Effects of dietary boric acid supplementation on performance in broilers
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Effects of dietary boric acid addition on growth performance, cholesterolemia, some carcass and tibia characteristics in different rearing periods in broiler chickens G. YILDIZ1, B.H. KOKSAL2*, O. SIZMAZ1 Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Ankara University, 06110, Diskapi, Ankara, Turkey Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Adnan Menderes University, 09016, Isikli, Aydin, Turkey
1 2
*Corresponding author:
[email protected]
SUMMARY
RÉSUMÉ
In this study, the effects of boric acid addition to broiler diets in different rearing periods on growth performance, cholesterolemia, carcass and some bone characteristics were investigated. For this purpose, 96 one day old broiler chickens (Ross 308) were randomly assigned in 4 equal groups according to the modalities of boron supplementation: whereas birds of the control group were fed with basal diets, the others were supplemented with boric acid (60 mg/kg of food/day) during the starting (first 21 days, group T1), the finishing (last 21 days, group T2) and the whole experimental (42 days, group T3) periods. Boric acid addition has induced no significant effects on growth performance, carcass characteristics and cholesterolemia but significant increased calcium and phosphorus deposition in tibia bone ash was evidenced in treated broilers, especially those supplemented for the finishing period. These results suggest that dietary boric acid supplementation may be a useful practice for improving bone characteristics in broilers.
Effets d’une supplémentation alimentaire en acide borique durant différentes périodes d’élevage sur la croissance, la cholestérolémie et quelques caractéristiques des carcasses et du tibia chez le poulet.
Keywords: Boron, dietary supplementation, broiler, growth performance, cholesterolemia, carcass, rearing period, bone (tibia), calcium.
Dans cette étude, les effets d’une supplémentation des rations alimentaires en acide borique au cours de différentes périodes d’élevage sur la croissance, la cholestérolémie, et quelques caractéristiques des carcasses et du tibia ont été analysés chez le poulet. Dans ce but, 96 poussins (Ross 308) de 1 jour ont été aléatoirement répartis en 4 groupes égaux en fonction des modalités de la supplémentation alimentaire : alors que les oiseaux contrôles ont été nourris avec les régimes alimentaires de base, les autres ont reçu une supplémentation en acide borique (60 mg/ kg d’aliment/jour) pendant la phase de démarrage (les 21 premiers jours, groupe T1), celle de finition (les 21 derniers jours, groupe T2) ou pendant toute la durée de l’expérimentation (42 jours, groupe T3). La supplémentation en acide borique n’a induit d’effet significatif ni sur la croissance, ni sur les caractéristiques des carcasses et ni sur la cholestérolémie mais des augmentations significatives des teneurs du tibia en calcium et en phosphore ont été mises en évidence, en particulier chez les oiseaux supplémentés durant la phase de finition. Ces résultats suggèrent qu’une supplémentation en acide borique pourrait être indiquée afin d’améliorer les caractéristiques osseuses des poulets.
Mots-clés : Bore, supplémentation alimentaire, poulet, croissance, cholestérolémie, carcasse, période d’élevage, os (tibia), calcium.
Introduction For very long time period (from 1920’s) it is known that boron (B) is an essential element for higher plants. Lately it has been understood that boron also plays a role in the metabolism of minerals, enzymes and steroid hormones in animals and humans [23, 27]. For a description, boron is a dark brown non-metal which is found in nature as borax, colemanite, boronatrocalcite, and boracite. In bone metabolism, boron interacts with Ca, vitamin D and Mg [3]. Furthermore, it has been shown that boron increases the secretion of some steroid hormones and prevents some bone deformations [17]. An increase in dietary boron content resulted with increase the concentrations of serum ionized calcium and lipid concentrations [18, 21]. Furthermore, the administration of chemicals containing boron to rats for 14 days caused significant decreases in low-density lipoprotein Revue Méd. Vét., 2013, 164, 4, 219-224
(LDL), cholesterol and triglyceride concentrations, while high-density lipoprotein (HDL) synthesis increased [9]. In another experiment, HUNT and NIELSEN [11] supplemented diets with B at various contents and either adequate or inadequate amounts of vitamin D3 and found a positive relationship between B and vitamin D3: boron supplementation improved chick body weight when the vitamin D3 content of the diet was adequate (2500 IU kg-1) and vitamin D3 was inadequate (125 IU kg-1). Eliot and EdwardS [5] using a factorial arrangement of treatments involving the addition of calcium, vitamin D3 and B to purified diets for broilers reported that B supplementation tended to increase bone ash and that there was a significant interaction between B and vitamin D3 on body weight gain. ROSSI et al. [25] observed increases in body weights in B supplemented broilers.
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Ingredients (%) Corn Soybean meal Full fat soybean Vegetable oil Meat and bone meal Limestone Dicalcium phosphate Salt Methionine Lysine VMM Chemical composition Crude proteins (CP, %) Metabolisable energy (kcal/kg) Boron (mg/kg)
YILDIZ (G.) AND COLLABORATORS Starter diet
Finisher diet
(1-3 weeks)
(3-6 weeks)
45.50 34.00 12.00 3.00 3.00 0.50 1.10 0.30 0.30 0.10 0.20
55.55 13.00 22.00 4.00 4.00 0.30 0.40 0.15 0.00 0.30 0.25
22.51 3048 15.85
19.45 3235 15.92
VMM: vitamin and mineral mix containing per kg diet: 15000 IU vitamin A; 5000 IU vitamin D3; 50 mg vitamin E; 10 mg vitamin K3; 4 mg vitamin B1; 8 mg vitamin B2; 5 mg vitamin B6; 0.025 mg vitamin B12; 50 mg niacin; 20 mg pantothenic acid; 2 mg folic acid 0.25 mg biotin; 75 mg ascorbic acid; 175 mg choline and 56 mg Mn; 140 mg Zn; 56 mg Fe; 10.5 mg Cu; 1.05 mg I; 0.28 mg Co; 0.28 mg Se; 0.7 mg Mo. Table I: Composition and chemical analysis of the broiler (starter and finisher) diets.
Boron has been examined as a possible nutritional factor in calcium (Ca) metabolism and as a factor in the development of normal bones [20]. Although the National Research Council [19] suggested that trace mineral supplements to chemically defined diets should contain at least 2 ppm B, the real B requirement for the different categories of poultry has not been determined yet [10, 22, 28]. Recent studies [16, 28-30] indicated that addition of boron or boric acid to broiler and laying hen’s diets induced no statistically significant effects on performance parameters. Similarly, it was also reported that 50 mg/kg boron addition to diets increased amount of bone ash but did not modify body weights in growing pullets [26]. However these effects of boron are variable depending on management, genotype, nutrient content of diets, as well as dietary boron content and its source. The aim of this study was to investigate the influence of dietary boron supplementation on growth performance, blood cholesterol concentrations, some carcass characteristics and mineralization of tibia in different rearing periods in broiler chickens.
Material and Methods Animals and protocol design
between 0-21 days, then with a finisher diet (20% CP and 3200 kcal/kg ME) between 22-42 days. Standard diets were based on corn and soybean meals (Table I). Dietary nutrient contents were based on the recommendations of the National Research Council for broilers [19]. Feeds were analyzed for crude protein, calcium, and total phosphorus according to the reference methods from AOAC [1]. The formula recommended by Turkish Standards Institute [12] was used to calculate the metabolisable energy. Feed and water were given ad libitum. A total of 96 one-day old male Ross-308 broiler chickens were randomly divided into 4 equal groups according to the dietary regimen and each group was constituted by 4 subgroups of 6 birds. Chicks in the control group were fed with standard diets whereas other birds were fed with standard diets supplemented with 60 mg/kg boric acid in different rearing periods: during the 1st and the 3rd weeks for the first treatment group (T1), during the 3rd and the 6th weeks for the second treatment group (T2) and during the whole experimental period for the third treatment group (T3). Diluted boric acid (17.5% boron) was used as a source of boron. The experimental protocol was approved by the local Ethic Committee of the Ankara University.
Performance and biochemical analyses
The birds (male Ross-308 broiler chickens) were housed in wire-bottomed pens fitted with electrical heaters. The initial temperature was 33°C (from day 0 to day 3) and was gradually reduced according to normal management practice by 2-3°C per week. Chicks were maintained on a 24-hours constant light schedule until the end of the experiment lasting 42 days.
During the experimental period, the performance of the broilers was evaluated by weekly recording body weights (BW), body weight gains (BWG), food intakes (FI) and food conversion ratios (FCR or food efficiency). FCR was calculated as the amount of food consumed per unit of body weight gain. Mortality was recorded daily.
Broilers have been fed with starter chick diets (23% crude proteins (CP) and 3050 kcal/kg metabolisable energy (ME))
At the end of the trial (day 42) 3 animals from each pen were randomly selected and slaughtered by cervical Revue Méd. Vét., 2013, 164, 4, 219-224
Effects of dietary boric acid supplementation on performance in broilers
BW (g) Day 0 Day 7 Day 14 Day 21 Day 28 Day 35 Day 42 BWG (g) BWG0-7 BWG7-14 BWG14-21 cBWG0-21 BWG21-28 BWG28-35 BWG35-42 cBWG21-42 cBWG0-42 FI (g) FI0-7 FI7-14 FI14-21 cFI0-21 FI21-28 FI28-35 FI35-42 cFI21-42 cFI0-42 FCR (g/g) FCR0-7 FCR7-14 FCR14-21 cFCR0-21 FCR21-28 FCR28-35 FCR35-42 cFCR21-42 cFCR0-42
221
Control
T1
T2
T3
p
43.1 ± 0.8 138.1 ± 4.1 355.6 ± 10.4 815.2 ± 19.1 1404.8 ± 30.1 1898.9 ± 64.0 2557.1 ± 69.7
43.3 ± 0.5 137.0 ± 4.0 366.5 ± 10.0 821.7 ± 22.4 1405.7 ± 33.1 2040.0 ± 48.1 2590.9 ± 60.1
43.5 ± 0.8 143.1 ± 5.0 361.5 ± 11.3 809.0 ± 21.0 1416.9 ± 30.8 2031.0 ± 47.4 2499.6 ± 71.2
43.1 ± 0.7 140.1 ± 6.9 354.8 ± 15.9 805.7 ± 29.9 1387.7 ± 37.9 1991.4 ± 44.1 2581.8 ± 42.0
NS NS NS NS NS NS NS
95.7 ± 8.0 215.9 ± 7.9 459.2 ± 7.1 770.8 ± 21.2 590.5 ± 24.8 509.2 ± 116.2 651.1 ± 52.2 1750.8 ± 92.9 2521.5 ± 99.2
93.8 ± 7.3 229.8 ± 6.1 457.6 ± 26.6 781.2 ± 31.7 586.9 ± 32.6 639.5 ± 45.6 552.1 ± 21.8 1778.5 ± 97.0 2559.7 ± 128.1
99.7 ± 6.1 218.4 ± 11.2 447.4 ± 13.4 765.5 ± 28.1 607.9 ± 23.6 614.2 ± 53.1 468.5 ± 77.1 1690.3 ± 147.4 2456.1 ± 168.1
92.1 ± 18.2 208.1 ± 24.2 440.6 ± 38.5 740.7 ± 80.5 577.6 ± 23.3 601.9 ± 27.4 594.3 ± 22.0 1773.8 ± 22.5 2514.5 ± 90.4
NS NS NS NS NS NS NS NS NS
127.0 ± 5.1 296.9 ± 10.9 671.5 ± 15.2 1095.4 ± 24.8 856.5 ± 28.8ab 1142.4 ± 105.9 1144.0 ± 38.2 3142.9 ± 89.9 4238.3 ± 111.3
107.6 ± 7.4 308.3 ± 15.8 641.8 ± 36.1 1057.7 ± 54.5 621.7 ± 21.3c 1133.8 ± 43.7 1185.2 ± 18.3 2980.4 ± 104.9 4038.0 ± 155.9
143.6 ± 5.3 340.8 ± 18.3 692.7 ± 45.5 1177.1 ± 42.5 722.5 ± 68.3bc 1099.4 ± 54.1 1111.3 ± 61.9 2933.1 ± 170.8 4110.2 ± 198.2
129.4 ± 20.4 295.6 ± 33.3 750.1 ± 68.0 1175.1 ± 118.4 985.5 ± 86.0a 1065.9 ± 53.6 1311.5 ± 97.7 3269.5 ± 48.4 4444.7 ± 104.9
NS NS NS NS < 0.01 NS NS NS NS
1.35 ± 0.12 1.38 ± 0.03 1.46 ± 0.04 1.42 ± 0.04 1.46 ± 0.06ab 2.72 ± 0.72 1.80 ± 0.20 1.80 ± 0.05 1.68 ± 0.03
1.15 ± 0.03 1.34 ± 0.05 1.41 ± 0.05 1.35 ± 0.03 1.13 ± 0.03b 1.79 ± 0.06 2.15 ± 0.07 1.68 ± 0.04 1.58 ± 0.03
1.46 ± 0.10 1.57 ± 0.09 1.55 ± 0.11 1.55 ± 0.09 1.19 ± 0.12b 1.81 ± 0.08 2.57 ± 0.41 1.76 ± 0.09 1.69 ± 0.08
1.54 ± 0.26 1.43 ± 0.04 1.71 ± 0.08 1.60 ± 0.08 1.55 ± 0.05a 1.78 ± 0.10 2.20 ± 0.11 1.84 ± 0.03 1.77 ± 0.04
NS NS NS NS < 0.01 NS NS NS NS
BW: body weight; BWG: body weight gain; BWGi-i+1: body weight gain calculated weekly; cBWG0-i: cumulated body weight gain calculated for a period of i days; FI: Food intake; FIi-i+1: Food intake measured weekly; cFI0-i: cumulated food intake determined for a period of i days; FCR: Food conversion ratio; FCRi-i+1: Food conversion ratio measured weekly; cFCR0-i: cumulated food conversion ratio determined for a period of i days; NS: not significant. Table II: Effects of the dietary boric acid supplementation (60 mg/kg) in different rearing periods (during the starting period, group T1; during the finishing period, group T2 and during the 2 periods, group T3) on performance (weights and weight gains, food intakes and food efficiency) in broiler chickens. Results are expressed as mean ± standard deviation.
dislocation for determined some carcass characteristics. Animals were individually weighed just prior slaughtering for determining the hot carcass weights and yields and also the absolute and relative weights of some visceral organs (heart, liver, spleen, gizzard, bursa of Fabricius). Blood samples (5 mL) were obtained from each bird by the jugular vein while animals were slaughtered. These samples were allowed to clot at room temperature for 6 hours and then they were centrifuged at 1500 g for 10 minutes at room temperature. Sera were carefully harvested and stored at -20°C until analysis. Serum cholesterol concentrations were detected spectrophotometrically with a commercial kit (Teco Diagnostic, 1286 Anaheim, CA 92807). Boron concentrations in serum and feed were also determined by ion chromatography (ICS) (Dionex 3000, USA).
while Ca and P contents were spectrophotometrically detected. For this purpose, the left tibia was removed and cleaned of adhering tissue; fat was removed by extraction with ether and alcohol and dried, and ash content determined on pooled samples of all bones from each pen as described by the Association of Official Analytical Chemists [1].
Left tibias were collected for each of slaughtered animal in order to determine bone ash contents using oven 610˚C,
It was summarized in Table II that body weights (BW) and body weight gains (BWG) showed no significant
Revue Méd. Vét., 2013, 164, 4, 219-224
Statistical analysis All data were analyzed by ANOVA using SPSS 11.50 program (Inc., Chicago, II, USA). Significant differences among treatment were determined using Duncan’s multiple range tests with a 5% level of probability.
Results
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YILDIZ (G.) AND COLLABORATORS Control
T1
T2
T3
p
Slaughter weight (g) Carcass weight (g) Carcass yield (%)
2435.4 ± 68.7 1810.3 ± 54.8 74.29 ± 0.37
2588.3 ± 56.3 1926.5 ± 46.5 74.41 ± 0.53
2438.3 ± 79.3 1807.5 ± 59.4 74.12 ± 0.41
2497.1 ± 75.7 1863.2 ± 41.4 74.58 ± 0.69
NS NS NS
Liver weight (g) Liver yield (%) Heart weight (g) Heart yield (%) Spleen weight (g) Spleen yield (%) Bursa weight (g) Bursa yield (%)
48.18 ± 1.28 1.98 ± 0.05 13.43 ± 0.58 0.55 ± 0.02 3.28 ± 0.17 0.14 ± 0.01 4.89 ± 0.55 0.20 ± 0.02
53.37 ± 2.14 2.06 ± 0.08 14.93 ± 0.81 0.58 ± 0.03 3.74 ± 0.40 0.14 ± 0.01 3.96 ± 0.36 0.16 ± 0.01
50.06 ± 1.73 2.07 ± 0.07 13.14 ± 0.51 0.54 ± 0.02 3.45 ± 0.44 0.14 ± 0.01 3.84 ± 0.57 0.16 ± 0.02
49.76 ± 1.10 1.99 ± 0.05 13.07 ± 0.48 0.52 ± 0.02 3.59 ± 0.46 0.14 ± 0.02 3.93 ± 0.34 0.16 ± 0.01
NS NS NS NS NS NS NS NS
Organ yield was calculated by the following formula: 100 x organ weight / carcass weight. NS: not significant.
Table III: Effects of the dietary boric acid supplementation (60 mg/kg) in different rearing periods (during the starting period, group T1; during the finishing period, group T2 and during the 2 periods, group T3) on carcass traits and visceral organ weights in broiler chickens. Results are expressed as mean ± standard deviation.
Cholesterol (mmol/L) Crude ash (%) Calcium (%) Phosphorus (%)
Control
T1
T2
T3
p
2.63 ± 0.34
2.40 ± 0.23
3.06 ± 0.30
2.22 ± 0.22
NS
58.07 ± 0.54 19.43 ± 0.23a 10.55 ± 0.08b
58.00 ± 0.51 21.18 ± 0.28b 10.65 ± 0.08b
58.33 ± 0.33 21.59 ± 0.30b 10.76 ± 0.06c
57.88 ± 0.67 20.00 ± 0.27a 10.29 ± 0.09a
NS < 0.001 < 0.01
Organ yield was calculated by the following formula: 100 x organ weight / carcass weight. Different superscripts in the same raw indicate significant differences between treatment groups (p < 0.05 or more). Table IV: Effects of the dietary boric acid supplementation (60 mg/kg) in different rearing periods (during the starting period, group T1; during the finishing period, group T2 and during the 2 periods, group T3) on serum cholesterol concentrations and tibia crude ash, calcium, and phosphorus contents in broiler chickens. Results are expressed as mean ± standard deviation.
differences between all treatment and control groups at any period of the trial in Table II. Similarly, food intake and food efficiency (Table II) were also not altered between groups with boron addition considering the whole trial period. But, at the 4th week, significantly decreases in food intake and food efficiency were noticed in groups supplemented with boron during the starting period (T1) or the finishing period (T2) compared to the other groups (p 0.05). At the end of the whole trial, although there were no significant differences in serum cholesterol concentrations between control and boron supplemented groups (Table IV), this parameter was slightly decreased in birds supplemented with boron during the starting period (groups T1 and T3) compared to the controls by approximately 8.7% (group T1) and 18.5% (group T3) whereas it was increased in birds treated for the finishing period (group T2) compared to
the control, T1 and T3 groups by 16%, 27.5% and 37.8%, respectively. In addition, the tibia crude ash proportions have not significantly differed between groups (Table IV) but the B addition to broiler diets has induced significant increases in tibia Ca content in broilers when it was performed for the starting period (group T1) or for the finishing period (group T2) compared to the control and the T3 groups (p < 0.001), and significant reduction in P content in birds supplemented for the whole period (p < 0.01) (Table IV).
Discussion In the present study, boric acid (60 mg/kg) addition to broiler diets in different time periods of rearing showed no statistically significant differences in performance and in blood cholesterol concentrations. The result about growth performance of the present trial was inharmonious with a previous experiment in which it was observed that boron supplementation has not only improved the growth parameters but also increased food efficiency [2]. Similarly, KURTOGLU et al. [13] pointed out that 5 and 25 mg/kg B addition to diets containing inadequate vitamin D3 caused a significant increase in body weight on days 14 and 28 compared to the inadequate D3 diet not supplemented with Revue Méd. Vét., 2013, 164, 4, 219-224
Effects of dietary boric acid supplementation on performance in broilers B. However, differences in body weights on day 45 between groups were not statistically significant. In the same way, the same researchers have not observed any effect on growth in laying hens supplemented with boron (50 to 200 mg/kg) for 120 days [14]. Additionally, ELIOT and EDWARDS [5] stated that the body weight gains were not affected in male broilers fed with diets containing 0, 20, 40, 80 mg/kg B. By contrast, Fassani et al. [8] reported that the body weight significantly increased in broilers dietary supplemented with 37.4 mg/kg for the first 21 days of experiment as well as in birds supplemented with 57 mg/kg boron during the whole experimental period but they reported no effects on food intake (FI) and food conversion ratio (FCR) as in the present study or as reported by ROSSI et al. [25] in broilers dietary supplemented with 5 mg/kg boron. On the other hand, KURTOGLU et al. [13] have observed FCR improvement in B supplemented broilers. The discrepancies observed among the different studies may be related to the use of various boron sources or environmental experimental conditions. However, it should be noticed in the present study that the weights of some internal organs (liver, heart and spleen) were numerically higher in birds supplemented with boron for the starting period whereas the weight of Fabricius Bursa was diminished by 25%. This result also confirmed previous report from YILDIZ et al. [28] who pointed out that dietary boric acid and yeast had no significant effect on visceral organ weights in broiler chickens. The dietary 60 mg/kg boron addition might help to enhance the immune system for the first 3 weeks age of broilers but further studies are required for exploring this point. In the present study, no significant variations in cholesterolemia were evidenced between groups although some numerical alterations were found (the lowest values were obtained in birds supplemented with boron for the whole experimental period). Similarly, EKLIN et al. [4] observed that the boron addition had no significant effects on cholesterol concentrations in laying hens. On the other hand, EREN et al. [6] and EREN and UYANIK [7] reported that serum cholesterol concentrations decreased by increasing dietary B contents in quails (B: 0 to 240 mg/kg) and in laying hens (B: 0 to 400 mg/kg), respectively. On the other hand, tibia calcium and phosphorus contents were significantly altered in boron supplemented broilers: significantly higher Ca contents were found in birds supplemented during the starting (group T1) or the finishing period (group T2) compared to the control group (p < 0.001) whereas birds supplemented for the whole experiment period (group T3) showed significantly lower P contents (p < 0.01). According to our results, the highest Ca and P contents were observed in the group T2 and were increased by 11% and 2% respectively, compared to the mineral contents determined in the control group. MIZRAK et al. [15] reported that dietary 30 ppm boron addition resulted in increasing bone ash, Ca and P contents compared to the control and the other treatment groups. KURTOGLU et al. Revue Méd. Vét., 2013, 164, 4, 219-224
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[14] have also observed that dietary boron supplementation for 120 days in laying hens induced a significant decrease in damaged egg ratios and a significant increase in calcaemia. In laying hens supplemented with boron (60 to 240 mg/kg) alone or in combination with copper (75 to 300 mg/kg) for 16 weeks, OLGUN et al. [24] have also evidenced positive effects on bone resistance and trace elements (B, Cu and Zn) distribution in the organism coupled to Ca, P and Mg sparing in bones. As a conclusion, dietary 60 mg/kg B addition has exhibited no negative effects on growth performance, serum cholesterol concentrations or carcass characteristics in broiler chickens whereas tibia contents of Ca (p < 0.001) and P at a lesser extend were increased in birds treated for the starting or (exclusive) finishing periods. Consequently, dietary B addition may be useful for leg health of broiler chickens which is very important point in poultry industry. However, these results should be confirmed by further intensive investigations on bone mineral composition in broilers fed with diets with various boron sources and dosages during different rearing periods.
Acknowledgements Some part of this research has been presented as a poster presentation in V. National Animal Nutrition Congress, 2009, Tekirdag, Turkey. This research (Project No: 2003K120190) was supported by T.R. Prime Ministry State Planning Organization (DTP).
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