Poultry by-products are not often processed into high-value products. Rather than being transformed into meal for animal feed, a large quantity of chicken skin could be used to produce collagen, which is valued for its unique functional properties. The purpose of this research project was to extract and characterize collagen from chicken skin. Skins were first ground and then were heated to 40 or 60 degrees C to extract the fat. After mechanical separation, the collagen contained in the resulting solid phase was extracted with pepsin or ethylene diamine. Types I and III collagen were then isolated and characterized by SDS PAGE, antigen labeling, determination of tyrosine residues, and transmission electron microscopy. The total collagen content of the skin was recovered from the solid phase following heat treatment at 40 degrees C. Extraction yields varied with the solubilization process: 38.9% of the collagen content in the solid phase was extracted with pepsin and 25.1% with ethylene diamine. Ratios of type I to type III collagen fractionated using NaCl were 74.4:19.8% with pepsin and 62.4:31.7% with ethylene diamine. Characterization tests further revealed the presence of telopeptides solely on ethylene diamine-solubilized collagen. Chicken skin thus appears to be a good alternative source of high-quality collagen.
The goal of this study was to evaluate the impact of winter rearing environment on the growth performance and meat quality of heavy lambs. Half of sixty-four Dorset lambs (32 males and 32 females) were raised in each of two different environments: warm and cold with average temperature of 10.9 ± 0.7 °C and -2.0 ± 5.2 °C, respectively. The lambs were slaughtered at live weights of 41-45 kg for females and 46-50 kg for males. Cold environment had no adverse effect on either growth performance or carcass quality. The rate of longissimus dorsi muscle deposition (P = 0.049) and its depth at slaughter (P = 0.027) were rather greater in lambs reared in the cold environment and a higher proportion of oxido-glycolytic fibres (P = 0.047) was also observed in this muscle. Rearing environment had only a minor effect on the organoleptic qualities, with the cold environment promoting juiciness of the meat (P = 0.043). Therefore, cold environment rearing such as used in this study represents an economic advantage for lamb producers by reducing the costs associated with the construction of insulated barns, while maintaining growth performance, as well as carcass and meat quality. Key words: Lamb, rearing environment, temperature, growth, carcass, meat quality
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