FEEDING AND METABOLISM TRIALS, AND ASSESSMENT OF CARCASS AND MEAT QUALITY FOR GROWING-FINISHING PIGS FED NAKED OATS (Avena nuda)

Forty-eight Yorkshire pigs (barrows and gilts), about 24 kg body weight, were fed three diets: a control diet containing corn-soybean meal with minerals and vitamins added (Diet 0), the same diet in which naked oats (Avena nuda L. 'Tibor') replaced approximately 50% of the corn and soybean meal (Diet 50) and a diet containing 95.4% naked oats plus the mineral and vitamin supplements (Diet 100). The diets were pelleted and given ad libitum to the pigs which were penned individually until marketed at 90 ± 5 kg bodyweight. The left side of the carcass was used for carcass quality determinations, meat quality (sensory evaluation) assessment and backfat samples for fatty acid analysis. Eighteen other Yorkshire pigs were used in metabolism trials to determine digestible and metabolizable energy and nitrogen values and nitrogen balances when fed the three test diets. Energy values for urine were determined with freeze-dried samples combusted in polyethylene bags using an adiabatic bomb calorimeter. The diets (DM basis) contained about 18% crude protein and 18 MJ kg−1 energy; Diet 100 was higher in ether extract (5.5%) and lower in ADF (1.7%). Pigs fed Diet 50 gained weight faster than pigs fed either of the two other diets, the overall effect being accounted for mainly by differences shown by the barrows. Feed data showed a similar pattern with higher daily intake and fewer days to market for Diet 50 pigs. A lower yield of lean meat was obtained from pigs fed Diet 100, an observation also supported by increased depth of loin fat and carcass ether extract. The fatty acids palmitic, oleic and linoleic represented 12, 23 and 59% of the total in the control diet, compared with 18, 40 and 37% in Diet 100. This dietary change was reflected in a carcass decrease of linoleic acid from 14 (control) to 13% (Diet 100). The dietary level of naked oats had a significant and beneficial effect on sensory evaluation scores for the pork roasts; flavor, tenderness and juiciness scores were highest for pigs fed Diet 100. The apparent digestible energy value for Diet 100 (17.3 M J kg−1) was the highest as was the apparent metabolizable energy value (17 MJ kg−1). Correction of the AME for the energy of retained N reduced the value by 2.35%. The nitrogen retention value was approximately 10% lower for the 95.4% naked oat diet than for the corn-soybean control diet. The study indicated by feeding and metabolism trials that, although growing-finishing diets containing a high proportion of naked oats are likely to be of high energy and protein value, they are limited in feeding value by an amino acid imbalance due probably to lysine insufficiency. Key words: Naked oats, metabolism, carcass, meat quality, fatty acids, pigs