Effects of egg size (weight) and age on hatching performance and chick quality of broiler breeder

Transcription

1 Journal of Applied Animal Research ISSN: (Print) (Online) Journal homepage: Effects of egg size (weight) and age on hatching performance and chick quality of broiler breeder Javid Iqbal, Sohail Hassan Khan, Nasir Mukhtar, Tanveer Ahmed & Riaz Ahmed Pasha To cite this article: Javid Iqbal, Sohail Hassan Khan, Nasir Mukhtar, Tanveer Ahmed & Riaz Ahmed Pasha (2016) Effects of egg size (weight) and age on hatching performance and chick quality of broiler breeder, Journal of Applied Animal Research, 44:1, 54-64, DOI: / To link to this article: Taylor & Francis Published online: 06 Dec Submit your article to this journal Article views: 8392 View related articles View Crossmark data Citing articles: 3 View citing articles Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 25 December 2017, At: 14:57

2 Journal of Applied Animal Research, 2016 Vol. 44, No. 1, 54 64, Effects of egg size (weight) and age on hatching performance and chick quality of broiler breeder Javid Iqbal a, Sohail Hassan Khan b *, Nasir Mukhtar a, Tanveer Ahmed c and Riaz Ahmed Pasha d a Department of Poultry Science, Faculty of Veterinary and Animal Sciences, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan; b Poultry Research Institute, Rawalpindi, Pakistan; c Department of Livestock Production and Management, Faculty of Veterinary and Animal Sciences, Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan; d Department of Veterinary Basic Sciences, Faculty of Veterinary and Animal Sciences, Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan (Received 13 June 2014; accepted 9 November 2014) A total of 2000 Hubbard Classic females and 180 males (male to female ratio 1:11) close to standard body weights were selected and managed separately in the same shed. The objective of this experiment was to study the effects of egg size (small, medium and large) at mid (45 weeks) production cycle and flock age (30, 45 and 60 weeks old) on hatching egg weight loss, fertility, hatchability traits, chick weight and chick yield in a commercial Hubbard Classic broiler breeder flock. The results showed that minimum egg weight loss (P 0.05) was recorded in large egg size group at different incubation periods and egg weight losses decreased with advancing the age of breeder hens. Maximum fertility and hatchability (P 0.05) was noticed in small egg size group, followed by medium and large egg size groups. However, maximum embryonic mortality (P 0.05) during incubation and higher percentage of infertile eggs was recorded in large size egg group, followed by medium and small egg size groups. Low fertility, hatchability was recorded (P 0.05) in older hen at the age of 60 weeks. The chick weight and chick length were amplified (P 0.05) with increasing the egg size. However, egg size was not influenced (P 0.05) on chick yield. The chick weight, chick yield and chick length were improved (P 0.05) with advancing age of broiler breeder. Keywords: egg weight loss; fertility; hatchability traits; chick weight; chick yield 1. Introduction Poultry production is the main source of household nutrition and income in the developing countries. Most of the poultry in the country is exotic breeds such as the Habbard chickens. Although broiler farming is running at commercial level, limited information exists on the effect of the hatching egg size and breeder age on hatching performance of Hubbard broiler chickens. This implies that their contribution to the household protein food security may not be fully realized without appropriate management and husbandry interventions as suggested by many workers (Abiola 1999; Donald et al. 2002; Rashid et al. 2005; King ori et al. 2007), who reported that performance in chickens in terms of hatchability and chick hatch-weight may be closely related to the weight of the eggs because the main effect of egg size lies in the mass of the residual yolk sac that the chick retains at hatching. King ori (2011) suggested that chick weight, fertility and hatchability are interrelated heritable traits that vary among breeds, variety or individuals in a breed; it therefore becomes very important to understand the effect of egg size on these traits in Habbard broiler chickens. Egg size has been widely studied in the context of the bird s life-history theory because it can be highly variable. In the production cycle of the breeder layers, the hen will begin to lay small eggs and in a matter of few weeks will go to medium size and then to the desired large size egg. Although egg size can be manipulated using fat levels, protein and enzymes, some other factors such as age and body weight of the hen, yolk weight and nutrient intake can influence egg size. Asuquo and Okon (1993) studied the effects of age in lay and egg size on fertility and hatchability of eggs. The workers noticed that egg size within the intermediate range of g would hatch better than small eggs. No biological reasons were suggested for such an observation. Some studies showed that the efficiency of reproduction of broiler breeders decreased with age, because it is related to the quality of hatching egg such as the internal egg composition or ratio, larger egg weight, poorer shell quality, increased early and late embryo mortality and other problems sole to large eggs from old broiler breeders (Elibol & Braket 2003; Tona et al. 2004; Joseph & Moran 2005). Broiler breeder age (Peebles et al. 2001) influenced subsequent embryogenesis and *Corresponding author. sohailhassan64@gmail.com 2014 Taylor & Francis

3 Journal of Applied Animal Research 55 hatchability of broilers. Fertility of an egg and embryonic mortality during the hatching process are known to be different for different strains. Deeming and Van Middelkoop (1999) reported that as the flock ages, there was more infertility and early embryonic mortality in eggs from Ross 308 compared with Cobb 500. It is well recognized that there is a strong relationship between breeder age and egg weight such that older hens produce larger eggs (Lourens et al. 2006). Chick weight increased with advancing age of broilers breeders as reported by Yildirim (2005) and Christensen et al. (2002). However, in past research, egg size and broiler breeder age have always been linked together (e.g., egg weight as a consequence of flock age; Wyatt et al. 1985). There is a lack of research evaluating the separate effects of flock age and egg size on chick production. Extensive research has not been done to determine the effect of egg size and age on fertility, hatchability traits and chick quality in commercial Hubbard Classic broiler breeder. The objective of this study was to examine the effects of egg size (small, medium and large) and flock age (30, 45 and 60 weeks old) on hatching egg weight loss, fertility, hatchability traits, chick weight and chick yield in a commercial Hubbard Classic broiler breeder flock. 2. Material and methods 2.1. Selection of birds and experimental site In this experiment, a commercial broiler breeder flock, Hubbard Classic strain (at 25 weeks of age) was selected for study, located in Islamabad territory. A total of 2000 Hubbard Classic females and 180 males (male to female ratio 1:11) close to standard body weights were selected and managed separately in the same shed. Male to female ratio was kept constant throughout production period. Any male observed sick or weak during the production period was immediately replaced with good quality healthy male from spare male kept at farm. Birds were vaccinated according to local vaccination programme and fed according to Management Guide book of Hubbard Classic strain. All other management practices during production periods (25 60 weeks) were adopted according to recommendations of Hubbard Classic strain Collection and storage of eggs All the eggs laid during 4 8 hour of light periods, from selected and separated broiler breeders, were collected from nests at interval of one hour, at 30, 45 and 60 week of breeder age. All substandard eggs like misshapen, cracked, dirty, blood-stained, toe-punched and elongated were rejected, and only oval shape good quality intact eggs were selected for hatching. The 930 eggs were selected from the hatching eggs at 30, 45 and 60 week of breeder age. To determine the effect of egg size on different parameters, eggs were equally distributed into three size categories (small, medium and large) at 45 weeks of age. A total of 300 hatchable eggs from each egg category were selected and shifted to Rose hatchery, located near Khannapul, Islamabad, Pakistan. These eggs were stored at 20 C and 75% relative humidity for three days Incubation and hatching conditions Three hundred (300) eggs of each size category (small, medium and large) were set into three trays (replicates). Average egg weight of each replicated tray having 100 hatchable eggs (experimental eggs) was calculated by an accurate electronic scale. Additional marked 65 eggs (non-experimental eggs) were also placed in each replicated tray for a parallel experiment. These three replicated trays of each egg size category were randomly placed to the top, middle and lower part of the setter of chick master machine (model ISI, having capacity of 95,040 eggs) to account for possible environmental difference caused by position in incubator. The setter was operated at a temperature of 37.5 C and a relative humidity of 60% during the first 18 day of incubation and eggs were turned after every hour. On 19th day of incubation, eggs of each replicated tray (experimental eggs) were transferred to separate hatch baskets and placed in a hatcher. The temperature was decreased to 37.0 C and the relative humidity was increased to 70%. After 21 days of incubation all hatched chicks were taken out of hatchers and shifted to chick s room of hatchery. The following hatchability parameters were studied during and after incubation period; 2.4. Measured egg weight loss during incubation All experimental eggs of each replicated tray of each egg size category were weighed just prior to setting into incubator to record average weight. At 7, 14 and 18 day of incubation, all experimental eggs of each replicated tray of each egg size category were removed from incubator and weighed by an electronic scale to calculate their average egg weight to measure the egg weight loss percentages Measured breakout analysis All hatched chicks from each egg size category were counted to assess hatchability percentage of set eggs. Chicks having physical abnormalities (weak, unhealed navels or red hocks, etc.) were considered unsalable and culled. The percentage of culled chicks was calculated on the basis of set eggs. After removing hatched chicks from hatch basket, all unhatched eggs were broken open to examine the infertile eggs and assess the approximate

4 56 J. Iqbal et al. day of embryonic death. The eggs that were pipped but failed to hatch were isolated and their percentages on the basis of set eggs were assessed. Embryonic mortality percentages were grouped into three categories, early (first week of incubation), mid (second week of incubation) and late (third week of incubation). The days of embryonic mortalities were assessed on the basis of embryo development. The eggs showing no embryonic development were considered as infertile eggs. Infertile egg percentages were calculated on the basis of set eggs. After assessing infertile eggs, hatchability percentage of fertile eggs were calculated. Hatchability percentages of set and fertile eggs were calculated on the basis of saleable chicks only Chick weight Chicks (male and female) hatched out of all replicates were weighed by an electronic balance to calculate the average chick weight (g) Measured chick yield Chick yield is the average chick weight divided by the average egg weight at the time of setting into incubator multiplied by 100. Grade-A chicks in all trays of each treatment (egg weight category) were vent sexed, counted and weighed by an accurate electronic scale to get average chick weight for the measurement of chick yield Chick length Thirty chicks (15 male and 15 female) hatched from each egg category (low, medium and heavy weight) were taken at random. Each selected chick was weighed individually by an accurate electronic scale to measure weight in gram then the length of the same chick was measured from the point of the beak to the middle toe (nail excluded) by using a calibrated foot. The weight (g) and length (cm) of individual chick was recorded. From these readings, average chick length (cm) and chick weight (g) for each egg weight were calculated Statistical analyses All data were determined by using the SPSS version 9.5 (SPSS, Cary, NC, USA) statistical analysis programme. A P value of <0.05 was considered for significant differences among groups, and the comparison of means was made by using Duncan s Multiple Range test (Steel & Torrie 1984). 3. Results and discussion 3.1. Effect of hatching egg size on egg weight Egg weight losses during incubation among different hatching egg size groups in broiler breeder flock at 45 week of age are given in Table 1. Significant differences (P 0.05) were found in egg weight loss of different egg size groups at mid stage of production period. However, non-significant difference (P 0.05) was found between small and medium egg size groups. Minimum egg weight loss (P 0.05) was recorded in large egg size group at different incubation periods. Egg weight loss determined during incubation in different egg size groups varied between 3.27% and 11.32%. The findings of the present study were similar to Abiola et al. (2008), who reported that although values obtained on egg weight loss for the three size categories: small ( g), medium ( g) and large ( g) in Anak broilers are comparable with one another, lowest egg weight loss of 11.24% was obtained for large eggs while highest egg weight loss of 11.57% was recorded for medium eggs. This may be due to the fact that small eggs have a higher surface-tovolume ratio and that there is an increase in the amount of water removed. Ulmer-Franco et al. (2010) reported that the percentage of egg weight loss decreased as egg size increased in Cobb 500 broiler breeder hen. Because of the increased surface-to-volume ratio in small eggs (inferred from egg size), it was not surprising to observe that the small eggs lost the highest percentage of moisture. Large eggs had a greater proportion of albumen (and thus greater moisture content) than small eggs. Abanikannda et al. (2011) reported that very low negative and non-significant correlation between egg Table 1. Effect of egg size on egg weight loss in a commercial Hubbard Classic broiler breeder flock at 45 weeks of age. Egg weight loss (%) at different incubation periods 1 Egg size Egg weight at time of incubation (g) 7 days 14 days 18 days Small a ± a ± a ± a ± 0.08 Medium b ± a ± a ± a ± 0.17 Large c ± b ± b ± b ± 0.08 SEM P value Note: Means with different alphabets in a column differ significantly (P 0.05). 1 Egg weight loss (%) = [(egg weight at setting egg weight at different days of incubation)/egg weight at setting] 100.

5 Journal of Applied Animal Research 57 size and egg weight loss up to the 18th day of incubation was indicated that weight loss was slower in bigger eggs compared to relatively smaller eggs in three strains of broilers (Anak-361, Marshall-359 and Ross-282). Average egg weight loss (7.75%) regardless the egg size class in the study is lower than the value of 12.94% reported by Soliman et al. (1994) for quail eggs. It is also lower than the values of 24.76% reported by Saylam (1999) and 20.90% reported by Saylam and Sarıca (1999) in quail eggs, and higher than the values of 1.25% reported by Khan et al. (2013) in Fayoumi eggs which consequently affect the chick weight at hatching. The differences in weight losses among different studies during incubation can be due to the difference in species. Egg weight loss that occurs during incubation of eggs is about utterly due to water diffusion through the shell (Tona et al. 2001). Most of the energy needed for the embryonic development is taken from the fat stores of the yolk, and for every gram of fat burned, an almost equal mass of metabolic water is generated. Incubation egg weight losses are a function of egg characteristics (shell structure, membrane structure and initial egg weight) and interacting incubation conditions (temperature, humidity and air velocity) under which the eggs were set (Gonzalez et al. 1999). Deeming (1995) determined that 10 12% weight loss is necessary during incubation in order to get a good incubation result in stored and non-stored eggs Effect of broiler breeder age on egg weight loss Egg weight losses during incubation among different age groups of broiler breeder flock are shown in Table 2. Egg weight loss percent was significantly (P 0.05) affected by breeder s age. Data showed that egg weight losses decreased with advancing the age of breeder hens. These results are in line with the findings of Reis et al. (1997), who found eggs from older breeders tended to lose more weight in grams but less in percentage when compared to eggs from younger breeders. This can be explained by the associated increase in egg weight with age, as larger eggs have less shell area per unit of interior egg weight than smaller eggs. Alsobayel et al. (2013) reported that cumulative values of egg weight losses in three breeds (Ross, Arbor acres and Cobb) were found as 1.19%, 1.11 and 1.08% at 30 35, and weeks of age, respectively. Results showed that Ross had significantly (P 0.05) the highest (1.3%) and the lowest (1.0%) egg weight loss percent at and weeks of age, respectively, while Arbor Acres had significantly (P 0.05) the lowest (1.80%) egg weight loss at weeks of age. Arbor acres showed the highest egg weight loss with advancing age whereas Ross had the highest and the lowest egg weight loss at early and middle age, respectively. This might be due to the fact that shell quality deterioration is higher with advancing age for Arbor Acres compared to other breeds. Zakaria et al. (2009) provided evidence to support that egg weight loss may be explained by liberation of water as a result of deterioration of the albumen with subsequent passage of unbound water through the eggshell as influenced by variation in albumen quality due to flock age, storage time and storage conditions (Tona et al. 2001). In the current study, the values of egg weight loss in Hubbard strain at different age were higher than the above study. In another study, Abanikannda et al. (2011) reported that the Anak breed had the highest egg weight loss while the Ross breed had the lowest with the Anak breed losing 17.62% and 6.92% more weight than Ross and Marshall, respectively, while Marshall lost 10% more than Ross. Data showed that Anak which had the smallest egg weight recorded the largest weight loss when compared to the other two breeds in the first 18 days of incubation. There is an inverse relationship between egg weight and weight loss between egg setting and candling at 18th day. The results on the mean percentage loss in the present study (11.25% at 18 days of incubation) are close to a loss of 11.40% as reported by Reis et al. (1997). Abudabos (2010) reported that egg weight loss from Ross strain-32 was 3.4%, 4.6% and 4.9% at 7, 14 and 19 days of incubation, respectively. Similarly, Ross strain-36 was 3.5%, 4.7% and 4.7% at 7, 14 and 19 days of incubation, respectively. The egg Table 2. Effect of age on egg weight loss in broiler breeder. Egg weight loss (%) at different incubation periods 1 Age (weeks) Egg weight at time of incubation (g) 7 days 14 days 18 days a ± a ± a ± a ± b ± a ± b ± ab ± b ± b ± b ± b ± 0.13 SEM P value Note: Means with different alphabets in a column differ significantly (P 0.05). 1 Egg weight loss (%) = [(egg weight at setting egg weight at different days of incubation)/egg weight at setting] 100.

6 58 J. Iqbal et al. weight loss from Cobb strain-26 was reported as 2.9%, 4.1% and 3.8% at 7, 14 and 19 days of incubation, respectively, and Cobb strain-44 was found as 2.7%, 4.2% and 4.0% at 7, 14 and 19 days of incubation, respectively. In the present study, the overall values of egg weight losses in Hubbard breed at different incubation periods were higher than the above study Effect of different hatching egg size on hatchability traits The influence of egg size on fertility and hatchability traits (hatchability, embryonic mortality, infertile eggs, pipped-not-hatched eggs and culled chicks) in broiler breeder flock at age of 45 week are shown in Table 3. At this stage of production, an average egg weight of small, medium and large eggs was 60.05, and g, respectively. Egg size had significant (P 0.05) effect on fertility and hatchability traits except pippednot-hatched eggs at mid (45 weeks) stage of production. Maximum fertility (P 0.05) was noticed in small egg size group (96.67%), followed by medium (93.33%) and large (90.33%) egg size groups. Similarly, maximum hatchability percentage (out of set eggs or fertile eggs) was achieved (P 0.05) in small egg size group (89.67% or 92.74%, respectively), followed by medium (83.63% or 89.61%, respectively) and large (78.33% or 86.72%, respectively) egg size groups. Maximum embryonic mortality (P 0.05) during incubation was recorded in large size egg group, followed by medium and small egg size groups. At mid stage of production period, maximum embryonic mortality (3.3%) was found in large size egg group during first week of incubation. Higher percentage of infertile eggs (P 0.05) was also found in large egg size group (9.67%), followed by medium (6.67%) and small (3.33%) size egg groups. No significant (P 0.05) effect of egg size was observed on pipped-not-hatched eggs. Maximum chicks (P 0.05) were culled in large size egg group (2.0%). Unquestionably, fertility and hatchability are two major parameters that highly influence on day-old chicks. It is therefore very important to understand the effect of egg size on fertility and hatchability traits. There is a scarcity of information on the effect of egg size on hatchability in Hubbard broiler chickens. The results of current study are agreed to other studies. Kirk et al. (1980) observed that fertility of the post-peak broiler breeders (60 weeks) declined by 11% and hatchability declined 9% in eggs weighing more than 70 g. This effect was explained in part by a relationship between breeder age and egg weight, as younger breeders produced eggs with superior hatchability at an average weight of 60 g. DeWitt and Schwalbach (2004) reported that large size eggs recorded to have higher hatchability in New Hampshire and Red Rhode Island chicken breeds at 30 weeks of age. In previous study, Wilson (1991) also reported that large-sized eggs had a higher hatchability value of 48.3% than medium- and small-sized eggs. Actually, hatchability of the incubated eggs increased as egg weight increased to large egg-size group of g. He suggested that egg size group of g were best suited for incubation. Similar results were obtained in the current study: best fertility and hatchability traits were obtained in small and medium egg size groups having g egg weight at the age of 45 weeks old. These results further supported by Ulmer- Franco et al. (2010), who analysed the effect of egg size Table 3. Effect of egg size on fertility and different hatchability parameters in a commercial Hubbard Classic broiler breeder flock at 45 weeks of age. Egg size Parameters Small Medium Large SEM P value Average egg weight (g) c ± b ± a ± Fertility (%) a ± b ± c ± Hatchability of set eggs (%) a ± b ± c ± Hatchability of fertile eggs (%) a ± b ± c ± Embryonic mortality (%) First week 2.0 b ± a ± a ± Second week 1.33 b ± ab ± a ± Third week 1.67 b ± ab ± a ± Infertile eggs (%) 3.33 c ± b ± a ± Pipped-not-hatched eggs (%) 1.33 ± ± ± Culled chicks b ± a ± a ± Note: Means with different alphabets in rows differ significantly (P 0.05). 1 Number of fertile eggs/number of eggs set Number of salable chicks hatched/number of total eggs set Number of salable chicks hatched/number of fertile eggs set Number of non-salable chicks culled at hatching/total number of eggs set 100.

7 Journal of Applied Animal Research 59 on the hatchability of a 43-week-old Cobb 500 flock and reported low hatchability in eggs that were larger than the average egg. This was a consequence of both high late embryo mortality and culled chicks. The lowest number of culled chicks was observed in the smaller and medium eggs at 43 weeks of age. Wilson (1991) also recommended that hatchability is a distinctive fitness trait with low heritability which may indicate that improvement by selection will take a long time to produce measurable results and hence optimization of hatching egg weight and hatchery management is therefore the most promising route for improvement. Literature showed inconsistent results due to certain factors like breed and age of flock. Nowaczewski et al. (2010) reported that the hatchability from fertilized and set eggs of Japanese quail in large size egg group was statistically significantly higher by, respectively, 6.8 and 9.3 percentage points in comparison with group small size eggs ( g). In the case of fertilized eggs as well as the proportion of necrosed embryos and unhatched chicks, no significant differences between groups were observed. Ng ambi et al. (2013) determined the effect of egg size (<49, 50 59, and >70 g) on hatchability in indigenous Venda chickens. They reported that egg weight was positively and strongly correlated with egg hatchability. Maximum hatchability was found in large size eggs (73.9%). Dudusola (2013) reported that higher fertility was observed in the heavy egg weight category of 36-weeks-old quail (92.59%) compared to that of the light weight category (89.90%). Madeddu et al. (2013) reported that egg size of Italian bantam breed (Mericanel della Brianza) significantly affected fertility and hatchability, and small egg size was associated with greater embryo mortality (66%) compared to large egg size (38 50%). Smaller size eggs were associated with greater embryo mortality, resulting in a lesser hatchability in the Cobb strain (Tona et al. 2001) as in case of present study; more embryonic mortality occurred in small egg size (51 g) at three weeks of age. In small eggs, there may be insufficient nutrients and pores, which could affect the embryo development and the hatching process; in fact, embryonic metabolism, such as lipid utilization and respiration, increases with embryonic growth (Mcloughlin & Gous 1999). In contrast of above studies, Abiola et al. (2008) reported that medium-sized eggs of Anak broiler (average 50 g) might be suitable for setting in other to obtain good hatchability, best result of weight gain and lower mortality. However, these workers recommended that where carcass traits are of special consideration, the large eggs would be preferred for setting. Similarly, Alabi et al. (2012) reported that medium egg size of Potchefstroom Koekoek chicks had the highest (P 0.05) hatchability (77%) than large (64%) and small (55%) egg size category. Further they reported that smaller eggs had higher (P 0.05) embryonic deaths (45%) than those of larger eggs (36%) and medium eggs (31%). Similarly, Rashid et al. (2013) also reported that percentage hatchability of medium-sized eggs was higher (P < 0.05) than those in large sized eggs in Fayoumi, Desi and crossbred (Rhode Island Red Fayoumi) chickens. These workers also suggested that if performance and carcass traits are of high importance then large eggs can be considered. The reason for the differences in hatchability among egg size groups in all above studies might be due to breed differences. The results of the above studies were also similar to the current study which revealed that better fertility and hatching traits were attained in medium egg size at the age of 45 weeks. Butcher and Nilipour (2012) provided practical industry standards for the various parameters monitored in an egg breakout programme. They advised that these standards could be used as a guide for comparison purposes. They compiled data from breakout analyses conducted during a five-year period from breeder flocks utilized at Group Melo, S.A. in Panama. These data were the average for the 40-week heavy breeder production cycle. The data showed that percentages of hatch, dead chicks, pipped-not-hatched eggs and infertile eggs should be 85, 0.25, 1.25 and 4.50, respectively. Contrary to above standards, present experiment (which was conducted in field condition) showed an average percentage of hatch, dead chicks, pipped-not-hatched eggs and infertile eggs at the age of 45 weeks old regardless the egg size were 89.7, 2.32, 1.0 and 6.55, respectively. When these results are compared with standards, parameters of hatchability and pipped-not-hatched eggs were satisfied, whereas values of chick mortality and infertile eggs were higher than above standards which could be because of difference in breeder age. Poor chick quality (culled chicks) has been associated with heavier than average egg weight for a particular flock age (Kumpula & Fasenko 2004; Lawrence et al. 2004). These findings are harmony with the results of present study in which maximum culled chicks were recorded in large size eggs than medium and small egg size groups at mid (2.00, 0.67 and 1.00, respectively) and late (3.66, 2.33 and 1.67, respectively) production stage periods Effect of broiler breeder age on fertility and hatchability traits The influence of broiler breeder age on fertility and hatchability traits (hatchability, embryonic mortality, infertile eggs, pipped-not-hatched eggs and culled chicks) are given in Table 4. Age of the hens had a significant (P 0.05) effect on fertility and hatchability traits except embryonic mortality. Low fertility, hatchability (out of set eggs and fertile eggs) was recorded (P 0.05) in older hen at the age of 60 weeks, however, non-significant

8 60 J. Iqbal et al. Table 4. Effect of broiler breeder age on fertility and hatchability traits (Means ± SE). Age (weeks) Parameters SEM P value Fertility (%) a ± a ± b ± Hatchability of set eggs (%) ab ± a ± b ± Hatchability of fertile eggs (%) ab ± a ± b ± Embryonic mortality (%) First week 3.30 ± ± ± Second week 2.33 ± ± ± Third week 3.11 ± ± ± Infertile eggs (%) 7.11 b ± b ± a ± Pipped-not-hatched eggs (%) 1.80 b ± b ± a ± Culled chicks b ± b ± a ± Note: Means with different alphabets in a rows differ significantly (P 0.05). 1 Number of fertile eggs/number of eggs set Number of salable chicks hatched/number of total eggs set Number of salable chicks hatched/number of fertile eggs set Number of non-salable chicks culled at hatching/total number of eggs set 100. difference (P 0.05) was observed between these parameters at the age of 30- and 45-weeks-old hens. Age of hen was not influenced (P 0.05) on embryonic mortality during incubation. Numerically, more embryonic death occurred in older age flock. More (P 0.05) infertile eggs and culled chicks were obtained in older hen at the age of 60 week compared with younger hen at the age of 30 and 45 weeks. However, older flock had better (P 0.05) pipped-not-hatched eggs than younger flock. The results of the present study were concurred with the findings of Tona et al. (2001), who reported that in a continuous study of a Cobb broiler breeder flock (from 27 to 60 weeks of age), the highest total hatchability and the lowest total embryo mortality at 40 weeks of age. The lowest hatchability and highest rates of embryo mortality were observed towards the end of the study at older flock ages (60 weeks old). The workers hypothesized that these results might have been due to a combined effect of high embryonic heat production and lower than optimal ventilation in the setter because of increased egg size. Vieira et al. (2005) found that eggs from old Ross-38 breeders (59 weeks old) were known to have an overall reduction in hatchability (73.5%) when compared to those from young breeder (88.3% and 82.3% for 27 and 40 weeks old, respectively), which is mostly related with increased embryo mortality and reduction in fertility. Similar results were obtained in the present study in which fertility and hatchability reduced and increased embryonic mortality (P 0.05) with advancing the age of Hubbard breeder. El-Safty (2012) reported that eggs laid by old breeders revealed higher infertility and total embryo mortality, resulting in lower hatching percentage, especially after 45 weeks of age. In concord with this result, Abudabos (2010) reported that hen s age affected hatchability and there was reduction of hatchability with advance age. This effect was more pronounced in the Cobb strain because of the bigger range of age (18 weeks difference) compared to four weeks for Ross strain. In previous work (Kirk et al. 1980), it was observed that fertility and hatchability decreased with age, fertility of 60 weeks broiler breeders declined by 11% and hatchability declined 9% as in case of the present study, 10.24% fertility and 7.41% hatchability declined at 60 weeks of broiler Hubbard Classic breeder. From a biological point of view, the fertility of eggs is affected by factors originating from the hen such as her ability to mate successfully, to store sperm, to ovulate an egg cell and to produce a suitable environment for the formation and development of the embryo (Brillard 2003). The hatchability of all settable eggs is a function of both the hen and her male mate. This is mostly due to the significant effect of both maternal and paternal components (parents) on fertility and early embryo survival. Literature showed that hatchability reduction of eggs from older broiler breeders is a result of many contributing factors, including larger egg size (Leeson & Summers 2000), increased early and late embryo mortality (Elibol & Braket 2003), poorer shell quality due to bigger surface area (Bennett 1992), albumen quality deterioration (Tona et al. 2004) and increased the yolk cholesterol content (Dikmen & Sahan 2007). Ransin (2005) provided the fertility and hatchability goals at certain ages of breeder flock. The standard showed that fertility and hatchability of 28-, 32-, 45- and 60-weeks-old breeder flock should be 91% and 83%, 97% and 88%, 97% and 88%, and 97% and 88%, respectively. In contrast to above standard, the current study showed that fertility and hatchability of 30-, 45- and

9 Journal of Applied Animal Research weeks-old breeder flock were found as and 85.84%, 93.44% and 89.70%, and 83.87% and 83.05%, respectively. The values of fertility were comparatively low than standard due to which hatchability percentages were also low except 45-weeks-old breeder flock. The percentage of chicks with low quality scores was reported to be higher in older (45 weeks) than in younger (35 weeks) flocks (Tona et al. 2004). Similar results are observed in the present study in which more culled chicks were recorded in older flock (2.56) as compared to younger (1.22) flocks Influence of egg size on chick quality The influence of egg size on chick weight, chick yield and chick length in commercial Hubbard Classic broiler breeder flock at mid (45 week) stage of production period is given in Table 5. Egg size had a significant (P 0.05) effect on chick weight and chick length. Data revealed that chick weight and chick length were amplified (P 0.05) with increasing the egg size. However, egg size was not influenced (P 0.05) on chick yield. There is a paucity of information on the effect of egg size on chick weight in Hubbard broiler chickens. Chick weight is the most widely used indicator for day-old chick quality assessment (Decuypere et al. 2002). It is known that a positive correlation exists between egg size and chick weight in broiler chickens (Abiola et al. 2008). Vieira et al. (2005) found that more chick weight (53.4 vs. 41 g) obtained from large egg size (72.7 ± 2.5 g) as compared to small egg size (57.7 ± 1.8 g) in 40-weeks-old Ross-38 breeders. Similar trend was observed in the current experiment: chicks gained more weight (47.50 vs g) from large egg size (70 g) than that of small egg size (60 g) at mid (45 weeks) stage of production in Hubbard breeder. Ulmer-Franco et al. (2010) reported that more chick weight (46.5 g) achieved from large egg size as compared to medium egg size (43 g) and small egg size (39.9 g) in commercial Cobb broiler breeder. In the current experiment, the values of chick weight in Hubbard broiler breeder were found higher than those obtained in above Cobb breeder study at any age or egg size groups. Abiola et al. (2008) reported that small chicks hatched from small eggs while large chicks hatched from large eggs in Anak broiler breeder. The positive correlation observed between egg size and chick hatching weight clearly identified the advantage of initial bigger egg size at the time of setting. In contrast, Sinclair et al. (1990) and Pinchasov (1991) indicated that there is a decline in the magnitude of correlation between egg weight and chick body weight with the advancement of age of the chick. The advantage of initially higher weight attributable to a larger egg diminishes rapidly after hatching while food intake is the main factor affecting final body weight (Wyatt et al. 1985). The results of final live weight also confirmed the significance of initial bigger egg size for incubation. The importance of egg weight as a factor in the performance of broiler chicks to market age has been reported (Wyatt et al. 1985). Recently, Rashid et al. (2013) reported that chick weight from large eggs (>45 g) were (P < 0.05) higher than those of small eggs (<41 g) in three rural breeds (Fayoumi, Desi and crossbred (Rhode Island Red Fayoumi). Williams (1994) suggested that heavier eggs contained more nutrients than small eggs, and hence, developing embryos from heavier eggs tended to have more nutrients for their growth requirements. Similar results were obtained in other poultry species: Ng ambi et al. (2013) reported that chick weight improved with increasing the egg size in indigenous Venda chickens. The data showed that the hatched chicks Table 5. Effect of egg size on chick weight, chick yield and chick length in a commercial Hubbard Classic broiler breeder flock at 45 week of age. Egg size Parameters Small Medium Large SEM P value Eggs set (no.) Egg weight (g) c ± b ± a ± Chick weight (g) Male c ± b ± a ± Female c ± b ± a ± Chick yield (%) 1 Male ± ± ± Female ± ± ± Chick length (cm) Male c ± b ± a ± Female c ± b ± a ± Note: Means with different alphabets in rows differ significantly (P 0.05). 1 Chick weight/set egg weight 100.

10 62 J. Iqbal et al. had 29, 31, 32 and 33 g weight for different egg size <49, 50 59, and > 70 g, respectively. Similarly in another study, the chick weight of Japanese quail (Coturnix coturnix japonica) was increased significantly as a result of the increasing egg size (Dudusola 2013). This increase in chick size due to increasing egg weight is attributable to the fact that egg weight, yolk weight and albumen weight improved as the age increased in chickens while egg shell quality deteriorated as reported by Hurnik et al. (1997). More recent research has shown that the chick length is now considered to be the best method of evaluating visual quality in meat type chickens (Mukhtar et al. 2013). Literature revealed that the large chick length was due to bigger egg size (Decuypere & Bruggeman 2007) as in case of present study. The other factors are effect on chick length are breeder age, hormone levels, blood metabolites levels (Decuypere & Bruggeman 2007), better glucose, thyroid and Corticosterone concentration (Christensen et al. 1996), higher rates of metabolism, gas exchange and good thermoregulatory ability (Weytjens et al. 1999) Effect of broiler breeder age on chick quality The influence of breeder age on chick weight, chick yield and chick length in commercial Hubbard Classic broiler breeder flock is shown in Table 6. Breeder age had a significant (P 0.05) effect on chick weight, chick yield and chick length. The results revealed that chick weight, chick yield and chick length were improved (P 0.05) with advancing age of broiler breeder. The results of the present experiment are agreed with other studies. In one study, chicks that hatched from older breeder flocks were usually larger and of higher quality because they were naturally more resistant to dehydration upon hatching as compared to smaller chicks from young breeder flocks (Sinclair et al. 1990). Tona et al. (2004) reported that chick weight increased with advancing age of breeders and the data showed that chick weight at 35 and 45 weeks of age in Cobb broiler breeder was found as and g, respectively. These values were high than the present study at the same age of breeder. This might be due to different strains used in both studies. Alsobayel et al. (2013) presented a cumulative data of three broiler breeders (Arbor Acres, Cobb and Ross) which indicated that hatched chicks attained weight as 41.4, 44.9 and 48.4 g at 30 35, and weeks of breeder age. These workers also reported that Cobb ranked first in chick weight (45.4 g) with advancing age of breeders followed by Ross (44.9 g) and Arbor Acres (44.5 g). However, in the present study, hatched chicks of Hubbard Classic breeder had more weight at any age of breeder than those of Arbor Acres, Cobb and Ross mentioned in the above study. In another study, maximum chick weight (51 vs g) was accomplished in 59-weeks-old Ross-38 breeders as compared to young breeder at 40 weeks of age (Vieira et al. 2005). A similar trend was observed in the present experiment: maximum chick weight (70.04 vs g) was attained in 60-weeks-old Hubbard breeder compared to 45-weeks-old breeder. Similarly, Ulmer-Franco et al. (2010) reported that more chick weight (48.9 vs g) achieved from 59-weeks-old Cobb breeder flock than that of 29-weeksold flock. These chick weight values were too low than the chick weight (67.67 g) gained in Hubbad breeder at 30 weeks of age in the present study. Contrary to above studies, Trehan and Bajwa (2001) did not observe any significant difference in chick weight of 42- and 50-weeks-old breeders. Similar results were reported in quail: Yildirim and Yetisir (1998) found that the parental age had no significant effect on the chick Table 6. Effect of broiler breeder age on broiler chick weight, chick yield and chick length (means ± SE). Age (weeks) Parameters SEM P value Eggs set (no.) Egg weight (g) b ± a ± a ± Chick weight (g) Male b ± ab ± a ± Female b ± ab ± a ± Chick yield (%) 1 Male b ± a ± a ± Female b ± a ± a ± Chick length (cm) Male c ± b ± a ± Female c ± b ± a ± Note: Means with different alphabets in rows differ significantly (P 0.05). 1 Chick weight/set egg weight 100.

11 Journal of Applied Animal Research 63 weight in Japanese quails at 22 and 65 weeks age. Similar findings were reported for quail chicks produced by 10- and 20-weeks-old hens (Seker et al. 2004). The probable reasons of these differences may be explained that the quails involved in parental age groups could fulfil or ensure the equal conditions for nutrition requirements of the embryo to be developed in the eggs as previously stated by Yildirim and Yetisir (1998). Decuypere and Bruggeman (2007) reported that total chick length was increased about 5% (from 19 to 20 cm) for breeders from 25 to 60 weeks of age. Whereas, in the current study, 11% chick length was increased in both male and female from 30 to 60 weeks of age in Hubbard broiler breeder. 4. Conclusion In conclusion, minimum egg weight loss was occurred in large egg size group at different incubation periods, and egg weight losses were decreased with advancing the age of breeder hens. For attaining better fertility and hatchability traits in broiler breeder flock, regardless the age, medium egg weight (60 69 g) should be selected for incubation. Fertility and hatchability of the flock were reduced with advancing the age of breeder hen. However, embryonic mortality, infertile eggs, pipped-nothatched eggs and culled chicks (not-saleable chicks) were increased with advancing the age of breeder hen. Maximum chick weight was attained from large egg size of breeder hen. Egg size ( g) had no influence on chick yield. However, chick yield was improved with extra large egg size (>70 g) of breeder hen. The chick weight, chick yield and sex yield were improved with advancing of age of breeder hen. References Abanikannda OTF, Leigh AO, Giwa AO Influence of egg weight, breed and age of hens on weight loss of hatching broiler eggs. Archiva Zootechnica. 14: Abudabos A The effect of broiler breeder strain and parent flock age on hatchability and fertile hatchability. Int J Poult Sci. 9: Abiola SS Effects of turning frequency of hen s egg in electric table-type incubator on weight losses, hatchability and mortality in Nigeria. Agric J. 30: Abiola SS, Meshioye OO, Oyerinde BO, Bamgbose MA Effect of egg size on hatchability of broiler chicks. Archivos de zootecnia. 57: Alabi OJ, Ng ambi JW, Norris D, Mabelebele M Effect of egg weight on hatchability and subsequent performance of Potchefstroom Koekoek chicks. Asian J Anim Vet Adv. 7: Alsobayel AA, Almarshade MA, Albadry MA Effect of breed, age and storage period on egg weight, egg weight loss and chick weight of commercial broiler breeders raised in Saudi Arabia. J Saudi Soc Agric Sci. 12: Asuquo BO, Okon B Effects of age in lay and egg size on fertility and hatchability of chicken eggs. Niger J Anim Prod. 20: Bennett CD The influence of shell thickness on hatchability in commercial broiler breeder flocks. J Appl Poult Res. 1: Brillard JP Practical aspects of fertility in poultry. World s Poult Sci J. 59: Butcher GD, Nilipour AH A systematic approach to solving hatchability and chick quality problems. This document is VM136, one of a series of the Veterinary Medicine-Large Animal Clinical Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date June Revised April Reviewed February Available from: Christensen VL, Donaldson WE, McMurtry JP Physiological differences in late embryos from turkey breeders at different ages. Poult Sci. 75: Christensen VL, Wineland MJ, Fasenko GM, Donaldson WE Egg storage alters weight of supply and demand organs of broiler chicken embryos. Poult Sci. 81: Deeming DC Factors affecting hatchability during commercial incubation of ostrich (Struthio camelus) eggs. Br Poult Sci. 36: Deeming DC, Van Middelkoop JH Effect of strain and flock age on fertility and early embryonic mortality of broiler breeder eggs. Br Poult Sci. 40: Decuypere E, Bruggeman V The endocrine interface of environmental and egg factors affecting chick quality. Poult Sci. 86: Decuypere E, Tona K, Bamelis F, Careghi C, Kemps B, De Ketelaere B, DeBaerdemaker J, Bruggeman V Broiler breeders and egg factors interacting with incubation conditions for optimal hatchability and chick quality. Archive für Geflügelkunde. 66: DeWitt F, Schwalbach LMJ The effect of egg weight on the hatchability and growth performance of New Hampshire and Red Rhode Island chicks. South Afr J Anim Sci. 34: Dikmen BY, Sahan U Correlations between breeder age, egg cholesterol content, blood cholesterol level and hatchability of broiler breeders. Br Poult Sci. 48: Donald D, Bell WD, Weaver JR Commercial meat and egg production. 5th ed. Norwell (MA): Kluwer Academic Publishers; p Dudusola IO The effect of parental age and egg weight on fertility, hatchability and day-old chick weight of Japanese quail (Coturnix coturnix japonica). Standard Res J Agric Sci. 1: Elibol O, Braket J Effect of frequency of turning from three to eleven days of incubation on hatchability of broiler hatching eggs. Poult Sci. 82: El-Safty SA Influence of genotype and age of egg-type breeders on some hatching traits. Egypt Poult Sci. 32: Gonzalez A, Satterlee DG, Moharer F, Cadd GG Factors affecting ostrich egg hatchability. Poult Sci. 78: Hurnik JF, Summer JD, Reinhart BS, Sweirczewks EM Effect of age on the performance of laying hens during the first year of production. Poult Sci. 56: Joseph NS, Moran Jr ET Effect of flock age and postemergent holding in the hatcher on broiler live performance and further-processing yield. J Appl Poult Res. 14: Khan MJA, Khan SH, Bukhsh A, Abbass MI, Javed M Effect of different storage period on egg weight, internal egg quality and hatchability characteristics of Fayumi eggs. Ital J Anim Sci. 12e51: