Improving Meat Quality of Culled Dairy Cows with Feed Regime and Post-mortem Handling

Abstract

This study was separated into three experiments. The first experiment was evaluating the effect of finishing strategies with different agro-industrial by-products on growth performance of culled dairy cows. Culled dairy cows (n = 32) were kept individually and allotted to one of four treatments. A control group (C) was slaughtered immediately after culling-off. All others were subjected to a finishing period of 12 weeks. A forage group was fed with ad lib corn silage (F). Additionally there were a high-energy group (6 kg/day of cassava pulp + ad lib corn silage; F+) and a low-energy group (6 kg/day of rough rice bran + ad lib corn silage; F-) both based on by-products. Cows fed with corn silage had the lowest average daily feed intake (10.64 vs.11.21 and 12.11 kg DM/d; P = 0.001) respectively, the highest feed : gain ratio (27.79 vs. 21.65 and 25.67; P = 0.087)), respectively and tended to have the lowest ADG (0.38 vs. 0.51 and 0.51 kg/h/d), respectively. No treatment effect was found on average carcass percentage, carcass length, lean percentage, carcass fat percentage, bone percentage, loin eye area and KPH percentage among groups. The second experiment was evaluating the effect of agro-food industry by product on meat quality of culled dairy cow. The LD sample from Experiment 1 was individually excised 24 h post-mortem and stored at –20 °C prior to analysis. There were no significant effects of finishing treatment on meat color of all groups. Drip, thawing and cooking losses were not statistically different between groups. The meat of C had significantly higher percentage of protein and tended to have more moisture than the other groups. Meat of the group F+ had the highest contents of fat and cholesterol. There was no significant effect by treatment on Warner-Bratzler shear force although shear force tended to be lowest with F+. The meat’s contents of soluble and insoluble collagen were not significantly different among treatment groups. The content of palmitic acid (C16:0) was significantly highest (P=0.015) in F+ group when compared with the other groups. Arachidonic acid content was higher for culled dairy cows forage compared with F+ group (1.71 VS. 0.98 mg/100g of meat) and 1.45 mg/100g of meat in F - group, respectively. The content of docosahexaenoic acid was highest in F group (0.42 mg/100g of meat), 0.21 mg100g of meat in F + group and 0.13 mg/100g of meat in F - group. The third experiment was to evaluate the effects of ageing and calcium chloride injection on beef longissimus dorsi quality traits. LD beef were injected (10% by weight) with 250 mM CaCl2 solution. Non - calcium chloride injected served as ageing treatment. The both of minolta colorimeter L* and a* values for LD were affected (P<0.05) by storage time. L* value abounded but a* value declined (P<0.05) as increasing storage time. Calcium chloride injection were affected (P<0.05) only a* and b* values for LD. Calcium chloride treatment had lower a* value than Non-injected treatment since first day of storage, and declined as storage time increased (P<0.05). Drip loss values were affected by calcium chloride injection from day 3 onwards. Additionally increasing the day of storage time caused increasing drip loss values regardless of ageing beef. Calcium chloride injection did not affect on thawing loss and cooking loss values. The TBA-reactive substance (TBARs), expressed as mg of malonaldehyde per kg of meat. Lipid oxidation (TBARs) was increased significantly (P<0.05) in both of treatment as time increased. The average TBARs values of non-injected group were lower than injected group. Shear force value were statistically analyzed considering both treatment. Shear force value of injected sample decreased on the third day of storage (P<0.05). The myofibrils fragmentation index (MFI) increased (P<0.05) steadily throughout storage time. And also, the MFI values of calcium chloride injection were greater (P<0.05) than ageing treatment. Sensorial characteristics of beef treated with calcium chloride were evaluated on each cook meat after different periods of ageing. Sensory panel score for juiciness and off-flavor intensity increased (P<0.05) comparing ageing with the injection.