Effects of dietary valine supplementation during late gestation on the reproductive performance and mammary gland development of gilts

Background:Mammary gland development during late gestation in gilts is a major factor that alters the composition of colostrum and growth performance of piglets.Plasma valine is taken up and metabolized extensively by the mammary gland;however,the effects of valine on mammary gland development during late gestation are still unclear.Thirty primiparous gilts were divided into three treatment groups(n=10)and received one of the three diets starting on day 75 of gestation until the day of farrowing.The total dietary valine to lysine ratio of the three diets was 0.63(LV),0.73(MV),and 0.93(HV),respectively.Results:Dietary valine supplementation during late gestation did not affect(P>0.05)the litter size and weight at farrowing;however,the piglet weight and average daily gain at weaning were linearly increased(P<0.05)as the dietary valine increased.The highest piglet weight at weaning was observed when the gilts were provided the HV diet.Dietary valine supplementation linearly elevated(P<0.05)protein,fat and solids-not-fat and some free amino acids content in colostrum.The concentration of prolactin in plasma of gilts was linearly increased in response to valine supplementation at days 1 and 10 of lactation(P<0.05).Furthermore,with increasing dietary valine allowance,a linear increase(P<0.05)was observed in the area of the lumen of alveolus and the content of DNA,RNA,and total protein in the mammary tissues at day 1 of lactation.Moreover,the protein expression of cyclin D1,p-mTOR,p-S6,and p-4EBP1 was also linearly increased(P<0.05)in the mammary tissue at day 1 of lactation.However,no difference(P>0.05)was observed in the indices related to mammary development and the mTOR signaling pathway at day 21 of lactation.Conclusion:The results revealed that increasing the total dietary valine to lysine ratio to 0.93 during late gestation significantly enhances the piglet weight and average daily gain at weaning probably due to improved development of mammary gland.

A Virtual Reality Platform for Context-Dependent Cognitive Research in

Animal survival necessitates adaptive behav-iors in volatile environmental contexts.Virtual reality(VR)technology is instrumental to study the neural mechanisms underlying behaviors modulated by environmental con-text by simulating the real world with maximized control of contextual elements.Yet current VR tools for rodents have limited flexibility and performance(e.g.,frame rate)for context-dependent cognitive research.Here,we describe a high-performance VR platform with which to study con-textual behaviors immersed in editable virtual contexts.This platform was assembled from modular hardware and custom-written software with flexibility and upgradability.Using this platform,we trained mice to perform context-dependent cognitive tasks with rules ranging from discrim-ination to delayed-sample-to-match while recording from thousands of hippocampal place cells.By precise manipula-tions of context elements,we found that the context recogni-tion was intact with partial context elements,but impaired by exchanges of context elements.Collectively,our work establishes a configurable VR platform with which to investigate context-dependent cognition with large-scale neural recording.

Dietary energy intake affects fetal survival and development during early and middle pregnancy in Large White and Meishan gilts

This experiment was designed to determine the effects of variations in dietary energy intake on reproductive performance and gene expression of luteal and endometrium tissues in Large White(LW)and Meishan(MS) gilts during early and middle pregnancy. After insemination, 32 LW gilts were assigned to high and low(HE_Land LE_L, 14.23 and 12.56 MJ DE/kg, respectively) diet treatment groups,while 32 MS gilts were allocated to HE_M and LE_M(12.56 and 10.88 MJ DE/kg) groups. Gilts were slaughtered on days 35, 55 and 90 of gestation. The fetal survival and luteal progesterone(P_4) concentration in the HE_Lgroup were higher on day 35 but lower on day 90 of gestation compared with the LE_L group(P < 0.05) for LW gilts. However, fetal survival and luteal P_4 concentration on day 35 of gestation were greater(P < 0.05) in the LE_M group than in the HE_M group for MS gilts, but no significant difference in mid-gestation was showed. The fetal weights of both breeds were higher for the high energy diets compared with the respective control group on day 90 of gestation(P < 0.05). In addition,the m RNA levels of P_4 synthesis-related proteins had correlated with luteal P_4 concentration in both breeds. Further, endometrial levels of uteroferrin(ACP5), retinol-binding protein 4(RBP_4) and secreted phosphoprotein 1(SPP1) m RNA were upregulated in the HE_Lgroup on day 35 of gestation but ACP5 and SPP1 were downregulated on day 55 of gestation compared with the LE_Lgroup(P < 0.05) for LW gilts. In MS gilts, diet only affected the expression of SPP1(P < 0.05). Our results revealed the differential sensitivity of LW and MS breeds to variations in dietary energy intake. For LW gilts, the HE_Lgroup improved fetal survival on day 35 but a sustained high energy diet decreased fetal survival on day 90 of gestation. The differences in dietary energy intake did not influence fetal survival on day 90 of gestation but the higher energy diet did increase fetal weight in the MS breed compared with the lower energy intake diet. These results may be due to differential luteal secretion activity and endometrium gene expression in these two breeds.