H. Rémignon

Effect of feed rationing during post-weaning growth on meat quality, muscle energy metabolism and fibre properties of Biceps femoris muscle in the rabbit.

During the weaning period (5 weeks of age), 50 hybrid rabbits were divided at random into five groups (or blocks). Animals from the block 1 were immediately slaughtered at this age and used as initial reference. The remaining rabbits were placed in individual cages and fed the same amount of food until slaughter, but differently rationed. From 5 to 8 weeks of age, the rabbits coming from blocks 2 and 4, and from blocks 3 and 5 received 70% and 90% of the ad libitum ration, respectively. Animals of blocks 2 and 3 were slaughtered at 8 weeks of age. Between 8 and 11 weeks of age, animals from blocks 4 and 5 were fed, respectively, 90% and 70% of the ad libitum ration, prior to sacrifice. At slaughter the Biceps femoris (BF) muscles were immediately removed from each rabbit and the ultimate pH (pHu) and meat colour L*a*b* parameters were measured. Thereafter, one BF was used for aldolase and isocitrate dehydrogenase (ICDH) activity determinations, while the other BF muscle was used for fibre distribution (% of βR, αR and αW) and morphometric trait measurements. As expected, at 8 weeks of age, rabbits given for 3 weeks the strictest feed rationing (70% of the ad libitum ration) were lighter than rabbits fed the lowest feed rationing (90% of the ad libitum ration). At 11 weeks of age, rabbits given the 70% ration initially and then switched to 90% ration showed significantly higher body weights than rabbits fed the alternative diet (90% ration initially and then switched to 70% ration), and the best feed conversion ratio. Fibre type distribution, fibre cross-sectional area and compactness, colour and metabolic characteristics varied according to slaughter age. The effects of feeding treatment were low.

Proteomic profile evolution during steatosis development in ducks

We investigated a protein profile evolution during steatosis in ducks using 2-dimensional electrophoresis gels to better understand the mechanisms underlying liver steatosis at the level of hepatic proteins in waterfowl. Two-dimensional electrophoresis gels were performed in the liver at different stages of steatosis in the duck. Mule ducks were slaughtered after 0, 14, or 23 meals of overfeeding, according to commercial conditions. Thirty-one proteic spots were differentially expressed between 3 or 2 durations of overfeeding: 3 spots were differentially expressed between the 3 times and 28 spots were differentially expressed between 2 times. The identified proteins (14) could be regrouped into 5 categories: enzymes, translation factors, proteins involved in cell structure, proteins with antioxidant properties, and proteins that can link calcium. This study opens new research areas in the understanding of steatosis in waterfowl, such as cell structure and oxidative stress.

Effect of "wooden breast" appearance on poultry meat quality, histological traits, and lesions characterization

Dalle Zotte A., Tasoniero G., Puolanne E., Remignon H., Cecchinato M., Catelli E., Cullere M. (2017): Effect of “Wooden Breast” appearance on poultry meat quality, histological traits, and lesions characterization. Czech J. Anim. Sci., 62, 51–57. The purposes of the study were to investigate the effects of Wooden Breast (WB) myodegeneration on poultry meat quality and to give a contribution in typing lesions morphology. At a poultry meat cutting facility, 474 carcasses of a high-breast-yield hybrid chickens were inspected for WB condition, and 30 normal (N) and 30 affected (WB) breast fillets (Pectoralis major) were randomly selected. The WB condition represented 53.2% of the examined carcasses. Weight, cross sectional area (CSA), pH, L*, a*, b* colour values, water-holding capacity, and Warner-Bratzler shear force were determined. Samples were also visually and histologically evaluated. Affected samples were heavier, thicker, paler (P < 0.001), and characterized by palpatory hardness and lower water holding capacity (P < 0.05). Macroscopically, abnormalities were primarily localized in the cranial portion of the fillet and defined by the presence of bulges, petechiae, fluid and clear exudate, and higher pH. Microscopically, the WB condition was characterized by muscle fibres with greater CSA (P < 0.001) and higher giant fibres prevalence (P < 0.01). Data suggest a relationship between breast weight and WB condition.

Proteolytic activity alterations resulting from force-feeding in Muscovy and Pekin ducks

We investigated liver protease activity in force-fed and non-force-fed ducks using zymography gels to better understand mechanisms underlying liver steatosis in palmipeds. Male Muscovy and Pekin ducks were slaughtered before and after a short period (13 d) while they were conventionally fed or force fed. The force-fed regimen contained a high level of carbohydrates and was delivered in large doses. Main hepatic proteases (matrix metalloprotease-2, calpains, and cathepsins) were extracted from raw liver and specifically activated within electrophoretic gels. Both force-fed Muscovy and Pekin ducks presented higher liver weights and BW associated with lower matrix metalloprotease-2 and m-calpain hepatic activities. On the other hand, hepatic cathepsin activity was not affected by force feeding. It was concluded that Muscovy and Pekin duck hepatic proteases are affected similarly by the force feeding. Thus, this cannot explain differences observed between Muscovy and Pekin ducks regarding their ability to develop hepatic steatosis generally reported in literature.

Apoptosis during the development of the hepatic steatosis in force-fed ducks and cooking yield implications

ABSTRACT Mule ducks were force‐fed for 12 d to determine whether or not signs of apoptosis could occur during the development of the hepatic steatosis induced by the huge quantities of corn ingested twice daily by the birds. Presence of apoptosis in hepatocytes was assessed through the measurements of increased activities of capsase‐3 +‐7, ‐8, and ‐9. From d 0 of the force‐feeding period until d 8, activities of the different caspases remained at a low level. On the contrary, at d 10 and d 12, activities of all measured caspases dramatically increased, indicating that apoptosis occurred at this stage, which corresponds to the time of accumulation of large quantities of lipids in the hepatic cells. The melting level of the liver issued from force‐feeding (“foie gras”) during cooking is a point of interest for processors because it could degrade the quality of this delicate dish. In this study, we used the levels of caspases activities to improve the predictability of foie gras cooking, in addition to other parameters usually used, such as its weight or lipid content. From this improvement, we suggest that part of the variability of melting during cooking of fatty livers could reside in more or less intense activity of hepatic proteases.