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Eighty crossbred slaughter pigs [Duroc x (Landrace x Yorkshire)] originating from 20 litters were reared. In each litter there were two females and two castrates. Forty control pigs were given a standard grower-finishing feed, which mainly consisted of barley (55%), soybean meal (20%), wheat (20%), and sugar beet molasses (1%), and forty experimental pigs were given a diet with a low content of digestible starch, which consisted of high levels of grass meal (24%), rape seed cake (36%), dried sugar beet pulp (25%), soybean meal (7%), animal and vegetable fat (6%). Two pigs from each litter were slaughtered at high slaughter weight (live weight of 110 kg) and two pigs at low slaughter weight (live weight of 85 kg). This resulted in a 2 (feed) x 2 (sex) x 2 (slaughter weight) experimental design. The littermates were distributed equally according to sex and slaughter weight, but not as regards feed. The experimental diet was offered to the experimental group at a live weight of approximately 90 and 60 kg, respectively, with an initial 1-week adaptation period gradually changing from the standard grower-finishing diet to the experimental diet. The control pigs were given a standard grower-finishing diet during the whole experiment until slaughter. The feed withdrawal before slaughter for experimental pigs was 48 h, during which time the animals had free access to water. Pork colour was determined as the extent of blooming of M. Longissimus thoracis (LT) and M. semimembranosus (SM) after 1, 2, 4, 8 and 15 days post-mortem and as colour stability during a subsequent storage period in air for 6 days.
Compared to the control diet, the experimental diet resulted in a significantly lower post-mortem muscle temperature (1 ºC; P < 0.0001). Moreover, high slaughter weight (110 kg) resulted in a higher post-mortem temperature in LT (P < 0.001) compared to low weight (85 kg). Independent of feeding strategy and slaughter weight, the extent of blooming decreased during the first 2–4 days of aging in LT, however, the effect was more pronounced in meat from experimentally fed pigs and pigs with high slaughter weight. This effect was not seen in SM, where a gradual increase in blooming took place throughout the aging period. The colour stability was found to be superior in aged pork from experimentally fed pigs. The discoloration rate was faster in SM compared to LT.
In conclusion, the present study shows that the diet composition can be used as a tool to control meat colour and colour stability in pork.
K Tikk, G Lindahl, A H Karlsson, H J Andersen. 2008. Meat Science. 79:806-816
