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Milk production has doubled from 1970 to 2009 but has been associated with a decline in fertility. Around 25% of failed pregnancies in dairy cattle are due to embryonic loss. Mineral bioavailability may affect embryonic retention, so we hypothesized that Zn, Cu, and Mn sources will influence systemic immunological status, which affects early embryonic retention. Holstein cows (n = 58) were randomly assigned to one of two daily oral drench trace mineral (Zn, Cu, and Mn) treatments 30 d before breeding (d -30): 1) Inorganic (ITM) or 2) Metal Methionine Hydroxy Analog Chelate (MMHAC). Before treatments began, cows were assigned to a semen type, beef vs. Holstein, equally, across treatments. All cows underwent a double Ovsynch protocol and were artificially inseminated on d 0. Humoral immunological status was assessed in serum samples taken on d 0 and d 7. Immune activity was quantified via a D2Dx systemic immunity score, which assesses samples for the presence of IgG, IgM, cytokines, and complement proteins. Ultrasonography was utilized for pregnancy confirmation on d 35, classifying cows as pregnant (P) or open. Progesterone analysis from d 21 plasma was used to categorize open cows as either non-pregnant (NP) or early embryonic loss (EEL). Statistical analyses in R Studio were completed, in two models based on pregnancy (P vs EEL and NP vs EEL), to determine the effects of mineral treatment, pregnancy status, semen type, and all interactions on humoral immune status. In the P vs EEL model, there were no effects (P > 0.30) of semen type, mineral treatment, pregnancy status, or any interactions on systemic immunity score on the day of breeding (d 0) or d 7. On d 0, cows provided MMHAC had a systemic immunity score of 0.073 ± 0.008 but were not different (P > 0.34) from ITM cows (0.063 ± 0.006). This trend continued on d 7 with systemic immunity scores of MMHAC cows not differing (P > 0.32) from ITM cows (0.055 ± 0.004 and 0.061 ± 0.003; respectively). There was a tendency (P = 0.10) for the three-way interaction of semen type x pregnancy x treatment to influence the immunity score change from d 0 to d 7. Pregnant cows on ITM treatment bred with beef semen had a positive change in immunity score (0.020 ± 0.0085). Whereas ITM cows bred with Holstein semen that underwent EEL had a negative change (-0.015 ± 0.0085); all other means were intermediate. In the NP vs EEL model, there were no effects (P > 0.14) of semen type, treatment, pregnancy status, or any interactions on systemic immunity score on d 0, d 7, or the change between d 0 and d 7. In summary, trace mineral bioavailability tended to affect systemic immunological status in P vs EEL cows but not in NP vs EEL cows, which may allow for the elucidation of immunological status differences during pregnancy establishment. [ABSTRACT FROM AUTHOR]

Blood tests to determine pregnancy status as early as 28 days post-breeding based on circulating concentrations of pregnancy-associated glycoproteins (PAGs) are currently available for use in the beef industry. The objective of this study is to determine the accuracy associated with determining early embryonic loss based on visual observation of color change and optical density (OD) using the IDEXX bovine pregnancy test and the IDEXX rapid visual test. Beef cattle from 6 different herds were synchronized using a recommended CIDR based protocol. Pregnancy status was first determined by transrectal ultrasonography between day 32 to 42 post-breeding and blood samples were collected from pregnant animals at this time (n = 492). A final pregnancy determination was performed after the end of the breeding season to determine embryonic loss. Each serum sample was examined in duplicate using the IDEXX Bovine Pregnancy Test and the IDEXX Rapid Visual Test. The results from both the bovine pregnancy test and the rapid visual test were analyzed using a microtiter plate reader. Additionally, the rapid visual test was individually scored and evaluated by two technicians unaware of pregnancy status or embryonic loss. The scoring system consisted of yes/no and a numerical value (0-3) based on color compared to negative and positive controls. Data was analyzed using the GLIMMIX procedure of SAS with herd as a random variable. Overall there were 28 (5.7%) animals that lost an embryo. The bovine pregnancy test indicated decreased circulating concentrations of PAGs in animals that lost an embryo (P = 0.01; 2.45 ± 0.11 vs 2.74 ± 0.04 OD). With the rapid visual test both technicians visually scored the animals that lost an embryo lower compared to animals that did not lose an embryo (P < 0.01; 2.77 ± 0.6 vs 2.93 ± 0.01 and 2.78 ± 0.06 vs 2.96 ± 0.03 for technician 1 and 2, respectively). However, of the animals that lost an embryo only two were identified as not pregnant by the rapid visual test, and of the animals that maintained their embryo only one was falsely identified as not pregnant (0.2%). In summary, both bovine pregnancy tests were sensitive at detecting differences in circulating PAGs among animals that experienced embryonic loss, but the majority of these animals would have been classified as pregnant at time of sample collection. [ABSTRACT FROM AUTHOR]