Jacobo Álvarez

Las patologías uterinas postparto afectan significativamente la eficiencia reproductiva del ganado vacuno lechero. En las últimas décadas ha habido un creciente interés científico en la endometritis subclínica (ES) debido a su elevada prevalencia y efectos en la fertilidad. Pese al elevado número de trabajos científicos sobre esta patología, no existe consenso sobre el tratamiento específico. El tratamiento más común ha consistido en la aplicación de antibióticos y antiinflamatorios, pero en base a los nuevos hallazgos respecto a su fisiopatología y a las resistencias generadas actualmente no se considera el tratamiento más adecuado. El tratamiento con prostaglandinas, individualmente o combinadas con antibiótico, también se ha empleado con frecuencia, pero debido a la heterogeneidad de resultados tampoco se han logrado resultados concluyentes sobre su eficacia. Estas inconsistencias han generado diferentes opiniones entre los expertos, así como la necesidad de explorar tratamientos alternativos. La prevención es clave, enfatizando un adecuado manejo y nutrición para evitar el balance energético negativo excesivo, manejo higiénico del parto y control de enfermedades metabólicas. Según investigaciones recientes, el uso de antioxidantes, probióticos y ácidos grasos omega‑3 contribuyen modestamente a la salud uterina y a una mejor eficiencia reproductiva, por lo tanto, se consideran prometedoras. Sin embargo, persiste la necesidad de investigaciones para optimizar diagnósticos y tratamientos, abordando enfoques innovadores y personalizados.

Prompt identification of clinical signs and early treatment of hoof problems are essential to effectively manage and reduce lameness in dairy farms. This study aimed to evaluate the influence of days in milk (DIM), parity, and milk yield (MY) on the mean temperature (MT) of the hind hooves in healthy cows, with the perspective of implementing infrared thermography (IRT) as an automated tool for early lameness detection. Thermal images were collected from 156 milking cows, capturing both cranial and caudal surfaces of each hind foot. Significant differences were found between primiparous and multiparous cows across all analyzed surfaces. Moreover, cows with higher milk production exhibited significantly higher MT in the caudal left hoof and on both cranial surfaces. The variable DIM (group 1 = cows with ≤202 DIM; group 2 = cows with >202 DIM) did not significantly affect MT on caudal surfaces; however, on the cranial view, MT of the right hoof was higher in group 2, while group 1 tended to show higher MT in the left hoof (p = 0.051). In conclusion, hoof MT increases in multiparous and high-producing cows. Additionally, during the first 200 days of lactation, cranial hoof surface temperatures tend to rise. Future studies should include continuous monitoring using automated systems to record variations throughout the day.

Pheromones are defined as substances released by an individual that have a specific influence on physiology, behaviour or development with another individual of the same species. Currently, the term pheromone is used in various disciplines, from psychology to electrophysiology, or to describe various chemosensory stimuli. The present literature review describes the main pheromone receptors and sources in rabbits, including the vomeronasal organ and the olfactory bulb; the main pheromone-producing glands are also described, such as the chin, anal, Harderian, mammary and the brown inguinal, as well as the urine as the major source for pheromonal communication. This review also provides a comprehensive examination of the role of pheromones in rabbit behaviour, integrating perspectives from physiology, behaviour and practical applications in rabbit farming. It delves into the mechanisms of pheromone action by discussing the main receptors and production sites, categorising pheromones in an orderly manner according to their functional roles in rabbits. Additionally, the review synthesises current research on pheromone influence, while highlighting both ecological implications and welfare improvements. By addressing these topics with scientific depth and practical relevance, this work offers an insightful understanding of rabbit pheromones and their diverse roles.

This study aimed to evaluate the accuracy of the accelerometer-equipped collar RUMI to detect estrus in dairy cows, establish a recommendation for the optimal timing for artificial insemination (AI) when using this device, and characterize the blood flow of the dominant follicle (F) and the corpus luteum (CL) as ovulation approaches. Forty-seven cycling cows were monitored following synchronization with a modified G6G protocol, allowing for spontaneous ovulation. Ultrasound examinations were conducted every 12 h, starting 48 h after the second PGF2α dose, to monitor uterine and ovarian changes. Blood samples were also collected to determine serum progesterone (P4) levels. Each cow was fitted with a RUMI collar, which continuously monitored behavioral changes to identify the onset, offset, and peak of activity of estrus. One-way ANOVA assessed the relationship between physiological parameters and time before ovulation. Results showed that the RUMI collar demonstrated high specificity (100%), sensitivity (90.90%), and accuracy (93.62%) for estrus detection. The optimal AI window was identified as between 11.4 and 15.5 h after heat onset. Increased blood flow to the F and reduced luteal activity were observed in the 48 h prior to ovulation. Further research is needed to assess the influence of this AI window on conception rates, and if it should be modified considering external factors.

This study examined the prevalence and risk factors of repeat breeder syndrome (RB) in 2370 dairy cows in northern Spain. Data collected included the prevalence of postpartum pathologies, metabolic markers, and productive and reproductive parameters. The overall RB prevalence was 21.1%. In primiparous cows, the postpartum body condition loss (Odds Ratio (OR): 2.9–8.1, depending on severity), ketosis (OR: 3.5), lameness (OR: 3.4), clinical mastitis (OR: 4.2), dystocia (OR: 5.2), and endometritis (OR: 12.2) significantly increased the RB risk. Summer (OR: 0.4) or autumn (OR: 0.6) calvings reduced this likelihood compared to winter or spring calvings. In multiparous cows, risk factors included body condition loss (OR: 2.0), ketosis (OR: 4.3), lameness (OR: 2.5), clinical mastitis (OR: 4.2), dystocia (OR: 1.9), endometritis (OR: 6.2), metritis (OR: 1.38), and subclinical mastitis (OR: 1.9). A longer interval between calving and first postpartum insemination reduced the RB risk (OR: 0.99). Overall, metabolic and reproductive disorders were significant risk factors for RB across both cow groups, while seasonal calving and delayed insemination mitigated risk in primiparous and multiparous cows, respectively.

Repeat breeder (RB) syndrome plays a detrimental role on fertility and economic performance of dairy farms. Regarding its multifactorial origin, it has been stated that an immunological response in the female genital tract may impair sperm viability. Therefore, the aim of this study was to evaluate the concentration of immunoglobulins in cervical mucus of RB cows and its influence on sperm motility. Fifteen fertile cows and 32 RB cows were included in the study. Cervical mucus samples were collected at the time of artificial insemination (AI). The concentration of IgG and IgA was determined by radial immunodiffusion. Sperm motility in cervical mucus was evaluated by CASA system. Our results showed no significant differences between cows with or without RB syndrome regarding the concentration of immunoglobulins in cervical mucus and sperm motility. The only factor affecting sperm motility was time. Consequently, it may be probable that a local immune response against spermatozoa is not one common cause of RB syndrome.

Anogenital distance (AGD) is a marker of the degree of prenatal exposure to androgens in multiple species, and it has been suggested that there is an inverse association between AGD and fertility. Therefore, the aim of this study was to determine the usefulness of AGD and anti-Müllerian hormone (AMH) concentrations, an indirect marker of the follicular population, as predictors of future reproductive potential in Holstein cattle. The AGD was measured in 566 females from 9 dairy farms in Galicia (Spain). A group of 172 females underwent a second measurement 9 months after. Additionally, data on the age at first insemination (1stAI age), number of AI (AI-PREG), age at first pregnancy (1stPREG age), age at first calving (1stCAL age), and calving–pregnancy (CAL-PREG) and calving–calving (CAL-CAL) intervals were collected. Blood samples were collected from 80 heifers to determine AMH concentrations. Our results showed that AGD varied minimally with age, and that cows with short AGD had earlier 1stAI age, 1stPREG age, and 1stCAL age (p < 0.05) than cows with long AGD. No significant differences were observed for the CAL-PREG and CAL-CAL intervals. Additionally, no significant association was found between AMH concentration and AGD or reproductive parameters. Consequently, the results suggest the possibility of using AGD as a marker of future reproductive performance in Holstein heifers. However, there was insufficient evidence to associate AMH concentrations and reproductive performance, underlining the need for further studies with larger sample sizes.