Effects of Chick Quality and Pre-Starter Feed on Fattening Performance and Carcass Characteristics of Broilers

The present study was conducted to investigate the effects of chicks quality and pre-starter feeding during the first five days of the feeding period on performance and carcass characteristics. After hatching, experimental chicks were divided into sex by employing 2 by 2 factorial design chick quality (low and high) and two feeding regimes as the main effects in each sex. Thus, four treatment groups (low quality on starter feed, low quality on pre-starter+starter feed, high quality on starter feed, high quality on pre- starter+starter feed) were arranged in the study. Total of 800 chicks was used in four treatment groups including five replicates each, using 40 chicks (20 males and 20 females) per replicates. At the beginning of the experiment, initial live weight was seen to be affected by chick quality, as the mean body weights of the high-quality chick groups were 1.3 g heavier than those of the low-quality chick groups (P < 0.001). However, at the end of the experiment, the use of pre-starter feeding and chick quality did not affect body weight gain, feed consumption, feed conversion rate or mortality rate significantly (P > 0.05). With regard to the fatness of the carcass, a higher amount and proportion of abdominal fat were found in low-quality female chicks (P < 0.05).


INTRODUCTION
A s the human population continues to increase, it has become necessary to increase food production and quality to meet the demand for quality food and to ensure the availability of a balanced diet for human nutrition. It is well known that poultry meat is one of the main sources of good quality protein. In fact, the economy, quantity and quality of poultry meat production are significantly affected by chick quality (CQ), which is known to be affected by many factors. Besides genotype and age of breeder flock, CQ is affected by three stages including pre-hatching (feeding breeder, egg quality, collection and storage conditions etc.), hatching (incubation temperature, humidity, ventilation and turning of eggs) and post-hatching (the first 7 days feeding) (Durmuş and Kutlu, 2019). It is well known that these factors cover a long process from the feeding of breeder flock to slaughter of broilers. Depending on the effects of all these factors, chicks are produced of different quality and meat yield from broiler production could vary according to the quality of chicks (Durmuş et al., 2021). Therefore, CQ is the combination of many parameters and it is essential for the enhancement of production and slaughter performance. Quality of chicks are defined as those that have developed optimally during the incubation period and have a high growth rate, high breast meat ratio and high survival rate after hatching (Kamanlı and Durmuş, 2014). It is difficult to identify chicks that would have a better performance after incubation, as there have been no quality classification systems established in most of the broilers producing countries. Activity, general appearance, the color of feathers, condition of eyes, structure of legs, open or closed navel, etc. at hatching could be the main criteria taken into account in determining CQ (Tona et al., 2003). According to the studies conducted on chicks' quality, one of the most important features of healthy chicks after hatching is the ability of standing upright on the feets and clear and bright eyes. Moreover, it is well known that egg yolk provides necessary nutrients for the development of the embryo and the color pigments of the feathers at hatching. Absorption at a high rate of the yolk sac by the chicks at the end of the incubation could sign dark yellow feathers at hatching (Meijerhof, 2005). For this reason, the feathers' color of the chick is desired to O n l i n e F i r s t A r t i c l e be yellow as dark as possible. Also, it is speculated that the weight of the heart, liver and spleen and the length of the digestive system increase in parallel with the length of the chick and the intestinal system develops better (Reijrink and Molenaar, 2006). Since qualitative characteristics of chicks at hatching cannot be measured or converted into quantitative scores, to make subjective interpretation is really difficult to achieve repeatable success. In the present literature, few studies have examined the effects of qualitative characteristics on post-incubation performance and compiled industry-oriented knowledge on this issue that has not been provided (Tona et al., 2003(Tona et al., , 2005. In fact, not only CQ, care and feeding during the first week of life post-incubation are very important for high yield, with the form, digestibility and nutrient content of feed being particularly important (Garcia et al., 2006;Leeson, 2008). It is well known that a chick's digestive system at hatching is not yet well developed; enzyme activities are extremely low (Çelik and Açıkgöz, 2006). Therefore, it is thought that the nutrition provided to chicks during the first 5-7 days affects the growth performance and immune system and the feed given during this period should be highly nutritious and digestible to meet the nutrient demands of the animals and to promote the development of the gastrointestinal tract (Maiorka et al., 2006;Ebling et al., 2015). The present study was aimed to determine whether CQ (high and low) and providing pre-starter feeding during the first five days after incubation would affect fattening performance and carcass characteristics of broilers.

Ethical statement
This study was approved by the Çukurova University Animal Experiments Local Ethics Committee (Approval no: 2018/7).

Animals, diets and experimental design
One-day-old chicks (Ross 308) were obtained from a private hatchery following the standard incubation process for broilers according to Mcquoid (2000). Eggs used for hatching were obtained from the breeding flock at 62 weeks of age and the eggs were placed in the incubator after stored for 24 h. For the quality classification of the chicks at hatching, 1200 chicks were randomly chosen from the hatchery. After sexing based on wing feathers according to the Ross Recommendation (2018), a total of 800 chicks (400 male and 400 female) were selected according to the quality parameters (Table III) adopted in the study. The male and female chicks were divided into two treatment groups defined as high quality and low quality. Each quality group was divided into two feeding groups that received control feeding (CF) throughout the experiment or a pre-starter diet (PSF) for the first five days with control diets given for the remainder of the experiment. Thus, the birds were assigned to four treatment groups (2x2 factorial design feed and quality as main effects) including five replicates (20 males and 20 females in each) for each treatment. Since the nutrient requirements for the chicks changed according to age, the chicks were fed with three or four different feeds (prestarter and/or starter-grower-finisher) that had different pellet forms and nutrient content. Half of the chicks were fed with a PSF (Neochicc™ by Cargill, a commercial PSF designed with highly digestible foodstuffs (maizesoya-animal plasma) to aid the transition from yellow sac to solid feed after hatching). Approximately 100 g of Neochicc were provided to each bird for the first 120 h of life. Nutrient specification of Neochicc contains 23% crude protein, 9% crude fat, 2.65% crude cellulose, 6.3% crude ash, 0.95% calcium, 0.72% phosphorus, 0.20% sodium, 1.42% lysine and 0.66% methionine and it is specially designed in dust-free pellets with a diameter of 2 mm. The other feeds (starter , grower and finisher feeds, based on maize and soya) used in the trial were obtained from a commercial feed mill in pelleted forms with 3-4 diameters. The nutrient and ingredient composition of the feeds used in the experiment are given in Supplementary  Tables I and II. The birds were reared in an environmentally controlled house containing a total of 20 pens (3 × 1 m) with a 24-h daily lighting schedule. Feed and water were provided ad libitum throughout the experiment. Animal density in each pen was adjusted to 17 chicks/m 2 , similar to that applied in commercial conditions. During the experiment, the environmental temperature and humidity were maintained within the animal comfort zone using a curtain and tunnel ventilation systems according to the Ross Recommendation (2018).

Measurements and analytical methods
The quality of chicks were measured according to the criteria given in Table I and the quality score of the chicks was calculated by summing the scores of each parameter. Accordingly, chicks with a total score of 80-100 were considered to be high quality, chicks with a total score of 60-79 were considered to be low quality and chicks with a total score below 60 were classified as off-trail chicks. The weighted scores (30% for legs, 30% for eyes, 20% for feather color, and 20% for chick length) of these criteria were determined by evaluating leg structure, eye condition, feather color, and chick length. The importance level of each criterion for a healthy chick was taken into account in O n l i n e

F i r s t A r t i c l e
determining the weighted scores of the criteria used in the evaluation of CQ. The effects of the determining criteria on CQ were not individual and/or their relationships with each other, but the total effect of these criteria determined the CQ. The leg structure and eye condition of the chicks were evaluated by eye inspection, the feather color of the neck area was scored using the DSM-S yolk scale and the chick length was measured as the distance between the beak and the middle fingernail using a ruler (Supplementary Figs. 1 and 2).
The standard value ranges taken into account in the evaluation of chick length were determined by a preliminary study on a total of 200 eggs obtained from the breeding flock at 62 weeks of age.

Calculation and statistical analysis
Feed consumption was recorded weekly at the sub-group level, body weight (male and female birds separately) was measured each week by weighing on a digital scale. The feed conversion ratio (FCR) was calculated by dividing feed intake by body weight gains at the sub-group level.
Feed conversion ratio = (cumulative feed intake (g)/ cumulative body weight gain (g)) × 100 The number of dead birds was recorded daily by sex and assigned treatment groups. At the end of the experiment when the birds were 35-days old, all of the chicks were prepared for slaughter. Five male and five female birds having the average live weight of each replicate were used for the carcass analyses. Immediately after slaughter, the carcasses of the sample birds were weighed to obtain hot carcass values. The carcasses were then held in cold storage at 4°C for 24 h before the measurement of the cold carcass weight. The carcass yield was calculated using the following formula. At the same time, the abdominal fat weight was weighed and the relative abdominal fat weights were calculated using the following formula.
Carcass yield = (cold carcass weight (g)/slaughter weight (g)) × 100 Relative abdominal fat weight = abdominal fat weight (g)/cold carcass weight (g)) × 100 The data were analyzed using Statistical Analysis System (SAS) by 2x2 factorial design. Duncan's new multiple range test in SAS was used to identify significant differences among treatment means. The data related to liveability were calculated using Chi-square analysis with the help of SAS. The results obtained in this study are presented as means per bird with standard errors of the difference between means (SED). In addition, the significance level was taken as 0.05 in all tests.

RESULTS
Quality scoring for chick was applied to 1200 chicks and the rates of high, low and off-trial chicks were found to be 49.67%, 39.33% and 11.00%, respectively. The results obtained in the present study revealed that although the initial body weight was not taken as a parameter for CQ, the differences between the initial live weights of the quality groups were found to be significant (P < 0.05; Table II). According to this result, the mean initial body weights of the high-quality groups were found to be 1.33 g heavier than those of the low-quality groups and thus, the chicks having higher live weight classified as higher quality. Also, at the end of the experiment, the high-quality chicks were found to have 37.59 g more body weight gain than low-quality chicks (P > 0.05). It is thought that such as low as 1.33 g higher body weight at the beginning of the fattening period may create almost 37 g difference at the end of the fattening period. This may lead to more profitable production. But the differences in body weight gains of high and low-quality birds were not significant (P >0.05). It has been reported in many studies that chicks with a high live weight at the beginning of the fattening period  attained higher performance. When the groups fed with PSF for the first five days and the control groups were compared, it was observed that the groups fed with PSF had numerically higher live weights on the 7, 21 and 28 days. This result shows an increase in body weight gain and an improvement in the feed conversion rate in broilers fed with PSF at the weeks indicated. As shown in Table II, in terms of feed consumption, there was not a significant difference between the groups (P > 0.05). However, when the quality groups were evaluated individually, it was observed that the groups fed with PSF in the first 5 days consumed less feed during the experiment. The results concerning FCRs showed that there were no significant differences between treatment groups during the first two weeks of the experiment. However, FCRs calculated on the 3 rd and 4 th weeks of the experiment were found to be significant between the groups (P < 0.05; Table II). As the birds were getting older, the effects of CQ and PSF on the FCR were disappeared and become insignificant (P>0.05). On the 7 th , 14 th , 21 st , 28 th and 35 th days of the experiment, it was found that the mortality rate between the groups was not significant, as shown in Table  III (P > 0.05). However, it was observed that the mortality rate was lower in high-quality chicks for all weeks. Although the effect of PSF on mortality was not statistically (P > 0.05) significant, the group with the lowest mortality O n l i n e For abbreviations and statistical details see Table II. rate was observed to be high-quality chicks receiving the PSF. In general, mortality was observed to be lower in high-quality chicks, as it was expected. At the end of the trial, CQ and PSF application were found to have no significant effects on slaughter and carcass characteristics in male chicks (P > 0.05; Table IV). However, CQ was found to have significant effects on abdominal fat weight and abdominal fat ratio in female chicks (P < 0.05).

DISCUSSION
The results of the present experiment suggest that good quality chicks with a higher body weight after hatching may perform better than their low-quality counterparts. However, the relationship between the hatching weight of the chick and the slaughtering weight remains still unclear. However, Powell and Bowman (1964) speculated on a positive relationship between these two parameters; McLoughlin and Gous (1999), Wolanski et al. (2003) and Tona et al. (2004) reported no relationship between these two parameters. Contrary to our Vieira and Moran (1999) reported a negative relationship between the same parameters. McLoughlin and Gous (1999) found that there was no relationship between hatching weight and slaughter performance; however, they stated that chick weight at 7-10 days of age is closely related to slaughter weight. The beginning of the production period (especially for the first 5 days) is important for adaptation of the digestive system to exogenous feed-origin nutrients; chicks need highly digestible nutrients for growth, development of the immune system and thermoregulation (Maiorka et al., 2006;Ebling et al., 2015). Therefore, feeding chicks with PSFs that have a high nutrient content and/or digestibility during this transition period enables more efficient use of nutrients (Garcia et al. 2006;Leeson, 2008). In a study conducted by Leeson (2008), it was reported that the average live weights of chicks fed highly digestible PSFs instead of commercial corn and soy-based feeds increased from 160-170 g to 200 g. Tabeidian et al. (2015) reported that the addition of 0.3 L/kg water to PSFs prepared using casein-dextrose, casein-starch, gluten-dextrose and gluten-starch increased body weight gain of chicks. Nabizadeh et al. (2017) were investigated the effects on broiler performance of PSF prepared using four different levels of isolated soy protein (ISP; 0, 1.5, 3.0, 4.5%) and four different levels of broken rice (0, 6, 12, 18%). They reported that the bodyweight gains of the groups fed with PSFs were higher than the control group and that the body weight gain increased linearly with the increase of broken rice in the ration. The use of broken rice in pre-starter diets of broilers also had positive effects on body weight gains (Kita and Okuten, 2013;Ebling et al., 2015). Ivanovich et al. (2017) investigated the effects on broiler performance of PSFs having different metabolic energy (ME; 3,000 or 2,900 kcal/kg) and different digestible amino acids (DAA; 100%, 107%, and 114%) contents given during the first ten days. At the end of the study, they found that ME levels did not have a significant

O n l i n e F i r s t A r t i c l e
M. Durmuş and H.R. Kutlu effect on body weight gain; however, they reported an increased body weight gain in all periods of production parallel to the increase in DAA level. For optimal development of the chick digestive system after hatching, chicks should be stimulated to consume feed with the size of appropriate (pelleted) form, nutrients, and digestibility, as these factors significantly affect performance. In a study by Tabeidian et al. (2015), it was observed that feed consumption was increased in chicks fed with a PSF supplemented with gluten-dextrose. Another study on broilers by Bidar et al. (2007) examined the effects of PSF containing three different sodium levels (0.15%, 0.30%, and 0.45%) fed over different lengths of time (the first 4, 7 and 10 days) on broiler performance. Groups given PSF for 7 and 10 days during the first 2-weeks period consumed a higher amount of feed than those given the PSF for 4 days and control feed. In a similar study, Omede and Iji (2017) examined the effects of a pre-starter diet prepared in mash and cramble form using processed soy protein products (PSP) instead of soybean meal in the diet on broiler performance. They reported that during the first 24 days the birds received cramble feed consumed more than those of birds on mash, however, this effect was eliminated at the end of the experiment. It was also noted that PSP levels (0, 50 and 100 g/kg) used in the diet did not have a significant effect on feed consumption. Mahdavi et al. (2017) reported that the use of PSF during the first 10 days of feeding in broilers did not affect feed consumption. In another study, the difference in feed consumption between groups fed with alternative-doped (control+cassava starch, control+sucrose, control+corn gluten, control+blood plasma and control+corn gluten flour+sucrose) PSF and a control feed were not significant (Longo et al., 2007).
Our results suggest that the use of PSF during the first five days had no significant effects on feed consumption, supporting the findings of Mahdavi et al. (2017) and Longo et al. (2007). However, the results obtained in the present trial were also showed that the chicks on PSF consumed less amount than those of birds on control feed during all weeks. The reason for the low feed intake in the groups fed with PSF for the first 5 days is could be attributed to that birds could have reached the satiety with less amount of feed with the diet containing high nutrient digestibility. Pretorius (2011) suggested the use of highly digestible energy sources with high-quality protein sources in PSFs. Tabeidian et al. (2015) found that wetting of PSFs prepared using casein-dextrose, casein-starch, glutendextrose and gluten-starch with 0.3 L/kg water positively affected the FCR in all production periods. Besides, it was determined that feeding of wetted PSF containing caseinstarch improved the FCR. Ivanovich et al. (2017) investigated effects on broilers performance of the PSFs with two different metabolic energy (ME; 3,000 or 2,900 kcal/kg) and three different digestible amino acids (DAA; 100%, 107% and 114%) levels during the first ten days. They reported that at the end of the study, ME had no significant effect on feed conversion rate; however, the FCR in the first ten days was improved with the increase in the DAA level of ration. Mahdavi et al. (2017) examined the changes in the performance of broiler chickens fed with PSF in the first ten days. They reported that the use of PSF improved FCR but this positive effect disappeared by the end of the production period. The results of the studies examining the effects of PSF on the performance in broilers conducted by Lilburn (1998), Saleh et al. (1997 and Stringhini et al. (2003) are in agreement with those reported by Ivanovich et al. (2017) and Mahdavi et al. (2017). In contrast, Longo et al. (2007) found that the performance of chicks fed with PSFs prepared using highly digestible carbohydrates (cassava starch and sucrose) and proteins (corn gluten and blood plasma) did not significantly change. In similar studies conducted by Bidar et al. (2007), Ali and Latshawe (1994) and Junqueira et al. (2003) observed no significant effects of pre-starter diet on feed efficiency. The results concerning feed conversion efficiency suggest that highquality chicks had better FCRs than their low-quality counterparts. This finding could be attributed to better digestive capacity in high-quality chicks. The results also suggest that feeding with a pre-starter diet had more pronounced positive in low-quality chicks. This effect may relate to the higher digestibility of PSF. Therefore, especially in low-quality chicks, PSF led to numerically better FCRs throughout the experiment. Lamot et al. (2016) reported that deaths occurring before the 28 th day were related to the nutritional composition of the PSF and particularly, the delay in the time of the first feed consumption. In another study conducted in broiler, Cerrate et al. (2008) investigated the effects of PSFs with different pellet diameters (1.59mm, 2.38mm, 3.17mm and 4.76mm) on broiler performance and it was found that pellet diameters did not affect mortality. However, the optimum performance of the chicks in the first week was seen feeding by feeds with pellet diameters of 1.59 and 2.38mm because of the small size of the chick beaks. Mortality in the present study was seen to be lower in high-quality chicks, as expected. However, when the feeding groups of the low-quality chicks were compared, it was found that the mortality rate of chicks fed with the PSF was numerically higher than chicks fed with the control feed. Our results concerning mortality depending on pellet diameters of pre-starter and starter feeds seem to be compatible for high-quality chicks with the results of Cerrate et al. (2008). Ivanovich et al.

O n l i n e F i r s t A r t i c l e
Chick Quality and Pre-Starter Feed in Broilers (2017) reported from their studies investigating effects of PSFs having two different metabolizable energy (ME; 3,000 or 2,900 kcal/kg) and three different digestible amino acids (DAA; 100%, 107% and 114%) levels given during the first 10 days, found that total carcass weight, breast muscle weight and thigh weight in the first ten-day period increased with the increment of digestible amino acids levels in PSFs given for the first ten days. However, at the end of the experiment, they found that metabolizable energy, digestible amino acids and their interaction had no significant effects on the carcass characteristics such as carcass yield, thighs, wings and abdominal fat weights.
In another study, feeding with alternative-doped PSF (control+cassava starch, control+sucrose, control+corn gluten, control+blood plasma and control+corn gluten flour+sucrose) for the first 7 days, did not have a significant effect on carcass quantity and composition (Longo et al., 2007). Similarly, Mahdavi et al. (2017) reported that the use of PSF during the first 10 days of feeding did not affect slaughter weight and carcass characteristics such as carcass yield, breast, leg and wing weight. The results of the present study concerning carcass parameters support the findings of previous studies that examined the effects of PSF on broiler performance (Saleh et al., 1997;Rodriqueiro et al., 2000;Bidar et al., 2007;Longo et al., 2007;Azizi et al., 2011;Ivanovich et al., 2017;Mahdavi et al., 2017).

CONCLUSION
The results obtained from the present study suggest that approximately 100 g of PSF given per chick during the first five days after hatching had positive effects on broiler growth performance and feed conversion rate up to four weeks of age. The results also showed that high-quality chicks have 1.33 g more live weight at the beginning of the trial according to low-quality counterparts and provided an average of 37.59 g more body weight gain in total per chicken throughout the trial. In conclusion, it could be suggested that applying quality classification at hatching in broiler chicks with low quality could be off value for overall performance besides pre-starter feeding during the first five days after hatching for low or high-quality broiler chicks grown for grill up to 4 weeks of age.