EFFECT OF POST HATCH DELAYED ACCESS TO FEED ON PERFORMANCE , GIT PHYSICAL AND HISTOLOGICAL DEVELOPMENT AND YOLK ABSORPTION IN YOUNG BROILER CHICKS

The effect of post hatch starvation on growth rate, feed intake, feed conversion ratio, yolk absorption, and small intestine morphological index and gastrointestinal tract (GIT) organs relative weight were evaluated in young broiler chicks. Two hundred and twenty five newly hatched male "Ross-308" broiler chicks were placed in three treatments with five replications of 15b each. The experiment was arranged in a complete random design (CRD) at 6, 12 and 18 hours delay access to feed immediately after hatching as treatments. Body weight and weight gain increased significantly in birds that had access to feed with 6h delayed compared with those at 12 and 18h delayed access to feed. The total gastro intestinal tract and small intestine relative weight and small intestine length numerically decreased with increased delayed access to feed. The highest small intestine relative weight and length were observed in birds that started to feed at 6h after hatching and the lowest weights were observed in birds that started to feed at 18h after hatching. Also, the highest villus height, villus width and apparent villus surface area were observed in birds that started to feed at 6h after hatching. The results of this study revealed that delayed access to feed has adverse effects on broiler performance. Therefore, be recommended that transportation plan have to be provided to chicks to reduce starvation time after hatching.


INTRODUCTION
In commercial broiler farm, it has been shown that the neonatal chicks remain approximately 24-36h without feed and water after removal from the incubator until placement in the farm (Bhuiyan et al. 2011; Willemsen et al. 2010), this gap between hatching time and neonatal chick's access to feed due to hatchery handling and transport processing (Noy and Sklan 1999a).This delay access to feed after hatching results in a lowering of development and function of the gastrointestinal tract (GIT) (Potturi et al. 2005;Yang et al. 2009), thereby undesirable bird performance (Gonzales et al. 2003) such as reducing final body weight (Noy et al. 2001), decreasing immune response (Dibner et al. 1998), retarding growth and increasing mortality (Gonzales et al. 2003; Willemsen et al. 2010).Because of delays in placement chicks are often subjected to delayed access to feed which may retard the development of the GIT, limiting nutrient utilization and performance of the broiler chicken (Uni et al. 2003).Early access to feed after hatching stimulates rapid growth of the GIT and its absorptive capacity, improves chick's immune system and faster utilization of yolk suck (Bhuiyan et al. 2011) and improves gut integrity (ýNoy and Sklan 1999a; ýMoran et al. 1990).Therefore, it is extremely important for the chicks to consume feed as close to hatch as possible.Although, hatchery feeding (ýKidd et al. 2007; ýWillemsen et al. 2010) and in ova injection (ýUni and Ferket 2004) suggested to reduce the detrimental effects of such delay access to feed but those are practically difficult to achieve (ýLilburn 1998).Early access neonatal chick to feed as reduced transport time to the poultry farm with purchase chicks from local hatchery is most important applied clue to overcome the detrimental effects of such starvation.Hence, this study was designed to evaluate the effects of different delayed times access to feed on the performance, yolk absorption and physical development of the digestive system in young broiler chicks.

Birds, Housing and Care
A total of 225 neonatal commercial "Ross 308" male broiler chicks were obtained from a local hatchery and were transported to the study area within 6h after hatched.The chicks were divided into three groups; each group was further divided into five pens of 15 chicks each.The chicks were raised on conventional deep litter system, with windows less house, equipped by inlet for ventilation.Each pen was 1.5 squares meter and covered with wood shavings.The house temperature and humidity were initially maintained at 35-37ºC and 60-70% respectively and after 3 days gradually decreased (temperature 0.5ºC every day and humidity decreased 50-60%).From 1 to 42 d of age, the lighting program was constant (23 Light: 1 Dark) with 25-35 lx light intensity.The chicks in each pen were allowed to have free access to feed from a handing feeder and fresh water from a handing drinker throughout the experiment.The whole house work includes house cleaning, adding new food and fresh water did daily.

Experimental Design and Diets
The experiment was arranged in to a completely randomized design (CRD) experiment of three groups include done starved birds for 6, 12 and 18 hours after post hatching.Each group was further divided into five replicates per treatments with 15 birds per each.Diets were formulated according to the recommended nutrients by Ross 3.8 manual for broiler chickens and were offered in mash form.The composition of the diet is presented in Table 1.The water was offered ad-libitum to the birds from 1 to 42 d of age.

Performance Measurements
Live body weight and feed weighed in and weighed back per pen were measured in a period of 0-12 days of age.Weight gain, feed intake and feed conversion were calculated.Daily chick mortality were recorded for the calculation of feed intake and feed conversion during the experimental period.

Slaughter, Sampling and Histological Measurements
At 0, 2, 4, 8 and 12 d of age, one birds/ pen, close to the average pen weight was selected, weighed and slaughtered.The digestive tract, from the pro-ventriculus to the end of the intestine, was excised.The crop, pro-ventriculus and gizzard were emptied and weighed.The small intestine was divided into three segments: duodenum (from gizzard to pancreo-biliary ducts), jejunum (from pancreo-biliary ducts to Meckel's diverticulum), and ileum (from Meckel's diverticulum to the ileo-caecal junction).Then, the total segments of small intestine and large intestine were emptied and weighed.After clearing the intestinal contents, a portion (about 0.5 cm in length) of the small intestine segments was taken from the midpoint of each segment, flushed with 0.9% saline to remove the contents and then were fixed in 10% neutral buffered formalin solution for histological study.
Intestinal samples were transferred from formaldehyde, after dehydration by passing tissue through a series of alcohol solutions, were cleared in xylene and were embedded in paraffin.Intestinal samples were sectioned at 5 µm thickness using an auto microton 1 .These samples were placed on glass slides, and were prepared and processed for staining with Hematoxylin and Eosin (H& E) and Vangieson.All chemical were purchased from sigma chemical company.
Micrographs were taken with an Olympus microscopic 2 , BX41 (Olympus, Tokyo, Japan).Morphometric measurements were performed on 9 villi chosen from each sample.Morphometric indices included were villus height (VH) from the tip of the villus to the crypt, crypt depth (CD) from the base of the villi to the submucosa, villus width (VW; average of VW at one-third and two-third of the villus) and muscular thickness (MT) from the submucosa to the external layer of the intestine (ýGeyra et al. 2001).Apparent villus surface area (AVSA) was calculated by the formula (1): Formula 1: Where AVSA is apparent villus surface area, VW is villus width and VH is villus height (Solis et al. 2007ý26).

Statistical Analysis
The data were tested for effects of starvation for 6, 12 and 18 hours.Analysis of variance was performed using a complete randomized experimental design.All percentage data were transformed to arc-sin by the formula (2) before statistical analysis.All data were analyzed by ANOVA using the GLM procedure of the SAS 9.1 software (SAS 2003).Means were compared for significant differences using Duncan Multiple Range test (P<0.05).Formula 2: Where X is transformed date and x is percentage

Performance
The mean of initial body weight of newly hatched chicks was 37.56 ± 0.65g and chick's pen weight were similar before they were allocated to the treatment.The average body weight (BW) at the end of 10d of age, daily body weight gain (DBWG) and daily feed intake (DFI) and feed conversion ratio (FCR) during 1-10d of age of broiler chickens are shown in Table 2.The BW and DBWG of birds fed at 6h post hatch were significantly (P<0.05)superior to those on 12 and18h fasting.The observed lower DBWG in the 12&18h fasted chicks during the first 10d of life is consistent with reports by (ýSaki 2005) in which delayed access to feed decreased broiler post-hatch performance.Lower DBWG exhibited with increasing fasted period (12&18h) could be attributed to lower feed intake and poor development of digestive tract.Early access to feed and water may improve the feed/ gain ratio and affect feed intake of broilers during the first two weeks while a short period of feed restriction (12 h) at the time of placement could impact the growth performance and feed intake of broilers during the starter phase (ýRashed 2011).Geyra et al. (2001) reported that when feed consumption starts soon after hatch, the nutrients provided by feed are complementary to the yolk nutrients and this will trigger rapid growth rate in birds.Initiation of feed consumption as close to hatch as possible is essential to support early muscle development, which may ultimately affect meat yield.That feeding of broiler in the first days of life is one of the priority factors that could affect BW, DBWG, feed efficiency, uniformity and economic benefit.

Residual yolk and gastrointestinal tract relative weight
The average relative weight as a percentage of live body weight (%LBW) of different sections of the gastrointestinal tract (GIT) and small intestine length of chicks that were measured at 1, 2, 4, 8 and 10d of ages are shown in Table 3 and 4 respectively.Although, the difference of the residual yolk relative weight between the three experimental groups was not significant (P > 0.05), during 48h of post hatch, residual yolk relative weight of birds in the all groups decreased, while the decrease rate in birds that feed with 6h delayed was more rapid than fasted birds for 18h.This result is consistent with the previous study (ýNoy and Sklan 2001).Early feeding after hatch, compared to delayed feeding, appears to stimulate yolk utilization (Noy and Sklan 1998a; ýSpeake et al. 1998).Moran (1989) and Pinchasov and Noy (1993) reported depriving chicks of feed for 18 h post-hatch led to reduced uptake of residual yolk and greater yolk weights than was observed with chicks given immediate access to feed and water (ýMoran 1989; ýPinchasov and Noy 1993).Murakami et al. (1992) reported yolk weight decreases 48 to 41% per day for fed and feed-deprived broiler chicks, respectively.Upon examination of the rate of residual yolk utilization, hatchlings subjected to delayed access to food or water showed that the use of the yolk is retarded in comparison to 'Earlyfed' birds, this may be due to increased intestinal mechanical (antiperistaltic) activity (ýNoy et al. 1996).In the immediate post-hatch period, yolk was used for maintenance and for intestinal growth (ýNoy and Sklan 1999a).This requirement possibly led birds to use their body reserves to supply the nutritional requirement for survival, which resulted in body weight reduction.Yolk is utilized for preferential early growth of the small intestine, which occurs both in the presence and in the absence of feed although in the absence of feed both absolute and relative growth is lower (ýNoy and Sklan 1999b).The importance of the residual yolk was emphasized in the study of Swennen et al. (2009) as the residual yolk appeared to be of high importance when chicks were fed diets with different macronutrient content.Chicks fed the low protein diet showed the highest utilization of the yolk during the first two days.

Ingredients
The GIT organs relative weight were significantly (p<0.05)different between birds fed with 6h delayed compared to birds fed with 12 and 18h delayed after hatching.The GIT organs relative weight and small intestine length numerically decreased with increased delayed access to feed time.Significantly better development of GIT and higher duodenum, jejunum and ileum relative weights indicated a slight tendency of better GIT development in chicks that fed 6h delayed posthatch opposite to birds fed with 12 and 18h delayed.The negative effect of fasting on performance traits was related to inadequate development of the GIT, particularly of the duodenum and jejunum, at a very early stage of postnatal life (ýKuhn et al. 1996).Initiation of feed consumption as close to hatch as   Murakami et al. (1992) found that delaying access to feed and water slowed the growth of the small intestine and pro-ventriculus in broiler chicks.Noy and Sklan (1997) concluded that one effect of delayed placement on both chicks and poults was that the organs of the GIT (crop, small intestine, and large intestine) grew less by 48 h post-hatch than did organs of chicks placed immediately on feed and water.

CONCLUSION
In conclusion, because of delays in placement chicks are often subjected to delayed access to feed and water, which may retard the development of the GIT, limiting nutrient utilization and performance of the broiler chicken.Early access to feed and water after hatch has shown to be an important factor for subsequent performance.Therefore, delayed access to feed adversely affects chicks' performance.In this experiment we found that holding feed time for 6h v until 18h is compensated by increasing the broiler performance.It is recommended that transportation plan be provided to chicks to reduce starvation.

Table 2 : Effect of delayed access to feed of post-hatch on performance index; body weight at 12d, daily body weight gain, daily feed intake and feed conversion ratio in the during 1-12d of age of broiler chickens
a, b Means with no common superscripts in each column are significantly different (P < 0.05)