Selenious acid

Toxicity to birds

Administrative data

Endpoint:

long-term toxicity to birds: reproduction test

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline used. Se concentrations in the food were not verified. Test conditions are well documented.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Dietary Selenium and Arsenic Additions to Diets for Chickens Over a Life Cycle

Author:

Thapar NT, Guenthner E, Carlson CW, Olson OE

Year:

1969

Bibliographic source:

Poultry Science 48: 1988-1993

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

In this study, female chicks were fed diets supplemented with 0, 2 and 8 ppm selenium (added as H2SeO3) through 76 weeks of age. Effects on mortality, body weight, reproductive performance, and progeny were investigated.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Selenious acid

EC Number:

231-974-7

EC Name:

Selenious acid

Cas Number:

7783-00-8

Molecular formula:

H2O3Se

IUPAC Name:

selenous acid

Details on test material:

- selenious acid
- H2SeO3
- No further information on substance stated.

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

HOMOGENEITY AND STABILITY OF TEST MATERIAL IN DIET
- Diet samples were analyzed for Se using the Klein (1943) method. No information reported on sampling frequency, method of analysis, measured concentrations.
- Background Se concentration = 0.5 mg Se/kg diet.

Test organisms

Test organisms (species):

other: Gallus domesticus

Details on test organisms:

TEST ORGANISM
- Common name: chicken
- Source: no data
- Age at test initiation (mean and range, SD): one-day -old
- Weight at test initiation (mean and range, SD): no data
- Sexes used: M/F (only females up to 76 weeks of exposure)
- Housing: battery brooders with wire floors - at 8 weeks of age moved to group cages with wire floors in a windowless layer house

Study design

Limit test:

no

Total exposure duration (if not single dose):

76 wk

No. of animals per sex per dose and/or stage:

2x25 pullets up to 76 weeks of age (males were only exposed for 4 weeks and then sacrificed)

Control animals:

yes

Nominal and measured doses / concentrations:

Nominal: 0, 2.0 and 8.0 mg Se/kg diet
Background Se: 0.5 mg Se/kg diet

Details on test conditions:

TEST CONDITIONS
- Housing: As chicks, the birds were grown in battery brooders with wire floors. At 8 weeks of age, they were moved to group cages with wire floors in a windowless layer house.
- Photoperiod: The lighting was not ideal for growing pullets since they were exposed to 14 hours of light per day throughout the remainder of their life.
- Females were artificially inseminated.

NO. OF BIRDS PER REPLICATE
- For negative control: 25 females
- For treated: 25 females

NO. OF REPLICATES PER GROUP
- For negative control: 2
- For treated: 2

Examinations

Details on examinations and observations:

BODY WEIGHT
- Individual weights were obtained at test initiation, 4 weeks, 20 weeks, and 76 weeks of age.

MORTALITY
- Cumulative mortality was recorded between week 0 and 4, between week 4 and 24, and between week 24 and 76.

REPRODUCTION AND PROGENY
- Cumulative egg production per hen through 76 weeks was recorded.
- Average egg weight (of all eggs layed through 76 weeks) was calculated.
- Feed/egg mass ratio was calculated (kg feed/kg egg).
- % hatch of fertile eggs was recorded.
- Average weight of progeny at four weeks of age (12 hatches at 4-week intervals) was calculated.
- Cumulative mortality was recorded between week 0 and 4 of age for hatched chicks.

PATHOLOGY
- At the termination of the experiment, all hens were sacrificed and examined for abnormal lesions.

Details on reproductive parameters:

see above

Results and discussion

Effect levels

Effect levels 1

Duration (if not single dose):

76 wk

Dose descriptor:

NOEC

Effect level:

2 mg/kg diet

Conc. / dose based on:

element

Remarks:

Se

Basis for effect:

body weight

Remarks:

of dams

Effect levels 2

Duration (if not single dose):

76 wk

Dose descriptor:

NOEC

Effect level:

>= 8 mg/kg diet

Conc. / dose based on:

element

Remarks:

Se

Basis for effect:

mortality

Remarks:

of dams

Effect levels 3

Duration (if not single dose):

76 wk

Dose descriptor:

NOEC

Effect level:

2 mg/kg diet

Conc. / dose based on:

element

Remarks:

Se

Basis for effect:

reproductive parameters

Remarks:

(egg production; egg weight; % hatch of fertile eggs; kg feed/kg egg)

Effect levels 4

Duration (if not single dose):

76 wk

Dose descriptor:

NOEC

Effect level:

2 mg/kg diet

Conc. / dose based on:

element

Remarks:

Se

Basis for effect:

body weight

Remarks:

of 4-week-old progeny

Mortality and sub-lethal effects:

see above

Effects on reproduction:

- A progressively poorer performance of the hens receiving 8 ppm selenium occurred (egg production was at a reduced rate, egg size and body size were smaller, and hatchability of fertile eggs and progeny growth were poorer at each interval in the experiment). Feed efficiency reflected the egg production performance.
- The 2 ppm level of selenium was in no way detrimental to performance. If anything it appeared to enhance growth at about the time of sexual maturity or as shown by the weight data at 20 weeks of age.
- Treatment at 2 ppm was without effect on egg production, egg weight, hatchability or progeny performance. Mortality through the life cycle and for the progeny was lowest for this treatment. Upon necropsy, no evidence of abnormal lesions was found.

Reported statistics and error estimates:

- Duncan's multiple range test (p<0.05).

Any other information on results incl. tables

Table 1. Experiment I - Reproductive Performance of Chickens on Practical Diets Supplemented with Selenium.
Criteria	Basal Diet	2 ppm Se	8 ppm Se
Avg. Body Weight (g)
4 wk. Males	306	300	286
4 wk. Females	280	273	270
Average	293 b^1	286 b	278 a
20 wk. Females	1407 a	1549 b	1370 a
76 wk. Females	2092 b	2085 b	1967 a
Mortality - age, %
0-4 wks.	2.1	0	0
4-24 wks.	6.7	10.9	5.6
24-76 wks.	39.2	30.2	43.8
Egg production - hen-day thru 76 wks.	63.7 c	63.3 c	57.3 aa
Egg wt. (avg. in g thru 77 wks.)	59.3 c	59.3 c	58.7 a
Kg feed/kg egg	3.5 a	3.2 a	4 b
Hatch of fertile eggs, %	90.4 a	90.5 a	53.2 bb
Selenium content (ppm)
Tissues
4 wks. Male liver	0.63	0.89	4.69
76 wks. Female liver	0.41	0.86	3.21
76 wks. Male breast muscle	0.36	0.52	0.45
Eggs
33 wks.	0.58	0.68	1.68
63 wks.	0.29	0.47	1.95
76 wks.	0.41	0.66	1.1
Wt. of progeny at 4 wks. (g - 12 hatched at 4 wk. intervals - 400 + chicks/treatment)
Males	279	276	273
Females	248	250	238
Average	263 b	263 b	255 a
Mortality of progeny, % (0-4 wks.)	14	8	24
Data followed by similar letters are not statistically different at the 0.05 level of probability. With double letters, the differences are significant at the 0.01 level of probability.

 

Applicant's summary and conclusion

Conclusions:

Treatment of pullets with selenium as selenious acid in the diet at concentrations of 0, 2 and 8 mg Se/kg diet for a period of 76 weeks affected reproductive performance in a dose-dependent manner. Effects were manifested as reduced egg production rate, reduced egg size and body size and poor hatchability of fertile eggs and poor progeny growth. The 76-week NOECs were 2 mg Se/kg diet for growth, reproductive performance and progeny weight. No significant effects on mortality were observed up to the highest tested dose (8 mg Se/kg diet).