Effects of source of supplementary trace minerals in pre- and postpartum diets on reproductive biology and performance in dairy cows

Effects of Replacing Inorganic Sources of Copper, Manganese, and Zinc with Different Organic Forms on Mineral Status, Immune Biomarkers, and Lameness of Lactating Cows

(Objectives) The objectives of this study were to evaluate the effect of half-replacement of the supplementary sulfate sources of Cu, Mn, and Zn with methionine-hydroxy-analog-chelated (MHAC) mineral or amino-acid-complexed (AAC) mineral forms in diets on the mineral status, blood immune biomarkers, and lameness of lactating cows. (Methods) Sixty multiparous Holstein cows (158 ± 26 days in milk; body weight: 665 ± 52 kg; milk yield: 32 ± 7 kg/day) were randomly assigned into one of three dietary treatments (n = 20 per group): (1) MHAC: 50% replacement of sulfate minerals with MHAC forms. (2) AAC: 50% replacement of sulfate minerals with AAC forms. (3) S: 100% sulfate minerals (control). Their Cu, Mn, and Zn concentrations, blood immune biomarkers, and lameness were measured monthly. Repeated-measure mixed models were used to evaluate the effects on trace mineral status over time. As the responses with the MHAC and AAC forms were similar, the treatments were also analyzed as organic trace minerals (OTMs, combining the MHAC and AAC groups, n = 40) versus inorganic trace minerals (ITMs, the S group, n = 20). (Results) Cows supplemented with OTMs had higher concentrations of Cu and Mn in their serum (p ≤ 0.05), a higher hoof hardness (p ≤ 0.05), and a lower incidence of lameness compared to those with ITMs on d 90. There were no statistical differences (p > 0.10) in the concentrations of IgA, IgG, or ceruloplasmin, but there were significant differences (p = 0.03) in the concentrations of IgM in the serum as fixed effects of the diet treatments during the whole trial. On d 30 and 90, the serum IgA concentrations of the cows supplemented with OTMs tended to be higher (0.05 < p ≤ 0.10) than those in the cows supplemented with ITMs. (Conclusions) The half-replacement strategy showed that the MHAC and AAC sources of Cu, Mn, and Zn additives had similar effects on the production performance, blood immune biomarkers, and lameness of the lactating cows. The long-term replacement strategy with OTMs led to the enhancement of the trace mineral concentrations in their body fluids, blood immune biomarkers, and hoof health.

Endometrial responsiveness to interferon-tau and its association with subsequent reproductive performance in dairy heifers

Our objectives were to evaluate the endometrial responsiveness of dairy heifers to an intrauterine infusion of recombinant bovine interferon-tau (rbIFN-τ) and to associate endometrial responses to rbIFN-τ with subsequent reproductive performance. In experiments 1 and 2, cyclic heifers were enrolled in a program for synchronization of the estrous cycle, and blood sampling and ultrasonography examinations were performed on d 0, 4, 7, 11, and 14 of the estrous cycle. In experiment 1, heifers were randomly assigned to receive an intrauterine infusion containing 2 µg of rbIFN-τ (rbIFN-τ = 19) or saline control (CTRL = 19) into the uterine horn ipsilateral to the corpus luteum (CL) on d 14 of the estrous cycle. Then, 6 hours after the infusion, the infused uterine horn was flushed for sampling of the uterine luminal fluid (ULF) for composition analysis, and the endometrium was biopsied for transcriptomics. In experiment 2, 100 heifers received an intrauterine infusion of rbIFN-τ, and the same procedures for uterine sample collection were performed as described in experiment 1. After the intrauterine test, heifers were enrolled in a breeding program and classified as highly fertile (HF; pregnant at first AI) or subfertile (SF; not pregnant at first AI). Statistical analyses were performed using regression models, which included the effects of treatment (experiment 1: CTRL vs. rbIFN-τ) or fertility group (experiment 2: HF vs. SF) and block of samples. Intrauterine infusion of rbIFN-τ increased the expression of classical interferon-stimulated genes in the endometrium (e.g., ISG15, MX1, OAS2, IRF9, and USP18), and an antiviral response was predicted to be the main downstream effect of the transcriptome changes. In addition, rbIFN-τ increased the abundance of cholesterol, glycerol, and the overall concentration of oxylipins in the ULF. Analysis of endometrial transcriptome between HF and SF heifers revealed important differences in the expression of genes associated with cell signaling, metabolism, attachment, and migration, with a large representation of genes encoding extracellular matrix proteins. In general, differentially expressed genes were expected to be downregulated by IFN-τ but seemed to fail to be downregulated in SF heifers, resulting in higher expression in SF compared with HF heifers. Subfertile heifers had lower concentrations of glycerol and an altered profile of oxylipins in the ULF, with a lower abundance of oxylipins derived from arachidonic acid and dihomo-γ-linolenic acid, and a greater abundance of oxylipins derived from linoleic acid. Measurements of ovarian function did not differ between groups and, therefore, did not influence the observed results in uterine biology. Overall, the endometrial responsiveness to IFN-τ is variable among individuals and associated with subsequent fertility of heifers, indicating that communication between conceptus and endometrium is critical for the uterine receptivity and survival of pregnancy.

Associations of postpartum health with progesterone after insemination and endocrine signaling during early pregnancy in dairy cows

Our objective was to investigate associations of postpartum health with serum progesterone (P4) concentrations after first artificial insemination (AI), expression of interferon-stimulated genes (ISG) in blood leukocytes, and serum pregnancy-associated glycoprotein (PAG) during early pregnancy in dairy cows. In this observational study, Holstein cows (n = 475) from 2 commercial herds were enrolled 3 wk before expected parturition. Body condition score (BCS) and lameness were assessed at enrollment, and total Ca, haptoglobin, and nonesterified fatty acids (NEFA) were measured in serum at 2 and 6 ± 2 d in milk (DIM). Blood β-hydroxybutyrate and metritis were evaluated at 4, 8, 11, and 15 ± 2 DIM, and purulent vaginal discharge (PVD) and endometritis based on endometrial cytology were diagnosed at 35 DIM. Onset of cyclicity was assessed by biweekly P4 measurements. The BCS was assessed at enrollment and at 63 DIM, and lameness at enrollment and at 21 and 49 DIM. First AI was based on estrus detection until ∼75 DIM, or synchronization for timed AI thereafter. Serum P4 was measured at d 8 and 12 after first AI; expression of ISG (ISG15 and RTP4) in blood leukocytes was assessed at d 19; and PAG in serum of pregnant cows was measured at d 29, 33, and 40. Multivariable linear regression models were built including health variables (with metabolites categorized via receiver operating characteristic curve analysis) and covariates (season, milk yield, AI method, DIM), accounting for pregnancy status (for ISG and PAG models), repeated measures (for P4 and PAG models), and herd as random. Results are reported comparing cows affected versus unaffected by each predictor. Serum P4 concentrations were lesser at d 8 after AI in cows that had total Ca ≤2.09 mM (3.6 vs. 4.0 ± 0.2 ng/mL) at 2 DIM or a clinical disease (3.7 vs. 4.0 ± 0.2 mg/mL), and P4 tended to be lesser at d 8 in cows that had PVD (3.6 vs. 4.0 ± 0.2 ng/mL) or any uterine disease (3.7 vs. 4.1 ± 0.2 ng/mL). Among cows pregnant at d 29, relative ISG15 expression (fold change) at d 19 was greater in cows that had lameness (5.10 [4.18-6.18] vs. 3.14 [3.10-3.19]) but tended to be lesser in cows that had endometritis (3.20 [2.89-3.54] vs. 4.29 [4.20-4.35]), and relative expression of RTP4 tended to be lesser in cows that had displaced abomasum (1.02 [0.62-1.67] vs. 1.75 [1.73-1.78]). Serum PAG was lesser at d 29 (3.8 vs. 4.2 ± 0.2 sample-to-positive ratio [S:P]) in cows that had NEFA ≥0.73 mM at 6 DIM, and lesser at d 33 (3.9 vs. 4.5 ± 0.2 S:P) and 40 (3.1 vs. 3.7 ± 0.2 S:P) in cows that had prepartum BCS ≥3.75. These findings suggest long-term effects of metabolic or reproductive tract disorders on luteal function after first AI, pregnancy recognition signaling, and placental function during early pregnancy. These associations may partially explain some of the pathways linking postpartum health and fertility in dairy cows.