composition of feather and offal meal and its value as a protein supplement in the diet of broilers

Composition of Feather and Offal Meal and its Value as a Protein Supplement in the Diet of Broilers by N. Jackson and R. B. Fulton Agricultitral Chemistry Department, Queen's University, Belfast, BT9 6BB and Poultry Department, Loughry Agricultrtral College, Cookstown, Co. Tyrone, Nortlierri Ireland

(Resised ,'Munuscript received 7 September, IY70)

Two experiments are described in which feather and osal meal was included at levels of 0, 3 .4 , 6 . 8 , 10.2, 13.6 and 17.07; in the diet of broilers. The feuther and onul meal WLIS irsed to replace Peruvian

Jishineal as the main protein source, the highest level replacing all of the Perirvian fishmeal. The feather and o f r l meal was poorer in lysitre and methionine content but richer in cystine than

Perrivian fishmeal. The batches used were relatively hrimo~~eneoia when assessed by chemical untrlysis unci Itrid metabolisable energy contents of 3350 arid 3340 kcal/kK, respectively.

Feed intake was depressed at the I7 level of inclusion of feather and of01 meal in the first e.vperinrent arid at the 13.6 "/, level in the second e.wperiment.

The data from both experiments showed an optimum efficiency of feed utilisafion at about the 10:4 level of'inclrrsion in the broiler diets.

Introduction THE econoniic use of animal protein supplements other than fishmeal and meat and bone meal in feedstuffs is of interest in animal production. Modern methods of poultry production and processing result in the availability of large quantities of feathers, viscera, heads, feet and blood. Considerable interest has been shown in the possible conversion of feathers and offal to a digcstible meal by steam pressure cooking.

The use of feather meal alone as a protein source in chick and broiler diets has been investigated by a number of workers.' fi They found that feather meal could be used in chick and broiler diets to supply approximately 25% of the protein requirement.

Ackcr et u I . , ~ have studied the nutrient composition of poultry offal and found the digestible protein t o be over 91 2, of the crude content for both unwashed and washed ofM. The washed material had a crude protein content of 17.7'j/, at a dry matter content of 27.9 04, the calciuni and phosphorus contents being 1 .8 :< and 1.3 0,; respectively. The product showed a considerable lack of homogeneity as assessed by protein analyses, the protein varying from 13.8 to 21 "/, for the sub-samples investigated. They suggested that in addi- tion to major nutrients, the vitamin content of fresh offal products might be of nutritional significance and that enzyme supplementation might increase the digestibility of dried blood and poultry feathers above the maximum reported value of 80":,.9.x

Romosers'zlo found that poultry by-products meal was a good protein source in broiler rations. A combination of hydrolysed feather meal, poultry by-product and poultry blood meal was also a satisfactory protein source. Wiseman ct ~ 1 . 1 ~ found hydrolysed feather meal, poultry by-products meal and poultry meal t o be satisfactory sources of animal protein in typical American grower, broiler and layers' rations when used to replace up to one-sixth of the crude protein content. Results with sub-optimum (17 % crude protein) grower diets indicated that the poultry by-product meal was lower in protein quality than fishmeal but comparable to meat scraps and soyabean oil meal.

Naber ct a/.'? found that when a poultry by-product meal that included blood, offal and feathers in their naturally occurring proportions was fed to supply 5 % protein in a chick diet, the diet had a higher nutritive value than diets containing feathcr meal.

Since American studies have shown that feather meal can be used t o replace a considerablc proportion of the protein in

poultry diets and that poultry by-product meal and poultry blood can also be used t o replace some of the crude protein in broiler and layers' rations, it was decided that the nutritive value of the feather and offal meal produced by a local manufacturer would merit investigation. Two experiments were carried out: experiment 1 at the Agricultural Research Institute, Hillsborough, Co. Down; and experiment 2 a t Loughry Agricultural College, Cookstown, Co. Tyrone.

Experimental In experiment I , 504 day-old female Ross 1 (broiler) chicks

were randomised into 24 groups each comprising 21 birds. The groups were then allocated t o 6 treatments, each with 4 replicates.

In experiment 2, 480 day-old ROSS 1 chicks comprising equal numbers of males and females were used. The males and females were each randomised t o 12 groups so that each group had 20 males and 20 females. These were then allocated t o the 6 treatments as for experiment I , each treatment being in duplicate.

In both experiments the 6 treatments consisted of a control diet having Peruvian fishmeal as the main protein source and 5 other diets in which the fishmeal was replaced by increasing amounts of feather and offal meal t o a maximum of 17%. The diets were calculated t o be isonitrogenous and isocaloric with respect t o metabolisable energy ( M E ) .

The meal was prepared by autoclaving feathers, offal and blood a t a pressure of 3 kg,'cmz and 135"c for 15 min. Cook- ing was then carried out for I f h at 93"c. At the end of this time the material was dried using steam and hot air.

The amino acid coniposition of the feather and offal meal and of the experimental diets was determined using a Tcch- nicon Auto-Analyzer. Available lysine in the feather and offal meal was determined by the method of Carpenter.lY The ME values of the diets were determined by the total collection method using three birds taken from each treatment a t the end of the 8-week experimental period. The M E of the feather and offal meal was also determined by the total collection method.

In both experiments the birds were floor-reared on new litter and fed mash ad libitum from tubular feedcrs. In experiment 1, 250 W infra-red heaters were used in each pen (floor area 5.4 m2) and 250 W canopy electric heaters (floor area 4 .8 m2) in experiment 2. Individual liveweight and group food consumption were recorded a t 2, 4, 6 and 8 weeks of age.

J. Sci. Fd Agric., 1971, Vol. 22, January

Jackson & Fulton: Feather and Offal Meal Composition and Value in Broiler Diets

TABLE I Proximate analysis and percentage amino acid composition of the feather and offal meal,

Peruvian fishmeal and meat and bone meal used in experiments 1 and 2'

39

Peruvian Meat meal fishmeal

Feather and offal meal

Experiment 1 Experiment 2

Crude protein (CP) , % Ether extract, % Gross energy, kcal/kg Standard M E , kcal/kg $apo,% r, /o

Dry matter, %

Alanine, % Arginine, % Aspartic acid, 76 Cystine, % Glycine, % Glutamic acid, % Histidine, % Isoleucine, % Leucine, % Lysine, % Methionine, % Phenylalanine, % Proline, "/, Serine, % Threonine, % Tyrosine, % Valine, "/, Lysine availability,

56.1 0.25 (lo)** 21.5 -!I 0 .24 (10) 5275 -- 57.6 (10) 3350 f 119 (4) 4 . 6 I 0.17 (10) 1 .3 -1- 0 . 02 (10) 93 .0

2.78 4 .22 3.71 3.98 4 .88 6.10 0 .63 2.46 3.98 2 .43 0.59 2 .64 4 .80 4.50 2.27 1.62 3.13

58

61.5 4- 0.17 110) 19.8 0 .14 (6)' 5310 1 4 8 . 3 (10) 3340 I: 73.5 (5) 2.1 _t 0.08 (10) 0 . 8 c 0.01 (10) 90 .0

3 .06 4 . 6 2 4 .16 3 .92 4 .83 6 .82 0 .82 2 .64 4 .86 2.78 0 .62 2.78 5.34 5 .26 2 .55 1.95 3.68

64

63 .4 - - - - - -

3.77 4.08 5.79 I .38 3 .60 8.12 1.18 2 ,76 4 .82 4 .92 I .83 2.79 2 .50 2.48 2.77 2.28 3 .12

90

50.9 - - - - - -

3.70 4.44 4 .89 3-1 I 4 .40 7.57 1.85 2.59 4.38 4 .54 1.20 2 .69 3.27 2.58 2.78 1.82 3.24

* Amino acids uncorrected for losses during acid hydrolysis ** Figures in parentheses are the number of samples on which the mean and standard errors are based

The proximate analyses of the feather and offal meals are given in Table I together with the determined M E values of the feather and offal meals. The amino acid compositions of the feather and offal meal used in each experiment and that of the Peruvian fishmeal and meat and bone meal used in both experiments are also given in Table 1.

The feather and offal meal was examined bacteriologically and the results are presented in Table 11.

In experiment 2, four males and four females from each pen were processed to give eviscerated weights and edible meat yields.

Results The compositions of the six experimental diets are presented

in Table 111 together with the proximate analysis, ME, calcium and phosphorus contents. The amino acid contents as percentage of the diets are presented in Table IV.

The initial liveweights and the liveweight, feed intake and efficiency of feed utilisation at 2, 4, 6 and 8 weeks of age are given in Tables V (experiment 1) and VI (experiment 2). The data in both experiments were subjected t o an analysis of variance.

Liveweight was affected by dietary treatments a t all ages in both experiments (P < 0.001) except a t 8 weeks of age in experiment 1 (P < 0.05).

At 4 and 6 weeks of age in experiment 1 the birds on treatment 6 were significantly lighter than those on the other five treatments (P < 0.001). In experiment 2 a t these ages the birds on treatments 5 and 6 were significantly lighter (P < 0*001) than those on the other treatments. In both experiments there were minor differences among treatments 1-4 a t 4 weeks of age but these were not present a t 6 weeks of age.

By 8 weeks of age in experiment 1 the birds on treatment 1 (no feather and offal nieal) were the lightest although not significantly lighter than those on treatment 6 (17% feather and offal meal). The latter treatment gave birds lighter than


TABLE I1 Results of bacteriological examination of feather and offal meals

Total counts/g MpN M P N

2 days 3 days ttltcfig Salmonella/ I00 g at 37"c at 22"c

- ___ Experiment 1 1,200 7,300 < I 0 Experiment 2 1,900 4,100 0 0

those on treatment 3 (P <0.05) and treatment 5 (P < 0.01). Birds on treatment 1 were lighter than those on treatment 3 (P < 0.05) and treatment 5 (P <0.01).

In experiment 2 there were no significant differences a t 8 weeks of age among treatments 1-4, all of which were significantly better than treatments 5 and 6. In experiment 2, differences between the sexes were significant (P < 0.001) at all ages except 2 weeks of age.

Taking the two experiments together it would seem that feather and offal meal prepared as described above can be used up t o a level of 10% as a replacement for Peruvian fishmeal without adversely affecting liveweight a t 8 weeks of age.

There was no significant influence on food intake at any age until the level of feather and offal meal reached 13.6% in experiment 2 and 17% in experiment 1. This suggests that feed intake is acceptable for all levels of feather and offal meal up t o 10%.

The results for efficiency of feed utilisation at 8 weeks of age are somewhat contradictory in the two experiments. In experiment I differences in efficiency are significant (P < 0.001) only a t 8 weeks of age, with efficiency improving with increasing levels of feather and offal meal. In experiment 2, differences are significant at all ages, with the tendency a t 8 weeks for efficiency t o deteriorate when the feather and offal meal content of the diets is increased.

40 Jackson & Fulton: Feather arid Offal Meal Composition and Value in Broiler Diets

TABLE 111

Composition of the six experimental diets

Diet No.

1 2 3 4 5 6

Maize meal Ground wheat Arachis oil Soyabean meal-extr. (44% CP) Feather and offal meal Peruvian fishmeal Meat meal Dicalcium phosphate Common salt Vitamin-mineral supplement * Total

Experiment 1 : Dry matter, % Standard M E , kcal/kg Crude protein, % Calorie : protein ratio Ether extract, % Crude fibre, ”/, Ca, % p, %

Experiment 2: Dry matter, % Standard ME, kcallkg Crude protein, % Calorie : Drotein ratio Ether extiact. ”/, Crude fibre, % - Ca, % p, %

5.00 65.75 2.50 7.00 0.00

15.00 3.75 0.50 0.00 0.50

100.00

87.9

22.2

5.4 2.5 1.2 0.7

3050

137

90.0

22.5

5 .6 2.1 1.3 0.9

3070

136

5.00 65.12 2.50 7.00 3.40

12.22 3.75 0.50 0.01 0.50

100.00

88.1

22.5

6.2 2.7 1.3 0.8

3130

139

90.0

22.7

5.5 2.1 1.2 0 .9

3170

I40

5.00 64.84

2.19 7.00 6.80 9.40 3.75 0.50 0.02 0.50

100.00

89.0

22.8

6.1 3.1 1.2 0 .7

3220

141

90.0

23.4

6 .2 1.9 1 . 1 0.8

3170

135

5 .00 64.95

I .87 7.00

10.20 6.20 3.75 0.50 0.03 0.50

100.00

88.9

22.1

6.0 2.8 1.2 0 .6

3330

151

90.0

23.8

6.8 2.4 1.0 0.8

3110

131

5.00 64.24

1.87 7.00

13.60 3.50 3.75 0.50 0.04 0.50

100.00

88.6

22.6

6.9 2 .9 1.3 0 .6

3240

143

90.0

21.6

6.4 2.0 0.9 0.7

3140

I45

5.00 63.38

I .87 7.00

17.00 0.00 4.70 0.50 0.05 0.50

100.00

88.9

22.3

7 .5 2.9 1.4 0.6

3320

149

90.0

23.5

6.9 2.1 0.9 0.7

3230

137

* Vitamin-mineral supplement supplied: 12 x lo6 I .U. vitamin A; 1.5 lo6 I.U. vitamin D3; 6.25 g vitamin E; 1.0 g vitamin K ; 1 .O g folic acid; 30 g nicotinic acid; 6.0 g pantothenic acid; 5.0 g riboflavin; 350 g choline chloride; 10 mg vitamin Bie; 14 g Cu; 77 g Mn; 57 g Zn; 2 g iodine; and 680 g DL-methionine per lo00 kg of diet. I t also contained a coccidiostat, an antioxidant and broad spectrum antibiotics

TABLE IV

Percentage amino acid composition of the diets in experiments I and 2*

Diet No.

1 2 3 4 5 6 ___-. ~ _ _ _ _ _ _ _ -

____ ~- __________ Feather and offal meal, % 0.0 3.4 6.8 10.2 13.6 17.0 Peruvian fishmeal, % 15.0 12.2 9.4 6.2 3.5 0.0

A Ian i ne 1.4 1.3 1 .3 1.2 1 . 1 1 .3 1.1 1.3 1 .1 1 . 2 1.0 1.3

___ ~ __ - -~ Expt. 1 Expt. 2 Expt. 1 Expt. 2 Expt. 1 Expt. 2 Expt. 1 Expt. 2 Expt. 1 Expt. 2 Expt. 1 Expt. 2

_.___-___ _ _ _ ~ _ _ ~ _ _ _

Arginine 1 .3 1.3 1.3 1.3 1.3 1.5 1.4 1.4 1.5 1.4 1.4 1 .6 Aspartic acid 1.8 1.9 1.8 1.9 1.5 1.9 1.7 1.9 1.6 1.7 1.5 1 .9 Cystine 0 . 6 0 . 6 0 .8 0 . 5 0.9 0.8 0.9 1.0 1.0 1.0 0.9 1.2 Glutamic acid 4.1 4 .2 4 .4 4.3 4.1 4.5 4 .0 4.3 4 .0 4.1 3 . 8 4.6 Glycine 1.4 1.5 1 .4 1.5 1 .5 1 . 5 1.5 1.7 1.5 1.6 1.6 1.8 Histidine 0.7 0.5 0.7 0.5 0 .6 0.7 0 .7 0.6 0.6 0.6 0.6 0.6 I soleuc i ne 1.0 1.0 1.1 0.9 1.0 1.0 1.0 1.1 1.0 1.0 1.0 1 . 1 Leucine 1.8 1.6 1.8 1.6 1.7 1.7 1.7 1.7 1.7 1.7 1.8 1.8

Methionine 0 . 4 0.5 0 .4 0.5 0 .3 0.4 0 .4 0.4 0 .3 0.3 0 . 3 0.3

Proline 1 .6 1.5 1.7 1.8 1.6 1.8 1.7 1.9 1.8 2.1 1.9 2.1 Serine 1.0 1.0 1 . 1 1 . 1 1.1 1.2 1.3 1.3 1.4 1.5 1.3 1.6 Threonine 0 .9 0.8 0 .9 0.8 0 .7 0.9 0.8 0.8 0.8 0.8 0.8 0 .9 Tyrosine 0.9 0 .8 0.9 0 .9 0 .8 0.9 0.8 0.9 0.8 0.8 0.8 0 .9 Valine 1 ’ 1 1.0 1.2 1 . 1 1 . 1 1 . 1 1.1 1.2 1.2 1.2 1.2 1.2

Lysine 1.4 1 .1 1 .3 1.2 1.4 1.2 1.2 1.1 1 .2 1.0 1.0 1 . 1

Phen ylalanine 1.2 1.1 1.2 1.1 1.1 1.2 1.1 1.2 1.1 1 .2 1.1 1 .3

* Amino acids uncorrected for losses during acid hydrolysis


Jackson & Fulton: Feather and Ofal Meal Composition and Value in Broiler Diets 41

In experiment 1 the processor graded the birds as follows: grade A, 91.8%; grade B, 6.7% and rejects, 1.4%; in experiment 2: grade A, 90.0%; grade B, 8 . 5 % and rejects, 1.5%.

The mortality in both experiments was 2% with no indication that it was affected by treatment.

tions on content, which assume satisfactory availabilities, are confirmed by the experimental data on growth rate, at least up to the 10% level of feather and offal meal inclusion. It is probably safe to assume that any inferior quality of feather and offal meal compared with fishmeal is due to differences in amino acid composition and possibly a somewhat lower nitrogen digestibility, i.e. a situation rather similar to that observed by Atkinson & Carpe11ter14-1~ for meat meals.

The data presented in Table 11 indicate that the samples of feather and offal meal used in these experiments were bacteriologically satisfactory. Obviously the control of time and temperature of cooking is vital if bacteriological quality is to be preserved without causing reduced availability.

Up to 6 weeks of age, growth rate was unaffected by increasing levels of feather and offal meal up to a level of 17 % in experiment 1 and 13.6% in experiment 2. This pattern was maintained at 8 weeks of age in experiment 2 whereas in experiment 1 the birds on the control diet failed to maintain the expected growth rate.

The pattern for feed intake in both experiments was similar, the intake being depressed at high levels of inclusion, this effect occurring at a lower level of inclusion in experiment 2 than in experiment 1 . A comparison of the amino acid contents of the diets (Table IV) with Combs,l6 requirements for broilers would suggest that lysine may be limiting at the higher levels of inclusion of feather and offal meal in the diets. This effect would be due to a combination of the fact that feather and offal meal is a poorer source of lysine than fishmeal, with the lower availability of lysine in the feather and offal meal. At the time of the experiment the factory pre- paring the feather and offal meal was not using an antioxidant and the possibility of an adverse effect due to ran- cidity cannot be ruled out. Unfortunately no analytical data are available to clear up this point. The data from both experiments show that there was a tendency for optimum

Discussion One difficulty in using material such as feather and offal

meal could be a lack of homogeneity of the product as found by Acker et aL7 However, in both experiments the analytical data for crude protein, calcium and phosphorus, based on ten samples, show that the material was relatively homogeneous.

The determined M E values of the diets were in fairly good agreement with the calculated values. The M E values ob- tained for the feather and offal meals were close to the value of 3480 kcal/kg assumed in designing the diets. The validity of these values was confirmed, particularly in experiment 2, by the reasonably good agreement between the experimentally determined dietary M E values and the calculated M E values which were in the range 306&3100 kcal/kg.

The amino acid data presented in Table I show that the feather and offal meals are poorer in their contents of lysine and methionine but richer in cystine than Peruvian fishmeal. In Tables I and IV no correction has been applied for the destruction of the amino acids during acid hydrolysis. It is assumed that this will have been considerably less in the high- protein materials than in the cereal-based diets. There are no other major differences in amino acid composition which are liable to have been of nutritional significance when the Peruvian fishmeal was replaced by the feather and offal meal in the broiler diets. It must be borne in mind that the amino acid data, with the exception of lysine, do not give any indication of their availability. However, the above observa-

1

,

TABLE V Mean liveweights, feed intakes and efficiency of feed utilisation at 0, 2, 4, 6 and 8 weeks of age (experiment 1)

Age, weeks ~~~

Feather and offal meal in diet, % 0 2 4 6 8

0.0 Mean liveweight, g Mean food intake per bird, g g food/g liveweight increase

Mean liveweight, g Mean food intake per bird, g g food/g liveweight increase







44.9 - -

44.8 -

263 359

1.65

629 1101

1.88

1103 2236

2.11

I099 2262

2.14

1102

1492 3564

2.46

1533 3588

2.41

I589 3664

2.37

1571 3459

2.27

1614 3650

2.34

1497 3357

i 2 8 . 8 1 6 3 . 8

2.31

i 0 . 0 3

3.7 3.6 2.3

3.4 265 385

1.75

620 1113

1.93

6.8 44.3 -

262 397

I .82

626 1133

1.95

615 1085

2251 2.13

10.2 44.3 - -

43.9 -

258 368

1077 21 56

2.09

1117

1.73 1.90

13.6 246 358

1.77

624 1127

1.94

~~~

2249 2.09

17.0 44.2

-

212 32 I

1.91

538 1016

2.05

995 2042

2.15

Standard error of a treatment mean

-i 14.3 '38.5

-1 0.03

Coefficient of variation

2.9 9 .3 9 . 1

2.7 4.1 4.1

2.6 3.5 2.4

~~ ~ ~ ~ ~~~~


42 Jockson & Fulton: Feather and Offal Meal Composition and Value in Broiler Diets

TABLE V I Mean liwveights, feed intakes and efficiency of feed utilisation at 0, 2, 4, 6 and 8 weeks of age (experiment 2)

Feather and Age, weeks offal meal in diet, 0 2 4 6 8

- _ _ ~ ____

- 0.0 Mean liveweight, g

3 .4

6 .8

10.2

13.6

17.0

Mean food intake per bird, g g food/g liveweight increase

Mean liveweight, g

Mean food intake per bird, g g foodlg liveweight increase

Mean liveweight, g

Mean food intake per bird, g g foodig liveweight increase

Mean liveweight, g

Mean food intake per bird, g g foodig liveweight increase

Mean liveweight, g

Mean food intake per bird, g g food/g liveweight increase

Mean liveweight, g

Mean food intake per bird, g g food!g liveweight increase

Mean average liveweight, g Mean for intake per bird, g

mean g food!g liveweight increase

Mean liveweight, g Mean food intake per bird, g

Standard error of a treatmcnt

Coefficient of variation g food/g liveweight increase

Male Female Average

Male Female Average

Male Female Average

Male Female Average

Male Female Average

Male Female Average

36

36

36

36

36

36

222 208 215 297

1.66

21 1 197 204 289

1.72

26 I 254 257 290

1.31

25 I 237 244 295

1.42

171 I65 168 253

I .94

150 136 143 247

2.31

18 .7 t 4 . 8 1.0.19

8 .5 2 .5

15 .1

655 595 625

1050 1.78

630 570 600

1015 1.80

632 584 608

1024 1.79

625 54 1 583

1018 I .86

449 427 438 898

474 430 452 868

2.23

2.09

15 .9 113.9 -C0.03

2.1 2 . 0 2 . 3

1132 984

1058 2159

2.11

I I96 1018 1 I07 2203

2.06

I130 lo00 1065 2128

2.07

I122 976

1049 2150

2.12

842 792 817

1872 2.40

904 804 854

I880 2.30

. 16.9 ._ - 16.3

10 .07

3 . 4 1 . 1 4 . 6

1636 1420 1528 3470

I698 1386 1542

2-33

3585 2.38

1600 I334 1467 3376

2.36

1681 I407 1544 3516

2.33

1378 1208 1293 3173

2.53

1440 I 200 1320 3168

2.47

t 3 3 . 0 ! 73.4

t 0.03

4 . 6 13. I

1 . 7

elficiency of feed utilisation to occur at the 10% inclusion of the feather and offal meal.

In experiment 2, mean da ta for evisccrdted weight and edible m a t yields showed n o significant effect of diet. Over all thc treatments the mean cviscerdted weight, excluding giblets, as a percentage of liveweight was 66.1 and the edible meat as a percentage of liveweight was 35 .1 .

Calculation of the relative cost per unit liveweight gain gave the following results for diets 1 to 6, respectively, when the data from both experiments were combined: 1.00, 0.99, 0.96, 0.91,0.95 and 0.93.

Taking the two experiments together, t he physical and economic da ta show that feather and offal meal can be used up t o a level of 10% as a replacement for Peruvian fishmeal in broiler diets.

Acknowledgments The authors wish t o thank the Trustees of the Agricultural

Research Institute, Hillsborough, and the Principal of Loughry Agricultural College for providing facilities for the broiler experiments; also colleagues in the Biometrics and Agricultural Bacteriology Departments. Thanks arc due t o Mr. W. H . Crawford, P. Poland, P. C. Liddle and R. M. Magowan for technical assistance.

I .

1 -.

3. 4.

5.

6.

7.

8.

9. 10. 1 1 .

12.

13. 14. 15. 16.

References

Gregory, B. K., Wilder, 0. H . M., & Ostby, P. C., Portlt. Sci., 1956, 35, 234 Kahle, H . S., & Gray, L. R., Mktg Res. Rep. No. 143, 1957 (U.S. Dem Arric.. Arric. Mktrr Serv.) McKerni, K.W.,'&Ritterspo;n, E., Poult. Sci., 1958, 37, 433 Sibbald, I . R., Slingcr, S. J., & Pepper, W. F., Poitlt. Sci., 1962, 41, 844 Tsang, S. T. L., McKee, F.. L., Andrews, G . P.. Winslade, C. E.. Steinhauser, R. L., & Windsor, H . A,. Porrlt. Sci., 1963,42, 1369 Summers, J. D., Slingcr, S. J., & Ashton, G . C. . Cun. J . Anim. Sci., 1965, 45, 63 Acker, R. F., Hartman, P. A., Pemberton, J. R., & Quinn, L. Y., Poult. Sci., 1959, 38, 706 Lortscher, L. L., Sachsel, G. F., Wilhelniy, O., & Fibert, R . B., Mktg Res. Rep. No. 181, 1957 (U.S. Dep. Agric., Agric. Mktg Serv.) Romoser, G . L., Proc. Univ. Maryland Nirtr. Con/., 1955, p. 41 Romoser, G. L., Proe. Univ. Marylrmd Ntrtr. Curif., 1956, p. 42 Wisman, E. L., Holmes, C . E., & Engel, R. W., Poitlt. Sci., 1958, 37, 834 Naber, E. C., Touchburn, S. P., Barnett, €3. D., & Morgan, C . L., Poult. Sci., 1961, 40, 1234 Carpenter, K. J . , Biuchern. J . , 1960, 77, 604 Atkinson. J . , &Carpenter, K. J. ,J . Sci. FdAaric., 1970, 21, 366 Atkinson, J., &Carpenter, K. J. . J . Sci. Fd'dgric., 1970,21. 373 Combs, G. F., 'The interrelationships of dietary energy and protein in poultry nutrition. Nutrition of pigs and poultry', 1962 (Eds. Lewis, D., & Morgan, J. T.) (London: Buttcrworth)


composition of feather and offal meal and its value as a protein supplement in the diet of broilers

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