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Biomedical subjects

J F Roche

Publications and source records attributed to J F Roche.

At least 73 records · Page 4Linked to original sources
PubMed1994

Infrequent structures in cattle oocytes.

Uncommon and controversial structures in cattle oocytes were studied in dominant and subordinate follicles of unstimulated Bos taurus and zebu (Bos indicus), and in FSH-stimulated B. taurus cattle, before or after administration of cloprostenol. Growing oocytes were very rare in follicles more than or equal to 5 mm in diameter. For the first time, special vesicles that may be involved in cortical granule synthesis were observed. Classical rough endoplasmic reticulum was very rare in unstimulated oocytes, but was seen at superovulation. Vacuolation of the nucleolus was a common feature in dominant oocytes that were collected after cloprostenol injection, except in superovulated cattle. Annulate lamellae were very rare or absent in oocytes of B. taurus, while they were more frequent in zebu oocytes.

Animals↗
PubMed1994

Prostaglandin F2 alpha immunization of prepubertal beef heifers: effects of conjugate dose and timing of immunization relative to puberty on the onset of puberty and subsequent ovarian function.

Fifty-six prepubertal Hereford cross Friesian heifers were assigned to seven treatment groups: (1) primary (day 0) and booster (day 41) using 10 mg human serum albumin (HSA) (control); (2) primary and booster (day 41) immunizations using 3.3 mg prostaglandin F2 alpha PGF-HSA conjugate; (3) primary and booster (day 83) using 3.3 mg PGF-HSA; (4) primary and booster (day 210) using 3.3 mg PGF-HSA; (5-7) as in treatments 2-4 except 10 mg PGF-HSA were used. Plasma progesterone concentrations were used to determine the onset of puberty and the presence of a corpus luteum (CL); plasma PGF antibody titres were determined at 28-day intervals. There was no effect (P > 0.05) of conjugate dose or booster interval on mean antibody titres and there was no interaction between them. However, heifers in the 83- and 210-day booster treatments had higher (P < 0.05) peak antibody titres than heifers in the 42-day booster treatments. Puberty was delayed in 40% (16/40) of PGF-immunized heifers and 40% (16/40) of heifers formed persistent CL after puberty. Overall, eight of the heifers with delayed puberty also formed a persistent CL. There was a positive correlation between mean titre and onset of puberty but not with duration of persistent CL.

Animals↗
PubMed1994

Prorenin and active renin concentrations in ovarian follicular fluid increase after the LH peak in superovulated heifers.

1. The aim was to analyse the in vivo variations with time of prorenin and active renin and their relationship to steroid hormones in ovarian follicular fluid during follicular growth in heifers. 2. Thirty one beef heifers were assigned to two groups after oestrous synchronization: an unstimulated and a follicle-stimulating hormone (FSH)-treated (superovulated) group. Within each group, animals were slaughtered at different times of the follicular phase of the oestrous cycle. Ovarian follicular fluids were aspirated and analysed for the concentrations of active renin, prorenin, oestradiol-17 beta (E2) and progesterone (P4). 3. Prorenin and active renin concentrations in follicular fluid remained constant until the luteinizing hormone (LH) peak, after which time they increased four- and two-fold, respectively, in superovulated heifers. 4. In follicular fluid, prorenin and active renin correlated negatively with oestradiol and E2/P4 ratio but positively with progesterone during follicular growth in superovulated heifers. Prorenin also correlated negatively with oestradiol and E2/P4 ratio in unstimulated heifers. 5. The increase of renin concentrations in ovarian follicles after the LH peak and the correlations to steroid hormones suggest an important role of the ovarian renin-angiotensin system in bovine follicular growth and maturation.

Animals↗
PubMed1994

Effect of the presence of male and female flockmates on reproductive activity in ewes.

Four experiments were carried out to determine the effect of the presence of ewes and rams on the reproductive state of ewes. In Expt 1, the breeding season of ewes kept with a vasectomized ram ended later (April 18 +/- 8 days; mean +/- SEM) than that of ewes isolated from rams (6 March +/- 7 days; P < 0.01). In Expt 2, the end of the breeding season was later (5 May +/- 6 days; P < 0.05) and the onset of the next breeding season earlier (29 September +/- 2 days; P < 0.001) in ewes maintained with rams, compared with ewes isolated from rams (14 April +/- 7 days and 1 November +/- 2 days, respectively). There was no difference in the timing of, or variation in, reproductive transitions between ewes maintained either as individuals or in groups. In Expt 3, all ewes exposed to artificial short days from the date of the winter solstice and interrupted with 35 long days in spring resumed cyclicity (median date, 7 September; range, 59 days). Most ewes (seven of nine) exposed to short days from the date of the winter solstice and isolated from other ewes did not resume cyclicity in the following 11 months. In contrast, all ewes resumed cyclicity (median date, 19 October; range, 144 days) when exposed to short days but housed in social contact with other ewes that became reproductively active in early September; however, the onset of cyclicity was later than in ewes exposed to long days (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effect of exogenous progesterone on superovulatory response in heifers inseminated with fresh or frozen semen.

Superovulation in cattle normally involves the administration of gonadotrophins at specific times of the oestrous cycle, followed by the induction of luteolysis and insemination with high quality semen. The first aim of this experiment was to examine the effect of supplementary progesterone when used in conjunction with porcine FSH (pFSH) to induce superovulation in heifers. The methods compared were PGF2 alpha given at mid-cycle or a progesterone-releasing intravaginal device (PRID) inserted at different phases of the cycle. The second aim was to determine whether site of insemination or use of fresh or frozen semen affected embryo production. A factorial design was used involving 185 beef heifers. The main factors were (i) synchronization methods (PGF2 alpha or PRID); (ii) semen type (fresh or frozen); (iii) insemination regimens (involving two inseminations and variations in the sites) and number of straws used (one or two) at the second insemination. Eight injections of pFSH were given twice a day for 4 days starting either on days 9, 10 or 11 of the oestrous cycle or on the fourth day after insertion of a PRID. Heifers were checked for oestrus, inseminated twice and embryos were recovered on day 7 of the superovulated cycle. There was no difference between heifers given either PRID or PGF2 alpha in the oestrous response (93% versus 96%), number of ovulations (15.9 +/- 1.11 versus 13.4 +/- 1.06), large follicles (2.5 +/- 0.24 versus 2.3 +/- 0.23) or embryos recovered (9.1 +/- 0.77 versus 9.1 +/- 0.74).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Immunization of bull calves with a GnRH analogue-human serum albumin conjugate: effect of conjugate dose, type of adjuvant and booster interval on immune, endocrine, testicular and growth responses.

Bull calves were immunized with GnRH analogue-human serum albumin (HSA-Cys-Gly-GnRH) conjugate to determine the effects of dose, adjuvant type and interval between primary and booster injections on plasma testosterone and LH concentrations, and testes and body growth. Friesian bull calves aged between 8 and 10 weeks (n = 72) were blocked according to age and weight and, within block, randomly assigned to 12 treatment combinations (n = 6 per treatment combination) in a 3 x 2 x 2 factorial plan. Main effects were (i) conjugate dose (0.0, 0.1 or 1.0 mg HSA-Cys-Gly-GnRH), (ii) adjuvant (diethylaminoethyl-dextran or non-ulcerative Freund's adjuvant), and (iii) interval between primary (day 0) injection and booster injection (day 28 or 56). Plasma testosterone and LH concentrations and antibody titres were determined in blood samples collected at 14 day intervals during the experiment (140 days). Testicular measurements were taken in situ every 28 days. Antibody titres (% binding at 1:160 dilution) were > or = 10% 28 days after booster injection and remained high for 140 days in 47 of 48 GnRH-immunized bulls. The mean titre was higher (P < 0.05) in response to the 1.0 mg dose compared with the 0.1 mg dose (37.7% versus 29.6% binding, respectively; pooled SED 2.55%). Mean LH and testosterone concentrations were reduced (P < 0.05) in immunized animals compared with controls. However, the 1.0 mg dose decreased mean testosterone concentrations by a greater extent (P < 0.001) than either the 0.1 mg or 0.0 mg doses. Testes length and depth, and scrotal circumference were decreased (P < 0.001) in immunized animals compared with controls; however, the 1.0 mg dose decreased (P < 0.001) testes parameters to the greatest extent. There was no effect of conjugate dose on average daily gain in body mass. It is concluded that (i) dose of conjugate, type of adjuvant and interval between primary and booster injections affected antibody titres, (ii) the use of 0.1 or 1.0 mg of HSA-Cys-Gly-GnRH decreased LH and testosterone concentrations, and testicular development throughout the experiment, without adversely affecting body growth, and (iii) an effective protocol is 1.0 mg GnRH-HSA conjugate, given in the adjuvant diethylaminoethyl dextran, with a primary-booster interval of 56 days.

Adjuvants, Immunologic↗
PubMed1994

Selection, dominance and atresia of follicles during the oestrous cycle of heifers.

This study examined the correlation between measurement of follicle growth by ultrasound, and measurement of intrafollicular ratios of oestradiol and progesterone concentrations and the serum concentrations of FSH during selection, dominance and atresia or ovulation of dominant follicles in heifers. Heifers were ovariectomized on days 0 (before LH surge), 1 (after LH surge, preovulation), 1 (postovulation), 3, 6 and 12 of the oestrous cycle. Blood samples were collected at 4-6 h intervals. After ovariectomy all follicles > or = 5 mm were measured and follicular fluid was aspirated. Follicles were classified by size according to ultrasound (F1, largest; F2, second largest; F3, all remaining follicles > or = 5 mm) and by the ratio of oestradiol:progesterone concentrations. During the follicular phase, a single dominant oestrogen-active follicle increased in diameter while serum concentrations of LH increased and FSH decreased (P < 0.05). On day 1 (after LH surge, preovulation), serum LH and FSH decreased to pre-surge concentrations (P < 0.0001), while follicle size and intrafollicular progesterone concentration increased and oestradiol concentration decreased (P < 0.05). A dominant nonovulatory follicle, classified as oestrogen-active on days 1, 3 and 6 and oestrogen-inactive on day 12, increased in size from day 1 to day 7 and lost dominance during days 10-12, coincident with the growth of multiple oestrogen-active follicles. The serum FSH concentration increased transiently (P < 0.05) before each new wave of dominant follicular growth. The overall correlation of ultrasound measurements of follicle diameter with measures of follicle size after ovariectomy was high.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Association between the duration of dominance of the ovulatory follicle and pregnancy rate in beef heifers.

After luteolysis, subluteal concentrations of progesterone or treatment with a synthetic progestagen result in an extended period of dominance (persistence) of the dominant follicle in cattle. Two experiments studied (1) the relationship between the duration of dominance of the ovulatory follicle and pregnancy rate and (2) the ability of a persistent dominant follicle to ovulate and form a normal functioning corpus luteum. In Expt 1, beef heifers were either untreated (n = 30) or given a synthetic progestagen implant (3 mg norgestomet) for 12 days starting on day 16 of their cycle (n = 32). The mean duration of dominance of the ovulatory follicle differed (P < 0.05) between treated and control heifers (10.8 +/- 1.2 and 3.3 +/- 0.8 days, respectively) and 20 of 26 control and 7 of 30 treated heifers were diagnosed pregnant 28 days after artificial insemination (P < 0.01). In Expt 2, on the first day of dominance of the second dominant follicle, heifers received either a PGF2 alpha analogue alone (controls; n = 18), or prostaglandin and a norgestomet implant for 6 (T6; n = 19) or 10 days (T10; n = 20). Increases in the duration of dominance of the second dominant follicle (controls, 4.1 +/- 0.2 days; T6, 8.6 +/- 0.2 days; T10, 12.1 +/- 0.2 days; P < 0.05) resulted in a decrease in pregnancy rate (controls, 14 of 16; T6, 11 of 19; T10, 0 of 13; P < or = 0.05). Progesterone concentrations on days 7 and 12 and the area of luteal tissue on day 12 after artificial insemination were not different (P > 0.05) between treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Active immunization against prostaglandin F2 alpha: effect of conjugate dose and booster interval on antibody titers and estrous behavior in postpubertal beef heifers.

To optimize the prostaglandin F2 alpha (PGF) immunization protocol (conjugate [PGF-human serum albumin; PGF-HSA] dose and immunization regimen) to achieve prolonged suppression of estrous behavior (EB) in beef heifers, 56, 14-mo-old cyclic heifers were assigned (n = 7 per treatment) to eight treatments: 1) 3.3 mg of PGF-HSA on d 0 (single); 2) 3.3 mg of PGF-HSA on d 0 and 28 (booster; B); 3) as (2) except on d 0 and 55; 4) as (2) except on d 0 and 83; and 5 to 8) as in Treatments 1 to 4 except using 10 mg of PGF-HSA. The adjuvant was diethylaminoethyl-dextran, and duration of the experiment was 170 d. Heifers were checked twice daily for EB. A persistent corpus luteum (CL) was considered present when progesterone (P4) was > or = .5 ng/mL for > or = six consecutive samples (every 3 to 4 d). Data were analyzed using ANOVA for a factorial plan. All heifers produced plasma antibody titers (samples every 2 wk) against PGF (peak range: 7 to 84% binding at 1: 1,250). There were no effects (P > .10) of conjugate dose and no interactions between dose and immunization regimen for any variable; therefore, data were combined across dose. Mean and peak titers were greater (P < .05) in heifers in 55- and 83-d B treatments than those in single immunization and 28-d B treatments. Overall, 48/55 heifers formed a persistent CL (41/41 for B heifers). In the single, and 55- and 83-d B treatments, 23/42 heifers formed persistent CL in response to single/primary immunization. There was no difference between immunization regimens in duration (133 +/- 4.4 d) of persistent CL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Chromatin and microtubule morphology during the first cell cycle in bovine zygotes.

Chromatin and microtubule configurations during the first cell cycle of bovine zygotes were analyzed by DNA staining and microtubule immunolocalization using an IVM/IVF system and oocytes matured and fertilized in vivo, in order to investigate the origin of the active centrosome and to characterize the nuclear and the cytoplasmic changes following bovine fertilization. Our results suggest that the paternal centrosome is active during early zygotic development, forming a conspicuous sperm aster soon after fertilization. We also report that polyspermy in bovine eggs, leads to the formation of numerous sperm asters with different degrees of association with the chromatin. The maternal structures in both monospermic and polyspermic zygotes can be lost or degenerate. Consequently, these cells may resume the first cell cycle as androgenotes, very often with several types of mitotic activity taking place in different regions of the cell cytoplasm at the same time. As indicated by a comparison of monospermic and polyspermic fertilization rates to rates of development, it is possible that some androgenetic embryos cleave and develop to the blastocyst stage.

Animals↗
PubMed1993

The effects of once or twice daily injections of pFSH on superovulatory response in heifers.

Follicle stimulating hormone (FSH) is a glycoprotein hormone with a short half-life and has to be given twice daily for 3-4 days to induce superovulation in heifers. Since such a regimen is time consuming we compared the ovulatory response and yield of embryos in heifers following superovulation with either once or twice daily injections of pFSH for 4 days during the mid-luteal phase of a synchronized estrous cycle or during a prolonged luteal phase in heifers which had been immunized against prostaglandin F2alpha (PG). In Experiment 1, crossbred heifers (n = 42) previously actively immunized against a PG immunogen were superovulated in a 2 (cyclic or persistent corpus luteum) x 2 (once or twice daily injection) factorial plan. The heifers were superovulated with 75 units pFSH, which was injected subcutaneously once (22.5, 22.5, 15 and 15 units per day) or twice daily (9.3 units per injection) for 4 days. In Experiment 2, cyclic crossbred beef heifers (n = 80) were superovulated using pFSH which was given randomly to heifers once daily subcutaneously (T1) or twice daily intramuscularly (T2) using the same daily dose of 9, 7, 5, and 3 mg per day. Estrus was induced in all heifers in both experiments using 500 mug and 250 mug Cloprostenol 12 hours apart on the third day of pFSH injections. All heifers were inseminated twice with frozen-thawed semen at 12 and 24 hours after the onset of standing estrus or at 56 and 72 hours after the first PG if estrus was not observed. Embryos were recovered at slaughter and graded on a scale of 1 to 5 (1 = excellent, 5 = degenerated). Data were recorded for the number of corpora lutea (CL), large (>/=10 mm) and medium (5-9 mm) follicles, number of embryos recovered and embryo morphology. Data were analyzed by least squares analysis of variance procedures. In Experiment 1, there was no difference in ovulation rate between main effects. Fewer embryos were recovered from heifers with a persistent corpus luteum (pCL) and injected once daily (1.71+/-.75 vs 5.75+/-1.27) than from any other group. Heifers with pCL yielded lower (P < 0.05) numbers of freezable embryos than cyclic animals, regardless of injection regimen. In Experiment 2, T2 heifers had a significantly higher number of CL (16.4+/-1.7 vs 7.7+/-1.7; P = 0.0003), large follicles (4.1+/-0.5 vs 2.8+/-0.5; P = 0.04), medium follicles (6.4+/-0.7 vs 4.4+/-0.7; P = 0.04), embryos recovered (9.6+/-1.1 vs 4.9+/-1.1; P = 0.0025) and freezable embryos (4.7+/-0.7 vs 2.1+/-0.7; P = 0.014) than T1 heifers. It is concluded that a single daily subcutaneous injection of pFSH results in a lower superovulatory response than the twice daily regimen in heifers.

Journal Article↗
PubMed1993

Effects of continuous administration of gonadotropin-releasing hormone (GnRH) or a potent GnRH analogue on blood luteinizing hormone and testosterone concentrations in prepubertal bulls.

The objective was to determine if continuous administration of gonadotropin-releasing hormone (GnRH) or a potent analogue (GnRH-A) for 28 or 56 d would decrease blood concentrations of luteinizing hormone (LH) and testosterone (T) in 5-month old bull calves. Treatments (5 calves/treatment), using a completely randomized design, were: control (vehicle), 3.3, 10 and 30 micrograms GnRH, and 3.3 and 10 micrograms GnRH-A (Leuprolide) per kg bodyweight/d for 28 d, administered via subcutaneously implanted mini-osmotic pumps. A second pump was implanted on day 28 in controls and bulls receiving 10 micrograms GnRH-A until day 56. Blood samples were taken every second day for plasma LH and T concentrations, and every 15 min for 6 hr on days 1, 14 and 27 (and days 40 and 55 where applicable) for plasma LH concentrations. There was an increase (P < 0.05) in basal plasma LH in response to GnRH and GnRH-A on day 1 (1.6, 2.1, 2.1, 2.5, 2.1 and 1.9 ng/ml for control, 3.3, 10 and 30 micrograms GnRH, and 3.3 and 10 micrograms GnRH-A, respectively; pooled s.e.d. = 0.2), but not on days 14 or 27. The number of LH pulses/6 hr was similar on day 1 for GnRH-treated and control calves, but there was a linear decrease (P < 0.05) in pulse frequency in response to GnRH doses on days 14 (1.8, 1.2, 0.6 and 0.0 for control, 3.3, 10 and 30 micrograms GnRH; s.e.d. = 0.5) and 27 (1.8, 1.0, 0.0 and 0.0; s.e.d. = 0.3). On days 1, 14 and 27, both GnRH-A doses suppressed (P < 0.05) LH pulsatility. GnRH (days 1-14) and GnRH-A (days 1-27) increased (P < 0.05) plasma T in a dose-dependent manner. Mean T was greater (P < 0.05) in 10 micrograms GnRH-A-treated than in control calves during days 29-41 (4.6 and 1.8 ng/ml; s.e.d. = 0.6) and days 43-55 (4.1 and 1.8 ng/ml; s.e.d. = 0.4). In conclusion, continuous administration of GnRH or GnRH-A to 5-month old bulls for 28 or 56 d chronically decreased LH pulse frequency, had no effect on basal LH, but increased testosterone concentrations.

Analysis of Variance↗
PubMed1993

Effect of exogenous thyroxine on timing of seasonal reproductive transitions in ewes.

The thyroid gland is necessary for the transition from the breeding season to anestrus in the ewe, but the importance of seasonal changes in thyroxine in this process is not known. The objective of this experiment was to determine the effects of exogenous thyroxine during the breeding season on the time of the transition to anestrus and on the onset of the subsequent breeding season in ewes maintained on natural photoperiod. Cyclic Galway ewes were blocked on the basis of body weight and randomly allocated to the following groups: 1) untreated controls (n = 11), 2) placebo-injected controls (n = 9), and 3) ewes injected daily with thyroxine from the middle of the breeding season until the onset of anestrus (n = 10). Reproductive state was assessed from serum progesterone concentrations determined twice weekly until the breeding season had ended in placebo-injected controls, and until the onset of the subsequent breeding season in untreated and thyroxine-injected ewes. The mean (+/- SEM) date of onset of anestrus did not differ between untreated ewes (April 19 +/- 9 days) and placebo-injected controls (April 15 +/- 9 days; p > 0.05), but occurred earlier in ewes injected with thyroxine (February 28 +/- 6 days; p < 0.001). Thyroxine treatment during the breeding season, however, did not affect the onset of the subsequent breeding season. These data indicate that supplementary thyroxine during the breeding season can advance anestrus and thus shorten the duration of the breeding season.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗
PubMed1993

Active immunization of heifers against a synthetic fragment of bovine inhibin.

Two experiments were conducted in cyclic beef heifers to determine whether active immunization against bovine inhibin alpha 1-26 Gly-Tyr (bINH) affected follicular dynamics, hormone concentration or ovulation rate. In Expt 1, heifers (n = 9) were actively immunized against bINH conjugated to human alpha globulins (HAG) using bis-diazotized benzidine in non-ulcerative Freund's adjuvant (NUFA; primary on day 0; booster injections on days 53, 84 and 116 using conjugated bINH and on days 176 and 366 using unconjugated bINH; ten heifers were used as controls). Ovaries were examined daily using ultrasound scanning (days 70-155 and 384-391) and corresponding blood samples were collected for bINH antibody titre, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestradiol determinations. Four treated and four control heifers were injected with 10 micrograms gonadotrophin-releasing hormone (GnRH) on day 386 (day 2 of the oestrous cycle). Although bINH-immunized heifers had variable antibody titres ranging from 4 to 50% I125-labelled bINH bound to serum diluted 1:2000, ovulation rate was unaffected. In oestrous cycles with three dominant follicles, the ovulatory follicles grew faster (2.5 +/- 0.2 versus 1.6 +/- 0.3 mm day-1; mean +/- SEM), had shorter durations of growth (5.7 +/- 0.8 versus 9.6 +/- 1.6 days) and duration of detection (7.5 +/- 0.8 versus 12.0 +/- 2.4 days) in immunized heifers. Mean concentrations of FSH, LH and oestradiol were unaltered in most cases during oestrous cycles in bINH-immunized compared with control heifers. There was no significant difference in the percentage increase in FSH or LH, after GnRH injection, between control and immunized heifers. As ovulation rate was unaltered in the first experiment, a second similar study was designed using a different immunization protocol. In Expt 2, heifers were immunized with bINH conjugated to human serum albumin using glutaraldehyde with the following doses: 0.0 (control; n = 7), 0.33 (n = 7), 1.0 (n = 8) and 3.0 (n = 7) mg. Three booster immunizations were given 33, 66 and 209 days after primary immunization. Immunization increased the number of oestrous cycles with multiple ovulations (42 of 132 (32%) oestrous cycles examined) compared with controls (1 of 30 (3.3%) oestrous cycles examined). Neither titre nor ovulation rate was affected by dose of bINH used. In summary, following bINH immunization, ovulation rate was not increased despite changes in follicular dynamics in Expt 1, but was increased in 32% of oestrous cycles in Expt 2.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Induced ovulation of the first postpartum dominant follicle in beef suckler cows using a GnRH analogue.

There is a low incidence of ovulation of the first dominant follicle that develops in the early postpartum period of beef suckler cows, which prolongs the interval from calving to first ovulation. The objective of this study was to determine whether a single injection of a GnRH analogue would ovulate the first postpartum dominant follicle. Limousin x Friesian beef suckler cows were assigned at parturition, over two years (16 cows in year 1; 19 cows in year 2), to one of three treatments: (1) untreated (control; n = 12), (2) GnRH analogue (20 micrograms buserelin i.m.) administered in the growing-plateau phase of the first postpartum dominant follicle (GnRH-G; n = 12) and (3) GnRH analogue administered in the declining phase of the first postpartum dominant follicle (GnRH-D; n = 11). From day 8 or 9 post partum, the ovaries of each cow were examined daily by ultrasound to determine the time of GnRH injection and ovulation. Blood samples were collected daily for progesterone measurement to confirm ovulation and in year 2 to determine the duration of the first oestrous cycle. The mean (+/- SEM) number of days from parturition to development of the first dominant follicle was 11.0 +/- 0.3, 10.3 +/- 0.5 and 10.1 +/- 0.7 for cows assigned to treatments 1-3, respectively (P > 0.05). The proportion of cows ovulating the first dominant follicle was higher (P < 0.05) following GnRH treatment (12 of 12 and 7 of 10; GnRH-G and GnRH-D, respectively) than with controls (2 of 12).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Long-term effects of cimaterol in Friesian steers: I. Growth, feed efficiency, and selected carcass traits.

The objectives of this experiment were: 1) to determine whether feeding cimaterol to male calves from 4 wk of age until slaughter at target live weights of 275, 375, or 475 kg would result in a sustained increase in growth rate and feed conversion efficiency (FCE) and 2) to determine whether the effects of cimaterol on selected carcass traits would increase with increased duration of treatment. Ninety male Friesian calves 4 wk old were assigned at random to either a control or cimaterol group. Each animal was fed 1 kg of chopped barley straw and had ad libitum access to a pelleted diet containing either 0 or 4 ppm of cimaterol. Neither ADG nor FCE was affected by cimaterol during the first 5 wk of treatment. Growth rate of cimaterol-treated steers was 20% higher during wk 25 to 33. However, cimaterol had no overall effect on growth rate. Feed conversion efficiency was improved by 15 and 63% during wk 9 to 16 and wk 25 to 33, respectively. Cimaterol-treatment increased dressing percentage by an average of 3%, improved conformation score (2.2 vs 4.0, 3.0 vs 3.9, and 2.9 vs 3.2), and reduced subcutaneous fat score (1.7 vs 1.9, 1.3 vs 3.1, and 2.1 vs 3.4) for treated and control animals at target slaughter live weights of 275, 375, and 475 kg, respectively, but had no effect on carcass weight. On average, cimaterol treatment decreased carcass length by 2.5 cm, hide weight by 2.75 kg, and the weight of kidney and pelvic fat by 3.5 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Long-term effects of cimaterol in Friesian steers: II. Carcass composition and meat quality.

The objectives of this study were to examine the effects of long-term administration of cimaterol to steers from 4 wk of age until slaughter at target live weights of 275, 375, and 475 kg on 1) carcass composition; 2) distribution and growth of the dissectible lean, fat, and bone; and 3) selected meat quality traits. Ninety calves were allocated to either control or cimaterol (4 ppm) treatment with 15 from each treatment scheduled for slaughter at the above target live weights. Of the 90 calves, 73 carcasses were dissected. Cimaterol increased the proportion of lean in the carcass of the three target slaughter groups from 653, 629, and 612 g/kg in control steers to 728, 728, and 723 g/kg in treated steers, respectively, and decreased the proportion of fat from 134, 169, and 197 g/kg in control steers to 88, 86, and 99 g/kg in treated steers, respectively. Cimaterol increased the longissimus muscle area from 46.4, 56.7, and 62.4 cm2 in control steers to 61.0, 73.4, and 90.8 cm2 in treated steers in the three target slaughter groups, respectively. The allometric growth coefficients for total lean, bone, and fat were .987, .869, and 1.406, respectively, for treated animals and .898, .771, and 1.654, respectively, for control animals. Cimaterol increased the 2-d drip loss and the fiber-optic probe value of longissimus muscle. Shear force values were 55, 145, and 118% higher in the treated animals in the three target slaughter groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗