Impact of dietary fat levels and fatty acid composition on milk fat synthesis in sows at peak lactation

Background Dietary fat is important for energy provision and immune function of lactating sows and their progeny.However,knowledge on the impact of fat on mammary transcription of lipogenic genes,de novo fat synthesis,and milk fatty acid(FA)output is sparse in sows.This study aimed to evaluate impacts of dietary fat levels and FA composition on these traits in sows.Forty second-parity sows(Danish Landrace×Yorkshire)were assigned to 1 of 5 dietary treatments from d 108 of gestation until weaning(d 28 of lactation):low-fat control diet(3%added animal fat);or 1 of 4 high-fat diets with 8%added fat:coconut oil(CO),fish oil(FO),sunflower oil(SO),or 4%octanoic acid plus 4%FO(OFO).Three approaches were taken to estimate de novo milk fat synthesis from glucose and body fat.Results Daily intake of FA was lowest in low-fat sows within fat levels(P<0.01)and in OFO and FO sows within highfat diets(P<0.01).Daily milk outputs of fat,FA,energy,and FA-derived carbon reflected to a large extent the intake of those.On average,estimates for de novo fat synthesis were 82 or 194 g/d from glucose according to method 1 or 2 and 255 g de novo+mobilized FA/d according to method 3.The low-fat diet increased mammary FAS expression(P<0.05)and de novo fat synthesis(method 1;P=0.13)within fat levels.The OFO diet increased de novo fat synthesis(method 1;P<0.05)and numerically upregulated mammary FAS expression compared to the other high-fat diets.Across diets,a daily intake of 440 g digestible FA minimized milk fat originating from glucose and mobilized body fat.Conclusions Sows fed diets with low-fat or octanoic acid,through upregulating FAS expression,increased mammary de novo fat synthesis whereas the milk FA output remained low in sows fed the low-fat diet or high-fat OFO or FO diets,indicating that dietary FA intake,dietary fat level,and body fat mobilization in concert determine de novo fat synthesis,amount and profiles of FA in milk.

Supplementation of a lacto-fermented rapeseed-seaweed blend promotes gut microbial-and gut immune-modulation in weaner piglets

Background:The direct use of medical zinc oxide in feed will be abandoned after 2022 in Europe,leaving an urgent need for substitutes to prevent post-weaning disorders.Results:This study investigated the effect of using rapeseed-seaweed blend(rapeseed meal added two brown macroalgae species Ascophylum nodosum and Saccharina latissima)fermented by lactobacilli(FRS)as feed ingredients in piglet weaning.From d 28 of life to d 85,the piglets were fed one of three different feeding regimens(n=230 each)with inclusion of 0%,2.5% and 5% FRS.In this period,no significant difference of piglet performance was found among the three groups.From a subset of piglets(n=10 from each treatment),blood samples for hematology,biochemistry and immunoglobulin analysis,colon digesta for microbiome analysis,and jejunum and colon tissues for histopathological analyses were collected.The piglets fed with 2.5% FRS manifested alleviated intraepithelial and stromal lymphocytes infiltration in the gut,enhanced colon mucosa barrier relative to the 0% FRS group.The colon microbiota composition was determined using V3 and V1-V8 region 16S rRNA gene amplicon sequencing by Illumina NextSeq and Oxford Nanopore MinION,respectively.The two amplicon sequencing strategies showed high consistency between the detected bacteria.Both sequencing strategies indicated that inclusion of FRS reshaped the colon microbiome of weaned piglets with increased Shannon diversity.Prevotella stercorea was verified by both methods to be more abundant in the piglets supplied with FRS feed,and its abundance was positively correlated with colonic mucosa thickness but negatively correlated with blood concentrations of leucocytes and IgG.Conclusions:FRS supplementation relieved the gut lymphocyte infiltration of the weaned piglets,improved the colon mucosa barrier with altered microbiota composition.Increasing the dietary inclusion of FRS from 2.5% to 5% did not lead to further improvements.

Impacts of prenatal nutrition on animal production and performance： a focus on growth and metabolic and endocrine function in sheep

The concept of foetal programming（FP） originated from human epidemiological studies, where foetal life nutrition was linked to health and disease status later in life. Since the proposal of this phenomenon, it has been evaluated in various animal models to gain further insights into the mechanisms underlying the foetal origins of health and disease in humans. In FP research, the sheep has been quite extensively used as a model for humans. In this paper we will review findings mainly from our Copenhagen sheep model, on the implications of late gestation malnutrition for growth, development, and metabolic and endocrine functions later in life, and discuss how these implications may depend on the diet fed to the animal in early postnatal life. Our results have indicated that negative implications of foetal malnutrition, both as a result of overnutrition and, particularly, late gestation undernutrition, can impair a wide range of endocrine functions regulating growth and presumably also reproductive traits. These implications are not readily observable early in postnatal life, but are increasingly manifested as the animal approaches adulthood. No intervention or cure is known that can reverse this programming in postnatal life. Our findings suggest that close to normal growth and slaughter results can be obtained at least until puberty in animals which have undergone adverse programming in foetal life, but manifestation of programming effects becomes increasingly evident in adult animals.Due to the risk of transfer of the adverse programming effects to future generations, it is therefore recommended that animals that are suspected to have undergone adverse FP are not used for reproduction. Unfortunately, no reliable biomarkers have as yet been identified that allow accurate identification of adversely programmed offspring at birth,except for very low or high birth weights, and, in pigs, characteristic changes in head shape（dolphin head）. Future efforts should be therefore dedicated to identify reliable biomarkers and evaluate their effectiveness for alleviation/reversal of the adverse programming in postnatal life. Our sheep studies have shown that the adverse impacts of an extreme, high-fat diet in early postnatal life, but not prenatal undernutrition, can be largely reversed by dietary correction later in life. Thus, birth（at term） appears to be a critical set point for permanent programming in animals born precocial,such as sheep. Appropriate attention to the nutrition of the late pregnant dam should therefore be a priority in animal production systems.