < 0.05). No negative effect of glycerol inclusion was observed on the carcass yield or the internal organ weights of broilers except for the heart weight of males. Glycerol inclusion at 40 or 80 g/kg of diet can be used as an effective source of energy in broilers, especially from 0 to 21 d of age. In addition, inclusion of glycerol significantly decreased ether extract in the drumstick muscles of both males (P < 0.05) and females (P < 0.01). Key words: broiler, drumstick, glycerol, performance 2013 J. Appl. Poult. Res. 22:146–151 http://dx.doi.org/10.3382/japr.2012-00589
DESCRIPTION OF PROBLEM Crude glycerol production is expected to increase because of an increase in biodiesel production. Crude glycerol is a by-product of the processing of oil in the biodiesel and chemical industries. It contains methanol, water, sodium chloride, and potassium chloride [1]. Some studies have been carried out to assess its energy value in animal feeds [2–4]. Osman et al. [5] conducted a study of glycerol to examine 1
Corresponding author: [email protected]
its effect on metabolic activity and animal health in relation to consumption level. Some positive results have been reported in studies examining the use of glycerol as an energy source in laying hens and broilers [6–11]. In addition, Groesbeck et al. [1] examined the improvement in pellet quality when using glycerol. Some studies have been related to using glycerol in broiler nutrition, but less well known are the effects of different levels of glycerol on weights of some internal organs and the chemical composition
Topal and Ozdogan: EFFECT OF GLYCEROL of the drumstick muscle in addition to growth performance and blood parameters in broilers. The purpose of the study was to investigate the effect of glycerol inclusion on the growth performance, internal organ weights, and chemical composition of the drumstick muscle in broiler chickens.
MATERIALS AND METHODS Experimental Design and Feeding All experimental procedures using birds were conducted in accordance with the European guidelines for the care and use of animals for research purposes (Recommendation 2007/526/ EC), and they were approved by the local ethics committee of Adnan Menderes University. A total of 360 one-day-old Ross 308 broiler chicks were placed in 12 floor pens (30 birds/pen) and randomly assigned to 3 dietary treatments (4 replicates/treatment). Wood shavings were used as the bedding material based on Ross [12] recommendations. Broilers were fed a starter diet (0 to 21 d of age) and a finisher diet (22 to 42 d of age). The chicks were fed ad libitum 1 of 3 diet groups containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80). The crude glycerol was obtained from a commercial biodiesel production facility that used sunflower-corn-soybean oil in a commercial company [13]. The experiment lasted for 42 d. The ME of glycerol used in formulation was 3,527 kcal/kg [7]. The diets were prepared according to the requirements of broilers based on NRC [14] recommendations (Table 1). The BW at 1, 21, and 42 d of age and the feed consumption at 21 and 42 d of age were measured. At the same time, the BW gain and FCR [feed consumption (g)/BW gain (g)] were calculated. A total of 48 broilers were randomly selected for analysis of serum, carcass yields, and internal organ weights (2 males and 2 females per pen). The average BW of the randomly sampled male and female broilers were 2,919.8 and 2,408.7 g, respectively. The BW of the selected males and females were similar to average pen weights. After slaughtering, the broilers were defeathered, eviscerated, and chilled in ice water. The carcasses were then dissected, and the internal organs were collected from each bird. The drum-
147
stick muscle was immediately separated from the left tibias by removing the skin, bones, and connective tissue. The drumstick muscle and abdominal fat were frozen and stored in a freezer at −20°C until further analyses. After thawing, the meat samples were minced separately using a blender with horizontal cutting blades. The glycerol was analyzed according to AOAC methods [15]. The crude glycerol consisted of 826 g/kg of glycerol, 0.3 g/kg of methanol (gas chromatography with flame-ionization detection), 118 g/kg of moisture (AOAC method 984.20), 6.4 g/kg of CP (AOAC method 990.03), 1.0 g/kg of ether extract (AOAC method 920.39), and 48.1 g/kg of ash (AOAC method 942.05). For the chemical composition of the drumstick muscle, DM (AOAC method 934.01), CP (AOAC method 976.05), ether extract (AOAC method 920.39), and ash content (AOAC method 942.05) were determined according to AOAC procedures [15]. Organ Traits After dissection, the internal organs (liver, kidneys, proventriculus, gizzard, and heart) were weighed. The carcass without giblets (% of BW) was weighed to determine hot dressed yield. The weights of the internal organs relative to BW were calculated in these chicks. Statistical Analysis The experimental data were analyzed by ANOVA using the GLM procedure of SAS [16]. Differences among means were tested using Tukey’s multiple comparisons test and were declared significant at P < 0.05. Each feature (internal organ weights, chemical composition of the drumstick muscle) was analyzed separately, and results were displayed together (male and female). The experimental unit was the pen.
RESULTS AND DISCUSSION Inclusion of glycerol (GLYC 40 or GLYC 80) in the diets affected some growth parameters (Table 2). Although the BW gains were higher in the 2 glycerol treatments at 0 to 21 d (P < 0.01), only broilers fed the GLYC 80 diet
JAPR: Review
148 Table 1. Ingredients and chemical composition of diets1 (g/kg as fed) 1 to 21 d of age Item Ingredient Glycerol Corn Soybean meal Sunflower oil Limestone Dicalcium phosphate Salt l-Lysine dl-Methionine Vitamin mix2 Mineral mix3 Nutrient composition, g/kg DM4 Ash4 CP4 Ether extract4 Calcium5 Available phosphorus5 Methionine + cystine5 Lysine5 ME,5 kcal/kg
22 to 42 d of age
GLYC 0
GLYC 40
GLYC 80
GLYC 0
GLYC 40
GLYC 80
— 469.0 430.0 60.0 11.0 20.0 3.0 1.0 2.0 3.0 1.0
40.0 423.0 437.0 60.0 10.0 20.0 3.0 1.0 2.0 3.0 1.0
80.0 375.0 445.0 60.0 10.0 20.0 3.0 1.0 2.0 3.0 1.0
— 525.5 373.0 65.0 9.0 18.5 3.0 — 2.0 3.0 1.0
40.0 476.5 382.0 65.0 9.0 18.5 3.0 — 2.0 3.0 1.0
80.0 424.5 393.0 66.0 9.0 18.5 3.0 — 2.0 30 1.0
91.63 6.95 23.10 8.50 1.0 0.5 0.92 1.36 3,100
91.36 7.18 23.35 8.33 1.0 0.5 0.91 1.36 3,103
90.77 7.43 23.45 8.15 1.0 0.5 0.90 1.37 3,101
91.65 7.83 21.23 9.13 0.9 0.4 0.86 1.14 3,202
91.30 7.90 21.38 8.95 0.9 0.4 0.86 1.15 3,200
90.75 7.98 21.51 8.76 0.90 0.4 0.85 1.17 3,200
1
Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80). Supplied the following per kilogram of diet: retinyl acetate, 3.6 mg; cholecalciferol, 0.04 mg; α-tocopherol, 50 mg; menadione, 5 mg; thiamine, 3 mg; riboflavin, 6 mg; niacin, 25 mg; calcium pantothenate, 12 mg; pyridoxine, 5 mg; cyanocobalamin, 0.03 mg; folic acid, 1 mg; d-biotin, 0.05 mg; choline chloride, 400 mg; salinomycin sodium, 60 mg. 3 Supplied the following per kilogram of diet: manganese (MnO), 80 mg; iron, (Fe2SO4∙H2O), 60 mg; zinc (ZnO), 60 mg; copper (CuSO4), 5 mg; cobalt (CoSO4), 0.2 mg; iodine (KI), 1 mg; selenium (Na2SeO4), 0.15 mg. 4 Analyzed chemical composition, according AOAC International methods [15]. 5 The nutrient content of diets was calculated according to the method of Dale and Batal [24]. 2
had the highest BW gains at 42 d (P < 0.05). The statistical differences in BW gain between groups fed diets with (GLYC 40 or GLYC 80) and without (GLYC 0) glycerol were especially seen at 0 to 21 d. The inclusion of glycerol did not change the feed consumption of the groups. At the same time, the FCR values in the GLYC 40 and GLYC 80 groups improved statistically at 0 to 21 d or 0 to 42 d of age (P < 0.05). The glycerol treatments significantly improved BW, resulting in a significant improvement in feed conversion. The positive effects of glycerol inclusion may have been related to undeveloped gastrointestinal organs of chicks at 0 to 7 d of age. It has been stated that the gastrointestinal organs secrete insufficient amounts of digestive juices and the villi are not well developed enough to work regularly during the first weeks of life [17–21]. However, compared with some
energy feeds, glycerol has a simple biochemical structure. Therefore, glycerol may be a source of easily digested energy. The bioavailability of glycerol in broilers is thought to be higher than that of other energy sources except for oils and glucose. In the feed industry, glycerol can be included in the diets as a practical energy source for broilers. The amounts of oil or fat in the rations were more than 6% (at least 6% sunflower oil in the rations). In a similar study, Simon et al. [6] found that the best results for BW gain were obtained in broilers fed 5 and 10% glycerol within diets containing 0, 15, 20, or 25% pure glycerol in the diets. The GLY 40 and GLY 80 diets had no significant effects on the feed consumption of broilers. In contrast, the FCR of broilers in the GLYC 40 and GLYC 80 groups were better at 0 to 21 d and 0 to 42 d of age in the present study. The
Topal and Ozdogan: EFFECT OF GLYCEROL
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Table 2. Growth performance of broilers from 1 to 42 d of age1 Age
GLYC 0
BW gain, g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age Feed consumption, g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age FCR, g/g 0 to 21 d of age 22 to 42 d of age 0 to 42 d of age
GLYC 40
GLYC 80
SEM
P-value
761b 1,705 2,466b
812a 1,759 2,571ab
818a 1,777 2,595a
9.56 24.52 27.38
0.005 0.152 0.019
994.8 3,114 4,108
1,022.4 3,116 4,138
1,032.7 3,132 4,166
15.07 36.59 45.86
0.238 0.922 0.689
0.01 0.02 0.01
0.021 0.068 0.016
1.31a 1.83 1.67a
1.26b 1.77 1.61b
1.26b 1.76 1.61b
a,b
Means within the same row with different superscripts differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
inclusion of glycerol (40 or 80 g of glycerol/kg of diets) did not change the feed consumption of broilers. However, because of the high BW gains of the GLYC 40 and GLYC 80 groups, the FCR were better in the present study. No significant differences in feed consumption or FCR have been reported [9, 22, 23]. In contrast, according to Cerrate et al. [7], the feed consumption of broilers fed 100 g of glycerol/kg of diet was higher than that in other groups fed 0 and 50 g of glycerol/kg of diet. Simon et al. [6] found the best results for low feed consumption and FCR in broilers fed 50 or 100 g of glycerol within diets containing 0, 50, 100, 150, 200, or 250 g of pure glycerol/kg. The inclusion of glycerol in the diets did not affect the internal organ weights of male and female broilers, except for the heart weights
of males in the GLYC 80 group (Table 3). The heart weights of male broilers consuming the GLYC 80 diet were higher than those of males in the other groups (P < 0.05). We observed that inclusion of 40 and 80 g/kg of glycerol in the diets had no negative effect on carcass yields or the liver, kidney, gizzard, or proventriculus weights of males and females in the present study. The relative weights of some internal organs, such as the heart and liver, are known to be related to BW; therefore, we concluded that this difference was not based on feeding glycerol. Few studies have demonstrated the effect of diets containing glycerol on carcass yield. In a previous study, broilers consuming feeds with different amounts of glycerol did not differ significantly from birds fed the control diet for dressing percentage, the percentages of internal organs, or weight of
Table 3. Carcass yield and internal organ weights (g/100 g of BW) of broilers at 42 d of age1 Group Male GLYC 0 GLYC 40 GLYC 80 SEM P-value Female GLYC 0 GLYC 40 GLYC 80 SEM P-value a,b
Hot carcass yield
Liver
Kidney
Proventriculus
Gizzard
Heart
77.6 76.9 76.8 1.05 0.857
1.59 1.68 1.75 0.07 0.356
0.11 0.10 0.10 0.08 0.716
0.34 0.33 0.31 0.03 0.777
1.18 1.12 1.06 0.06 0.423
0.43b 0.48b 0.54a 0.02 0.033
78.3 76.8 78.6 0.71 0.238
1.86 1.80 1.89 0.11 0.829
0.10 0.11 0.12 0.01 0.460
0.39 0.38 0.36 0.05 0.908
1.18 1.24 1.21 0.11 0.923
0.53 0.52 0.52 0.05 0.999
Means within the same column each sex with different superscripts differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
JAPR: Review
150 Table 4. Chemical composition of drumstick muscle (%) of broilers at 42 d of age1 Group Male GLYC 0 GLYC 40 GLYC 80 SEM P-value Female GLYC 0 GLYC 40 GLYC 80 SEM P-value
DM
Ether extract
CP
Ash
31.6 29.0 30.1 1.47 0.492
8.8a 6.3b 6.0b 0.47 0.041
16.2 17.8 18.3 0.57 0.062
1.1 1.2 1.1 0.05 0.577
31.3 33.9 32.9 1.17 0.333
9.3a 6.7b 6.1b 0.38 0.001
17.8 17.8 17.7 0.81 0.994
1.1 1.1 1.0 0.04 0.063
a,b
Means within a column each sex with no common superscript differ significantly (P < 0.05). Chicks were fed ad libitum 1 of 3 diets containing either 0 (GLYC 0), 40 (GLYC 40), or 80 g/kg of crude glycerol (GLYC 80).
1
immune organs [23]. This result in the present study was in contrast with that of Coşkun et al. [9], who found that the liver, gizzard, and heart percentage weights of broilers fed a diet with 50 g of glycerol/kg were lower than those for the control group; however, the authors reported that the liver and heart weights of broilers fed 100 g of glycerol in the diets were higher than those for the control group. The decrease in ether extract levels of male (P < 0.05) and female (P < 0.01) broilers consuming the GLYC 40 and GLYC 80 diets was statistically significant (Table 4). We observed that the inclusion of 40 and 80 g of glycerol/ kg in the diets decreased the amounts of ether extract in the drumstick muscles of male and female broilers. The decreasing levels of ether extract in the drumsticks were thought to be due to the decreased ether extract values in the diets, related to reducing corn in the diets with glycerol inclusion. We have identified no previous studies that explain the effects of crude glycerol inclusion on any meat part of broilers.
CONCLUSIONS AND APPLICATIONS
1. Crude glycerol was successfully used as a source of energy in broiler diets. Glycerol derivatives are known to be intermediate reaction products of lipid and carbohydrate metabolism in the body. 2. Body weight gains of broilers fed diets with the inclusion of 40 or 80 g of glycerol/kg of diet were statistically
significant at 21 d, whereas only broilers fed the GLYC 80 diet had the highest (P < 0.05) BW gains at 42 d. The FCR of broilers consuming the GLYC 40 or GLYC 80 diet improved statistically at 0 to 21 d or 0 to 42 d of age. 3. Inclusion levels of 40 and 80 g of glycerol/kg of diet decreased ether extract levels in the drumstick muscle of male and female broilers. 4. Glycerol inclusion (40 and 80 g of glycerol/kg of diet) can be used for broilers as an effective source of energy at 0 to 21 d of age, and it decreases ether extract values in the drumsticks of broilers at 42 d of age. 5. In the future, according to the results in the present study, new studies should be conducted with broilers fed different inclusion levels of glycerol to elucidate the effects of different glycerol inclusion amounts on the growth performance of broilers and the chemical composition of the drumstick or breast muscles in broilers.
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