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Prenatal development is mainly dependent on a close interrelation between nutritional supply use and regulation by hormones and growth factors. Mechanisms during early embryonic development are sensitive to manipulation through selected management strategies of the sow and modifications of this strategy may serve as a model for the examination of molecular and cellular events controlling early embryonic growth. The administration of growth hormone (GH) to pregnant sows affects the development of fetuses in a manner dependent on the gestational period of treatment, therefore suggesting that maternal GH plays a significant role in prenatal development. In addition, in well-fed and feed-restricted gilts, treatment with porcine somatotropin (pST) during early to mid-pregnancy promotes the growth of their placenta and/or fetuses. Due to an exponential increase in research exploring the role of ST in growth biology, collectively, these studies resulted in an unprecedented increase in our understanding of how ST affects growth of domestic animals. Thus, the main purpose of this review is to provide an overview of the remarkable biological effects that pST has on pig fetal growth.

The aim of this study was to evaluate the effect of porcine recombinant somatotropin (rpST) administered to piglets during their first week of life, on metabolic and somatometric variables. A total of 220 piglets born from 40 hybrid Landrace x Large White sows were used. Piglets were randomly assigned to either Group 1 (G1, Control, n = 106) or Group 2 (G2, rpST treatment, n = 114). The rpST dose was 1mg/kg every 24h during 7 consecutive days. Serum pH at birth showed significant differences between groups (7.42 ± 0.47 and 7.31 ± 0.59), although this difference dissapeared on day 8. There was a significant increase (P < 0,001) in plasma glucose levels for the treated group on day 8 (68.78 ± 10.44 and 103.71 ± 18.44). Average daily weight gain was also higher for the somatotropin treated group compared to the control (137.25 ± 31.31 and 209.21 ± 45.97). Comparisons for interaction between treatment and sex showed dramatic differences (P < 0,001) for glucose, lactate and weight gain for the males from G2when compared to the females from the same experimental group on day 7 post-treatment. Piglets treated with rpST showed significant differences in abdominal perimeter (28.67 ± 4.41 and 31.79 ± 3.74), dorsal length (28.42 ± 2.66 and 30.21 ± 4.70), and ham roundness (18.79 ± 2.62 and 22.38 ± 2.98). There is an ongoing research that will allow to determine the composition of body mass (bone or muscle) in the treated piglets. &nbsp, Con el fin de evaluar el efecto de la administración de la somatotropina recombinante porcina (rpST) en lechones, sobre las variables metabólicas y somatométricas durante la primera semana de vida, se evaluaron un total de 220 lechones al nacimiento de 40 cerdas híbridas Landrace x Large White. Los lechones fueron clasificados aleatoriamente en dos grupos. El Grupo 1 conformado por 106 lechones (Grupo testigo) y el grupo 2 por un total de 114 lechones (Grupo tratado con pST). La administración de la rpST se realizó a una dosis de 1 mg/kg cada 24 h durante siete días. En el pH al nacimiento se apreciaron diferencias significativas (P < 0,05) en ambos grupos (7,42 ± 0,47 y 7,31 ± 0,59), fenómeno que desaparece a la semana de vida. A la semana se observó un aumento significativo (P < 0,001) en los niveles de glucosa en los lechones del G2vs. G1(103,71 ± 18,4468, 78 ± 10,44). Al final del experimento la ganancia diaria de peso fue mayor para el grupo tratado con rpST (209,21 ± 45,97) respecto al grupo testigo (137,25 ± 31,31). Al comparar el efecto del tratamiento por sexo se observaron marcadas diferencias significativas (P < 0,001) en el pH, glucosa, lactato y peso ganado en los machos del G2con respecto a las hembras del mismo grupo a los siete días postratamiento. Los lechones tratados con rpST presentaron diferencias significativas en las variables: perímetro abdominal (28,67 ± 4,41 y 31,79 ± 3,74 respectivamente), largo dorsal (28,42 ± 2,66 y 30,21 ± 4,70 respectivamente) y redondez del jamón (18,79 ± 2,62 y 22,38 ± 2,98 respectivamente). Investigación en proceso permitirá distinguir la masa corporal ganada por los lechones, en ósea o muscular. &nbsp

In order to evaluate how spontaneously born piglets could be a suitable model for the study of intrapartum hypoxia, 230 newborn piglets were studied. Out them, 8.3% (n = 19) died intrapartum, 21.7% (n = 50) were born with moderate-to-severe intrapartum hypoxia, and 70% (n = 161) were born with mild or no evidence of intrapartum distress. Piglets born without any evidence of intrapartum asphyxia weighed approximately 240 g lower than those born with intrapartum hypoxia and intrapartum-dead piglets (P0.0001). The viability score was approximately 3 units lower and the latency to contact the udder was two times longer in the piglets surviving intrapartum hypoxia than in controls (P0.0001). In comparison with the control group, metabolic acidosis was most severe among intrapartum-dead piglets followed by piglets surviving intrapartum asphyxia (P =0.002). According to a multiple linear regression analysis, pCO2 and lactate blood levels, and birth weight were identified as explanatory variables of viability score (r: 0.78; P0.001). Viability score, K+ and lactate blood levels, and birth weight were identified as explanatory variables of latency to contact the udder (r: 0.80; P0.001). In conclusion, the spontaneously-born asphyxiated piglet could be considered as a naturalistic model for the study of intrapartum asphyxia. Histopathologic and more rigorous functional and behavioral evaluations are still required to further characterize the model. (www.actabiomedica.it)

Prolonged or intermittent asphyxia in utero and during farrowing weakens piglets and renders them less capable of adaptation to extrauterine life. Piglets with lesser viability at birth have increased blood pCO2 and blood lactic acid concentrations and decreased blood pH. Moreover, the ability to thermoregulate during an acute cold stress is inversely related to umbilical blood lactate concentrations. Blood gas measurements and noninvasive estimations provide important information about oxygenation. The general goals of oxygen therapy in the neonate are to maintain adequate arterial PaO2 and SaO2, and to minimize cardiac work and the work of breathing. Arterial blood gas determinations of pCO2 provide the most accurate determinations of the adequacy of alveolar ventilation. Blood gases obtained in the immediate perinatal period can help assess perinatal asphyxia, but particular attention must be paid to the sampling site, the time of life, and the possible and proven diagnoses. The decision to obtain blood gases must be weighed by the individual clinician against the potential benefits. Current measures for restoring the acid base balance status in the newborn with perinatal asphyxia are discussed.