Effects of three weaning and rearing systems on commercial milk production and lamb growth (original) (raw)

1999, Proc. 47 th Annual Sponner …

A flock of 132 East Friesian (EF) crossbred ewes and their lambs were used to study the effects of three weaning and rearing systems on milk production and lamb growth. During the first 30 days of lactation, ewes were either weaned from their lambs at 24 hr post-partum and then machine milked twice daily (DY1), separated from their lambs for 15 hr from late afternoon through early morning and machine milked once daily in the morning (MIX), or not machine milked and allowed unlimited access to their lambs (DY30). After 30 days, MIX and DY30 ewes were weaned, and ewes in all three groups were machine milked twice daily. Commercial milk yield and milk composition were recorded weekly until mid-lactation and then twice monthly until dryoff. Average lactation length (suckling + milking periods) was 176 d and was similar between weaning systems. Total commercial milk production differed (P < .001) between weaning systems (240, 205, and 149 L/ewe for DY1, MIX, and DY30 systems, respectively). During the first 30 days of lactation, commercial milk production, percentage of milk fat and protein, and somatic cell count (SCC) were lower (P < .05) for MIX ewes than for DY1 ewes (42 and 70 L/ewe of milk; 3.24 and 4.88% milk fat; 5.36 and 5.52% milk protein; 44,700 and 81,300 SCC, respectively). Approximately 30 days after lambing, commercial milk production, percentage of milk fat, and SCC were not different between weaning system groups, however percentage of milk protein was higher (P < .05) for DY30 ewes (5.30%) compared to DY1 and MIX ewes (5.07 and 5.11%, respectively). Litter size was a significant source of variation for most lactation traits, however parity and proportion of EF breeding tended not to be significant. Ewes put on a legume-grass pasture in mid-lactation had greater (P < .005) milk production and lactated for more (P < .005) days than ewes fed in drylot. Growth traits of 272 twin-orgreater-born lambs sired by EF or Texel rams were estimated for three rearing systems. Lambs were either raised artificially (ART), allowed access to their dams for nine hours per day (LMIX), or allowed unlimited access to their dams (TRAD) for approximately their first 30 days of age. Lamb weights at 30 days were similar, however at 120 d, TRAD lambs were heaviest (P < .01) compared to ART and LMIX lambs (47.8, 43.6, and 45.5 kg, respectively). From a simplified economic analysis, the MIX/LMIX system produced the greatest financial returns from milk and lamb production.