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The main objective of this study was to evaluate the effect of peripartal administration of a commercially available nonspecific immune stimulant (mycobacterium cell wall fraction; MCWF [Amplimune, NovaVive Inc. Napanee, ON, Canada]) on the incidence of disease during early lactation and subsequent fertility of dairy cows. A second objective was to characterize the dynamics of circulating white blood cells (WBC) and metabolic markers following treatment administration. Cows in an United States Department of Agriculture (USDA) organic-certified dairy herd were blocked by parity and, based on sequential calving dates, randomly assigned to receive two injections (5 mL s.c.) of either a placebo (saline solution) as a control (CON ; n = 71) or MCWF (n = 65) at enrollment (7 d before expected calving) and within 24 h after calving. Blood samples were collected from a subsample of the study population (MCWF = 16; CON = 18) for WBC count at enrollment, at day 2 post enrollment, and at days 1, 3, 7, and 14 after calving. Serum fatty acids, beta-hydroxybutyrate, and Ca concentrations were determined at days 1 and 7 postpartum (MCWF = 21; CON = 21). Main outcome variables included incidence risk of peripartal and early lactation health disorders and pregnancy at first artificial insemination (AI), at 100, and at 150 days in milk (DIM). In addition, the average daily milk yield up to 90 DIM and death and live culling before 305 DIM were compared. Treatment effects were assessed using multivariable logistic regression, time-to-event analyses, and repeated measures analysis of variance (ANOVA). A treatment effect on the incidence risk of some of the health disorders in the study was established. Incidence risk of metritis and clinical mastitis <28 DIM was smaller in MCWF than in CON cows (36.9% vs. 50.7% and 6.3% vs. 19.7%, respectively). On the contrary, the incidence risk of respiratory disease <28 DIM was smaller in CON (0%) than in MCWF (7.7%). Reproductive performance of multiparous cows was affected by MCWF administration: pregnancy at first AI and pregnancy at 100 and 150 DIM were greater in MCWF than in CON (35.6% vs. 19.2%; 51.1% vs. 25.0%; and 64.4% vs. 40.4%, respectively). Overall, median intervals from calving to pregnancy were 90 vs. 121 d in MCWF and CON cows, respectively. No treatment effects on the dynamics of circulating WBC or in postpartum metabolic status were established. No differences for milk yield or for the proportion of cows that survived up to 305 DIM were determined, although cows in MCWF left the herd earlier than cows in CON. In conclusion, incidence risks of metritis and mastitis in early lactation were smaller in cows receiving MCWF, whereas the incidence risk of respiratory disease was smaller in CON. Fertility significantly improved in MCWF compared with CON cows. As this study was performed in an organic-certified dairy, specific health and reproductive management practices may affect the external validity of the current findings. [ABSTRACT FROM AUTHOR]

Investigating the influences of single nucleotide polymorphisms (SNP) associated with conceptus death (CD) on day 16 of pregnancy could distinguish cows who have inferior value for fertility traits. We hypothesized that CD is associated with SNP genotypes that disrupt maternal recognition and lead to early pregnancy loss. RNA sequences from Holstein cow pregnancies (n = 15) with normal conceptuses (Norm) or CD were subjected to SNP discovery via Qiagen CLC Genomics Workbench. Selected SNP were based on previous fertility studies, differentially expressed genes within pregnancy development analyses and proximity to SNP associated with fertility traits in the Cattle QTL Database. A second cohort of Holstein cows (n = 500) was used to conduct a validation and genotype to phenotype analysis of candidate SNP (cSNP) via DNA from blood samples and farm records. PLINK software was used to remove cows (n = 34) missing more than ≥20% cSNP and remove cSNP with monomorphic alleles, minor allele frequency (MAF) < 10% and not in Hardy-Weinberg Equilibrium (>1e-15). The GLM-one way ANOVA was used for all statistical models in SAS. Statistically significant models (P <0.05) were further analyzed for LSMEANS, Bonferroni adjustment of P-values, additive allele effect and predicted effect of amino acid (aa) change on protein function via SIFT analyses tool in the Ensembl variant table (scoring 0-1.0; ≥ 0.05 being significant). Previously, we identified 69 cSNP on the RNA sequences of Norm or CD pregnancies from the initial group of Holstein cows and in proximity to ≥1 SNP associated with fertility traits from the Cattle QTL database. Quality control measures in PLINK reduced the number of Holstein cows in the second cohort to 466 and identified 4 cSNP associated with non-binary reproductive traits. Herein, we report an additional 4 cSNP discovered and validated with binary reproductive traits. The cSNP within genes were associated with the following roles: BOLADMB (antigen loading in the immune system), DECR1 (lipid metabolism), FASN (reconstitution of body reserves during pregnancy) and SREBF1 (synthesis of fatty acids). Cows with T allele, in BOLA-DMB and SREBF1, were less likely (P < 0.05) to become pregnant ≤150 days in milk (DIM). For DECR1 and FASN, cows were less likely (P < 0.05) to become pregnant at 1st artificial insemination with C or A allele, respectively. Only the cSNP in SREBF1 had both an additive allele effect and a predicted effect of aa change on protein function. When cows had C allele, in the SREBF1 cSNP, there was 6% greater (P < 0.01) probability of becoming pregnant <150 DIM. While SIFT revealed the cSNP in SREBF1 have a predicted significant effect with a score of 0.03 for the aa change of proline/leucine. The reported cSNP, specifically those influenced by CD, add valuable information for the development of improved genetic tools for the dairy industry. USDA-NIFA#2019-07133. [ABSTRACT FROM AUTHOR]