RUMEN-PROTECTED BYPASS FAT FOR DAIRY EWE COMMERCIAL MILK PRODUCTION

The effects of fat supplementation and weaning system on commercial milk yield and milk composition were determined on 129 East Friesian crossbred ewes. Prior to lambing, ewes were randomly assigned to one of two weaning systems. The DY1 system involved weaning of ewes from their lambs within 24 to 36 hr post-partum and then twice-daily machine milking. In the MIX system, ewes had access to their lambs during the day, were separated from their lambs overnight, and were machine milked once daily in the morning. After approximately 30 days in lactation, lambs were weaned from the MIX system ewes, and all ewes were machine milked twice daily. Additionally, calcium salts of fatty acids (CSFA) were premixed in a concentrate ration and fed to all ewes (100 grams/ewe/day) for 2 two-week periods during early lactation. Each CSFA feeding period was separated by two weeks of not feeding CSFA. Milk yield was measured weekly, and milk samples were analyzed for percentage of milk fat and protein and somatic cell count. During the first 30 days of lactation, DY1 ewes produced 38% more com- mercial milk, 73% more kilograms of fat, 42% more kilograms of protein, had significantly higher percentages of milk fat (5.90 vs 2.51%, respectively), and similar percentages of milk protein compared to MIX ewes. Following weaning, commercial milk, fat, and protein yields from MIX ewes were significantly more than those of DY1 ewes. CSFA supplementation did not influence commercial milk yield. Percentage and yield of milk fat was significantly higher for DY1 ewes that received CSFA supplementation compared to unsupplemented DY1 ewes. Conversely, for the MIX system, percentage and yield of milk fat was unchanged between CSFA-supplemented and unsupplemented ewes prior to complete weaning at 30 days post- partum. For both the DY1 and MIX systems, percentage and yield of milk protein tended to be suppressed in CSFA-supplemented vs unsupplemented ewes. Somatic cell count was not signifi- cantly affected by either weaning system or CSFA supplementation. As previously confirmed in this flock, weaning system significantly influences commercial milk production and composition during the first 30 days of lactation. CSFA supplementation did not increase percentage nor yield of milk fat in partially suckled ewes. CSFA supplementation of dairy ewes in early lactation induces a slight suppression in milk protein and increases milk fat yield provided that ewes have been completely weaned from their lambs. According to a proposed milk purchase price sched- ule from one sheep-milk processing facility where payments are based on milk fat percentage and other indicators of milk quality, CSFA-supplemented milk appears to offer greater financial returns compared to unsupplemented milk.