Preliminary Investigation Of Broiler Pre-Slaughter Management And Effect Of Pre-slaughter Stress On Broiler Meat Quality

Broilers pre-slaughter managements which involves fasting, water withdrawal, transportation and lairage rest are the primary points for animal welfare and quality control. Otherwise, it also has significant impact on broiler meat quality. Countries with developed broilers processing industries have had intensive study of broilers pre-slaughter managements, and lain down operating norms for applying to industries. Currently, we pay no more attention to the effect of pre-slaughter management on broilers meat quality and are short of highly scientific operating specifications. This study had field and questionnaire surveys of26broilers slaughter and processing plants in12provinces or municipalities based on the situation of broilers pre-slaughter management (including fasting, water deprivation, transportation and lairage rest) both at home and abroad. Analyzed the present pre-slaughter management situation of broilers slaughter and processing in our country and researched the effect of transport time and lairage time collocation on broilers meat quality, proposes to provide references to formulate pre-slaughter management specifications for the broilers slaughter and processing industries.1. Preliminary investigations of broilers pre-slaughter managementsThe investigations used two manner:field surveys and questionnaire surveys. Survey objects were relevant person in charge of pre-slaughter management in26broilers slaughter and processing plants. Finally, we obtained22valid data. These plants distributed in southeast coast provinces and municipalities most in our country, like JIANG SU, SHAN DONG, SHANG HAI and so on. SHAN DONG province had a total of a quarter plants, was the most. Inland provinces or municipalities had the less. Seventeen plants which slaughtering capacity more than million reached77.2%of total,63.6%of total plants slaughtering capacity exceeded thousand. Nearly60%plants chose white feather chicken as their raw broilers, commonly used varieties were AA, Ross308,817broilers and so on. Broilers weight concentrate on2-2.5kg. The yellow feather chicken weight were generally smaller than the white which exceeded2kg mostly. The fasting time in each broilers slaughter and processing plants were8-12h most, same as the recommended values both at home and abroad, and14h was the longest. Water deprivation time had a larger span,12plants chose1-3h as their water deprivation time reached54.5%of total was the most. Five plants chose4-6h and3plants chose7-9h, in addition, other2plants had no water deprivation. Transport time and density had large differences in these plants according to their own situation. Transport mortality rate was generally low, about0.1%. The lairage rest time in most plants were lower than2h, only1plant chose8-10h.2. The effect of transport time and lairage rest time on broilers meat qualityAccording to the effect of9treatments which included2factors and3levels of transport time (0.5h,3h,5h) and lairage rest time (0h,1h,2h) on broiler meat color, pH, water retention, tenderness of18042-day-old AA broilers, found the reasonable match of transport and lairage rest time to improve broilers postmortem quality. From the results,1h postmortem L*(L*first) had an upward trend as transport time extended in each lairage rest time period. After5h transport time the L*first of Oh and1h lairage rest time were significantly higher than other transport time treatments (P<0.05). The a*first of each transport time treatments increased and then decreased as the lairage rest time extended and all reached the hightest at3h lairage rest. There were no significant effect of transport and lairage rest time on b*first.Among each transport time period24h after postmortem L*(L*end) decreased and then increased as lairage rest time extended. The trends of L end in each transport time period were the same with L*first, but reached the hightest after5h transport and higher than other transport time treatments obviously (P<0.05). The a*end had an downward trend as transport time extended in each lairage rest time period and0.5h transport time treatments were significantly higher than other twos (P<0.05). The b*end increased and then decreased as transport time extended in each lairage rest time period. After0.5h transport pHfirst and pHend gradually increased both as lairage rest time became longer, but as transport time extended, pHfirst and pHend of0h and1h lairage rest time decreased gradually. Among1h lairage rest time treatments pHfiret and pHend after0.5h transport were higher than other transport time treatments. Drip loss value had an upward trend as transport time extended in each lairage rest time period. Drip loss of no lairage rest treatment was higher than2h lairage rest obviously after5h transport (P<0.05) and was the highest among all treatments. Effect of transport and lairage rest time on cooking loss were not significant (P>0.05) except for the treatment with3h transport and1h lairage rest which was higher than others (P<0.05). Shear force value of0h and2h lairage rest treatments became higher as transport time extended and the value after3h transport and1h lairage rest was the highest. From the result of the effect of transport time and lairage rest time on broiler meat quality, after0.5h transport need0-1h lairage rest; after3h transport need about2h lairage rest; after5h transport need about1h lairage rest as recommended.3. The effect of transport and lairage rest time on broilers plasma stress parametersThe Glucose (GLU) concentration had an downward trend as transport or lairage rest time extended. After5h transport, Lactic acid (LD) concentration became lower as lairage rest time extended and the treatment with no lairage was the highest among all treatments. The Corticosterone (CORT) and Adrenocorticotropic hormone (ACTH) concentration of3h transport were higher than0.5h and5h treatments revealed a high degree of stress. Difference of the two hormones each was not significant of0.5h transport treatments and5h transport treatments indicated that the long time transport brought in stress adaptation. After3h transport Lactate dehydrogenase (LDH) and Creatine kinase (CK) had the largest activities and strongest stress. The two enzymes activities not decreased as lairage rest time became longer indicated that the activities not decreased as the relief of stress in a short time. From the result of the effect of transport time and lairage rest time on broiler plasma stress parameters, after0.5h transport need no more than2h lairage rest; after3h transport need about2h lairage rest; after5h transport need about1h lairage rest as recommended.