Effect of parity and stage of lactation on milk yield, composition and quality of organic sheep milk

Abstract

Effect of parity (PA), stage of lactation (SL) and interaction of PA x SL on daily milk yield (DMY), composition (contents of total solids, fat, total protein and lactose) and quality (somatic cell and bacteria counts) of organic sheep milk were evaluated using 20 ewes of East Friesian which were reared on an organic farm in Habří. Ewes were on the 2nd (n = 10) and 3rd (n = 10) lactation. During the experiment ewes were reared on permanent pasture. The milk records and samplings were carried out on average 75th, 132th and 190th day of lactation. All parameters were determined by standard methods. The PA had a significant effect only on somatic cell count (SCC). On the other hand, SL had a significant effect on daily milk yield (DMY), contents of total solids (TS), total protein (TP) and lactose (L). The SL also had a significant effect on total bacteria count (TBC), psychrotrophic bacteria count (PBC), total coliform count (TCC) and SCC. The interaction of the PA x SL had a significant effect on DMY, TS and TP contents and PBC. Positive and significant correlations were found among the SL and contents of TS and TP. Significant and positive correlation was observed between the PA and SCC, but on the other hand, significant and negative correlation was found between the SL and SCC.