Arylsulphatase A activity and sulphatide concentration in the female rabbit oviduct are under physiological hormonal influence

Summary Oviduct samples of female rabbits in different phases of the reproductive cycle were analysed to establish the role of sex steroid hormones in the regulation of sulphatide concentration and arylsulphatase A activity. In addition to biochemical procedures, histochemical techniques were used to localize both enzyme activity and the natural substrate. The plasma concentrations of progesterone and 17β-oestradiol were determined by radioimmunoassay (RIA). The findings show that the parameters examined undergo considerable changes during the different phases of the reproductive cycle. Oestrogens exert an inducing action on arylsulphatase A activity, while progesterone inhibits it. Fluctuations of the catabolic arylsulphatase activity condition the sulphatide concentration, which reaches maximum values at the eighth post-ovulatory day when progesterone dominance is consolidated. In this phase of the reproductive cycle, thin-layer chromatography confirms the presence not only of larger quantities of sulphatides, but also of all other lipid fractions.     

Enzyme immunoassay of progesterone in the feces from beef cattle to monitor the ovarian cycle

The present study was undertaken to measure fecal progesterone concentration of beef cattle using antibody against authentic progesterone and to examine whether this method can monitor the ovarian cycle in beef cattle. Rectal fecal samples collected from 14 beef cattle were mixed with 6 ml of 100% methanol and shaken for 15 min. After centrifugation, supernatant was extracted with petroleum ether followed by an enzyme immunoassay (EIA) for progesterone. Specificity of the assay was examined by HPLC separation of fecal solution followed by the EIA in each fraction. The present assay identified only progesterone but not other metabolites in the feces sample that was extracted with petroleum ether. Sensitivity of the assay was estimated to be 0.0055 ng/ml (0.11 ng/g). Coefficient variations of intra- and inter-assay were 9.6-10.9% and 10.8-16.6%, respectively. Recovery rates ranged between 73 and 84%. Patterns in the fecal progesterone concentrations during the ovarian cycle were almost parallel to the plasma concentrations. A significant positive correlation was established between the fecal and plasma progesterone concentrations in individual animal (r=0.59-0.84, P<0.001, n=10) as well as pooled data (r=0.70, P<0.001, n=65). Fecal progesterone concentrations of day 0 (showing the nadir of concentration) of the ovarian cycle were less than 50 ng/g, which increased significantly toward day 9 (P<0.01). From days 14 to 18, there was significant reduction of fecal progesterone concentration (P<0.01). Ovarian cycles had at least 48 ng/g (mean=74 ng/g) of difference between minimum and maximum fecal progesterone concentrations. All cattle at days 9, 11 and 14 had higher fecal progesterone concentrations by more than 20 ng/g compared with day 0. These results suggest that the present EIA is suitable to measure the progesterone in cattle feces and can monitor ovarian cycle.     

Progesterone determinations and clinical examinations of reproductive organs in purebred and crossbred female Zebu cattle

Five experiments were undertaken to investigate variation in progesterone concentrations as related to the collection and handling of samples of milk and blood, to determine reference values for progesterone and to evaluate clinical findings in relation to progesterone data from pure- and crossbred Zebu cattle reared in the Peruvian tropics. Whole-milk progesterone concentrations obtained from 12 Holstein x Nellore pregnant cows at hourly intervals over a 24-h period were highest immediately after milking; this peak was followed by a sharp drop over the next 3 h. Milk-fat content from 28 Brown Swiss x Nellore pregnant cows increased from 2.4% before milking to 6.7% afterwards (P < 0.05), whereas progesterone concentrations in whole milk increased from 18.4 to 59.5 nmol/1 (P < 0.05). Progesterone concentrations in fat-free milk were stable, with the exception of the fore-milk sample, which was lower than subsequent samples collected during milking (P < 0.05). Blood samples collected from 23 purebred, pregnant Nellore cows, were divided into four aliquots, and plasma and serum were harvested periodically over the next 120 h of storage at +4 degrees C, or in the shade at ambient air temperatures. The results indicate that blood samples can be stored unseparated at both temperatures studied for up to 3 h without severe loss of progesterone. Milk samples collected at different intervals during the luteal phase of the estrous cycle and during early and mid-pregnancy from crossbred cows showed no significant differences in progesterone concentrations between Days 9 to 13 of the cycle and Days 9 to 13 of gestation. Progesterone levels during advanced gestation were higher (P < 0.05). Out of 2,607 clinical examinations, the level of agreement between palpatory findings and progesterone determinations was 95.6 and 81.9% in diagnosing non-luteal and luteal structures, respectively. Significant differences in the level of agreement between palpators were found (P < 0.01). It is concluded that milk samples, preferably composite milk or strippings, must be consistently collected at the same stage of milking, and that centrifugation of blood samples should be done as soon as possible and not later than 3 h after collection.     

Adrenal and white cell count responses to chronic stress in gestating and postpartum females of the viviparous skink Egernia whitii (Scincidae)

This study investigates the relationships between plasma corticosterone concentrations and white cell counts in captive females of the viviparous lizard Egernia whitii during two phases of the reproductive cycle. Gestating and postpartum females were captured in the field and held in the laboratory for 4 weeks. Plasma corticosterone and progesterone concentrations and white blood cell counts were examined in blood samples taken at capture and after 24 h, 1 week, and 4 weeks in captivity. At 24 h after capture, plasma corticosterone concentrations in both groups had increased significantly compared with initial values but then returned to initial concentrations after 1 week in captivity and remained low in the 4 week samples. Plasma progesterone concentrations remained elevated in the gestating females until the week 4 sample, just prior to parturition. The hormone data suggest that capture and captivity did not represent a significant long-term stressor to these animals. The increase in plasma corticosterone concentration was associated with heterophilia in the differential leucocyte count in both groups of females. Lymphocyte numbers decreased only in gestating females, suggesting that reproductive status may influence the interaction between adrenal activity and immune function.     

Reproductive cycles in Bos indicus cattle

Several studies using transrectal ovarian ultrasonic scanning in Bos taurus (B. taurus) cattle and more recently in Bos indicus (B. Indicus) females evaluated the reproductive cycles of heifers and cows under different conditions. In general, B. indicus cattle have more follicles and more follicular waves during the estrous cycle and ovulate from smaller follicles than B. taurus. Consequently B. indicus females have smaller corpora lutea and it is assumed circulating concentrations of estradiol and progesterone are also less. However, these findings may vary depending on the nutritional status and regimen in which the animals are managed. Moreover, there are significant differences between B. taurus and B. indicus regarding follicle size at the time of deviation of the dominant follicle. These differences in ovarian function between B. indicus and B. taurus, e.g. greater antral follicle population are, probably, the main reasons for the great success of in vitro embryo production programs in Zebu cattle, especially in Brazil.     

Plasma progesterone profiles and fertility status of anestrus Zebu cattle treated with norgestomet-estradiol-eCG regimen

Zebu cattle are notorious for poor fertility characterized by late maturity and long intercalving intervals attributed to a variety of factors, including genetic, nutritional and climatic. The aim of the present investigation, therefore, was to induce fertile estrus in acyclic pubertal heifers and postpartum anestrous Zebu cows by hormonal intervention. Pubertal Hariana and Sahiwal anestrous heifers (n=51) and postpartum cows (n=55) were either assigned a placebo (controls, N=6 for each breed and parity) or treated with 10-d norgestomet (3 mg) subcutaneous ear implants, with an initial injection of 3 mg, im norgestomet + 5 mg estradiol valerate, followed by 500 IU eCG at implant withdrawal (NOR-treated groups). Jugular venous plasma samples were obtained from a total of 28 animals (controls : 4 heifers and 4 cows; NOR-treated : 12 heifers and 8 cows) on Days 0 (implant insertion), 3, 7, 9 and Day 10 (implant withdrawal), every 12 h on Days 11 and 12, and then once daily on Days 17, 24 and 31. All the samples were assayed for progesterone. Almost all (97%) heifers and 81% cows were induced to estrus, the majority (92% heifers and 79% cows) within 120 h of implant removal. Synchrony of the induced estrus was better in cows, but interval to estrus and estrus duration were significantly longer in heifers (P<0.05). Post-treatment fertility, based on Day 28 nonretum rate, first service, and overall conception rates, was better in heifers (78.9, 60.5 and 73.7%, respectively) than cows (77.1, 48.6 and 62.9%, respectively), but the differences were significant only for the overall pregnancy rate (71.8% for heifers and 51.2% for cows; P<0.05). Low pre-treatment plasma progesterone values (<0.5ng/mL) were consistent with ovarian inactivity, confirming the true anestrus status of experimental animals. Controls failed to exhibit estrus and maintained low progesterone concentrations throughout the study. In treated animals, high progesterone values from Day 17 onwards suggested ovulatory estrus. These early luteal phase progesterone concentrations in nonpregnant (P=0.06) and nonpregnant, nonretum (P<0.05) animals were low in comparison with those of pregnant animals. Good fertility resulting from breeding according to estrus, inspite of variable intervals to estrus and estrus duration, advocates its advantage over fixed-time insemination in norgestomet-treated anestrous Zebu cattle.     

Incidence of trypanosomes in settled Fulani cattle in the Anambra State, southern Nigeria

The incidence of trypanosomes in Fulani Zebu cattle settled in the Anambra State in southern Nigeria for at least three continuous years was found significantly higher than incidence in northern Nigeria. Despite this situation the cattle in the Anambra State were reported to show better reproductive performance, generally looked healthier and more robust than cattle in northern Nigeria. Presence of tsetse flies or trypanosomes per se appears not to constitute a complete hindrance to cattle production in a given zone. The result was discussed.     

Analysis of genetic diversity of domestic cattle in East and Southeast Asia in terms of variations in restriction sites and sequences of mitochondrial DNA

There are three major groups of domestic cattle in East and Southeast Asia: European cattle, Zebu cattle, and Bali cattle. Ten restriction enzymes were used to analyze restriction site variants in the mitochondrial DNA (mtDNA) in 178 individuals belonging to these three groups of cattle. The results indicate that each of the three groups has mtDNA with a specific haplotype. The sequence of the mitochondrial gene for cytochrome b in representative haplotypes of Zebu and Bali cattle was determined and was compared with that of European cattle in the literature. We calculated 51 pairwise nucleotide sequence differences between European and Zebu cattle and 91 between European and Bali cattle. Our results suggest that ancestral populations of Asiatic domestic cattle may have diverged into two lineages—Bali and European plus Zebu—more than 3 million years ago, and then the European and Zebu groups diverged more than 1 million years or so before domestication occurred.The sequences of mitochondrial genes for cytochrome b from Zebu cattle, Bali cattle and Water buffalo will appear in the DDBJ, EMBL and GenBank nucleotide sequence databases, with the following accession numbers: D34635, D34636 and D34637.     

Progesterone levels and relationship with the diagnosis of a corpus luteum by rectal palpation during the estrous cycle in Zebu cows

To assess the accuracy of rectal palpation for detecting functional luteal tissue during the estrous cycle in Zebu cattle, 20 mature non-lactating Indobrazil cows were palpated twice weekly for 7 1/2 weeks. Blood samples were drawn for progesterone analyses at each palpation. Circulating serum progesterone levels were below 0.5 ng/ml from days 0-4 (Day 0 = day of estrus); they increased thereafter, reaching maximum levels of 3.1 ng/ml on days 9 and 10. Values declined sharply to less than 0.5 ng/ml on day 18. Regardless of the stage of the estrous cycle in 71.3% of the cases (117 out of a total of 164 observations) the circulating progesterone levels corresponded to the results of rectal examination. The criteria to assess this relationship were that the presence of CL as determined by rectal palpation would be accompanied by levels of progesterone higher than 0.5 ng/ml, whereas absence of CL would be accompanied by levels less than 0.5 ng/ml. The correlation was significantly higher (P<0.05) on days 5-17 (77.9%) than on days 0-4 (57.5%) and 18-20 (65%). To assess the correlation of both rectal examination and progesterone levels with the stage of the estrous cycle, we expected that on days 0-4 and 18-20 no palpable CL and progesterone levels less than 0.5 ng/ml would occur, whereas on days 5-17 palpable CL and progesterone levels higher than 0.5 ng/ml would be found. On this basis, a correlation of 45% (18 out of 40 observations) between expected and observed values was found on days 0-4, 76% (79 out of 104) on days 5-17 and 60% (12 out of 20) on days 18-20 of the estrous cycle. Of the total of 55 observations which fell outside the expected values, 71% was due to a wrong diagnosis of CL; 14.5% was due to progesterone levels higher or lower than the expected values, and 14.5% to both laboratory and rectal palpation findings.     

Habitat use by cattle affects host contact with lone star ticks (Acari: Ixodidae)

The location of Zebu, British, and Zebu x British cattle in tick-infested plots from March through September 1986 was compared with the location of Amblyomma americanum L. in the same plots. In April, May, and June, Zebu cattle spent less time (9.3-19.4%) in tick-infested quadrats than British (44.4-63.9%) or Zebu-British (49.0-69.3%) cattle. In the same months, the probability that A. americanum would contact Zebu cattle (1.5-19.6%) was significantly lower than for British (34.7-41.7%) or Zebu-British (30.2-56.9%) cattle. In April, May, June, and September, the probability that A. americanum detaching from cattle would drop into a quadrat presumed to be habitable for ticks was significantly lower for Zebu cattle (4.0-29.9%) than for British (64.9-72.6%) or Zebu-British (48.1-78.7%) cattle.     

Investigation of X- and Y-specific single nucleotide polymorphisms in taurine (Bos taurus) and indicine (Bos indicus) cattle

Initially, domesticated African cattle were of taurine type. Today, we find both African Bos taurus and Bos indicus cattle, as well as their crossbreeds, on the continent of Africa and they all share the same set of African taurine mitochondrial DNA haplogroups. In this study, we report genetic variation as substitutions and insertions/deletions (indels) on both the X and Y chromosomes, and use the variation to assess hybridization between taurine and indicine cattle. Six African cattle breeds (four Sanga breeds, including Raya Azebu, Danakil, Caprivi, Nguni; and two Zebu breeds, including Kilimanjaro Zebu and South Kavirondo Zebu) were screened for six new X-chromosomal markers, specifically three single nucleotide polymorphisms and three indels in the DDX3X (previously DBX ) and ZFX genes, and five previously identified Y-chromosomal markers in the DDX3Y (previously DBY ) and ZFY genes. In total, 90 (57 bulls and 33 cows) samples from the African breeds were analysed. We identify five diagnostic haplotypes of indicine and taurine origins on both the X and Y chromosomes. For each breed, the level of indicine introgression varies; in addition to pure taurine, indicine and hybrid X-chromosome individuals, recombinant X-chromosome variants were also detected. These markers are useful molecular tools for assessing the level of indicine admixture in African cattle breeds.     

Identification of a DNA methylation point in the promoter region of the bovine CYP21 gene

The CYP21 (steroid 21-hydroxylase) gene is involved in the synthesis of steroid hormones. Bov-A2 is a retroposon that is common in ruminant genomes. The promoter region of bovine CYP21 contains a short interspersed nucleotide element of Bov-A2, which overlaps a putative Sp1 binding site. We looked for RFLP/HpaII polymorphism in the Bov-A2 element in bovine Zebu breeds by PCR-RFLP, and examined whether polymorphism in this element is associated with methylation. Among DNA samples from 135 Brazilian Zebu breed cattle, we identified an RFLP/HpaII polymorphism (T/C), which, based on a restriction methylation-sensitive assay employing HpaII and isoschizomer MspI enzymes (methylation-sensitive and -non-sensitive enzymes, respectively), appears to be a DNA methylation point. This is the first report of this polymorphism and on DNA methylation in the bovine CYP21 promoter region in Brazilian Zebu cattle.     

A comparative study of gastrointestinal nematode egg output in N'Dama, Zebu and N'Dama x Zebu crossbred cattle.

Strongyle faecal egg output was estimated in N'Dama, Zebu and N'Dama x Zebu crossbred (F1) cattle. N'Dama cattle showed a significantly lower prevalence of strongyle infection, as measured by faecal egg output, than F1 (P < 0.01) and Zebu (P < 0.001) cattle. In strongyle-infected animals, mean egg output was also significantly lower in N'Damas (P < 0.03) than in Zebus. A previous trypanosomiasis infection did not affect the results. The presence of a natural resistance trait to strongyle infection in N'Dama cattle is postulated.     

Plasma estradiol, testosterone, and progesterone levels during the ovulatory cycle of the skate (Raja erinacea)

Amounts of estradiol, testosterone, and progesterone in plasma were measured during the reproductive cycle of female Raja erinacea. Estradiol titers correlated directly with follicle size in females undergoing ovarian recrudescence, while highest concentrations were found in females with preovulatory follicles. These data indicate that as follicles grow, their steroidogenic capacity increases. In mature, nonspawning females, titers of estradiol and testosterone varied markedly. Progesterone was not detected in peripheral plasma of skates that did not produce eggs during the observation period. In females producing eggs, estradiol and testosterone predominated during the follicular phase of each spawning cycle. While estradiol and testosterone were elevated, progesterone was not detectable in the peripheral circulation. As ovulation and formation of capsules approached, plasma estradiol and testosterone declined to near baseline levels. Circulating progesterone rose sharply two days before encapsulation of ovulated eggs and remained elevated for only two days. On the day of encapsulation, concentrations of plasma progesterone had fallen to nearly baseline levels. Progesterone titers remained low throughout egg retention and oviposition. These measurements demonstrate that progesterone titers are elevated at specific times during the reproductive cycle of the skate and clearly suggest that progesterone is critically involved in events occurring at ovulation, encapsulation, and possibly oviposition.     

Serum progesterone profiles of zebu cattle (Bos indicus) in relationship to conception and repeat breeding after artificial insemination

Sixty-four zebu cows, comprised mainly of Bunaji cattle aged between 3 and 7 years old, were involved in an intensive artificial insemination programme. The study was conducted during the breeding period (May-October), and cows were inseminated with freshly prepared Friesian semen when they stood to be mounted by the vasectomised bull or herdmates. Fertility was measured by serum progesterone (P(4)) concentrations and pregnancy diagnosis by rectal examination post-insemination. From the records of oestrus detection and P(4) profiles of cattle following breeding, 39 oestrous cycle lengths were classified into short, normal and long cycles. The mean duration for short, normal and long oestrous cycles were 15.6+/-2.0, 21.5+/-1.5 and 29.5+/-2.5 days, respectively. Mean inter-oestrus intervals between the treatment groups were not different. The percentage frequency distribution was 48.7% for normal oestrous cycles. The short oestrous cycle lengths of 11-17 days were observed in 12.8% of the cases, while 38.5% of the cases of oestrus returns had long luteal phases with oestrous cycle lengths of 26-32 days.Out of the 64 cows, 48.4% conceived to the first breeding while 18.8% conceived to the second breeding. Five and nine cows became acyclic after the first and second breeding, respectively, constituting 22. 0%. Cows that displayed irregular oestrous cycles (repeat breeders) constituted 10.9%. Average number of services per conception was 1.3. Serum P(4) is of practical value in monitoring ovarian activity in cattle and in the identification of acyclic and repeat breeder cows. Repeat breeder cows could be investigated by a combination of radioimmunoassay and clinical examination of the ovaries and reproductive tract. In cattle management, it is economical and profitable to diagnose pregnancy early after insemination so that cows which fail to conceive may be rebred.     

Blood groups of Nigerian cattle. Comparative aspects

Cattle, red cell antigens as determined by a selected battery of 37 reagents characterizing genes at 10 major loci in 101 Zebu, 63 Ndama and 78 Muturu from Nigeria, have been compared with corresponding red cell antigens of a total of 257 Bos taurus cattle in Norway, the Netherlands, France, Spain, Hungary and USA. The Zebu cattle, represented by the three subtypes Gudali, Red Bororo and Shuwa Arab, showed the highest number of red cell factors. Ndama and Muturu cattle had a significantly lower number of blood factors than the Zebu cattle. The lowest number of blood factors were found in European Bos taurus breeds.     

Blood groups of Nigerian cattle. Comparative aspects

Cattle, red cell antigens as determined by a selected battery of 37 reagents characterizing genes at 10 major loci in 101 Zebu, 63 Ndama and 78 Muturu from Nigeria, have been compared with corresponding red cell antigens of a total of 257 Bos taurus cattle in Norway, the Netherlands, France, Spain, Hungary and USA. The Zebu cattle, represented by the three subtypes Gudali, Red Bororo and Shuwa Arab, showed the highest number of red cell factors. Ndama and Muturu cattle had a significantly lower number of blood factors than the Zebu cattle. The lowest number of blood factors were found in European Bos taurus breeds.     

Pulsatile secretion of LH during the periovulatory and luteal phases of the oestrous cycle in the Père David's deer hind (Elaphurus davidianus)

Changes in the secretion of LH during the oestrous cycle were studied in 5 tame Père David's deer in which ovulation was synchronized with progesterone implants and prostaglandin injections. Plasma LH concentrations were measured in samples collected at 15-min intervals for a 36-h period, starting 16 h after the removal of the progesterone implants (follicular phase), and for a further 10-h period 10 days after the removal of the progesterone implants (luteal phase). In all animals, there was a preovulatory surge of LH and behavioural oestrus which occurred at a mean time of 59.6 h (+/- 3.25) and 69 h respectively following implant removal. LH pulse frequency was significantly higher during the follicular phase (0.59 +/- 0.03 pulses/h) than the luteal phase (0.24 +/- 0.2 pulses/h), thus confirming in deer findings from research on domesticated ruminants. There were no significant differences between the follicular and luteal phases in mean plasma LH concentrations (0.57 +/- 0.09 and 0.74 +/- 0.13 ng/ml) or mean pulse amplitude (0.99 +/- 0.14 and 1.05 +/- 0.21 ng/ml) for the follicular and luteal phase respectively. The long interval from the removal of progesterone to the onset of the LH surge and the absence of a significant difference in mean LH concentration or pulse amplitude in the follicular and luteal phases resemble published data for cattle but differ from sheep in which there is a short interval from luteal regression to the onset of the surge and a marked increase in LH pulse amplitude during the luteal phase.     

Reproductive and hormonal patterns in the African green monkey (Cercopithecus aethiops).

The results of breeding Cercopithecus aethiops under time-mated laboratory conditions and analysis of total estrogen, progesterone, and LH concentrations in plasma during the menstrual cycle and plasma estrogen and progesterone concentrations during pregnancy indicate that this species is a suitable alternative for the rhesus monkey as a model for investigations of reproductive function in man.     

Relationships among milk progesterone,concentrate allocation,energy balance,milk yield and conception rate in Norwegian cattle

Relationships among milk progesterone, concentrate allocation, energy balance (EB), milk yield and conception rate were studied in 146 lactations in 94 moderate yielding cows. All animals were of the dual purpose breed Norwegian cattle, and were monitored through their first and second lactations. The cows were assigned three different concentrate allocations and had free access to grass silage. Energy balance was estimated by subtracting energy required for maintenance and lactation from energy intake. Milk progesterone concentration was determined three times weekly from calving until pregnancy. The cumulative progesterone concentration was calculated as area under the progesterone curve for the first three luteal phases postpartum. The conception rate increased linearly by rising milk progesterone for values of cumulative progesterone in the lowest third of the range, whereas the likelihood of conception did not differ between milk progesterone concentrations within the upper two-thirds. This implies that the progesterone values were below a threshold value for optimal reproductive success in one-third of the services performed in this study. Milk progesterone concentrations during the third luteal phase postpartum were low when the high-energy diet was fed. Negative EB was associated with reduced values for milk progesterone during the third luteal phase in second parity cows. Likewise, milk yield was inversely related to progesterone levels during both the first and third luteal phases postpartum in second parity cows. Energy balance was higher and milk yield lower during peak lactation among second parity cows that conceived compared to cows that remained open after the first artificial insemination. The present study have demonstrated an association between likelihood of conception and the energy coverage in Norwegian cattle. This relationship is possibly mediated through progesterone deficiency.