In Pakistan, livestock contributes 58.6% to agriculture and 11.6% to overall GDP. While, total meat production is 3873 thousand tonsannually from which beef contributes 56% of it. Most of the red meat is being exported to the Middle East countries. Globally, Pakistan is competing with other countries by slaughtering of young animals. Because processor thinks that meat quality is only affected by the age of animal. While, ignores the other factors like post-slaughter chilling rate and ageing time that also affect the meat quality attributes. Therefore, objective of the present study was to investigate the effect of age (18 and 26 months), post-slaughter chilling rate (delayed and rapid) and ageing time (7 days and 14 days) on meat quality traits of M. longissimus dorsi (LD) of cattle and buffalo calves.
In this experiment 48 animals were selected (24 were cattle calves out of which 12 were 18 months and other 12 were 26 months of age; other 24 were buffalo calves out of which 12 were 18 months and other 12 were 26 months of age). After slaughtering, carcasses were splitted into two halves, one for delayed and another for rapid chilling. Temperature and pH were taken at intervals of 0, 1, 2, 4, 7, 18 and 24 hours post slaughter. After overnight chilling and achieving the rigor mortis, both strip-loins were deboned and cut down into nine steaks. Nine strip-loin steaks from each treatment (delayed and rapid chilling) were processed at 1, 7 and 14 days of ageing. Thereafter, striploins were evaluated for meat quality attributes like color, tenderness, purge loss and cooking loss %.
The results of the present experiment showed that cattle age at slaughter showed a significant effect on warner-bratzler shear force (WBSF) values. Bulls with age of 18 months were tender than 26 months of age. Because, collagen starts depositing within muscles as the age of the animal advances, which is a major factor of texture of cooked meat. Meat redness (a*) and chroma (C*) values were higher at 18 months of animal age. While, buffalo meat showed a
non-significant effect of animal age on WBSF values. Moreover, cooking loss percentage was also increased with the advancement of animal age.
In both species, chilling rate significantly affect the WBSF values of LD muscle of 18 months old animals. While, effect of the chilling was non-significant at 26 months of animal age. This could be due to lighter weight and leaner carcasses at 18 months of slaughtering age and were unable to hit the pH/temperature window and faced the cold shortening. Whereas only in cattle calves, hunter L* and a* values were affected by rigor temperature and recorded higher during delayed chilling of carcasses from 18 month old animals. While, chilling rate showed a non-significant effect on cooking loss percentage.
Similarly, in 7 and 14 day aged strip-loin steaks, WBSF values decreased significantly at 18 and 26 month of animals’ age in both cattle and buffalo calves. The rate of tenderization decreased as storage time increased and recorded a 79 and 82 % reduction in WBSF values during first 7 days in meat of cattle and buffalo calves respectively. The improvement in tenderness during storage of steaks could be attributed to the degradation of myofibrillar and associated proteins with help of endogenous protease enzymes. Likewise, all color parameter values were also improved with the storage of meat in 18 and 26 month old animals of both species. In the same way, cooking loss and purge loss percentage values increased linearly with ageing of meat.





CONCLUSION
Based on the findings of the present study it can be concluded that:
There is no obvious difference of meat quality between the animals of 18 and 26 months of age in cattle and buffalo. Thus, instead of early age slaughtering, animals should be raised at least up to two years of age, which may help to increase in overall meat production of the country.
Immediate after slaughtering, rapid chilling of beef carcasses leads to toughening of meat.The effect is more obvious in 18 month old animals in both species. So it is suggested that, pre-chilling or electrical stimulation of carcasses should be exercised rather than rapid chilling in order to elude the chances of cold shortening.
Ageing of striploin steaks improves the tenderness and color of the meat. Effect ismore pronounced during first 7 days of storage. Therefor ageing should be practiced within Pakistan in order to compete globally.Secondly, as beef is being exported by air with high airfreight charges. If this meat is shipped by sea after vacuum packaging at 0⁰C, it may decrease the transportation cost and its ageing will also be done because it takes around 7 days to reach Middle East countries. While in case of other destinations, it will take even more time for shipment.