The aim of this study was to compare the effect of stocking density on growth performance and slaughter traits of two different commercial broiler strains. A total of 600 birds (300 Hubbard and 300 Ross 308) were grouped in two stocking density for each strain (12 and 18 birds/m2 ). Body weight was recorded at the beginning of the study and then on weekly intervals. Feed intake was calculated at the end of each week. At the end of the trial, 20 birds from each strain-density combination were chosen randomly to evaluate slaughter traits. Data were analyzed using the mixed procedure of SAS, strain, density, and their interactions were treated as fixed effect. While group was treated as random effect. No differences (P < 0.05) were detected among all growth traits. For slaughter traits. Dressing percentage was higher for the 18 birds/m2 Ross308 compared to 12 birds/m2 Hubbard. Breast and leg cut percentages did not show any significant differences among all groups. Stocking density is known to have a significant effect on growth and carcass parameters, however, the results of this study showed the opposite. This could be due to the timing of the study were temperatures were moderate during day and night time.
Keywords: stocking density, strain, broiler
The improvement of genetic selection and management practices are increased dramatically for the last decades (Kryeziu et al., 2018), stocking density of broilers is one of the major factors that can improve performance to face the improvement of genetic selection (Simsek et al., 2011).
Stocking density has a significant impact on production cost, however, excessive density may affect broiler performance and thus slaughterer traits. Slaughter traits are affected by stocking density by allowing birds to have access for feeders and drinkers because this will influence the target market weight.
Since Jordan has different strains of broiler chicken and with the absence of recommended of stocking density, the main objectives of the present study are: Investigate the difference in growth performance and slaughter traits between two broiler strains under commercial conditions. To investigate the effect of bird’s density on growth performance and slaughter traits.
Material and Method
The experimental procedures were all approved by the Institutional Animal Care and Use Committee of Jordan University of Science and Technology (JUST). The trial was conducted at the agricultural research and training unit at JUST. A total of six hundred birds were randomly grouped according to their strain and stocking density in a 2 × 2 factorial arrangements (two strains, 300 birds Ross 308 and 300 birds Hubbard classic; and 2 stocking density 12 (normal) and 18 birds/m2 (crowded)). The experiment lasted for 35 days, all birds were weighed upon arrival, and then on weekly basis. Birds were all fed commercial diet (table 1) with adequate space for birds on feeders and drinkers, feed and fresh water were offered as ad libitum, and refusal feed was weighed at the end of each week.
At the end of the trial, 4 birds were taken randomly from each group (20 birds/strain-density) and their fasting live weight was recorded then birds were slaughtered following the Halal method by cutting carotid artery and jugular vein. After bleeding, birds were scalded at 54°C for 120 sec; feather was removed in a rotary drum picker for 40 sec, and manually eviscerated. Carcasses were then chilled for 6 h at 5°C, then carcass weight, dressing percentage and cuts percentages were measured and recorded.
Data collected were analyzed using the PROC MIXED procedure of SAS (SAS Inst., Inc., Cary, NC). Models included strain, density, and their interaction as fixed effects, while bird group was modeled as random effects. Level of significance was determined at alpha 0.05, the Tukey-Kramer mean separation test was used to determine differences between means.
Table 1. Experimental diet
Research Findings and Discussion
Averages of birds feed intake and corresponding standard error are presented in table 2. No effect (p > 0.05) of genetic group and stocking density were detected. These findings are similar to a study conducted by Siaga et al., (2017) and showed there was no significant of stocking density when Ross 308 and Cobb were used. The results may be attributed to enough spacing per bird in both feeders and drinkers.
Table 2. Total feed intake during the three experimental stages
Feed conversion ratio of all experimental groups are presented in table 3. In general, values were numerically better for Normal stocking density groups but was not significant from crowded groups values. Siaga et al., 2017 have similar findings on FCR when they evaluated Ross 308 and Cobb Avian.
Table 3. Feed conversion ratio
No significant differences were detected among all experimental units for body weight gains table 4. Results are similar to a study conducted by Gosh et al., 2012, and showed that no significant on body weight when increased the stocking density per birds compared to control at 42 days of age.
Table 4. Total body weight gains during the three experimental stages
Dressing percentage was higher (P < 0.05) for the 18 birds/m2 Ross compared to 12 birds/m2, while the other two groups were intermediate.
Table 5. Slaughter traits
Results and Suggestions
The results of this study show that increasing stocking density could be beneficial for broiler operations when the weather is suitable and temperatures are moderate. However, caution must be followed when the temperatures rise above the thermoneutral zone.
The authors would like to thank the Deanship of Scientific Research at Jordan University of Science and Technology for the financial support of this project.
Presented at the International Congress on Agriculture and Forestry Research, Marmaris, Turkey.