Plane of energy nutrition on blood metabolites, milk production and lamb growth for Friesian ewes

Abstract
This study was conducted to evaluate the effects of a low metabolizable energy (LME) and high metabolizable energy (HME) diet on twenty-two Friesian ewes, milk production and nutritional status and their lambs. On day 100 of gestation, ewes were divided into metabolizable energy (ME) groups and fed alfalfa hay and rolled corn that provided either 80% low metabolizable energy (LME) or 140% high metabolizable energy (HME) of recommended ME requirement based on published NRC (2007) values for 70 kg ewes carrying twins, nursing twins and producing 1.5 to 2.9 kg milk/day. Treatment period was from day -42 of gestation (approximately six weeks) to six weeks post parturition. Lamb treatments included nursing from ewes on HME, LME and lambs artificially reared (AR) on goat’s milk. Body weight and backfat (BF) were measured weekly for each ewe and BW weekly for lambs. Blood samples were collected weekly from ewes during the experiment and from neonatal lambs. Blood glucose, plasma urea nitrogen (PUN), creatinine, total protein (TPP) and triglycerides were analyzed to assess the nutritional status of both ewes and lambs. Weekly milk samples for each ewe were analyzed for butter fat, protein, lactose, milk urea nitrogen (MUN), somatic cell count (SCC), and solids-not-fat (SNF). Ewe body weight was not different between treatments. There were differences in BF with the HME group having more BF than the LME group. Ewe blood glucose, PUN, and TPP were significant for week. Milk fat (MF) percentage, daily fat produced, and lactose were affected by energy treatment. The LME group displayed both higher MF percentages and daily fat in milk while the HME group had higher concentrations of milk protein and lactose percentages. Lamb weight showed weekly and treatment affects for HME, LME and AR) with the HME group weighing the most by the end of the experiment. Concentrations of plasma glucose, PUN, and creatinine resulted in differences with the HME group having the highest concentration of each component. Our results indicate that perinatal nutrition effects both the ewe and lamb as well as milk production. Because of the lower energy intake of the LME group, we see that nutrient partitioning occurs enabling the ewe to allocate energy towards growth of the fetus and to produce enough milk to sustain growth of the lamb post placental drop. This partitioning of energy came at the expense of body condition for the LME group, and to a lesser extent to the HME group, in order to produce adequate milk for the offspring.