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Relationship Between Chick Conformation and Quality Measures with Early Growth Traits in Males of Eight Selected Pure or Commercial Broiler Breeder Strains

N. J. Wolanski^*, R. A. Renema^*, F. E. Robinson^*,1, V. L. Carney and B. I. Fancher

^* Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2P5; Alberta Agriculture, Food and Rural Development, Livestock Development Division, Edmonton, Alberta, Canada T6H 5T6; and Aviagen Inc., Huntsville, AL 35805

¹ Corresponding author: frank.robinson{at}ualberta.ca

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Current commercial broiler products are derived from the crosses of various strains at the primary breeder level. This study investigated chick development, yolk utilization, and early growth rate of males from 8 broiler breeder strains. These strains were a combination of both specialized and commercial-line products. At hatch, 110 male chicks per strain were weighed and wing-banded, and chick quality was assessed. Traits included navel condition, hock color, chick length, shank length, and abdomen score by abdominal palpation (to evaluate residual yolk content on live chicks). At hatch, 50 chicks per strain were dissected to assess breast muscling and residual yolk weight. At 2 wk of age, 50 chicks per strain were dissected to characterize changes in weight, conformation, fleshing, and residual yolk content. Chick weight at hatch varied from 40.8 g in a heavily growth-selected line to a low of 36.9 g in a commercial strain. The mass of residual yolk at hatch ranged from 0.8 to 10.6 g across all chicks dissected at hatch. A heavily breast-selected pure-line strain had 5.8 g of residual yolk in contrast to the commercial strain that had only 3.0 g. Although there were no significant strain differences in abdomen score, this score correlated with dissected residual yolk weight (r = 0.50). Shank length and chick body length at hatch correlated more strongly with BW on d 14 than did hatch weight. This information stresses the importance of evaluating several characteristics at hatch to better quantify early chick quality.

Key Words: chick quality • residual yolk • genetic strain • growth rate

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Over the last 40 yr, the number of days to market for broilers has decreased by approximately 1 d/yr (Nir and Levanon, 1993). Because the first week following hatch currently represents nearly 20% of a broiler’s life, growth in the first few days, or even hours, is becoming an essential component of the efficient achievement of market BW. During the first 2 wk of incubation, carbohydrate and protein metabolism predominate (Peebles et al., 1999), whereas during the last week, the chick utilizes lipids from the yolk sac as an energy substrate for growth (Noble and Cocchi, 1990). The yolk has been estimated to supply 90% of the total caloric needs of a chicken embryo (Freeman and Vince, 1974). Chicks do not have the ability to properly utilize dietary lipids at hatch (Escribano et al., 1988). During the first 2 wk, as this ability develops (Carew et al., 1972), limited bile salts are a primary cause of inadequate micellar solubilization of dietary lipids (Gomez and Poulin, 1974).

A large proportion of lipids (2 g) are transferred to the chick embryo from 19 to 21 d of incubation (Ding and Lilburn, 1996). When broilers are provided with a carbohydrate diet, they must switch from utilizing yolk solids to digesting and absorbing carbohydrates. This transition from yolk absorption to one of utilizing carbohydrates is often difficult and may explain why mortality is often high in the first week (Applegate, 2002).

Research reported by Tona et al. (2003a) has investigated chick quality as evaluated by several qualitative characteristics for newly hatched chicks. Chicks scoring 100 had a significantly better relative growth rate than chicks that received any lower score. Two of their 8 criteria related to evaluation of the residual yolk of a chick, illustrating the importance of assessing yolk reserve at hatch. Residual yolk mass is extremely variable at hatch, and various estimates by researchers have ranged from 8 g or 20 to 25% (Noy et al., 1996), 7.9 g or 16.8% (Chamblee et al., 1992), to 6.6 g or 15.5% of a chick’s BW (Murakami et al., 1992).

The residual yolk contained in the chick declines from hatch and is negligible by 11 d of age (Nitsan et al., 1995). However, the initial residual yolk mass can be affected by initial egg yolk size, incubation conditions, and time of hatch (Tona et al., 2003b). Also, there are genotypic effects on incubation length (Crittenden and Bohren, 1961; Siegel et al., 1968; Suarez et al., 1997). Strains differing in selection criteria also have slightly differing metabolic strategies during incubation and hatch (O’Dea et al., 2004).

Residual yolk sac weight and composition is affected by many factors, such as age of dam, egg storage, incubation conditions, and egg size. However, information on yolk sac content over a wide range of genotypes is lacking. The objective of this study was to survey a broad range of genotypes from 1 breeding company (both pure and commercial lines) for relative size of the yolk sac, breast weight, carcass weight, and chick body length in male broiler breeder chicks. The potential relationship between residual yolk and frame size on BW after 2 d, chick body length, and breast muscle fleshing was also assessed.

	MATERIALS AND METHODS

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In this study, eggs from 8 broiler breeder genotypes (Table 1) were obtained from a commercial breeder (Aviagen North America, Huntsville, AL) and then shipped to the University of Alberta. Eggs were obtained from hens with as narrow a range in age as possible to reduce the potential effect of hen age on residual yolk sac. Eggs were placed in a 5,000-egg-capacity incubator (Jamesway Incubator Company Inc., Cambridge, Ontario, Canada) 9 d after being laid. Chicks were vent sexed at hatch, and only males were used in this study. Each chick was neck-tagged (Heartland Animal Health Inc., Fair Play, MO) and weighed. Subsequently, chicks were subjected to a shank length measurement of the tibia tarsus from the top of the hock joint to the bottom of the footpad. Also, a bird-length measurement from the tip of the beak to the end of the middle toe with the chick’s dorsal surface extended over a ruler was measured. Navel condition of each chick was evaluated, and the incidence of navel imperfections, such as a navel button (slight opening of the navel) or navel wick (residual yolk membrane attached to navel), was recorded. The abdomen of each chick was manually palpated by a single trained individual to estimate the yolk reserves. A 3-point scale was used, in which a score of 1 represented a chick with very little residual yolk, a score of 2 denoted a chick with an average amount of residual yolk, and a score of 3 equated to a chick that had a grossly distended abdomen.

An additional 60 males per strain were randomly selected at hatch to be grown out for a 2-wk period. On the day of hatch, chick BW, bird length, shank length, abdomen score, and navel condition were recorded. Approximately 10 h after hatching, the birds were randomly placed in 1 of 2 adjacent pens (2.32 x 5.49 m; 240 birds/pen), with each strain equally represented in the pens. The chicks were reared on a broiler starter diet (Table 2) with ad libitum access to feed and water, with a photoperiod of 23L:1D. At 2 wk of age, 50 birds per strain were randomly selected, and the BW, shank length, and chick body length were measured. Also, the length of the keel bone was measured from the hypocleido-clavical joint to the caudal end of the sternum with digital calipers while the bird was held horizontally (ventral side up). These birds were then killed and dissected to determine breast muscle weight and characterize the presence or absence of residual yolk. The residual yolk sacs were weighed both fresh and after being dried for 4 d at 60°C.

	RESULTS AND DISCUSSION

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Chicks at 0 d of Age
The mean hatch BW, carcass weight, residual yolk sac weight, and breast muscle weight for each of the 8 strains are shown in Table 3. Chicks from the pure-line strains generally weighed more than the commercial chicks did. Strains S1 (40.8 g), S2 (40.6 g), and S4 (41.1 g) had the greatest hatch weight, whereas S6 (37.2 g) and S7 (37.2 g) had the lowest hatching weight. The differences observed in hatch weight may have been influenced by initial egg size. Although initial egg weight was not recorded in this trial, females originating from the same hatch produced from 105 (S1) to 163 (S6) eggs in total by 56 wk of age (Rustad et al., 2005), with the heavily growth-selected S1 hens producing a larger hatching egg. In a subsequent trial, eggs from commercial lines that were 46 to 57 wk of age weighed 64.4 g compared with 65.7 g in the pure lines (N. Wolanski, unpublished data). Resulting chick weights were 2.5 g higher, on average, in the pure lines compared with the commercial lines. In the current study, the contrast between chick weights of the pure and commercial lines common to both studies indicates a 2.4 g difference in chick weight within the pure lines (Table 3). Although Wolanski (unpublished data) used older hens, the resulting chick weight differences were comparable to those in our study, demonstrating that the range in initial egg weight is likely also relevant for the current study. Differences in rate of lay among the strains tested likely contributed to differences reported in initial egg weight (N. Wolanski, unpublished data), with the pure lines producing fewer eggs (Rustad et al., 2005). Birds that lay fewer eggs tend to have a higher incidence of first-of-sequence eggs, which will generally have a larger yolk (Robinson et al., 1991). Bray and Iton (1962), Silversides and Scott (2001), and Tona et al. (2004a) have shown that egg weight can have a significant influence on hatch weight, although the subsequent relationship between egg weight and BW at 42 d of age is poor.

In terms of yolk-free carcass weight, the pure-line S2 chicks had the greatest amount of body reserves (35.6 g; Table 3). This yolk-free mass represented 87.7% of the chicks’ initial hatch weight. In contrast, S4 (heavily breast-selected strain with less emphasis on growth) had one of the highest hatch weights, yet it had one of the numerically lowest yolk-free carcass weights (33.2 g). The percentage of yolk-free carcass in this strain was only 80.8%. The fact that S4 was a heavily breast-selected line may partially explain why it had the least amount of carcass reserves at hatch. Current studies suggest that high breast-yield strains have a higher metabolic rate and, consequently, may need to be managed differently throughout incubation to effectively dissipate excess heat and CO2 (O’Dea et al., 2004). If incubator and hatcher conditions are suboptimal for these newly developed strains, the resulting chicks may be of poorer quality (i.e., larger yolk sacs and less carcass reserves). The eggs of the current study were incubated according to current industry practices. The incubator was less than half full, reducing the effect of impeded heat exchange with the air. Because the hatch was pulled at the same time for all strains, differences in incubation length requirements among strains could conceivably have affected traits, such as chick dehydration, at this time. However, hematocrit analysis of sample chicks from each strain demonstrated no apparent effect on this trait (N. Wolanski, unpublished data). The S5 chicks had a yolk-free carcass weight of 34.4 g, whereas 2 similar commercial products (S6 and S7), which have slightly more emphasis on breast meat yield, had significantly less carcass reserves at hatch (32.6 and 32.9 g, respectively; Table 3).

Tona et al. (2004b) suggested that hatching BW alone may not accurately describe the quality of a chick, so they designed a qualitative scoring system that evaluated several parameters at hatch to better quantify chick quality. Although hatch weight can be used as a measure of chick quality, it is often misleading, because hatch weight also includes yolk residue that is internalized within the abdomen of a chick. The mass of the residual yolk in newly hatched chicks is extremely variable, and it ranged from 0.8 to 10.6 g in individual chicks (mean = 4.3 g; 11% of chick weight; Table 3) in this study. Tona et al. (2003a) examined the height and consistency of the abdomen of newly hatched chicks. Yolk residue usually constitutes about 10 to 12% of a chick’s BW at hatch (Murakami et al., 1988, 1992; Nitsan et al., 1991). Whereas many of the recent studies indicate higher residual yolk values than those of the current study, Bierer and Eleazer (1965) found that the average residual yolk weight of newly hatched chicks was 5.4 g, although initial chick weight was not reported.

The manual palpation scores (range of 1 to 3) did not differ among the strains. However, with a larger scale (1 to 5), it may be possible to discern strain differences. At the time of hatch, S1 and S4 had 5.7 and 5.8 g of residual yolk, respectively (Table 3). In contrast, S6 and S7 (commercial strains) only possessed 3.1 and 3.0 g of residual yolk, respectively. The dried yolk-sac weights for S1 and S4 were 3.0 and 3.1 g of unutilized yolk solids, respectively, which was similar to the wet weight for the commercial lines, S6 and S7. The dry weights of S6 and S7 were 1.7 and 1.5 g, respectively. From this evidence, it is apparent that the commercial strains had less yolk reserves to utilize. The commercial strains may have been more efficient at utilizing yolk solids, or the initial yolk size of these eggs was smaller than the other strains examined. Broiler breeder strains S5, S6, and S7 were the commercial lines, with yolk reserves at hatch being 3.8, 3.1, and 3.0 g, respectively (Table 3). Incubation conditions appeared well suited to these commercially important strains, as indicated by their low residual yolk levels at hatch.

The larger, pure-line chicks of strains S1 to S4 carried more breast muscle at hatch than the commercial and experimental strains (S5 to S8; Table 3). Even when compared relative to BW, breast muscle of the S2 chicks accounted for 1.4% of chick BW compared with 1.1% in S6 and S8. Research by Lilburn and Nestor (1991) demonstrated that, at hatch, the pectoralis major weight for rapid growth-selected turkeys was significantly greater as compared with a similar unselected strain. More recently, Liu et al. (2004) reported differences in breast muscle weights at 16 d of embryonic development, and the magnitude of the line differences generally increased through 16-wk posthatch. Differences in breast muscling at hatch were believed to be the result of increased proliferation and differentiation of myoblasts during embryogenesis (Liu et al., 2004).

Body length at d 0 ranged from 185 mm in the pure-line S3 chicks to 194 mm in the commercial S5 chicks at the time of hatch (Table 4). Strain 4 chicks had a compact frame size with a relatively short body length of 188 mm and shank length of 27.2 mm. This could be the direct result of increased selection for breast muscle yield in this line. A study by Msoffe et al. (2001) reported a positive correlation between both body length (r = 0.96) and shank length (r = 0.96) with adult BW in the scavenging local chickens of Tanzania. Therefore, at hatch, measuring body length and shank length may be a useful tool to identify early growth potential based on initial frame size, rather than using hatch BW as a sole predictor of growth potential. Embryo development can be expressed in terms of embryo length (Hill, 2001).

The external morphometrics of these 8 strains continually showed that S1 had the longest shank and body length, whereas S4 had the shortest. The same relationship was evident for keel length. Strain 1 chicks had a keel length of 68 mm, and S4 chicks had a keel length of 58 mm. Although the percentage of breast muscle deposition between these 2 strains was not significantly different, S4 appears to have accreted breast muscle in a different manner (wider chest girth) than S1, which deposits breast muscle along the length of its keel.

At the time of hatch, S1 chicks had almost a 4 g advantage in BW compared with S6 and S7 chicks (Table 3). By 14 d of age, S1 chicks had an average BW of 427 g, which was almost 100 g greater than some other strains (S3, S4, S6, S7; Table 6). In terms of absolute weight gains within the first 2 wk, S1 gained 386 g, whereas S4 had only gained 264 g. The fact that S4 grew more slowly may be attributed to the fact that it has a different genetic potential for growth. Some of this difference may be attributed to the fact that S4 was shown to have a poorer yolk utilization (Table 3). Murakami et al. (1992) compared deutectomized and intact chicks and found that there was a 2-d delay in growth of the deutectomized chicks; the authors concluded that yolk lipids in the newly hatched chick have a crucial role in the initiation of growth. It has been shown that chickens selected for rapid growth possess a higher metabolic rate than unselected birds (Jorgensen et al., 1990; Buys et al., 1998). These same birds may possess a higher metabolic rate inside the egg as long as factors such as energy substrate, oxygen, or carbon dioxide were not limiting or in excess. Tona et al. (2004b) found that chicks with higher metabolic rates scored higher on the chick quality scale and had better 7-d growth performance.

At 14 d of age, S1 had 52 g of breast muscle, which constituted 12.0% of the bird’s total BW (Table 6). In contrast, S3 had only 31 g of breast muscle (9.4% breast muscle). The heavily breast-selected strains, S4 and S8, did not have the largest breast weight. However, their relative percentages of breast muscle (12.0 and 12.6%) were similar to S1. Among the 3 commercial strains (S5, S6, and S7), as the selection pressure increased for white meat yield, there was a trend toward greater breast muscle percentage, with the strains having 11.1, 11.3, and 11.7% breast muscle, respectively.

By 14 d of age, all of the strains had very little residual yolk remaining. However, on average, S1 chicks still had 0.4 g of residual yolk, which was significantly greater than all the strains except S4 and S8. This is similar to the trend at hatch, in which S1 and S4 had the greatest yolk reserves, with S8 having slightly less yolk reserves.

Correlations
The manual palpation scores were correlated with actual residual yolk sac weights (r = 0.50). With a larger scale and more fine-tuning, this abdomen score may allow for an accurate estimate of chick yolk reserves at hatch. Body weight was a key factor in significant correlations found at hatch (Table 7). There was a significant correlation between breast muscle weight and hatch weight across all strains examined (r = 0.46). The use of length measurements, such as chick body length and shank length at hatch, correlated with a chick’s wet carcass reserves (r = 0.60 and r = 0.56). Therefore, these measurements at hatch may elucidate the amount of body reserves that have been synthesized during the incubation period.

	ACKNOWLEDGMENTS

 
We are grateful to Aviagen North America for their in-kind donation of the breeder eggs. The assistance of Lilydale Foods is also appreciated. We also acknowledge the excellent assistance from staff and students of the Alberta Poultry Research Centre.

Received for publication December 21, 2005. Accepted for publication April 1, 2006.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Applegate, T. J. 2002. Reproductive maturity of turkey hens: Egg composition, embryonic growth and hatchling transition. Avian Poult. Biol. Rev. 13:31–41.

Bierer, B. W., and T. H. Eleazer. 1965. Effects of feed and water deprivation on yolk utilization in chicks. Poult. Sci. 44:1608–1609.

Bray, D. F., and E. L. Iton. 1962. The effect of egg weight on strain differences in embryonic and post-embryonic growth in the domestic fowl. Br. Poult. Sci. 15:175–187.

Buys, N., E. Dewil, E. Gonzales, and E. Decuypere. 1998. Different CO₂ levels during incubation interact with hatching time and ascites susceptibility in two broiler lines selected for different growth rate. Avian Pathol. 27:605–612.

Carew, L. B. Jr., M. A. Machemer Jr., R. W. Sharp, and D. C. Foss. 1972. Fat absorption by the very young chick. Poult. Sci. 51:738–742.[ISI][Medline]

Chamblee, T. N., J. D. Brake, C. D. Schultz, and J. P. Thaxton. 1992. Yolk sac absorption and the initiation of growth in broilers. Poult. Sci. 71:1811–1816.[ISI][Medline]

Crittenden, L. B., and B. B. Bohren. 1961. The genetic and environmental effect of hatching time, egg weight, and holding time on hatchability. Poult. Sci. 40:1736–1750.

Ding, S. T., and M. S. Lilburn. 1996. Characterization of changes in yolk sac and liver lipids during embryonic and early post-hatch development of turkey poults. Poult. Sci. 75:478–483.[ISI][Medline]

Escribano, F., B. E. Rahn, and J. L. Sell. 1988. Development of lipase activity in yolk membrane and pancreas of young turkeys. Poult. Sci. 67:1089–1097.[ISI][Medline]

Freeman, B. M., and M. A. Vince. 1974. Page 163 in Development of the Avian Embryo. Chapman and Hall, London, UK.

Gomez, M. X., and D. Poulin. 1974. Influence of cholic acid on the utilization of fats in the growing chicken. Poult. Sci. 55:2189–2195.

Hill, D. 2001. Chick length uniformity profiles as a field measurement of chick quality? Avian Poult. Biol. Rev. 12:188. (Abstr.)

Jorgensen, H., P. Sorensen, and B. O. Eggum. 1990. Protein and energy metabolism in broiler chickens selected for either body weight gain or feed efficiency. Br. Poult. Sci. 31:517–524.[ISI][Medline]

Lilburn, M. S., and K. E. Nestor. 1991. Body weight and carcass development in different lines of turkeys. Poult. Sci. 70:2223–2231.[ISI][Medline]

Liu, X., K. E. Nestor, and S. G. Velleman. 2004. The influence of selection for increased body weight and sex on pectoralis major muscle weight during the embryonic and posthatch periods. Poult. Sci. 83:1089–1092.[Abstract/Free Full Text]

Merritt, E. S., and R. S. Gowe. 1965. Post embryonic growth in relation to egg weight. Poult. Sci. 44:477–480.[ISI][Medline]

Moran, E. T. Jr. 1990. Effects of egg weight, glucose administration at hatch, and delayed access to feed and water on the poult at 2 weeks of age. Poult. Sci. 69:1718–1723.[ISI][Medline]

Msoffe, P. L. M., U. M. Minga, J. E. Olsen, M. G. S. Yongolo, H. R. Juul-Madsen, P. S. Gwakisa, and M. M. A. Mtambo. 2001. Phenotypes including immunocompetence in scavenging local chicken ecotypes in Tanzania. Trop. Anim. Health Prod. 33:341–354.[ISI][Medline]

Murakami, H., Y. Akiba, and M. Horiguchi. 1988. Energy and protein utilization in newly-hatched broiler chicks: Studies on the early nutrition of poultry. Jpn. J. Zootech. Sci. 59:890–895.

Murakami, H., Y. Akiba, and M. Horiguchi. 1992. Growth and utilization of nutrients in newly-hatched chicks with or without removal of residual yolk. Growth Dev. Aging 56:75–84.[ISI][Medline]

Nir, I., and M. Levanon. 1993. Effect of post hatch holding time on performance and on residual yolk and liver composition. Poult. Sci. 72:1994–1997.

Nitsan, Z., E. A. Dunnington, and P. B. Siegel. 1991. Organ growth and digestive enzyme levels to 15 days of age in lines of chickens differing in body weight. Poult. Sci. 70:2040–2048.[ISI][Medline]

Nitsan, Z., I. Turro-Vincent, G. Lui, E. A. Dunnington, and P. B. Siegel. 1995. Intubation of weight-selected chicks with soybean oil or residual yolk: Effect on early growth and development. Poult. Sci. 74:925–936.[ISI][Medline]

Noble, R. C., and M. Cocchi. 1990. Lipid metabolism and the neonatal chicken. Prod. Lipid Res. 29:107–140.

Noy, Y., Z. Uni, and D. Sklan. 1996. Routes of yolk utilization in the newly-hatched chick. Br. Poult. Sci. 37:987–996.[ISI][Medline]

O’Dea, E. E., G. M. Fasenko, J. J. R. Feddes, F. E. Robinson, J. C. Segura, C. A. Ouellette, and J. H. van Middelkoop. 2004. Investigating the eggshell conductance and embryonic metabolism of modern and unselected domestic avian genetic strains at two flock ages. Poult. Sci. 83:2059–2070.[Abstract/Free Full Text]

Pinchasov, Y. 1991. Relationship between the weight of hatching eggs and subsequent early performance of broiler chicks. Br. Poult. Sci. 32:109–115.[ISI][Medline]

Peebles, D. E., L. Li, S. Miller, T. Pansky, S. Whitmarsh, M. A. Latour, and P. D. Gerard. 1999. Embryo and yolk compositional relationships in broiler hatching eggs during incubation. Poult. Sci. 78:1435–1442.[Abstract/Free Full Text]

Robinson, F. E., R. T. Hardin, N. A. Robinson, and B. J. Williams. 1991. The influence of egg sequence position on fertility, embryo viability, and embryo weight in broiler breeders. Poult. Sci. 70:760–765.[ISI][Medline]

Rustad, M. E., F. E. Robinson, R. A. Renema, M. J. Zuidhof, and V. L. Carney. 2005. Effects of over feeding on sexual maturation and egg production in 8 strains of broiler breeder hens. Poult. Sci. 84(Suppl. 1):48. (Abstr.)[Abstract/Free Full Text]

SAS Institute 2002. SAS/STAT User’s Guide. Version 9.1. SAS Inst. Inc., Cary, NC.

Siegel, P. B., J. W. Coleman, H. B. Graves, and R. E. Phillips. 1968. Incubation period of chicken selected bi-directionally for juvenile body weight. Poult. Sci. 47:105–107.

Silversides, F. G., and T. A. Scott. 2001. Effect of storage and layer age on quality of eggs from two lines of hens. Poult. Sci. 80:1240–1245.[Abstract/Free Full Text]

Suarez, M. E., H. R. Wilson, F. B. Mather, C. J. Wilcox, and B. N. Mcpherson. 1997. Effect of strain and age of the broiler breeder female on incubation time and chick weight. Poult. Sci. 76:1029–1036.[Abstract/Free Full Text]

Tona, K., F. Bamelis, B. De Ketelaere, V. Bruggeman, V. M. B. Moraes, J. Buyse, O. Onagbesan, and E. Decuypere. 2003a. Effects of egg storage time on spread of hatch, chick quality, and chick juvenile growth. Poult. Sci. 82:736–741.[Abstract/Free Full Text]

Tona, K., R. D. Malheiros, F. R. Bamelis, C. Careghi, V. M. B. Moraes, O. Onagbesan, E. Decuypere, and V. Bruggeman. 2003b. Effects of storage time on incubating egg gas pressure, thyroid hormones, and corticosterone levels in embryos and on their hatching parameters. Poult. Sci. 82:840–845.[Abstract/Free Full Text]

Tona, K., O. Onagbesan, B. De Ketelaere, E. Decuypere, and V. Bruggeman. 2004a. Effects of age of broiler breeders and egg storage on egg quality, hatchability, chick quality, chick weight, and chick posthatch growth to forty-two days. J. Appl. Poult. Res. 13:10–18.[Abstract/Free Full Text]

Tona, K., O. M. Onagbesan, Y. Jego, B. Kamers, E. Decuypere, and V. Bruggeman. 2004b. Comparison of embryo physiological parameters during incubation, chick quality, and growth performance of three lines of broiler breeders differing in genetic composition and growth rate. Poult. Sci. 83:507–513.[Abstract/Free Full Text]

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