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One hundred twenty-eight 64-kg crossbred barrows and gilts were administered either 0 or 20 ppm of Ractopamine (RAC) in a pelleted corn-soybean meal diet that contained either 17.5 or 19.6% CP. Carcass quality was evaluated after slaughter at 100 kg. Dietary protein levels produced few significant effects; therefore, data were pooled for analysis. Pigs fed RAC exhibited improvement in feed efficiency (P < .01), ADG (P < .01), and number of days to slaughter (P < .01). Pigs fed RAC had 1.8 mm less fat (P < .05) and 3.4 mm more lean (P < .01) at the grading probe site. Gilts had 4.9 mm less fat than barrows at the probe site (P < .01) and also yielded an estimated 4.1% more lean (P < .01). Trimmed loins and bellies of animals fed 20 ppm of RAC were 230 g heavier (P < .05) than those of animals fed the control diet. Trimmed loins from gilts were 260 g heavier (P < .05), whereas barrows produced bellies that were 490 g heavier (P < .05) than those of gilts. The yield of processed ham was greater from both pigs fed RAC (P < .01) and barrows (P < .05). Loins of pigs fed RAC had lower cooking loss (P < .05), greater Warner-Bratzler shear value (P < .05), and higher fragmentation index value (P < .01). Although effects of sex were similar to or greater than the effects of 20 ppm of RAC, these effects were additive.

. 1999. The effects of feeding conjugated linoleic acid on subsequent pork quality. Can. J. Anim. Sci. 79: 45-51. Feeding conjugated linoleic acid (CLA) has recently been shown to repartition fat to lean in pigs. The present study was undertaken to determine if feeding CLA affects pork quality. Pigs were fed a cereal-based diet containing either 2% CLA or 2% sunflower oil. Fifty-four pigs (27 gilts and 27 barrows) were fed per diet, and diets were fed from 61.5 to 106 kg liveweight. Diet did not affect postmortem longissimus thoracis (LT) glycogen utilization, lactate accumulation, or pH decline. Conjugated linoleic acid fed pigs had slightly higher LT temperatures at 3 h postmortem (+1.15°C; P < 0.05), but subsequent LT shear force, drip loss and soluble protein levels were unaffected. Diet did not affect subjective LT scores for structure or color, but objective color measurements indicated LT from CLA-fed pigs had slightly higher chroma (color saturation) values (+0.84; P < 0.05). Longissimus thoracis from CLA-fed pigs also had increased subjective marbling scores (P < 0.01) and increased petroleum-ether-extractable intramuscular fat (+22%; P < 0.01). Diet did not affect any measured palatability characteristic (initial and overall tenderness, juiciness, flavor desirability, flavor intensity, connective tissue amount, overall palatability; P > 0.05). Feeding 2% dietary CLA to pigs, therefore, shows some potential for improving pork composition by increasing intramuscular fat, while having no detrimental effect on pork quality. On a récemment constaté que l'administration de l'acide linoléique conjugué (ALC) favorise la répartition lipido-protidique chez les porcs. Nos travaux avaient pour objet de vérifier si ALC influe sur la qualité de la viande. Les porcs utilisés recevaient une ration à base de céréales contenant 2 % d'ALC ou 2 % d'huile de tournesol. Cinquatre-quatre porcs, soit 27 cochettes et 27 castrats, étaient affectés à chaque régime, l'expérience durant jusqu'à ce qu'ils atteignent le poids vif de 61,5 à 106 kg. Le régime n'avait pas d'effet sur l'utilisation du glycogène, sur l'accumulation des lactates ou sur la baisse du pH post-mortem dans le longissimus thoracis (LT). Les sujets recevant ALC montraient une température du LT légèrement plus haute 3 h après l'abattage, soit 1,15 °C de plus (P < 0,05) mais, par la suite, la force de cisaillement, les pertes d'égouttage et les concentrations de protéines solubles ne différaient pas de celles obtenues dans le régime à l'huile de tournesol. Le régime n'avait pas non plus d'effet sur les notations subjectives du LT quant à la structure ou à la coloration, mais les mesures colorimétriques objectives révélaient un indice de saturation légèrement plus élevé dans le LT des porcs recevant l'ALC, soit 0,84 de plus (P < 0,05). En outre, chez ces derniers, les notations subjectives du persillé de la viande étaient plus élevées (P < 0,01), de même que les quantités de gras intramusculaire extractible dans l'éther de pét-role, soit 22 % de plus (P < 0,01). Au...

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The oxygen (O2) absorption kinetics of six commercial O2 scavengers were studied. The scavengers were placed in bags which were filled with 240 mL of air, 4.5 L N2 + 15 mL of air, or 3.5 L CO2 + 9 mL of air. The O2 concentration in each bag was measured at hourly intervals for 8 h. The effects of variability among individual scavengers, initial O2 concentrations of 20% or 500 ppm (0.05%), temperatures of 25, 12, 2 or −1.5 °C, and scavenger capacity on the O2 absorption rate were determined. In addition, the effect of placing scavengers within over‐wrapped trays within bags, was examined. Rates of O2 absorption varied by factors of up to 2 between individual O2 scavengers of the same type, but rates of absorption by groups of four scavengers of the same type were similar. Low temperatures gave longer O2 half‐life when compared with those at higher temperatures, e.g. O2 half‐lives of 7.1 and 1.0 h at −1.5 and 25 °C, respectively, were obtained for one scavenger type. Shorter O2 half‐lives were obtained in air than in N2 atmospheres at the same temperature, e.g. O2 half‐lives of 1.0 and 3.3 h in air and N2 at 25 °C, respectively, were obtained for one scavenger type. The O2 absorption reactions were of first order for both high and low initial O2 concentrations. However, O2 concentration was the primary limiting factor for O2 absorption in atmospheres having O2 concentration of 500 ppm because of the dominance of diffusion. Scavengers, when placed within over‐wrapped trays within bags had up to 12 times longer O2 half‐lives, indicating that the O2 permeable film acts as an O2 barrier when pack atmosphere has low O2 concentrations. To obtain consistent and reproducible results, it is recommended that multiple scavengers be used in a packaging system. The appropriate number should be based on scavenger type, desired O2 absorption rate, storage temperature, and pack atmosphere (air/N2/CO2).

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