Registration Dossier

Ecotoxicological information

Toxicity to birds

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
long-term toxicity to birds
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
short-term toxicity to birds: dietary toxicity test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 August 2013 - 21 November 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Principles of method if other than guideline:
The aim of the study was to evaluate the tolerance of chickens for fattening to Butylated Hydroxytol uene (BHT) as technological feed additive (E 321). The study was carried out with 540 chickens at the start of the study. The treatments were: 1) Control group T1: animals fed with basal diet; 2) T2: animals fed basal (T1) diet supplemented with BHT at 150 g/tonne feed (recommended dose); 3) T3: animals fed basal (T1) diet supplemented with BHT at 1000 g/tonne feed (6.7 x recommended dose) and 4) T4: animals fed basal (T1) diet supplemented with BHT at 1500 g/tonne feed (10x recomm ended dose,). The feeds were issued to the appropriate pens for 35 consecutive days. Each feeding treatment was replicated in 9 pens. The data recorded during the feeding phase were live weight (LW) at 0, 10, 28 and 35 days from the start of the study, average daily gains (ADG), daily feed intake and feed:gain ratio (F:G) during the periods 0-10, 10-28, 28-35 and 0-35 days from the start of the study. At 35 days, blood samples were taken from one animal per pen (36 birds in total, 9 per treatment) a nd analysed for routine haematology and biochemistry parameters. The same 36 animals were then sacrificed and necropsied by the veterinary surgeon responsible for animal welfare.
GLP compliance:
yes (incl. certificate)
Dose method:
feed
Analytical monitoring:
yes
Vehicle:
no
Details on preparation and analysis of diet:
DIET PREPARATION
- Description and nutrient analysis of basal diet provided in study report: yes
- Preparation of doses: The test product was supplemented to the basal diets using the vertical and horizontal mixers with a capacity of 0.15 and
0.60 tonnes respectively. With the exception of the test product, the animals did not receive any other product for the total study period. The control feed was free from any zootechnical feed additive as defined in (EC) No 1831/2003. Animals were fed by hand out of coded bags.

NUTRIENT DETERMINATION IN FEED
- When and at what dose levels were samples of treated food analyzed: Nine representative samples of at least 250 g were taken from each test diet: 3 in the beginning, 3 in the middle and 3 in the end of the production process (during the bagging-of the feeds). These 9 samples were pooled to 3 samples in such a way that 1 sample from the beginning, middle and end are pooled together and thoroughly mixed.
- Parameters analysed: Dry matter, crude ash, starch, crude protein content, crude fat content, crude fibre content, carbohydrate and energy content.

BHT ANALYSIS IN FEED
- When and at what dose levels were samples of treated food analyzed: Samples of each test diet for each growing period were taken for analysis (LC-MS/MS).
- Results of homogeneity analysis (range of values): The actual BHT content was within the nominal values and within the tolerance limits given.
- Nominal concentration (mg/kg feed): 0, 150, 1000, 1500 g/ton feed.
- Concentration analysed (mg/kg feed): Not detected, 149.0, 983.3, 1462.1 (mean) (See Table no. 3 below).
- % of nominal: -, 99.3, 98.3, 97.5
- Mixing procedure adequate and variance between nominal and actual dosage acceptable (yes/no): Yes.
Test organisms (species):
other: Chicken (Ross 708)
Details on test organisms:
TEST ORGANISM
- Common name: Chicken
- Source: Via Emilia Km 17 - Longiano (FC) - Italy. Italian AUSL code number: 018 FO 098
- Age at test initiation (mean and range, SD): The chicken used in the present study were chickens for fattening from birth to 35 days old.
- Weight at test initiation (mean and range, SD): 47.1 ± 0.9 g
- Sexes used / mixed or single sex: Males
- Disease free: yes . The animals were selected out of healthy groups in the hatchery. Animals were selected from the same parent stocks and were vaccinated in the hatchery at the day of hatching against Marek’s disease, Paracox for coccidiosis, infectious bronchitis and Newcastle Disease. The animals were also vaccinated during the study against Gumboro disease at D14 and against Newcastle disease at D16.
- Kept according to standard practices: yes
Limit test:
no
Total exposure duration (if not bolus):
35 d
Remarks:
From birth to 35 days old.
No. of animals per sex per dose and/or stage:
540 males
Control animals:
yes, plain diet
Nominal and measured doses / concentrations:
Control T1: Basal diet
T2: T1 + BHT at 150 g/tonne feed (recommended dose, ca. 13.2-22.3 mgBHT/kg bw).
T3: T1 + BHT at 1000 g/tonne feed (6.7 x recommended dose, ca. 94.4-175.5 mgBHT/kg bw).
T4: T1 + BHT at 1500 g/tonne feed (10 x recommended dose, ca. 150.3-268.1 mgBHT/kg bw).
Details on test conditions:
ACCLIMATION
- Acclimation period: No.
- Feeding: During the whole study period the animals were fed ad libitum using one feeder per pen, and fresh drinking water was supplied with a bell drinker for the first 10 days and then with droplet drinkers. The water quality is analytically controlled once a year.
- Health (any disease or mortality observed): The animals were selected out of healthy groups in the hatchery.
- Fasting period before study: No.

PEN SIZE AND CONSTRUCTION MATERIALS
- Description: The net floor space available in each pen was 2.24 square meter (1.4 m x 1.6 m). The pens were aligned in 4 rows with central corridors 1.4 m wide. The pens were accurately cleaned and disinfected before installing the animals in and an ‘empty period’ of at least 7 days was respected to ensure good sanitary conditions in the pens.
- Compliant to good husbandry practices: yes
- Suitable to avoid crowding stress: yes
- Caging: Grouped, 15 chickens per pen. Total of 36 pens in a room.

NO. OF BIRDS PER STAGE OR REPLICATE
- For negative control: 15 (T1)
- For treated: 15 (T2, T3, T4)

NO. OF STAGES OR REPLICATES PER GROUP
- For negative control: 9 (T1)
- For treated: 9 (T2, T3, T4)

TEST CONDITIONS (range, mean, SD as applicable)
- Temperature: The temperature and relative humidity were recorded every 30 minutes
- Room temperature: Within the especifications.
- Relative humidity (%): Within the especifications.
- Photoperiod: 23:1 hours light and dark.
- Ventilation: The ventilation rate varied from 0 m3/hour to the maximum ventilation rate required, according to the desired temperature and the age of the chickens.
Details on examinations and observations:
MORTALITY / CLINICAL SIGNS
- Time schedule for examinations: Twice daily, in the morning and in the afternoon.
- Remarks: General health status was checked, ensuring constant feed and water supply as well as checking the correct temperature and ventilation and unexpected events.

BODY WEIGHT
- Time schedule for examinations: Pen body weights on days 0, 10, 28 and 35. Died animals were also weighed.

FOOD CONSUMPTION
- Time schedule for examinations: Feed intake was accurately measured per pen, taking into account the amounts provided and weighed back between days 0 and
day 10, between day 10 and day 28 and between days 28 and day 35. In order to determine the net feed intake the net weight of feed administered during the trial was recorded. The total quantity administered per period was used to evaluate the intake and the feed:gain ratio (F:G) in each period.
- Remarks: Average feed intake and average body weight per pen were used to calculate the average feed:gain ratio. The adjusted feed:gain ratio was calculated considering the total feed intake per pen divided by the sum of animals live weight and the body weight of the animals died during each period for each replicate.

HAEMATOLOGY:
- Time schedule for examinations: On day 35.
- Dose groups that were examined: Blood samples were taken from one bird per pen (36 chickens for fattening in total, 9 animals per treatment).
- Parameters: RBC, Haemoglobin, Haematocrit, MCV, MCH, MCHC, WBC, Lymphocytes, Monocytes, Neutrophils, Eosinophils, Basophils, Platelets, Reticulocyte count, RPI, MPV, PCT, PDW.

BIOCHEMISTRY:
- Time schedule for examinations: On day 35.
- Dose groups that were examined: Blood samples were taken from one bird per pen (36 chickens for fattening in total, 9 animals per treatment).
- Parameters: RBC, Haemoglobin, Glucose, Calcium, Inorganic P, Cholesterol, Triglycerides, Phospholipids, Uric acid, Urea, Creatinine, Lactate dehydrogenase, Alkaline
Phosphatase, GOT (Aspartate Transaminase), GPT (Alanine Transaminase), Total Bilirubin, GGT, haptoglobin, serum albumin, serum total protein, blood clotting: quick/INR value, prothrombin time (PT), thyroid hormones (TSH, T3, T4).

PATHOLOGY
- Dose groups that were examined: The 36 animals sampled at trial end (D35) for blood collection were sacrificed and necropsied by a veterinary surgeon.
- Terminal necropsy: To assess general health and fitness for human consumption.
- Veterinary necropsy: Checks on: external skin, eyes and any injuries, feet, ears, head and tail, mouth and anus, gut – oral cavity, oesophagus, stomach, upper, mid and lower small intestine, caecum and colon, pancreas, spleen liver/gall bladder, kidneys, genitals, abdominal fat, omentum, heart and lungs, skeletal muscle and fat.


Key result
Duration (if not bolus):
35 d
Dose descriptor:
NOEL
Effect level:
>= 268.1 mg/kg bw/day (actual dose received)
Conc. / dose based on:
test mat.
Basis for effect:
other: No adverse effects observed at the higest dose tested.
Remarks on result:
other: 1500 g/tonne feed (ca. 150,3-268,1 mgBHT/kg bw)
Mortality and sub-lethal effects:
MORTALITY
- Results: The two dead animals were of the treatments T1 and T4, both occurred in the middle of the study (experimental period of 10-28d).
- Remarks: No alterations were found in organs and tissues in both animals nor symptoms of pathological diseas. This deaths were assumed to be not test item related. See Table no. 1 below.

CLINICAL SIGNS
- Results: The general performance parameters,were good and similar to those expected under commercial rearing of chickens for fattening in Italy. The veterinarian considered the animals’ health and husbandry to be generally good with a very low mortality and normal consistency of the faeces.

BODY WEIGHT
- Results: No statistical differences were found among feeding treatments for both parameters for all periods.
- Remarks: See Table no. 3 below.

FOOD CONSUMPTION (if feeding study)
- Results: No statistical differences were found among feeding treatments for both parameters for all periods. In the global study period (D0-D35) the feed:gain ratio was tendentially higher in T4 and T3 groups in comparison with T1 group (1.74 and 1.74 vs. 1.66 for T4, T3 and T1 groups respectively; P=0.0723).
- Remarks: See Table no. 4 below.

HAEMATOLOGY:
- Results: All measured haematological parameters were within the respective reference ranges. No statistical differences were found among feeding treatments with the exception of monocytes that was higher in T2 vs. T1 and T4 groups (2.80 vs. 2.21 and 2.29 % respectively; P=0.0278) but no difference occurred between T1 and T4 group. The absence of reticulocyte and RPI could be an index of a good sanitary status of the animals.
- Remarks: See Table no. 5 below.

BIOCHEMISTRY:
- Results: All measured biochemical parameters were within the respective reference ranges. Urea was lower in T3 vs. T1 and T2 groups (respectively 5.10 vs. 6.22 and 6.38 mg/dl; P = 0.0402) but no difference occurred between T1 and T4 group. Creatinine was lower in T3 vs. T1 and T2 groups (respectively 0.53 vs. 0.61 and 0.60 mg/dl; P = 0.0414) but no difference occurred between T1 and T4 group. Bilirubin was tendentially higher in T2 vs. T3 and T4 groups (respectively 0.14 vs. 0.11 and 0.11 %; P = 0.0795) but no difference occurred between T1 and T4 group. No differences were observed between the control and the treatment groups regarding neither the thyroid hormones (TSH, T3, T4) nor hepatic function related enzymes (GOT, GPT, GGT).
- Remarks: See Tables no. 6 and 7 below.

PATHOLOGY
- Results: No statistical differences were found among feeding treatments for all parameters of necropsy.
- Remarks: See Table no. 8 below.

Further details on results:
No differences were observed between the control and the treatment groups regarding neither the thyroid hormones (TSH, T3, T4) nor hepatic function related enzymes (GOT, GPT, GGT).
Reported statistics and error estimates:
Student “t” Test was used to compare the means of each group. The level of significance to indicate differences stated in the ANOVA model were P≤0.05 when the difference was statistically significant, while 0.05

Table 1. Mortality:

Experimental periods

 

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000 g/ton. feed

T4

BHT

1500 g/ton. feed

0-10 d

n.

0

0

0

0

10 - 28 d

n.

1

0

0

1

28 - 35 d

n.

0

0

0

0

0 - 35 d

n.

1

0

0

1

Total mortality / culling

%

0.74

0

0

0.74

0.37

Table 2. BHT content in feed:

Study

periods

BHT, mg/kg (mean ± standard deviation, n=4)

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000 g/ton. feed

T4

BHT

1500 g/ton. feed

D0-D10

Not detected

147.4±6.1

968.7±31.6

1419.4± 16.6

D10-D28

Not detected

156.7±6.4

1025.9±38.0

1448.4±58.6

D28-D35

Not detected

143.0±2.4

955.4±20.0

1518.9±35.7

Table 3. Body weights:

Live weight and average daily gain (mean; n = 9)

Experimental period

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000g/ton. feed

T4

BHT

1500 g/ton. feed

Treatment

Effect (P)

Standard error of the mean

Live weight (g)

D0

47.0

47.3

47.0

47.1

0.8749

0.3091

D10

215.6

212.4

212.4

213.4

0.8467

2.8989

D28

1168.4

1169.0

1149.5

1120.9

0.1013

15.0653

D35

1655.6

1634.8

1633.0

1598.1

0.2925

20.9656

Average daily gain (g)

D0-D10

16.9

16.5

16.5

16.6

0.8087

0.2779

D10-D28

52.9

53.1

52.1

50.3

0.0676

0.7770

D28-D35

69.6

66.5

69.1

68.2

0.6973

1.9354

D0-D35

45.9

45.4

45.3

44.2

0.2818

0.6011

Table 4. Food intake and food gain:

Feed intake and feed:gain ratio (mean; n = 9)

Experimental

period

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000g/ton. feed

T4

BHT

1500 g/ton. feed

Treatment

Effect (P)

Standard error of the mean

Feed intake (g)

D0-D10

24.0

23.2

23.5

24.6

0.2884

0.5452

D10-D28

82.9

87.0

87.1

84.0

0.2669

1.8105

D28-D35

132.7

129.4

137.5

134.5

0.2839

2.9387

D0-D35

75.9

77.2

79.0

77.0

0.4601

1.3620

Feed:Gain ratio

D0-D10

1.42

1.40

1.42

1.48

0.3331

0.0293

D10-D28

1.57

1.64

1.67

1.67

0.1358

0.0338

D28-D35

1.91

1.95

1.99

1.99

0.4622

0.0397

D0-D35

1.66

1.70

1.74

1.74

0.0723

0.0256

Tabla 5. Haematology:

Blood haematological parameters after 35 days from the start of the study (mean; n = 9)

 

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000g/ton. feed

T4

BHT

1500 g/ton. feed

Treatment effect (P)

Standard error of the mean

WBC (1,000/ml)

19.64

19.57

17.84

18.19

0.5147

1.05133

RBC (1,000,000/ml)

2.53

2.51

2.49

2.43

0.6444

0.05651

Haemoglobin (%)

12.89

12.83

12.54

12.41

0.6245

0.29756

Haematocrit (%)

31.20

29.94

29.72

30.39

0.6610

0.89137

MCV (fl)

123.56

119.33

119.44

124.44

0.2671

2.28876

MCH (pg)

50.84

51.11

50.47

51.11

0.6862

0.43197

MCHC (%)

41.37

42.86

42.21

41.28

0.4243

0.76405

Neutrophils (%)

26.83

30.50

26.67

28.84

0.7711

2.96711

Lymphocytes (%)

67.71

63.82

68.17

65.91

0.7177

2.94052

Monocytes (%)

2.21 a

2.80 b

2.50 ab

2.29 a

0.0278

0.14164

Eosinophils (%)

0.87

0.90

0.76

0.74

0.6599

0.10679

Basophils (%)

2.38

1.98

1.91

2.21

0.3768

0.20807

Platelets (1,000/mmc)

64.77

62.52

62.52

62.47

0.7332

0.72566

Reticulocyte (%)

0.00

0.00

0.00

0.00

-

-

RPI (%)

0.00

0.00

0.00

0.00

-

-

MPV (fl)

8.52

8.98

8.85

8.88

0.3404

0.18535

PCT (%)

0.39

0.39

0.44

0.40

0.7358

0.03679

PDW

19.78

18.85

19.28

19.29

0.3087

0.34608

WBC = white blood cells; RBC = red blood cells; MCV = mean volume of erythrocytes; MCH = mean content of haemoglobin; MCHC = mean concentration of haemoglobin in erythrocytes; RPI = Reticulocyte production index; MPV = mean platelet volume; PCT = platelet crit (percent volume of the blood occupied by platelets); PDW = platelet distribution width.

a,b.: Different letters in the same row = differences significant (P<0.05)

Table 6. Biochemistry:

Blood biochemical parameters after 35 days from the start of the study (mean; n = 9)

 

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000g/ton. feed

T4

BHT

1500 g/ton.feed

Treatment 

Effect (P)

Standard error of the mean

Glucose (mg/dl)

226.89

222.56

221.33

224.11

0.8476

4.62706

Urea (mg/dl)

6.22 b

6.38 b

5.10 a

5.79 ab

0.0402

0.32302

Uric acid (mg/dl)

5.57

5.55

5.75

5.82

0.5774

0.16109

Creatinine (mg/dl)

0.61 b

0.60 b

0.53 a

0.58 ab

0.0414

0.02035

Cholesterol (mg/dl)

142.89

140.00

131.67

132.33

0.3788

5.41952

Triglycerides (mg/dl)

87.56

89.78

86.44

90.89

0.9213

5.04318

Total Bilirubin (mg/dl)

0.12

0.14

0.11

0.11

0.0795

0.00850

GOT (U/l)

198.99

213.89

215.44

199.11

0.2819

7.86361

GPT (U/l)

12.56

13.56

13.22

13.33

0.6952

0.61802

GGT (U/l)

17.56

15.22

16.00

15.89

0.2808

0.85527

Alkaline phosphatase (U/l)

491.44

484.22

508.00

496.78

0.6483

13.43985

Lactate dehydrogenase (U/l)

926.67

976.44

913.78

925.44

0.1334

19.68379

Calcium (mg/dl)

12.28

11.46

11.20

12.22

0.1253

0.37847

Inorganic P (mg/dl)

9.19

8.60

8.40

8.97

0.7749

0.58202

Phospholipides (mg/dl)

284.56

267.89

256.67

272.56

0.4827

12.60750

Haptoglobin (mg/dl)

5.30

4.40

5.01

5.16

0.2148

0.31577

Serum albumin (g/dl)

1.15

1.14

1.09

1.17

0.1275

0.02474

Serum total protein (g/dl)

5.56

5.56

5.47

5.50

0.9132

0.10515

INR value

1.52

1.42

1.50

1.51

0.8452

0.08700

Prothrombin value (sec)

14.77

15.10

15.24

15.24

0.8672

0.45918

TSH (mU/ml)

0.33

0.39

0.33

0.29

0.5962

0.05305

T3 (mU/ml)

6.76

6.68

6.34

6.91

0.5258

0.27455

T4 (mU/ml)

0.85

0.86

0.86

0.81

0.8721

0.04954

GOT = Aspartate Transminase; GPT = Alanine Transminase, GGT = gamma-glutamyl transpeptidase, INR value = International Normalised Ratio; TSH = Thyroid stimulating hormone; T3 = Triiodothyronine; T4 = Thyroxine.

Table 7: Individual results on TSH, T3 and T4 (thyroid hormones):

Treatment

Pen

TSH

FT3

FT4

T1

1

0.22

6.5

0.77

T1

5

0.33

6.6

0.61

T1

10

0.19

5.8

0.84

T1

12

0.57

7.7

1.2

T1

20

0.31

7.5

0.74

T1

21

0.26

7.6

0.88

T1

24

0.59

6.1

0.87

T1

25

0.33

5.4

0.85

T1

31

0.16

7.6

0.85

T2

2

0.26

6.4

0.71

T2

9

0.44

5.1

0.8

T2

13

0.33

6.9

0.98

T2

17

0.22

6.7

0.65

T2

18

0.25

7.1

0.91

T2

19

0.34

7.3

0.99

T2

30

0.94

7.7

0.79

T2

32

0.17

6.8

0.87

T2

34

0.55

6.1

1.02

T3

3

0.27

5.3

0.79

T3

8

0.46

7.9

0.75

T3

11

0.41

5.6

0.77

T3

14

0.54

6.8

0.94

T3

16

0.37

6.5

0.81

T3

23

0.24

6.7

1.2

T3

27

0.19

6.8

0.78

T3

28

0.36

6.1

0.74

T3

35

0.16

5..4

0.99

T4

4

0.34

5

0.64

T4

6

0.27

7.7

0.66

T4

7

0.21

7.1

0.81

T4

15

0.34

56.7

0.78

T4

22

0.22

7.8

0.71

T4

26

0.21

7

1.01

T4

29

0.35

7

0.69

T4

33

0.24

6.6

0.99

T4

36

0.39

7.3

1

Tabla 8. Necropsy:

Necropsy results (mean; n = 9)

Experimental period

T1

Control

T2

BHT

150 g/ton. feed

T3

BHT

1000g/ton. feed

T4

BHT

1500 g/ton. feed

Treatment

Effect(P)

Standard error of the

mean

External skin

0.11

0.00

0.00

0.11

0.5787

0.07857

Leg

0.22

0.11

0.22

0.22

0.9224

0.13889

Eyes

0.00

0.00

0.00

0.00

_

_

Anus

0.11

0.11

0.00

0.00

0.5787

0.07857

Oral cavity

0.00

0.00

0.00

0.00

_

_

Oesophagus

0.00

0.00

0.00

0.00

_

_

Stomach

0.11

0.11

0.00

0.00

0.5787

0.07857

Gizzard

0.00

0.00

0.00

0.00

_

_

Small intestine

0.22

0.22

0.22

0.11

0.9224

0.13889

Caecum

0.11

0.00

0.11

0.00

0.5787

0.07857

Colon

0.11

0.11

0.11

0.11

1.0000

0.11111

Pancreas

0.00

0.00

0.00

0.00

_

_

Liver

0.22

0.33

0.22

0.22

0.9395

0.15215

Lungs

0.11

0.11

0.00

0.11

0.8013

0.09623

Kidneys

0.00

0.00

0.00

0.00

_

_

Heart

0.00

0.00

0.00

0.00

_

_

Muscle

0.22

0.00

0.11

0.00

0.2808

0.09213

Fat

0.11

0.00

0.11

0.00

0.5787

0.07857

Score: 0 = no alteration found;1=slight alterations; 2 = alteration of medium intensity; 3 = serious alteration

Validity criteria fulfilled:
not applicable
Conclusions:
The administration of BHT to chickens for fattening for 35 consecutive days up to 1500 g/tonne feed (ca. 150,3-268,1 mgBHT/kg bw), did not cause any adverse effects under the test conditions. No adverse effects were observed related neither to the thyroid hormones (TSH, T3, T4) nor hepatic function (GOT, GPT, GGT).
Executive summary:

In the present study, the tolerance of of chickens for fattening to Butylated hydroxytoluene (BHT) as technological feed additive was evaluated (GLP study). The study was carried out with 540 chickens at the start of the study. The treatments were: 1) Control group T1: animals fed with basal diet; 2) T2: animals fed basal (T1) diet supplemented with BHT at 150 g/tonne feed (recommended dose, ca. 13.2 -22.3 mgBHT/kg bw)); 3) T3: animals fed basal (T1) diet supplemented with BHT at 1000 g/tonne feed (6.7 x recommended dose, ca. 94.4 -175.5 mgBHT/kg bw) and 4) T4: animals fed basal (T1) diet supplemented with BHT at 1500 g/tonne feed (10x recommended dose, ca. 150.3 -268.1 mgBHT/kg bw). The feeds were issued to the appropriate pens for 35 consecutive days. Each feeding treatment was replicated in 9 pens. The data recorded during the feeding phase were live weight (LW) at 0, 10, 28 and 35 days from the start of the study, average daily gains (ADG), daily feed intake and feed:gain ratio (F:G) during the periods 0-10, 10-28, 28-35 and 0-35 days from the start of the study. At 35 days, blood samples were taken from one animal per pen (36 birds in total, 9 per treatment) and analysed for routine haematology and biochemistry parameters. The same 36 animals were then sacrificed and necropsied by the veterinary surgeon responsible for animal welfare. The results of the study show a low mortality. The animals were in good general health as recorded during the veterinary inspections. No statistical differences were found among feeding treatments for the all performance parameters; only in the global period of the trial (D0-D35) the feed:gain ratio was tendentially higher in T4 and T3 groups in comparison with T1 group. Concerning the blood parameters statistical differences were found for: Monocytes that were higher in T2 vs. T1 and T4 groups but no difference occurred between T1 and T4 group; Urea was lower in T3 vs. T1 and T2 groups but no difference occurred between T1 and T4 group; Creatinine was lower in T3 vs. T1 and T2 groups but no difference occurred between T1 and T4 group; Bilirubin was tendentially higher in T2 vs. T3 and T4 groups but no difference occurred between T1 and T4 group. All measured blood haematological and biochemical parameters were within the respective reference ranges. No statistical differences were found among feeding treatments for the all necropsy evaluations. In conclusion, the administration of BHT to chickens for fattening for 35 consecutive days up to 1500 g/tonne feed (ca. 150,3-268,1 mgBHT/kg bw), did not cause any adverse effects under the test conditions. It should be highlighted that no test item related adverse effects were observed regarding neither the thyroid hormones (TSH, T3, T4) nor the hepatic function (GOT, GPT, GGT).

Description of key information

In accordance with column 2 of REACH Annex X, long-term or reproductive toxicity to birds studies do not need to be conducted taking into account the large mammalian dataset that is available.

The administration of BHT to chickens for fattening for 35 consecutive days up to 1500 g/tonne feed (ca. 150,3-268,1 mgBHT/kg bw), did not cause any adverse effects under the test conditions. No adverse effects were observed related neither to the thyroid hormones (TSH, T3, T4) nor hepatic function (GOT, GPT, GGT).

Key value for chemical safety assessment

Additional information