




































In ternationa l
Scholars
Journa ls

 

African Journal of Pig Farming ISSN 2375-0731 Vol. 5 (9), pp. 001-005, September, 2017. Available online at 
www.internationalscholarsjournals.org © International Scholars Journals 

 

Author(s) retain the copyright of this article. 

 

Full Length Research Paper 

 

Utilization of sun-dried on-farm generated poultry 
litter as a feed resource for growing-finishing pigs 

 
A. O. K. Adesehinwa*, O. O. Obi, B. A. Makanjuola, A. O. Adebayo and E. S. Durotoye 

 
Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M.B. 5029, Moor Plantation, Ibadan. 

Nigeria. 
 

Accepted 12 April, 2017 
 
Forty eight (48) growing-finishing pigs (36.11 ± 1.26 kg) were allotted to three dietary treatment groups of 0, 
33.33 and 66.67% sun-dried on-farm generated poultry litter (SOPL) as a replacement for 30% maize in diets of 
growing-finishing pigs on weight basis to assess its implication on the chemical composition of the feed, 
growth performance and blood chemistry of the pigs. Each treatment was replicated four times with 4 
pigs/replicate in a completely randomized design. The diets were formulated to contain 16 - 19% crude protein 
and the pigs housed in concrete floored pens containing feeding and watering troughs for the duration of the 
study. The results obtained in this study revealed some numerical differences in the crude protein and fibre 
contents of the SOPL diets over the control diet. Increases were also recorded in the acid detergent fibre 
(ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL) fractions of the diets as a result of the 
replacement levels of SOPL. Daily weight gains and the efficiency of feed utilization of the growing pigs were 
not significantly (P > 0.05) influenced by the graded levels of SOPL. Replacement of maize with 33 and 66% 
SOPL resulted in 10.4 - 20.9% reduction in the cost of feed/kg. This in turn resulted in 15 - 25% reduction in the 
cost of feed required for an additional kg gain/pig when the graded levels of SOPL was fed to the pigs. An 
increased level of up to 66% SOPL resulted in a depression (P < 0.05) in the values of packed cell volume 
(PCV) and white blood cells (WBC) while the hemoglobin, serum glucose, urea, creatinine and glutamate 
pyruvate transaninase values of the pigs across the groups were unaffected (P > 0.05). However, variations 
recorded in the values of the red blood cells (RBC) and alkaline phosphatase did not follow any particular 
trend. The values of the serum total protein, albumin and cholesterol values increased significantly (P < 0.05). 

 
 Key words: Acid detergent fibre, neutral detergent fibre, acid detergent lignin, sun-dried on-farm generated poultry litter. 

 
 
 
INTRODUCTION 

 
Research results of over 45 years in Virginia Polytechnic 
Institute and State University, Blacksburg, Virginia, United 
States, on the nutritional value of feeding  
 
 
 
*Corresponding author. E-mail: aokadesehinwa@yahoo.com. 
 
Abbreviations: TDN, Total digestible nutrient; SOPL, sun-dried 
on-farm generated poultry litter; ADF, acid detergent fibre, NDF, 
neutral detergent fibre; ADL, acid detergent lignin; PCV, packed 
cell volume; WBC, white blood cells; ALT, alanine 
transaminase; GPT; glutamate pyruvate transaminase; AIBPs, 
agro-industrial by-products; PKC, palm kernel cake; IAA, 
indispensable amino acids; Hb, haemoglobin. 

 
 
 
 
 

 
poultry litter, performance of cattle fed litter, animal health 
status, quality of animal products and studies on residues 
in animal products have been satisfactory, with no toxic 
effect on the cattle. About 20 - 25% of the 5.6 million tons 
of poultry litter (dry matter) produced annually in the U.S. 
is fed to beef cows and stock cattle in Virginia (Fontenot 
and Hancock, 2001). It was reported to be a rich source 
of essential minerals, with a crude protein content of 
between 25-50 and 55-60% total digestible nutrient (TDN) 
on dry matter basis, while the nutritional value was rated 
as similar to or higher than good quality legume hay. 
Dehydration, with or without pelleting, has also been 
reported to be a satisfactory process, if the cost is not too 
high. 



 
 
 

 

Poultry litter includes excreta, bedding (mainly wood 
shavings in Nigeria), wasted feed and feathers (Fontenot 
and Hancock, 2001). Hence it represents a vast reservoir 
of cheap nutrient. Good management, including exclusion 
of dead birds/ other extraneous materials from the litter 
and appropriate processing prior to feeding, such as sun 
drying has been reported to prevent growth of micro-
organisms (Fontenot and Hancock, 2001).  

However, even in the face of the incidence of Avian 
Influenza, on-farm generated poultry litter in farms where 
integrated system is practiced, with no reported disease 
cases could be a potential cheap source of feedstuff for 
growing-finishing pigs. In recent years, the use of animal 
manure for livestock feeding has generated considerable 
interest due to the fact that the conventional feedstuffs 
can no longer adequately meet the need of the fast 
growing livestock industry (Abeke et al., 2003).  

Poultry waste has been successfully used in ruminant 
rations in Egypt. The total bacterial count was consider-
ably lower in sun dried poultry waste compared to the 
oven dried waste. Aflatoxins were not detectable in the 
concentrate mixtures containing poultry litter (Makkar, 
2002). Both feed intake and milk production in ewes was 
not affected by the inclusion of 14% poultry waste as a 
dietary supplement, suggesting that cottonseed meal and 
other high protein feed ingredients could be, at least 
partially replaced, by poultry waste without any loss in 
productivity. The weight and age at puberty of lambs fed 
a ration containing 17% poultry waste was similar to 
those given a ration without any poultry waste. Similarly, 
poultry waste up to 20% in the diet had no detrimental 
effect on growth in cattle and buffaloes and on the 
reproductive performance in buffalo heifers evaluated.  

The inclusion of 15% poultry waste in mixed concentrate 

feed decreased the cost of feed by about 10% (Makkar, 
2002).  

It is noteworthy that a number of farmers are already 
involved in the use of poultry litter/manure in the feeding 
of pigs in some parts of Nigeria. There is therefore the 
need for the right technology/package for the use of 
poultry litter as a feedstuff for growing pigs. The study 
was designed to investigate the effect of sun-dried on-
farm generated poultry litter (SOPL) (from a stock of 
growing pullets on the farm) as a replacement for maize 
in diets of growing-finishing pigs on the growth perfor-
mance, some carcass traits, serum metabolites and 
heamatological indices in an attempt to reduce feeding 
cost using non-conventional feed resources. 
 

 
MATERIALS AND METHODS 
 
On-farm generated poultry litter was processed by sun-drying in 
continuous sunlight (10-12 h/day) for three days during the dry 
period of the year (late November -late January) to a constant 
moisture content of 12% before being incorporated into the 
experimental diets.  

Forty eight (48) growing-finishing pigs (36.11 ± 1.26 kg) were 
asigned to three dietary treatment groups of 0, 10 and 20% SOPL 

 
 
 
 

 
Table 1. Gross composition of test diets fed to growing-finishing 
pigs. 
 

Ingredients 0% SOPL 33% SOPL 66% SOPL 

Maize 30.0 20.0 10.0 

SOPL 0.0 10.0 20.0 

Palm kernel cake 30.0 30.0 30.0 

Wheat offal 18.0 18.0 18.0 

Groundnut cake 15.0 15.0 15.0 

Fish meal (65%) 3.0 3.0 3.0 

Bone meal 2.25 2.25 2.25 

Oyster shell 1.0 1.0 1.0 

Salt 0.50 0.50 0.50 

Premix* 0.25 0.25 0.25 
 
*Pfizer agricare grower premix supplied the following per kg diet: Vit. A 

10,000,000 IU; Vit. D3 2,000,000 IU; Vit. E 8,000 IU; Vit. K 2,000 mg; 

Vit. B1 2,000 mg; Vit. B2 5,500 mg; Vit. B6 1,200 mg; Vit. B12 12 mg; 
biotin 30 mg; folic acid 600 mg; niacin 10,000 mg; pantothenic acid 
7,000 mg; choline chloride 500,000 mg; Vit. C 10,000 mg; Iron 60,000 
mg; Mn 80,000 mg; Cu 8,00 mg; Zn 50,000 mg; iodine 2,000 mg; cobalt 
450 mg; Selenium 100 mg; mg 100,000 mg and Anti oxidant 6,000 mg. 
 

 

(as a replacement for 0, 33.33 and 66.67% of the 30% maize 
content) in diets of growing-finishing pigs, on weight basis (Table 
1). Each treatment was replicated four times with 4 pigs/ replicate in 
a completely randomized design. The diets were formulated to contain 16 
- 19% crude protein (Table 2) and the pigs housed in concrete 
floored pens containing feeding and watering troughs for the 
duration of the study. The pigs were allowed ad libitum access to 
the diets and water, served in concrete feeding and watering 
troughs, respectively. The growth performance and economy of 
production were monitored throughout the 42-day duration of the 
trial.  

Proximate compositions of the test ingredients (SOPL) and 

experimental diets, as well as separation of fibre fractions were 

done according to the methods of A.O.A.C. (1990). Blood sample 
was randomly collected from 2 pigs/ replicate for the three treatment groups 

at the end of the feeding trial and analyzed for serum metabolites and 

hematological parameters. The bleeding was done in the morning 

before feeding and 10 ml of blood was obtained from the jugular vein 
into two sample bottles using a sterilized needle and syringe as 

described by Adesehinwa (2007).  
The samples for the serum were allowed to clot before 

centrifuging to obtain the serum used in the determination of some 
serum metabolites (serum protein, albumin, glucose, cholesterol, 
creatinine, urea and hepatic serum enzyme activities of alanine 
transaminase (ALT), glutamate pyruvate transaminase (GPT) and 
alkaline phosphatase) using commercial kits of Span Diagnostics, 
Surat, India (Tripathi et al., 2008). The haematological attributes 
were estimated in whole blood just after bleeding, using standard 
procedures (Jain, 1986). Data generated on growth performance, 
serum metabolites and hematological parameters of the pigs were 
subjected to statistical analysis using SAS Computer software 
package (SAS, 1991). 

 

RESULTS AND DISCUSSION 
 
Chemical analysis 
 
Proximate composition of the sun-dried on-farm poultry 
(growing pullets) litter (SOPL) used in the study is 



  
 
 

 
Table 2. Proximate composition of SOPL and experimental diets. 

 

Parameters 0% SOPL 33% SOPL 66% SOPL SOPL 

Dry matter (%) 88.59 88.65 88.72 88.61 

Crude protein (%) 16.58 19.67 19.85 23.76 

Crude fibre (%) 6.52 7.29 7.37 11.22 

Ether extract (%) 3.51 3.69 3.75 3.49 

Ash (%) 7.46 8.21 8.46 13.15 

NDF (%) 34.97 49.77 51.28 42.68 

ADF (%) 15.87 31.24 33.54 22.87 

ADL (%) 5.12 13.58 13.76 8.77 
 

 
Table 3. Performance, carcass and cost of feed conversion growing-finishing pigs. 

 

Parameters 0% SOPL 33% SOPL 66% SOPL SEM (±) 

Daily feed intake (kg) 1.39 1.44 1.37 0.07 

Daily weight gain (kg) 0.42 0.46 0.44 0.02 

Feed: Gain 3.32 3.12 3.11 0.13 

Cost of feed consumed/day (N) 40.07
a
 39.13

a
 33.27

b
 0.82 

% Reduction in cost of feed consumed - 2.35 16.97 - 

Cost of Feed/Weight Gain (N/kg) 105.35
a
 90.09

b
 78.94

b
 4.23 

% Reduction in cost of feed/ Gain - 14.48 25.06 - 

Dressing percentage (%) 67.71 67.25 65.80 0.78 

Back fat Thickness (cm) 2.35 2.28 2.38 0.11 
 

$1 (US dollar) = N150.00 (Nigerian Naira). 
 

 

shown in Table 2. Slight increases were observed in the 
crude protein and fibre contents of the SOPL diets over 
the control diet. Aro and Tewe (2007) reported a high 
fibre content for the dried poultry waste fed to barrows, 
while the higher protein content (23.76%) of the test 
ingredient (SOPL) could be responsible for the higher 
values obtained for diets containing SOPL compared to 
the maize-control diet. However, the crude protein of the 
litter used in this study was slightly lower than the range 
reported by Fontenot and Hancock (2001) for broiler 
birds.  

Increases of about double were recorded in the acid 
detergent fibre (ADF), neutral detergent fibre (NDF) and 
acid detergent lignin (ADL) fractions of the diets as a 
result of the replacement levels of the SOPL (Table 2). 
This could be said to be in agreement with the findings of 
Aro and Tewe (2007), who reported high indigestible 
component even though the fibre fractions were not 
separated in their study with dried poultry waste for 
barrows. This is expected, taking into consideration the 
fact that wood shavings, which is generally used as 
beddings in Nigeria is a highly fibrous material, being a 
by-product of the wood processing industry. Heat treated 
sheep dropping inclusion in broiler finisher diet was 
reported by Onu and Otuma (2008) to result in increased 
crude fibre content with a resultant dilution in the energy 
values. 

 
 

 

Growth performance 
 

Daily weight gains and the efficiency of feed utilization 
(feed: gain) of the growing pigs were not significantly (P > 
0.05) influenced by the graded levels of SOPL (Table 3). 
The performance results of the pigs fed with the waste 
(SOPL) was similar to that of the maize-based control. 
However, the values obtained in this study were lower 
compared to the range of 550 - 610 g reported by Aro 
and Tewe (2007). Processing of poultry litter (inclusive of 
sun-drying as obtained in this study) has been reported 
to destroy potential pathogens, improve handling and 
storage characteristics, as well as enhance palatability 
(Fontenot and Hancock, 2001), hence, its efficient 
utilization, as also shown in the findings of this study. 
There was no mortality recorded throughout the study 
period.  

The cost of feed consumed per day for the 66% SOPL 
inclusion was significantly (P < 0.05) lowered by 17% 
when compared with the control diet (33% SOPL). The 
resultant effect of the diets on the pigs in terms of cost 
per kilogramme gain in body weight was lowered by 15 
and 25% at the two inclusion levels respectively. Phillip 
(1984) reported that reducing feed cost was not only to 
obtain cheaper feed, but was also dependent on the 
production result obtained with this cheaper feed. The 
efficiency with which the feed was utilized was that which 



 
 
 

 
Table 4. Hematological indices of growing-finishing pigs fed graded levels of SOPL. 

 

Parameters 0% SOPL 33% SOPL 66% SOPL SEM (±) 

Packed cell volume (PCV) % 37.63
a
 36.13

ab
 34.50

b
 0.61 

Hemoglobin (Hb) g/dl 11.93 11.30 10.60 0.29 

Red blood cell (RBC) x 10
6
/µl 805.00

a
 648.75

b
 736.25

ab
 31.67 

White blood cell (WBC) x 10
3
/µl 395.75

a
 336.00

ab
 251.25

b
 24.93 

 

 

was of major importance (Phillip, 1984).  
The results obtained in this study is a pointer to the 

achievement of the objective of this study to reduce the 
cost of finishing pigs using agro-industrial by-products 
(AIBPs) or wastes. The dressing % and back-fat 
thickness were not significantly (P > 0.05) influenced by 
the increasing levels of SOPL in comparison to the 
maize-based control diet (Table 3). This is in agreement 
with the findings of Fontenot and Hancock (2001) who 
reported feeding of broiler litter not to adversely affect the 
carcass quality as observed in this study. The dressing % 
observed in this study was slightly lower compared to the 
values obtained by Aro and Tewe (2007). This may not 
be unconnected with the fact that a higher level of maize 
content (between 52 - 55%) was used in the diets utilized 
in this study. It should be noted that the SOPL was 
employed in this study to replace maize as against its 
replacement of palm kernel cake (PKC) in their study, 
noting that PKC has higher fat content compaed to 
maize. 
 

 

Blood analysis 

 

Hematology and blood biochemistry are routinely used in 
veterinary medicine to evaluate the health status of 
animals and poultry (Mafuvadze and Erlwanger, 2007). 
An increased level of SOPL up to 66% (that is, 20% 
SOPL inclusion) resulted in a decrease (P < 0.05) in the 
values of packed cell volume (PCV) and white blood cells 
(WBC) while the hemoglobin (Hb) values of the pigs 
across the groups were unaffected. The inclusion of 
SOPL up to this level seemed to have reduced the values 
of the PCV and WBC. Fluctuation in erythrocyte count, 
hematocrit (PCV) and hemoglobin concentration have 
been reported to be considerable during the growing 
period of the pig (Mitruka and Rawnsley, 1977). Varia-
tions recorded in the values of the red blood cells (RBC) 
did not follow any particular trend (Table 4). The value 
observed for the 66% SOPL was comparable to those of 
pigs on the control diet.  

The influence of diets on haema-tological and serum 
biochemical variables have been established (Ologhobo 
et al., 1993; Otesile et al., 1991; Olorede et al 1995). 
Dietary protein quality is dependent upon the adequacy 
and balance of the ten indispensable amino acids (IAA). 
A deficiency of one or more of the IAA will not only result 
in poor growth and other productive functions but may 

 

 

also lower disease resistance (NRC, 1979). The urea 
values observed were comparable across the groups, as 
such, the animals could not have suffered muscular 
wastage but an efficient utilization of the diets, thereby 
resulting in high tissue deposition (Adesehinwa, 2004) 
across the groups. This result showed that the protein 
levels in the diets were able to support normal protein 
reserves in the pigs resulting from efficient protein 
utilization (Adesehinwa, 2007).  

Reduction in concentrations of erythrocytic parameters 
(such as PCV, RBC counts and Hb concentration) and 
elevation in MCV are indications of macrocytic (regene-
rative) anaemia emanating from increased destruction 
and subsequent enhanced erythropoiesis in the liver, 
spleen and kidneys (Jain, 1986). However, the results 
obtained in this study were within the safe range reported 
in literature for this class of pigs (Mitruka and Rawnsley, 
1977).  

The serum glucose, urea, creatinine and glutamate 
pyruvate transaninase values were unaffected by the 
treatment. However, the serum total protein, albumin and 
cholesterol values were increased while alkaline phos-
phatase did not follow any trend (Table 5). Protein 
deficiency has been reported to reduce most haemato-
logical and serum parameters (Jain, 1986) through reduced 

or impaired synthesis of blood cells which are largely 
proteinaceous. Serum urea and creatinine levels in 
animals are indicative of muscular wastage (Fashina, 
1991). Higher urea and creatinine values may be brought 
about by the inadequacy or unavailability of the dietary 
protein, poor digestibility or inefficient utilization of the 
protein (Adesehinwa and Ogunmodede, 2004), but this 
was not reflected in the overall performance of the pigs 
used in this study.  

With these results, it is obvious that with good manage-
ment, feeding SOPL has no adverse effect on the health 
status of the pigs, taking into consideration the results of 
the serum metabolites and hematological indices 
observed in this study. Rather it is beneficial for the 
poultry industry by helping to reduce the over-application 
of poultry litter to the soil which possibly results in high 
levels of nitrogen and phosphorus in soil water (Dilger et 
al., 2004). 
 

 

Conclusion 

 

From the above results, it could be inferred that  growing- 



  
 
 

 
Table 5. Serum metabolites of growing-finishing pigs fed graded levels of SOPL. 

 

Parameters 0% SOPL 33% SOPL 66% SOPL SEM (±) 

Total protein (g/dl) 5.20
b
 7.05

a
 6.25

ab
 0.38 

Albumin (g/dl) 3.98
b
 4.20

b
 5.63

a
 0.27 

Glucose (mg/dl) 48.08 45.20 49.03 6.22 

Cholesterol (mg/dl) 87.48
ab

 72.78
b
 101.20

a
 4.84 

Urea (mg/dl) 22.73 20.90 16.80 2.61 

Creatinine (mg/dl) 0.88 1.18 1.48 0.13 

GPT (IU/L) 7.33 6.18 6.25 0.38 

Alkaline phosphatase (IU/L) 36.35
a
 22.73

c
 28.40

b
 1.90 

 

 

finishing pigs can tolerate the replacement of up to 66% 
of the 30 kg maize fraction of the diet (that is, 20 kg) with 
sun-dried on-farm poultry litter (SOPL) without any 
adverse effect on the performance, cost of feed 
conversion and the overall health status of the pigs. 
 

 
REFERENCES 
 
Abeke FO, Ogundipe SO, Sekoni AA, Adeyinka IA, Abubakar BY, Oni 

OO, Nwagu BI (2003). Response of Laying Hens to Dietary Levels of 
Heat Treated Sheep Manure (HSM). Trop. J. Anim. Sci. 6: 111-116.  

Adesehinwa AOK (2007). Utilization of palm kernel cake as a 
replacement for maize in diets of growing pigs: effects on 
performance, serum metabolites, nutrient digestibility and cost of feed 
conversion. Bulg. J. Agric. Sci. 13: 593-600.  

Adesehinwa AOK (2004). Implications of feeding high levels of maize 
offal as energy source on the growth and costs of feed conversion of 
growing pigs. J. Food, Agric. Environ. 2(3and4): 95-98.  

Adesehinwa AOK, Ogunmodede BK (2004). Performance and serum 
metabolites of growing pigs fed diets containing “Dusa” and cashew 
nut testa as protein sources. Indian J. Anim. Sci. 74(1): 3-6. 

AOAC (1990). Official methods of analysis (15
th

 Ed). Association of 
Official Analytical Chemists, Arlington, V.A.  

Aro SO, Tewe OO (2007). Performance and carcass yield of barrows 
fed dried poultry waste as a replacement for palm kernel cake. Afr. J. 
Biotechnol. 6(4): 487-492.  

Dilger RN, Onyango EM, Sands JS, Adeola O (2004). Evaluation of 
microbial phytase in broiler diets. Poult. Sci. 83: 962-970.  

Fashina HA (1991). Utilization of soybean based rations by grower and 
finisher pigs in hot humid tropics Ph. D Thesis, University of Ibadan. 
Nigeria.  

Fontenot JP, Hancock JW (2001). Utillization of poultry litter as feed for 
beef cattle. Paper presentation at FDA Public Hearing, Kansas city, 
MO, October 30, 2001, on Animal feeding regulation Animal Protein 
Prohibited in Ruminant Feed- Code of Federal Regulations, Titled 21 
Part 589, 2000.  

Jain NC (1986). Schalm’s Veterinary Haematology, 4
th

 edn. Lea and 
Febiger, Philadelphia, PA, pp. 225-239. 

 

 
Mafuvadze B, Erlwanger KH (2007). The effect of EDTA, heparin and 

storage on the erythrocyte osmotic fragility, plasma osmolality and 
haematocrit of adult ostriches (Struthio camelus). Vet. Arhiv. 77: 427-
434.  

Makkar HPS (2002). Development and field evaluation of animal feed 
supplementation packages (AFRA PROJECT 11-17 - RAF/5/041) - 
Project summary. Joint FAO/IAEA Division of Nuclear Techniques in 
Food and Agriculture/International Atomic Energy Agency p. 6.  

Mitruka BM, Rawnsley HM (1977). Chemical biochemical and 
heamatological reference values in normal experimental animals. 
Masson, N.Y. 

National Research Council (NRC) (1979). Nutrient requirements for 

domestic animals. 2. Nutrient Requirement for swine. 8
th

 Rev. Edn. 
National Acad. Press, Washington DC.  

Ologhobo AD, Apata DF, Oyejide A, Akinpelu RO (1993). A comparison 
of protein fractions prepared from Lima beans (Phaseolus lunatus) in 
starter diets for broiler chicks. J. Appl. Anim. Res. 4: 13-30.  

Olorede BR, Ajagbonna OP, Babatunde GM (1995). Comparism of air-
dried poultry dropping in broiler rations: Effect on performance, organ 
weight and haematological parameters. Int. J. Anim. Sci. 10:289-293.  

Onu PN, Otuma MO (2008). Utilization of Heat-Treated Sheep Dropping 
in the Diets of Broiler Finisher Chicks. Int. J. Poult. Sci. 7(2): 169-173.  

Otesile EB, Fagbemi BO, Adeyemo O (1991). The effect of 
Trypanosoma brucei infection on serum biochemical parameters in 
boars on different planes of dietary energy. Vet. Parasitol. 40: 207-
216. 

Phillips GD (1984). Feed utilization: Principles and new developments in 
Physiology. Can. J. Anim. Sci. 64: 543-549.  

SAS Institute (1991). SAS® User’s Guide: Statistics. Version 6.03 
edition. SAS Institute, Inc., Cary., NC.  

Tripathi MK, Mondal D, Karim SA (2008). Growth, haematology, blood 
constituents and immunological status of lambs fed graded levels of 
animal feed grade damaged wheat as substitute of maize. J. Anim. 
Physiol. Anim. Nutr. 92: 75-85. 


