J. Sci. FdAgric. 1975, 26, 311-318

Influence of Dietary Rapeseed Meals and Selenium on Egg Production and Egg Tainting in Laying Hens

Robert Blair, Alexander R. Robblee, William A. Dewar, William Bolton and Norman D. Overfield“

Agricultural Research Council’s Poultry Research Centre, King’s Buildings, West Mains Road, Edinburgh EH9 3JS, Scotland, and “Ministry of Agriculture, Fisheries and Food, Agricultural Development and Advisory Service, Government Buildings, Lawnswood, Leeds LS16 5P Y (Manuscript received 5 August 1974 and accepted 4 October 1974)

In 3 experiments I52 hens of differing strains were fed diets containing 0, 50 or 100 g Span, Canadian or Europeanrapeseed meal per kg. Two strains, Shaver 288 and Babcock B300, laid white-shelled eggs while three other strains, Shaver 585, Warren 14 and Thomber 404 laid brown-shelled eggs. Egg production performance was not significantly affected by the inclusion of rapeseed meal in the diet. However the strains laying brown-shelled eggs laid a high proportion of tainted eggs when rapeseed meal was included in the diet. All rapeseed meals led to a similar degree of tainting. Supplementing the diets with 1 or 2 mg selenium per kg did not significantly affect the incidence of tainting. Shell thickness, albumen height and Haugh unit were unaffected by the presence of rapeseed meal in the diet, and yolk colour was improved by the inclusion of Canadian and European rapeseed meals. On the basis of these and other findings it is recommended that rapeseed meal be omitted from diets at least for hens that lay brown-shelled eggs until the taint problem has been solved.

1. Introduction

There is an incentive to include rapeseed meal (RSM) in poultry diets for it is attrac- tively priced and oilseed rape has been given official encouragement as a growing crop within the E.E.C. Accordingly the U.K. production is expected to rise from 35 000 tons in 1973 to over 200 000 tons by 1978.l Because the glucosinolates present in RSM yield goitrogens on hydrolysis2 a maximal limit of 5-10% RSM has been suggested in layer diek3v4

One further problem with layers has emerged recently. Vogt et ~ 1 . ~ reported an unusual odour in white-shelled eggs with as little as 8 % RSM in the diet and Marangos6 reported a “fishy” taint in eggs from hens fed RSM. Similar taints have been reported from commercial flocks,’ some hens also having an offensive odour in the breath.

The object of the experiment described in this report was to investigate the incidence of egg taint in different strains of laying hen when RSMs of different types were included

a A. R. Robblee was on leave from University of Alberta, Edmonton, Alberta, Canada. N. D. Over- field is a national specialist in egg quality.

311

312 R. Blair ef al.

in the diet at 5 or 10 %. The selenium contents of some RSMs are high8,9 and since it is well known that cattle grazing high-selenium pasture in the U.S.A. exhibit a garlic- like odour in the breath the diets were also supplemented with selenium.

2. Experimental 2.1. Experiment 1 Thirty-six light hybrids of White Leghorn type (Shaver 288) aged 9 months and laying at about 90 % were caged individually in a windowless room in which artificial lighting was provided for 18 h daily. The hens were then allotted randomly to one of four dietary treatments, namely (1) control, (2) 100 g Span RSM per kg, (3) 1 mg selenium (as sodium selenite) per kg, and (4) 100 g Span RSM plus 1 mg selenium per kg diet. Span RSM contains a low level of erucic acid in the lipid fraction. The experiment lasted 4 weeks.

Table 1. Compositions of diets used in experiment 1 (g/kg)

Diet no. ~

1.1 1.2 1.3 1.4

Maize meal Wheat meal Barley meal Maize oil Grass meal Herring meal Soyabean meal Rapeseed meal Ground limestone Dicalcium phosphate Salt (NaCl) Choline supplement" DL-methionine Vitamin and mineral supplement* Selenium supplement"

250.0 250.0 233.6

5.0 20.0 50.0

100.0

70.0 12.5 2.5 0.2 1 .o 5.0

-

-

250.0 250.0 189.6 19.0 20.0 50.0 30.0

100.0 70.0 12.5 2.5 0.2 1 .o 5.0 -

250.0 250.0 233.6

5 .O 20.0 50.0

100.0

70.0 12.5 2.5 0.2 1 .o 5.0 +

-

250.0 250.0 189.6 19.0 20.0 50.0 30.0

100.0 70.0 12.5 2.5 0.2 1 .o 5.0 +

Contained 500 g choline chloride/kg. Provided per kg diet: 6000 i.u. vitamin A; 800 i.u. vitamin D; 25 mg vitamin E; 1.3 mg menaph-

thone; 4 mg riboflavin; 28 mg nicotinic acid; 10 mg panthothenic acid; 3.5 mg Cu; 0.4 mg I; 45 mg Fe; 300 mg Mg; 100 mg Mn and 50 mg Zn.

Provided 1 mg Se per kg diet.

The compositions of the diets used are shown in Table 1. With the exception of the choline and methionine supplements, diet 1 was the standard layer diet in use at that time at the ARC Poultry Research Centre. Span RSM was included in the appropriate diets at the expense of barley and soyabean meal and to maintain each diet isonitro- genous and isoenergetic the content of maize oil was increased.

Egg production and bird mortality were recorded. In addition all eggs laid were tested for taint in the following manner, as devised by the Agricultural Development

Influence of rapeseed and selenium on egg production 313

and Advisory Service in collaboration with the ARC Food Research Institute. The eggs were tested on the day of lay or the succeeding day. Each egg was broken out and the internal surface of the shell was sniffed by a panel of two persons. The egg contents were then mixed in a beaker using a glass rod and again sniffed by the taint panel. Each egg was scored on a scale from 0 to 5 in which a score of 0 indicated the absence of fishy odour and a score of 5 indicated a very strong fishy odour in the egg. However, since scoring was subjective and somewhat liable to disagreement only the presence or absence of taint was taken into account in analysing the results. Previous taint tests showed that on this basis the taint panel made a consistent assessment of egg odours.

2.2. Experiment 2

Ninety-six pullets at point of lay, comprising 36 Babcock B300 and 30 each of Shaver 585 and Warren 14, were caged individually in a windowless house in which artificial lighting was provided for 18 h daily. Equal numbers from each strain were allotted to one of 6 dietary treatments, namely (1) control, (2) 50 g Span RSM per kg, (3) 100 g Span RSM per kg, (4) 100 g Canadian RSM per kg, (5) 50 g European RSM per kg, and (6) 100 g European RSM per kg. Allotment to treatments was on the basis of a statistical plan. Both the Canadian and European meals were of unspecified variety but were probably Brussicu campestris and B. nupus, re~pectively.~ The compositions of the diets used are shown in Table 2. All diets were formulated to be isoenergetic and isonitrogenous. Diet 2.1 was similar to diet 1.1 used in experiment 1.

Table 2. Compositions of diets used in experiment 2 (g/kg)

Diet no.

2.1 2.2 2.3 2.4 2.5 2.6

Maize meal Wheat meal Barley meal Maize oil Grass meal Herring meal Soyabean meal Ground limestone Dicalcium phosphate Salt (NaCl) Choline supplement" DL-methionine Vitamin and mineral supplement" Span RSM Canadian RSM European RSM

250.0 250.0 233.6

5.0 20.0 50.0

100.0 70.0 12.5 2.5 0.4 1 .o 5.0 - - -

250.0 250.0 21 1.6 12.0 20.0 50.0 65.0 70.0 12.5 2.5 0.4 1 .o 5.0

50.0 - -

250.0 250.0 189.6 19.0 20.0 50.0 30.0 70.0 12.5 2.5 0.4 1 .o 5.0

100.0 - -

250.0 250.0 250.0 250.0 189.6 211.6 19.0 12.0 20.0 20.0 50.0 50.0 30.0 65.0 70.0 70.0 12.5 12.5 2.5 2.5 0.4 0.4 1 .o 1 .o 5.0 5.0 - -

100.0 - - 50.0

250.0 250.0 189.6 19.0 20.0 50.0 30.0 70.0 12.5 2.5 0.4 1 .o 5.0 - -

100.0

a See Table 1,

Records were maintained of feed consumption, egg production, egg weight and bird mortality. In addition all eggs laid on one day per week were tested for taint, as described in experiment 1.

314 R. Blair el al.

All eggs laid on one other day per week were collected. Shell thickness was measured with a micrometer screw gauge, yolk colour by comparison with the Roche fan and Haugh units with an electronic albumen height meter.1°

2.3. Experiment 3 Twenty medium bodyweight Thornber pullets aged 6 months and laying at about 70 % were caged individually, as in experiment 1. The hens were allotted randomly but in equal numbers to one of 4 dietary treatments, namely (1) control, (2) 100 g Span RSM per kg, (3) 2 mg selenium per kg and (4) 100 g Span RSM plus 2 mg selenium per kg. The diets used were similar to those used in Experiment I except that the supplementary level of selenium was increased from 1 to 2 mg per kg.

Records were maintained of egg production, hen mortality and egg taint, as in experiment 1.

3. Results 3.1. Experiment 1 Egg production was depressed both by inclusion of rapeseed meal and selenium in the diet (Table 3) but neither effect was significant at P < 0.05. No tainted eggs were found and no birds died during the course of the experiment.

Table 3. Experiment 1. Effects of dietary rapeseed meal (RSM) and selenium on egg production and egg tainting in light hybrids of W. Leghorn type

Diet no. S.e. and significance of difference between

1.1 1.2 1.3 1.4 RSM or Se meansa

RSM level (g/kg) 0 100 0 100 Se level (mg/kg) 0 0 1 1

Hens laying tainted eggs 0 0 0 0 % Egg production 104.4 98.0 92.5 92.9 2.39 NS

Number of eggs tested 263 247 233 234

a NS = not significant at P < 0.01.

3.2. Experiment 2 Percentage egg production, mean egg weight, feed intake and mortality (Table 4) were not influenced significantly by the level or type of rapeseed meal included in the diet. Some differences due to breed were observed but were not significant at P < 0.05. Total deaths were 8, of which 5 were Babcock B300 and 3 were Shaver 585. The causes of death were nephritis, leucosis or Marek’s disease.

The incidence of egg tainting (Table 5 ) indicated that all rapeseeds tested led to a similar degree of tainting and that the level of tainting increased with the level of rapeseed meal in the diet. Large strain differences were observed. The Babcocks laid very few tainted eggs, whereas with the Warrens a high proportion and with the Shavers a very high proportion of the eggs was tainted. Out of the 30 Shaver and 30 Warren hens, I6 and 12, respectively, were found to lay tainted eggs on more than one occasion. The remaining 14 and 18 hens, respectively, laid no tainted eggs. A few tainted eggs were found with the control diet.

Influence of rapeseed and selenium on egg production 315

Table 4. Experiment 2. Effects of bird strain and of level and type of rapeseed meal (RSM) in the diet on laying performance

Dietary treatment S.e. and significance

50 g/kg 100 g/kg 100 g/kg 50 g/kg 100 g/kg of difference Span Span Canadian European European between

Control RSM RSM RSM RSM RSM Strain strain (2.1) (2.2) (2.3) (2.4) (2.5) (2.6) means means'

% eggproduction Babcock 95.8 81.5 91.0 83.1 72.5 Warren 104.0 82.4 102.1 84.8 103.6 Shaver 77.7 74.5 91.1 84.5 96.0 means 92.7 79.6 93.5 84.0 89.5

S.e. and significance of difference between diet means 4.38 NS Mean egg weight ( g )

Babcock 49.2 50.7 49.4 49.3 53.8 Warren 53.4 53.8 50.5 52.2 51.1 Shaver 48.9 50.8 50.3 52.1 51.5 means 50.4 51.7 50.0 51.1 52.2

S.e. and significance of difference between diet means 0.82 NS Feed intake per hen per day ( g )

Babcock 106.2 103.7 107.9 98.0 94.4 Warren 128.4 117.2 119.7 114.6 120.6 Shaver 117.9 114.3 116.6 112.1 116.9 means 116.8 111.2 114.3 107.6 115.2

S.e. and significance of difference between diets means 3.24 NS Mortality, number dead with total number in the group in parenthesis

Babcock O(6) O(6) l(6) l(6) 3(6) Warren O(5) O(5) O(5) O(5) O(5) Shaver 1(5) O(5) 10) O(5) Totals l(16) O(16) 2(16) l(16) 3(16)

85.1 77.1 92.5 85.0

49.2 52.2 49.6 50.3

96.2 109.7 109.7 104.6

O(6) O(5) 1(5)

1u6)

84.9 92.4 86.1

50.3 52.2 50.5

101.1 118.3 117.5

Totals 5(36)

300) ~ 3 0 )

3.06 NS

0.60 NS

2.26 NS

a As in Table 3.

Table 5. Experiment 2. Effects of bird strain and of level and type of rapeseed meal (RSM) in the diet on the incidence of egg tainting

Strain

Babcock Shaver Warren B300 585 14

Number of birds per treatment 6 5 5

Number of birds producing tainted eggs, with total number of tainted eggs in parenthesis Dietary treatment

2.1 Control l(1) 0 2(2) 2.2 50 g/kg Span RSM 0 3(3) 2(3) 2.3 100 g/kg Span RSM 0 5(28) 2(7) 2.4 100 g/kg Canadian RSM 1(1) 4(28) 1(5) 2.5 50 g/kg European RSM 0 30 3) 3(W 2.6 100 g/kg European RSM 0 4(14)

316 R. Blair et uf.

Results on other egg quality measurements are shown in Table 6 . There was a significant (P < 0.001) effect of breed on shell thickness but no significant effect due to diet and no significant interaction effect. Neither albumen height nor Haugh unit was affected significantly by breed or diet but it was found that the inclusion of European or Canadian RSM in the diet enhanced yolk colour significantly (P < 0.01).

Table 6. Experiment 2. Effects of bird strain and of level and type of rapeseed meal (RSM) in the diet on egg quality measurements

Dietary treatment

50 g/kg 100 g/kg 100 g/kg 50 g/kg 100 g/kg Control Span Span Canadian European European Strain

(2.1) RSM(2.2) RSM(2.3) RSM(2.4) RSM(2.5) RSM(2.6) means

Shell thickness (mm) Babcock 0.353 Warren 0.316 Shaver 0.283 Diet means 0.317

Babcock 8.552 Warren 9.39 Shaver 7.963 Diet means 8.635

Babcock 95.0 Warren 97.3 Shaver 91.2 Diet means 94.5

Babcock 5.4 Warren 5.7 Shaver 6.2 Diet means 5.8

Albumen height (mm)

Haugh units

Yolk co/our (units)

0.352 0.302 0.289 0.314

9.1 9.174 8.0 8.758

97.1 94.3 90.9 94.1

5.5 5.8 5.5 5.6

0.343 0.302 0.294 0.313

7.662 8.436 8.28 8.126

90.0 93.9 93.6 92.5

5.9 5.8 5.6 5.8

0.362 0.33 0.296 0.329

7.542 8.622 9.1 1 8.425

88.8 94.3 95.9 93.0

5.6 6.5 6.5 6.2

0.356 0.320 0.297 0.324

8.066 9.594 9.275 8.978

91.7 98.5 97.0 95.7

6.1 6.0 6.5 6.2

0.340 0.308 0.314 0.321

8.56 8.102 8.498 8.387

94.5 92.0 93.9 93.5

6.6 6.5 6.5 6.5

0.351 0.313 0.295 0.32

8.247 8.886 8.521 8.551

92.8 95.0 93.7 93.9

5.9 6.0 6.1 6.0

3.3. Experiment 3 Egg production was not significantly influenced by the level of rapeseed meal or of selenium in the diet (Table 6). Hens fed the diets containing rapeseed meal laid some

Table 7. Experiment 3. Effects of dietary rapeseed meal (RSM) and selenium on egg production and egg tainting in medium hybrids (Thornber 404)

Diet no. S.e. and significance of difference between

3.1 3.2 3.3 3.4 RSM or Se means" ~ ~~

RSM level (g/kg) 0 100 0 100 Se level (mg/kg) 0 0 2 2

Hens laying tainted eggs 0 3 1 3 Number of eggs tested 109 105 103 1 04 - Number of tainted eggs 0 13 1 5

% Egg production 77.9 75.0 73.6 74.7 3.32 NS - -

a NS = not significant at P <: 0.05.

Influence of rapeseed and selenium on egg production 317

tainted eggs, but supplementing the diet with selenium had only a very slight influence on egg taint. In the group fed diet 2 it was found that 10 out of the 13 tainted eggs were laid by one hen, and that the 3 other tainted eggs were laid by 2 hens. In the group fed diet 4, the 5 tainted eggs were laid by 3 hens. No bird died during the course of the experiment.

4. Discussion Until recently it has been generally agreed that rapeseed meal (RSM) can be included satisfactorily at low levels in layer diets.4, l1 However, most investigations have been carried out with hens laying white-shelled eggs. The results of the experiments described in this report show that a high proportion of at least some strains of hens laying brown- shelled eggs are liable to produce tainted eggs when fed diets containing low levels of RSM. These results bear out field reports that circumstantially linked egg taint in certain strains with the presence of RSM in the feed.7*12

The results indicate effects due to strain of bird and to individuals within a strain. Shaver 288s laid no tainted eggs, Babcocks laid very few, whereas Warrens laid a high proportion and Shaver 585s a very high proportion. About 53 of the Shaver 585s and 40 % of the Warrens repeatedly laid eggs that were tainted. The remaining Shavers and Warrens produced no tainted eggs. The Thornber 404s also produced tainted eggs. The Babcocks and the Shaver 288s laid white-shelled eggs, while the Thornber 404s, Warrens and Shaver 585s laid brown-shelled eggs.

Detailed analyses of the RSMs used in our experiments (and a number of other samples) were carried out to determine whether any factor such as progoitrin level might have been associated with tainting. However, apart from higher contents of progoitrin (oxazolidinethione) and selenium in B. campestris, the samples were similar chemically' and produced similar tainting. The factor responsible therefore seems to be common to both B. napus and B. campesfris varieties and is probably not detected by normal chemical tests used in feedingstuffs analysis. There is no evidence either to suggest that selenium is involved, although the content of this element in B. carrpestris RSM8,9 is high.

Workers at the ARC Food Research Centre13 have been able to induce egg taint in certain birds by feeding a diet containing particular batches of RSM. They have also been able to reproduce the effect in some birds by feeding trimethylamine and they suggest that the ability of hens to produce taint is probably linked with an ability to metabolise trimethylamine. This could explain our finding that only certain strains and certain individuals within the strains were found to lay tainted eggs. The origin of the trimethylamine found in eggs has yet to be defined.13

These results confirm that RSM can probably be included in layer diets without significant effect on egg production although in our experiments there was a tendency for slightly lower production with RSM in the diet which could have been associated with decreased feed intake. Egg quality is also unaffected and yolk colour may even be improved by inclusion of certain RSMs. However, the finding that egg taint can result from the feeding of RSM to laying hens makes it necessary to omit this feedingstuff from diets at least for hens that lay brown-shelled eggs14 until a solution is found to the taint problem.

318 R. Blair ef ul.

Acknowledgements We are grateful to Mr R. Morley Jones for help with the statistical analyses of the results, and to Mr K. N. Grant for technical assistance and to Mrs M. Grant and Mr M. M. MacCowan and his staff for help with the care of the birds.

References 1. 2.

3.

4.

5. 6. 7. 8. 9.

10. 11. 12. 13. 14.

Bird, D. Canadian Feed Manufacturers’ Convention 1973, Winnipeg, Manitoba. Bell, J. M.; Belzile, R. J. Rapeseed meal for livestock andpoultry+ review Publ. No. 1257,1965, p. 45, Canada Department of Agriculture. Clandinin, D. R. Rapeseed meal for livestock andpoultry-a review. Publ. No. 1257,1965, p. 81, Canada Department of Agriculture. Clandinin, D. R. ; Robblee, A. R. ; Slinger, S . J. In Canadian Rapeseed Meal in Poultry and Animal Feeding, 1973, p. 11, Winnipeg, Manitoba, Rapeseed Association of Canada. Vogt, H. ; Schubert, H. J. ; Stute, K.; Rauch, W. Arch. GeBugelk. 1969,33,119. Marangos, A. Personal communication, 1973. Overfield, N. D.; Elson, H. A. Br. Poult. Sci., 1975,16, 213. Arthur, D. Can. J. Anim. Sci. 1971,51,71. Blair, R.; Scougall, R. K. Feedstuffs, Minneap. 1975,47, (6), 26. Barker, P. H.; Watt, N. L. Unpublished data. Jackson, N. J. Sci. Fd Agric. 1969,20,734. Miller, W. S.; Ewins, A.; Chubb, L. G. Vet. Rec. 1972, 91, 632. Hobson-Frohock, A.; Land, D. G.; Griffiths, N. M.; Curtis, R. F. Nature, Lond. 1973,243,304. Bolton, W.; Blair, R. Poultry Nutrition 1974, 4th ed., Bull. 174, London, HMSO, Ministry of Agriculture, Fisheries and Food.