D. Bochicchio

Use of pure glycerol in fattening heavy pigs.

Eighty Italian Duroc×Italian Large White pigs (BW 42.6±3.37kg) were used to determine the effects of pure glycerol on growth performance and meat quality of heavy pigs. Pigs were divided into five groups receiving 0% (control), 5% or 10% during the growing and finishing phases (42.6-160kg BW) (G+F5,G+F10) or 5% or 10% during the finishing period (100-160kg BW) (FIN5,FIN10) of pure glycerol in substitution for maize meal (on a dry matter basis). The pigs were slaughtered at approximately 160kg BW. The growth performance of pigs fed 5% glycerol did not differ from controls regardless of feeding duration, whereas those fed 10% glycerol showed reduced growth and poorer feed:gain ratio. Fat quality and meat suitability for raw ham curing were not affected by dietary treatment. Differences were not consistent enough to draw any conclusion about the effects of feeding glycerol on sensory characteristics.

Performance and fat quality of heavy pigs fed maize differing in linoleic acid content

Maize shows wide differences in linoleic acid due both to total lipid content and to fatty acid profile. Therefore, diets containing the same high maize percentage (up to 55%) can differ in linoleic acid content and lead to subcutaneous fats of differing suitability for raw ham curing. Two trials were performed on heavy pigs; in the first, 60 pigs (body weight 48.7+/-5.1 kg) were fed three diets made using three maize batches differing in linoleic acid due to different total lipid content, in the second trial, 40 pigs (live weight 70.4+/-3.4 kg) were fed two diets made using two maize batches differing in linoleic acid due to their fatty acid profile. Pigs were slaughtered at 170 kg of live weight. In both trials, the growth and slaughtering performance did not differ. In the first trial the three diets lead to a different content of linoleic acid both in subcutaneous (low linoleic vs medium linoleic vs high linoleic P0.01) and intramuscular fat (low linoleic vs high linoleic P0.05). In the second trial different linoleic acid content was observed for subcutaneous fat (P0.01) but not for intramuscular fat. To formulate diets for heavy pigs, it is crucial to know the linoleic acid content of the maize used, because differences of only 0.3% can lead to significant differences in fatty acids composition of depot fats.

Effect of feeding partially hydrogenated lard on trans-fatty acid content of muscle and backfat of heavy pigs

The incorporation of fat in diets for heavy pigs may be necessary in order to increase their energy intake in the finishing period. Lard may be a good lipid source but it contains 10-13% of linoleic acid, which makes the subcutaneous fat less suitable for long term curing of raw ham. Partial hydrogenation of lard decreases linoleic acid content, but increases trans-fatty acid content. This trial involved two groups of pigs of 114kg live weight, fed for the last two months before slaughter with diets containing 3% lard (L) or 3% partially hydrogenated lard (PHL). The PHL contained about 10% trans-fatty acids and 2.5% linoleic acid. Rearing performance and carcass characteristics were unaffected by treatment. The group fed PHL showed a lower percentage of linoleic acid in the backfat (PHL 12.28% vs. L 13.04%) and a higher percentage of C18:1 trans-fatty acids both in backfat (0.5% vs. 0.06%) and in intramuscular fat (0.2% vs. 0.04%).

Selective mobilization of fatty acids in adipose tissue of heavy pigs

The mobilization of fatty acids during food deprivation is a selective process studied in different species (humans, rodents, birds, viverrids). The aim of this work was to study the effect of fasting on selective mobilization in commercial pigs. A total of 16 barrows (Large White×Landrace (167 kg±12.5 kg live weight) were subdivided into two homogeneous groups, one subjected to 12 h and the other to 60 h of fasting (fasting time) before slaughtering. For each pig inner and outer backfat layer were sampled at slaughter and at ham trimming 24 h later (sampling time). Increasing the fasting time and the sampling time after slaughter caused an increase in the amount of free fatty acids in both layers. Therefore it can be argued that during fasting lipolysis is stimulated and remains active also after slaughtering. The factors that stimulate lipolysis determine a greater mobilization of unsaturated fatty acids than saturated ones. Thus fasting time may influence the suitability of pork for processing and conservation, since free fatty acids are more suitable for oxidation than the esterified ones.

Modification of lipid fraction in ensiled high moisture corn

The aim of this work is to study the changes of the lipidic fraction of ensiled high moisture corn (HMC). 11 maize hybrids were used, ensiled each in 3 mini experimental silos of 100 litres. For each hybrid 1 sample of fresh high moisture corn was obtained immediately after milling and 3 samples of ensiling HMC were kept after 2, 7 and 12 months. All samples were analysed for pH, dry matter, lactic acid, ammonia-N, ether extract, fatty acid composition and volatile fatty acids (VFAs). Ether extract of fresh high moisture corn was 35.7 g/kg dry matter (DM) and increased after 2 and 7 months of storage up to 39.4 g/Kg DM (P≤0.01); after 12 months it decreased to 38.1 g/kg DM (P≤0.01). Both saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) percentages decreased from 18.23% to 15.47% and from 24.84% to 23.57% respectively (before ensiling vs 12 months P≤0.01). Linoleic acid percentage increased from 55.34% to 59.44% (before ensiling vs 12 months P≤0.01). The linoleic acid content (g/kg of DM) increased on average from 19,1 before ensiling to 22.5 after 12 months of ensiling. These differences may affect the linoleic acid content of heavy pig diets when maize is used as HMC instead of corn meal.