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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

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

Control of Estrus in Gilts and Primiparous Sows

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The Effect of Ambient Temperature on Conception and Milk Performance in Breeding Holstein Cows

The aim of this study was to identify the effect of ambient temperature and season of the year on conception difficulties in Holstein cattle. The experiment was conducted on the School farm in Žabčice. Data were collected from July 2016 to January 2017. Experimental population counted 263 breeding Holstein cows, which were inseminated during the observation period. Results of this study confirmed the effect of temperature and season on conception rates in dairy cows. In winter season, successful conception was recorded in 56.36 % of cows in average ambient temperature 1.48 oC, in summer season the conception rate was only 40.43 % in average daily temperature 18.96 oC. A more detailed analysis revealed the highest conception rates in the dairy cows in January (88.24 %) and February (91.67 %). On the contrary, the worst results were recorded in September (22.73 %) and October (28.57 %). Evaluation of conception rate according to ambient temperature intervals showed best results for the temperatures below 5 oC. A part of the study was also evaluation of an association between daily milk yield and conception rate. This hypothesis cannot be conclusively confirmed, because milk yield was mostly similar in both groups (pregnant and non-pregnant) on the days of insemination. The effect of lactation order and mean daily milk yield on the conception rate in cows was not confirmed.O

Učinak primjene melatonina prije teljenja na izlučivanje mlijeka tijekom laktacije u mliječnih krava

This study evaluated the effects of melatonin administration 60 days prior to expect calving (drying-off period) on milk yield during the next lactation. Sixty dairy cows were treated with subcutaneous melatonin implants during summer (n=30) or winter (n=30) period. Another 60 animals were not treated and served as the control. There were no differences in the average milk yield between treated and untreated animals (44.5±3.7 and 44.8±5.0 kg/day for melatonin and control cows, respectively). There was an effect of season with a higher winter milk yield than in summer (43.8±5.0 and 47.1±3.0 kg/day for melatonin and control groups, respectively). The interaction between melatonin and season showed no significant effect; however, during winter, milk yield tended to be higher (P=0.06) in control cows than in melatonin treated cows (45.3±3.7 and 49.2±3.0, respectively). This study indicates that treatment with melatonin prior to calving did not modify milk yield during the following lactation. Only a tendency for a reduction in milk yield during winter was observed in melatonin treated cows.U ovom istraživanju procjenjivan je učinak primjene melatonina 60 dana prije očekivanog teljenja (razdoblje isušivanja) na proizvodnju mlijeka tijekom kasnije laktacije. Šezdeset mliječnih krava tretirano je potkožnim implantatima melatonina tijekom ljetnog (n=30), odnosno zimskog (n=30) razdoblja. Drugih 60 životinja nije tretirano i one su poslužile kao kontrola. Nije bilo razlika u prosječnoj proizvodnji mlijeka između tretiranih i netretiranih životinja (44,5±3,7 kg/ dan u krava tretiranih melatoninom, odnosno 44,8±5,0 kg/dan u kontrolnih krava). Postojao je učinak sezone, pri čemu je proizvodnja mlijeka bila veća zimi u odnosu na ljeto (43,8±5,0 kg/ dan u krava tretiranih melatoninom, odnosno 47,1±3,0 kg/dan u kontrolnoj skupini). Interakcija između melatonina i sezone nije pokazala značajniji učinak, ali tijekom zimske sezone proizvodnja mlijeka u kontrolnih krava bila je veća (P=0,06) u odnosu na krave tretirane melatoninom (45,3±3,7 u kontrolnoj skupini, odnosno 49,2±3,0 u krava tretiranih melatoninom). Ova studija ukazuje da tretman melatoninom prije teljenja ne mijenja proizvodnju mlijeka tijekom kasnije laktacije. Primijećena je samo tendencija smanjenja proizvodnje mlijeka u zimskoj sezoni u krava tretiranih melatoninom

Effect of melatonin administration prior to calving on milk secretion in the next lactation in dairy cows

This study evaluated the effects of melatonin administration 60 days prior to expect calving (drying-off period) on milk yield during the next lactation. Sixty dairy cows were treated with subcutaneous melatonin implants during summer (n=30) or winter (n=30) period. Another 60 animals were not treated and served as the control. There were no differences in the average milk yield between treated and untreated animals (44.5±3.7 and 44.8±5.0 kg/day for melatonin and control cows, respectively). There was an effect of season with a higher winter milk yield than in summer (43.8±5.0 and 47.1±3.0 kg/day for melatonin and control groups, respectively). The interaction between melatonin and season showed no significant effect; however, during winter, milk yield tended to be higher (P=0.06) in control cows than in melatonin treated cows (45.3±3.7 and 49.2±3.0, respectively). This study indicates that treatment with melatonin prior to calving did not modify milk yield during the following lactation. Only a tendency for a reduction in milk yield during winter was observed in melatonin treated cows

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.)

Nota introduttiva n. 11 – ottobre 2012

Storia e satira. Una relazione complessa La satira è una pratica discorsiva complessa e multiforme, una forma d’espressione “di confine”, a cavallo tra diversi media, linguaggi e obiettivi. Questo carattere si evidenzia a partire dall’incerta definizione del termine che, in prima battuta, può essere ricondotto ai mitici satiri romani (sàtyros) – la cui natura demoniaca e priapesca rimanda alla sfera della lascivia, dell’aggressività e del sovvertimento delle regole – ma anche alla lanx satura..

Efficacy of serial ultrasonographic examinations in predicting return to play in agility dogs with shoulder lameness

The aim of this study is to investigate the use of shoulder ultrasound as a method of predicting the likelihood of returning to competition in agility dogs with shoulder teno-muscular injuries after a standardised rehabilitation protocol. Thirty-two agility dogs with a clinical and ultrasonographic diagnosis of shoulder teno-muscular injury were included in a prospective study with physical and ultrasound examinations at the time of diagnosis (T0) and at two (T2), four (T4) and six (T6) months; during this period, the dogs received rehabilitation treatments. The endpoint of the study was to obtain information regarding participation in agility competitions 12 months after diagnosis, based on telephone interviews with the owners. The clinical lameness score (CLS) and the ultrasound lesion score (ULS) were used as outcome measurements. The CLS indicated partial recovery from a shoulder injury at T2 (78%), while the ULS indicated no satisfactory recovery at T2 in any patient. At 4 months, the CLS alone was not a valuable predictor of full recovery from a shoulder injury in agility dogs. Relative Risk indicated that, at T2, ultrasound was 23.8 times more valuable in identifying a shoulder lesion as compared to clinical lameness score (CLS), and it was 2.53 times more valuable at T4