Systematic review of hormonal strategies to improve fertility in rams

Reviewing the current state of knowledge on reproductive performance and productive traits in rams has many advantages. First, the compilation of this information will serve as a literature resource for scientists conducting research around the world and will contribute to the understanding of the data collected and interpreted by researchers on the different hormonal strategies used to improve reproductive performance in rams. Second, it will allow scientists to identify current knowledge gaps and set future research priorities in ram reproduction. Rams play an important role in the global flock economy, but their reproductive analysis has been limited in the use of hormonal technologies to increase the productivity of sheep flocks. In this review, we cite the most important works on six hormones that, in one way or another, modify the hypothalamus-pituitary-gonadal axis, at different doses, in and out of the reproductive season, breeds, application methods, among other factors. The overall aim is to increase the reproductive efficiency of rams in different scenarios and, in some cases, of other species due to the lack of limited information on rams.

Reproductive seasonality of hair rams under tropical conditions: an alternative for non-seasonal lamb production?

Reproductive seasonality limits the periods of breeding on the year and, therefore, productive output. However, some breeds appear as probably non-seasonal. The aim of the study was to characterize the seasonal pattern of Santa Inês rams, including an ultrasound characterization of the reproductive tract, testosterone concentrations, and semen characteristics. Fifteen Santa Inês rams remained in a grazing system with concentrate supplementation, and measurements of the reproductive tract and ultrasound evaluation (biometrics and pixel intensity) of the testicles and accessory sex glands were monthly recorded. Computerized seminal evaluations were also performed monthly, and serum testosterone concentration was measured every 15 days. Body weight and condition remained stable throughout the year. In general, reproductive traits varied along the year and reached maximum values during autumn and minimum in spring. Despite that, as fresh semen remained with enough quality to breed all along the year, seasonality does not appear as a limiting factor to breed along the year. Therefore, Santa Inês rams can be used for all-year-round breeding or for crossbreeding when rams from other breeds decrease their fertilizing ability.

Ultrasound Diagnosis in Small Ruminants: Occurrence and Description of Genital Pathologies

This study reports the occurrence and appearance of various reproductive tract pathologies of small ruminants diagnosed using ultrasound. An eight-year retrospective study of collected ultrasound data was carried out in Rio de Janeiro State, Brazil from September 2012 to July 2020. A total of 3463 animals from 16 sheep flocks and 10 dairy goat flocks, raised under extensive and intensive management systems, respectively, were used in the study. All animals were submitted to an ultrasound examination of their reproductive tract. Data were analyzed using Fisher’s exact test (p < 0.05), to compare disorder frequencies within and between species. Ewes (4.14%) had fewer reproductive disorders than does (8.98%), while rams (43.63%) and bucks (56.25%) presented no significant differences. Hydrometra was the most frequent finding in does, represented by 50.98% of cases; while, in ewes, recent fetal loss (22.85%) and cystic endometrial hyperplasia (20.00%) were the most frequent. In bucks, the findings showed no clear differences; while, for rams, the most frequent finding was testicular microlithiasis (75.00%). Ultrasonography offers clinically useful information about the reproductive tract via the images it provides; knowledge of which makes it possible to improve the diagnosis, therapy, and prognosis of genital pathologies.