3 rd International Poultry Conference 4 7 Apr Hurghada - Egypt

Transcription

1 EVALUATION OF COMMERCIAL LAYING HENS PERFORMANCE IN FLOOR PENS AND CONVENTIONAL CAGES UNDER SOUTH VALLEY CONDITIONS IN EGYPT. El-Sheikh, T. M. 1 and Ali, A. K. 2 1 Faculty of Agriculture, South Valley University, Sohag, Egypt 2 Assiut National Company for Poultry and Eggs. Abstract : A total of 9000 White and Brown laying hens were divided in to two groups: 4500 hens ( 2250 white in two replicates and 2250 Brown in two replicates too) were housed in battery cages with 5 hens per cage with a density of 690 cm2 per bird; the other 4500 hens were housed in intensive free range combined with a floor system and a density of 9 birds per m2 were used in this study. Egg number, egg weight, egg mass, mortality and rate of lay were recorded daily per group from 20 week until 73 week. At 20, 40 and 60 weeks of age 10 birds of each experimental replicate were visually assessed for the middle claw on both feet was measured with a dressmaker s tape. At 36 and 72 weeks 30 eggs were collected from each group. Eggs were individually weighed, then broken and the inner contents were placed on a leveled glass surface to determine yolk and albumen grade. Percentages of yolk, albumen and shell were calculated. Shell thickness was estimated by Ames shell thickness gauge. Yolk color scores were determined according to the La Roche scale (scores 1-15). Birds in cages had higher hen housed and hen day production by about 3.5 and 3.7%, respectively, than those in floor. The results regarding egg weight and egg mass per hen per day through 53 weeks of production were highly significant (P<0.001) in cages than in floor by about 2.2 gram and 4 grams egg mass per day, respectively. Daily feed consumption per hen was significantly (P<0.001) lower in cages than in floor by about 3.8 grams. Total feed conversion throughout 53 weeks production was the best in cages than floor, it was 2.08 vs kg feed/ kg eggs, respectively, the differences were significant (P <0.001). Mortality rate per week was significantly (P<0.05) higher in cages (0.25%) compared to floor (0.19%). Total mortality rate during the production period (53 weeks) was significantly increased by 3.41 % in cages (14.52 %) than those in floor (11.81 %). White hens were superior egg production in either hen day or hen housed production by

2 about 4.4 and 4.1 %, respectively, the differences were highly significant (P<0.01). No significant differences were observed in egg weight during 53 weeks of production between white and brown hens. White hens were consumed feed more than the brown hens by about 3.4 gram per hen per day kg/hen through the 53 weeks, respectively, the differences were significantly. Neither weekly feed conversion ratio nor FCR during 53 weeks were significant due to strain effect. Mortality rate of brown hens was significantly increased compared to white hens by about 0.07 % per week and 4.47 % throughout the 53 weeks production period. These findings indicate that brown strain is the best in cages than floor while white hens can produced good in floor. Claw length of caged birds was 24.9 mm compared to 20.5 mm of floor birds at 40 weeks the corresponding values were 30 mm vs mm at 60 weeks of age, while no significant differences were observed between white and brown hens at all ages. Eggs from hens which kept in floor were significantly increased in shell and yolk percentages as well as shell thickness and yolk color. Brown hen s egg showed higher shell %, yolk % and shell thickness. While white hens had higher albumen % as well as brighter yolk color than brown eggs. At both 36 and 72 weeks, eggs laid by brown hy-line had brighter yolk color and more blood spots (p<0.001) than white Hy-line. Eggs in cages had significantly brighter yolk color than the other system. The exterior egg quality measured did not seem to be affected by either housing system or hybrid. The higher proportions of dirty eggs were found in floor than cages. Egg broken in floor were lower than that in cages this may because the higher shell thickens as well as the handling egg collection from the nests. Key word: cages, floor, white and brown strains, egg production, egg quality, dirty eggs, claws

3 INTRODUCTION In several countries and in north-western Europe especially, there have been calls for cages to be banned and for hens to be kept in other kinds of systems to give them more space and the possibility to perform behaviors such as nesting, perching and using litter (Blokhuis and Metz, 1992; Craig and Swanson, 1994). The keeping of laying hens developed rapidly around the world during the 1960s and 1970s. In most developed countries today, about 90% of hens are kept in cages. Worldwide, it is estimated that 70 to 80% of flocks are caged. Although more floor housing systems are still in the growing countries and now being built in some European countries, the use of cages is increasing in developing countries (Bell, 1995). While there are several reasons for changing cages instead of keeping birds in flocks on floor, which include economic reasons as well as considerations of animal health and working environment. Cages allowed large unit to be built, and mechanization of production permitted considerably higher stocking densities and less investment and labor costs per weight of egg produced. Although there are several reasons for using floor systems in growing countries which include economic reasons such as the lowering salary of workers and the expensive of battery equipments as well consideration of animal welfare. Norgaard-Nielsen (1990) reported that keeping hens in cages thus restricts their movements, especially wing movements, to the degree that bone strength is greatly reduced. This has welfare implications, for hens with low bone breaking strength risk a possibility of breakage, especially when handled and transported. Gregory et al. (1991) found that weak bones and broken bones were more common in battery hens which had been reared to point of lay on deep litter rather than in cages. Eggs are the major business outputs in commercial table egg production and the higher the egg production the better will be the profit. Farooq et al (2001) found positive association of egg production with net profit in broiler breeders and reported major contribution of eggs in total returns. Commercial egg type layers started laying eggs at the age of weeks and produced 277 eggs till 72nd week of their production cycle according to Petek (1999). North (1984) found 266 and 257 number of eggs as hen-day, and hen-housed egg production during 52 weeks laying period for layers kept in cages. North (1984), Horne-Van and Van-Horne (1994) and Moorthy et al (2000) found better egg production performance of layers reared in cages than on

4 deep litter (floor rearing). Muthusamy and Viswanathan (1998) and Petek (1999) found higher egg laying performance of laying hens in cages than those kept on floor. The higher percent hen-day egg production in large sized flocks and hens kept in cages could be attributed to better management and rearing environment. Koelkebeck and Cain(1984) Egg production rates were greater for all caged hen treatments than for any floor or range groups. Koelkebeck et al. (1987) when they comparing all caged with floor pen hens, caged hens had better (P less than.05) egg production rates (76.3 vs. 73.9%), gained more weight. Pititte et al.(1982) found that initial egg production was similar for caged and floor housed hens, but the caged birds attained significantly higher egg production during peak production. Caged hens showed higher egg weight and body weight than the floor hens through the study. Interestingly, in the combined tests, the brown egg layers outperformed the white egg layers in the first egg production cycle by 4 eggs per hen-housed, but dropped behind in the second cycle by 13 eggs (Bell, 1998). Riczu et al. (2004) The white-egg strain produced 3.7% more marketable eggs during the experiment due to a 0.3 d shorter mean pause length in egg production. Feed consumption and its efficient utilization is one of the major concerns in commercial table egg production as feed cost is one of the major components of total cost of production. Feed alone may contribute from 60 to70% to the total cost of production in egg type layers according to Mian (1994) and Qunaibet et al (1992). Moorthy et al (2000) reported better efficiency of feed consumed by egg type layers kept in cages in India than those kept on deep litter. Anderson and Adams (1994) also reported higher feed consumption per bird among egg type layers maintained on the floor than those kept in cages. Koelkebeck and Cain (1984) reported that feed efficiency was poorer in floor and range groups compared to cages one. Koelkebeck et al. (1987) found that caged hens had better feed efficiency. Farooq et al. (2002) found that a smaller amount of layer ration was consumed by layers housed in cages than on the floor it was 30.6±0.62 vs. 32.8±0.97 and feed conversion was 1.9± 0.02 vs. 2.21±0.12, respectively. Anderson and Adams (1994) and Muthusamy and Viswanathan (1998) also reported smaller feed consumption/bird among layers kept in cages

5 than those kept on the floor. North (1984) reported that this was due to higher wastage of feed in floor systems than in cages. The brown egg layers consumed 6.8% more feed during the two cycles compared to the white egg layers. This was equivalent to 1.5 to 2.0 pounds of feed per 100 hens per day (Bell, 1998). Mortality in egg type chicken at any stage of life will affect performance of egg type layers; however, higher mortality during the laying period will badly affect productivity. A negative association of mortality with net profit in chicken production has been reported by Farooq et al (2001), Zaheer-ud-Din et al (2001) and Asghar et al (2000). Kitsopanidis and Manos (1991) also reported a reduction in net profit when mortality was more than 2-5%, whereas North (1984) reported poor economic performance of egg type layers at mortality level of more than 10%. Chew (1983) reported a mortality in layers ranging from 3.1 to 18%. Farooq et al (2002) found a lower mortality among flocks reared in cages than in those kept on the floor 2.29±0.16 vs. 7.57±0.95, respectively. Horne-Van and Van-Horne (1994) and North (1984) also reported higher mortality in flocks kept on the floor than those kept in cages. They attributed to poor litter management and greater disease risk. Coccidiosis during the laying period was higher in birds kept on the floor than in cages. On other hand; Koelkebeck et al. (1987) found that all floor pen hens had higher (P>0.01) viability (98.9 vs. 95.0%), higher (P >0.01) plasma corticosterone levels (595.0 vs pg/ml), a greater (P >0.01) response to adrenocorticotropin (ACTH) challenges, and lower (P >0.01) antibody titers to Salmonella pullorum challenges than all caged hens. A similar pattern for mortality was observed- reduced mortality during the first cycle, but a higher rate in the brown egg birds in the second cycle (Bell, 1998). Egg quality: Koelkebeck et al. (1987) found that caged hens had greater egg and egg shell weights than floor hens. Mench et al. (1986) Egg production was highest in (floor pens) and (cage) hens. There were no differences among treatment groups in feed efficiency, egg weight, although egg shell breaking strengths were lower in HD (cage) hens despite their relatively low egg production. Blood spots were most common in eggs from caged hens. Anderson and Adams (1994) found that hens reared in cages produced heavier (P <.001) eggs with a higher

6 percentage of grade A eggs and had fewer body checks than floorreared birds. Abrasives have not been found to effect egg quality (Tauson, 1986; Ruszler & Quisenberry, 1979 and Compton, et al., 1981) although Elson (1978) claims sharp toenails may cause shell damage especially in sagging cages where egg roll out is poor. Total cracks were 5 % with the claw shortener and 6.5 objects in a cage for laying hens must greatly increase the risk of % without the claw shortener (Elson, personal communication). the bird suffering from an abrasion. Both Glatz (2002) and Van Niekerk and Reuvekamp (2000) observed faeces on the abrasives. Riczu et al. (2004) Eggs from the brown strain were 3.4% heavier, had 4.0% more eggshell, and had a higher specific gravity than the white strain eggs (1.077 and 1.072, respectively). Final BW was 330 g greater in the brown-egg strain. These results indicate that this brownegg strain may be more resistant to weak and broken bones at the end of production than the white-egg strain. As expected, egg weight was significantly more in the brown egg birds and during the second cycle for both breeds. The net increase in weight averaged 4.4% for the brown egg birds over the white egg birds. Egg breakage was slightly higher in the second cycle compared to the first (2.8 vs 2.3%), but the breeds were quite comparable (Bell,1998). The significantly smaller percentage of shell for brown eggs, is associated with a lower yolk percent and a significantly higher albumen percent. As a result of higher albumen content, Haugh unit s measurements were 3.2 units higher in the brown shelled eggs (Bell, 1998). The claws are one of the most effective defensive structures, causing stress and altering behaviour patterns in other birds of the flock (Ruszler and Quisenberry, 1979). Hens in cages are not able to wear down their claws as effectively as free range birds or birds kept in other non-cage systems. Floor layers spend a great deal of their time foraging for food. This behaviour involves persistent scratching of the litter or soil looking for edible items such as insects, seeds, grain or vegetative material. The scratching behaviour wears down the claws and keeps them blunt. In cages, however, the claw length of the middle toe can reach over 40 mm (Hill, 1975; Tauson, 1977; Fickenwirth, et al., 1985) and in some strains the claws can become long, twisted, cracked and with a pronounced curl. Furthermore, even fairly short claws will still

7 get sharp and may also be a potential source of injury to other birds (Hill, 1975; Ruszler & Quisenberry, 1979; Fickenwirth, et al., 1985). The researchers were interested in determining the effects of various forms of management and housing on performance in white and brown egg strains of chickens. This research is, without a doubt, the most comprehensive ever attempted to seek answers to this very complex question. The present study aimed to investigate the ability of White and Brown commercial egg production and egg characteristics in deep litter compared to conventional cages. MATERIALS AND METHODS This study was carried out at the farms of Assiut national company for poultry and eggs during the period from October 2002 to November A factorial experimental design 2x2 was used in this study (2 housing systems, 2 types of commercial egg strains and two replicates of each). Birds and management The Hyline White and Brown strains of laying hen were obtained from a commercial pullet grower at 20 weeks of age. Previously birds were vaccinated against Marek's disease at hatching, infectious bronchitis at 4 days and again at 4 weeks, avian encephalomyelitis at 10 weeks and fowl pox at 12 weeks. A coccidiostat was provided to the birds via the ration during the rearing phase. The laying phase for this experiment commenced in October 2002 and continued through to November A total of 9000 Hyline White and Brown laying hens were divided in to two groups: 4500 hens ( 2250 white in two replicates and 2250 Brown in two replicates too) were housed in battery cages with 5 per cage with a density of 690 cm2 per bird; the other 4500 hens were housed in intensive free range combined with a floor system and a density of 9 birds per m2 were used in this study. Birds were distributed as follow:- Treatments Housing systems cages Deep litter Strains White Brown White Brown Replicates No of birds

8 The houses have fans ventilated insulated laying shed with louvred windows. The layer shed was equipped with evaporative coolers linked to a thermostat. The cooling operated when shed temperature at bird level reached. C 25 The temperature range in the shed during the experiment was approximately 25-35ºC. The layer diet was offered ad libitum as mash with birds having free access to water from nipple drinkers. Incandescent lighting was provided in the layer shed and was held constant at 16 h per day. Light intensity in the shed ranged from lux. Water was automatically available ad libtium. The maintenance and care management was the same for all birds and the same personnel were responsible for all keeping systems. 1- Production traits: Egg number, egg weight, egg mass and rate of lay were recorded daily per group from 20 week until 73 week. and Calculated as the hens day H.D.%, and hen housed H.H.% production as follow: H.D.% =[(Number of eggs produced/week)/(number of live hens)] x 100 H.H.% =[(Number of eggs produced/week)/(number of housed hens)] x 100 Feed conversion (FC: g feed/g egg). 3- Mortality was recorded daily and deaths as a result of injury, cannibalism and entrapment were noted as they occurred over the experimental period. 4- Claws: At 20, 40 and 60 weeks of age 10 birds of each experimental replicate were visually assessed for the middle claw on both feet was measured with a dressmaker s tape (tape-line or tape measure ) along the curvature of the claw. 5. Egg Quality Traits: At 36 and 72 weeks 30 eggs were collected from each group. Eggs were individually weighed, then broken and the inner contents were placed on a leveled glass surface to determine yolk and albumen grade. Percentages of yolk, albumen and shell were calculated. Shell thickness was estimated on the membraneless shells by Ames shell thickness gauge. Yolk color scores were determined according to the La Roche scale (scores 1-15). For exterior egg quality the mean of broken and dirty eggs was calculated. Following the collection period on each day the eggs were immediately assessed for shell faults. The faults recorded were waste or reject eggs due to shell faults that would render the eggs unfit for sale and consumption and dirty due to blood and faecal stains.before analysis, the traits given in proportions i.e. mortality, exterior egg quality were subjected to arcsin transformation (Snedecor & Cochran, 1968)

9 Statistical analyses Statistical analysis were conducted using the General Linear Models procedure of base SAS software (SAS Institute, 1997). Factors tested in analysis included housing systems, strain and housing by strain interactions. Percentages data of mortality were transformed to arcsine square root before mad the statistical analysis. Means were compared using Duncan s multiple range test (Duncan, 1955). Effect of housing systems RESULTS AND DISCUSSION The results of production are given in Table 1. There was a significant difference in production between cages and floor. Birds in cages had higher hen housed and hen day production by about 3.5 and 3.7%, respectively, than those in floor. Egg number either per week or through the season of production (53 weeks)was significantly higher in cages than those in floor by about 0.26, 14.1 eggs per hen, respectively. The results regarding egg weight and egg mass per hen per day through 53 weeks of production were highly significant (P<0.001) in cages than in floor by about 2.2 gram and 4 grams egg mass per day, respectively. So, the total increase in egg mass through the season was 1484 gram per hen in cages than those in floor. As presented in Table (2), it could be noticed that the daily feed consumption per hen was significantly (P<0.001) lower in cages than in floor by about 3.8 grams. The total feed consumption per hen during the 53 weeks production in cages was significantly (P<0.001) deceased by about Kg feed per hen. Weekly feed conversion was not significant differences between cages (2.39 gram feed/ gram egg) and floor (2.57 gram feed/ gram egg). While total feed conversion throughout 53 weeks production was best in cages than floor, it was 2.08 vs kg feed/ kg eggs, respectively, the differences were significant (P <0.001). The poor feed conversion ratio in floor may be due to the hand feeding, which resulted in higher feed levels in the trough and greater loss of feed due to flicking. Mortality rate per week was significantly (P<0.05) higher in cages (0.25%) compared to floor (0.19%). Total mortality rate during the production period (53 weeks) was significantly increased by 3.41 % in cages (14.52 %) than

10 those in floor (11.81 %). One of the original reasons for the claw length of birds in cages than those in floor (Table 3). North (1984), Horne-Van and Van-Horne (1994), Muthusamy and Viswanathan (1998) and Petek (1999) reported higher egg production of layers in cages than those kept on the floor. Higher hen-day and hen-housed egg production was found for White than Brown (Table 1). North (1984), Petek (1999) and Tolimir and Masic (2000) also found strain differences in hen-day and hen-housed egg production. Effect of strain: The effect of white and brown Hy-line types on egg laying performance are presented in Table (1), it could be observed that white hens were superior egg production in either hen day or hen housed production by about 4.4 and 4.1 %, respectively, the differences were highly significant (P<0.01). The egg number of white hens was significantly (P<0.001) either as weekly egg per hen or egg per 53 weeks production by about 2.7 and 15.9 eggs pr hen, respectively. No significant differences were observed in egg weight during 53 weeks of production between white and brown hens. These findings are disagreement with the findings of Bell (1998) and Riczu et al. (2004) who found that eggs from the brown strain were 3.4% heavier than white strain. This may be due to the lowering egg weight of brown eggs in floor house in the present study, while the results of Bell (1998) and Riczu et al. (2004) were due to the comparison between brown and white in cages for short period. On the other hand, white strain was significantly (P<0.001) higher daily egg mass based on gram egg per hen compared to brown strain by about 3.7 gram egg per hen day, this is may be due to the increasing of white egg number. This finding is a parallel with the findings of Abrahamsson and Tauson (1995) who reported that the light white Leghorn hybrids are in many ways quit different from brown hybrids, not only regarding live weight and some production properties but also regarding cannibalism and feather-peaking. As shown in Table (2) it could be reported that white hens were consumed feed more than the brown hens by about 3.4 gram per hen per day kg/hen through the 53 weeks, respectively, the differences were significantly

11 Neither weekly feed conversion ration nor FCR during 53 weeks were significant due to strain effect. Mortality rate of brown hens was significantly increased compared to white hens by about 0.07 % per week and 4.47 % throughout the 53 weeks production period. Effect of the interactions: The effect of interactions between housing systems and strains on hen day, egg number either per week or during 5 weeks production were significant (P<0.05). On the other hand, the hen housed production and egg weight as well as egg mass were not significantly affected by the interactions. In cages brown hens were increased hen day production but not significant, the opposite trend was observed on floor, therefore, the brown hens were significant lower egg production than the white. This finding indicate that that the white hens had more resistant in floor than brown hens. While brown hens had lower housed production than white hens in either cages or floor. This may be due to mortality increasing of white hens compared to brown hens. Results regarding egg number per hen per week, there were not significant differences in floor. White hens were had higher egg number than brown either in cages or in floor by about 6.2, and 25.6 eggs per hen throughout the 53 weeks production. Most significant differences regarding production were found between hybrids and were probably due to differences in their genetic capacity. However, it is interesting to note that there were interactions between hybrids and housing systems, which indicates that they are affected equally by the environment. The differences were not significant in egg mass between white and brown in cages, while it was significant in floor (Table 1). These findings indicate that brown strain is the best in cages than floor while white hens can produced good in floor. These findings are in agreement with the findings of Abrahamsson and Tauson (1993) who found that there was a significant interaction (P<0.02) between strain and cage design in laying percentage and egg weight. The same results were observed by Abrahamsson et al. (1995). No interaction were found between housing systems and hybrids in feed conversion, while there were significant interactions in feed consumption (Table 2). Daily feed consumption of white and brown is the same in cage, while in floor, white hens consumed significantly more than brown

12 There are a significant interaction (P<0.03) between housing systems and strain, hence the brown hens were significantly lower mortality than white hens in cages, the opposite trend was in the floor (Table 2). Incidence of broken eggs was higher on floor than in layers kept in cages (Table). Adams and Craig (1985) and Carey et al (1995) also found higher incidence of broken eggs in floor-reared laying hens than those kept in cages. The higher proportion of culled eggs on floor rearing could be attributed to poor management. Claw length: One of the criticisms of keeping birds in cages is the excessive length that claws can reach by the end of the laying period. Caged bird s claws grow to a considerable length and can be a source of injury to other birds. The middle claw length of hens from the two housing systems was significantly different (P<0.01) at40 and 60 weeks. The birds using the floor litter had the lowest claw length (Table 3) by the birds scratching their claws in the litter. It was observed that the claw length of caged birds was 24.9 mm compared to 20.5 mm of floor birds at 40 weeks the corresponding values were 30 mm vs mm at 60 weeks of age (Table 4). Caged bird s claws grow to 3-4 cm while for floor housed birds the claw length is kept shorter (about 1.5 cm) by the birds scratching their claws in the litter. One of the original reasons for reducing claw length with claw shorteners was to reduce mortality by minimising abrasions caused by the claws. Surprisingly hen mortality from prolapse and cannibalism was significantly higher in cages fitted with abrasives (Glatz, 2002b). The claws are one of the most effective defensive structures, causing stress and altering behaviour patterns in other birds of the flock (Ruszler and Quisenberry, 1979). Floor layers spend a great deal of their time foraging for food. This behaviour involves persistent scratching of the litter or soil looking for edible items such as insects, seeds, grain or vegetative material. The scratching behaviour wears down the claws and keeps them blunt. In cages, however, the claw length of the middle toe can reach over 40 mm (Hill, 1975; Tauson, 1977; Fickenwirth, et al., 1985) and in some strains the claws can become long, twisted, cracked and with a pronounced curl. Research in Europe on claw abrasives suggest that abrasives reduce claw length of hens, improves feather cover, lowers mortality and reduces the incidence of scratches and entrapment injuries (Glatz, 2002a). No significant differences were observed between white and brown hens at all ages. Highly significant differences were observed between the three

13 ages either in two housing systems or in two strains. The interaction between housing, strain and age of hens were not significant. Egg quality Significant differences in interior egg quality were found between eggs from cages and floor at different ages or between hybrids (white and brown). Eggs from hens which kept in floor were significantly increased in shell and yolk percentages as well as shell thickness and yolk color. The improving interior egg quality for laying hens in floor systems compared to cages battery may be due to the healthy case of hen bones. Birds are known to have stronger bones when allowed to exercise more (Norgaard-Nielsen, 1990). Gregory and Wilkins (1989) reported that 24% of hens suffered broken bones during depopulation. A limited area lead to soiling of plumage and varying egg quality (Tauson et al., 1992; Rauch, 1994). In housing systems with floors, hens spent 7 and 24% of their daytime activity scratching or pecking at the ground (Gibson et al., 1988; Appleby et al., 1989). Hens in common with other species of birds, will choose to forage for feed (Inglis and Ferguson, 1986) rather than eat identical feed which is freely available at feeder (Duncan and Hughes, 1972). Hens, therefore, appear to be highly motivated to forage in substrate such as that provided in more calcium and natural environment or littered floor. When deprived of litter, hens also redirect some of their groundpecking towards the feathers of other hens (Blockhuis and Arkes, 1984). Data presented in Table (6) shows that the differences between white and brown in interior egg quality were highly significant. Brown hen s egg showed higher shell %, yolk % and shell thickness. While white hens had higher albumen % as well as brighter yolk color than brown eggs. Riczu et al. (2004) Eggs from the brown strain were 3.4% heavier, had 4.0% more eggshell, and had a higher specific gravity than the white strain eggs (1.077 and 1.072, respectively). Scholtyssek et al. (1984) reported that there were several differences between hybrids in interior egg quality, they attributed this result to the differences of egg composition which is influenced by genotype of the bird and feed given, and probably to much lesser extent by the housing systems. At 36 weeks, there were significant differences between the two systems regarding interior egg quality. Shell %, shell thickness, yolk % and yolk color were increased significantly at the age of 36 weeks compared to

14 weeks of age. At both 36 and 72 weeks, eggs laid by brown hy-line were heavier (p< 0.05 at 36 weeks and p< 0.o1 at 72 weeks) and had lower albumen height, lower haugh units, brighter yolk color and more blood spots (p<0.001) than white Hy-line. At 72 weeks, eggs in cages were heavier than other eggs in deep litter (p<0.01). Eggs in cages also had significantly brighter yolk color than the other system. The exterior egg quality measured at the egg packing plant did not seem to be affected by either housing system or hybrid at all: not even the differences in egg shell thickness registered and it seemed to have any influence on proportions of broken eggs. The higher proportions of dirty eggs were found in floor than cages. This may be due to the fact that four to five eggs were laid in a nest of only 25 cm width could have caused greater risks of cleaning eggs. This problem could possibly be solved in practice by moving the egg collection belt a few times during the period of the day when most eggs are laid. Egg broken in floor were lower than that in cages this may because the higher shell thickens as well as the handling egg collection from the nests. This results is parallel with findings of Smith et al. (1993) who demonstrated that nests in cages have actually been reported to reduce both dirties and cracks when the eggs have been collected by hand from the nests. Another reason due to poor rolling out was probably affect the proportion of broken eggs. Eggs that do not roll out could increase the risk of egg-eating

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20 Table (1): Egg production performance of egg type laying hens as affected by housing systems and strain. Hen day Hen Egg/hen/ Egg/hen Egg % housed % week (20- weight Egg mass (g egg /h/d) 73wk) Housing system ** ** ** *** *** *** Cages (C) 79.2 a 75.5 a 5.54 a a 59.9 a 47.7 a Floor (F) 75.5 b 72.0 b 5.28 b b 57.7 b 43.7 b Strain ** ** *** *** NS *** White (W) 79.5 a 75.8 a 5.57 a a 58.8 a 47.1 a Brown (B) 75.1 b 71.7 b 5.26 b b 58.6 b 44.3 b Interaction * NS * *** NS ** Cages x White 78.3 a 76.5 a 5.60 a a 59.5 ab 47.9 a Cages x Brown 80.1 a 74.5 a 5.48 a b 60.2 a 47.4 a Floor x White 79.0 a 75.0 a 5.53 a b 58.2 bc 46.2 a Floor x Brown 72.0 b 69.0 b 5.04 b c 57.0 c 41.2 b abc Means with different subscripts in the same column under every factor were significantly different. NS = not significant, * significant P<0.05, ** significant P<0.01 and *** significant P<

21 Table (2): Effect of housing systems and strain on mortality, feed consumption and feed conversion. Mortal ity/wk mortalit y (20-73 wk) Feed consumpti on ( g f/h/d) Feed conversion g feed/g egg/week feed/hen kg (20-73wk) Feed conv. Kg f/kg egg (20-73wk) Housing system * *** *** NS *** * Cages (C) 0.25 a a 99.5 b 2.39 a b 2.08 b Floor (F) 0.19 b b a 2.57 a a 2.31 a Strain *** *** *** NS *** NS White (W) 0.18 b b a 2.41 a a 2.16 a Brown (B) 0.25 a a 99.7 b 2.55 a b 2.23 a Interaction * *** *** NS *** NS Cages x White 0.31 a c 98.9 b 2.32 a d 2.06 b Cages x Brown 0.18 b a b 2.45 a b 2.11 b Floor x White 0.18 b c a 2.49 a a 2.27 a Floor x Brown 0.20 b b 99.5 b 2.65 a c 2.36 a abc Means with different subscripts in the same column under every factor were significantly different. NS = not significant, * significant P<0.05, ** significant P<0.01 and *** significant P<

22 Housing Stain Table (3 ) Effect of housing systems, strain and age of hen on left and right claw length Housing Strain Age (week) Floor cages Brown White Right b a a a c b a Left b a a a c b a abc Means with different subscripts in the same row under every factor were significantly different. Table (4): Left and right foot claw length of birds at 20 weeks, 40 weeks and 60 weeks of age for white and brown hens in floor versus hens in cages. 20 wk 40wk 60wk Left Right Left Right Left Right Floor d d c c c c Cages cd cd b b a a Brown d c bc ab ab a White d c c b ab a abc Means with different subscripts in the same column under every factor were significantly different

23 Table (5 ): Effect of housing systems and strain on exterior egg quality Housing system Strain Interactions (Housing x strains) Floor Cages Brown White F x B F x W C x B C x W Dirty 7.07 a 3.63 b 5.31 a 5.35 b 6.89 a 7.18 a 3.73 b 3.52 a Broken a b a a b b a a Probability Housing Strain Interactions Dirty *** NS NS Broken *** NS NS abc Means with different subscripts in the same row under every factor were significantly different. NS = not significant, * significant P<0.05, ** significant P<0.01 and *** significant P<

24 Table (6): Effect of Housing, strain and age of hens on egg components, shell strength and yolk color. Variables Egg weight Albumen % Yolk % Yolk color Shell % Shell thickness Housing systems Floor 62.3 a 58.2 b 31.2 a 6.83 a a a Cages 64.5 b 60.4 a 29.8 b 6.48 b b b Strains Brown 63.9 a b a 6.52 b b a White 62.9 b a b 6.79 a 9.97 a a Age of hens 36 weeks 62.9 b b a 6.83 a a a 72 weeks 63.9 a a a 6.48 b 9.87 b b Probability Housing *** *** *** ** *** *** Strain ** ** ** * ** NS Age ** ** * ** *** * Housing X Strain NS NS NS NS NS NS Housing X Age NS NS NS NS NS NS Strain X Age NS NS NS NS NS NS Housing X Strain X Age NS NS NS NS NS NS abc Means with different subscripts in the same column under every factor were significantly different. NS = not significant, * significant P<0.05, ** significant P<0.01 and *** significant P<