| In summer, pre-slaughter transportation will make the broilers suffer from transport and heat stress, which not only threatens the welfare of broilers, but also affects the postmortem meat quality, caused economic losses in broiler processing industry in China. The developed countries in Western have had intensive study on broilers pre-slaughter transportation and put into practice in broiler processing industry. However, such a research is rare in our country and many broiler processing industries do not attach much weight to it. This study made a thorough inquiry of the effect of transport time on breast meat color and pH value of broilers in summer by investigating three large processing plant in our country; in addition, analyzed the effects of transport and rest on broiler stress and meat quality in summer to find suitable rest time for different transport time; furthermore, we had a research on the effect of pre-slaughter showering and ventilation treatments on stress, meat quality and metabolite concentrations of broilers following transportation in summer in order to provide data and references to broiler processing industries.1. Investigations in broiler processing industries in ChinaThe aim of this study was to investigate the effects of different transport time on broiler breast meat color and pH value of broilers in summer. The birds were 42-45 days old white feather broilers chosen from three large commercial slaughter plant in China, which were A plant, B plant, C plant. Broilers were slaughtered following 0.5 h,1.5 h,3h transportation and 100 breast fillets were obtained from every transport group at 1.5 h postmortem to measure the L*,a9, b* and pH value. The ambient temperature when transporting was 34-36℃. It’s determined that transport time had a significant influence on L* value (P< 0.05); Compared with 1.5 h and 3 h transportation group, the L* value in 0.5 h transportation group was significantly higher (P< 0.05); in plant A and C, the pH value was significantly higher with prolonged transport time (P< 0.05). In all the three plants, the occurrence of lighter meat was highest in 0.5 h transportation group, and the occurrence of darker meat showed an increasing trend with prolonged transport time. In addition, a highly significant negative correlation was found between L* value and pH value (P< 0.05). According to the results of our study, the 0.5 h transportation in summer may cause an increased occurrence of PSE-like meat in broilers, and the broiler processing industries should avoid 0.5 h transportation in summer.2. Effects of transport and rest on broiler stress and meat quality in summerIn order to investigate the interaction effects of transport and rest on broilers stress and meat quality in summer, total 189 white feather broilers were assigned to 9 treatments randomly. The study design included three transport time (0.5h,3h and 5h, respectively) and three rest time (Oh, 1h and 2h, respectively), and analyses of adreno-cortico-tropic-hormone (ACTH), corticosterone (CORT), creatine kinase (CK), L*, pH, drip loss, cooking loss, lactic acid, glycogen were performed after broilers were slaughtered on commercial line. The results showed that ACTH, CORT, CK, pH values increased with prolonged transport time (P< 0.05), however, L* value, drip loss, cooking loss, muscle lactic acid and glycogen showed the contrary trend with increasing transport time (P< 0.05). Meanwhile, ACTH, CORT, CK decreased with prolonged rest time (P< 0.05), which had an insignificant influence on the rest of indicators (P> 0.05). Factorial analysis results showed that transport time had a highly significant effect on all indicators (P< 0.01). Rest time had an insignificant effectiveness on all indicators (P> 0.05), except ACTH and CORT. Interaction between transport time and rest time affected CORT,1 h L*, drip loss,and cooking loss significantly (P< 0.05), however, it’s impact on other index was not significant (P> 0.05). In a conclusion, the transport in summer would result in broiler stress, which was adverse to meat quality. Reasonable transport time with proper rest time would relieve broiler stress and improve meat quality.3. Effects of pre-slaughter showering and ventilation treatments on stress and meat quality of broilers following transportation in summerThe aim of this study was to observe the effects of showering and ventilation treatments following transport during summer on stress, meat quality and energy metabolism of broilers. Arbor Acres broilers (n= 84) were randomly divided into 4 treatment groups:1) control group without ventilation or showering (C),2) 10 min ventilation without showering (VWS),3) 10 min showering without ventilation (SWV),4) 5 min showering and then 5 min ventilation (SV). Compared with control group, plasma LDH activities in the other three treatment group were significantly (P< 0.05) lower, and plasma CK activities in the SV group were significantly (P< 0.05) lower, whereas the plasma glucose concentrations did not show any significant changes among the groups. Moreover, the breast meat in the SV group had significantly (P< 0.05) higher pH24h and glycogen contents and had lower L* values, ApH, drip loss, cook loss, R-value and lactate content than the control group. However, there was no significant difference in shear force values (SFV) among any of the groups. According to the results of our study, broilers in SV group showed a lower stress level and improved meat quality, which suggests that the combined action of showering and ventilation after transportation may be a good measure to relieve the transport and heat stress and improve the meat quality of broilers during summer. |
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