National University of La Pampa

This study examined the association between energy metabolism-related variables and conception rate at first service (CRFS) in Holstein cows. It focused on identifying confounding relationships among key factors. Data came from a large dairy farm in Coahuila, Mexico. The dataset included 1056 lactations recorded in 2024. Of these, 419 were primiparous and 637 were multiparous cows. Only cows that completed a synchronization protocol and received timed artificial insemination (TAI) were included. A logistic regression model was used to predict CRFS. In the model, body condition score (BCS) at calving and postpartum diseases were not significant when subclinical ketosis (SCK) and BCS loss were included. This suggested confounding effects. Key associations were found: Cows with BCS ≥ 3.75 at calving were 5.55 times more likely to lose ≥ 0.75 BCS units by first breeding than cows with BCS ≤ 3.5. Cows with BCS ≤ 3.5 at calving were 0.45 times as likely to develop SCK compared to cows with BCS ≥ 3.75. Cows with postpartum diseases were 4.42 times more likely to develop SCK than healthy cows. Multicollinearity was observed between postpartum diseases and SCK and between BCS at calving and postpartum BCS loss. The best-fitting model for CRFS included: breeding season, milk yield at week 8 postpartum, parity, SCK, and postpartum BCS loss. SCK and BCS losses, as well as postpartum diseases, were key factors associated with CRFS and were also confounded by BCS at calving.

Gallic acid (GA) is an abundant natural phenolic compound found in foods such as tea, fruits, and beverages. Quantifying GA remains a key research area in analytical chemistry. Traditional methods, such as liquid chromatography, are time-consuming, highlighting the need for faster and more efficient techniques to quantify GA concentration. This study proposes an approach based on the MCR-ALS algorithm to model second-order voltammetric data obtained by varying the scan rate. Data preprocessing and subsequent mathematical modeling enabled the quantification of GA with a detection limit of 5.9 mg L^-1, below the stipulated concentrations for the analyte in various food matrices. Quantification was achieved even in the presence of unmodeled interferences, leveraging the second-order capabilities of multivariate calibration methods. This approach allows for accurate results to be obtained in a direct, fast, and reliable manner, representing a breakthrough in food industry quality control and opening new perspectives for food quality assessment.

The objective of the present study was to evaluate the effects of a synthetic eCG-like glycoprotein treatment, body condition score changes, and postpartum nutritional supplementation on follicular and luteal characteristics and pregnancy rates in suckled beef cows synchronized with a 7-d Co-Synch protocol. In Experiment I, 1218 suckled cows received a progesterone intravaginal device (1.0 g; IVD) and 100 μg GnRH on Day -10. On Day -3, IVDs were removed, and cows received 0.5 mg sodium cloprostenol and were randomly assigned to receive either 400 IU eCG-like glycoprotein (eCG-like; n = 602) or no eCG-like glycoprotein (Control; n = 616). On Day 0, 100 μg GnRH was given concurrently with TAI. Body condition score (BCS) was recorded on Day -10 and 35, and its change was calculated. Corpus luteum (CL) presence was evaluated on Day -10, and pregnancy (P/TAI) on Day 35. In cows without CL, eCG-like increased estrus expression rate (EER; 58.2 vs. 45.3 %; P = 0.01). In cows that lost BCS, eCG-like increased P/TAI (47.2 vs. 32.1 %; P = 0.01). In Experiment II, 72 cows, 21 d postpartum, were assigned to supplemented (SUP; 4 kg of corn daily) or non-supplemented (NSUP) diets for 80 days. Cows were subjected to the same synchronization protocol and eCG-like glycoprotein treatment described in Exp. I. Nutritional SUP increased (P ≤ 0.05) body weight and BCS. Dominant follicle (DF) growth tended to be greater in eCG-like group than Control (1.2 vs. 0.7 ± 0.3 mm/d; P = 0.08), while the SUP group exhibited greater ovulation rate and CL area compared with NSUP (P ≤ 0.03). The eCG-like treatment increased EER in cows without CL and P/TAI in those losing BCS. Although eCG-like tended to improve DF growth, no interaction was observed between nutritional and eCG-like treatment on follicular and luteal characteristics.