Plasma, milk and faecal progesterone concentrations during the oestrous cycle of lactating dairy cows with different milk yields

Opportunities and challenges associated with fecal progesterone metabolite analysis

Conventionally, plasma or milk progesterone evaluations are used to determine the reproductive status of female animals. Collection of such samples is often associated with difficulties of animal handling and restraint. Measurable quantities of progesterone metabolites are found in feces of animals. Their concentrations are known to be well correlated to plasma progesterone levels and are, therefore, used as non-invasive samples for assessing reproductive function in a wide range of animal species. Although the analysis of fecal progesterone metabolites has been widely accepted in many laboratories, several factors are known to affect the results from this valuable analytical technique. Some of these factors include storage/transportation media for fecal samples, type of solvent that is used for extraction of progesterone metabolites from feces, and the type and sensitivity of an assaying technique employed. Although fecal progesterone metabolites analysis is associated with some difficulties, it can effectively be used to monitor reproductive function in a wide range of animal species. This review aims to highlight the usefulness of fecal progesterone metabolite analysis as a non-invasive technique in monitoring reproductive function in animals. The article mainly focuses on the many opportunities and challenges associated with this analytical technique.

Circulating progesterone concentrations in nonlactating Holstein cows during reuse of intravaginal progesterone implants sanitized by autoclave or chemical disinfection

The aim of this study was to compare plasma progesterone (P4) concentrations in nonlactating, multiparous Holstein cows (n = 24) treated with 2 types of intravaginal implants containing either 1.0 or 1.9 g of P4 either at the first use or during reuse of the implants after sanitizing the implant by autoclave or chemical disinfection. In a completely randomized design with a 2 × 3 factorial arrangement and 2 replicates, every cow underwent 2 of 6 treatments. Two sources of P4 [controlled internal drug release (1.9 g of P4) from Zoetis (São Paulo, Brazil), and Sincrogest (1.0 g of P4) from Ourofino (Cravinhos, Brazil)] and 3 types of processing, new (N), reused after autoclave (RA), and reused after chemical disinfection (RC), were used. After inducing luteolysis to avoid endogenous circulating P4, the cows were randomized in 1 of 6 treatments (1.9 g of N, 1.9 g of RA, 1.9 g of RC, 1.0 g of N, 1.0 g of RA, and 1.0 g RC). Cows were treated with the implants for 8 d and during this period blood samples were collected at 0, 2, 12, 24, 48, 72, 96, 120, 144, 168, and 192 h. Statistical analyses were performed using Proc-Mixed and the mean ± standard error of the mean P4 concentrations were calculated using the Proc-Means procedures of SAS 9.4 (SAS Institute Inc., Cary, NC). No interaction between treatments was observed. Comparing types of implant, average P4 concentrations during treatments were greater for 1.9 g than 1.0 g (1.46 vs. 1.14 ± 0.04 ng/mL). When types of processing were compared, average P4 concentrations did not differ between autoclaved and new inserts (1.46 vs. 1.37 ± 0.05 ng/mL; respectively), but both were greater than chemically disinfected implants (1.09 ± 0.04 ng/mL). Within 1.9-g P4 inserts, P4 concentrations from autoclaved implants were greater than new, which were greater than chemically disinfected (1.67 ± 0.06 vs. 1.49 ± 0.07 vs. 1.21 ± 0.05 ng/mL; respectively). For 1.0-g P4 implants, P4 concentrations from autoclaved did not differ from new, but both were greater than chemically disinfected (1.20 ± 0.08 vs. 1.24 ± 0.06 vs. 0.97 ± 0.05 ng/mL; respectively). In conclusion, the mean plasma P4 concentration in nonlactating Holstein cows was greater for 1.9 than 1.0 g of P4 and regardless of the type of implant, the autoclaving process provided greater circulating P4 in relation to chemical disinfection, and similar or greater P4 concentrations compared with a new implant.

Seasonality of reproduction in wild boar (Sus scrofa) assessed by fecal and plasmatic steroids

The collection of biological samples through non-invasive techniques represents one way of monitoring in vivo physiological changes associated with reproductive activity. Such techniques are particularly important for the study of animal species in the wild. The goals of this study were 1) to evaluate fecal progestogen (P), estrogen (E), and androgen (A) by means of radioimmunoassays, in male and female wild boars culled in the Piedmont, Italy area; 2) to compare them with plasmatic concentrations and the animals' reproductive status; and 3) to assess variations in reproductive seasonality between two populations of wild boars living in a mountainous vs. a plain habitat in Piedmont. The results demonstrate a positive correlation between fecal and plasmatic steroid concentrations (r=0.46, 0.58, and 0.45 for plasma P(4) and P, E(2) and E, and T and A; P<0.05). Moreover, high fecal levels of both P and E (>170 ng/g and >100 pg/g respectively) were found in 70.6% of pregnant sows and in none of the non-pregnant animals, thus supporting the use of this technique for detecting pregnancy status in wild boar. Similar birth patterns were displayed by the mountain and plain populations, but births peaked significantly only in the mountain population, in the spring (46%, P<0.05, vs. other seasons). A corresponding autumnal peak of plasma testosterone concentrations in males was displayed only by the mountain population (7.4 vs.<2.0 ng/mL in the other seasons, P<0.05). The correlation between fecal and plasmatic steroid concentrations obtained in this study supports the applicability of this non-invasive sampling technique for monitoring reproductive status in wild boar, thus enabling a more informed and correct management of the species.

Reduced fertility in high-yielding dairy cows: are the oocyte and embryo in danger? Part I. The importance of negative energy balance and altered corpus luteum function to the reduction of oocyte and embryo quality in high-yielding dairy cows

Fertility in high yielding dairy cows is declining, and there is increasing evidence to presume that oocyte and embryo quality are major factors in the complex pathogenesis of reproductive failure. In this report we present an overview of possible mechanisms linking negative energy balance (NEB) and deficiencies in oocyte and embryo developmental competence; specifically, in the high producing dairy cow. Changes in follicular growth patterns during a period of NEB can indirectly affect oocyte quality. The endocrine and biochemical changes, which are associated with NEB, are reflected in the microenvironment of the growing and maturing female gamete, and likely result in the ovulation of a developmentally incompetent oocyte. Even after an oocyte is successfully ovulated and fertilized, a full-term pregnancy is still not guaranteed. Inadequate corpus luteum function, associated with reduced progesterone, and probably also low insulin-like growth factor concentrations, can cause a suboptimal microenvironment in the uterus that is incapable of sustaining early embryonic life. This may partly account for the low conception rates and the high incidence of early embryonic mortality in high yielding dairy cows.

Measurement of Faecal Progesterone Metabolites and its Application for Early Screening of Open Cows Post-insemination

The present study investigated the changes of serum progesterone (P4) and its faecal metabolites in pregnant and non-pregnant cows (Expt 1) and the feasibilty of using faecal P4 metabolites for early screening of open cows post-insemination (Expt 2). In Expt 1, seven crossbred Holstein-Friesian (HF) cows were studied. Serum and faecal samples were collected once daily from the day of artificial insemination (AI) until 25 days after AI. In Expt 2, 27 crossbred HF inseminated cows were employed. Serum and faecal samples were obtained on the day of AI (day 0) and on days 19-22 post-insemination. Enzyme immunoassay measurements of serum P4 and faecal P4 metabolites were established. The low detection limit of the assay was 0.01 ng/ml and the amount of P4, resulting in a 50% reduction in the initial binding value, was 1.07 ng/ml. The intra- and inter-assay coefficients of variation were <8% and <14%, respectively. A positive correlation between the levels of serum P4 and faecal P4 metabolites was found in every single cow (r = 0.73-0.88, p < 0.001) and pooled data (r = 0.78, p < 0.001). The estimated value of faecal P4 metabolites at 100 ng/g of faeces was equal to the serum P4 levels of 1 ng/ml. The accuracies of pregnancy and non-pregnancy diagnosis based on the analyses of faecal P4 metabolites between day 0 and days 19-22 post-insemination, were 67% and 100%, respectively. In conclusion, the measurement of faecal P4 metabolites can be a potentially alternative method for early screening of open cows post-insemination with the same accuracy and precision, as measured by serum P4 assay.

Lessons from endocrine disruption and their application to other issues concerning trace organics in the aquatic environment

In the past 10 years, many thousands of research papers covering the many different aspects of endocrine disruption in the environment have been published. What has been learned from all this research? We have tried to reduce this very large volume of research into a relatively small number of "lessons". Hence, this paper is not a typical review, but instead it summarizes our personal opinions on what we consider are the major messages to have come from all this research. We realize that what has been a lesson to us may have been obvious from the outset to someone more knowledgeable on that particular aspect of the burgeoning field of endocrine disruption. In addition, it is inevitable that others will consider that we have "missed" some lessons that they would have expected to find included in our list. If so, we encourage them to submit them as responses to our paper. Our own lessons range widely, from the design and interpretation of data from fieldwork studies, through some key messages to come out of the very many laboratory studies that have been conducted, to issues around the sources and fates in the environment of endocrine-disrupting chemicals, and finally to the key role of sewage treatment in controlling the concentrations of these chemicals in the aquatic environment. Having (hopefully) learned our lessons, we have then applied them to the difficult issue of how best to approach future concerns about the potential impacts of other new and emerging contaminants (e.g., pharmaceuticals) on wildlife.