Effect of a new high fibre feed on blood biochemistry of outdoor finished male local pigs

Abstract

This work, within the framework of ECO-PIG Project, measured the effects of a high soluble dietary fibre feed on blood biochemistry parameters in outdoor raised Portuguese Alentejano (AL) male pigs (n=30) with access to ad libitum water and feed. Surgically castrated (group C) and intact pigs (groups I and IE) were fed commercial diets from 40 to 130kg body weight. From 130 until 160kg (slaughter), groups C and I were fed commercial feeds while group IE ate the isoproteic and isoenergetic experimental diet, including agro-industrial by-products. Blood samples were collected at 120kg (before the start of the fattening period) and two days before slaughter. Serum levels of total protein, urea (U), glucose, triacylglycerols (TG) and cortisol (COR) were determined. At 120 kg, U levels were different among the groups (3.3±0.2 in IE, 4.0±0.2 in I, and 5.0±0.1 mmol/L in C pigs, p<0.001). At 160 kg, they were different between IE and C groups, again with lower values in intact pigs (3.1±0.2 in IE, 3.4±0.3 in I, and 4.0±0.2 mmol/L in C pigs, p=0.034). These overall lower U levels in intact pigs suggest a more efficient nitrogen use for lean tissue growth than in castrates. TG levels were lower in intact pigs at 160kg (0.30±0.03 in IE, 0.37±0.04 in I, and 0.53±0.04 mmol/L in C pigs, p<0.001). Higher blood TG levels relate with fatter pigs, and C pigs produced fatter carcasses than intact ones (see “The ECO-PIG project: Use of a new high fibre feed for outdoor finishing of intact male local pigs”). Finally, COR levels at 160kg were lower in IE than in I and C pigs (79±13 in IE, 272±38 in I, and 204±22 nmol/L in C pigs, p<0.001). This suggests lower stress levels on the IE group and agrees with the number pigs with of skin injuries related to agonistic interactions observed in the last week of trial (4 in IE, 8 in I and 9 in C pigs). Further studies will test the effect of the experimental feed on pork boar taint and meat quality of intact AL pigs raised outdoors.