Study of the effects of diet supplementation on milk fatty acids composition, rumen bacterial diversity and mammary gland transcriptome in Alpine lactating goats

Aim of this study was to evaluate the effects of diets enriched with polyunsaturated fatty acids (PUFAs), using flax (F) and hempseed (H) supplementation, on milk fatty acid composition, on bacterial diversity in rumen and mammary gene expression of 18 Alpine lactating goats divided into three groups (F, Hand control group C).For this study two time-points were taken into account: at the first time-point(T0), at about 40 DIM, all the goats were fed the same diet; after a week, the diets were differentiated and a second time-point (T1) was fixed at about 150 DIM. At T0 and T1, milk traits were recorded and fatty acid (FA) composition was determined. The concentration of milk fat at T1 increased of almost one percentage point between the animals of F and H groups with respect to C group. Contemporary, RNA-seq was used to study the caprine mammary gland stranscriptome. In total, 12.436 mRNA transcripts, across all the samples, were obtained. Among the three dietary treatment groups, 133 and 491 genes resulted differentially expressed (P<0.05, FDR<0.05) in T1 with respect to T0 in the F and Hgroup, respectively. At these two time points, ruminal fluid samples were also collected and the bacterial DNA extracted analyzed by a metagenomic approach. In the three dietary treatment groups, bacterial community was dominated by Bacteroidetes and Firmicutes. Further integrated analysis of differential gene expression and rumen metagenomics will help identifying the key mechanisms underlying milk composition traits in goat.