23 Neonatal Physiological Status of Cloned and Control Calves

Abstract

Health problems and mortality rates of cloned calves are major limitations of cloning technology and represent substantial economic losses as well as justifiable animal health and welfare concerns. The objectives of this study were to compare neonatal viability and physiological status of cloned and control calves. Cloned (Holstein, n = 5; Hereford, n = 3) and control (embryo transfer: Holstein, n = 3; Hereford, n = 3) calves were carried in the same group of Hereford × Angus crossbred recipient dams and were delivered by Cesarean section at term (Days 273–280) following induced labor. Additional calves (Holstein, n = 3; Hereford, n = 2) resulting from AI and delivered vaginally by their natural dams (Days 269–279) following spontaneous initiation of parturition were included as normal controls to evaluate the effects of the induction procedure. Physical evaluations and measurements of blood biochemistry (19 parameters), gases and electrolytes (9 parameters), and complete blood counts (18 parameters) were performed within 10 min of birth and at 1, 6, 12, 18, 24, 36, and 48 h after birth. Cloned calves were observed with increased occurrence of flexural limb deformities (4/8 clones, 0/9 controls; P < 0.05) and developmental delays of physical adjustment parameters such as time to suckle and stand (5/8 clones requiring >3 h; P < 0.05). Cloned calves were more variable than, but not different from, controls for most blood parameters measured. Compared with controls, at birth clones exhibited reduced red blood cell counts (6.8 and 8.6 × 109 cells/mL, clones and controls, respectively; P < 0.01), plasma bicarbonate (23.1 vs. 26.2 mmol/L; P < 0.05), and plasma glucose (39.4 vs. 73.6 mg/dL; P < 0.05). Blood urea nitrogen concentrations in clones tended to be elevated beginning 24 h after birth and were significantly greater than those in controls by 48 h (13.4 vs. 7.4 mg/dL; P < 0.01). Echocardiographic measurements at 24 h of age varied between groups (Table 1) and were indicative of circulatory abnormalities likely originating in utero for clones. The results of this study identified the physiological differences between clones and controls at birth and may be useful in the development of clinical-care protocols to maximize the health and survival of cloned calves. Table 1. Echocardiographic characteristics of cloned and control calves

Perinatal Physiology in Cloned And Normal Calves: Physical And Clinical Characteristics

“…Phenotypically, such fetuses are noted with distended vessels and hemorrhagic placentas likely due to impaired copper-mediated collagen and elastin cross-linking in vessel walls (Keen et al, 1998). It is tempting to speculate that similar abnormalities observed in late-term fetuses and newborn clones, such as enlarged umbilical vessels, placental abnormalities, heart irregularities, and changes in vessel wall plasticity (Batchelder et al, 2006), are associated with the consequences of unusually high fructose concentrations in utero. It seems reasonable to hypothesize that increased fructose concentrations may be part of the link between the aberrant placental morphology, umbilical and cardiovascular anomalies, and the increase in neonatal mortality reported in clones.…”

Parâmetros ecodopplercardiográficos de bezerros da raça Nelore originados através de transferência nuclear de células somáticas adultas - Clonagem

“…O exame ecocardiográfico das dimensões cardíacas entre bezerros clonados e bezerros produzidos por transferência de embriões até 24 horas de vida variaram entre os grupos comparados e indicaram anormalidades circulatórias que, segundo os autores, são provavelmente originadas durante o período intra-uterino (BATCHELDER et al 2006). Santos (2008) Komninou (2008) observou a ocorrência de anemia de grau moderado a grave, do tipo normocítico e normocrômico, 100 % (5/5) dos 5 bezerros clonados pelo Laboratório A, enquanto a incidência nos bezerros clonados pelo Laboratório B foi igual a 14,2 % (1/7), nos bezerros obtidos por fertilização in vitro foi igual 50,0 % (2/4) e em bezerros obtidos por monta natural foi igual a 50,0 % (2/4).…”