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Commercial crossbred barrows and gilts (n = 340) were used to study the effects of different dietary inclusions of ractopamine hydrochloride (RAC) on quality of LM and semimembranosus muscle (SM). Pigs were blocked by BW (107.3 ± 0.76 kg) and allotted to gender-specific pens (10 to 12 pigs/pen), and within blocks, pens of barrows or gilts (10 pens/treatment) were randomly assigned to 1 of 3 dietary RAC inclusions (0, 5, or 10 mg/kg) fed during the last 28 d before slaughter. Initial (45-min) and ultimate (24-h) pH and temperature were measured in LM and SM. Visual and instrumental [lightness (L*), redness (a*), and yellowness (b*) values] color as well as drip loss percentages were measured in both muscles after the 24-h chilling period at 1 to 4 °C. The LM was also evaluated for marbling, and samples of the LM were used to measure intramuscular fat (IMF) content, cooking losses, and Warner-Bratzler shear force (WBSF). Pork quality characteristics of the LM (P ≥ 0.227) and SM (P ≥ 0.082) did not differ between barrows and gilts. Furthermore, neither pH nor temperature of the LM (P ≥ 0.164) or SM (P ≥ 0.284) was affected by feeding pigs RAC. The LM from pigs fed 10 mg/kg of RAC received lesser (P = 0.032) subjective color scores than LM from pigs fed 0 and 5 mg/kg of RAC, and LM from pigs fed 10 mg/kg of RAC was less (P = 0.037) red than LM from pigs fed 0 mg/kg of RAC. In addition, SM from pigs fed 10 mg/kg of RAC had lesser (P ≤ 0.015) a* and b* values than pork from control-fed pigs; however, L* values for LM and SM were not (P ≥ 0.081) affected by dietary RAC. Drip loss percentages of the LM were similar (P = 0.815) among RAC treatments, but the SM from RAC-fed pigs had smaller (P = 0.020) drip loss percentages than SM from pigs fed 0 mg/kg of RAC. Marbling scores and IMF content of the LM did not (P ≥ 0.133) differ among RAC treatments; however, WBSF values were greater (P = 0.005) for LM chops from pigs fed 10 mg/kg than chops from pigs fed 0 and 5 mg/kg of RAC. Even though feeding barrows and gilts 10 mg/kg of dietary RAC reduced (P = 0.050) cooking losses of LM chops compared with feeding 5 mg/kg of RAC, including 10 mg/kg of RAC in the diet of finishing pigs reduced pork tenderness. Therefore, results from this study support the recommendation that including 5 mg/kg of RAC in finishing diets should improve live pig performance without detrimental effects on fresh pork quality and cooked pork palatability.

Foram incubados 61.920 ovos, provenientes de uma única linhagem comercial de matrizes de frangos de corte. Foi avaliado o efeito da utilização de diferentes temperaturas de incubação (T), medidas pelo termômetro de bulbo úmido em graus Celsius (ºC), em ovos de matrizes categorizados por peso (P), com idades (I) distintas, sobre o percentual de nascidos totais (eclosão), a eclodibilidade, o percentual da perda de peso dos ovos e a mortalidade embrionária. Utilizou-se um delineamento inteiramente casualizado num esquema fatorial 3 x 4 x 5, representando, respectivamente, três temperaturas de incubação (28,6, 29,6 e 30,6ºC), quatro idades em semanas (34, 39, 53 e 63) e cinco categorias de pesos de ovos, com médias de peso (g) de 60,0; 65,1; 66,6; 69,0; e 73,2. A mortalidade embrionária total (Metot) foi menor na temperatura de 28,6ºC . Na idade de 39 semanas, obteve-se a menor Metot e para categorias de peso os ME apresentaram as menores médias. Houve efeito significativo dos fatores idade e categorias de peso e das interações entre I x P, T x I e T x I x P no peso médio dos ovos (Povo). Para o percentual da perda de peso dos ovos (Pppeso) até a transferência, verificou-se efeito significativo para temperatura, idade e categorias de peso de ovos. Os percentuais de eclosão e eclodibilidade (Eclod) foram otimizados com 10,3% de perda do peso durante a incubação a 28,6ºC.

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