No abstract

In pig production, the management of piglets by batch lactation due to the increase in litter sizes of sows may result in intermittent early neonatal maternal separation (NMS). We speculated that NMS may affect the piglets cognitive growth performance and health. To determine the extent of the effect, 12 litters of crossbred piglets (Large White × Duroc × Min-pig) were used in this trial. Piglets in the control (Con) group (n=6) were given a standard feeding method during lactation. Piglets in the experimental group (n=6) were subjected to the NMS model, in which sows were led out of the enclosure with food every day (8:00–11:00 and 13:00–16:00) starting from postnatal day (PND) 7. During the separation, the piglets were supplemented with milk. All experimental piglets were weaned on PND 35. The piglets were observed for aggression, play, mutual sniffing, and exploratory behavior on PNDs 7, 8, 21, 22, 34, 35, 38, 39, 51, 52, 64, and 65. Physiological indicators, namely serum adrenaline, cortisol, interleukin (IL)-1β, IL-4, IL-6, and tumor necrosis factor (TNF)-α were measured on PNDs 35, 38, and 65, while piglet growth performance was evaluated during suckling and 1 month after weaning. The results showed that aggressive behavior in the MS group was significantly higher than that in the Con group (P < 0.05). Playful and mutual sniffing behaviors in the MS group were significantly lower than those in the Con group except for PNDs 38 and 39 (P < 0.05). Active exploratory behavior in the MS group was significantly higher than that in the Con group on PNDs 7 and 8, and PNDs 21 and 22 (P < 0.05). The frequency of belly-nosing behavior was significantly higher in the MS group than that in the Con group except for PNDs 64 and 65 (P < 0.05). Compared with the Con group, epinephrine, IL-1β, IL-6, and TNF-α concentrations on PNDs 35, 38, and 65 were significantly increased in the MS group (P < 0.01), while IL-4 concentration was significantly decreased (PND 35: P < 0.05; PNDs 38 and 65: P < 0.01). Compared with the Con group, the piglet diarrhea rate in the MS group during suckling was significantly increased (P < 0.01), the weaning weight was significantly decreased (P < 0.05), and it had no significant effect on the body weight at the end of the trial (P > 0.05). In conclusion, the early intermittent NMS created stress and affected the growth performance of piglets during suckling. However, the growth rate was improved by compensatory measures during late weaning.

In actual production, because increase of sows litter size, the management of piglets in split-suckling leads to intermittent neonatal maternal separation (NMS). Early lactation is a critical period of cognitive development in the piglets' brain. The experiment hypothesizes that intermittent NMS may affect piglets' neurological development and cognitive ability. To determine the extent of effects of NMS on the piglets' prefrontal cortex cognitive development, the control group (Con group, n=53) was set up with no NMS, the experimental group (MS group, n=53) was set up with MS for 4 h/day, and the piglets were milk supplemented during the separation period and weaned until 35d. Twelve piglets at postnatal day (PND) 35 were selected from each group for cognitive assessment. Three PND35 piglets from each group were slaughtered, and collected prefrontal cortex samples for reference transcriptome sequencing. Following bioinformatics analysis, GO enrichment and KEGG enrichment analysis as well as candidate gene screening were performed for differentially expressed genes. Finally, quantitative reverse transcription PCR (qRT-PCR) was used to verify the sequencing data were accurate. The results showed that, in the spatial holeboard discrimination task, the working memory and reference memory of piglets in the MS group were significantly lower than those in the Con group (P < 0.01). In the new object recognition task, the MS group was significantly lower than the Con group in the number of exposure to new objects and discrimination index (P < 0.01). In the prefrontal cortex of the MS group, 349 up-regulated, 151 down-regulated differential genes, and 584 significant GO entries were discovered. Screening for 9 genes associated with cognition at large differential multiples. qPCR validation results showed that MC4R, GRP, CYFIP2, NMB, CPEB1, ADCYAP1 were significantly downregulated and MAG, PLP1, CPEB4 were significantly upregulated. Light microscopy results showed changes in the morphological structure of neuronal cells and microglia. In summary, intermittent NMS may impair partial cognitive function in piglets by damaging the structure of the prefrontal cortex.

Transportation of livestock is unavoidable in animal production. A total of 72 piglets were randomly divided into the CON group and the TSG group, and the piglets in CON group were transported for two hours. The purpose of this study was to determine the effects of short-distance road transportation lasting 2 h on the jejunum of weaned piglets. Our results showed that compared with the control group, there was no impact on the growth performance of piglets in the transport group (P &gt; 0.05). The concentrations of cortisol, heat shock protein (HSP)70, HSP90, C-reactive protein, interleukin (IL)-6, IL-8, IL-12, and interferon-γ and the activity of reactive oxygen species were increased in the jejunum of piglets in the transport group (P &lt; 0.05 compared with the control group). The concentrations of glutathione peroxidase, claudin-1, occludin, and zonula occludens-1 showed no between-group differences (P &gt; 0.05). Regarding intestinal morphology, the transport group showed infiltration of a small amount of lymphocytes into the jejunum mucosa epithelium that was accompanied by edema of the lamina propria, whereas the control group showed no obvious abnormalities. At the genus level, in the transport group, the 16S rRNA sequencing revealed a downward trend in the relative abundance of Lactobacillus and an upward trend in the relative abundance of Muribaculaceae_unclassified. There was also increased mRNA expression of genes associated with inflammation in the transport group, but the genes and pathways related to apoptosis were not activated. In summary, weaned piglets undergoing 2 h of short-distance road transportation showed stress and inflammatory reactions of the jejunum but did not exhibit oxidative damage or activation of the apoptosis pathway of the jejunum. Furthermore, the growth performance of the piglets was not affected by the trip.