Anna-Marie Lynch

Effects of restricted feeding and antioxidant supplementation on pig performance and quality characteristics of longissimus dorsi muscle from Landrace and Duroc pigs

The present study was designed to evaluate the effects of compensatory growth diets with or without antioxidant inclusion (α-tocopheryl acetate (TA) or green tea catechins (GTC)) on pig performance and quality characteristics of longissimuss dorsi (LD) muscle from Landrace or Duroc pigs. Breed did not influence pig performance but had a significant effect on pork quality. Duroc muscle had higher intramuscular fat, ash and monounsaturated fatty acid levels and lower levels of moisture compared to Landrace. Lipid and pigment oxidation levels were higher in meat from Landrace pigs at initial stages of the study. Pigs fed restricted diets had reduced growth rates and lower back fat thickness. Decreasing the duration of energy restriction or significantly increasing dietary energy prior to slaughter resulted in compensatory growth. Supplementing diets with α-TA increased α-tocopherol levels in m. LD. Lipid oxidation levels (TBARS values) remained low throughout refrigerated storage. Dietary treatments did not affect colour stability or compositional analysis. Overall, lipid oxidation was highest in meat from pigs fed diets with greatest energy restriction and lowest in meat from pigs fed diets supplemented with α-TA or GTC.

Use of high pressure liquid chromatography (HPLC) for the determination of cda-tocopherol levels in forage (silage/grass) samples collected from different regions in Ireland

First, second and third cut grass silage samples were collected from eight regions around Ireland (184 samples in total) and analysed for vitamin E content. Fresh grass samples were also collected at one site in Co. Cork and analysed for α-tocopherol content. The concentration of α-tocopherol [μg/g dry matter (DM)] was determined using high performance liquid chromatography analysis. A wide variation in α-tocopherol levels in silage samples was found. α-Tocopherol levels in first, second and third cut silage samples ranged from 4.9 to 20.8, 4.4 to 13.0 and 1.3 to 3.9 μg/g DM, respectively. The mean values of α-tocopherol in first, second and third cut silage samples were 11.3±0.9, 9.7±0.7 and 2.3±0.5 μg/g DM, respectively. There was no significant difference in α-tocopherol levels between first and second cut silage samples. However, third cut silage samples had significantly (P meadow grass>hedgerow>white clover>red clover.

Distribution of α-tocopherol in beef muscles following dietary α-tocopheryl acetate supplementation.

The objective of this study was to determine the effect of dietary vitamin E supplementation on the distribution and concentration of α-tocopherol in beef muscles. Crossbred cattle (n=8) were selected and divided into two groups and fed diets containing 20 (basal) and 3000 mg (supplemented) α-tocopheryl acetate/head/day for 135 days prior to slaughter. Carcasses were split centrally and chilled at 4°C for 10 days. Muscles (n=16) were identified and removed from the left side of each animal and stored at -20°C until required. Mean α-tocopherol levels in muscles were significantly (P<0.05) higher in all supplemented muscles with the exception of m. infraspinatis and m. deltoidous compared to controls. Mean α-tocopherol levels in muscles from the supplemented group decreased in the order m. supraspinatis > m. psoas major > m. trapezius > m. gluteus medius > m. triceps caput brachii lumborum > m. rhomboidous > m. seratus ventralis > m. gluteobiceps > m. semitendinosus > m. semimembranosus > m. infraspinatis > m. subscapularis > m. tricepscaputbrachiilaterale > m. deltoidous > m. longissimus thorasis > m. longissimus lumborum. Significant (P<0.05) differences in α-tocopherol distribution within muscles were observed for supplemented m. psoas major and control m. seratus ventralis (highest levels in posterior ends and lowest in anterior ends) only. However, trends showed definite distribution patterns for other muscles. Levels of α-tocopherol were found to be highest in oxidative muscles (m. psoas major and m. gluteus medius) and lowest in glycolytic muscles (m. longissimus thoracis and m. longissimus lumborum) while moderate levels of α-tocopherol occurred in intermediate muscles (m. semimembranosus).