Serum and milk folates during the first two gestations and lactations in Romanov, Finnsheep, and Suffolk ewes

Serum concentrations of folic acid and cobalamin and energy metabolism of ewes as a function of the energy density of the diet, peripartum period, and pregnancy toxemia

The aim of this study was to determine the serum levels of folic acid, cobalamin, and indicators of energy metabolism during the peripartum period of ewes submitted to different diets and with or without pregnancy toxemia. Forty Santa Inês ewes were divided into three groups, a group of 20 animals fed only roughage-diet with low energy density (G1), a group of 10 ewes submitted to diet containing roughage and concentrate-diet with high energy density (G2), and a group of 10 ewes with diagnosis of pregnancy toxemia (PT) (G3). In the ewes of groups G1 and G2, blood samples were collected -30, -15, -7 days pre-partum, on the day of partum, and 7, 15, and 30 days postpartum; blood samples from G3 animals were collected during the veterinary clinic care. Significant variations were observed in the plasma concentration of glucose and serum folic acid, cobalamin, fructosamine, NEFA, and β-hydroxybutyrate in the groups fed diets with different energy levels, with and without PT (P < 0.05). A positive correlation of folic acid and cobalamin was observed with plasma glucose and serum NEFA concentrations, in addition to negative correlation of glucose with NEFA and β-hydroxybutyrate and positive correlation between the latter biomarkers of energy metabolism. The ewes diagnosed with PT showed higher levels of folic acid, NEFA, and β-hydroxybutyrate (P < 0.05). Ewes fed diet containing roughage and concentrate present higher serum levels of folic acid, cobalamin, and glucose, in the pre-partum period and in the lactation period. The results obtained contribute to better understanding of the application of blood concentration tests for folic acid and cobalamin in the energy metabolism and in PT in ewes.

Genome-wide association study and pathway analysis identify NTRK2 as a novel candidate gene for litter size in sheep

Litter size is one of the most important economic traits in sheep. Identification of gene variants that are associated with the prolificacy rate is an important step in breeding program success and profitability of the farm. So, to identify genetic mechanisms underlying the variation in litter size in Iranian Baluchi sheep, a two-step genome-wide association study (GWAS) was performed. GWAS was conducted using genotype data from 91 Baluchi sheep. Estimated breeding values (EBVs) for litter size calculated for 3848 ewes and then used as the response variable. Besides, a pathway analysis using GO and KEGG databases were applied as a complementary approach. A total of three single nucleotide polymorphisms (SNPs) associated with litter size were identified, one each on OAR2, OAR10, and OAR25. The SNP on OAR2 is located within a novel putative candidate gene, Neurotrophic receptor tyrosine kinase 2. This gene product works as a receptor which is essential for follicular assembly, early follicular growth, and oocyte survival. The SNP on OAR25 is located within RAB4A which is involved in blood vessel formation and proliferation through angiogenesis. The SNP on OAR10 was not associated with any gene in the 1Mb span. Moreover, gene-set analysis using the KEGG database identified several pathways, such as Ovarian steroidogenesis, Steroid hormone biosynthesis, Calcium signaling pathway, and Chemokine signaling. Also, pathway analysis using the GO database revealed several functional terms, such as cellular carbohydrate metabolic, biological adhesion, cell adhesion, cell junction, and cell-cell adherens junction, among others. This is the first study that reports the NTRK2 gene affecting litter size in sheep and our study of this gene functions showed that this gene could be a good candidate for further analysis.

Maternal Folic Acid Supplementation Differently Affects the Small Intestinal Phenotype and Gene Expression of Newborn Lambs from Differing Litter Sizes

The purpose of this study was to investigate the effect of maternal dietary folic acid (FA) supplementation during gestation on small intestinal development of newborn lambs of different litter sizes, focusing on the intestinal morphology and development-, apoptosis- and digestion-related genes expression. One hundred and twenty Hu ewes (Ovis aries) were inseminated and randomly allotted to three groups. One group received a control diet [without FA supplementation, control (CON)] and the other two groups received control diets supplemented with different amount of FA [16 or 32 mg FA per kg dry matter (DM), i.e., F16 and F32] during pregnancy. After lambing, according to the dietary FA levels and litter size (twins, TW; triplets, TR), the neonatal lambs were divided into 6 (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) treatment groups. The results showed that the ratio of small intestinal weight to live body weight and the thickness of the intestinal muscle layer in the offspring was enhanced significantly with increasing maternal FA supplementation (p < 0.05). Meanwhile, the expression levels of insulin-like growth factor I (IGF-I), B-cell lymphoma-2 (BCL-2) and sodium/glucose co-transporter-1 (SGLT1) in the small intestines of the newborn lambs were increased, while the opposite was true for Bcl2-associated × (BAX) in response to FA supplementation (p < 0.05). Moreover, the small intestinal weights of twins were significantly higher than those of triplets (p < 0.01), and the expression levels of IGF-I (p < 0.05), sucrase-isomaltase (SI) (p < 0.05) and solute carrier family 2 member 5 (SLC2A5) (p < 0.01) were significantly lower than those in triplets. These findings suggest that maternal FA supplementation could improve the offspring's small intestinal phenotype and the expression of development-, apoptosis- and digestion-related genes, so it could promote the small intestinal development of newborn lambs. Furthermore, the small intestine phenotypic development of twins was generally better than that of triplets, while the expression levels of the above genes of twins were lower than those of triplets.

Effect of Dietary Folic Acid Supplementation during Pregnancy on Blood Characteristics and Milk Composition of Ewes

The objective of the present study was to investigate the dynamic change of serum parameters and milk composition by dietary FA supplementation with ewes with different litter size from mating to lambing. The ewes were divided into six treatments (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) according to dietary FA levels (control, CON; 16 or 32 mg·kg^-1 rumen-protect-FA supplementation, F16 and F32) and litter size (twin born, TW; and triplet born, TR). In serum, the concentration of folate increased linearly with dietary FA supplementation (P < 0.05), regardless of the litter size, they showed a quadratic response to gestation progression (P < 0.05). With dietary FA addition, IGFI-I levels significant increased from late gestation to after lambing (P < 0.05), and linearly increased immunoglobulin during the perinatal period (P < 0.05). In colostrum and milk at d 15, the content of folate, lactoferrin, and IgG were affected positively by FA supplementation (P < 0.05). IgG was higher in the TW group than TR in colostrum (P < 0.05), and lactoferrin in TW was lower than TR in milk of d 15 (P < 0.05). FA supplementation increased protein content in colostrum (P < 0.05), while it had no effect on the fat, lactose, and BUN of colostrum and milk of d 15 (P > 0.05). These results suggest that FA supplementation during gestation could regulate maternal blood metabolism and contribute to milk immune composition.

Maternal folic acid supplementation modulates the growth performance, muscle development and immunity of Hu sheep offspring of different litter size

It is generally accepted that the phenotype and gene expression pattern of the offspring can be altered by maternal folic acid (FA) supplementation during the gestation period. The aims of this study were to investigate the effects of maternal FA supplementation on the growth performance, muscle development and immunity of newborn lambs of different litter size. According to litter size (twins, TW; triplets, TR) and maternal dietary FA supplementation levels (control, C; 16 or 32 mg·kg^-1 FA supplementation, F16 and F32), neonatal lambs were randomly divided into six groups (TW-C, TW-F16, TW-F32, TR-C, TR-F16 and TR-F32). After farrowing, the birth weight in TW was higher than that in the TR group, and increased with FA supplementation of their mothers (P<.05). Folate, IGF-I, IgM and IgA concentrations of newborn lambs showed a litter size and FA supplementation interaction (P<.05). FA supplementation also increased diameter, area, perimeter and DNA content of the longissimus dorsi muscle of the lambs (P<.05) regardless of the litter size. Transcriptome analysis of the longissimus dorsi muscle revealed differentially expressed genes with dietary FA supplementation enriched in immunity- and cell development-related genes. Furthermore, FA supplementation upregulated the expression of myogenesis-related genes, while downregulated those involved in the inhibition of muscle development. In addition, immunity-related genes in the neonatal lambs showed lower expression levels in response to maternal dietary FA supplementation. Overall, maternal FA supplementation during gestation could increase the offspring's birth weight and modulate its muscle development and immunity.

Influence of folic acid supplements on the carry-over of folates from the sow to the piglet

This experiment aimed to investigate the influence of folic acid supplements on the carry-over of folates from the sow to the fetus during late gestation and to the suckling piglet. Two groups of sixteen German Landrace sows received, during gestation and lactation, a diet supplemented with either 0 or 10 mg folic acid/kg. Increased folic acid concentrations in the serum of sows were detected only at the end of gestation (day 100) and at the end of lactation (day 28). The supplementation with folic acid to the sows' diet improved the folic acid supply of the fetus compared with unsupplemented controls; values were respectively 92.6 v. 56.2 nmol folates/l serum in newborn piglets and 171.9 v. 76.3 micromol folates/g fresh liver in stillborn piglets (P < 0.05). Folate concentrations in colostrum and milk (day 28) were 3.6- and 5.0-times higher in supplemented than unsupplemented sows. This treatment effect was also reflected in the serum of piglets until weaning. Therefore, the folic acid supply for the suckling piglet is dependent mainly upon the carry-over of maternal folates via colostrum and milk.

Effect of insulin on feed intake and reproductive performance of well-nourished nulliparous ewes

Eighty-four nulliparous ewes were used to examine the effect of short-term insulin treatment on feed intake and reproductive performance. Following estrus synchronization, ewes were observed for estrus (= Day 0) and were penned individually beginning on Day 7. Ewes were fed twice daily and feed intake was recorded. On Days 9 through 13, ewes were treated s.c. with 1 IU/kg BW insulin (n = 44) or an equivalent volume of saline (n = 40). On Day 14, ewes were placed with fertile rams and number of ewes in estrus (bred) was recorded. Thirty days post-breeding, ewes were checked for pregnancy via ultrasonography. Feed intake and percentage of ewes in estrus did not differ between saline- and insulin-treated ewes. Similarly, neither pregnancy rate (69 +/- 8.7% vs. 80 +/- 8.1%, respectively) nor lambing rate (61 +/- 8.9% vs. 78 +/- 8.4%, respectively) differed between treatments. The number of lambs born per ewe was, however influenced by a breed-group effect (P < 0.0002). Romanov ewes had more (P < 0.001) lambs than the other breed groups in the study. Therefore, treating well-nourished, nulliparous ewe lambs with insulin did not increase reproductive efficiency, possibly because the ewes were already at a maximal nutritional and/or reproductive state.