Addition of grape seed extract and bearberry to porcine diets: Influence on quality attributes of raw and cooked pork.

The effect of supplementation of pig diets with grape seed extract (GSE) (100, 300, 700mg/kg feed) and bearberry (BB) (100, 300, 700mg/kg feed) for 56 days pre-slaughter, on the oxidative stability and quality of raw and cooked M. longissimus dorsi (LD) was examined. Susceptibility of porcine liver, kidney and heart tissue homogenates to iron-induced (1mM FeSO(4)) lipid oxidation was also investigated. In raw LD steaks, stored in modified atmosphere packs (75% O(2):25% CO(2)) (MAP) for up to 16 days at 4°C, surface lightness (CIE 'L' value), redness (CIE 'a' value), lipid stability (TBARS, mg MDA (malondialdehyde)/kg muscle) and pH were not significantly affected by supplemental GSE or BB. Similarly, the oxidative stability and sensory properties of cooked LD steaks, stored in MAP (70% N(2):30% CO(2)), for up to 28 days at 4°C, were not enhanced by dietary GSE or BB. Iron-induced lipid oxidation increased in liver, kidney and heart tissue homogenates over the 24h storage period and susceptibility to oxidation followed the order: liver>heart>kidney. Dietary GSE or BB did not significantly reduce lipid oxidation in tissue homogenates. Potential reasons for the lack of efficacy of supplemental GSE and BB on pork quality were explored.

Efficacy of cleaning and disinfection on pig farms in Ireland.

Little is known about the effectiveness of the cleaning and disinfection methods used on commercial pig farms either in Ireland or worldwide. A National Salmonella Control Programme was implemented in Ireland in August 2002 to monitor and control the infection of pigs with Salmonella species. Commercial pig herds must be categorised according to their Salmonella status as either category 1, 2 or 3, having a serological prevalence of infection with Salmonella serotypes up to 10 per cent, between 10 and 50 per cent or more than 50 per cent, respectively. The aim of this study was to assess the efficacy of washing and disinfecting finisher units on category 1 and category 3 farms in reducing or eliminating the levels of contamination. Counts of Enterobacteriaceae were used as indicators of the contamination of the environment with enteric bacteria, which could include Salmonella species. Samples were taken from the pen floors, feeders and drinkers of seven category 1 and seven category 3 farms, and Enterobacteriaceae and salmonellae were enumerated in each sample. The results suggested that intensive cleaning and disinfection was effective at reducing levels of Enterobacteriaceae on the pen floors of both categories, but that residual contamination remained on the surfaces of the feeders and drinkers on all the farms, particularly on the category 3 farms.

Market potential for probiotics.

"Functional foods" as a marketing term was initiated in Japan in the late 1980s and is used to describe foods fortified with ingredients capable of producing health benefits. This concept is becoming increasingly popular with consumers because of a heightened awareness of the link between health, nutrition, and diet. Food manufacturers are enthusiastic about developing such products because the added ingredients give increased value to food. The global market for functional foods in the coming years is predicted to grow rapidly. Although Japan currently accounts for about one-half of this market, the fastest rate of growth is expected to be in the United States. Probiotic products represent a strong growth area within the functional foods group and intense research efforts are under way to develop dairy products into which probiotic organisms such as Lactobacillus and Bifidobacterium species are incorporated. Such probiotic foods may modulate gut microbial composition, thereby leading to improved gut health, for example, through improved tolerance to lactose in lactose-intolerant individuals or improved resistance to pathogenic bacteria. Large numbers of viable microorganisms are likely to be required in the food product, which should be consumed regularly to experience the health effect. The probiotic market, especially dairy products such as yogurts and fermented milks, has experienced rapid growth in Europe. The long-term exploitation of probiotics as health promoters is dependent on several factors, including sound, scientifically proven clinical evidence of health-promoting activity; accurate consumer information; effective marketing strategies; and, above all, a quality product that fulfills consumer expectations.

Follicular development during early pregnancy and the estrous cycle of the sow.

The objective of this study was to monitor and compare follicle populations and follicular development in pregnant and nonpregnant sows from Day 3 to Day 20 after breeding. Twenty-four sows were paired within parity on the day of artificial insemination and were randomly allocated within pair for insemination with either killed (n=12) or live spermatozoa (n=12). All the sows were artificially inseminated with the pooled ejaculate of the same boar. From Day 3 through Day 20 post estrus, ovarian follicles were scanned daily by ultrasonography. Ultrasound images were recorded on videotape and were retrospectively analyzed. Follicles were mapped to identify the existence of follicular waves. The follicles were then classified as small (< 3 mm), medium (3-5 mm), or large (> or =5 mm). Pregnancy diagnosis was performed on Day 21 by ultrasonography. Pregnant sows maintained a constant proportion of the follicle population in the small, medium and large follicle categories. However, in the nonpregnant sows, the proportion of follicles in the various size categories remained constant until Day 15. Thereafter, the proportion of small follicles decreased (P < 0.05) from Day 15 to 20, and the proportions of medium and large follicles increased (P < 0.05). The predictability of pregnancy status on Day 20 based on follicle populations in any of the 3 follicle categories was low. Moreover, there was no evidence of follicular waves during the estrous cycle or early pregnancy. In conclusion, the proportion of small follicles decreased while medium and large follicle increased from Day 15 through Day 20 of the estrous cycle, but not during a similar stage of pregnancy. This latter finding concurs with follicle recruitment from the pool of small follicles for ovulation following PGF2alpha secretion to induce luteolysis, which reduces progesterone concentrations and thereby allows for the stimulation of the pool of small follicles by gonadotropins.

The effects of administration of gonadotrophins and estrogens on prenatal survival in gilts.

In gilts ovulation occurs over a 4 to 8-hour period, with 70% of the ova being shed over a relatively short span of time. These oocytes supposedly give rise to more developed embryos at Days 10 to 12 which advance the uterine environment and reduce survival rates of less developed embryos because of an asynchronous environment. The aim of this experiment was to reduce embryo mortality by influencing the duration and pattern of ovulation. Crossbred gilts (n=98) were bred at their first observed estrus after being exposed to boars at 200 days of age. Estrus detection was carried out daily at 0000, 0800 and 1600 hours. All gilts were artificially inseminated with fresh semen, with a minimum of 2.7 billion spermatozoa, at both 16 and 32 hours after detection of estrus. Gilts were randomly assigned to one of the following treatments at detection of estrus: 1) 500 IU (2 ml) chorionic gonadotrophin (hCG) injected intravenously at the onset of estrus (n=22); 2) 16 microg (4 ml) gonadotrophin releasing hormone (GnRH) injected intravenously at the onset of estrus (n=25); 3) 11.5 microg estrogen added to the semen at the time of AI (n=25); 4) control, untreated gilts (n=26). All gilts were slaughtered at Day 30 of gestation (Day 0=day of detected estrus). The mean (+/-SEM) number of ovulations in pregnant gilts per treatment was 13.0+/-0.52, 12.6+/-0.51, 13.6+/-0.54 and 13.3+/-0.52, while the mean (+/-SEM) number of normal embryos per treatment was 10.3+/-0.67, 10.5+/-0.66, 10.3+/-0.69 and 10.5+/-0.67 for hCG, GnRH, estrogen and control groups, respectively, for an embryonic survival rate of 80+/-4.2%, 83+/-4.1%, 74+/-4.3% and 79+/-4.2% in pregnant gilts. If nonpregnant gilts are included, the embryonic survival rate for treatments 1 to 4 was 76+/-7.0%, 73+/-6.5%, 60+/-6.5%, and 64+/-6.4%, respectively. There was no significant difference between treatments for any of these variables. There was no evidence that administration of hCG, or GnRH at the onset of estrus, or the addition of estrogen to semen improved embryonic survival in gilts by Day 30 in this experiment.

The extent and timing of prenatal loss in gilts.

The potential litter size of gilts that is based on the ovulation rate is much higher than the actual litter size, which depends on the fertilization rate and subsequent prenatal mortality. Prenatal mortality is divided into embryonic mortality (before Day 30) and fetal mortality (after Day 30). Prenatal loss includes both fertilization failure and prenatal mortality. Crossbred gilts (n = 149) were bred at the first observed estrus after being exposed to the boar at 200 days of age. Time of the first insemination after estrus detection was determined by measurement of vaginal conductivity using a Walsmeta meter. A second insemination was administered either 8 or 16 hours later. Artificial insemination with fresh semen (0 to 3 days old) was used throughout the experiment. Gilts were slaughtered on Day 3 (n = 26), Day 10 (n = 42), Day 30 of gestation (n = 45) or they were allowed to farrow (n = 36). Gilts slaughtered on Day 3 were used to estimate the fertilization rate. Gilts slaughtered on Day 10 and Day 30 were used to calculate embryonic mortality, while fetal mortality was calculated from the gilts that farrowed. The mean (+/-SEM) number of corpora lutea (CL) was 13.15+/-0.46, 13.36+/-0.37 and 12.97+/-0.39 for gilts slaughtered at Days 3, 10 and 30, respectively (P>0.05), and the mean (+/-SEM) number of normal embryos recovered was 11.12+/-0.69, 9.46+/-0.55 and 9.33+/-0.58, respectively. Litter size at parturition was 9.10+/-0.54. There was a significant difference between the number of normal embryos on Day 3 and Day 30 (P=0.05) and also between the number of normal embryos at Day 3 and the number of piglets at term. Ninety percent of the ova were recovered at Day 3. The fertilization rate was calculated either 1) assuming that unrecovered ova had a similar fertilization rate as the recovered ova (FRER=94.5+/-2.0%) or 2) assuming that unrecovered ova were unfertilized (FROR=84.5+/-2.5%). It was concluded that FRER was a more accurate estimation of the fertilization rate. Based on this fertilization rate, embryonic mortality between Day 3 and Day 10 was 20.8+/-8.3%, with an additional 12.5+/-7.1% loss between Day 10 and Day 30, when all gilts were included (P = 0.308). Thus the total prenatal loss, including fertilization failure, up to Day 10 was 26.3% and to Day 30 it was 38.8%. Fetal mortality was 2.2%, giving a total prenatal mortality (excluding fertilization failure) of 35.5% and a prenatal loss of 41%. Most of the prenatal loss was due to embryonic mortality. In those gilts that remained pregnant most of the embryonic loss occurred before Day 10 (19.0+/-6.3%; P=0.003). There was no further loss between Day 10 and 30 of pregnancy. There was a significant difference between the loss from Day 3 to Day 10 compared with the loss from Day 10 to Day 30 (P=0.05); therefore, most of the embryonic loss in pregnant gilts occurred before Day 10. Since fetal mortality was 3.2+/-6.3%, most of the prenatal loss was due to embryonic mortality.

Effect of liquid feeding weaned pigs on growth performance to harvest.

Four experiments were undertaken to examine the effect of feeding postweaning diets as dry pelleted feed, fresh liquid feed, acidified liquid feed, and fermented liquid feed on pig performance from weaning (26 d) to harvest. In Exp. 1 (n = 12 replicates) and 2 (n = 10 replicates), the treatments were 1) dry pelleted feed and 2) fresh liquid feed. In Exp. 1, 2 kg of starter diet (16.7 MJ of DE/kg and 1.6% lysine) per pig and 5 kg of transition diet (16.7 MJ of DE/kg and 1.5% lysine) per pig followed by a weaner diet (14.0 MJ of DE/kg and 1.36% lysine) were offered to 27 d after weaning. In Exp. 3 (n = 8 replicates), the treatments were 1) dry pelleted feed, 2) fresh liquid feed, and 3) acidified liquid feed. In Exp. 4 (n = 8 replicates), the treatments were 1) dry pelleted feed, 2) acidified liquid feed, and 3) fermented liquid feed. In Exp. 2, 3, and 4, 3 kg of starter diet (16.1 MJ of DE/kg and 1.74% lysine) per pig and 6 kg of transition diet (15.3 MJ of DE/kg and 1.5% lysine) per pig followed by a weaner diet (14.0 MJ of DE/kg and 1.36% lysine) was offered to 27 d after weaning. All treatments were balanced for boars and gilts and diets were offered for ad libitum consumption. Acidified liquid feed was produced by adding lactic acid to the liquid feed so that its pH was decreased to 4.0. Fermented liquid feed was produced by adding an inoculum of Lactococcus lactis subsp. cremoris 303 (1.3%, vol/wt) to the first mix. In Exp. 1, ADG from weaning to d 27 after weaning was 338 and 286 g/d (SEM = 10; P < 0.01) and DM gain/feed in the same period was 888 and 594 g/kg (SEM = 23.1; P < 0.001) for dry pelleted feed and fresh liquid feed, respectively. In Exp. 2, ADG was 391 and 352 g/d (SEM = 6.4; P < 0.01) and DM gain/feed was 856 and 642 g/kg (SEM = 9.9; P < 0.001) for dry pelleted feed and fresh liquid feed, respectively, during the period from weaning to d 27 after weaning. In Exp. 3, ADG was 408, 416, and 433 g/d (SEM = 12.7; P > 0.05) and DM gain/feed was 865, 755, and 789 g/ kg (SEM = 14.5; P < 0.001) for dry pelleted feed, fresh liquid feed, and acidified liquid feed, respectively. In Exp. 4, ADG was 361, 389, and 347 g/d (SEM = 13.2; P = 0.11) and DM gain/feed was 888, 749, and 733 g/ kg (SEM = 15.8; P < 0.001) for dry pelleted feed, acidified liquid feed, and fermented liquid feed, respectively, during the period from weaning to d 27 after weaning. It is concluded that although feeding acidified liquid feed may have some merit in the first 27 d after weaning, this benefit is lost in the subsequent period. No benefit arose from feeding fresh liquid feed or fermented liquid feed. Growth performance from d 28 after weaning to harvest was not improved by any liquid feed treatment.

Effect of dietary oils and alpha-tocopheryl acetate supplementation on lipid (TBARS) and cholesterol oxidation in cooked pork.

The effect of n-3 fatty acid-enriched diets (in the form of 0.5% linseed oil with either 1.5% sunflower oil or 1.5% olive oil) and alpha-tocopheryl acetate supplementation (200 mg/kg feed) on lipid oxidation (thiobarbituric acid-reactive substances, TBARS) and cholesterol oxide products (COPS) in cooked pork was investigated. Longissimus muscle was studied. Meat from pigs fed 0.5% linseed oil-enriched diets had a higher proportion of n-3 fatty acid than meat from pigs in other dietary groups in neutral (P < 0.0001) and polar lipids (P < 0.0001), and a 20% reduction in the n-6:n-3 ratio was observed. Alpha-tocopheryl acetate supplementation increased (P < 0.05) monounsaturated fatty acids in polar lipids and increased (P = 0.0001) alpha-tocopherol levels in muscle. Alpha-tocopherol concentration in muscle was affected by dietary fat (P < 0.05). Groups receiving diets enriched with sunflower oil had significantly higher alpha-tocopherol levels (P < 0.05) in muscle than those groups receiving olive oil-enriched diets. Numbers of TBARS were significantly (P < 0.05) lower in the group fed supplemental olive oil than in those fed sunflower oil. Dietary linseed oil increased (P < 0.05) lipid oxidation principally at the initial period of storage in cooked pork. Overall, dietary alpha-tocopheryl acetate supplementation significantly increased (P < 0.001) lipid stability and decreased (P < 0.05) total COP production across the dietary groups. Alpha-tocopherol was a more effective antioxidant for decreasing TBARS values in cooked meat when adding sunflower oil to the diets instead of olive oil.

The effects of dietary α-tocopheryl acetate supplementation and modified atmosphere packaging (MAP) on the quality of lamb patties.

The effects of dietary α-tocopheryl acetate supplementation and/or packaging on the quality of lamb patties were investigated. Ewes (n=12) were selected and scanned to assess pregnancy. They were divided into two groups (n=6). The control group was fed a non-supplemented diet of 20 mg α-tocopheryl acetate/kg feed/day for 9 weeks ante-parturition and 3 weeks post-parturition. The lambs were weaned at 3 weeks and fed either the non-supplemented or supplemented diet for 10 weeks prior to slaughter. The M. longissimus dorsi from each carcass from each dietary group was stored at -20°C for 7 months. Patties were formed from supplemented or control minced m. longissimus dorsi and held in either modified atmosphere packs (MAP) under atmospheres of 70:30, 80:20 or 90:10 CO(2):O(2), under vacuum or in overwrapped trays. All packs were held under refrigerated (4°C, 616 lux) display for a period of 10 days. Patties were assessed for oxidative and colour stability on days 0, 2, 4, 6, 8 and 10. With each type of pack, dietary α-tocopheryl acetate supplementation significantly increased oxidative and colour stability compared to control patties. As oxygen concentrations increased in MAP packs, colour stability was enhanced but the rate of lipid oxidation increased. Vacuum packaged patties had significantly (P<0.05) higher Hunter 'a' values, lower proportions of metmyoglobin and lower TBARS numbers than those held under all other forms of packaging. Aerobically packaged patties had lower Hunter 'a' values, higher proportions of metmyoglobin and lower TBARS numbers compared to MAP patties.

Assessment of the antioxidant potential of natural food and plant extracts in fresh and previously frozen pork patties.

Antioxidant activities of aloe vera, fenugreek, ginseng, mustard, rosemary, sage, soya protein, tea catechins and whey protein concentrate (35% protein) were evaluated in pork patties prepared from both fresh and previously frozen (-20°C) pork. Chemical analysis showed test ingredients to be more effective in reducing lipid oxidation in patties made from previously frozen pork. Tea catechins, rosemary and sage were identified as being the most effective antioxidants with potency decreasing in the following order: tea catechins>rosemary>sage. Optimum addition rates of these ingredients suggested levels of 0.25, 0.10, 0.05% for tea catechins, rosemary and sage, respectively. Soya protein (0.10%) increased meat redness in fresh pork patties producing significantly (P<0.05) higher Hunter 'a' values over the controls on days 0, 3 and 6. However, fenugreek (0.01%) was more effective in increasing Hunter 'a' values in patties manufactured from previously frozen pork. No significant (P>0.05) differences in Hunter 'L' and 'b' values were found between test and control samples on storage. The pH values of tea catechins, sage and soya protein fluctuated over time. Fresh pork patties with mustard and ginseng caused an initial decrease followed by a subsequent increase in pH values. Fenugreek caused an initial increase in pH values followed by a decrease from day 3 onwards.

The effect of dietary vitamin E supplementation on the quality of fresh and frozen lamb meat.

The effect of dietary α-tocopheryl acetate supplementation on the uptake of α-tocopherol in ewe plasma, lamb plasma, milk, organs and muscles was investigated. The oxidative stability and colour in fresh M. longissimus dorsi and frozen M. longissimus dorsi, M. psoas major and M. gluteus medius were also investigated. Ewes (n = 12) were selected and scanned to assess pregnancy. They were divided into two groups (n = 6). The control group was fed a diet containing 20 mg α-tocopheryl acetate/kg feed/day and the supplemented group fed a diet containing 1000 mg α-tocopheryl acetate/kg feed/day, for 9 weeks ante-parturition and 3 weeks post-parturition. The lambs were weaned at 3 weeks and fed supplemented or basal feed for 10 weeks before slaughter. Plasma α-tocopherol increased significantly (p < 0.01) in ewes in the 9 weeks ante-parturition, and lamb plasma taken just before slaughter was significantly (p < 0.01) higher for the supplemented group than the basal group, following 13 weeks of supplementation. Milk α-tocopherol levels were significantly (p < 0.01) higher from ewes fed the supplemented diet at parturition and for the three weeks of supplementation post-parturition (p < 0.05). Supplementation increased the α-tocopherol levels in all tissues sampled. The α-tocopherol concentrations in M. longissimus dorsi and M. psoas major were also determined after frozen storage at -20 °C for 34 weeks. Frozen storage resulted in a significant (p < 0.01) reduction in mean α-tocopherol levels for M. longissimus dorsi but not M. psoas major. Dietary supplementation with α-tocopheryl acetate significantly (p < 0.05) increased the oxidative stability of lamb muscle. Surface colour (Hunter L, a, b) was found to be negatively correlated with metmyoglobin content. Supplementation reduced surface discolouration in refrigerated display under fluorescent light over a 6-7 day storage period. The effect was more pronounced in frozen displayed muscles than in freshly displayed samples.

The distribution of dietary vitamin E in the muscles of the porcine carcass.

The objectives of this study were to determine the effect of dietary vitamin E supplementation on tissue α-tocopherol levels in muscles in the porcine carcass. Pigs (n = 9), were selected at random and divided into three groups (n = 3) and fed diets containing 0 (basal), 20, 160 mg dl-α-tocopheryl acetate/kg feed for a period of 130 days prior to slaughter. After slaughter carcasses were split centrally and chilled at 4 °C × 24 h. Muscles (n = 37) were identified and removed from the left side of each animal for each dietary group and stored at -20 °C until required. The mean α-tocopherol levels in pork muscle tissue were significantly (p < 0.05) higher in the high-supplemented group (160 mg α-tocopheryl acetate/kg of feed) compared with the low-supplemented (20 mg/kg of feed) and basal groups (unsupplemented). In the supplemented samples, the muscles of the thoracic limb (4.8-9.9 mg α-tocopherol/kg of tissue) and neck and thorax (3.7-9.2 mg/kg) contained the greatest levels of α-tocopherol compared the muscles of the pelvic limb (4-5.6 mg/kg) and back (2.5-3.5 mg/kg).

Influence of dietary fat and α-tocopherol supplementation on lipid oxidation in pork.

Sixty-four pigs, approximately 3 weeks old, were fed diets containing 3% beef tallow or 3% soya oil with either a basal (10-50 mg/kg diet) or supplemented (200 mg/kg diet) level of α-tocopheral acetate. In pigs fed the soya oil diet the neutral and polar lipid fractions of muscle tissue and the total lipid fraction of adipose tissue had significantly (P < 0·05) higher C18:2/C18:1 ratios when compared to pigs fed the tallow diet. Muscle from pigs fed the soya oil diet was significantly more susceptible (P < 0·05) to lipid oxidation than muscle from pigs fed the tallow diet. In pigs receiving the α-tocopherol supplemented diet, α-tocopherol levels were approximately 3·3, 2·8 and 2-times higher in plasma, muscle and adipose tissue, respectively, when compared to pigs fed the basal level of α-tocopherol acetate. α-Tocopherol supplementation significantly increased (P < 0·05) the oxidative stability of muscle from pigs fed both the tallow and soya oil diets.

Uptake of α-tocopherol in porcine plasma and tissues.

The effect of feeding α-tocopheryl acetate to pigs on the rate and extent of uptake of α-tocopherol in various tissues was investigated. The rate of iron ascorbate-induced lipid peroxidation was also studied. One hundred and eight Landrace × Large White pigs were assigned at random to one of the following barley-based diets: 20 mg α-tocopheryl acetate/kg feed for up to 126 days; 20 mg/kg feed to day 91, followed by 200 mg/kg feed to day 126, or 200 mg/kg feed for up to 126 days: Pigs from each group were slaughtered at specified intervals. For pigs fed the diet supplemented with 200 mg α-tocopheryl acetate/kg feed, α-tocopherol levels increased with increasing supplementation time up to day 126 in all tissues studied. The highest levels of α-tocopherol were observed in kidney fat and subcutaneous fat (inner layer) followed by subcutaneous fat (outer layer), liver, lung, heart, kidney, with muscle and brain containing approximately the same level. The α-tocopherol concentrations in all tissues examined, from pigs fed 200 mg α-tocopheryl acetate/kg feed from weaning to day 126 were greater than those fed the supplemented diet for 35 days. Iron-induced lipid peroxidation was reduced by dietary α-tocopheryl acetate supplementation, and muscle samples from pigs supplemented for 126 days were significantly (p < 0.05) less susceptible to peroxidation compared to muscle from pigs fed the same supplemented diet for 35 days.

Influence of the time of year on the incidence of PSE and DFD in Irish pigmeat.

The conditions of PSE (pale, soft, exudative) and DFD (dark, firm, and dry) are significant causes for downgrading of pigmeat resulting in financial loss to the slaughter plant. The objective of this study was to document the variation in quality of pigmeat from one slaughter plant over a 15-month period, based on colour, appearance and pH. During 4 days of most weeks, 30 pigs were randomly selected from the slaughter line, resulting in a total number of 4560 pigs. Muscle pH between the third and fourth rib was measured 45 min, 90 min and 24 h after slaughter. Using a Minolta colorimeter (Hunter L, a, b scale), colour of the longissimus dorsi muscle was measured 24 h after slaughter. Muscle colour was also visually scored on a scale of 1-6. Carcass pH at 24 h post-mortem varied significantly with month of slaughter (P<0.04) as did colour (Hunter L, P<0.001; Hunter a, P<0.001; Hunter b, P<0.001). It was concluded that meat quality as measured by 24 h pH and colour was poorest during the months of November and December. While this may be at least partly related to weather, it is probable that the increased slaughtering rates at this time and variable resting period before slaughter had the biggest impact.

Effects of PSE on the quality of cooked hams.

Meat quality comparisons were carried out on hams produced from pork legs showing evidence of PSE and normal pork legs. Quality measurements included drip loss, sliceability, cooking loss, TBARS analysis and colour evaluation (Hunter L, a, b). A total of 40 pork legs were selected from a commercial slaughtering plant, 20 from carcasses showing PSE and 20 from normal carcasses based on L, a, b, and pH values. Carcass pH taken between the third/fourth rib was measured 45 min, 90 min, and 24 h after slaughter. Using a Minolta colorimeter (Hunter L, a, b,), colour of the Longissimus dorsi muscle was measured 24 h after slaughter. PSE had an adverse effect on cooked hams in comparison to normal cooked hams with respect to driploss (P<0.01), cooking loss (P<0.01), sliceability (P<0.01), colour (P<0.05) and lipid oxidation (P<0.05). Cooked hams manufactured from severe PSE pork in this study had an estimated financial loss of 50% (IRL£4.90) in comparison to those manufactured from normal pork (IRL£9.80).

Reduced nitrite levels and dietary α-tocopheryl acetate supplementation: effects on the colour and oxidative stability of cooked hams.

The objective of the present study was to determine the effects of dietary vitamin E supplementation and reduced nitrite levels on the colour stability of cooked hams. Large white × Landrace pigs (male n=6, female n=6) were each subdivided into two groups (n=3) and fed an α-tocopheryl acetate supplemented diet (1000 mg/kg feed) and a basal diet (10 mg/kg feed) for a period of 10 weeks. M. semitendinosus were removed from each pig, divided into light and dark pigmented fractions, vacuum packed and stored at 4°C for 24 h. Muscles were cured with input nitrite levels of 25 and 100 mg/kg meat and were tumbled and massaged for 17 h. Samples were cooked, sliced and overwrapped in a high oxygen permeable film for a storage period of 10 days. Surface colour of hams was measured and expressed as Hunter 'a' values. Concentrations of α-tocopherol were significantly (P<0.001) greater in supplemented muscles compared to basal muscles for both male and female pigs. Hams manufactured from male and female supplemented pigs resulted in significantly (P<0.001) higher Hunter 'a' values than hams manufactured from male and female pigs receiving the basal diet. Muscles cured with 100 mg nitrite/kg meat formed products with significantly (P<0.001) higher 'a' values than those cured with the lower (25 mg/kg meat) nitrite level. Hams manufactured from supplemented muscles, treated with 25 mg nitrite/kg meat showed significantly (P<0.05) higher Hunter 'a' values than hams manufactured from basal muscles, treated with 100 mg nitrite/kg meat. Hams manufactured from female porcine muscles had significantly (P<0.001) higher 'a' values than hams from male muscles during the 10 days of simulated retail display. No such gender differences were observed for TBARS values.

Evaluation of the antioxidant potential of natural food/plant extracts as compared with synthetic antioxidants and vitamin E in raw and cooked pork patties.

Antioxidant potential for previously identified optimum levels of aloe vera (AV), fenugreek (FGK), ginseng (G), mustard (M), rosemary (R), sage (S), soya protein (SPI), tea catechins (TC) and whey protein concentrate (WPC) were evaluated in raw and cooked patties manufactured from frozen pork. The optimum levels determined were: AV (0.25%), FGK (0.01%), G (0.25%), M (0.10%), R (0.10%), S (0.05%), SPI (0.10%), TC (0.25%) and WPC (4%). Test ingredients were evaluated against synthetic antioxidants butylated hydroxyanisole/butylated hydroxytoluene (BHA/BHT) (0.01%) and a supplemented meat containing natural antioxidant, α-tocopherol (1000 mg α-tocopheryl acetate/kg feed). Ranking the decreasing antioxidant effectiveness of added ingredients in raw patties on day 9 showed that: Control>G>SPI>FGK>AV>M>WPC>S>α-tocopherol>R>TC>BHA/BHT. Cooking resulted in a four-fold increase in TBARS values over raw patties with TC being the most effective antioxidant having significantly (P<0.001) lower TBARS values than the cooked control on days 3, 6 and 9. Ranking of decreasing antioxidant effectiveness of added ingredients showed that: M>SPI>G>FGK>α-tocopherol>AV>control>S>BHA/BHT>R>WPC>TC. BHA/BHT had the most beneficial effect on cooked meat redness with Hunter 'a' values being significantly (P<0.05) higher than the control on days 3, 6 and 9. Ranking of Hunter 'a' values for added test ingredients showed that FGK>WPC>control>R>BHA/BHT>α-tocopherol>TC>AV>SPI>M>G>S on day 9. Hunter 'L' and 'b' values showed no significant trend over the storage period in either raw or cooked patties. The pH values of both raw and cooked pork control patties and products containing added test antioxidants were variable and while a number of trends were observed, no significant differences were recorded between samples.

Effect of dietary Vitamin E on the stability of raw and cooked pork.

Experiments were designed to investigate the effects of dietary α-tocopherol supplementation for 2 weeks prior to slaughter on plasma and muscle α-tocopherol levels and on the oxidative stability of raw and cooked pig muscle during refrigerated storage at 4°C. Plasma and muscle α-tocopherol levels of the pigs on the α-tocopherol supplemented diet (200 mg α-tocopherol acetate/kg feed) were ∼2·5-fold higher than those of the pigs on the control diet (30 mg α-tocopherol acetate/kg feed). Dietary supplementation with α-tocopherol significantly (p < 0·01) improved the oxidative stability of both raw and cooked muscle after storage at 4°C for up to 8 days. α-Tocopherol stabilized the membrane-bound lipids against metmyoglobin/H(2)O(2)-initiated oxidation and also significantly (p < 0·05) improved the oxidative stability of rendered fat.

Salmonella serotypes present on a sample of Irish pig farms.

A survey of the prevalence of Salmonella species infection was conducted on 59 Irish farrow-to-finish pig herds. Faecal samples were collected from the pens of first-stage weaners (growing pigs approximately three to 10 weeks of age), second-stage weaners (approximately 10 to 17 weeks of age) and fatteners, and from the dry sow and farrowing sow houses. The prevalence of infection was estimated to within 5 per cent with a 95 per cent confidence interval. Thirty of the 59 herds were infected, 12 with Salmonella Typhimurium only, eight with Salmonella Derby only and seven with both S Typhimurium and S Derby; serotypes London, Livingstone and Infantis were each isolated from a single herd. Farms in Ireland are assigned to one of three infection categories on the basis of the antibody levels in samples of meat juice taken at slaughter. When a herd was classified as either positive or negative on the basis of the isolation of Salmonella from at least one faecal sample there was no association between the herd's category as determined by meat juice serology and the probability of the isolation of Salmonella from the faecal samples. However, there were differences in prevalence between pigs at different stages of production in herds of different categories. Farrowing sow houses in moderately infected (category 2) herds had significantly lower infection rates (P < or = 0.05) than other herd categories and other stages of production. Pigs from first-stage weaner pens in slightly infected (category 1) herds were more likely to be infected with Salmonella than pigs at any other stage of production or category of herd.