Effects of finishing diet and pre-slaughter fasting time on meat quality in crossbred pigs

The effects of the carbohydrate composition of finishing diet (fed from 80 to 107 kg of body weight) and the length of pre-slaughter fasting on pork quality were studied in a 2 × 2 factorial experiment with 80 crossbred pigs. The control finishing diet was based on barley and soybean meal, and the fibrous finishing diet was based on barley, barley fibre, faba beans, and rapeseed cake. These diets contained 465 and 362 g starch and 177 and 250 g dietary fibre per kg, respectively. The fasting times of 25 and 41 h were obtained by giving the pigs their last meal at different times. Longer fasting lowered the glycolytic potential of the longissimus lumborum muscle (P = 0.01), whereas the finishing diet had no effect. Different muscles responded differently to the treatments. Longer fasting increased the ultimate pH of the semimembranosus muscle (P = 0.02), but did not affect that of the longissimus lumborum and semispinalis capitis muscles. The finishing diets did not affect the ultimate pH of the investigated muscles. A diet × fasting time interaction was seen in the lightness of the semimembranosus muscle (P = 0.05). The fibrous diet resulted in darker meat than the control diet did in pigs that were fasted for 25 h (P < 0.05). Longer fasting darkened the meat colour in pigs fed the fibrous diet (P < 0.05) but not in those fed the control diet. The meat from the semispinalis capitis muscle was darker in pigs fed the fibrous than those fed the control diet (P = 0.04). The treatments did not affect the colour of the longissimus lumborum muscle. Longer fasting decreased drip loss from the meat of pigs fed the control diet (P < 0.05). The eating quality of the pork was not influenced by the finishing diets or the fasting time. The pigs also grew equally fast on both finishing diets. In conclusion, a moderate alteration in the carbohydrate composition of a finishing diet or longer pre-slaughter fasting can have some effects on pork quality in crossbred pigs, but these effects vary in different muscles.