Cecal microbiota transplantation:unique influence of cecal microbiota from divergently selected inbred donor lines on cecal microbial profile,serotonergic activity,and aggressive behavior of recipient chickens

Background Accumulating evidence from human trials and rodent studies has indicated that modulation of gut microbiota affects host physiological homeostasis and behavioral characteristics.Similarly,alterations in gut micro-biota could be a feasible strategy for reducing aggressive behavior and improving health in chickens.The study was conducted to determine the effects of early-life cecal microbiota transplantation(CMT)on cecal microbial composi-tion,brain serotonergic activity,and aggressive behavior of recipient chickens.Methods Chicken lines 63 and 72 with nonaggressive and aggressive behavior,respectively,were used as donors and a commercial strain Dekalb XL was used as recipients for CMT.Eighty-four 1-d-old male chicks were randomly assigned to 1 of 3 treatments with 7 cages per treatment and 4 chickens per cage(n=7):saline(control,CTRL),cecal solution of line 6_(3)(6_(3)-CMT),and cecal solution of line 7_(2)(7_(2)-CMT).Transplantation was conducted via oral gavage once daily from d 1 to 10,and then boosted once weekly from week 3 to 5.At weeks 5 and 16,home-cage behavior was recorded,and chickens with similar body weights were assigned to paired aggression tests between the treat-ments.Samples of blood,brain,and cecal content were collected from the post-tested chickens to detect CMT-induced biological and microbiota changes.Results 63-CMT chickens displayed less aggressive behavior with a higher hypothalamic serotonergic activity at week 5.Correspondingly,two amplicon sequence variants(ASVs)belonging to Lachnospiraceae and one Ruminococ-caceae UCG-005 ASV were positively correlated with the levels of brain tryptophan and serotonin,respectively.7_(2)-CMT chickens had lower levels of brain norepinephrine and dopamine at week 5 with higher levels of plasma serotonin and tryptophan at week 16.ASVs belonging to Mollicutes RF39 and GCA-900066225 in 7_(2)-CMT chickens were nega-tively correlated with the brain 5-hydroxyindoleacetic acid(5-HIAA)at week 5,and one Bacteroides ASV was negatively correlated with plasma serotonin at week 16.Conclusion Results indicate that CMT at an early age could regulate aggressive behavior via modulating the cecal microbial composition,together with central serotonergic and catecholaminergic systems in recipient chickens.The selected CMT could be a novel strategy for reducing aggressive behavior through regulating signaling along the microbiota-gut-brain axis.

A behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant,mid-gestation,and late-gestation sows

Background:Although thermal indices have been proposed for swine,none to our knowledge differentiate by reproductive stage or predict thermal comfort using behavioral and physiological data.The study objective was to develop a behavior and physiology-based decision support tool to predict thermal comfort and stress in multiparous(3.28±0.81)non-pregnant(n=11),mid-gestation(n=13),and late-gestation(n=12)sows.Results:Regression analyses were performed using PROC MIXED in SAS 9.4 to determine the optimal environmental indicator[dry bulb temperature(TDB)and dew point]of heat stress(HS)in non-pregnant,mid-gestation,and lategestation sows with respiration rate(RR)and body temperature(TB)successively used as the dependent variable in a cubic function.A linear relationship was observed for skin temperature(T_(S))indicating that TDB rather than the sow HS response impacted T_(S)and so T_(S)was excluded from further analyses.Reproductive stage was significant for all analyses(P<0.05).Heat stress thresholds for each reproductive stage were calculated using the inflections points of RR for mild HS and TB for moderate and severe HS.Mild HS inflection points differed for non-pregnant,mid-gestation,and late gestation sows and occurred at 25.5,25.1,and 24.0℃,respectively.Moderate HS inflection points differed for non-pregnant,mid-gestation,and late gestation sows and occurred at 28.1,27.8,and 25.5℃,respectively.Severe HS inflection points were similar for non-pregnant and mid-gestation sows(32.9℃)but differed for late-gestation sows(30.8℃).These data were integrated with previously collected behavioral thermal preference data to estimate the TDB that non-pregnant,mid-gestation,and late-gestation sows found to be cool(TDB<TDB preference range),comfortable(TDB=TDB preference range),and warm(TDB preference range<TDB<mild HS).Conclusions:The results of this study provide valuable information about thermal comfort and thermal stress thresholds in sows at three reproductive stages.The development of a behavior and physiology-based decision support tool to predict thermal comfort and stress in non-pregnant,mid-gestation,and late-gestation sows is expected to provide swine producers with a more accurate means of managing sow environments.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

Background:The study objective was to test the hypothesis that 1)lowering dietary crude protein(CP)increases dietary energetic efficiency and reduces metabolic heat associated with lactation,and 2)excessive dietary leucine(Leu)supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.Methods:Fifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets(10.80 MJ/kg net energy):1)control(CON;18.75%CP),2)reduced CP with a near ideal or optimal AA profile(OPT;13.75%CP)and 3)diet OPT with excessive Leu(OPTLEU;14.25%CP).Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1,4,8,14,18,and 21 of lactation.Energy balance was measured on sows during early(day 4 to 8)and peak(day 14 to18)lactation,and milk was sampled on day 8 and 18.Results:Over 21-day lactation,sows fed OPT lost body weight and body lipid(P<0.05).In peak lactation,sows fed OPT had higher milk energy output(P<0.05)than CON.Sows fed OPTLEU tended(P=0.07)to have less milk energy output than OPT and did not differ from CON.Maternal energy retention was lower(P<0.05)in OPT and OPTLEU compared to CON sows,and did not differ between OPTLEU and OPT sows.Sows fed OPT had higher(P<0.05)apparent energy efficiency for milk production compared to CON.Heat production associated with lactation was lower(P<0.05)or tended to be lower(P=0.082),respectively,in OPT and OPTLEU compared to CON sows.Conclusion:The OPT diet,in peak lactation,improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss,and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization.Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk,partially explaining the effectiveness of OPT diet over CON diets.

Effect of dietary near ideal amino acid profile on heat production of lactating sows exposed to thermal neutral and heat stress conditions

Background:Reduced protein diet manifested potential to mitigate heat production based on the concept of ideal amino acid profile.The hypothesis of this study was that lactating sows fed a low crude protein(LCP)diet with supplemental amino acid produce less heat compared to those fed a high crude protein(HCP)diet under both thermal neutral(TN)and heat stress(HS)conditions.Methods:Thirty-two lactating sows were allotted to HCP(193 g CP/kg)and LCP(140 g CP/kg)diets under thermal neutral(TN,21±1.5°C)or cycling heat stress(HS,32±1.5°C daytime and 24±1.5°C nighttime)conditions.Diets contained 0.90%SID lysine and 10.8 MJ/kg net energy.Positive pressure indirect calorimeters were used to measure gas exchange in individual sows with litters,and individual piglets on days 4,8,14 and 18.Sow and litter weights were recorded on days 1,10 and 21.Results:Sow total heat production(THP)was calculated by subtracting litter THP from sow+litter THP based on BW0.75.Sow BW and body protein(BP)loss was greater for LCP diet compared to HCP diet in peak lactation(P<0.05 and P<0.01,respectively)and throughout the entire lactation period(P<0.05 and P=0.056,respectively)under HS conditions.Heat-stressed sows fed HCP diet had higher(P<0.05)rectal temperature at 13:00(P<0.05)and 19:00(P<0.01),and higher respiration rate at 07:00(P<0.05),13:00(P<0.05)and 19:00(P<0.05)compared to TN sows fed HCP diet.In sows fed LCP diet,those under HS tended to have higher(P=0.098)rectal temperature at 13:00 and had higher(P<0.05)respiration rate at 07:00,13:00 and 19:00 compared to TN sows.The relationship between daily THP and days in lactation of sows fed LCP diet was quadratic(P<0.05),with an ascending trend until day 14 and a descending trend from days 14 to 18.Sows fed LCP diet had lower daily THP at day 18(P<0.001)compared to those fed the HCP diet under HS conditions.Conclusion:Reduction in THP in sows fed LCP diet was largely associated with THP on day 18 of lactation under HS conditions.Feeding LCP diets alleviated the increased body temperature in sows under HS conditions throughout lactation,which was accompanied by a reduction in respiration rate.Total heat production is associated with days in lactation,in particular under HS conditions with THP appearing to peak between days 14 and 18.