Serum chemistry and gut morphology of two strains of broiler chickens to varying interval of post hatch feeding.

This trial was carried out to determine the responses of two broiler strains of chicken to different post-hatch access to feed. 180-day old chicks (Arbor acre and Marshal strains) with initial weight range of 39.36-42.24 g were used for this study. Each strain was divided on weight equalization into three treatment groups consisting of three time-periods with access to feeds (4 h, 24 h, 48 h) post hatch in a 2 × 3 factorial experiment after which they were fed ad-libitum. Thirty (30) birds were assigned to each treatment which comprised of three replicates of ten birds. Data collected on serum biochemical constituents and gut morphology were measured and subjected to analysis of variance in a randomized design. The Marshal strain recorded a higher (p < 0.05) final live weight (2420.00 g/bird) than the Arbor acre strain (2218.30 g/bird). Birds fed at 4 h and 24 h post-hatch recorded higher (p < 0.05) final live weights (2402.00 and 2391.00 g/bird) than those fed at 48 h post-hatch (2133.00 g/bird). Interaction effects showed that the Marshal strain fed at 4 h post-hatch had the highest (p < 0.05) final live weight (2594.00 g/bird). Highest (p < 0.05) serum total protein and albumin (37.3 and 22.8 g/l) were recorded in birds fed at 4 h post-hatch when assessed at 4 weeks of age. Furthermore, birds fed at 4 h and 24 h post-hatch recorded higher (p < 0.05) serum total protein and albumin than those fed at 48 h post-hatch. Birds fed at 4 h post-hatch recorded the highest (p < 0.05) duodenal villus height at 4th and 8th week of age and highest (P < 0.05) jejunal villus height when assessed in the 2nd week of age. It was concluded that Marshal strain fed at 4 h post-hatch elicited the highest growth performance and the most developed gut morphological features.

Introduction

Newly hatched poultry chicks do not have access to feed and water immediately for a 12–36 h period and are usually taken out of the hatchers when majority of chicks have hatched. Asides the operations of the hatchery, such as sex determination and vaccination, transportation to the production facilities are also responsible for a delay in access to feed. Broiler birds usually starts picking feed immediately after hatching for reasons of growth, but delayed feeding of chicks for 24–36 h may result in loss of body weight. To improve body weight and performance of chicks, the gut condition should rapidly develop since ithis is the key absorption site during digestion.

The early access of broiler chicks to feed has been reported to be of immense benefit to the survival of the chicks in the early stages of life (Batal & Parsons, 2002). Delayed feeding after hatching of chicks has also been found to negatively affect the intestine, causing a reduction in the development of villi and the rate of absorption of nutrients in the intestine including the impairment of growth, and development and expression of nutrient transporters responsible for dietary nutrient absorption. This in turn can affect the overall growth and performance of the chicks throughout the later phases of life (Yegani & Korver, 2008).

Furthermore, beyond the absorption of nutrients, it has also been observed that the immune status of birds could be suppressed by delayed access to feed during the early stages of life. The effect of this can be shown in blood and serum compositions (Dan, 2010). Chicks with suppressed immune status are prone to poor resistance to diseases and pathogens, and so show adverse effects on overall performance. We hypothesize in this study that different strains of broiler birds would react differently to different varying intervals of post-hatch feeding (Dan, 2010). It is of general knowledge in poultry production that it takes a while for chicks to be transported after hatch to the site of rearing. Over the years in Nigeria, farmers have lost a great number of young birds by not taking cognizance to the importance of early feeding of chicks post-hatch, as the birds may take up to 48 h to reach the farm, unfed. Therefore, this study chose to evaluate the effect of post-hatch feeding on some serum bio-chemical indices and gut morphology of two strains of broiler chickens at 4th and 8th week of age.

Materials and methods

Ethical permit

The practices adopted in this method were carried out according to the guidelines as approved by the project review committee of the College of Animal Science, Federal University of Agriculture, Abeokuta, Ogun state, Nigeria.

Experimental animals and management

A total of 180 broiler chicks, which comprised of two strains (Arbor acre and Marshal) were used for the study. Each strain group, consisting of ninety birds, was purchased from a hatchery in Abeokuta and raised on deep litter in separate pens for 56 days (8 weeks). On arrival, thirty (30) birds were assigned to each treatment group, made up of three replicates of ten birds, each group being housed individually. The rearing house and equipment were washed and fumigated thoroughly with formaldehyde and potassium permanganate solution two weeks prior to arrival of the birds. The chicks were floor brooded in groups for a period of two weeks, and the brooding temperature was maintained close to their standard broiler guide requirements. Standard routine vaccinations and medications including vitamins and antibiotics as prescribed by the hatchery were administered to the birds. Also, vaccines against Infectious Bursal Disease and Newcastle diseases were given at specified age intervals. The litter bedding was made up of dry wood shavings to help to prevent coccidiosis, and a high level of hygiene was maintained throughout the experimental period to ensure an environment conducive environment for growth. The birds were fed ad-libitum with commercial starter mash (0-4weeks) containing 2800 KcalME/Kg, 22%CP and finisher feed (5-8weeks) containing 3000 KcalME/Kg, 20%CP, which was purchase from a reputable feed mill in Abeokuta.

Growth performance

The body weight and feed consumption were monitored and recorded for each replicate weekly in other to determine the average feed intake, average body weight gain and feed conversion ratio of the birds. The birds were weighed on the first day of the experiment, then weighed weekly throughout the remaining experimental period. Feed was given daily and the leftover feed was weighed weekly to calculate the feed conversion data with equations as shown below:

Serum biochemical parameters

At the end of the 4th and 8th weeks of the experiment, 2.5 ml blood samples were obtained from two birds per replicate by neck decapitation into a syringe. The blood sample in the hypodermic syringe was allowed to clot before refrigeration for 6 h and later spun in a centrifuge at 900 rpm for 2 minutes. The separated sera was labelled for each bird, and stored in the freezer at −20 C prior to analysis. The serum was allowed to thaw under room temperatures before subsequent analyses. This Serum biochemical parameters (total protein, albumin, globulin, uric acid, and creatinine) according to standard methods (Schalm, 1986).

Gut morphology

At the end of the 4th and 8th week, a bird per replicate was selected for morphological analysis. Each bird per replicate was killed using an approved method, to collect the small intestine. The gastrointestinal tract was removed and separated into the three intestinal segments (duodenum, jejunum and ileum). The duodenum was taken distally from the gizzard to the end of the pancreatic loop, the jejunum was taken distally from the pancreatic loop to Meckel's diverticulum, and the ileum was taken from the Meckel's diverticulum to the ileo-caecal junction. A sample portion of 0.5 cm in length was taken from the middle portion of each of the three segments (Duodenum, Jejunum and Ileum) collected and placed into separate sample bottles containing 10% formalin for histological measurements. The samples were kept for 24 h in acetic acid/ethanol (25/75, v/v), after which it was rehydrated in a bath of ethanol/water (50/50, v/v) and then in distilled water. Thereafter, the samples were stained with the Feulgen reaction: hydrolysed in 1 N HCL at 60 °C for 6 min, it was rinsed three times with distilled water and stained with Schiff reagent for 30 min. The samples were rinsed in distilled water and stored in acetic acid/water (45/55, v/v) at 4 °C until further analysis. Intestinal villi with their crypts were separated individually under a dissecting microscope as described by Goodlad et al. (1991). The length and width of the villi were measured according to the procedure described by Hampson (1986) using an optical microscope and a camera.

Statistical analysis

All data obtained from the study were subjected to a Two-way Analysis of Variance using GLM procedures within SAS software (SAS, 1995). Statistically different means were separated using Duncan's Multiple Range Test (P < 0.05).

Results

There was no significant (P > 0.05) effect of strain and time of initiation of feeds on the growth performance parameters at 4 weeks of age (Table 1, Table 2). However, at 8 weeks of age, a significant (P < 0.05) effect of strain was observed on the final live weight of the broilers. The Marshal strain of broiler had a significantly (P < 0.05) higher final live weight compared to the Arbor acre strain of the broilers. Final live weight of the birds at 8 weeks of age was significantly (P < 0.05) affected by time of initiation of feed. The interaction of strain and time of initiation of feeds on growth of the finisher broiler indicated that Marshal strain of broiler fed at 4 h post-hatch recorded the highest final live weight while the Arbor acre strain of broiler fed at 48 h post-hatch recorded the least.

Table 1

Main effect of time of introduction of feeds (post hatch) and strain on growth performance of broilers at 4 and 8 weeks.

Parameter	Strain		SEM	P Value	Time			SEM	P Value
	AA	MS			4 h	24 h	48 h
0 – 4 wks
Initial weight (g/bird)	42.25	39.36	0.37	0.000	40.71	40.96	40.75	0.45	0.916
Final weight (g/bird)	873.40	843.86	12.83	0.845	881.02	851.10	800.90	15.75	0.920
Weight gain (g/bird)	831.15	795.94	12.86	0.845	840.20	810.05	760.10	15.78	0.920
Feed intake (g)	1472.00	1365.00	17.12	0.504	1417.00	1347.00	1343.00	20.97	0.378
FCR	1.77	1.60	0.27	0.404	1.59	1.55	1.71	0.33	0.723
5 – 8 wks
Final weight (g/bird)	2218.30b	2420.00a	13.28	0.040	2402.00a	2391.00a	2133.00b	16.26	0.024
Weight gain (g/bird)	1344.00	1576.14	16.28	0.834	1521.00	1540.00	1332.00	19.94	0.641
Feed intake (g)	3409.00	3811.00	47.07	0.142	3682.00	3605.00	3443.00	57.64	0.233
FCR	2.56	2.42	0.32	0.443	2.42	2.34	2.63	0.04	0.887

abcMean values in the same row having different superscripts are significantly different (P < 0.05).

Initial weight was used as covariate AA- Arbor acre MS- Marshal.

FCR: Feed conversion ratio PER: Protein efficiency ratio.

Table 2

Effect of interaction between time of introduction of feeds (post hatch) and strain on growth performance of broilers at 4 and 8 weeks.

Parameter	Arbor acre			Marshal			SEM	P value
	4hrs	24 h	48 h	4 h	24 h	48 h
0–4 wks
Initial weight (g)	42.17	42.58	42.00	39.25	39.33	39.50	0.64	0.843
Final weight (g)	864.70	863.40	894.70	907.61	813.70	709.73	222.28	0.998
Weight gain(g/bird)	823.90	822.60	852.70	866.80	772.90	670.23	22.27	0.998
Feed intake (g)	1533.00	1404.00	1490.00	1305.00	1129.00	1268.00	29.65	0.489
FCR	1.86	1.71	1.75	1.48	1.47	1.49	0.47	0.698
5–8 wks
Final weight (g)	2282.00b	2353.00bc	2026.00d	2594.00a	2285.00b	2244.00c	16.26	0.040
Weight gain(g/bird)	1417.00	1490.00	1132.00	1687.00	1571.00	1533.00	19.94	0.950
Feed intake (g)	3599.00	3340.00	3301.00	3835.00	3746.00	3762.00	57.64	0.506
FCR	2.54	2.24	2.92	2.25	2.38	2.44	0.04	0.905

abMean values in the same row having different superscripts are significantly different (P < 0.05).

Initial weight was used as covariate.

AA- Arbor acre MS- Marshal FCR: Feed conversion ratio.

Table 3, Table 4, Table 5, Table 6 revealed a significant (P < 0.05) increase in the value of serum uric acid as time of feeding was delayed. Serum creatinine levels were significantly (P < 0.05) different between birds fed at varying time with values increasing with delayed introduction of feeds post-hatch. The interaction of strain and time of introduction of feeds on the serum bio-chemical properties showed a significantly (P < 0.05) higher serum protein and lower globulin values in Marshal strain over and above Arbor-acre strain of broiler birds.

Table 3

Main effect of time of introduction of feeds (post hatch) and strain on serum chemistry of broilers at 4 weeks.

Parameter	Strain		P Value	SEM	Time			SEM	P Value
	AA	MS			4 h	24 h	48 h
Glucose (mg/dl)	216.89	226.67	0.196	5.053	230.50	223.83	211.00	6.18	0.118
Total Protein (g/l)	35.0a	29.0b	0.000	0.08	37.3a	30.5b	28.9c	0.10	0.000
Albumin (g/l)	20.0	17.7	0.110	0.10	22.8a	18.0b	15.8b	0.12	0.004
Globulin(g/l)	14.8a	11.3b	0.005	0.07	12.2	12.5	14.5	0.09	0.177
Alb/Glo	1.45	1.59	0.463	0.13	1.44	1.48	1.63	0.16	0.669
Uric acid (mg/dl)	2.63	2.62	0.932	0.14	2.23b	2.75a	2.90a	0.17	0.034
Creatinine (mg/dl)	0.47	0.58	0.89	0.05	0.38b	0.58a	0.63a	0.06	0.017
AST (Iu/L)	50.33b	53.67a	0.028	0.94	51.50	53.00	51.50	1.16	0.584
ALT (Iu/L)	25.17	27.33	0.308	1.44	24.25	25.75	28.75	1.76	0.225

Mean values in the same row having different superscripts are significantly different (P < 0.05).

AST-Aspartate amino transferase ALT- Alanine amino transferase.

Alb/Glo-Albumin/Globulin.

Table 4

Effect of interaction between time of introduction of feeds (post hatch) and strain on serum chemistry of broilers at 4 weeks.

Strain	Arbor	acre		Marshal			SEM	P Value
Parameter	4 h	24 h	48 h	4 h	24 h	48 h
Glucose (mg/dl)	213.67	221.67	215.33	247.33	226.00	206.67	8.75	0.084
Total Protein(g/l)	31.5bc	32.5bc	41.0a	25.0d	28.5cd	33.5b	0.14	0.480
Albumin (g/l)	16.5b	20.0ab	23.5a	15.0b	16.0b	22.0a	017	0.693
Globulin(g/l)	14.5ab	12.5bc	17.5a	10.0c	12.5bc	11.5bc	0.12	0.076
Alb/Glo	1.34	1.66	1.34	1.54	1.29	1.92	0.22	0.135
Uric acid(mg/dl)	2.30	2.90	2.70	2.15	2.90	2.80	0.24	0.868
Creatinine(mg/dl)	0.35c	0.55abc	0.50abc	0.40bc	0.70a	0.65ab	0.08	0.761
AST (Iu/L)	51.00bc	46.00c	54.00b	52.00b	60.00a	49.00bc	1.63	0.000
ALT (Iu/L)	21.00	25.50	29.00	27.50	26.00	28.50	2.49	0.348

abcdMean values in the same row having different superscripts are significantly different (P < 0.05).

AST-Aspartate amino transferase ALT- Alanine amino transferaseAlb/Glo-Albumin/Globulin.

Table 5

Main effect of time of introduction of feeds (post hatch) and strain on serum chemistry of broiler s at 8 weeks.

	Strain		SEM	P Value	Time			SEM	P Value
	AA	MS			4 h	24 h	48 h
Glucose (mg/dl)	188.78	201.33	14.46	0.551	206.50	180.17	198.50	17.72	0.574
Total Protein (g/l)	57.65b	60.02a	0.55	0.011	59.05a	60.70a	56.80b	0.68	0.005
Albumin (g/l)	32.75b	36.80a	0.64	0.001	37.38a	34.95a	32.00b	0.79	0.002
Globulin(g/l)	24.76	23.22	0.49	0.050	21.68b	25.48a	24.80a	0.60	0.002
Alb/Glo	1.33b	1.64a	0.05	0.000	1.80a	1.37b	1.29b	0.06	0.000
Uric acid (mg/dl)	4.04b	5.35a	0.11	0.000	4.55	4.84	4.70	0.13	0.323
Creatinine(mg/dl)	89.93b	105.18a	1.22	0.000	94.15b	100.50a	98.03ab	1.49	0.033
AST (Iu/L)	13.61b	22.33a	1.58	0.002	14.65	21.28	17.98	1.94	0.092
ALT (Iu/L)	13.7	14.3	0.02	0.072	14.0ab	14.7a	13.5b	0.03	0.044

Mean values in the same row having different superscripts are significantly different (P < 0.05).

AA- Arbor acre MS- Marshal; AST-Aspartate amino transferas; ALT- Alanine amino transferaseAlb/Glo-Albumin/Globulin.

Table 6

Effect of interaction between time of introduction of feeds (post hatch) and strain on serum chemistry of broilers at 8 weeks.

Strain	Arbor	Acre		Marshal			SEM	P Value
Parameter	4 h	24 h	48 h	4 h	24 h	48 h
Glucose (mg/dl)	208.33	165.67	192.33	204.67	194.67	190.67	25.05	0.811
Total Protein (g/l)	58.00	59.60	55.45	60.10	61.80	58.15	0.96	0.946
Albumin (g/l)	33.25bc	33.65bc	31.35c	41.50a	36.25b	32.65bc	1.11	0.020
Globulin(g/l)	24.75a	25.42a	24.10a	18.60b	25.55a	25.50a	0.84	0.002
Alb/Glo	1.37b	1.33b	1.31b	2.23a	1.42b	1.28a	0.08	0.000
Uric acid (mg/dl)	4.40b	4.23b	3.50c	4.70b	4.45a	5.90a	0.19	0.000
Creatinine (mg/dl)	89.25c	92.15c	88.40c	99.05b	108.85a	107.65a	2.11	0.109
AST (Iu/L)	14.80bc	13.07c	12.95c	14.50bc	29.50a	23.00ab	2.74	0.030
ALT (Iu/L)	13.5b	14.2ab	13.5b	14.5ab	15.0a	13.5ab	0.04	0.397

Mean values in the same row having different superscripts are significantly different (P < 0.05).

AA- Arbor acre MS- Marshal; AST-Aspartate amino transferase; ALT- Alanine amino transferase; Alb/Glo- Albumin/Globumin.

Furthermore, Table 7, Table 8, Table 9, Table 10 showed a trend as observed in gut morphology at 4 and 8 weeks of age of broiler chickens. Duodenal villus height and jejunal villus height decreased significantly (P < 0.05) with delayed access to feed, both at 4th and 8th week of age.

Table 7

The main effect of time introduction of feeds (post hatch) and strain on gut morphology of broilers at 4 weeks.

	Strain		SEM	P Value	Time			SEM	P Value
	AA	MS			4 h	24 h	48 h
DUODENUM
Villi height (μm)	1223.00a	1080.00b	23.05	0.001	1300.00a	1185.00b	970.00c	28.23	0.000
Crypt depth (μm)	163.33a	127.78b	7.74	0.007	160.00	126.67	150.00	9.47	0.074
Apical width (μm)	43.33b	56.67a	3.90	0.033	45.00	55.00	50.00	4.79	0.367
Basal width (μm)	86.67b	110.00a	6.27	0.022	125.00a	90.00b	80.00b	7.68	0.003
JEJUNUM
Villi height (μm)	906.67a	700.00b	29.63	0.000	1000.00a	930.00a	480.00b	36.29	0.000
Crypt depth (μm)	300.00a	144.44b	16.46	0.000	210.00	245.00	211.67	20.16	0.411
Apical width (μm)	43.33b	90.00a	4.67	0.000	65.00	75.00	60.00	5.71	0.209
Basal width (μm)	110.00b	150.00a	7.14	0.002	100.00b	150.00a	140.00a	8.74	0.004
ILEUM
Villi height (μm)	583.33b	663.33a	13.26	0.001	585.00b	650.00a	635.00ab	16.24	0.037
Crypt depth (μm)	180.00a	106.67b	10.00	0.000	110.00b	220.00a	100.00b	12.25	0.000
Apical width (μm)	93.33a	76.67b	4.81	0.031	65.00b	100.00a	90.00a	5.89	0.004
Basal width (μm)	150.00	133.33	667	0.102	110.00c	175.00a	140.00b	8.17	0.000

abcMean values in the same row having different superscripts are significantly different (P < 0.05).

AA- Arbor acre MS- Marshal.

Table 8

Effect of interaction between time of introduction of feeds (post hatch) and strain on gut morphology of broilers at 4 weeks.

Strain	Arbor	Acre		Marshal			SEM	P Value
Time	4 h	24 h	48 h	4 h	24 h	48 h
DUODENUM
Villi height (μm)	1400.00a	1300.00a	970.00b	1300.00a	970.00b	970.00b	39.93	0.000
Crypt depth (μm)	220.00a	120.00bc	150.00b	100.00b	133.33bc	150.00b	13.40	0.001
Apical width (μm)	50.00a	30.00b	50.00b	40.00b	80.00b	50.00b	6.77	0.002
Basal width (μm)	100.00b	80.00b	80.00b	150.00a	100.00b	80.00	10.87	0.109
JEJUNUM
Villi height (μm)	1200.00a	920.00b	600.00c	880.00b	940.00b	360.00d	51.32	0.005
Crypt depth (μm)	300.00ab	350.00a	250.00bc	120.00d	140.00d	173.33cd	28.51	0.087
Apical width (μm)	40.00b	50.00b	40.00b	90.00a	100.00a	80.00a	8.08	0.779
Basal width (μm)	100.00c	100.00c	130.00bc	100.00c	200.00a	150.00b	12.36	0.000
ILEUM
Villi height (μm)	600.00bc	500.00d	650.00b	570.00cd	800.00a	620.00bc	22.97	0.000
Crypt depth (μm)	100.00b	340.00a	100.00b	120.00b	100.00b	100.00b	17.32	0.000
Apical width (μm)	80.00	100.00	100.00	80.00	100.00	80.00	8.33	0.227
Basal width (μm)	120.00cd	150.00bc	180.00ab	100.00d	200.00a	100.00d	17.32	0.000

abcdMean values in the same row having different superscripts are significantly different (P<0.05).

AA- Arbor acre MS- Marshal.

Table 9

The main effect of time of introduction of feeds (post hatch) and strain on gut morphology of broilers at 8 weeks.

	Strain		SEM	P Value	Time			SEM	P Value
	AA	MS			4 h	24 h	48 h
DUODENUM
Villi height (μm)	960.00b	1154.00a	47.69	0.014	1242.00a	1000.00b	980.00b	58.41	0.008
Crypt depth (μm)	205.56	366.67	120.75	0.364	250.00	173.33	75.00	147.89	0.461
Apical width (μm)	36.67	40.00	3.66	0.532	35.00b	50.00a	30.00b	4.48	0.021
Basal width (μm)	90.00b	133.00a	8.39	0.003	90.00b	170.00a	75.00b	10.27	0.000
JEJUNUM
Villi height (μm)	988.89a	716.67b	71.47	0.020	900.00	850.00	808.33	87.53	0.764
Crypt depth (μm)	180.00	156.67	9.81	0.119	190.00	165.00	150.00	12.02	0.099
Apical width (μm)	46.67	53.33	4.81	0.347	45.00b	65.00a	40.00b	5.89	0.026
Basal width (μm)	93.33	100.00	10.91	0.673	100.00	110.00	80.00	13.34	0.306
ILEUM
Villi height (μm)	850.00a	624.44b	40.29	0.002	666.67	750.00	795.00	49.28	0.216
Crypt depth (μm)	253.33a	181.11b	17.07	0.011	245.00	216.67	190.00	20.91	0.219
Apical width (μm)	65.56	56.67	7.53	0.420	48.33	60.00	75.00	9.22	0.165
Basal width (μm)	100.00	100.00	10.97	1.000	100.00	100.00	100.00	13.44	1.000

abMean values in the same row having different superscripts are significantly different (P < 0.05).

AA- Arbor acre MS- Marshal.

Table 10

Effect of interaction between time of introduction of feeds (post hatch) and strain on gut morphology of broilers at 8 weeks.

Strain	Arbor	Acre		Marshal			SEM	P Value
Time	4 h	24 h	48 h	4 h	24 h	48 h
DUODENUM
Villi height (μm)	900.00b	1000.00b	980.00b	1483.00a	1000.00b	980.00b	82.61	0.030
Crypt depth (μm)	200.00	186.6	230.00	300.00	160.00	640.00	209.14	0.576
Apical width (μm)	30.00	50.00	30.00	40.00	50.00	30.00	6.35	0.670
Basal width (μm)	80.00	140.00	50.00	100.0	200.00	100.0	14.53	0.388
JEJUNUM
Villi height (μm)	1200.00a	1100.00a	666.67c	600.00c	600.00c	950.00ab	123.79	0.007
Crypt depth (μm)	200.00a	170.00ab	170.00ab	180.00ab	160.00ab	130.00b	16.99	0.676
Apical width (μm)	50.00	50.00	40.00	40.00	80.00	40.00	8.33	0.081
Basal width (μm)	100.00	120.00	60.00	100.00	100.00	100.00	18.89	0.306
ILEUM
Villi height (μm)	800.00	900.00	850.00	533.33	600.00	740.0	69.69	0.377
Crypt depth (μm)	300.00	280.00	180.00	190.00	153.33	200.00	29.56	0.056
Apical width(μm)	36.67b	60.00ab	100.00a	60.00ab	60.00ab	50.00b	13.03	0.043
Basal width (μm)	100.00	100.00	100.00	100.00	100.00	100.00	19.03	1.000

abcdMean values in the same row having different superscripts are significantly different (P < 0.05).

AA- Arbor acre MS- Marshal.

Discussion

In this study, it was observed that there was no significant (P > 0.05) effect of strain and time of initiation of feed on the growth performance parameters at 4 weeks of age but that the birds at the 8 weeks of age were significantly (P < 0.05) influenced by strain effect. This observation on the final live weight of the broilers might be attributed to the variation in the birds’ genetic make-up. The variation observed corroborated the report of Chadd (2008) who stated that broiler chicken performance is determined by the effect of a combination of genetic and environmental factors. The superior growth performance of the Marshal strain over the Arbor acre strain might be due to the superior genetic potential of meat yield of the Marshal strain of broilers which corroborates the report of Olawumi, Fajemilehin, and Fagbuaro (2012). Furthermore, the result sof the present study are consistent with the findings of Shahin and Elazeem (2005); Jaturasitha (2004) that broiler chicken live weight was strain dependent. Final live weight was significantly (P < 0.05) lower in birds having access to feed 48 h post-hatch. Similarly, Saki (2005) reported that body weight decreased in birds denied feed compared with birds fed earlier. The findings of this present study agreed with previous reports, which showed that delayed access to feeds post-hatch had negative effect on the performance of chicks (Bigot, Mignon, Picard, & Tesseraud, 2003; Gonzales et al., 2003; Saki, 2005).

The significant increase in value of serum uric acid as time of feeding was delayed suggested a protein wastage. Serum uric acid is a function of protein quality fed to the animal whereby high levels indicated low protein efficiency utilization (Fafiolu, 2007). Serum creatinine levels were significantly (P < 0.05) different between birds fed at varying time with values increasing with delayed introduction of feed post-hatch. Creatinine is a chemical waste molecule generated by muscle metabolism and the kidney is known to help in the maintenance of its range of normalcy (Umit, Derya, & Mustafa, 2011). However, the high creatinine value recorded in delayed fed birds is an indication of muscular wastage. The interaction of strain and time of introduction of feeds influenced the serum chemical properties which showed a significantly (P < 0.05) higher serum protein and lower globulin values in Marshal strain, thus suggesting a better utilization of protein in the diet.

The trend observed in gut morphology at 4 and 8 weeks of age of broiler chickens showed that duodenal villus height and jejunal villus height decreased significantly (P < 0.05) with delayed access to feed. This result corroborated the trend observed for growth performance in this study. Also the ileal crypt depth and apical width followed a particular pattern at the starter and finisher phases, where the Arbor acre strain showed a significantly (P < 0.05) higher value than the Marshal strain. The intestine, especially the crypts and villi of the absorptive epithelium, play significant roles in the final stages of nutrient digestion and assimilation (Liu et al., 2010). The crypt is the production site where divisions of stem cells occur to allow villus renewal. Hence, a deeper crypt suggests a fast cellular turnover to permit villus renewal which is needed in response to inflammation resulting from the effects of pathogens (Yason, Summers, & Schat, 1987). The higher duodenal and jejunal villi height obtained in this study with early fed birds suggested increased surface area capable of greater absorption of available nutrients (Caspary, 1992).

Greater villus height of intestinal segments is an indication of activation in the function of the intestine leading to higher potential capacity for absorption of nutrients (Yasar & Forbes, 1999). This study has indicated the existence of a direct relationship between the time of access to feed on villus height, which enhances the intestinal absorptive surface thus leading to a greater potential nutrient absorption (Panda, Shyam, Rama, & Raju, 2006). However, there were no consistent trends observed with the morphological characteristics of the duodenum, jejunum and ileum of the broiler chickens when considering the interaction effects of strain and time of access to feed

Conclusion

At the end of the experiment, it was concluded that the Marshal strain fed at 4 h post-hatch had the highest growth performance characteristics and the best developed gut morphological features.