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At least 649 records · Page 36Linked to original sources
PubMed1997

Effects of using vasectomized bulls in artificial insemination practice on the reproductive efficiency of Italian buffalo cows.

The effects of the presence or absence of vasectomized male buffaloes on the reproductive efficiency of buffalo cows (n = 396) undergoing artificial insemination (AI) was studied on six farms owned and operated by a single consortium. Lactating animals were separated into two groups of various sizes on each farm and kept under semi-range conditions. Vasectomized bulls were present in one group at a bull/empty-cow ratio of 1:30. No bulls were present in the other group. Reproductive efficiency between the two groups over a period of 3.5 months was compared and evaluated on the basis of: 1) the number of spontaneous overt estruses associated with either feeble or intense signs of estrous behaviour; 2) the number of functional estrous cycles, i.e. estrous cycles with luteal phases defined as normal, based on specified progesterone concentrations in milk or blood plasma 8-10 days after estrus; 3) the number of consecutive functional estrous cycles in cases of induced estrus; and 4) pregnancy rate. Groups with bulls present demonstrated a significantly higher reproductive efficiency than groups without them. There was a higher incidence of spontaneous estrus (92 versus 69%; P < 0.01); spontaneous estrus of high intensity (62.2 versus 31.1%; P < 0.01); and higher incidence of functional estrous cycles following both spontaneous (65.8 versus 57.1%) and induced (77.0 versus 59.5%; P < 0.05) estrus. Exposure to vasectomised bulls also increased the incidence of consecutive functional estrous cycles (90.5 versus 68.1%; P < 0.01), and the pregnancy rate in cows inseminated at spontaneous (42.5 versus 18.9%; P < 0.01) or induced (51.1 versus 33.3%; P < 0.05) estrus. Overall pregnancy rate did not differ significantly between cows inseminated at induced or spontaneous estrus, although in the absence of bulls, pregnancy rate per AI was higher in cows inseminated at induced than at spontaneous estrus (33.3 versus 18.9%).

Animals↗
PubMed1997

Foetal loss in dairy goats: an epidemiological study in 515 individual goats.

Effects of various factors pertaining to the individual goat on the reproductive performance were studied during one season in 515 pregnant dairy goats from seven herds. A significant difference in the risk of foetal loss was found between the herds. Advanced age, difficulty in conceiving, low social status, pregnancy with > or = 3 foetuses and previous foetal loss were significantly associated with current loss. No association was found between foetal loss and the current goat index, milk production last year, daily milk production at the time of dry-off and the presence or absence of horns or dehorning of the goat. The risk of foetal loss was not related to mating with specific bucks. No indication of relationship between goats with foetal loss was found by pedigree analysis including the sire, dam and dam's sire. However, the incidence of foetal loss was significantly higher in daughters of does that had suffered reproductive loss than in daughters of does without such a loss. This suggests a maternal or genetic influence on the occurrence of foetal loss. Culling of goats suffering non-infectious abortion and of their surviving progeny therefore seems reasonable.

Animal Husbandry↗
PubMed1999

Reproduction management of tethered cows on Norwegian dairy farms.

Dairy farms in southern Norway were surveyed to obtain information regarding reproduction management in tied herds. A total of 1613 farms were included in the analyses. Reproductive performance during the main breeding period of the year (November 1 to February 28) was measured using the following dependent variables: calving to first service and last service interval, number of artificial inseminations per cow, non-return rate at 60 days, and calving interval. Culling for failure to conceive was found to be associated with longer calving to first service interval, more inseminations per cow and lower non-return rate. More inseminations per cow and lower non-return rate were also recorded in herds where breeding was close to calving. Oestrous checks late in the evening and frequent observations were associated with shorter calving to last service interval and shorter calving interval. Calving to last service interval was prolonged if the farmers were occupied with routine work while conducting oestrous checks. Manual rectal pregnancy testing was of little importance for reproductive efficiency in dairy herds with good breeding performance. More inseminations per cow occurred in herds where oestrous checks were conducted systematically 3 and 6 weeks after service. Calving to last service interval and calving interval were shorter when only one person was responsible for the herd breeding management.

Animal Husbandry↗
PubMed1987

Use of monoclonal antibodies for radioimmunoassay of water buffalo milk progesterone.

In order to standardize a radioimmunoassay of milk progesterone as a routine method for confirmation of oestrus and diagnosis of pregnancy in water buffalo, monoclonal antibodies against progesterone were produced. Hybridomas were prepared by fusing spleen cells from a Balb/c mouse immunized with progesterone 11 alpha-hemisuccinate-bovine serum albumin conjugate with the mouse myeloma cell line NS-1. Thirty wells out of 94 secreted anti-progesterone antibodies. Of the ten independent hybridomas derived, one (AF65) was suitable for the quantification of milk progesterone by radioimmunoassay. The tracer used in the assay was progesterone-11 alpha-hemisuccinate [( 2-125I]iodohistamine). The sensitivity of the assay was 50 pg/tube. The mean progesterone concentration at oestrus was 0.8 +/- 0.2 ng/ml increasing to 8.5 +/- 0.8 ng/ml 24 d later in pregnant animals.

Animals↗
PubMed2002

Behavioural and physical signs associated with oestrus and some aspects of reproductive performance in Fogera cows and heifers.

An investigation was carried out into the behavioural and physical signs of oestrus in 70 Fogera cows and heifers between December 1993 and May 1994 at Metekel Cattle Breeding and Improvement Ranch, Ethiopia. Retrospective information generated from records made between 1991 and 1994 was evaluated for some aspects of the reproductive indices. The mean +/- SD duration of oestrus (n = 136) was 10.6 +/- 4.5 h (range 2.2-21). Most oestruses (63.2%) started during the day (06:00-18:00). The incidence of oestrus was significantly affected by months (chi 2 = 21.86; p < 0.001). Among the physical signs, standing to be mounted was the most consistent indication (97.8%) of oestrus. About 12.5% of the cows in oestrus did not mount other cows. The retrospective study indicated that the mean interoestrus interval for 46 oestruses was 29.2 +/- 19.7 days. The average gestation length for 141 cows was 276 days. Continuous and careful observation of oestrus would reduce the reproductive wastage that arises from less pronounced heat periods and those occurring at night, especially for ranches that use artificial insemination and have a limited number of bulls.

Animals↗
PubMedDate not supplied

Effects of bull exposure and body growth on onset of puberty in Bunaji and Friesian x Bunaji heifers.

A total of ninety seven pre-pubertal Bunaji (BJ) and Friesian-Bunaji (FR x BJ) heifers were allotted randomly to two treatments groups for a period of 15 months. The treatment groups consisted of the followings: Mature Bull Exposure (MBE) and No Bull Exposure (NBE). Heifers were body condition scored and their live weights recorded on 28 days consecutive intervals. A heifer tactile stimulation in bull bio-stimulation. was considered to have attained puberty if she displayed oestrus, had a palpable corpus luteum with an associated P4 concentration > 1 ng x mL(-1). The onset of puberty was significantly earlier in MBE heifers (23.1 +/- 0.4 months) than NBE heifers (26.4 +/- 0.4 months). The mean ages at puberty for MBE-BJ, NBE-BJ, MBE-FR x BJ, NBE-FR x BJ were 24.3, 27.8, 22.1 and 25.0 months respectively. More MBE heifers (70.8%) attained puberty between 17 and 24 months of age than NBE heifers (18.3%) and on the same ages, more FR x BJ heifers (62.0%) than BJ heifers (25.5%). The mean live weight of MBE heifers at puberty (224.4 +/- 4.2 kg) was significantly lower than that of the NBE heifers (255.8 +/- 4.2 kg). The FR x BJ heifers attained puberty at a significantly higher live weight (270.2 +/- 4.2 kg) than the BJ heifers (228.6 +/- 4.2 kg). The use of a vasectomised bull especially in some elite farms that rely on artificial insemination services may be an effective management tool that can decrease age at puberty. More work is required to determine the relative contribution of visual, auditory, olfactory, pheromonal and tactile stimulation in bull biostimulation.

Age Factors↗
PubMed2000

Non-invasive monitoring of reproductive status in wild mongoose lemurs (Eulemur mongoz).

Endocrine profiles were investigated in wild and captive mongoose lemurs (Eulemur mongoz; Lemuridae) by analysing faecal progestagens and oestrogens. Oestrous cycle characterization was not possible, as most females appeared to conceive during the first oestrus of the breeding season. Conception was preceded by a pseudo-oestrus with no discernible luteal phase. Pseudo-oestrus and oestrus identification was possible by investigating the oestrogen:progestagen ratio. Pregnancy was reliably determined approximately 47 days after conception, when progestagen and oestrogen excretion increased above breeding season concentrations. Gestation was further characterized by high progestagen concentrations and a decline in oestrogen excretion 70-80 days after conception. Post partum, progestagens declined, but oestrogen excretion increased to exceed breeding season concentrations. In the wild group, a nulliparous daughter conceived while still a member of her natal group and aborted after 70-80 days of pregnancy at which time progestagens had declined but oestrogens remained high. Comparisons with other strepsirhine primates suggest that pseudo-oestrus followed by conception at first oestrus may be prevalent in lemurs. Gestational progesterone profiles vary between species, but a delayed increase in oestrogens during pregnancy could be common to all strepsirhines, although oestrogen levels during the final trimester of pregnancy differ between lemurs and lorises. Methodological investigations showed that prolonged storage of faeces in ethanol is viable and that the presence of undigested vegetable matter in the faecal pellets had no effect on the interpretation of hormone profiles.

Animals↗
PubMed1982

Enzymeimmunoassay of milk-progesterone: its application to oestrus confirmation and early pregnancy diagnosis in cattle.

A solid-phase enzymeimmunoassay (EIA) was developed for progesterone, based on horse radish peroxidase as the enzyme-label and Dasp (sheep anti-rabbit Ig, covalently linked to cellulose) for separation of antibody-bound and free hormone. The validity of the assay was substantiated in accordance with criteria for sensitivity, precision, accuracy and specificity; it is simple to perform and can be done in one day. Milk samples were taken on the day of A.I. (day 0) and on day 21 from 60 dairy cows which belonged to an artificial insemination (A.I.) station in the central part of Thailand. Conception rate (C.R.) after first A.I., as diagnosed by the milk-progesterone test, was 31.7 per cent. Based on rectal exploration on day 84-93 and on 'non-return' at 85 days. C.R. was 20.0 per cent and 23.3 per cent, respectively. All animals except one showed non-luteal phase progesterone levels at the time of A.I. It is concluded that low C.R. in these cows is not due to inseminations during the luteal phase of the oestrous cycle.

Animals↗
PubMed1986

Androgen receptors in brain and pituitary of female rats: cyclic changes and comparisons with the male.

The in vitro binding of a synthetic androgen, methyltrienolone ([3H]-R1881), to brain and pituitary (PIT) cytosol and nuclear extracts was determined in male and female rats. Purified cytosol was prepared from PIT or hypothalamic-preoptic area-amygdala (HPA) and incubated in the presence of 0.1 to 10 nM [3H]-R1881. Scatchard analysis revealed the presence of a single, saturable, high-affinity binding site in PIT cytosol with a dissociation constant (Kd) of 0.42 X 10(-10) M in females and 0.95 X 10(-10) M in intact males. The Kd of HPA cytosol was much less in castrated males [0.47 +/- 0.05 (SEM) X 10(-10)M, n = 7] and females (0.63 +/- 0.1 X 10(-10) M, n = 4) than in intact males (5.8 +/- 1.1 X 10(-10) M, n = 8). Treatment of castrated males with dihydrotestosterone (DHT) for 24 h (250 micrograms/100 g of body weight) increased the Kd of HPA cytosol only slightly (1.6 X 10(-10) M, mean of two replicates). Scatchard analysis of salt-extracted nuclear androgen receptor (ARn) showed a single, high-affinity binding site with similar Kd values in PIT and HPA of intact and castrated, DHT-treated male rats (PIT Kd = 7.3 X 10(-10) M, 9.3 X 10(-10) M; HPA Kd = 1.5 X 10(-9) M, 1.3 X 10(-9) M, respectively). Competition studies involving a range of several radioinert steroids revealed that the binding of [3H]-R1881 to cytosol (ARc) and nuclear extract was specific for androgen receptor when triamcinolone acetonide (10 microM) was added. The ARc and ARn levels were quantified in PIT, preoptic area (POA), hypothalamus (HT), amygdala, hippocampus, and cortex by single point estimation. Significantly (p less than 0.01) greater amounts of ARc were detected in PIT of ovariectomized females (32.7 +/- 2.9 fmol/mg of protein) than in that of orchidectomized males (22.33 +/- 1.6 fmol/mg of protein). The highest levels in the brain were seen in HT and POA. Pituitary ARc in females varied throughout the estrous cycle. Significantly (p less than 0.01) greater amounts were detected on estrus (45.8 +/- 2.2 fmol/mg of protein) and proestrus (39.0 +/- 1.9 fmol/mg of protein) than on diestrus (29.2 +/- 1.5 fmol/mg of protein). These data confirm the existence of specific receptors for androgen in male and female brain and PIT, and suggest an important role for androgen in the control of PIT hormone secretion in the female.

Animals↗
PubMed1991

Characterization of thymosin alpha 1 and beta 4 during the bovine estrual period: effects of elevated estradiol and progestin.

At present, there is a renewed interest in thymic function and its secretions in relation to endocrine control and reproductive function. In an initial experiment, 60 crossbred heifers (18-20 mo) were detected in estrus and assigned to control or FSH superovulatory groups. On Days 7-14 of the subsequent estrous cycle, FSH was administered for 5 days and prostaglandin F2 alpha (PGF2 alpha) was administered at 48 and 60 h after the initial FSH injection. Control animals received only PGF2 alpha injections between Days 9 and 15 of the cycle. Blood samples were collected from all animals at the time of PGF2 alpha injection and every 12 h thereafter to 72 h post PGF2 alpha injection. In a subsequent experiment, 103 crossbred heifers (16-18 mo) were superovulated with FSH and synchronized to estrus with PGF2 alpha administered 60 h after the initial FSH injection. Twenty-eight of the heifers received Norgestomet implants 12 h prior to the initial PGF2 alpha injection to inhibit the LH surge. Blood samples were collected from animals at 12-h intervals until the PGF2 alpha injection and every 6 h thereafter until 108 h post PGF2 alpha treatment. Although thymosin beta 4 concentrations did change over the estrual period, no differences were noted between control and superovulatory animals in the initial experiment even though estradiol concentrations were increased tenfold from the FSH stimulated ovary. In the second experiment, thymosin beta 4 and alpha 1 increased as the estrual period progressed and decreased (p less than 0.05) subsequent to the LH surge. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Action of a cyclopropenoid fatty acid on the corpus luteum of pregnant and nonpregnant ewes.

The effects of a cyclopropenoid fatty acid on luteal cell function were studied. In experiment 1, pregnant ewes were laparotomized on Day 18 of gestation and ewes with CL in both ovaries were unilaterally ovariectomized. Either 1.09 mg of an extract of Sterculia foetida seeds, containing 750 micrograms sterculic acid methyl ester (SA, n = 6), or 1.09 mg oleic acid methyl ester (OA, n = 6) was injected into the artery supplying the ovary bearing CL. Jugular blood was collected on Day 18 before surgery and daily thereafter until Day 30 of gestation or until detection of estrus, whichever occurred first. Serum was assayed for progesterone (P4) by RIA. In experiment 2, CL were removed from ewes on Day 10 of the estrous cycle and slices of luteal tissue were incubated in medium containing 145 ng/ml of S. foetida extract (100 ng/ml SA) or 145 ng/ml OA (control) for 90 min. Then tissue was washed and reincubated in medium containing 25 micrograms 22(R)-hydroxycholesterol/ml or 25 micrograms pregnenolone/ml for 120 min. Tissue plus medium was analyzed for P4. Injection of SA or OA on Day 18 of gestation reduced (p < 0.01) serum levels of P4 within 24 h; concentrations of P4 then remained low, and relatively constant, in six OA control ewes that were pregnant until Day 30 of gestation and in three SA-treated ewes that had nonviable fetuses on Day 30. Serum concentrations of P4 in SA-treated ewes were lower than those of control ewes (p = 0.009). The remaining three ewes injected with SA exhibited estrus within 3 to 5 days after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

The use of decision analysis to evaluate the economic effects of heat mount detectors in two dairy herds.

This paper reports a decrease in the interval from calving to conception in two commercial dairy herds, associated with the use of KaMaR Heat Mount Detectors. An economic analysis of the results uses a neoclassical decision theory approach to demonstrate that the use of heat mount detectors is likely to be profitable, with an expected net return of $154.18 per 100 calvings. The analysis demonstrates the suitability of a decision-theoretic approach to the analysis of applied research, and illustrates some of the weaknesses of "Classical" statistical analysis in such circumstances.

Animals↗
PubMed1978

Preparation of teaser bulls by dorsal scrotal penile deflection.

A simple, quick and reliable technique of preparing teaser bulls has been developed. Four Bos indicus aged between 1 year 6 months and 2 years were subjected to this method by deflecting their penes backwards about 2 to 3 cm posterior and dorsal to the attachment of the scrotum. No serious postoperative complications were recorded. The sexual behaviour and libido of the bulls did not change after subjecting them to this technique.

Animals↗
PubMed1980

Assessment of vaginal impedance measurements as an indicator of oestrus in cattle.

A study was made in cattle of the variation of vaginal impedance with respect to the placement of probe, time after insertion, and stages of the oestrous cycle. Impedance values were lowest and least variable when determined in the ventral sector of the vaginal fornix. Allowing the probe time to warm up improved results. Vaginal impedance declined by approximately 30% during pro-oestrus, oestrus and metoestrus when compared with dioestrus. The time at which the lowest values were reached varied between animals, in 2 cases being a day before oestrus, in another 2 on the day of oestrus, and for 1, the day after oestrus. The method described was not suitable for determining the peak of behavioural oestrus.

Animals↗
PubMed1988

Calving rates of Brahman and Brahman-cross cows to fixed-time insemination after treatment with pregnant mare serum gonadotrophin and intravaginal progesterone.

In 2 experiments involving 151 non-lactating and 107 lactating Brahman or Brahman-cross cows, the effects of progesterone treatments (PRID) of 2 durations (7 v 14 days) and injections of pregnant mare serum gonadotrophin (PMSG) at 3 doses (O v 375 v 750 IU) were examined. All cows were inseminated with frozen/thawed semen 54 to 58 and 70 to 74 hours after PRID removal. Calving rates of non-lactating cows (38%) were unaffected by breed or treatment but were higher in previously cyclic than acyclic cows (44% v 19%, P less than 0.025) and in cows which exhibited oestrus after treatment (52% v 23%, P less than 0.001). Calving rates of lactating cows were not affected by these factors but were affected by treatment; PMSG produced no significant effect after a 7-day PRID treatment (33% overall) but increased calving rates after 14-day PRID treatments (22% v 46% v 37% for 0, 375 and 750 IU respectively, P less than 0.10). Comparisons of calving rates of lactating cows treated with 14-day PRID and PMSG and artificially inseminated, and untreated naturally mated cows, showed that treatment significantly increased the proportion of cows conceiving in the first 35 days of the mating period (50% v 23%, P less than 0.025). The results show that treatment with PRID for 14 days and PMSG can overcome post-partum anoestrus in lactating Brahman and Brahman-cross cows leading to significant reductions in the calving to conception interval.

Animals↗