To what extent does photoperiod affect cattle reproduction? Clinical perspectives of melatonin administration

The seasonality of reproduction in most mammals is dictated by photoperiod, temperature and nutrition. Melatonin, mainly synthesized in the pineal gland, is generally accepted as the active mediator of photoperiod responses including reproduction. While non-pregnant heifers and cows show continuous sexual activity and are therefore not seasonal breeders, it has been suggested that photo-periodicity may influence the appearance of puberty in heifers and the onset of parturition. Further, the light/dark ratio may influence endocrine patterns of gestation and a shorter light period correlates with the incidence of twin pregnancies. This review considers specific aspects of the effects of photoperiod and melatonin on reproduction in dairy cattle and discusses the clinical applications of melatonin

Effect of utilization of single or double prostaglandin administration within an ovsynch fixed-time artificial insemination protocol during summer season in dairy cows

This study investigated the fertility of dairy cows during summer season after treatment with a single or double PGF2α in a progesterone (P4)-based Ovsynch protocol for fixed-time artificial insemination (FTAI). The data were compared to a treatment effectuated during winter season. Two groups of 60 dairy cows each were randomly assigned on day 60 post-partum to single PGF2α or double PGF2α group. At removal of the P4 treatment the single PGF2α group received a single dose and the double PGF2α group received two doses of PGF2α at 24 hours apart. In each group, 30 cows were treated during the summer (June, July and August) and 30 cows during the winter (December, January and February) season. During summer season a double PGF2α dose did not influence pregnancy rate at FTAI but improved cumulative pregnancy rate 60 days after FTAI (43% vs 69% for single PGF2α and double PGF2α administration, respectively; P<0.05). During winter season the single or double PGF2α administration did not modify PR or cumulative PR. In conclusion, during summer the utilization of a double instead of single PGF2α treatment into a P4-based Ovsynch-FTAI protocol did not increase pregnancy rate at FTAI but improved cumulative pregnancy rate

Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle

While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing.This research was funded by “Fondo Locale per la Ricerca-FIL 2020/2021” University of Parma, Italy (coordinator F.D.R.)

Crosstalk between uterine serpin (SERPINA14) and pregnancy-associated glycoproteins at the fetal-maternal interface in pregnant dairy heifers experimentally infected with Neospora caninum

Infection with Neospora caninum is the leading cause of abortion in cattle. In cows naturally infected with N caninum, plasma concentrations of pregnancy-associated glycoproteins (PAG) 1 and 2 indicate fetal-placental well-being, whereas an excess of progesterone in the second trimester of gestation has been related to high abortion rate. The immunosuppressive action of progesterone on the uterus during gestation has been attributed in part to the uterine serpins (SERPINA14). This study examines expression patterns of the genes SERPINA14, PAG, and PAG2 at the fetal-maternal interface in dairy heifers experimentally infected with N caninum during the second trimester of pregnancy, when most abortions takes place in natural conditions. Irrespective of infection, expression of SERPINAI4 was higher, and expression of PAG1 and PAG2 lower, for intercaruncular endometrium than for caruncles or cotyledons. Cotyledonary tissues showed the highest expression of both PAG genes but lowest expression of SERPINAI4. The expression of SERPINAI4 was significantly higher in intercaruncular endometrium of control dams than for infected animals, pointing to potential disruption of modulation of maternal immune function during infection. Dramatically reduced SERPINAI4 was particularly apparent in infected dams with aborted fetuses. There was also a negative association between N caninum antibody titers with SERPINAI4 and PAG expression in infected animals, further suggesting that N caninum infection downregulates the uterine immunosuppressive function of SERPINAI4.This study was supported by a grant from the Spanish MINECO (AGL2012-39830-C02-01/02) and FEDER. Ramón Mur-Novales was awarded an FPI grant by the Spanish Ministry of Science and Innovation, MICINN, BES-2013-063215. The authors thank Ana Burton for editorial assistance, the farmers who provided the experimental animals and the staff of CReSA for their help with managing the animals, and Dr. L.M. Ortega-Mora (SALUVET, Universidad Complutense, Madrid, Spain), for the Neospora isolate

Molecular method for the characterization of Coxiella burnetii from clinical and environmental samples: variability of genotypes in Spain

BACKGROUND: Coxiella burnetii is a highly clonal microorganism which is difficult to culture, requiring BSL3 conditions for its propagation. This leads to a scarce availability of isolates worldwide. On the other hand, published methods of characterization have delineated up to 8 different genomic groups and 36 genotypes. However, all these methodologies, with the exception of one that exhibited limited discriminatory power (3 genotypes), rely on performing between 10 and 20 PCR amplifications or sequencing long fragments of DNA, which make their direct application to clinical samples impracticable and leads to a scarce accessibility of data on the circulation of C. burnetii genotypes. RESULTS: To assess the variability of this organism in Spain, we have developed a novel method that consists of a multiplex (8 targets) PCR and hybridization with specific probes that reproduce the previous classification of this organism into 8 genomic groups, and up to 16 genotypes. It allows for a direct characterization from clinical and environmental samples in a single run, which will help in the study of the different genotypes circulating in wild and domestic cycles as well as from sporadic human cases and outbreaks. The method has been validated with reference isolates. A high variability of C. burnetii has been found in Spain among 90 samples tested, detecting 10 different genotypes, being those adaA negative associated with acute Q fever cases presenting as fever of intermediate duration with liver involvement and with chronic cases. Genotypes infecting humans are also found in sheep, goats, rats, wild boar and ticks, and the only genotype found in cattle has never been found among our clinical samples. CONCLUSIONS: This newly developed methodology has permitted to demonstrate that C. burnetii is highly variable in Spain. With the data presented here, cattle seem not to participate in the transmission of C. burnetii to humans in the samples studied, while sheep, goats, wild boar, rats and ticks share genotypes with the human population