SciELO - Scientific Electronic Library Online

 
vol.47Antioxidant effect of the guava byproduct in the diet of broilers in the starter phaseGlycemic control in minks with tendency to obesity in the perinatal period with the use of HbA1C índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Journal

Artigo

Indicadores

Links relacionados

Compartilhar


Revista Brasileira de Zootecnia

versão impressa ISSN 1516-3598versão On-line ISSN 1806-9290

R. Bras. Zootec. vol.47  Viçosa  2018  Epub 23-Abr-2018

https://doi.org/10.1590/rbz4720170186 

Non-ruminants

Effects of 1,25-dihydroxycholecalciferol and reduced vitamin D3 level on broiler performance and bone quality

Fernanda Lima de Souza Castro1  * 

Nelson Carneiro Baião1 

Roselene Ecco2 

Mário Jefferson Quirino Louzada3 

Érica de Faria Melo1 

Mariana Masseo Saldanha1 

Marcela Viana Triginelli1 

Leonardo José Camargos Lara1 

1Universidade Federal de Minas Gerais, Escola de Veterinária, Departamento de Zootecnia, Belo Horizonte, MG, Brasil.

2Universidade Federal de Minas Gerais, Escola de Veterinária, Departamento de Clínica e Cirurgia Veterinárias, Belo Horizonte, MG, Brasil.

3Universidade Estadual Paulista, Faculdade de Medicina Veterinária, Departamento de Apoio, Produção e Saúde Animal, Araçatuba, SP, Brasil.


ABSTRACT

This study was conducted to evaluate the effect of two levels of vitamin D3 with or without 1,25- dihydroxycholecalciferol (1,25(OH)2D3) on live performance and bone quality of broiler chickens. For that, we used a completely randomized design in a 2 × 2 factorial arrangement, with eight replicates of 30 Cobb®500 male broiler chicks each (n = 960). The two levels of vitamin D3 and the addition or not of 0.5 μg 1,25(OH)2D3/kg were considered as main factors. The vitamin D3 levels were: 2500/2000 IU/kg and 1250/1000 IU/kg for the starter (1 to 21 days) and grower (22 to 40 days) phases, respectively, with the first representing the levels used in industry (100%) and the second, a reduction in 50% of those levels. The 1,25(OH)2D3 source was Solanum glaucophyllum. On days 21 and 40, one broiler per replicate was killed and long bones were removed for analyses of mineral percentage, bone mineral density, biomechanical properties, and morphology. No significant differences were found related to vitamin D3 levels and the addition or not of 1,25(OH)2D3 for live performance, mineral percentage, strength, stiffness, and morphology. Toughness was lower when 1,25(OH)2D3 was used at 21 days, but this effect was not observed at 40 days of age. Bone mineral density was greater when 100% of vitamin D3 was used at 40 days of age. The reduction of up to 50% of vitamin D3 levels is sufficient to ensure performance and bone development of broilers at 21 and 40 days of age. The inclusion of 0.5 μg 1,25(OH)2D3/kg in addition to diets with sufficient levels of vitamin D3 shows no effect on the improvement of those parameters at the same ages.

Key Words broilers; growth performance; Solanum glaucophyllum

Introduction

To fulfill the growing demand for food, the use of highly specialized broilers with genetic potential for growth has increased. The rapid muscle development is not followed by adequate bone support, which remain immature, burdening the locomotor system. As a result, there is an increase in mortality and fractures due to bone fragility and reduction in welfare, leading to significant economic losses (Silva et al., 2001; Araujo et al., 2012). The formulation of specific diets using vitamin D and its metabolites has been shown as an alternative to reduce these problems.

The vitamin D content available in raw materials used in diets is usually ignored during formulation, and the need for this vitamin is supplied by adding vitamin supplements. As vitamin D2 (ergocalciferol) potency is about 10 times lower than vitamin D3 (cholecalciferol) for poultry, the last one is often used. To reach its main metabolically active form, 1,25-dihydroxycholecalciferol (1,25(OH)2D3), vitamin D3 must be hydroxylated first in the liver into 25-hydroxycholecalciferol (25(OH)D3), then in the kidneys (Souza and Vieites, 2014). 1,25(OH)2D3 has an important role in calcium and phosphorus homeostasis, bone growth and remodeling, and in the immune system (Kochupillai, 2008; Muszkat et al., 2010).

According to NRC and Cobb® 500 manual, the recommended vitamin D3 levels for poultry are 200 and 5000 IU/kg, respectively (NRC, 1994; Cobb, 2015). The deficiency or imbalance of vitamins and minerals is associated with the development of skeletal disorders, such as rickets (Klasing, 2013). However, the companies have been working with a safety margin of about five to ten times higher than the actual need, using supplementation as a preventative tool. The excess of vitamin D can be toxic to tissues by inducing the mineralization of soft tissues, has negative effect on leg health, decreases body weight gain, and increases feed cost (Cruickshank and Sim, 1987; Zanuzzi et al., 2012).

The supplementation with different metabolites and sources of vitamin D3 is a method for maximizing animal performance. The use of metabolites may reduce the energy expenditure, since they are in an advanced form, thus, more available for immediate utilization (Garcia et al., 2013).

The objective was to evaluate the effects of two vitamin D3 levels with or without 1,25(OH)2D3 supplementation in diets on live performance and bone development of broilers grown under conditions simulating commercial poultry production.

Material and Methods

The experiment was conducted in Igarapé, Brazil (20°04'13”S and 44°18'06” W), under approval of the Ethical Principles in Animal Experimentation Committee (case no. 225/2014).

The experimental design was completely randomized, consisting of a 2 × 2 factorial arrangement: the presence or absence of 1,25(OH)2D3 and two different dietary levels of vitamin D3, eight replicates, and 30 birds per experimental unit.

One-day-old Cobb® 500 male chicks (n = 960) were obtained from a local hatchery and assigned to floor pens in a poultry house of commercial and experimental design with curtain sidewalls. Thirty chicks were randomly allocated to each of the 32 identical pens (14 birds/m2). Wood shavings were used as bedding, and each pen was equipped with an automatic water fountain and a tube-type feeder, providing ad libitum access to feed and water throughout the study. The light program was 24 h of light in the first 14 days and natural light after this period.

The diets were based on corn and soybean meal and formulated for starter (1 to 21 days) and grower (22 to 40 days) phases. The diets were formulated considering the nutritional values of the raw materials according to Brazilian tables for poultry and swine (Rostagno et al., 2011) (Table 1).

Table 1 Composition of diets for all phases (1-40 days, as-fed basis; g kg -1

Item Starter (1 to 21 days)1 * Grower (22 to 40 days)2 **
Ingredient
Yellow corn 573.40 573.40 630.00 630.00
Soybean meal (45% crude protein) 350.00 350.00 291.90 291.70
Meat and bone meal (40% crude protein) 36.70 36.70 21.60 21.60
Soybean oil 22.50 22.50 36.60 36.60
Limestone 5.50 5.50 6.60 6.60
Salt 3.90 3.95 4.20 4.25
DL-methionine (98%) 3.20 3.20 3.10 3.10
Vitamin and mineral premix* 2.00 2.00 2.00 2.00
L-lysine HCl (98%) 1.80 1.70 2.70 2.80
Choline chloride (60%) 0.60 0.60 0.50 0.50
L-threonine 0.40 0.40 0.80 0.80
Solanum glaucophyllum (1,25(OH)2D3) 0.05 0.05
Nutrient levels
Metabolizable energy (kcal/kg) 2,997 2,997 3,152 3,152
Crude protein (g/kg) 225.35 225.35 197.92 197.92
Ether extract (g/kg) 53.19 53.19 66.40 66.40
Calcium (g/kg) 9.32 9.32 7.64 7.64
Total P (g/kg) 7.00 7.00 5.80 5.80
Nonphytate P (g/kg) 4.67 4.67 3.63 3.63
Sodium (g/kg) 2.03 2.03 1.99 1.99
Lysine (g/kg) 12.11 12.11 11.29 11.29
Methionine (g/kg) 6.07 6.07 5.67 5.67
Methionine + cystine (g/kg) 8.99 8.99 8.29 8.29
Threonine (g/kg) 7.91 7.91 7.29 7.29
Tryptophan (g/kg) 2.37 2.37 2.03 2.03

*Mineral and vitamin premix (starter period) provided per kg of diet: vitamin A, 9,000 UI; vitamin E, 14 mg; vitamin K3, 2 mg; vitamin B1 2.5 mg; vitamin B2, 6.2 mg; vitamin Вб, 4 mg; vitamin B12, 14 mcg; nicotinic acid, 40 mg; folic acid, 1 mg; pantothenic acid, 15 mg; Se, 0.2 mg; I, 1.2 mg; Fe, 50 mg; Cu, 10 mg; Mn, 80 mg; Zn, 60 mg; Finase, 500 FTU; Halquinol, 0.03 g; MNGrow, 0.5 g; BHT, 0.1 g.

**Mineral and vitamin premix (grower period) provided per kg of diet: vitamin A, 7,000 UI; vitamin E, 11 mg; vitamin K3, 1.6 mg; vitamin B1, 1.6 mg; vitamin B2, 4.5 mg; vitamin B6, 2.2 mg; vitamin B12, 10 mcg; nicotinic acid, 32 mg; folic acid, 0.8 mg; pantothenic acid, 12 mg; Se 0.2, mg; I, 1.2 mg; Fe, 50 mg; Cu, 10 mg; Mn, 80 mg; Z, 60 mg; Finase, 500 FTU; Halquinol 0.03 g; Salynomicin, 0.066 g; BHT, 0.1 g.

1Vitamin D3: 2500 (100%) and 1250 (50%) μg/kg.

2Vitamin D3: 2000 (100%) and 1000 (50%) μg/kg.

The vitamin D3 was provided by two different vitamin supplements, which were the only sources of vitamin D3 considered during feed formulation. The vitamin supplements contained: 2500 and 2000 IU vitamin D3/kg of feed for starter and grower phases, respectively (100% according to commercial levels), and 1250 and 1000 IU vitamin D3/kg of feed for starter and grower phases, respectively (reduction of 50%). The 1,25(OH)2D3 source was a commercial product obtained from dried leaves of Solanum glaucophyllum (SG) (10 ppm). The inclusion was of 50 g/ton of feed according to manufacturer's recommendations, resulting in an addition of 0.5 μg 1,25(OH)2D3/kg of feed in a glycosidic form. The presence of metabolite in the plant extract and its activity were characterized by Napoli et al. (1977), Gil et al. (2006), and Bachmann et al. (2013).

Birds and feed were weighed weekly throughout the experimental period to assess performance (average daily feed intake, average daily gain, and feed conversion ratio). These data were used to calculate the accumulated values at 21 and 40 days of the experiment. Mortality was checked daily and used to adjust feed conversion ratio, obtained by average daily feed intake:average daily gain.

At 21 and 40 days, one bird per pen, selected from a range of mean body weight ± 10%, was killed by cervical dislocation. The right and left femora and left and right tibiotarsi were removed, dissected, and cleaned of any adhering tissue. For gross evaluation of long bones, the left femora and right tibiotarsi were sectioned longitudinally to reveal the growth plates (hypertrophy and proliferation zones). This technique allowed the visual evaluation of the cortex thickness and the amount and density of trabecular bone and cartilage in metaphyseal and epiphyseal regions. The right femora were analyzed for ash, calcium, and phosphorus percentage determination on dry fat-free bones, as described by AOAC (1995). The left tibiotarsi were first subjected to the optical densitometry (g/cm2) analysis using the DPX-ALPHA densitometer model to determine bone mineral density (BMD). Later, they were subjected to a biomechanical assay using a universal machine EMIC® DL 300 model, in a three-point destructive bending test, with a 2000N load cell. The software Instron Series IX recorded the values of breaking strength (determined by maximum load), stiffness, and toughness.

The pen means were the experimental units for broiler performance data and broiler was the experimental unit for the bone parameter data. The means were subjected to ANOVA as a factorial arrangement of treatments with dietary vitamin D3 levels and presence or absence of 1,25(OH)2D3 as the main effects. All possible interaction among and between the main effects were evaluated using the general linear model procedure of SAS software (Statistical Analysis System, version 9.0). Statements of significance were based on P≤0.05.

Results

There was no interaction of dietary vitamin D3 levels with presence or absence of 1,25(OH)2D3 (P>0.05) for the performance variables. At 21 and 40 days, the average daily feed intake, average daily gain, and feed conversion ratio were not influenced by the level or additional source of vitamin D3 (P>0.05) (Table 2).

Table 2 Effect of 1,25(OH)2D3 and vitamin D3 levels on broiler average daily feed intake (ADFI), average daily weight gain (ADG), and feed conversion ratio (FCR) at 21 and 40 days of age 

Age (days)
1-21 days 1-40 days
ADFI (g) ADG (g) FCR (g/g) ADFI (g) ADG (g) FCR (g/g)
Vitamin D3 1,25(ОН)2D3
100% vitamin D31 0.0 μg/kg 62.12 47.87 1.298 117.50 77.00 1.524
0.5 μg/kg 62.50 48.75 1.286 120.25 80.00 1.506
50% vitamin D32 0.0 μg/kg 61.50 47.50 1.294 118.25 78.12 1.515
0.5 μg/kg 62.50 47.75 1.307 119.25 77.50 1.535
Vitamin D3
100% vitamin D3 62.31 48.31 1.292 118.87 78.50 1.515
50% vitamin D3 62.00 47.62 1.300 118.75 77.81 1.525
1,25(OH)2D3
0.0 μg/kg 61.81 47.68 1.296 117.87 77.56 1.519
0.5 μg/kg 62.50 48.25 1.296 119.75 78.75 1.520
P-value
Vitamin D3 0.631 0.279 0.214 0.808 0.447 0.321
1,25(OH)2D3 0.331 0.322 0.950 0.084 0.170 0.919
Interaction 0.657 0.681 0.059 0.436 0.102 0.062
Standard error 0.0003 0.0002 0.0034 0.0005 0.0004 0.0051

1100% vitamin D3 corresponds to 2500 and 2000 IU/kg for starter and grower phases, respectively.

250% vitamin D3 corresponds to 1250 and 1000 IU/kg for starter and grower phases, respectively.

Significant by F test (P≤0.05).

Mortality during the present study was not significantly affected by level of vitamin D3 or inclusion of the metabolite, with no interaction between the levels and presence or absence of 1,25(OH)2D3 (P>0.05) (data not shown).

There was no interaction of dietary vitamin D3 levels with presence or absence of 1,25(OH)2D3 for ash, calcium, and phosphorus content at 21 and 40 days (P>0.05) (Table 3). The mineral content was similar between the treatments at the two ages (P>0.05).

Table 3 Effect of 1,25(OH)2D3 and vitamin D3 levels on bone ash (Ash), calcium (Ca), and phosphorus (P) at 21 and 40 days of age 

Age (days)
1-21 days 1-40 days
Ash (%) Ca (%) P (%) Ash (%) Ca (%) P (%)
Vitamin D3 1,25(ОН)2D3
100% vitamin D31 0.0 μg/kg 43.63 16.61 7.21 43.73 15.27 6.66
0.5 μg/kg 43.76 16.85 6.99 42.81 15.50 6.86
50% vitamin D32 0.0 μg/kg 43.82 16.34 6.86 43.10 15.06 6.88
0.5 μg/kg 42.66 16.95 7.14 40.80 14.80 6.94
Vitamin D3
100% vitamin D3 43.69 16.73 7.10 43.27 15.38 6.76
50% vitamin D3 43.24 16.65 7.00 42.00 14.94 6.91
1,25(ОН)2D3
0.0 μg/kg 43.72 16.48 7.03 43.41 15.17 6.77
0.5 μg/kg 43.21 16.90 7.07 41.87 15.17 6.90
P- value
Vitamin D3 0.567 0.779 0.643 0.304 0.072 0.460
1,25(ОН)2D3 0.516 0.169 0.883 0.193 0.945 0.534
Interaction 0.413 0.539 0.240 0.565 0.307 0.729
Standard error 0.3800 0.1477 0.1047 0.5959 0.1239 0.0987

1100% vitamin D3 corresponds to 2500 and 2000 IU/kg for starter and grower phases, respectively.

250% vitamin D3 corresponds to 1250 and 1000 IU/kg for starter and grower phases, respectively.

Significant by F test (P≤0.05).

There was no interaction of dietary vitamin D3 levels with or without the use of 1,25(OH)2D3 for breaking strength, stiffness, and toughness at 21 and 40 days neither for BMD at 40 days of age (P>0.05) (Table 4). Breaking strength and stiffness were similar between the treatments at 21 and 40 days (P>0.05). Toughness was influenced by 1,25(OH)2D3 at 21 days (P≤0.05). When the metabolite was used, toughness was lower than when the metabolite was not used; however, this difference was not observed at 40 days (P>0.05). Bone mineral density was not influenced by the addition or not of 1,25(OH)2D3 at 40 days of age; however, this trait was affected by the vitamin D3 levels. The use of 100% of vitamin D3 resulted in greater BMD when compared with 50% of vitamin D3 (P≤0.05).

Table 4 Effect of 1,25(OH)2D3 and vitamin D3 levels on maximum load (ML), stiffness (S), and toughness (T) at 21 and 40 days of age and bone mineral density (BMD) at 40 days of age 

Age (days)
1-21 days 1-40 days
ML (N) S (N/mm) T (mJ) ML (N) S (N/mm) T (mJ) BMD (g/cm2)
Vitamin D3 1,25(ОН)2D3
100% vitamin D31 0.0 μg/kg 201.30 106.65 339.87 336.48 163.96 768.00 0.085
0.5 μg/kg 194.16 119.83 293.50 409.07 179.66 738.75 0.099
50% vitamin D32 0.0 μg/kg 204.80 105.92 368.15 375.13 173.02 843.37 0.075
0.5 μg/kg 181.08 115.81 285.00 394.36 177.53 803.62 0.077
Vitamin D3
100% vitamin D3 197.73 113.24 326.56 372.78 171.81 753.38 0.093a
50% vitamin D3 192.94 110.86 316.69 384.75 175.28 823.50 0.076b
1,25(OH)2D3
0.0 μg/kg 203.05 106.29 354.00a 355.81 168.49 805.69 0.080
0.5 μg/kg 187.62 117.82 289.25b 401.72 178.60 771.19 0.088
P-value
Vitamin D3 0.611 0.755 0.649 0.640 0.777 0.243 0.020*
1,25(ОН)2D3 0.108 0.138 0.005* 0.080 0.412 0.562 0.249
Interaction 0.381 0.829 0.399 0.301 0.648 0.929 0.404
Standard error 4.7174 3.7511 11.8958 12.9960 5.8737 28.8231 0.0037

1100% vitamin D3 corresponds to 2500 and 2000 Ul/kg for starter and grower phases, respectively.

250% vitamin D3 corresponds to 1250 and 1000 Ul/kg for starter and grower phases, respectively.

*Significant by F test (P≤0.05).

a,bValues within a column with different letters differ significantly by F test (P≤0.05).

During the gross evaluation of tibiotarsi of broilers at 21 and 40 days, the growth plates in all treatments were regular, with similar thickness, blood vessels, and trabecular bone well distributed, and without the presence of any avascular cartilage plug, which indicates absence of disease (data not shown).

Discussion

The vitamin D3 deficiency can result in reduction in feed intake and lead to abnormal body development (Andriguetto et al., 2002). This fact was not observed in the present study, which indicates that the reduction in 50% of the vitamin D3 level, regardless of the addition of 1,25(OH)2D3, provides the necessary amount of this vitamin for a normal performance of broilers. The body weights found in the present study, for all treatments, were greater than the ones determined by Cobb (2015), of 971 and 2832 g at 21 and 40 days of age, respectively.

These results are contrary to the ones found by Souza et al. (2013). The authors evaluated the performance of broilers supplemented with 1,25(OH)2D3 levels ranging from 0 to 5 μg/kg, reducing in 20% the levels of available calcium and phosphorus. Feed intake was not influenced by the treatments. However, there was a significant improvement in weight gain and feed conversion ratio when broilers were fed 1 and 2 μg 1,25(OH)2D3/kg at 42 days.

The results found in the present study are in accordance with Alves (2014). The author compared a control group (100% of vitamin D3 in premix without 1,25(OH)2D3) to different levels of vitamin D3 in premix supplemented with the same quantity of 1,25(OH)2D3. Phosphorus and calcium levels were balanced for all treatments. The reduction in 50% of the vitamin level, with the addition of 1,25(OH)2D3, did not differ from the control group for any of the performance parameters at 21 and 42 days.

Likewise, Vieites et al. (2014) studied the inclusion of different levels of 1,25(OH)2D3 (ranging from 0 to 2.5 μg/kg), with calcium and phosphorus levels fixed. The authors concluded that the supplementation with up to 2μg 1,25(OH)2D3/kg did not influence performance parameters of broilers at 8 and 42 days.

Those studies, as well as the present research, are in accordance with findings related to vitamin D3 and balanced mineral levels. These findings show that when calcium and phosphorus levels are adequate, there are no direct effects of vitamin D3 supplementation on performance of broilers (Edwards Jr. et al., 2002). The addition of more than 12001600 IU of vitamin D3 per kg of feed has little response on these parameters (Baker et al., 1998).

The skeletal status of poultry and the effect of vitamin D on bones are traditionally assessed by histology, estimations of bone ash, calcium and phosphorus percentage, and bone breaking strength (Thorp and Waddington, 1997).

When there is a reduction in vitamin D3 levels and, consequently, imbalance in calcium and phosphorus plasmatic levels, a mobilization of these minerals is observed from the cortical bone to plasma, as a direct effect of parathyroid hormone (PTH). This response was not observed in the present study, since the bone mineral content, in all treatments, was not affected, reassuring that the reduction in 50% of the vitamin D3 levels was not severe. The addition of 1,25(OH)2D3 did not improve the mineral deposition in cortical bone.

Compatible findings were found by Alves (2014). The author observed that a reduction in 50% of the vitamin D3 level with addition of 1,25(OH)2D3 did not differ from the control group for bone ash and calcium content at 21 and 42 days.

Elliot et al. (1995) evaluated two calcium levels (1.00 and 0.65%) and 1,25(OH)2D3 (0 and 5μg/kg) in three-week-old broilers. Both 1.00% calcium and 5μg/kg 1,25(OH)2D3 increased bone ash at this age, which was not observed in the present study with the supplementation of 0μg 1,25(OH)2D3 and balanced calcium level. A dietary supplementation of a low Ca diet containing 980 IU vitamin D3/kg with 10μg 1,25(OH)2D3/kg may increase tibiae bone ash (Edwards Jr., 1989; Edwards Jr., 1990).

Bone mechanical properties are determined primarily by the amounts, arrangement, and molecular structure of collagen and mineral content. Strength and stiffness are closely related to mineralization of bone, which agrees with the present study, since there was no difference between treatments for mineral content and bone strength and stiffness. However, a highly mineralized bone, that is also stiff, will require less energy to fracture than a bone that is more capable of yielding (Turner, 2006).

On the other hand, toughness is mostly improved by collagen, which allows bones to bend without breaking, despite the rigidity provided by the minerals (Wang et al., 2002; Currey, 2003). This biomechanical property indicates the amount of energy needed to cause the material failure. Thus, a tough bone will be more resistant to fracture, even though it may be less resistant to yielding (Turner and Burr, 1993). In the present study, the reduction in toughness observed in animals treated with 0.5 μg/kg 1,25(OH)2D3 might indicate that these bones were less capable of bending, which could be explained by a reduction in the collagen content. According to Artaza and Norris (2009), the addition of 1,25(OH)2D3 in mesenchymal multipotent cell cultures downregulates the expression of collagen I and III; however, we did not measure collagen content to confirm it.

Bachmann et al. (2013) investigated the supplementation of a control diet containing 1000 IU vitamin D3/kg and imbalanced Ca:P, with a synthetic source of 1,25(OH)2D3 (2.5 μg/kg and 5 μg/kg), purified extract of Solanum glaucophyllum (9.5 μg/kg and 37.8 μg/kg), and dried Solanum glaucophyllum leaves (10 μg/kg). The authors did not find significant differences among the treatments for tibiae breaking strength and stiffness at 14 days. The present study also used dried Solanum glaucophyllum leaves source of 1,25(OH)2D3 and the inclusion of 0.5 μg/kg was not sufficient to improve these variables.

Bone mineral density is the mass of bone material, organic and inorganic, measured in an area (g/cm2) and depends on the absorption of radiation by the skeleton. Since the inorganic portion is the main component of extracellular bone matrix, BMD is a good indicative of bone mineralization. The measure of BMD through dualenergy x-ray absorptiometry (DEXA) is not largely used in animals, although it is considered a standard method for determination of osteoporosis in humans (Hailey et al., 1996; Silva, 2003).

In the present study, BMD at 40 days of age was greater when broilers received a diet with 100% of vitamin D3, suggesting that the use of this diet resulted in bones more capable of absorbing radiation, thus more mineralized, than the ones from animals treated with 50% of vitamin D3. However, despite of this result, the mineral content, stiffness, and breaking strength of all treatments were similar, indicating that the bones of animals fed 50% of vitamin D3 are as well developed as the bones of animals fed 100% of vitamin D3 at 40 days of age.

The histological evaluation of the bone growth plate is a method of histopathological diagnosis of bone diseases. When there is a disease in the locomotor system, it is possible to characterize a change in the thickness of the growth plate, a reduction in vascularization, and lower cell differentiation and organization (Thorp and Waddington, 1997).

The most characteristic change in vitamin D3 deficiency in chicks is the enlargement of the growth plate due to widening of the proliferating and hypertrophic zones. Probably, the deficiency causes delay of chondrocyte hypertrophy. When the deficiency progresses, there is increase of porosity in the cortical bone due to the reabsorption, determining decrease in the mechanical strength of long bones (Klasing, 2013). These changes were not found during the gross evaluation of tibiae and femora of broilers at 21 and 40 days. The growth plates, in all treatments, were regular, with similar thickness, blood vessels, and trabecular bone well distributed and without the presence of any avascular cartilage plug, which indicates absence of disease.

In the present study, the reduction in 50% of the vitamin D3 levels commonly used in commercial poultry production was not severe enough, which may explain why no differences were observed. These levels (1250 and 1000 IU/kg for starter and grower phases, respectively) in diets with balanced Ca and P were sufficient to ensure the maximum performance and bone development of broilers at 21 and 40 days.

Conclusions

The reduction up to 50% (1250 and 1000 IU/kg in the starter and grower phases, respectively) of vitamin D3 levels in diets with balanced Ca and P commonly used in commercial poultry production is sufficient to ensure the maximum performance of broilers at 21 and 40 days. The use of 0.5 μg 1,25(OH)2D3/kg, in a glyosidic form, in addition to sufficient levels of dietary vitamin D3 does not improve the parameters measured, even when 50% of vitamin D3 is used. These results support the claim that an unnecessary excess of vitamin D3 is used in commercial broiler production. Thus, the reduction in 50% of vitamin D3 levels used commercially, without supplementation with 1,25(OH)2D3, may represent an important decrease in production costs and row material waste, influencing the industries to narrow the safety margin.

Acknowledgments

The authors acknowledge Technofeed, the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), for the financial support, and Universidade Estadual Paulista (UNESP/Araçatuba), for the technical support.

References

Alves, O. S. Efeito dos niveis de vitamina D3 em premix e suplementação com 1,25(OH)2D3 na ração de frangos de corte. 2014. Dissertação (M.Sc.). Universidade Federal do Rio de Janeiro, Rio de Janeiro. [ Links ]

Andriguetto, J. M.; Perly, L.; Minardi, I.; Gemael, A.; Flemming, J. S.; Souza, G. A. and Bona Filho, A. 2002. As vitaminas na nutrição animal. p.140-143. In: Nutrição animal, as bases e os fundamentos da nutrição animal: os alimentos. Andriguetto, J. M., ed. Nobel, São Paulo. [ Links ]

Araújo, G. M.; Vieites, F. M. and Souza, C. S. 2012. Importância do desenvolvimento ósseo na avicultura. Archivos de Zootecnia 61:79-89. [ Links ]

Artaza, N. J. and Norris, K. C. 2009. Vitamin D reduces the expression of collagen and key profibrotic factors by inducing an antifibrotic phenotype in mesenchymal multipotent cells. Journal of Endocrinology 200:207-221. [ Links ]

AOAC - Association of Official Analytical Chemistry. 1995. Official methods of analysis. 16th ed. AOAC International, Arlington. [ Links ]

Bachmann, H.; Autzen, S.; Frey, U.; Wehr, U.; Rambeck, W.; McCormack, H. and Whitehead, C. C. 2013. The efficacy of a standardized product from dried leaves of Solanum glaucophyllum as source of 1,25-dihydroxycholecalciferol for poultry. British Poultry Science 54:642-652. [ Links ]

Baker, D. H.; Biehl, R. R. and Emmert, J. L. 1998. Vitamin D3 requirement of young chicks receiving diets varying in calcium and available phosphorus. British Poultry Science 39:413-417. [ Links ]

Cobb. 2015. Broiler performance & nutrition supplement, Cobb500™. Available at: <http://www.cobbvantress.com/docs/defaultsource/cobbguides/Cobb500_Broiler_Performance_And_Nutrition_Supplement.pdf>. Accessed on: July 11, 2016. [ Links ]

Cruickshank, J. J. and Sim, J. S. 1987. Effects of excess vitamin D3 and cage density on the incidence of leg abnormalities in broiler chickens. Avian Disease 31:332-338. [ Links ]

Currey, J. D. 2003. Role of collagen and other organics in the mechanical properties of bone. Osteoporosis International 14: S29-S36. [ Links ]

Edwards Jr, H. M. 1989. The effect of dietary cholecalciferol, 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol on the development of tibial dyschondroplasia in broiler chickens in the absence and presence of disulfiram. Journal of Nutrition 119:647-652. [ Links ]

Edwards Jr, H. M. 1990. Efficacy of several vitamin D compounds in the prevention of tibial dyschondroplasia in broiler chickens. Journal of Nutrition 120:1054-1061. [ Links ]

Edwards Jr, H. M.; Shirley, R. B.; Escoe, W. B. and Pesti, G. M. 2002. Quantitative evaluation of 1-a-hydroxycholecalciferol as a cholecalciferol substitute for broilers. Poultry Science 81:664-669. [ Links ]

Elliot, M. A.; Roberson, K. D.; Rowland, G. N. and Edwards Jr., H. M. 1995. Effects of dietary calcium and 1,25-dihydroxycholecalciferol on the development of tibial dyschondroplasia in broilers during the starter and grower periods. Poultry Science 74:1495-1505. [ Links ]

Garcia, A. F. Q. M.; Murakami, A. E.; Duarte, C. R. A.; Rojas, I. C. O.; Picoli, K. P. and Puzotti, M. M. 2013. Use of vitamin D3 and its metabolites in broiler chicken feed on performance, bone parameters and meat quality. Asian-Australasian Journal of Animal Sciences 26:408-415. [ Links ]

Gil, S.; Dallorso, M. and Horst, R. 2006. Screening of vitamin d activity (VDA) of Solanum glaucophyllum leaves measured by radioimmunoassay (RIA). The Journal of Steroid Biochemistry and Molecular Biology 103:483-486. [ Links ]

Hailey, D.; Sampietro-Colom, L.; Marshall, D.; Rico, R.; Granados, A. and Asua, J. 1996. The effectiveness of bone density measurement and associated treatments for prevention of fractures: An international collaboration review. International Journal of Technology Assessment in Heath Care 14:237-254. [ Links ]

Klasing, K. C. 2013. Nutritional diseases. p.1205-1232. In: Diseases of poultry. Swayne, D. E., ed. 13th ed. Wiley-Blackwell, New York. [ Links ]

Kochupillai, N. 2008. The physiology of vitamin D: current concepts. Indian Journal of Medical Research 127:256-262. [ Links ]

Muszkat, P.; Camargo, M. B. R.; Griz, L. H. M. and Lazaretti-Castro, M. 2010. Evidence-based non-skeletal actions of vitamin D. Arquivos Brasileiros de Endocrinología & Metabologia 54:110-117. [ Links ]

Napoli, J. L.; Reeve, L. E.; Eisman, J. A.; Schnoes, H. K. and DeLuca, H. F. 1977. Solanum glaucophyllum as source of 1,25- dihydroxyvitamin D3. The Journal of Biological Chemistry 252:2580-2583. [ Links ]

NRC - National Research Council. 1994. Nutrient requirements of poultry. 9th ed. The National Academies Press, Washington, DC. [ Links ]

Rostagno, H. S.; Albino, L. F. T.; Donzele, J. L.; Gomes, P. C.; Oliveira, R. F.; Lopes, D. C.; Ferreira, A. S.; Barreto, S. L. T. and Euclides, R. F. 2011. Brazilian tables for poultry and swine - Feed composition and nutritional requirements. 3.ed. UFV, Viçosa, MG, Brazil. [ Links ]

Silva, L. K. 2003. Avaliação tecnológica em saúde: densitometria óssea e terapêuticas alternativas na osteoporose pós menopausa. Caderno de Saúde Pública 19:987-1003. [ Links ]

Silva, F. A.; Moraes, G. H. K.; Rodrigues, A. C. P.; Oliveira, M. G. A.; Rostagno, H. S.; Albino, L. F. T.; Fonseca, C. C. and Minafra, C. S. 2001. Efeitos do ácido L-glutâmico e da vitamina D3 no desempenho e nas anomalias ósseas de pintos de corte. Revista Brasileira de Zootecnia 30:2059-2066. [ Links ]

Souza, C. S. and Vieites, F. M. 2014. Vitamin D3 e seus metabólitos para frangos de corte. Archivos de Zootecnia 63:11-24. [ Links ]

Souza, C. S.; Vieites, F. M.; Vasconcellos, C. H. F.; Calderano, A. A.; Nunes, R. V.; Ferreira, C. M.; Pereira, T. V. S. and Moraes, G. H. K. 2013. Suplemento de 1,25 dihidroxicolecalciferol e redução de cálcio e fósforo disponível para frangos de corte. Arquivo Brasileiro de Medicina Veterinaria e Zootecnia 65:519-525. [ Links ]

Thorp, B. H. and Waddington, D. 1997. Relationships between the bone pathologies, ash and mineral content of long bones in 35-day-old broiler chickens. Research in Veterinary Science 62:67-73. [ Links ]

Turner, C. H. 2006. Bone strength: Current concepts. Annals of the New York Academy of Sciences 1068:429-446. [ Links ]

Turner, C. H. and Burr, D. B. 1993. Basic biomechanical measurements of bone: a tutorial. Bone 14:595-608. [ Links ]

Vieites, F. M.; Nalon, R. P.; Santos, A. L.; Branco, P. A. C.; Souza, C. S.; Nunes, R. V.; Calderano, A. A. and Arruda, N. V. M. 2014. Desempenho, rendimento de carcaça e cortes nobres de frangos de corte alimentados com rações suplementadas com Solanum glaucophyllum. Semina Ciências Agrárias 35:1617-1626. [ Links ]

Wang, X.; Shen, X.; Li, X. and Agrawal, C. M. 2002. Age-related changes in the collagen network and the toughness of bone. Bone 31:1-7. [ Links ]

Zanuzzi, C. N.; Nishida, F.; Portiansky, E. L.; Fontana, P. A.; Gimeno, E. and Barbeito, C. G. 2012. Effects of Solanum glaucophyllum toxicity on cell proliferation and apoptosis in the small and large intestine of rabbits. Research in Veterinary Science 93:336-342. [ Links ]

Received: July 11, 2017; Accepted: November 15, 2017

*Corresponding author: fefelimasc@hotmail.com

Creative Commons License This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.