Yawning and Penile Erection Frequencies Are Resilient to Maternal Care Manipulation in the High-Yawning Subline of Sprague-Dawley Rats.

Yawning is a stereotyped behavioral pattern characterized by wide opening of the mouth associated with deep inspiration followed by short expiration. All vertebrate species yawn, but with low frequencies. We obtained two sublines of Sprague-Dawley (SD) rats by a strict inbreeding process: one with a high-yawning frequency (HY) of 20 yawns/h, which is one order of magnitude higher with respect to the low-yawning frequency (LY) subline, with 2 yawns/h. Outbred SD rats had a yawning frequency of 1 yawn/h. HY dams had a different organization of maternal care with respect to that displayed by LY and SD dams because HY dams constructed lower quality nests and had more re-retrieving and atypical retrieving. The aim of this study was to analyze the changes in maternal care using in- and cross-fostering between the sublines and SD dams and to measure spontaneous and dopaminergic-induced yawning, penile erections, grooming and scratching bouts. We also measured the expression of dopamine D2 receptors in the striatum using Western blot analysis. Our results showed that HY male rats reared by SD or LY dams did not significantly differ in yawning frequencies with respect to HY male rats reared by mothers of their own phenotype. Maternal care did not differ between sublines and SD dams independent of the litter they reared. However, LY rats reared by HY dams showed a significant increase in the number of spontaneous penile erections. Importantly, in-fostered HY male rats had the highest number of yawns induced by systemic administration of (-)-quinpirole supporting that higher maternal care display can influence the frequency of dopaminergic-induced yawning. In fact HY male rats in all conditions yawned more than did LY and SD male rats independent of the dam that raised them supporting a strong influence of genetic background. However SD male rats raised by LY dams showed significantly increased the dopamine D2 receptor expression. In conclusion, maternal care and the environmental nest conditions during the lactation period did not change the phenotypic characteristics of the yawning sublines supporting that their genetic background is fundamental for the expression of spontaneous or dopaminergic-induced yawning.

Repeated cross-fostering affects maternal behavior and olfactory preferences in rat pups.

Disturbances in early mother-infant relationships are strongly associated with changes in the development of a number of physiological and behavioral systems in the neonate that can create a complex change in patterns of vulnerability throughout life. Institutionalized children, despite receiving adequate care, display important behavioral changes in adult life, and such changes are strongly associated with a lack of selective and consistent attachment to the maternal figure in early life. It is not yet clear how human adoption processes alter the mother-infant relationship early in life. Here, to mimic the situation of human adoption and explore the impact on the formation of attachment between the infant and a caregiver, we use a repeated cross-fostering (RCF) model in rodents in two postnatal periods, postnatal days (PND) 1 to 3 (early RCF) and 9 to 11 (late RCF). Early exposure but not late exposure to RCF reduces the pups' preference for the odor of the mother figure. Moreover, early exposure and slightly later exposure to RCF reduce maternal care and motivation in collecting the pups and bringing them to the nest. The RCF protocol creates an unstable environment for mother-pup interaction, but it seems to affect learned attachment to the mother only when it occurs during the corresponding sensitive period of development.

Cross-fostering reduces obesity induced by early exposure to monosodium glutamate in male rats.

Maternal obesity programmes a range of metabolic disturbances for the offspring later in life. Moreover, environmental changes during the suckling period can influence offspring development. Because both periods significantly affect long-term metabolism, we aimed to study whether cross-fostering during the lactation period was sufficient to rescue a programmed obese phenotype in offspring induced by maternal obesity following monosodium L-glutamate (MSG) treatment. Obesity was induced in female Wistar rats by administering subcutaneous MSG (4 mg/g body weight) for the first 5 days of postnatal life. Control and obese female rats were mated in adulthood. The resultant pups were divided into control second generation (F2) (CTLF2), MSG-treated second generation (F2) (MSGF2), which suckled from their CTL and MSG biological dams, respectively, or CTLF2-CR, control offspring suckled by MSG dams and MSGF2-CR, MSG offspring suckled by CTL dams. At 120 days of age, fat tissue accumulation, lipid profile, hypothalamic leptin signalling, glucose tolerance, glucose-induced, and adrenergic inhibition of insulin secretion in isolated pancreatic islets were analysed. Maternal MSG-induced obesity led to an obese phenotype in male offspring, characterized by hyperinsulinaemia, hyperglycaemia, hyperleptinaemia, dyslipidaemia, and impaired leptin signalling, suggesting central leptin resistance, glucose intolerance, impaired glucose-stimulated, and adrenergic inhibition of insulin secretion. Cross-fostering normalized body weight, food intake, leptin signalling, lipid profiles, and insulinaemia, but not glucose homeostasis or insulin secretion from isolated pancreatic islets. Our findings suggest that alterations during the lactation period can mitigate the development of obesity and prevent the programming of adult diseases.

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights / Comportamento e desempenho de crescimento de leitões com baixo peso ao nascer uniformizados com leitões de maior peso em fêmeas suínas multíparas

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (>1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets.(AU)

O objetivo do estudo foi avaliar o comportamento, a taxa de sobrevivência pré-desmame e o desempenho de crescimento de leitões leves ao nascer uniformizados com leitões de maior peso ao nascer (PN). Os leitões foram transferidos para 60 fêmeas e divididos em três grupos (G; n=20): G1 - 12 leitões de baixo PN (0,80-1,25kg); G2 - seis leitões de baixo PN e seis com PN intermediário (1,40-1,60kg); e G3 - seis leitões de baixo PN e seis leitões pesados (>1,70kg). Para a análise, os grupos G2 e G3 foram subdivididos em LG2 (seis G2 leitões leves); IG2 (seis G2 leitões de peso intermediário); LG3 (seis G3 leitões leves) e HG3 (seis G3 leitões pesados). Observações de comportamento foram realizadas nos dias 1, 2, 4 e 6 (observações visuais diretas) e nos dias 3 e 5 (gravações) após o nascimento. A porcentagem de mamadas perdidas foi maior no grupo LG3 quando comparado aos grupos LG1, IG2 e HG3, nos dias 1 e 2. No dia 4, leitões leves (LG1, LG2 e LG3) perderam maior número de mamadas do que os grupos IG2 e HG3. No dia 3, a gravação mostrou maior porcentagem de perda de mamadas nos grupos LG1, LG2 e LG3 do que no grupo HG3. No dia 1, o número de brigas durante a mamada foi maior nos grupos IG2 do que nos grupos LG1 e LG3. Também no dia 1, o número de brigas e porcentagem de leitões envolvidos em brigas, durante 15 minutos após a mamada, foi maior nos grupos LG1, LG3 e HG3 do que no grupo LG2. Brincadeiras foram mais observadas no dia 2 nos grupos IG2 e HG3 quando comparado aos grupos LG1, LG2 e LG3. Leitões leves (LG1, LG2 e LG3) apresentaram peso semelhante nos dias 4, 8, 12 e 16 após o nascimento, independentemente de serem misturados ou não com leitões pesados. No entanto, a taxa de sobrevivência até o dia 16 foi mais comprometida nos leitões do grupo LG3 do que nos outros grupos. Apesar da falta de influência do peso das leitegadas no crescimento de leitões de baixo PN, a taxa de sobrevivência indicou que estes não devem ser misturados com leitões de maior PN.(AU)

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights / Comportamento e desempenho de crescimento de leitões com baixo peso ao nascer uniformizados com leitões de maior peso em fêmeas suínas multíparas

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (>1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets...

O objetivo do estudo foi avaliar o comportamento, a taxa de sobrevivência pré-desmame e o desempenho de crescimento de leitões leves ao nascer uniformizados com leitões de maior peso ao nascer (PN). Os leitões foram transferidos para 60 fêmeas e divididos em três grupos (G; n=20): G1 - 12 leitões de baixo PN (0,80-1,25kg); G2 - seis leitões de baixo PN e seis com PN intermediário (1,40-1,60kg); e G3 - seis leitões de baixo PN e seis leitões pesados (>1,70kg). Para a análise, os grupos G2 e G3 foram subdivididos em LG2 (seis G2 leitões leves); IG2 (seis G2 leitões de peso intermediário); LG3 (seis G3 leitões leves) e HG3 (seis G3 leitões pesados). Observações de comportamento foram realizadas nos dias 1, 2, 4 e 6 (observações visuais diretas) e nos dias 3 e 5 (gravações) após o nascimento. A porcentagem de mamadas perdidas foi maior no grupo LG3 quando comparado aos grupos LG1, IG2 e HG3, nos dias 1 e 2. No dia 4, leitões leves (LG1, LG2 e LG3) perderam maior número de mamadas do que os grupos IG2 e HG3. No dia 3, a gravação mostrou maior porcentagem de perda de mamadas nos grupos LG1, LG2 e LG3 do que no grupo HG3. No dia 1, o número de brigas durante a mamada foi maior nos grupos IG2 do que nos grupos LG1 e LG3. Também no dia 1, o número de brigas e porcentagem de leitões envolvidos em brigas, durante 15 minutos após a mamada, foi maior nos grupos LG1, LG3 e HG3 do que no grupo LG2. Brincadeiras foram mais observadas no dia 2 nos grupos IG2 e HG3 quando comparado aos grupos LG1, LG2 e LG3. Leitões leves (LG1, LG2 e LG3) apresentaram peso semelhante nos dias 4, 8, 12 e 16 após o nascimento, independentemente de serem misturados ou não com leitões pesados. No entanto, a taxa de sobrevivência até o dia 16 foi mais comprometida nos leitões do grupo LG3 do que nos outros grupos. Apesar da falta de influência do peso das leitegadas no crescimento de leitões de baixo PN, a taxa de sobrevivência indicou que estes não devem ser misturados com leitões de maior PN...

Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities.

The objective of this study was to evaluate the effect of colostrum intake on mortality and growth performance of piglets until 42 days of age, taking into account the birth weight, and parity order of sows. Colostrum intake from birth to 24h after birth was estimated in 300 piglets each from primiparous and multiparous sows. The piglets were cross-fostered in 25 primiparous and 25 multiparous sows at 25.9±0.09 h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24h after farrowing), at 10 and 20 days of age. For high birth weight piglets (HBW - >1.3-1.7 kg) the probability of death was low regardless of their colostrum intake. Intermediate birth weight (IBW - >1.2-1.3 kg) and low birth weight (LBW - 1.1-1.2 kg) piglets had the same probability of death compared to HBW piglets, when colostrum intake reached 200 and 250 g, respectively. The probability of low performance (<9.5 kg) was lower in HBW than in LBW and IBW piglets, regardless of colostrum intake. HBW piglets had higher weight at 14, 20, 28 and 42 days of age (P<0.05) than LBW piglets, and higher weight than IBW piglets at 28 and 42 days. Colostrum intake >250 g increased (P<0.05) the weight of piglets at 28 and 42 days of age, regardless of their birth weight. Piglets from primiparous biological dams consumed less colostrum (P<0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24h after birth and their performance were similar (P>0.05). Piglets suckled by primiparous foster sows showed lower weight (P<0.05) at 20, 28 and 42 days than piglets suckled by multiparous sows. Piglets that died before 42 days of age had lower (P<0.05) birth weight, colostrum intake and serum IgG at 24 h after birth compared to surviving piglets, and lower values were also observed in piglets with low performance compared to high (>9.5 kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P>0.05) between high and low performance piglets. In conclusion, both colostrum intake and birth weight are important for survival and growth of suckling piglets. LBW and IBW piglets are more dependent on colostrum intake than HBW piglets to assure higher survival and better development up to 42 days of age. Piglets suckled by multiparous sows have better development than those suckled by primiparous sows.