Effect of weaning system on commercial milk production and lamb growth of East Friesian dairy sheep.

East Friesian crossbred ewes (n = 99) and their lambs (n = 232) were used to study the effects of three weaning systems on milk production and lamb growth. Prior to parturition, a ewe and her lambs were assigned to one of the following three treatments for the first 28 +/- 3 d of lactation: 1) ewes weaned from their lambs at 24 h postpartum, ewes machine milked twice daily, and their lambs raised artificially (DY1); or 2) beginning 24 h postpartum, ewes separated from their lambs for 15 h during the evening, ewes machine milked once daily in the morning, and their lambs allowed to suckle for 9 h during the day (MIX); or 3) ewes not machine milked and exclusively suckled by their lambs (DY30). After the treatment period, lambs were weaned from MIX and DY30 ewes, and all three groups were machine milked twice daily. Daily commercial milk yield and milk composition were recorded weekly or twice monthly, and lambs were weighed at weaning or at 28 d and at approximately 120 d of age. Average lactation length (suckling + milking period) was 183 +/- 5 d and was similar among weaning systems. Differences among weaning systems for milk yield, milk fat and protein percentages, and somatic cell count were highly significant prior to and around weaning, and became nonsignificant by 6 wk in lactation. Total commercial milk production was greatest for DY1 and MIX ewes (261 +/- 10 and 236 +/- 10 kg/ewe, respectively) and least for DY30 ewes (172 +/- 10 kg/ewe). Daily gain of lambs to 30 d and weight at 30 d were similar regardless of weaning system; however, by 120 d, DY30 lambs tended to be heaviest, MIX lambs intermediate, and DY1 lambs lightest (47.3 +/- 1.6, 45.9 +/- 1.8, and 43.7 +/- 1.2 kg, respectively). Overall financial returns for milk and lamb sales were greatest for the MIX system because of the increase in marketable milk during the first 30 d of lactation compared with the DY30 system and because of acceptable 120-d lamb weights without the expenses of artificial rearing compared with the DY1 system. A mixed system of suckling and milking during early lactation appears to be a valuable management tool for dairy sheep production.