Maternal arginine supplementation enhances thermogenesis in the newborn lamb

Body temperature maintenance is one of the most important physiological processes initiated after birth. Brown adipose tissue (BAT) is an essential mediator of thermogenesis in many species and is responsible for 50% of the heat generated in the newborn lamb. To determine if maternal arginine supplementation could enhance thermogenesis in the neonate, we randomly assigned 31 multiparous Suffolk ewes, gestating singletons or twins, to receive intravenous injections of either l-arginine (27 mg/kg body weight; n = 17) or sterile saline (n = 14) three times daily from day 75 to 125 of gestation (term = 147). Following parturition, lambs were removed from their mothers and subjected to 0 °C cold challenges at 4 and 22 h of age. Rectal temperatures were higher for the duration of the cold challenges in lambs from arginine-treated ewes compared with lambs from saline-treated ewes (P < 0.05). Elevated rectal temperatures were associated with increased (P < 0.05) circulating glycine and serine concentrations in lambs. The mRNA expression of genes related to BAT function changed over time, but not between lambs from arginine-treated vs. saline-treated ewes. Results indicate that maternal arginine treatment increases neonatal thermogenesis after birth. Although the underlying mechanisms remain to be elucidated, these data are a first step in improving neonatal survival in response to cold.

Lumped Thermal Model of a Newborn Lamb and a Liquid Ventilator in Total Liquid Ventilation

Total liquid ventilation (TLV) is an emerging and promising mechanical ventilation method in which the lungs are filled with a breathable liquid. Perfluorocarbon (PFC) is the predominant liquid of choice due to its high O2 and CO2 solubility. In TLV, a dedicated liquid ventilator ensures gas exchange by renewing a tidal volume of PFC, which is temperature-controlled, oxygenated and free of CO2. A fundamental difference between TLV and conventional mechanical ventilation relates to the fact that PFCs are approximately 1500 times denser than air. This high density provides PFCs with a large heat capacity, turning the lungs into an efficient heat exchanger with circulating blood. The originality of this study is the development of a lumped thermal model of the body as a heat exchanger coupled to a liquid ventilator. The model was validated with an animal experimentation on a newborn lamb with the Inolivent-5.0 liquid ventilator prototype. TLV was initiated with a fast hypothermia induction, followed successively by a slow posthypothermic rewarming, a fast rewarming and finally a second fast hypothermia induction. Results demonstrate that the model was able to aptly predict, in every phase, the temperature of the lungs, the eardrum, the rectum as well as the various compartments of the liquid ventilator.

The Effect of Experimentally Induced Vitamin E and Selenium Deficiency on Erythrocytes Osmotic Fragility and Phagocytosis in Pregnant Awassi Ewes and Their Newborn Lamb

Experimental induction of vitamin E and selenium deficiency using deficient diet was carried out on fourteen pregnant Awassi ewes and their newborn lambs to study the effect of the deficiency on erythrocytes osmotic fragility and phagocytosis. From the fourteen deficient ewes, seven were vaccinated with Rev I vaccine and seven ewes as control group, and their newborn lambs were used in the study. Results were showed increased in the concentration of saline solution in start and complete erythrocyte hemolysis in deficient lambs (0.52 ± 0.01 and 0.54 ± 0.01) and (0.42 ± 0.01 and 0.44 ± 0.00) respectively and in deficient ewes (0.53 ± 0.01 and 0.54 ± 0.01) and (0.43 ± 0.01 and 0.44 ± 0.00) respectively. Results showed a low phagocytic index in deficient lambs (9.40 ± 0.87 and 10.60 ± 1.16) and in deficient ewes (12.14 ± 0.85 and 12.42 ± 0.75) compared to phagocytic index in control lambs (43.85±0.91) and in control ewes (43.14 ±0.91).