British Poultry Science
ISSN: 0007-1668 (Print) 1466-1799 (Online) Journal homepage: http://www.tandfonline.com/loi/cbps20
Effects of high concentrations of dietary vitamin e and ethoxyquin on the performance of laying hens I. Bartov , Y. Weisman & E. Wax To cite this article: I. Bartov , Y. Weisman & E. Wax (1991) Effects of high concentrations of dietary vitamin e and ethoxyquin on the performance of laying hens , British Poultry Science, 32:3, 525-534, DOI: 10.1080/00071669108417377 To link to this article: http://dx.doi.org/10.1080/00071669108417377
Published online: 08 Nov 2007.
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Citing articles: 2 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=cbps20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 22:45
British Poultry Science (1991) 32: 525-534
EFFECTS OF HIGH CONCENTRATIONS OF DIETARY VITAMIN E AND ETHOXYQUIN ON THE PERFORMANCE OF LAYING HENS1 I. BARTOV2, Y. WEISMAN3 AND E. WAX2 Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
2
Department of Poultry Science, Agricultural Research Organization, The Volcani Center, P.O.B. 6, Bet Dagan 50250; and 3 Department of Avian Diseases, The Kimron Veterinary Institute, Bet Dagan, Israel Received for publication 19th June 1990
Abstract 1. Three experiments were carried out with light strain laying hens to evaluate the effects of relatively high doses of dietary vitamin E (125 mg/kg food) or ethoxyquin (EQ) (250 mg/kg food) on their laying performance. The control diet contained 5 and 125 mg/kg vitamin E and EQ, respectively. The experimental diets were fed either from one or 32 weeks until 88 or 89 weeks of age. 2. The two antioxidants did not affect the growth of the pullets, age at first egg, final body weight, average egg weight or relative abdominal fat pad size and liver weight at the termination of the experiments. In two out of three experiments, vitamin E and EQ did not affect egg production, food efficiency or mortality; in the third experiment vitamin E significantly ( P < 0.05) improved egg production and food efficiency after an outbreak of Newcastle disease which occurred at 34 weeks of age. EQ significantly reduced mortality during the course of this experiment, but did affect the variables of performance. In two experiments vitamin E consistently improved shell density, although a significant effect was observed in only one of the eight determinations carried out. EQ did not affect this variable. 3. The uterine muscle was more susceptible to oxidation than the drumstick meat, as evaluated by TBA values. In both tissues, vitamin E significantly and consistently decreased TBA values and restricted their increase during incubation, while EQ was less effective, particularly in the drumstick meat. 4. It is concluded that increasing vitamin E and EQ concentrations in diets of laying hens have no effect on the decrease in egg production due to aging. However, vitamin E may minimize the decline in eggproduction and food efficiency following the outbreaks of some diseases and slightly improve — under certain yet undefined conditions — shell density. 1 Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 3005-E, 1990 series.
525
526
I. BARTOV, Y. WEISMAN AND E. WAX
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
INTRODUCTION
Oxidation of lipids in the organism is an important factor in the aging process (Tappel, 1973). This oxidation results in the production and accumulation of the aging pigment, lipofuscin (Csallany et ah, 1977). Vitamin E and the synthetic antioxidant ethoxyquin (EQ) are known to have antioxidative activity, in vivo. Increasing vitamin E supplementation of the diet of rats reduced the amount of lipofuscin in their uteri (Csallany et al, 1984), protected their testes from degeneration resulting from old age (Hirahara et al., 1979a) and prevented the age-dependent decrease in nitrogen retention and blood protein (Hirahara et al., 1979b). Feeding mice on a diet containing 5-0 g EQ/kg increased their life span markedly (Comfort et al, 1971). Incorporation of EQ in diets of old laying hens prevented in part, the decrease in egg production (Charles and Romoser, 1980; Duke et al, 1978). On the other hand, elimination of vitamin E and antioxidant supplementation from the diets of 22-weekold laying hens did not affect laying performance, tensile strength of the eggs or mortality up to 73 weeks of age (Richter et al., 1985). The study reported here was carried out to investigate whether high concentrations of dietary vitamin E and EQ given to laying hens during various age periods may delay aging, as evaluated by their viability and egg production. MATERIALS AND METHODS
Birds
Day-old Leghorn X Rhode Island Red female chicks were obtained from a commercial hatchery. They were raised in electrically heated battery brooders in groups of 20 birds each up to 4 weeks of age, in grower cages in groups of 27 birds each up to 12 weeks of age and in individual layer cages in groups of 16 birds each. The grower and the layer cages were located in open sheds. In trials 1 and 3 birds were allocated to the dietary treatments at 32 weeks of age on the basis of egg production, body and egg weights and shell density (the latter variable was used only in trial 3). In trial 2 the birds were allocated to the dietary treatments at one week of age on the basis of body weight. Individual egg outputs were recorded daily. All eggs were weighed individually for 4 consecutive days at the end of each month. Body weights and food consumptions were also recorded at that time. Shell densities of all the eggs collected for weighing at the end of the month were determined two to five times during the course of each trial. Blood was taken from the brachial vein of 15 hens from each treatment, twice during the course of experiment 2, for determination of the titre of antibodies to Newcastle disease virus (NDV). Eight hens, which represented the treatment in their body and egg weights, as well as in egg production, were sacrificed at the end of trials 1 and 2 to determine their relative fat pad size, liver weight and the antioxidative status of the drumstick meat and the uterus. The latter was determined by the thiobarbituric acid (TBA) test, which gives information on the amount of lipid oxidation byproducts accumulated in the tissue (fresh or after storage) or produced after additional incubation under controlled conditions.
ANTIOXIDANTS FOR LAYING HENS
527
TABLE 1
Composition of the starter (0 to 6 weeks), grower (7 to 18 weeks), and layer (18 to 89 weeks) diets
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
Diet
Starter
Grower
Layer
Ingredients (g/kg) Sorghum 619-87 694-0 438-64 Maize , 200-0 Soyabean meal (450 g protein/kg) 318-0 170-0 247-0 0-5 DL-Methionine 0-63 1-86 Wheat bran 15-0 87-0 Dicalcium phosphate 20-0 18-0 16-0 Limestone 10-0 14-0 80-0 Constant ingredients' 16-5 16-5 16-5 Calculated composition (/kg) Metabolisable energy (MJ) 11-92 11-92 11-48 Crude protein (g) 201-0 152-0 169-0 9-2 Calcium (g) 10-0 35-4 7-3 6-9 6-0 Phosphorus (g) 1 Acidulated soyabean soapstock, 10-0; mineral mix, 4-0; vitamin mix, 2-5. The compositions of the vitamin and trace minerals mixtures have been described by Bartov el al. (1988).
Vaccination
Each bird was vaccinated against Newcastle disease (ND) by an eye drop with 107 EID50 of live vaccine (B.L.T. Biological Labs, Jerusalem, Israel) at the age of 10 d followed by subcutaneous inoculation of 0'5 ml inactive vaccine (B.L.T. Biological Labs) at the age of 17 d. Blood samples were taken periodically from the birds for the determination of the titre of antibodies to NDV. Whenever the titre was lower than 4-2, the birds were reinoculated with 1-0 ml of the inactive vaccine.
Diets
Practical diets containing 5 mg vitamin E and 125 mg EQ/kg were used as controls during the various age periods (Table 1). These diets were fed as such or supplemented either with additional vitamin E (dl-a-tocopheryl acetate) or EQ. Experimental procedure
Experiments 1 and 2. The basal diets or diets supplemented with extra vitamin E or EQ (120 and 125 mg/kg) were fed to 32-week-old hens or to one-week-old chicks up to 88 or 89 weeks of age in experiments 1 and 2, respectively. Experiment 3. The experiment was carried out during the period 32 to 88 weeks of age. Hens were fed on the basal diet or the diet supplemented with vitamin E (120 mg/kg). The latter was provided at 32, 45 or 58 weeks of age.
528
I. BARTOV, Y. WEISMAN AND E. WAX TABLE 2
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation on performance of laying hens from 32 to 88 weeks of age (experiment 1) Antioxidant supplement (mg/kg diet) Variable
None
E, 120
EQ, 125
SEM1
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
2
Weight gain (g) 177 21-6 143 162 Eggs/hen housed 3 288 276 299 1-0 Eggs/100 hen d2 73-7 75-7 0-6 73-8 2 Egg weight (g) 65-7 65-5 66-1 0-4 Food efficiency (g/egg) 2 136 140 140 2-5 Shell density (mg/crn2)4 at 67 weeks of age 72-6 75-0 75-0 0-9 at 80 weeks of age 70-6 71-5 1-1 70-2 at 88 weeks of age 68-3 71-0 71-6 1-2 Mortality and degeneration (%) 8-4 3-6 4-2 4-2 1 Standard error of the mean. 2 Data based on three groups of 13-16 birds in each treatment. The variables of performance are averages of 13 periods, each of about 30 d. 3 During 396 d. 4 Average of 38-48 hens/treatment, 1-3 eggs/hen.
TABLE 3
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation on TBA values of the drumstick meat and the uterine tissue (experiments 1 and 2) TBA values1 Drumstick meat Experiment
Antioxidant supplement (mg/kg diet)
Initial level2
After incubation 3
Uterine tissue Initial level2
After incubation 3
45-0" 32-6' 85-8» 2-7a 13-9b 6-0b 18-2b 3-3» f a 21-4 70-8* 4-0 51-9" SEM4 0-9 5-3 2-3 8-6 2 None 72-6» 95-2» 5-9a 31-1' E, 120 8-41' 10-l b 21-6 b l-7 b EQ, 125 13-9'> 29-6" 3-8* 50-2 a 9-6 0-9 SEM 9-7 2-7 1 Expressed as sodium salt of malonaldehyde bis-bisulphite (mg/kg) dry tissue. Values are means of eight birds. Means without a common superscript differ significantly ( P < 0 0 5 ) . 2 After 38 and 70 d of storage at — 18°C, in experiments 1 and 2, respectively. 3 In water bath at 37°C for 1 h under constant shaking. 4 Stardard error of the mean. 1
None E, 120 EQ, 125
Chemical and biological analyses
Shell weight was determined after drying the washed shell in an forced-air oven at 105°C overnight. TBA test was performed after frozen storage, as described by Machlin et al. (1959), except for the use of cold water during homogenisation (Desai and Scott, 1966). The developing colour was related to a standard curve of malonaldehyde bis-bisulphite sodium salt, prepared according to Saslaw and Waravdekar (1957) and expressed as mg/kg dry tissue. The determination of the status of antibodies to NDV in the sera was performed by
529 the beta micro haemagglutination-inhibition (HI) test, essentially as described by the National Research Council (1971). The NDV antigen was adjusted by dilution to contain four units of haemagglutination activity. ANTIOXIDANTS FOR LAYING HENS
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
85-
eSg 75O * 70"
P S 65P
^
a so • 5045-
240220200180-
Q o O
160140 120
x x i x n i
n m r v v v i V n v n i i x x x i x n i DATE (month)
FIG.—Effect of supplementation of antioxidants (none, • • ; vitamin E, A A; ethoxyquin, • • ) to diets of laying hens, on egg production (upper panel) and food efficiency (lower panel). Data based on three groups of 13-16 birds in each treatment. The first period of egg production is of two weeks, starting at 5 months of age (experiment 2).
Calculation and statistical analyses
Shell density (mg/cm2) was computed from the weight of the dried shell and the surface area calculated according to Mueller and Scott (1940). Means were subjected to analysis of variance (Snedecor and Cochran, 1967) and to a multiple range test (Duncan, 1955).
530
I. BARTOV, Y. WEISMAN AND E. WAX
RESULTS
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
Experiment 1
The two antioxidants did not affect weight gain and viability (mortality and degeneration) or any of the variables of performance (Table 2). The relative sizes of the abdominal fat pads and livers were also not affected by the treatments (32-41 and 21-23 g/kg body weight, respectively). Vitamin E significantly reduced initial TBA values in the uterus and also reduced the increase in TBA values in the uterus and the drumstick meat during incubation (Table 3). EQ was much less effective than vitamin E in its influence on initial TBA values in the uterus and had no effect on their increase after incubation in both tissues.
TABLE 4
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation to diets fed from 7 days of age, on performance of laying hens from 19 to 89 weeks of age (experiment 2)
Antioxidant supplement (rag/kg diet) Variable None E, 120 EQ, 125 SEM1 2 Weight gain (g) 326 342 316 35 Eggs/hen housed3 291 330 318 14 2 b a Eggs/100 hen d 65-5 71-9 66-8" 2-9 Egg weight (g)2 64-5 65-1 64-8 0-7 Food efficiency (g/egg)2 157" 141b 156J 2-0 Shell density (mg/cm2)4 at 24 weeks of age 78-3 79-5 78-4 0-7 at 49 weeks of age 75-0 76-3 75-0 1-3 at 65 weeks of age 69-8b 73-6a 71-2ab 1-1 at 79 weeks of age 69-2 71-9 69-5 1-4 at 88 weeks of age 68-5 71-2 70-2 1-6 2 a al) Mortality (%) 14-6 6-2 2-1" 3-4 1 Standard error of the mean. 2 Data based on three groups of 13—16 birds in each treatment. The variables of performance are averages of 16 periods (15 periods for food efficiency), each of about 30 d (15 d for the first period of egg production). Means without a common superscript differ significantly (P
ISSN: 0007-1668 (Print) 1466-1799 (Online) Journal homepage: http://www.tandfonline.com/loi/cbps20
Effects of high concentrations of dietary vitamin e and ethoxyquin on the performance of laying hens I. Bartov , Y. Weisman & E. Wax To cite this article: I. Bartov , Y. Weisman & E. Wax (1991) Effects of high concentrations of dietary vitamin e and ethoxyquin on the performance of laying hens , British Poultry Science, 32:3, 525-534, DOI: 10.1080/00071669108417377 To link to this article: http://dx.doi.org/10.1080/00071669108417377
Published online: 08 Nov 2007.
Submit your article to this journal
Article views: 15
View related articles
Citing articles: 2 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=cbps20 Download by: [NUS National University of Singapore]
Date: 06 November 2015, At: 22:45
British Poultry Science (1991) 32: 525-534
EFFECTS OF HIGH CONCENTRATIONS OF DIETARY VITAMIN E AND ETHOXYQUIN ON THE PERFORMANCE OF LAYING HENS1 I. BARTOV2, Y. WEISMAN3 AND E. WAX2 Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
2
Department of Poultry Science, Agricultural Research Organization, The Volcani Center, P.O.B. 6, Bet Dagan 50250; and 3 Department of Avian Diseases, The Kimron Veterinary Institute, Bet Dagan, Israel Received for publication 19th June 1990
Abstract 1. Three experiments were carried out with light strain laying hens to evaluate the effects of relatively high doses of dietary vitamin E (125 mg/kg food) or ethoxyquin (EQ) (250 mg/kg food) on their laying performance. The control diet contained 5 and 125 mg/kg vitamin E and EQ, respectively. The experimental diets were fed either from one or 32 weeks until 88 or 89 weeks of age. 2. The two antioxidants did not affect the growth of the pullets, age at first egg, final body weight, average egg weight or relative abdominal fat pad size and liver weight at the termination of the experiments. In two out of three experiments, vitamin E and EQ did not affect egg production, food efficiency or mortality; in the third experiment vitamin E significantly ( P < 0.05) improved egg production and food efficiency after an outbreak of Newcastle disease which occurred at 34 weeks of age. EQ significantly reduced mortality during the course of this experiment, but did affect the variables of performance. In two experiments vitamin E consistently improved shell density, although a significant effect was observed in only one of the eight determinations carried out. EQ did not affect this variable. 3. The uterine muscle was more susceptible to oxidation than the drumstick meat, as evaluated by TBA values. In both tissues, vitamin E significantly and consistently decreased TBA values and restricted their increase during incubation, while EQ was less effective, particularly in the drumstick meat. 4. It is concluded that increasing vitamin E and EQ concentrations in diets of laying hens have no effect on the decrease in egg production due to aging. However, vitamin E may minimize the decline in eggproduction and food efficiency following the outbreaks of some diseases and slightly improve — under certain yet undefined conditions — shell density. 1 Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 3005-E, 1990 series.
525
526
I. BARTOV, Y. WEISMAN AND E. WAX
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
INTRODUCTION
Oxidation of lipids in the organism is an important factor in the aging process (Tappel, 1973). This oxidation results in the production and accumulation of the aging pigment, lipofuscin (Csallany et ah, 1977). Vitamin E and the synthetic antioxidant ethoxyquin (EQ) are known to have antioxidative activity, in vivo. Increasing vitamin E supplementation of the diet of rats reduced the amount of lipofuscin in their uteri (Csallany et al, 1984), protected their testes from degeneration resulting from old age (Hirahara et al., 1979a) and prevented the age-dependent decrease in nitrogen retention and blood protein (Hirahara et al., 1979b). Feeding mice on a diet containing 5-0 g EQ/kg increased their life span markedly (Comfort et al, 1971). Incorporation of EQ in diets of old laying hens prevented in part, the decrease in egg production (Charles and Romoser, 1980; Duke et al, 1978). On the other hand, elimination of vitamin E and antioxidant supplementation from the diets of 22-weekold laying hens did not affect laying performance, tensile strength of the eggs or mortality up to 73 weeks of age (Richter et al., 1985). The study reported here was carried out to investigate whether high concentrations of dietary vitamin E and EQ given to laying hens during various age periods may delay aging, as evaluated by their viability and egg production. MATERIALS AND METHODS
Birds
Day-old Leghorn X Rhode Island Red female chicks were obtained from a commercial hatchery. They were raised in electrically heated battery brooders in groups of 20 birds each up to 4 weeks of age, in grower cages in groups of 27 birds each up to 12 weeks of age and in individual layer cages in groups of 16 birds each. The grower and the layer cages were located in open sheds. In trials 1 and 3 birds were allocated to the dietary treatments at 32 weeks of age on the basis of egg production, body and egg weights and shell density (the latter variable was used only in trial 3). In trial 2 the birds were allocated to the dietary treatments at one week of age on the basis of body weight. Individual egg outputs were recorded daily. All eggs were weighed individually for 4 consecutive days at the end of each month. Body weights and food consumptions were also recorded at that time. Shell densities of all the eggs collected for weighing at the end of the month were determined two to five times during the course of each trial. Blood was taken from the brachial vein of 15 hens from each treatment, twice during the course of experiment 2, for determination of the titre of antibodies to Newcastle disease virus (NDV). Eight hens, which represented the treatment in their body and egg weights, as well as in egg production, were sacrificed at the end of trials 1 and 2 to determine their relative fat pad size, liver weight and the antioxidative status of the drumstick meat and the uterus. The latter was determined by the thiobarbituric acid (TBA) test, which gives information on the amount of lipid oxidation byproducts accumulated in the tissue (fresh or after storage) or produced after additional incubation under controlled conditions.
ANTIOXIDANTS FOR LAYING HENS
527
TABLE 1
Composition of the starter (0 to 6 weeks), grower (7 to 18 weeks), and layer (18 to 89 weeks) diets
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
Diet
Starter
Grower
Layer
Ingredients (g/kg) Sorghum 619-87 694-0 438-64 Maize , 200-0 Soyabean meal (450 g protein/kg) 318-0 170-0 247-0 0-5 DL-Methionine 0-63 1-86 Wheat bran 15-0 87-0 Dicalcium phosphate 20-0 18-0 16-0 Limestone 10-0 14-0 80-0 Constant ingredients' 16-5 16-5 16-5 Calculated composition (/kg) Metabolisable energy (MJ) 11-92 11-92 11-48 Crude protein (g) 201-0 152-0 169-0 9-2 Calcium (g) 10-0 35-4 7-3 6-9 6-0 Phosphorus (g) 1 Acidulated soyabean soapstock, 10-0; mineral mix, 4-0; vitamin mix, 2-5. The compositions of the vitamin and trace minerals mixtures have been described by Bartov el al. (1988).
Vaccination
Each bird was vaccinated against Newcastle disease (ND) by an eye drop with 107 EID50 of live vaccine (B.L.T. Biological Labs, Jerusalem, Israel) at the age of 10 d followed by subcutaneous inoculation of 0'5 ml inactive vaccine (B.L.T. Biological Labs) at the age of 17 d. Blood samples were taken periodically from the birds for the determination of the titre of antibodies to NDV. Whenever the titre was lower than 4-2, the birds were reinoculated with 1-0 ml of the inactive vaccine.
Diets
Practical diets containing 5 mg vitamin E and 125 mg EQ/kg were used as controls during the various age periods (Table 1). These diets were fed as such or supplemented either with additional vitamin E (dl-a-tocopheryl acetate) or EQ. Experimental procedure
Experiments 1 and 2. The basal diets or diets supplemented with extra vitamin E or EQ (120 and 125 mg/kg) were fed to 32-week-old hens or to one-week-old chicks up to 88 or 89 weeks of age in experiments 1 and 2, respectively. Experiment 3. The experiment was carried out during the period 32 to 88 weeks of age. Hens were fed on the basal diet or the diet supplemented with vitamin E (120 mg/kg). The latter was provided at 32, 45 or 58 weeks of age.
528
I. BARTOV, Y. WEISMAN AND E. WAX TABLE 2
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation on performance of laying hens from 32 to 88 weeks of age (experiment 1) Antioxidant supplement (mg/kg diet) Variable
None
E, 120
EQ, 125
SEM1
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
2
Weight gain (g) 177 21-6 143 162 Eggs/hen housed 3 288 276 299 1-0 Eggs/100 hen d2 73-7 75-7 0-6 73-8 2 Egg weight (g) 65-7 65-5 66-1 0-4 Food efficiency (g/egg) 2 136 140 140 2-5 Shell density (mg/crn2)4 at 67 weeks of age 72-6 75-0 75-0 0-9 at 80 weeks of age 70-6 71-5 1-1 70-2 at 88 weeks of age 68-3 71-0 71-6 1-2 Mortality and degeneration (%) 8-4 3-6 4-2 4-2 1 Standard error of the mean. 2 Data based on three groups of 13-16 birds in each treatment. The variables of performance are averages of 13 periods, each of about 30 d. 3 During 396 d. 4 Average of 38-48 hens/treatment, 1-3 eggs/hen.
TABLE 3
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation on TBA values of the drumstick meat and the uterine tissue (experiments 1 and 2) TBA values1 Drumstick meat Experiment
Antioxidant supplement (mg/kg diet)
Initial level2
After incubation 3
Uterine tissue Initial level2
After incubation 3
45-0" 32-6' 85-8» 2-7a 13-9b 6-0b 18-2b 3-3» f a 21-4 70-8* 4-0 51-9" SEM4 0-9 5-3 2-3 8-6 2 None 72-6» 95-2» 5-9a 31-1' E, 120 8-41' 10-l b 21-6 b l-7 b EQ, 125 13-9'> 29-6" 3-8* 50-2 a 9-6 0-9 SEM 9-7 2-7 1 Expressed as sodium salt of malonaldehyde bis-bisulphite (mg/kg) dry tissue. Values are means of eight birds. Means without a common superscript differ significantly ( P < 0 0 5 ) . 2 After 38 and 70 d of storage at — 18°C, in experiments 1 and 2, respectively. 3 In water bath at 37°C for 1 h under constant shaking. 4 Stardard error of the mean. 1
None E, 120 EQ, 125
Chemical and biological analyses
Shell weight was determined after drying the washed shell in an forced-air oven at 105°C overnight. TBA test was performed after frozen storage, as described by Machlin et al. (1959), except for the use of cold water during homogenisation (Desai and Scott, 1966). The developing colour was related to a standard curve of malonaldehyde bis-bisulphite sodium salt, prepared according to Saslaw and Waravdekar (1957) and expressed as mg/kg dry tissue. The determination of the status of antibodies to NDV in the sera was performed by
529 the beta micro haemagglutination-inhibition (HI) test, essentially as described by the National Research Council (1971). The NDV antigen was adjusted by dilution to contain four units of haemagglutination activity. ANTIOXIDANTS FOR LAYING HENS
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
85-
eSg 75O * 70"
P S 65P
^
a so • 5045-
240220200180-
Q o O
160140 120
x x i x n i
n m r v v v i V n v n i i x x x i x n i DATE (month)
FIG.—Effect of supplementation of antioxidants (none, • • ; vitamin E, A A; ethoxyquin, • • ) to diets of laying hens, on egg production (upper panel) and food efficiency (lower panel). Data based on three groups of 13-16 birds in each treatment. The first period of egg production is of two weeks, starting at 5 months of age (experiment 2).
Calculation and statistical analyses
Shell density (mg/cm2) was computed from the weight of the dried shell and the surface area calculated according to Mueller and Scott (1940). Means were subjected to analysis of variance (Snedecor and Cochran, 1967) and to a multiple range test (Duncan, 1955).
530
I. BARTOV, Y. WEISMAN AND E. WAX
RESULTS
Downloaded by [NUS National University of Singapore] at 22:45 06 November 2015
Experiment 1
The two antioxidants did not affect weight gain and viability (mortality and degeneration) or any of the variables of performance (Table 2). The relative sizes of the abdominal fat pads and livers were also not affected by the treatments (32-41 and 21-23 g/kg body weight, respectively). Vitamin E significantly reduced initial TBA values in the uterus and also reduced the increase in TBA values in the uterus and the drumstick meat during incubation (Table 3). EQ was much less effective than vitamin E in its influence on initial TBA values in the uterus and had no effect on their increase after incubation in both tissues.
TABLE 4
Effect of vitamin E (E) and ethoxyquin (EQ) supplementation to diets fed from 7 days of age, on performance of laying hens from 19 to 89 weeks of age (experiment 2)
Antioxidant supplement (rag/kg diet) Variable None E, 120 EQ, 125 SEM1 2 Weight gain (g) 326 342 316 35 Eggs/hen housed3 291 330 318 14 2 b a Eggs/100 hen d 65-5 71-9 66-8" 2-9 Egg weight (g)2 64-5 65-1 64-8 0-7 Food efficiency (g/egg)2 157" 141b 156J 2-0 Shell density (mg/cm2)4 at 24 weeks of age 78-3 79-5 78-4 0-7 at 49 weeks of age 75-0 76-3 75-0 1-3 at 65 weeks of age 69-8b 73-6a 71-2ab 1-1 at 79 weeks of age 69-2 71-9 69-5 1-4 at 88 weeks of age 68-5 71-2 70-2 1-6 2 a al) Mortality (%) 14-6 6-2 2-1" 3-4 1 Standard error of the mean. 2 Data based on three groups of 13—16 birds in each treatment. The variables of performance are averages of 16 periods (15 periods for food efficiency), each of about 30 d (15 d for the first period of egg production). Means without a common superscript differ significantly (P
