Newborn pigs (n = 117) were used to provide information on the relationships of degree of asphyxia during delivery, viability at birth, and some striking aspects of postnatal vitality including survival, interval between birth and first udder contact and between birth and first suckling, rectal temperature at 24 h of life (RT24), and growth rate over the first 10 d of life. The degree of asphyxia at birth was estimated from cord blood pCO2, pH, and lactate levels. Onset of respiration, heart rate, skin color, and attempts to stand during the first minute after birth were used to estimate the viability score. Neonatal asphyxia, i.e., decreased blood pH and increased blood pCO2 and lactate, was associated with the production of unusually high levels of catecholamines. The degree of asphyxia increased with late position in the birth order (P < .01) and was higher in piglets born posteriorly (P < 0.5). Further, the average blood pCO2 within a litter increased (P < .05) with litter size. The was an inverse relationship between the degree of asphyxia and the viability score (P < .001). Highly viable piglets reached the udder more rapidly (P < .001) and had a higher RT24 (P < .001) than those of low viability. Plasma glucose concentrations increased with blood pCO2 and plasma epinephrine concentrations (P < .001). Neonatal asphyxia reduced postnatal vitality by delaying the first contact with the udder (P < .03) and was associated with a lower RT24 (P < .05), growth rate (P < .001), and survival over 10 d (P < 0.06). These variables, i.e., interval between birth and first udder contact, RT24, and growth rate, were correlated with birth weight (P < .001); RT24 was also shown to decrease (P < .001) with the time taken to reach the udder. Overall, results suggest that piglet suffering from asphyxia during delivery are less viable at birth and less prone to adapt to extrauterine life.

No abstract

Asphyxia during delivery is considered a main cause of stillbirth in pigs, but piglets suffering from intermittent asphyxia during delivery are also less viable at birth and less prone to adapt to extrauterine life. In an effort to improve pig viability, one attractive solution would be to increase oxygen supply through oxygen inhalation by the newborn pig. The objective of this study was to test effects of oxygen inhalation immediately after birth on various physiological parameters and piglet survival. The experiment was performed on 252 Piétrain x Large White piglets, half of them reoxygenated immediately after birth. They were maintained during 20 min in a chamber where oxygen concentration was monitored at 40% and were then put back with the sow and the control pigs. Oxygen inhalation affected piglet metabolism. Through stimulation of oxidative metabolism (reduction of circulating levels of lactate) and lowering of the level of postnatal hypothermia (particularly for the lightest pigs), oxygen inhalation increased piglet viability and reduced mortality during the 1st d of life by 75% (2 vs 8%). No additional effects were observed during the following days and overall mortality between birth and weaning at 21 d was reduced from 12 to 8%.

Bidimensional electrophoresis was used to compare sarcoplasmic protein profiles of early post-mortem pig semimembranosus muscles, sampled from pigs of different HAL genotypes (RYR1 mutation 1841T/C): 6 NN, 6 Nn, 6 nn. ANOVA showed that 55 (18%) of the total of 300 matched protein spots were influenced by genotype, and hierarchical clustering analysis identified 31 (10% of the matched proteins) additional proteins coregulated with these proteins. Fold-changes of differentially expressed proteins were between 1.3 and 21.8. Peptide mass fingerprinting identification of 78 of these 86 proteins indicates that faster pH decline of nn pigs was not explained by higher abundance of glycolytic enzymes. Results indicate further that nn muscles contained fewer proteins of the oxidative metabolic pathway, fewer antioxidants, and more protein fragments. Lower abundance of small heat shock proteins and myofibrillar proteins in nn muscles may at least partly be explained by the effect of pH on their extractability. Possible consequences of lower levels of antioxidants and repair capacities, increased protein fragmentation, and lower extractability of certain proteins in nn muscles on meat quality are discussed.

To determine to what extent exposure to high ambient temperature and feeding level affect tissue energy metabolism in piglets, regional blood flow and oxidative capacity of tissues were evaluated in sixteen 21.8 ± 2.8 kg pigs. At 5 weeks of age, littermates were divided into three groups and acclimated to the treatment for 25 days. One group was reared at 33°C and fed ad libitum (33AL, n= 6) while the other two groups were maintained at 23°C and either pair‐fed on the basis of the food consumption of their 33AL littermates (23PF, n= 5), or fed ad libitum (23AL, n= 5). Regional blood flow was determined in conscious pigs by injection of coloured microspheres, which were recovered in different tissues after slaughter. Activities of cytochrome oxidase and cytochrome aa3 content were measured in tissue homogenates of heart, longissimus dorsi and rhomboideus muscles, liver and small intestine. There was decreased blood flow to internal adipose tissue (42%) and increased blood flow to peripheral tissues (skin, 44%) and tissues implicated in respiratory evaporative heat loss (diaphragm, 45%, lungs, 59%) at 33°C compared to 23°C, which can be viewed as an effective mechanism for increasing heat loss at high temperature. In addition, the concomitant decrease in blood flow (49%) and slight reduction of oxidative capacities in both muscles at 33°C might contribute to the reduction in thermogenesis, but these effects were also observed when the feeding level was reduced at thermal neutrality (23PF group). In the viscera (intestine, liver), blood flow was decreased in the two groups on a restricted food intake (about 50% of 23AL), independently of environmental temperature. The results suggest that most of the mechanisms associated with the reduction in energy expenditure during warm acclimation are related to the adaptive reduction in food intake.