Early Lactation Period Research Articles

Altered antioxidant enzymes activity in csa-treated HepG2 cells in the presence of vitamin E and in the combination with quercetin

Greater metabolic demands in high-producing dairy cows are believed to be a cause of sub-fertility in these animals. Previously, supplementation with vitamin B complex molecules has shown benefits in improving milk production, health, and reproductive efficiency of dairy cows. The primary aim of this project was to determine the effects of rumen-protected vitamin B complex supplementation of 100 g of Transition VB (Jefo, St. Hyacinthe, QC, Canada) and 4 g of Lactation VB (VB; Jefo), during the transition and early lactation periods, respectively, compared with a control diet containing no supplementation on d 14 endometrial outcomes of pregnancy. In the vitamin B supplemented cows, we expect to see a change in the mark-up of endometrial genes important for embryo survival before implantation. Multiparous Holstein cows were enrolled into the study 3 wk before parturition and were randomly assigned to either the VB or control treatment. Twice-a-week blood samples, weekly milk samples, and daily feed intake were collected. Cows were enrolled onto a double-ovsynch protocol at 33 ± 3 d postpartum and inseminated by timed artificial insemination. Milk production and components, concentrations of BHB, haptoglobin, and progesterone in serum, and ovarian dynamics were also measured, but no treatment effect was observed. The uterus was flushed on d 14 after artificial insemination (around 72 DIM) for conceptus collection, and endometrial samples were collected at the same time. Overall, 42 cows were flushed and 13 embryos were collected. Analysis of mRNA expression of genes related to embryo development, immune system, adhesion, and regulation of vitamin B molecules showed that OXTR, MUC5B, MUC1, IL1B, SPP, TRD, FZD8, and FOLR1 genes were significantly upregulated in the VB group. Vitamin B supplementation had no effect on the size of the embryo and ovulatory follicle or corpus luteum diameter at embryo collection. In conclusion, the benefits of strategic dietary VB supplementation during the transition and early lactation might be directly linked to endometrial functions required for embryo survival during the peri-implantation period.

Functional analysis of the dairy cow mammary transcriptome between early lactation and mid-dry period.

In this research communication we used digital gene expression (DGE) analysis to identify differences in gene expression in the mammary glands of dairy cows between early lactation and the mid-dry period. A total of 741 genes were identified as being differentially expressed by DGE analysis. Compared with their expression in dry cows, 214 genes were up-regulated and 527 genes were down-regulated in lactating cow mammary glands. Gene Ontology analysis showed that lactation was supported by increased gene expression related to metabolic processes and nutrient transport and was associated with decreased gene expression related to cell proliferation. Pathway mapping using the Kyoto Encyclopedia of Genes and Genomes showed that 579 differentially expressed genes had pathway annotations related to 204 pathways. Metabolic pathway-related genes were the most significantly enriched. Genes and pathways identified by the present study provide insights into molecular events that occur in the mammary gland between early lactation and mid-dry period, which can be used to facilitate further investigation of the mechanisms underlying lactation and mammary tissue remodeling in dairy cows.

Increasing metabolisable energy and protein supplementation to stimulate the subsequent milk production during late gestation by increasing proliferation and reducing apoptosis in goat mammary gland prepartum

In total, 32 pregnant goats were assigned randomly to four diets fed from Day 100 of pregnancy to Day 30 after parturition, to determine the effects of metabolisable energy (ME) and metabolisable protein (MP) supplementation levels on feed intake, subsequent colostrum and milk production and expression of genes regulating mammary-cell proliferation and apoptosis. Diets were as follows: (1) diet with ME and MP provided according to NRC recommendations (control), (2) diet with extra 10% ME, (3) diet with extra 10% MP, and (4) diet 1 with 10% extra of both ME and MP. Mammary biopsies were obtained from each udder half 24 h after parturition. Feed intake (g/day), and colostrum (kg/day) and milk (kg/month) production increased when the extra ME and MP were provided together prepartum and in early lactation (P < 0.05). Relative mRNA expressions significantly increased in the mammary gland of insulin-like growth factor 1 (IGF-1, 4.3-fold), IGF-1 receptor (IGF-1R, 3.6-fold) and B-cell lymphoma 2 (Bcl-2, 4.6-fold), whereas insulin-like growth factor binding protein 3 (IGFBP-3, 3.2-fold), Bcl-2-associated X protein (Bax, 16.7-fold) and the ratio of Bax:Bcl-2 expressions significantly decreased (69.8-fold) with increased ME and MP levels fed in late gestation. In conclusion, colostrum production and milk yield in the early lactation period are sensitive to nutrient supply during gestation, where increased dietary ME as well as MP supplementation levels during late gestation will favour mammary development, by increasing expression of genes stimulating cellular proliferation (IGF-1, IGF-1R, Bcl-2) and reduced those stimulating apoptosis (IGFBP-3, Bax).

Variance heterogeneity and genotype by environment interactions in native Black and White dual-purpose cattle for different herd allocation schemes

Black and White dual-purpose cattle (DSN) are kept in diverse production systems, but the same set of genetic parameters is used for official national genetic evaluations, neglecting the herd or production system characteristics. The aim of the present study was to infer genetic (co)variance components within and across defined herd descriptor groups or clusters, considering only herds keeping the local and endangered DSN breed. The study considered 3659 DSN and 2324 Holstein Friesian (HF) cows from parities one to three. The 46 herds always kept DSN cows, but in most cases, herds were ‘mixed’ herds (Mixed), including both genetic lines HF and DSN. In order to study environmental sensitivity, we had a focus on the naturally occurring negative energy balance in the early lactation period. In consequence, traits were records from the 1st official test-day after calving for milk yield (Milk-kg), somatic cell score (SCS) and fat-to-protein ratio (FPR). Genetic parameters were estimated in bivariate runs (separate runs for the three genetic lines Mixed, HF and DSN), defining the same trait from different herd groups or clusters as different traits. Additive-genetic variances and heritabilities were larger in herd groups that indicated superior herd management, implying that cow records from these herds allow a better genetic differentiation. Superior herd management included larger herds, low calving age, high herd production levels and low intra-herd somatic cell count. Herd descriptor group differences in additive-genetic variances for Milk-kg were stronger in HF than in DSN, indicating environmental sensitivity for DSN. Similar variance components and heritabilities across groups, clusters and genetic lines were found for data stratification according to geographical descriptors altitude and latitude. Considering 72 bivariate herd group runs, 29 genetic correlations were very close to 1 (mostly for Milk-kg). Somatic cell score was the trait showing the smallest genetic correlations, especially in the DSN analyses, and when stratifying herds according to genetic line compositions (rg=0.11), or according to the percentage of natural service sires (rg=0.08). For estimations based on the results of a cluster analysis considering several herd descriptors simultaneously, indications for genotype × environment interactions could be found for SCS, but genetic correlations were larger than 0.80 for Milk-kg and FPR. In conclusion, we suggest multiple-trait animal model applications in genetic evaluations, in order to select the best sires for specific herd environments or herd clusters.

AVALIAÇÃO DO PERÍODO PERIPARTO POR PARÂMETROS CLÍNICOS E HEMATOLÓGICOS EM CABRAS LEITEIRAS

Resumo O objetivo deste trabalho foi avaliar o efeito do período de periparto sobre os parâmetros clínicos e hematológicos de cabras adultas. Utilizou-se animais da raça Saanen e Parda Alpina, sendo 24 nos tempos: T-15 (quinze dias antes do parto), T0 (imediatamente após o parto), T2 (dois dias após o parto), T5 (cinco dias após o parto), T10 (dez dias após o parto), T15 (quinze dias após o parto) e T30 (trinta dias após o parto) e 10 animais como grupo controle (Mesma raça, não gestantes e não lactantes). Como principais achados físicos, observou-se que a frequência cardíaca (FC) dos animais é normalmente mais elevada no pré-parto e parto, caindo ao longo do tempo de lactação. A frequência respiratória (FR) dos animais avaliados é mais elevada em relação aos animais controle, com o pico acontecendo no T-15. Na avaliação das principais observações no hemograma, observam-se valores mais baixos para hemoglobina no T-15 em relação ao grupo controle, e uma redução da toda série vermelha no T15. Houve uma elevação do número de leucócitos por neutrofilia com linfopenia em T0 e a leucocitose com neutrofilia se manteve ao longo da fase observacional. Valores de proteínas mais baixos foram observados em T-15 e T0, aumentando posteriormente. A variável fibrinogênio apresentou o maior valor em T0. Conclui-se que os parâmetros físicos e hematimétricos são úteis para detecção das variações que ocorrem no periparto. Tais achados, associados ao leucograma de estresse e aumento da taxa metabólica basal, encontrado nesta mesma fase, corroboram com o momento de fragilidade fisiológica na qual a cabra se encontra. Assim, cuidados no manejo relacionados ao conforto térmico e atendimento às exigências nutricionais são fundamentais a fim de se evitar mais desequilíbrios orgânicos decorrentes de fatores externos que podem vir a comprometer a saúde do caprino e posterior desempenho produtivo.

Diagnosis of subclinical ketosis in dairy cows

Ketosis is a common disease in high producing dairy cows during the early lactation period. Subclinical ketosis (SCK) and periparturient diseases considerably account for economic and welfare losses in dairy cows. Subclinical ketosis poses an increased risk of production-related diseases such as clinical ketosis, displaced abomasum, retained placenta, lameness, mastitis and metritis. Production efficiency decreases (lower milk production, poor fertility, and increased culling rates), which results in economic losses. Increased concentrations of circulating ketone bodies, predominantly ?-hydroxybutyrate (BHB), without the presence of clinical signs of ketosis are considered as SCK. It is characterized by increased levels of ketone bodies in the blood, urine and milk. The gold standard test for ketosis is blood BHB. This ketone body is more stable in blood than acetone or acetoacetate. The most commonly used cut-points for subclinical ketosis are 1.2 mmol/L or 1.4 mmol/L for BHB in the blood. Clinical ketosis generally involves much higher levels of BHB, about 3.0 mmol/L or more. Usually, detection of SCK is carried out by testing ketone body concentrations in blood, urine and milk. A variety of laboratory and cowside tests are available for monitoring ketosis in dairy herds. But no cowside test has perfect sensitivity and specificity compared to blood BHB as the gold standard test. The aim of this review is to overview diagnostic tests for SCK in dairy cows, including laboratory and cowside tests.

Influence of feeding with live yeast on cow productivity and milk quality

Influence of feeding with live yeast on cow productivity and milk quality

Rumen-protected B vitamin complex supplementation during the transition period and early lactation alters endometrium mRNA expression on day 14 of gestation in lactating dairy cows

Greater metabolic demands in high-producing dairy cows are believed to be a cause of sub-fertility in these animals. Previously, supplementation with vitamin B complex molecules has shown benefits in improving milk production, health, and reproductive efficiency of dairy cows. The primary aim of this project was to determine the effects of rumen-protected vitamin B complex supplementation of 100 g of Transition VB (Jefo, St. Hyacinthe, QC, Canada) and 4 g of Lactation VB (VB; Jefo), during the transition and early lactation periods, respectively, compared with a control diet containing no supplementation on d 14 endometrial outcomes of pregnancy. In the vitamin B supplemented cows, we expect to see a change in the mark-up of endometrial genes important for embryo survival before implantation. Multiparous Holstein cows were enrolled into the study 3 wk before parturition and were randomly assigned to either the VB or control treatment. Twice-a-week blood samples, weekly milk samples, and daily feed intake were collected. Cows were enrolled onto a double-ovsynch protocol at 33 ± 3 d postpartum and inseminated by timed artificial insemination. Milk production and components, concentrations of BHB, haptoglobin, and progesterone in serum, and ovarian dynamics were also measured, but no treatment effect was observed. The uterus was flushed on d 14 after artificial insemination (around 72 DIM) for conceptus collection, and endometrial samples were collected at the same time. Overall, 42 cows were flushed and 13 embryos were collected. Analysis of mRNA expression of genes related to embryo development, immune system, adhesion, and regulation of vitamin B molecules showed that OXTR, MUC5B, MUC1, IL1B, SPP, TRD, FZD8, and FOLR1 genes were significantly upregulated in the VB group. Vitamin B supplementation had no effect on the size of the embryo and ovulatory follicle or corpus luteum diameter at embryo collection. In conclusion, the benefits of strategic dietary VB supplementation during the transition and early lactation might be directly linked to endometrial functions required for embryo survival during the peri-implantation period.

PSXI-8 Supplementation of a fennel herbaceous flavor to total mixed rations containing cottonseed or flaxseed increased dry matter intake of high-yield Holstein cows during early lactation period.

PSXI-8 Supplementation of a fennel herbaceous flavor to total mixed rations containing cottonseed or flaxseed increased dry matter intake of high-yield Holstein cows during early lactation period.

PSXII-12 Dietary flavors and rumen bioactive additives increased feed intake and lactation performance of high-yield Holstein cows during early lactation period.

PSXII-12 Dietary flavors and rumen bioactive additives increased feed intake and lactation performance of high-yield Holstein cows during early lactation period.

The dynamics of individual whey protein concentrations in cows' mammary secretions during the colostral and early lactation periods.

The bovine whey consists of more than 200 different types of proteins, of which β-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulins and lactoferrin predominate. However, their concentrations are not stable due to the existence of protein dynamics during a transition from colostrum secretion to mature milk. To evaluate the dynamics of whey proteins of Jersey cows during a colostral phase and first month of lactation and an influence of the number of lactations, 268 milk samples from 135 Jersey cows were selected through a clinical evaluation. Whey was obtained by rennet coagulation of the mammary secretion. The concentration of total proteins was determined by the biuret method and their fractions were identified by 12% dodecyl sulfate-polyacrylamide gel electrophoresis (12% SDS-PAGE). Maximum concentrations of all protein fractions were observed in the first 12 h of lactation, reducing over the course of the study. Modification of the protein predominance was also observed. The transition from colostrum secretion to milk occurred between 24 and 72 h postpartum. There was an influence of the number of lactations on the dynamics of whey proteins, indicating that multiparous cows had better immunological and nutritional quality when compared to primiparous cows.

115 Exosome-mediated microRNA expression profile in follicular fluid of metabolically divergent postpartum cows

Most high-milking cows enter a state of negative energy balance during the early lactation period. This phenomenon disturbs the metabolic status of the follicular fluid microenvironment, resulting in delayed ovulation. Cell-to-cell communication between the oocyte and the surrounding cells is crucial during folliculogenesis. Exosomes, evolutionarily conserved cargo molecules (30-150nm in diameter) carrying RNA and proteins, are known to be involved in cell-to-cell communication. Here, we aimed to investigate the association between postpartum metabolic status and the expression of exosomal microRNA (miRNA) in follicular fluid of Holstein-Friesian cows. For this, follicular fluid was collected from antral follicles (>8mm in diameter) using ovum pickup procedure from cows (n=30) on a weekly basis between weeks 5 and 10 postpartum. Follicular fluid collected from heifers (n=8) was used as a control. The energy status of each cow was assessed based on the blood metabolite (nonesterified fatty acids and β-hydroxybutyrate) concentration, body weight curve, and overall energy balance determined by dry matter intake. Afterwards, cows were categorized as early negative and late positive (cows show negative energy balance at early weeks and recovered at late weeks postpartum), always negative (cows did not recover until 15 weeks postpartum), and always positive (cows did not enter in to a state of negative energy balance). Following this, exosomes were isolated from pooled samples from each animal category using ultracentrifugation, and their morphology and size was characterised using electron microscopy and nanosight, respectively. Exosomal total RNA enriched with miRNA was isolated using an exosomal RNA isolation kit. Next-generation sequencing of miRNA was performed using Illumina NextSEqn 500 (Illumina Inc., San Diego, CA, USA). MicroRNAs with a fold change ≥2, P-value <0.05, and a false discovery rate of <0.1 were considered differentially expressed. The results showed that a total of 356 known and 156 novel miRNA were identified across samples. Differential expression analysis of miRNA between always-negative cows versus always-positive cows revealed down-regulation of all 6 differentially expressed miRNA, including bta-miR-451, bta-miR-132, and bta-miR-2285. Similarly, down-regulation of 14 miRNA, including bta-miR-20b, bta-miR-363, bta-miR-132, and bta-miR-451, and up-regulation of 3 miRNA was observed in always-negative cows compared to heifers. Furthermore, the target prediction analysis of the down-regulated miRNA have been shown to be involved in regulating different pathways including transforming growth factor-β signalling, cell cycle, hippo signalling, forkhead box O signalling, and endometrial cancer, among others. In conclusion, the results revealed that although negative energy balance in postpartum dairy cows suppressed exosomal miRNA expression in follicular fluid, the opposite was observed in metabolically unstressed cows. This divergence of exosome-mediated miRNA expression in the follicular fluid of metabolically stressed cows could be associated with the reduced fertility of those cows.

Milk microbiome diversity and bacterial group prevalence in a comparison between healthy Holstein Friesian and Rendena cows.

Dry and early lactation periods represent the most critical phases for udder health in cattle, especially in highly productive breeds, such as the Holstein Friesian (HF). On the other hand, some autochthonous cattle breeds, such as the Rendena (REN), have a lower prevalence of mastitis and other transition-related diseases. In this study, milk microbiota of 6 HF and 3 REN cows, all raised on the same farm under the same conditions, was compared. A special focus was placed on the transition period to define bacterial groups’ prevalence with a plausible effect on mammary gland health. Four time points (dry-off, 1 d, 7–10 d and 30 d after calving) were considered. Through 16S rRNA sequencing, we characterized the microbiota composition for 117 out of the 144 milk samples initially collected, keeping only the healthy quarters, in order to focus on physiological microbiome changes and avoid shifts due to suspected diseases. Microbial populations were very different in the two breeds along all the time points, with REN milk showing a significantly lower microbial biodiversity. The taxonomic profiles of both cosmopolitan and local breeds were dominated by Firmicutes, mostly represented by the Streptococcus genus, although in very different proportions (HF 27.5%, REN 68.6%). Large differences in HF and REN cows were, also, evident from the metabolic predictive analysis from microbiome data. Finally, only HF milk displayed significant changes in the microbial composition along the transition period, while REN maintained a more stable microbiota. In conclusion, in addition to the influence on the final characteristics of dairy products obtained from milk of the two breeds, differences in the milk microbiome might, also, have an impact on their mammary gland health.

The Effect of Peroral Administration of Lactobacillus Fermentum Culture on Dairy Cows Health Indices

Abstract The culture of Lactobacillus fermentum was isolated from the biogas substrate. The aim was to evaluate the efficiency of perorally applied L. fermentum additive to prevent metabolic diseases in the early lactation period of dairy cows. The experiment was performed in the early lactation group of a herd with 240 cows. The control and experimental group each consisted of 10 clinically healthy cows with normal concentration of β-hydroxybutyrate and glucose. On day 1–5 (D1–D5), the experimental cows received orally 150 ml of L. fermentum product of 8.1x105 CFU/ml. On D1, D2, D5 and D20, the rumen fluid samples were collected from all animals in both groups with an oral-ruminal probe once per day for detection of pH and concentration of volatile fatty acids, on D1, D5 and D20 – blood samples for biochemical analyses. The data were analyzed using Microsoft Excel. Results: Significant changes were observed in the concentration of the liver enzymes AST and GGT. On D1, in the experimental animals AST concentration 100.5±14.0 IU/L was higher than in control cows – 51.4±5.7 IU/L (p<0.05). On D20, AST was reduced significantly only in experimental cows. On D1, GGT concentration 31.5±6.91 IU/L was higher (p<0.05) in experimental animals than in control cows – 13.6±1.53 IU/L, but on D5, GGT concentration in experimental animals was reduced to 18.4±6.41 IU/L (p<0.05), and remained until D20. Conclusion: L. fermentum culture administered orally for five days improved the blood liver enzymes in cows, and the effect lasted for two weeks.

The contribution of hormone sensitive lipase to adipose tissue lipolysis and its regulation by insulin in periparturient dairy cows

Hormone sensitive lipase (HSL) activation is part of the metabolic adaptations to the negative energy balance common to the mammalian periparturient period. This study determined HSL contribution to adipose tissue (AT) lipolysis and how insulin regulates its activity in periparturient dairy cows. Subcutaneous AT (SCAT) samples were collected at 11 d prepartum (dry) and 11 (fresh) and 24 d (lactation) postpartum. Basal and stimulated lipolysis (ISO) responses were determined using explant cultures. HSL contribution to lipolysis was assessed using an HSL inhibitor (CAY). Basal lipolysis was higher in SCAT at dry compared with fresh. CAY inhibited basal lipolysis negligibly at dry, but at fresh and lactation it reduced basal lipolysis by 36.1 ± 4.51% and 43.1 ± 4.83%, respectively. Insulin inhibited lipolysis more pronouncedly in dry compared to fresh. Results demonstrate that HSL contribution to basal lipolysis is negligible prepartum. However, HSL is a major driver of SCAT lipolytic responses postpartum. Lower basal lipolysis postpartum suggests that reduced lipogenesis is an important contributor to fatty acid release from SCAT. Loss of adipocyte sensitivity to the antilipolytic action of insulin develops in the early lactation period and supports a state of insulin resistance in AT of cows during the first month postpartum.

Characterization of progesterone profile, physiological responses, milk composition and blood biochemical and hematological indices at the early stage of lactation in goats

ABSTRACTThe aim of this research was to describe the progesterone profile, physiological response, milk composition, and blood chemistry at the early stage (DIM 30-90 days) of lactation (E1:30-50; E2:50-70; E3:70-90 days) in Baladi goats under Egyptian conditions. The serum progesterone level was significantly reduced with the progress of the early lactation period to reach the least concentration (0.24 ng/ml) at the E3 stage of lactation (P=0.001). The daily milk yield was significantly increased with the progress of the lactation to reach the peak at the E2 stage of lactation (P=0.015). The percentage of milk fat was significantly decreased with the progress of the early lactation period (P=0.032). However, the percentages of total solids and SNF were significantly increased in E2 and E3 stages when compared with the E1 stage (P=0.001 and 0.018, respectively). The serum glucose and total antioxidant capacity were considerably reduced with the progress of the lactation period (P=0.047 and 0.039, respectively). In conclusion, Baladi goats showed a decreased serum progesterone level with the progress of the early lactation period and produce milk with a relatively stable protein and lactose contents. Furthermore, Baladi does able to maintain the stability of most blood biochemical parameters during such period.

Variations in some haemato-biochemical markers from a small flock of free ranging Nguni, Boer and Non-descript goats during late gestation and early lactation periods

This study aimed to assess the influence of genotype and physiological status on blood metabolites of Nguni (10), Boer (10) and Non-descript (10) goats during late gestation and early lactation periods. Blood samples were collected and analysed using standard methods. The result revealed that, Nguni goat had higher (P Lass Than 0.05) mean values of red cell counts (13.37 x1011/L), haemoglobin (9.07 g/dL) and creatine kinase (269.54 U/L) compared to Boer (9.96 x 1011/L, 7.94 g/ dL and 132.16 U/L) and Non-descript (12.98 x 1011 /L, 7.85 g/ dL and 143.50 U/L) goats, respectively. The Nguni goat also had higher mean values of glucose (3.38 mmol/L) and urea content (5.51 mmol/L) compared to Boer goats (2.96 mmol/L and 4.45 mmol/L) and Non-descript (2.50 mmol/L and 3.90 mmol/L). There was higher mean values of red cell counts (14.44 x 1011 /L), haemoglobin (8.57 g/dL), glucose (3.12 mmol/L), sodium (141.74 mmol/L) and calcium content (2.37 mmol/L) during late gestation compared to early lactation (9.77 x 1011/ L, 8.00 g /dL, 2.77 mmol/L, 137.37 mmol/L and 2.23 mmol/L) period. It was concluded that, genotypes and physiological status had influence on blood metabolites of goats.

Development of a Fatty Liver Model by Restricted Feeding of Lactating Sheep

Background: As a frequent subclinical disease, fatty liver disease (FLD) is associated with a severe negative energy balance (NEB) during the early lactation period, and usually cause of economic loss to dairy farmers. Liver biopsy is the gold standard for the assessment of FLD. However, as an invasive procedure, liver biopsy has several limitations and such procedures are not readily available to dairy farmers. To further evaluate FLD in dairy cows, a FLD model of lactating sheep was developed by simulation of the state of negative energy balance (NEB).Materials, Methods & Results: Fourteen pregnancy thin-tail ewes were divided into control group (CG, n = 4), non-lamb restrained feeding group (NRG, n = 4) and single birth restrained feeding group (SRG, n = 6). After lambing, NRG and SRG ewe were received a feed restrained diet for 16 days. Liver biopsies and blood was collected on days 1, 4, 7, 10, 13, and 16, and biochemical parameters were analyzed. With restricted feeding and lactation administration, ewes in SRG showed increased liver fat concentrations (LFC) from days 4 post-administration and severe LFC was detected at day 13. Compared with CG, SRG sheep showed significant lower concentration of serum glucose (Glu) from days 7-13 and higher non-esterified fatty acid (NEFA) from days 4-16, β-hydroxybutyric acid (BHBA) from days 4-16, triglyceride from days 4-16, low-density lipoprotein cholesterol from days 4-16, lactate dehydrogenase (LDH) from days 13-16, aspartate aminotransferase (AST) at days 16. While, ewes in NRG showed normal LFC levels, and high concentration of serum Glu and insulin from days 4-16 were detected than CG and SRG ewes. With restricted feeding, ewes in NRG and SRG showed significant low level of revised quantitative insulin sensitivity check index from days 4-16 and high level of liver total cholesterol (TC) at day 16. Liver pathological characteristics showed LFC of NEB sheep was first detected around the liver portal area.Discussion: In this study, a model of FLD in lactating thin-tail sheep was developed by restricted feeding. Serum glucose concentrations were sharply decreased in SRG sheep，that was due to the large energy requirements for lactation and low energy provided by a restricted diet. While non-lactating NRG sheep demonstrated lower fat mobilization, which was considered to contribute to the high concentrations of serum glucose, as compared to SRG sheep. Meanwhile, in a state of NEB, oxaloacetic acid, which is generated by glycolysis and glycogenic amino acids, tends to be used for gluconeogenesis, that a generous amount of NEFA is incompletely oxidized to generate ketone body in SRG sheep, which is a major component of BHBA. Liver TC concentrations were significantly higher in NRG sheep than those in the SRG sheep, while liver triglyceride was significantly lower. The high level of liver TC in NRG sheep was considered to induce removal of triglyceride from the liver in the form of VLDL. Compared with CG sheep, although higher levels of liver TC were detected in SRG sheep on postpartum day 16, these levels were considered too low to induce significant depletion of triglycerides from the liver. In this study, the increase in serum AST and LDH was considered to cause by oxidative stress in mitochondria, and LDH concentrations was considered more sensitively than AST for LFC caused by NEB. Liver pathological characteristics showed that FLD caused by NEB had a major impact on reduced LFC, although no significant liver fibrosis was detected. While different from FLD caused by high-fat diet, TG was first accumulates around the hepatic lobules and LFC of NEB sheep was first detected around the liver portal area. It was considered that high concentrations of NEFA are prioritized for oxygenation in the liver portal area, which results in triglyceride accumulation.

ADSA Foundation Scholar Award: A role for serotonin in lactation physiology—Where do we go from here?

Lactation is a physiological event that is exclusive to mammals. Lactation evolved as a strategy to improve the survival of the young by providing them with the complete nutrition that is required for survival upon birth as well as maternal-offspring bonding. Typically, milk production by the dam matches the demand of the young. The dairy cow is a unique exception in which the discoveries and genetic selection related to lactation physiology have been applied and resulted in a dramatic increase in milk yield of dairy cows. Studies on the role of mammary-derived serotonin and the coordination of various aspects of milk production and maternal metabolism have revealed novel mechanisms by which milk production and maternal metabolism can be improved. Furthermore, the investigation into molecular and cellular mechanisms regulating mammary gland function has revealed the importance of epigenetics on mammary gland function. Understanding mammary gland function at the cellular and physiological levels will be important for improving mammary gland control of maternal metabolism during early lactation. The early lactation period is a critical time for a dairy cow as that is when she is most susceptible to disease and metabolic disorders that can lead to negative effects on her productive capacity and overall health. Our research in the area of serotonin physiology has illustrated the importance of serotonin on the regulation of lactation and maternal homeostasis. Future research in the area of lactation physiology should be targeted at improving maternal health and longevity in the herd through manipulation of the signals the mammary gland sends to coordinate maternal metabolism and synthesize milk. Specifically, we believe that serotonin will play a central role in understanding the communication between the mammary gland and the maternal physiology during lactation.

On-farm mortality and related risk factors in Estonian dairy cows

Mortality (unassisted death and euthanasia) reflects the health and welfare state of the cows and is associated with undesirable financial consequences for the farmer. The objective of this retrospective observational study was to identify risk factors associated with on-farm mortality in dairy cows. Data for a study period between January 1, 2013 and December 31, 2015 were retrieved from the Estonian Agricultural Registers and Information Board and Estonian Livestock Performance Recording, Ltd. Cows from milk-recording herds with ≥20 cow-years were included. Analyses included data of 86,459 primiparous cows from 409 herds and 109,314 multiparous cows from 410 herds. Cows were followed from the day of calving until exit from the herd due to on-farm death or euthanasia (defined as mortality), slaughter, or selling. Associations between risk factors and mortality were assessed using Weibull proportional hazard models.The mortality rate (MR) was lower in primiparous cows (MR = 5.09 per 100 animal-years, 95% confidence interval [CI] 4.93; 5.26) compared to multiparous cows (MR = 8.28 per 100 animal-years, 95% CI 8.13; 8.44). The early lactation period was associated with greater mortality hazard.Animal-level factors significantly associated with higher mortality hazard in primiparous and multiparous cows were Holstein breed, older age at first calving, having an assisted calving or stillborn calf. In multiparous cows, male sex of the calf, birth of twins/triplets, older parity, longer previous inter-calving interval and milk somatic cell count over 200,000 cells/ml at the last test-milking of the previous lactation were associated with greater mortality hazard. Lower milk yield, somatic cell count over 200,000 cells/ml and fat/protein ratio over 1.5 at first test-milking were associated with greater mortality hazard during the lactation.Cow mortality risk was greater in larger herds, in herds with lower cow conception rate and poorer longevity of cows. Also, lower herd average milk fat/protein ratio and decreasing herd size (for multiparous cows) as well as Northeast region were herd level risk factors.This study outlines the importance of herd management and good health of the cows at dry-off and during early lactation and ensuring easy calving to reduce mortality of cows.