Relationship of litter size with milk yield, udder morphology and udder health of East Friesian sheep

The aim of this study was to determine relationship between litter size and milk yield, udder morphology, and udder health of East Friesian ewes. For that purpose a total of 80 East Friesian ewes, from 2nd to 4th lactation, with symmetrical udders, without visible (clinical) signs of mastitis were involved in this study. Until weaning at average age of 60 +/- 5 days lambs suckled their mothers exclusively. During milking period regular milking controls (on a monthly basis) were carried out (AT method) and, on these occasions, individual milk samples for chemical composition analysis were taken. Three times per lactation (1st, 3rd and 5th milking control), prior to the milking, evaluation and measuring of udder morphology traits were performed. Also, during above-mentioned test-day controls (three times per lactation) one sample of half udder milk was taken with purpose of bacterial and somatic cell counts (SCC) tests. Ewes with twin and triplet lambs had significantly (P< 0.05) higher milk yield (daily and lactation milk yield) and lower (P< 0.05) average milk fat content and total solids content than ewes with single lamb. Ewes with twins and triplets had bigger and more developed udder than ewes with singles, i. e. their udders were of larger circumference (P< 0.05), larger width (P> 0.05) and depth (P> 0.05). Besides that, udders of ewes with twins and triplets had higher cistern, greater teat angle and larger teat dimensions than ewes with singles, although those differences were not statistically significant. Ewes with single lamb had teats more (P< 0.05) cranially oriented than ewes with twins and triplets. Significant (P< 0.05) differences in somatic cell count (log(10)SCC) between ewes of different litter sizes were determined, regardless of the health status of mammary gland. The higher (P< 0.05) prevalence of subclinical mastitis was observed in ewes with twin and triplet lambs than in ewes with singles. In 46% of mammary glands (udder halves) of sheep with twins and triplets a subclinical mastitis was established and even 65.8% of them undergone an infection of one or both halves of the udder during the milking period.