Changes of basic composition and properties of sheep milk during lactation
1990
Jelinek, P. | Gajdusek, S. | Helanova, I. | Hlusek, J. (Vysoka Skola Zemedelska, Brno (CSFR)) | Illek, J.
Changes in milk composition and properties were studied in 12 ewes of Tsigai breed and in 10 crossbred ewes with a 62.5-percent gene proportion of the Tsigai breed and a 37.5-percent gene proportion of the East-Fresian breed from the 7th day after parturition till the end of the first lactation. Dry matter content in milk lowered until the 34th day of lactation, then the trend was rising. Similar changes were observed in the contents of fat, protein, casein and ash. The quantity of lactose increased till the 34th day and then there occured a mild lowering of this component in milk. Urea concentration fluctuated significantly and when the ewes transfered to full-time pasture, the level of this metabolite showed a highly significant temporary increase. Titration acidity of milk exhibited a similar fluctuation in dependence on the changes of protein and ash contents. The number of somatic cells showed a higher variability and a temporary increase at the start of the pasture. The activity of acid phosphatase was highest at the begining of lactation; activity of alkaline phosphatase increased regularly during the whole study. Vitamin A and E contents increased at a higher variability as the lactation progressed. The time of rennet clotting of the milk was the longest at the begining of lactation and later it fluctuated independently of the lactation phase. Differences between the groups of ewes in the studied components in milk were not significant during evaluation for the whole lactation. Sporadic significant differences were recorded only in some parts of the lactation period.
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