Review: Postpartum reproductive disease and fertility in dairy cows

Effects of systemic or uterine endotoxin challenge in Holstein cows at 5 or 40 days postpartum on clinical responses, uterine and systemic inflammation, and milk yield

Our objective was to investigate the effects of intravenous (IV) or intrauterine (IU) lipopolysaccharide (LPS) challenge at 5 or 40 d postpartum (DPP) on clinical signs, systemic and uterine inflammation, dry matter intake (DMI), and milk yield (MY). Holstein cows at 5 DPP (n = 23) or at 40 DPP (n = 24) were blocked by parity and randomly assigned to one of 3 treatments: 1) IV-LPS [0.0625 μg/kg BW (5 DPP) or 0.1 μg/kg BW (40 DPP) over 1h], 2) IU-LPS [100 μg (5 DPP) or 300 μg (40 DPP) in 20 mL saline], or 3) 20 mL saline IU (IU-SAL; same for 5 and 40 DPP). The proportion of polymorphonuclear (PMN) cells was measured by endometrial cytology at d -1, 1, 4, and 7 relative to treatment. Blood haptoglobin (Hp), serum-amyloid A (SAA), and LPS-binding protein (LBP), DMI, and MY were measured from d -1 through 7. Data were analyzed separately for each DPP group in multivariable linear regression models accounting for repeated measures. For both DPP groups, there were increases in rectal temperature, heart and respiratory rates, and a decrease in rumination rate following IV-LPS, but not following IU-LPS. At 5 DPP, endometrial PMN proportion was similar in IU-LPS and IU-SAL. Serum Hp was unaffected by LPS challenge, SAA was greater in IV-LPS from 12 to 24 h after challenge, and LBP was greater in IV-LPS from 8 to 24 h. At 40 DPP, PMN was greater in IU-LPS (37 ± 4%) than in IU-SAL (15 ± 4%) 1 d after LPS challenge. Serum Hp was greater from 24 to 72 h after challenge in IV-LPS than in the other groups, SAA was greater in IV-LPS from 6 to 48 h, and LBP was greater in IV-LPS from 8 to 24 h. At both 5 and 40 DPP, treatment did not affect DMI, but MY was lesser in IV-LPS cows at 12 and 24 h than in IU-SAL or IU-LPS. The IV-LPS challenge resulted in more pronounced changes in clinical signs and acute phase protein (APP) concentrations than IU-LPS or IU-SAL at 40 DPP, but more subtle or inconsistent changes at 5 DPP. These may be due to the different doses of LPS used at 5 and 40 DPP or possibly due to the high variation in baseline clinical signs and APP observed in all groups at 5 DPP. The IU-LPS increased uterine PMN 1 d after challenge at 40 DPP, but not at 5 DPP. At each time, IU-LPS did not produce changes in clinical signs or markers of systemic inflammation.

Supplementation of rumen-protected lysine during the close-up period improves vaginal discharge clearance in Holstein dairy cows

We aimed to evaluate the effects of rumen-protected lysine (RPL) supplementation during the close-up period on uterine involution and the resumption of ovarian function in dairy cows. Fifty-two multiparous Holstein cows were categorized based on parity and expected calving date and randomly assigned to the RPL or control (CON) groups. The RPL group received 80 g of RPL daily from day 21 before the expected calving date until parturition. Blood samples were obtained twice weekly from pre-supplementation to 6 weeks postpartum. The onset of luteal activity postpartum was determined via ultrasonography twice weekly for up to 6 weeks postpartum. Uterine involution was tracked at 3 and 5 weeks postpartum through the vaginal discharge score, percentage of polymorphonuclear cells (PMN) in endometrial cytology samples, presence of intrauterine fluid, and gravid horn diameter via ultrasonography. Before supplementation, the RPL group showed amino acid imbalance, which was improved by RPL supplementation. There were no significant differences in the onset of luteal activity, percentage of PMN, intrauterine fluid, or the diameter of the uterine horn between the two groups. The vaginal discharge score in the RPL group decreased from 3 to 5 weeks postpartum, whereas that in the CON groups did not decrease. The number of cows with clinical endometritis was lower in the RPL group. Overall, RPL supplementation during the close-up period enhanced vaginal discharge clearance, potentially averting clinical endometritis, but did not affect the first ovulation in dairy cows.

Temporal changes in ewe vaginal microbiota throughout gestation

Introduction

Numerous factors are known to influence reproductive efficiency in ewes, but few studies have investigated the potential role of vaginal microbiota in sheep reproductive success. The objective of this study was to thoroughly characterize the ewe vaginal microbiota throughout the course of pregnancy.

Methods

Vaginal samples were collected from 31 pregnant Hampshire and Hampshire X Suffolk crossbred ewes on a weekly basis from pre-breeding to pregnancy testing and then biweekly until just after lambing. To characterize the vaginal microbial communities, DNA was extracted and 16S rRNA gene Illumina MiSeq amplicon sequencing was performed.

Results and Discussion

Alpha diversity metrics indicated an increase in species richness, evenness, and overall diversity throughout gestation. Distinct shifts in the bacterial communities were observed during gestation and were segregated into three periods: early gestation, a transitional period and mid/late gestation. During early gestation, Actinobacillus, Histophilus, and unclassified Leptotrichiaceae were found in greater relative abundance. During the transitional period, a population shift occurred characterized by increasing relative abundance of Streptococcus and Staphylococcus. During mid/late gestation, Staphylococcus, Streptococcus, and Ureaplasma had the greatest relative abundance. These shifts in the microbial population throughout the ewe's gestation are likely related to hormonal changes triggered by the growing conceptus, specifically increasing blood concentration of progesterone. The transitional period shift in vaginal microbial communities potentially aligns with the placental take-over of progesterone production from the corpus luteum at approximately day 50 after conception (gestational week 7). Understanding the observed variability of the vaginal microbiota throughout pregnancy will allow for future comparison of ewes that did not become pregnant or had abnormal pregnancies, which could lead to the discovery of potential bacterial biomarkers for pregnancy outcome; this understanding could also lead to development of probiotics to improve sheep reproductive success.