Chemical composition and biological protein value of milk of Tsigai sheep and their F2 cross-breeds of Chios
2014
Gerchev, G. (Research Institute of Mountain Stockbreeding and Agriculture, Troyan (Bulgaria)) | Iliev, T. (Trakia University, Stara Zagora (Bulgaria)) | Slavkova, S. (Research Institute of Mountain Stockbreeding and Agriculture, Troyan (Bulgaria)) | Mihaylova, G. (Trakia University, Stara Zagora (Bulgaria))
The composition of milk was studied from purebred Tsigai sheep and F2 cross-breeds with Chios breed from 4th to 6th month of lactation, raised on a mountain pasture. The chemical analysis samples were taken from each sheep in the period of April-June. The content of fat, protein and amino acids was determined in individual samples and total sample formed by the milk yield from all animals, proportional to the daily milk yield from each individual. There is a tendency for higher milk yield and content of total protein and casein in milk of F2 cross-breeds of Chios in comparison with Tsigai sheep. Milk sheep from F2 cross- breeds of Chios had higher content of Lysine, as well as glutamic acid, methionine and leucine, in comparison to that form Tsigai sheep, respectively: 0.458±0.011. 1.389±0.040. 0.084±0.005 and 0.572±0.013. The milk chemical index in both groups of sheep was comparatively low and it constituted respectively 38.3% in Tsigai sheep and 35.4% in F2 cross-breeds, as a result of low concentrations of methionine and cysteine in milk. Biological value of milk obtained from Tsigai breed sheep and F2 milk cross-breeds of Chios had close values - respectively 92.01 and 91.87%. Results showed that the sward composition and the vegetation stage had an influence over the essential amino acids content in purebred Tsigai sheep and their cross-breeds with Chios breed
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