An investigation was made to alter the fatty acid composition of pork and a pork product in line with human dietary advice while not adversely affecting factors controlling consumer acceptability. Pigs (n = 150) were assigned to three dietary treatments with 25 intact male-female pairs per treatment. Diet A (control) contained 3% of a 4:1 (wt/ wt) tallow-soybean oil mixture. Diets B and C contained 2% rapeseed oil plus 1% fish oil. Diets A, B, and C were supplemented with 100, 100, and 250 mg of all-rac-alpha-tocopheryl acetate/kg of diet, respectively. Pigs were given ad libitum access to feed from 52 kg live weight until 95 kg (slaughter). Sausages were prepared from the resulting cuts. Tissues of pigs were evaluated in terms of fat firmness, color, fatty acid composition, and contents of alpha-tocopherol and thiobarbituric acid-reactive substances (TBARS). Organoleptic characteristics of chops and sausages were evaluated by a trained taste panel. Pigs fed Diets B and C had improved feed conversion ratios (P < .05) and ADG compared with control pigs. The levels of n-3 (omega-3) polyunsaturates were significantly increased in the tissues and sausage from pigs fed Diets B and C with associated alterations in n-6 to n-3 fatty acid ratios that accorded with contemporary human dietary recommendations. Levels of alpha-tocopherol and TBARS were significantly altered in the tissues. There were no appreciable differences between treatments in carcass characteristics, including color. The overall organoleptic acceptability of chops and sausages was not different between the treatments.

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1998). The effects of age at slaughter, genotype and nishing system on the biochemical properties, muscle bre type characteristics and eating quality of bull beef from suckled calves. AbstractMuscle fibre characteristics and biochemical properties of muscle recovered from young bulls of two genotypes (Aberdeen Angus Xand Charolais X), reared on two different diets (silage-based and barley-based) and slaughtered at varying ages between 10 and 19 months of age were established. These analyses were restricted to samples ofm. longissimus lumborum (LI) recovered at 48 h post mortem, vacuum packed and stored at 2°C for 14 days. Biochemical measurements included intramuscular fat content, intramuscular collagen content and its solubility, haem pigment concentration, sarcomere length and myofibril fragmentation. Muscle fibre type was classified according to the contractile nature of the fibres and their metabolic properties. Intramuscular fat content increased (P < 0-01) with age at slaughter and at a fixed age was greater for Angus X than Charolais X bulls (211-5 v. 295-8 mg/g dry matter, P < 0-01). Total intramuscular collagen and its solubility tended to decrease with age (P < 0-01). Differences in haem pigment concentration in samples of LI were detected between genotype (3-99 v. 3-59 mg/g for Angus X and Charolais X bulls; P < 0-01) and diet (3-97 v. 3-62 mg/g for bulls given barley and silage; P < 0-01), and increased with age at slaughter (P < 0-01). There was a significant increase in eye muscle cross-sectional area with increasing slaughter date (P < 0-01) and this was paralleled by an increase in cross-sectional area of individual muscle fibres (P < 0-001). Differences in cross-sectional area of individual muscle fibres between genotype and diet were small and inconsistent. Charolais X bulls had a greater percentage area of fast twitch glycolytic fibres than Angus X bulls (54-3 v. 49-3%; P<0-01) and a smaller percentage area of slow twitch oxidative fibres (15-8 v. 18-9%; P < 0-05). Beef tenderness was positively correlated (r = 0-48; P < 0-01) with the frequency of slow twitch oxidative fibres and negatively correlated (r = -0-38; P < 0-05) with the frequency of fast twitch glycolytic fibres.

A study was carried out involving 721 pigs, comprising boars and gilts, with either 0, 0.25 , or 0.50 Duroc inclusion level, which were produced by mating Large White boars with Large White × British Landrace sows, Large White boars with Duroc × (Large White × British Landrace) sows, or Duroc boars with Large White × British Landrace sows, respectively. Animals were reared on one of seven different feeding regimens from 30 to 90 kg live weight. Tissue growth rates were determined using a triple sampling procedure based on a combination of full-side and ham joint dissection on subsamples of pigs (127 and 366 pigs, respectively) and P2 backfat thickness on the remainder. Initial body composition was determined at 30 kg on subsamples of the three genotypes. Daily food intakes increased with increasing Duroc inclusion but live-weight gains were similar for the three genotypes. Lean and fat growth rates and food conversion ratios were greatest for the 0·50 Duroc group, although the genotype differences were small. Killing-out proportions and P2 fat depths were higher for the 0.25 and 0·50 Duroc groups. The proportion of lean in the carcass was lower (P < 0·01) for 0·50 Duroc pigs. Japanese colour scores and EEL reflectance indicated that the longissimus muscle was darker for the 0·25 and 0·50 Duroc genotypes. Subcutaneous fat firmness scores and penetrometer readings taken in the mid back indicated softer fat for the 0 Duroc group. Intramuscular fat levels increased (P < 0·01) with increasing Duroc inclusion (10.4, 11.2, and 18·2 g/kg for the 0, 0.25, and 0.50 groups respectively). Cooked longissimus from pigs with 0·50 Duroc had a lower shear force and was judged to have a stronger pork odour and to be more tender and acceptable than that from the 0 Duroc group. The 0.25 Duroc group showed a small improvement in tenderness but a weaker pork odour and similar overall acceptability compared with the 0 Duroc group. This study suggests that the use of the Duroc in crossing systems in the United Kingdom will have limited impact on growth performance but that 0·50 Duroc inclusion will result in fatter carcasses, higher intramuscular fat levels and improved eating quality.

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