Effects Of Stunning, Withholding Food And/or Water Methods And Storage Temperatures On Meat Quality Of Rex Rabbit

Some major factors which influence rabbit carcass and meat quality were studied inthis paper, based on present situation of rabbitry's breeding and processing in our country.Three main parts were included here: Firstly, effects of stunning methods on meat qualityof Rex rabbit; Secondly, effects of withholding food and/or water methods on meat qualityof Rex rabbit; Third, effects of storage temperatures on meat quality of Rex rabbit.Results were listed below:1. The meat quality was studied after Rex rabbit stunned in 100V (voltage),75V,65V,55V electrical stunning and manual stunning (stick stunning). The results showed:There was not significant difference between the effect of meat pH₂₄ (pH for 24 hour afterslaughter) with different stunning methods (p＞0.05), but the rabbit pH_LD1 (the rabbitlongissimus lumborum muscle pH for 1 hour after slaughter) was significant differencebetween 75V and 100V electrically stunned groups. The difference was not significantabout the effect of different stunning methods on rabbit LD muscle color L*-value(lightness),a*-value,b*-value and rabbit BF (biceps femoris) muscle color L*-value,a*-value for 1 hour after slaughter. Then 24 hours after slaughter, the 100V electricallystunned group was significantly lower than the 75V and 65V electrically stunned groups(p＜0.05) on LD muscle a*-value, the 75V electrically stunned group was significantlyhigher than the 65V and 55V electrically stunned groups (p＜0.05) on BF muscle a*-value.24 hours after, slaughter, the muscle color of 75V electrically stunned group was fresh red,but 100V electrically stunned and manual stunned groups were pale. The drip loss of 100Velectrically stunned group was highest (3.738%). The drip loss of 75V electrically stunnedgroup was lowest (2.420%). The cooking loss of 100V electrically stunned group washighest, that of 55V electrically stunned group was lowest and 75V electrically stunned group was lower. The tenderness of 75V electrically stunned group was best, that ofmanually stunned group was worst.2. The rabbits were maintained under four different conditions, before slaughteringthem and analyzing their meat: food and water withheld 12-18 h before slaughter (Group 1);food withheld for 12-18 h, but water available ad libitum (Group 2); food available adlibitum, but water withheld for 12-18 h (Group 3); food and water available ad libitum(Group 4). The pH of meat 1 h postmortem (pH_1h) was not different among the treatmentconditions (p＞0.05), though the pH at 24 h postmortem (pH₂₄) varied significantly betweenGroups 1 and 2 and Groups 3 and 4 (p＜0.05); in general, pH₂₄ increased following fasting.Withholding food or water decreased the lightness (L*-value) of meat after storage for 24 h.Group 2 had the highest redness value (a*-value). Drip loss, ripe meat ratio, and tendernesswere affected greatly by withholding water, more so than by withholding food. Groups 2and 4 had a lower drip loss and Warner-Bratzler shear value but a higher ripe meat ratiothan Groups 1 and 3. Group 2 had the lowest drip loss and Warner-Bratzler value, and thehighest ripe meat ratio. Water content and intramuscular fat (IMF) were not affected by thetreatment conditions (p＜0.05). The best quality rabbit meat can be obtained by withholdingfood for 12-18 h before slaughter, but allowing access to water ad libitum.3. Changes of physical, chemical and microbial indexes of rabbit meat were measuredon different storage temperature(4℃, 15℃and 25℃). Data showed that different storagetemperature had significant effect on pH, drip loss, TVB-N, TBARS and microbialindexes(p＜0.05). Compared with low storage temperature (4℃), rabbit meats had short pHreascended time, higher drip loss and TVB-N value as well as quicker progenitive rate ofmicrobe when they were storaged on high temperature(25℃). Rabbit meat color was alsoaffected by temperature and the oxidative rate of rabbit meat was ascending followed byincreasing storage temperature which resulted in the decrease of a*-value, increase of L*-value and discoloration. Low storage temperature(4℃) restrained the oxidative process, sorabbit meat color can maintain a long period and TBARS value was lower. Tenderness ofrabbit meat declined after slaughter, then it increased slowly. Different temperaturetreatment affected tender process significantly after rigor mortis (p＜0.05): Aging rates ofrabbit meat on moderate(15℃) or high(25℃) temperature condition were rapider than thatof low(4℃)temperature condition, but the latter had better meat quality after a slowly acid excluding period. Chilled meat(4℃) had the longest shelf life (6 days), compared with 15℃for 3 days and 25℃for only one day. Generally consideration, it is reasonable tostorage rabbit meat on low temperature(4℃).