Effect of repeated low doses of gonadotropin-releasing hormone on the secretion of luteinizing hormone and follicle-stimulating hormone, and ovarian function in dairy cows suffering from anovulation type I

The aim of the study was to evaluate the effect of repeated low doses of gonadotropin-releasing hormone (GnRH) agonist buserelin once a day for 5 days on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release, and ovarian function in dairy cows with anovulation type I. The study was conducted on 10 anovulatory Polish Holstein-Friesian cows. Cows in Group 1 (n = 5) received 4 µg of buserelin intramuscularly. once a day for 5 days. Control cows from Group 2 (n = 5) received saline. Concentrations of progesterone, FSH, and LH in the blood were analysed using radioimmunoassay (RIA). Ovarian structures were monitored weekly after the end of treatment by ultrasound for 4 weeks. Injections of buserelin increased FSH and LH concentrations. Release of FSH and LH was largely variable, but there was significant (P < 0.001) interaction between time and treatment during all treatment days. The number of follicles in the treatment group was significantly greater (P = 0.029) than in the control group on day 5, the diameter of follicles on day 12 was also larger (P < 0.01) in treated than in control cows. Ovulation occurred in 4 of the 5 treated cows, but only in 1 of the control cows in the 40 days after treatment. In conclusion, repeated low doses of GnRH analogue buserelin once a day for 5 days may increase the concentration of FSH and LH in dairy cows with anovulation type I.

Use and adequacy of non-pregnancy diagnosis in cow. Which future?

In cattle, early detection of gestation is very important from an economic and management point of view in all types of farming. However, due to the poor efficiency of oestrus detection, it is essential to determine non-pregnant cows as early possible, in order to minimize the inter-insemination interval, thus de facto, reducing herd open days. Direct and indirect gestation diagnostic methods have been developed with the aim of improving the reproductive performance of the herd. Today, the most accurate method for making an early diagnosis of gestation from 28-30 days post insemination is B-Mode ultrasound. In recent years, indirect methods have included techniques that allow non-pregnant cows to be identified with a minimum margin of error, the most widely utilized of which is the Color-Doppler. This technique is rapidly becoming established for the diagnosis of non-pregnancy that allows the identification of non-pregnant animals earlier compared the pregnancy diagnosis. Some limitations of this technique in dairy cow have been presented.

The Influence of Intravaginal Gestagens Treatment on the Morphological Features and Endometrial Steroid Hormone Receptors Content during Anestrus Type II in Dairy Cattle

Background: Gestagens are the most widely used therapy in anestrus type II. The aim of this research is to evaluate the effectiveness of the vaginal progesterone inserts therapy in anestrus type II in cows. Methods: The study was conducted on 33 cows. Progesterone (PR) and estrogen (ER) receptors expression in endometrium was assessed on a molecular level based on mRNA tissue expression. Additionally, blood 17ß-estradiol and progesterone levels were evaluated. Results: A decrease in mRNA expression of A and B PR and ER α was noted in treated and untreated animals. In the treated group, an increase of ERß mRNA expression was observed, while a decreased was found in untreated animals. There was increased PR, ERα and ß expression in endometrial tissue in treated cows, and decreased expression of these factors in untreated cows. In the treated group, recurrence of ovarian cyclicity was noted in 52% of animals and pregnancy was obtained in 34.8% of them, while in the untreated group, recurrence did not occur. In the control group, spontaneous recurrence of ovarian cyclicity was not observed. An increase of PR expression was correlated with increased proliferation of endometrial cells. Conclusions: It seems likely that the endometrium is well developed and ready for placentation after removing the exogenous source of progesterone and preventing the recurrence of cyclicity of ovaries.

Investigation of negative energy balance and postpartum anoestrus in an intensive dairy farm from the Chinese province of Heilongjiang

The aim of this investigation was to determine the relationship between postpartum anoestrus and negative energy balance in an intensive dairy farm from the Heilongjiang Province, China. At 14 to 21 d after parturition, 100 cows were randomly selected and their plasma indices, including β-hydroxybutyric acid, non-esterified fatty acid, and glucose were measured. Cows were assigned to a positive energy balance group (n = 37) and a negative energy balance group (n = 36) based on their β-hydroxybutyric acid concentrations (> 1.20 mmol/l). The two groups of cows were examined by B-mode ultrasonography and rectal examination from 60 to 90 d after parturition to identify the ovarian status of oestrous and anoestrous animals. The incidences of negative energy balance and positive energy balance were 49 and 57%, respectively, from14 to 21 d after parturition. From 60 to 90 d after parturition, 94.4% of the negative energy balance group were in anoestrus and 5.6% were in oestrus, while 62.2% of the positive energy balance group were in anoestrus and 37.8% were in oestrus. Furthermore, the proportion of inactive ovaries in the negative energy balance group was 61.8%. In conclusion, the negative energy balance is an important factor causing inactive ovaries in high-yielding dairy cows.

Causes of declining fertility in dairy cows during the warm season

In the Northern Hemisphere, from June to September and in the Southern Hemisphere from December to March, there are periods of reduced fertility (sub-fertility) in dairy cows that are described as summer infertility. Several factors contribute to sub-fertility during this time, such as ambient temperature, humidity and photoperiod. During the warm season there is a reduction in feed intake that may compromise the energy balance of the cow and/or induce an imbalance in the activity of the hypothalamo-hypophyseal-ovarian axis. These factors reduce the reproductive performance of the cow and compromise the quality of oocytes, embryos and corpora lutea. This paper reviews current knowledge on the metabolic and endocrine mechanisms that induce summer infertility and describe their effects on follicle, oocyte and embryo development in dairy cows.

Plasma oxidative stress biomarkers and progesterone profiles in a dairy cow diagnosed with an ovarian follicular cyst

This study was conducted to examine the oxidative stress biomarkers in a cow diagnosed with a follicular cyst in her left ovary. Progesterone (P4) and plasma oxidative stress status was measured in 13 Holstein cows after synchronization of oestrus with controlled internal drug release (CIDR) and prostaglandinF2α (PGF2α) protocol. The presence and size of ovarian structures were monitored by transrectal ultrasound at 4 hourly intervals. Of the 13 cows, 12 were monitored until ovulation was detected and recorded, whereas one cow failed to ovulate and developed a follicular cyst. Oxidative stress biomarkers; reactive oxygen metabolites (ROMs), biological antioxidant potential (BAP), oxidative stress index (OSI), glutathione (GSH), ceruloplasmin and advanced oxidation protein products (AOPP) were measured in the cystic cow and compared to those of the 12 ovulated cows and are referred to as higher or lower if they are outside the mean ± standard error of mean of those of ovulated cows. The cystic cow had lower ROMs and OSI between 36 and 84 h after PGF2α injection and at 9 h, from 36 to 60 h after PGF2α injection respectively. On the other hand, antioxidant (BAP and GSH) was higher in the cystic cow compared to her ovulated herd mates. The observed imbalance between oxidant and antioxidant might have disrupted the physiological events for ovulation to occur, leading to cystic ovarian disease.

Postpartum anestrus in dairy cattle

Fertility of the postpartum period is negatively influenced by the incidence of anestrus. The latter condition is characterized by the absence of estrous behavior, which may be an indication of suboptimal conditions (e.g., inadequate peripartum nutrition) or pathologic conditions (e.g., chronic debilitating diseases or uterine and ovarian diseases). Although initiation of ovarian follicular growth in the postpartum period is generally not affected, subsequent development (deviation) and the fate of the dominant follicle are the primary factors that affect reestablishment of ovarian cyclicity. Anestrus can be classified based on the three functional states of follicular development; that is, follicle emergence, deviation, and ovulation. Prevention of anestrus is preferable to treatment and can be achieved in part by maintaining a healthy periparturient period. To better understand the etiology of anestrus and its prevention, research is urgently needed in the following three areas: the role of peripartum disease conditions that influence reproduction, genes involved in ovulation, and the influence of proteins (e.g., leptin) that appear to be important links between metabolic signals and the neuroendocrine axis.

An inventory of the ethnoveterinary practices for reproductive disorders in cattle and buffaloes, Sargodha district of Pakistan

AIM OF THE STUDY

This study was conducted to document the ethnoveterinary practices (EVPs) used for the treatment and/or management of reproductive disorders of cattle and buffaloes.

MATERIALS AND METHODS

The information was collected using rapid and participatory rural appraisal techniques through interviews and focused group discussions with 217 traditional veterinary healers (TVHs) over a period of 16 months.

RESULTS

The use of 66 plant species was documented for the treatment of reproductive disorders in the two dairy species. Most frequently reported (>or=20 times) plants represented Apiaceae, Poaceae, Pedaliaceae, Linaceae, Arecaceae, Brassicaceae, Malvaceae, Zingiberaceae, Rosaceae, Cannabaceae, Fabaceae, Moraceae, Rubiaceae and Mimosaceae families. All the documented plant species were indigenous to the study area. Genital prolapse, retention of fetal membranes, silent estrous/delayed puberty, anestrous, dystokia associated with incomplete cervical dilatation and retention of lochial discharge were the frequently reported reproductive disorders. Some of the plants were reported to be used in more than one condition. Materials other than plants used for the treatment of these disorders included camel milk, butter and butter fat, minerals, eggs, organic matters, chemical substances and meat preparations. These materials were used either alone or as adjunctive therapy.

CONCLUSION

Richness of EVPs in the study area and extensive variation in the doses, methods of preparation, indications, and claims regarding efficacy of plants for various disorders merit controlled studies for their validation.

Field trial on the relationship of blood metabolites and body condition score with the recurrence of luteal activity in Estonian Holstein cows

Associations of body condition scores and blood metabolites, measured before calving and at different periods during early lactation, with recurrence of luteal activity were investigated in a 250-head commercial dairy farm during a 4-year period (1999-2002). The study was conducted on 48 dairy cows (60 lactations) with average 305-day milk yield of 8149 kg per cow. Blood samples taken 1-14 days before calving and 1-14, 28-42 and 63-77 days after calving were analysed for aspartate aminotransferase, glucose, ketone bodies, triglycerides, non-esterified fatty acids and cholesterol. Milk progesterone (P(4)) profiles (samples collected twice a week, P(4) levels measured in whole milk by enzyme immunoassay) were used to evaluate the interval from calving to first luteal response, P(4) >5 ng/ml, and the interval from calving to first normal cycle. The MIXED procedure of the sas system was used to study the association of investigated parameters. A higher concentration of ketone bodies before calving was associated with shorter interval to recurrence of first normal cycle (P = 0.007) and tended to be related to shorter interval from calving to first luteal response (P = 0.071). A lower prepartum aminotransferase activity showed a tendency to be associated with shorter interval from calving to first luteal response (P = 0.084). Results suggest metabolic status up to 2 weeks prepartum to be related to the resumption of postpartum luteal activity in Estonian Holstein dairy cows.

Leptin concentrations in relation to energy balance, milk yield, intake, live weight, and estrus in dairy cows

The objective of this study was to describe fluctuations in leptin concentrations during late pregnancy and lactation and to investigate how those fluctuations are related to energy balance, milk yield, milk components, dry matter intake, live weight, first postpartum luteal activity, and first observed estrus during lactation. Live weight, dry matter intake, energy balance, and milk yield were measured weekly on 304 primiparous Holstein cows for the first 80 d of lactation. The first postpartum luteal activity was determined by measuring milk progesterone, and independently, first observed estrus. For measuring leptin concentrations from 30 d before until 80 d after calving, blood samples were taken at 2-wk intervals at a fixed time of the day after milking but before feeding. Leptin concentrations were high during pregnancy and declined to a nadir at parturition. It seems that leptin concentrations reflect the state of energy balance during lactation; plasma leptin concentrations were lower in cows with a mean negative energy balance during lactation. Those cows usually produced more milk, consumed less feed, and had a lower live weight compared with cows having a mean positive energy balance. The recovery of leptin concentrations from the leptin nadir at parturition seemed to depend on the extent and duration of the negative energy balance, thus probably on the amount of fat that was re-accumulated. Although there was lack of a relationship between leptin and first postpartum luteal activity, higher leptin concentrations associated with shorter intervals to first observed estrus might indicate a relationship between leptin and expression of estrus.