The effect of Slow-Release Bolus of Copper on Performance and Some Blood Metabolites of Lori-Bakhtiari Pregnant Ewes and Their Lambs

 The provision of nutrients during the late gestation not only affects maternal status and reproductive performance, but also affects prenatal and postnatal litter growth and offspring’s health. Although trace elements are needed by the body in small amounts, they are essential nutrients for several metabolic functions such as growth, development, reproduction, and immunity. Copper (Cu) is often one of the most limiting trace elements for the fetus and neonate for normal development and copper play a major etiologic role in decrease of fetal growth and development. Deficiency of copper impairs fetal growth and causes serious consequences and can cause death. When intakes of Cu are deficient, maternal transfer of Cu to the fetus is insufficient for normal development, and abnormalities to the central nervous system, skeleton, and metabolism result. In ruminants, newborn animals are dependent on their dams for transferring nutrients via the placenta and mammary glands. To our knowledge, little information is available on the effects of maternal supplementation of copper via intra-ruminal administration of slow-release bolus at the late gestation on the copper status of ewes and their lambs. Because the slow-release ruminal bolus cannot be used in the newborn lambs until weaning, this study aimed to determine the effects of maternal supplementation of copper via intra-ruminal administration of slow-release boluses at the late gestation (8 weeks prepartum) on performance and some blood metabolites of ewes and their lambs until weaning.

To evaluate the performance and changes in some blood parameters of lambs born from ewes receiving slow-release boluses of copper, 80 Lori-Bakhtiari ewes (The fourth pregnancy with a body condition score 3 to 3.5) were divided into two groups of 40 heads each in a completely randomized design. Treatments were 1) control ewes and 2) ewes received slow-release boluses of copper, 60 days prepartum. After parturition, birth weight, sex, and the birth status of lambs (singlet or twin) were recorded. Lambs were weighed at birth and weaning at age 90 days. On the first day, days 10 and 60 postpartum, blood samples were taken from the ewes, while the blood samples of their lambs were taken at age 10 and 60 days. Serum samples were used to determine copper and ceruloplasmin concentrations in the ewes and their lambs, while iron, zinc, hematocrit, red blood and white cells, and hemoglobin were only determined in the born lambs.

The serum concentration of copper in the ewes were within the normal physiological range of 0.55 to 0.95 mg/l. Serum copper and ceruloplasmin concentrations of ewes at the first day of experiment were lower compared to days 10 and 60 postpartum (P<0.05), but similar between days 60 and 10 postpartum (P>0.05). Lambs born from ewes receiving slow-release bolus of copper had higher weaning weight, average daily weight gain, copper and ceruloplasmin concentrations, hematocrit percentage, red and white blood cell counts, and hemoglobin concentration compared to those born from control ewes (P<0.05). The serum concentration of ceruloplasmin was higher in lambs born from ewes receiving two boluses than those born from ewes receiving only one bolus (P<0.05). Ceruloplasmin concentration is also a reliable indicator of copper deficiency as it carries between 60-95 percent of serum copper, and changes in serum copper concentration usually parallel the ceruloplasmin concentration in the blood. Lambs born from ewes in the control group had lower serum copper concentrations, and 3 lambs in this group showed the symptoms of paralysis, especially in their hind legs, imbalances, dog sitting, and lost appetite. Adequate maternal intake of Cu is essential for development of the central nervous system (CNS) of the embryonic lamb. Consequences of Cu deficiency during intrauterine life may include gross brain lesions, with affected lambs born dead or dying shortly after birth. 

Overall, serum copper concentrations of ewes were in the normal range, but lambs born from ewes received slow-release copper bolus had greater weaning weight, average daily weight gain, serum copper and ceruloplasmin concentrations, hematocrit percentage, hemoglobin concentration, and red blood cell count compared to those born from control ewes. In conclusion, the results of the present study showed that lambs were benefited from copper supplementation of their dams via intra-ruminal administration of slow-release boluse of copper in the late gestation.