Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 29
Filter
Add more filters










Publication year range
1.
BMC Genomics ; 23(1): 74, 2022 Jan 23.
Article in English | MEDLINE | ID: mdl-35065600

ABSTRACT

BACKGROUND: Cattle production is dependent upon fertility because it results in producing offspring to offset production costs. A number of semen attributes are believed to affect fertility and are frequently measured as part of routine breeding soundness exams or semen collection procedures. The objective of this study was to perform a single-step genome-wide association study (ssGWAS) for beef bull semen attributes. Beef bull fertility phenotypes including volume (VOL), concentration (CONC), number of spermatozoa (NSP), initial motility (IMot), post-thaw motility (PTMot), three-hour post-thaw motility (3HRPTMot), percentage of normal spermatozoa (%NORM), primary abnormalities (PRIM), and secondary abnormalities (SEC) were obtained from two artificial insemination (AI) centers. A total of 1819 Angus bulls with 50,624 collection records were used for ssGWAS. A five-generation pedigree was obtained from the American Angus Association and consisted of 6521 sires and 17,136 dams. Genotypes on 1163 bulls were also obtained from the American Angus Association and utilized in ssGWAS. RESULTS: A multi-trait animal model was used for the estimation of single nucleotide polymorphism (SNP) effects. Significant SNP were those with a -log10 P-value threshold greater than 4.0. Volume, CONC, NSP, IMot, PTMot, 3HRPTMot, %NORM, PRIM, and SEC have five, three, six, seven, two, six, six, and two genome-wide significant SNP, respectively. CONCLUSIONS: Several significant SNP were determined to be near or within quantitative trait loci (QTL) associated with beef bull semen attributes. In addition, genes associated with fertility were found to contain or be near the significant SNP found in the study. The results indicate there are regions of the genome that impact fertility, proving inclusion of genomic information into genetic evaluation should be advantageous for genetic improvement of male fertility traits.


Subject(s)
Genome-Wide Association Study , Semen , Animals , Cattle , Fertility/genetics , Insemination, Artificial , Male , Semen Analysis , Sperm Motility/genetics , Spermatozoa
2.
Anim Reprod Sci ; 226: 106699, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33517066

ABSTRACT

This study was conducted to determine effects of pre-synchronization of ovulation timing among heifers and delayed fixed-time artificial insemination (TAI) with sex-sorted semen on proportion of heifers pregnant after TAI (PR/AI). Heifers were assigned to one of eight treatments: 1 and 2), 7-d CO-Synch + CIDR treatment regimen with administration of gonadotropin-releasing hormone and a CIDR insert on Day 0, prostaglandin F2α (PGF) at CIDR removal on Day 7, and TAI occurring 54 h later with conventionally processed (CTRL54-CNV) or sex-sorted semen (CTRL54-SEX); 3 and 4), same as CTRL54 but TAI delayed to 72 h with conventionally processed (CTRL72-CNV) or sex-sorted semen (CTRL72-SEX); 5 and 6), same as CTRL54 but additional administration of PGF on Day -7 and TAI with conventionally processed (PRE54-CNV) or sex-sorted semen (PRE54-SEX); 7 and 8), same as PRE54 treatments but TAI delayed to 72 h with conventionally processed (PRE72-CNV) or sex-sorted semen (PRE72-SEX). Proportion of heifers pregnant after TAI was greater (P ≤  0.02) with conventionally processed semen compared with sex-sorted semen, yet PR/AI did not differ (P =  0.14) between heifers in PRE72-CNV and PRE72-SEX groups. There were greater PR/AI in the PRE72-SEX (P =  0.03) than CTRL54-SEX group (46.1 % and 36.9 %) and there was no difference (P =  0.31) in PR/AI between CTRL54-CNV and PRE72-SEX groups (50.4 % and 46.1 %). In conclusion, pre-synchronization of ovulation timing among heifers combined with delayed TAI resulted in increased PR/AI with sex-sorted semen compared with the 7-d CO-Synch+CIDR treatment regimen.


Subject(s)
Cattle , Estrus Synchronization/methods , Insemination, Artificial/veterinary , Ovulation/physiology , Sex Preselection/veterinary , Animals , Dinoprost/administration & dosage , Dinoprost/analogs & derivatives , Dinoprost/pharmacology , Estradiol/pharmacology , Female , Gonadotropin-Releasing Hormone/pharmacology , Male , Pregnancy , Progesterone/pharmacology , Prostaglandins F/administration & dosage , Prostaglandins F/pharmacology
3.
J Anim Sci ; 95(8): 3631-3638, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28805910

ABSTRACT

The objective of these studies was to investigate the efficacy of an intravaginal triptorelin acetate (TA) gel as an ovulation-inducing agent in mares. In Exp. 1, 24 mares were blocked using a combination of parity and age and randomly assigned to 1 of 3 treatment groups: 5 mL TA gel (TA5), 10 mL TA gel (TA10), or 5 mL vehicle gel only (CON). Following the appearance of a follicle ≥ 25 mm, a blood sample was obtained for measurement of LH from each mare every 24 h until treatment administration. When a follicle ≥ 35 mm was observed, treatments were administered intravaginally. Following treatment, blood samples were collected for measurement of LH and ovaries were scanned via ultrasonography every 12 h until 48 h post-ovulation. Mares in both TA5 and TA10 tended ( = 0.08) to experience a brief surge in LH by 12 h post-treatment. There was a treatment by time interaction ( < 0.005). The interval from treatment to ovulation was not different between groups ( > 0.05). We hypothesized that duration of elevated LH was not sufficient to induce ovulation in most mares. In Exp. 2, 23 mares were blocked by parity/age and randomly assigned to 3 treatment groups: the CON ( = 7) and TA5 ( = 8) treatment groups remained the same, but the TA10 treatment was split into two 5-mL doses administered 24 h apart (TA5×2; = 8). Blood collection and ultrasonography occurred every 12 h on detection of a follicle ≥ 25 mm in diameter. Once a follicle ≥ 35 mm was detected, treatment was administered and ultrasonography and blood collection for measurement of LH occurred every 6 h until 48 h post-ovulation to get a more robust characterization of the effect of TA on LH and a more accurate timeframe in which ovulation was occurring. Mares in both TA5 and TA5×2 had an increase ( < 0.05) in LH by 6 h post-treatment, which was declining by 12 h post-treatment. Following the second dose in TA5×2, another rise in LH occurred, but to a lesser magnitude ( > 0.05) compared with the initial dose. Again there was a treatment by time interaction ( < 0.005) and in Exp. 2 the interval from treatment to ovulation was shorter in TA5 (61.5 ± 8.8 h) and TA5×2 (61.5 ± 9.6 h) compared with CON (123.1 ± 21.7 h; < 0.01). In Exp. 2, administration of TA gel increased LH concentrations and hastened the interval from treatment to ovulation in mares, without an advantage in the timing of ovulation noted between the 5 or 10-mL doses, or administration of two 5-mL doses given 24 h apart.


Subject(s)
Horses/physiology , Luteinizing Hormone/administration & dosage , Ovulation Induction/veterinary , Reproduction , Triptorelin Pamoate/administration & dosage , Acetates/administration & dosage , Administration, Intravaginal , Animals , Female , Ovarian Follicle/drug effects , Ovary/drug effects , Ovulation/drug effects , Pregnancy
4.
J Anim Sci ; 95(3): 1219-1231, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28380530

ABSTRACT

The objective of this study was to examine the effects of growth-promoting technologies (GP) and postmortem aging on longissimus lumborum muscle fiber cross-sectional area (CSA), collagen solubility, and their relationship to meat tenderness. Two groups of black-hided crossbred feedlot heifers (group 1: = 33, initial BW 430 ± 7 kg; group 2: = 32, initial BW 466 ± 7 kg) were blocked by BW and assigned to 1 of 3 treatments consisting of: no implant and no ractopamine hydrochloride (CON; = 21); implant, no ractopamine hydrochloride (IMP; = 22); implant and ractopamine hydrochloride (COMBO; = 22). Heifers that received an implant were administered an implant containing 200 mg trenbolone acetate and 20 mg estradiol on d 0 of the study, and heifers in the COMBO group received 400 mg∙head∙d of ractopamine hydrochloride for 28 (Group 1) or 29 d (Group 2) at the end of 90- (Group 1) or 106-d (Group 2) feeding period. Following harvest, strip loins were collected and further fabricated into 5 roasts for postmortem aging (DOA) periods of 2, 7, 14, 21, or 35 d. After aging, Warner-Bratzler shear force (WBSF), muscle fiber CSA, and collagen solubility were measured. There was no treatment × DOA interaction for WBSF ( = 0.86), but treatment and DOA impacted WBSF ( < 0.01). Over the entire aging study, COMBO steaks had greater ( < 0.01) shear force values when compared to CON steaks. The IMP steaks tended to have decreased ( = 0.07) shear force when compared to the COMBO steaks, but did not differ ( = 0.11) from CON steaks. The IMP and COMBO treatments had increased type IIA fiber CSA when compared to CON ( < 0.01). When compared to each other, the IMP and COMBO type IIA fiber CSA did not differ ( = 0.76). Type I and IIX fiber CSA tended to be greater than CON for IMP and COMBO treatments ( < 0.10). There was no treatment × DOA interaction for all collagen measures ( > 0.33). Collagen amounts were not impacted by GP treatment ( > 0.72), but DOA increased the concentration of soluble collagen ( = 0.04). Fiber CSA of all fiber types were positively correlated ( < 0.05; = 0.21 to 0.28) with WBSF only on d 2 of aging, while soluble collagen amount tended to negatively correlate with WBSF on d 7 and 14 of aging ( < 0.10; = -0.24 and -0.23, respectively). Administration of GP during heifer finishing resulted in greater steak WBSF over 35 d of aging, which was not due to collagen characteristics and only minimally affected by fiber CSA.


Subject(s)
Adrenergic beta-Agonists/pharmacology , Cattle/physiology , Collagen/chemistry , Muscle Fibers, Skeletal/drug effects , Phenethylamines/pharmacology , Red Meat/analysis , Aging , Animals , Female , Solubility
5.
J Anim Sci ; 95(11): 5105-5111, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29293737

ABSTRACT

Our objective was to determine which of 2 split-time AI programs applied to suckled beef cows would result in greater pregnancy risk. Suckled beef cows (n = 1,062) at 12 locations in 4 states (CO, KS, MY, and WA) were enrolled. Cows were treated on d -7 with a progesterone insert concurrent with 100 µg GnRH and on d 0 with 25 mg PGF plus removal of the insert. Estrus-detection patches were affixed to cows at insert removal. The study was designed as a completely randomized experiment of 2 treatment combinations. Within location and balanced for parity (primiparous vs. multiparous), cows were assigned randomly to 2 treatment times (55 vs. 65 h after CIDR insert removal) at which time estrus-detection patches were assessed. Estrus was defined to have occurred when an estrus-detection patch was > 50% colored (activated). Cows determined to be in estrus were inseminated at either 55 or 65 h, whereas the residual nonestrous cows in both treatment times received GnRH at 55 or 65 h but were inseminated 20 h later at 75 or 85 h, respectively. Pregnancy outcomes were determined at 36 d after AI and at the end of the breeding season. Thus, pregnancy outcomes of interest were compared between the 55 + 75-h treatment combination and that of the 65+85-h combination. Expression of estrus was greater ( = 0.001) by 65 h after PGF than by 55 h (62.0% vs. 41.9%), respectively, and this proportion was influenced by parity (time x parity interaction; = 0.006). As a result, proportionally more ( < 0.001) cows received the timed AI at 75 than 85 h (59.4% vs. 40.6%). Similar proportions of cows not in estrus by 55 or 65 h were detected in estrus by 75 or 85 h (40.1% vs. 39.3%), respectively. The cumulative proportion of cows in estrus by 75 h was less ( < 0.001) than that by 85 h (66.7% vs. 76.7%), respectively. Pregnancy risks at 36 d differed among treatments, with cows detected in estrus and inseminated at 55 or 65 h having greater pregnancy risks than their time-inseminated herd mates at 75 or 85 h (62.3% vs.49.7%), respectively. Overall pregnancy risk for cows in the 65+85-h treatment combination was greater at 36 d than for cows in the 55 + 75-h treatment combination (61.0% vs. 51.4%), respectively. We conclude that the 65 + 85-h treatment combination produced more pregnancies than the 55 + 75-h combination, but its implementation may be somewhat less convenient in terms of cow handling times.


Subject(s)
Cattle/physiology , Gonadotropin-Releasing Hormone/administration & dosage , Insemination, Artificial/veterinary , Pregnancy Outcome/veterinary , Progesterone/administration & dosage , Animals , Estrus , Estrus Detection , Female , Parity , Pregnancy , Risk , Time Factors
6.
J Anim Sci ; 94(9): 3722-3728, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27898908

ABSTRACT

We hypothesized that GnRH would increase pregnancy risk (PR) in a split-time AI program for cows in which estrus was not detected. A total of 1,236 suckled beef cows at 12 locations in 3 states (Colorado, Kansas, and North Dakota) were enrolled. Before applying the fixed-time AI program, BCS was assessed. Cows were treated on d -7 with a progesterone insert concurrent with 100 µg GnRH and on d 0 with 25 mg PGF plus removal of the insert. Estrus-detection patches were affixed to cows at insert removal. Estrus was defined to have occurred when an estrus-detection patch was >50% colored (activated). Cows in estrus by 65 h ( = 758; 61.3% of all cows) were randomly allocated to 2 treatments: 1) 100 µg GnRH and early + GnRH (E+G; = 373) or 2) AI only at 65 h (early - no GnRH [E-G]; = 385). The remaining cows were randomly allocated to 2 treatments: 1) 5(L+G; = 252) or 2) AI only at 84 h (late no GnRH [L-G]; = 226). Pregnancy was determined 35 d after AI via transrectal ultrasound. Pregnancy risk did not differ ( = 0.68) between E+G and E-G cows (61.9 vs. 60.4%, respectively). Conversely, for cows inseminated at 84 h, PR was greater ( = 0.01) in cows that received GnRH (L+G) compared with their herd mates not receiving GnRH (L- G; 41.7 vs. 30.8%, respectively). Of those cows not detected in estrus by 65 h, 42.1% were detected by 84 h, for a total expression of estrus by all cows of 77.6%. Administration of GnRH increased ( < 0.01) PR in cows not detected in estrus by 84 h (+GnRH = 33.4% [ = 146] vs. no GnRH = 15.0% [ = 128]) but had no effect in cows expressing estrus by 84 h (+GnRH = 65.3% [ = 103] vs. no GnRH = 61.7% [ = 97]). Neither estrus expression by 65 or 84 h nor PR was influenced by BCS, parity, or days postpartum at AI. Cows had greater PR when they had been detected in estrus before AI, and PR was improved by administration of GnRH at 65 h after insert removal in cows that were not detected in estrus and inseminated at 84 h.


Subject(s)
Cattle/physiology , Gonadotropin-Releasing Hormone/administration & dosage , Animals , Colorado , Estrus , Estrus Detection , Estrus Synchronization , Female , Insemination, Artificial/veterinary , Kansas , North Dakota , Parity , Postpartum Period , Pregnancy , Pregnancy Rate , Progesterone/administration & dosage , Random Allocation , Risk
7.
J Anim Sci ; 94(9): 3703-3710, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27898921

ABSTRACT

A multilocation study examined pregnancy risk (PR) after delaying AI in suckled beef cows from 60 to 75 h when estrus had not been detected by 60 h in response to a 7-d CO-Synch + progesterone insert (CIDR) timed AI (TAI) program (d -7: CIDR insert concurrent with an injection of GnRH; d 0: PGF injection and removal of CIDR insert; and GnRH injection at TAI [60 or 75 h after CIDR removal]). A total of 1,611 suckled beef cows at 15 locations in 9 states (CO, IL, KS, MN, MS, MT, ND, SD, and VA) were enrolled. Before applying the fixed-time AI program, BCS was assessed, and blood samples were collected. Estrus was defined to have occurred when an estrus detection patch was >50% colored (activated). Pregnancy was determined 35 d after AI via transrectal ultrasound. Cows ( = 746) detected in estrus by 60 h (46.3%) after CIDR removal were inseminated and treated with GnRH at AI (Control). Remaining nonestrous cows were allocated within location to 3 treatments on the basis of parity and days postpartum: 1) GnRH injection and AI at 60 h (early-early = EE; = 292), 2) GnRH injection at 60 h and AI at 75 h (early-delayed = ED; = 282), or 3) GnRH injection and AI at 75 h (delayed-delayed = DD; = 291). Control cows had a greater ( < 0.01) PR (64.2%) than other treatments (EE = 41.7%, ED = 52.8%, DD = 50.0%). Use of estrus detection patches to delay AI in cows not in estrus by 60 h after CIDR insert removal (ED and DD treatments) increased ( < 0.05) PR to TAI when compared with cows in the EE treatment. More ( < 0.001) cows that showed estrus by 60 h conceived to AI at 60 h than those not showing estrus (64.2% vs. 48.1%). Approximately half (49.2%) of the cows not in estrus by 60 h had activated patches by 75 h, resulting in a greater ( < 0.05) PR than their nonestrous herd mates in the EE (46.1% vs. 34.5%), ED (64.2% vs. 39.2%), and DD (64.8% vs. 31.5%) treatments, respectively. Overall, cows showing estrus by 75 h (72.7%) had greater ( < 0.001) PR to AI (61.3% vs. 37.9%) than cows not showing estrus. Use of estrus detection patches to allow for a delayed AI in cows not in estrus by 60 h after removal of the CIDR insert improved PR to TAI by optimizing the timing of the AI in those cows.


Subject(s)
Cattle/physiology , Estrus Detection/instrumentation , Estrus/physiology , Insemination, Artificial/veterinary , Animals , Dinoprost/administration & dosage , Estrus Synchronization/methods , Female , Gonadotropin-Releasing Hormone/administration & dosage , Lactation , Pregnancy , Pregnancy Rate , Progesterone/blood , United States
8.
J Anim Sci ; 94(2): 483-9, 2016 Feb.
Article in English | MEDLINE | ID: mdl-27065118

ABSTRACT

The objective of this study was to elucidate the phenotypic relationships between docility and first-service AI conception rate in heifers. Data ( = 337) collected from 3 cooperator herds in Kansas at the start of synchronization protocol included exit velocity (EV), chute score (CS), fecal cortisol (FC), and blood serum cortisol (BC). Data were analyzed using logistic regression with 30-d pregnancy rate as the dependent variable. The model included the fixed effect of contemporary group and the covariates FC, BC, EV, CS, BW, and age. Correlation coefficients were calculated between all continuous traits. Pregnancy rate ranged from 34% to 60% between herds. Blood cortisol positively correlated with EV ( = 0.22, < 0.01), negatively correlated with age ( = -0.12, < 0.03), and tended to be negatively correlated with BW ( = -0.10, = 0.09). Exit velocity was positively correlated with CS ( = 0.24, < 0.01) and negatively correlated with BW ( = -0.15, < 0.01) and age ( = -0.12, < 0.03). Chute score negatively correlated with age ( = -0.14, < 0.01), and age and BW were moderately positively correlated ( = 0.42, < 0.01), as expected. Older, heavier animals generally had better temperament, as indicated by lower BC, EV, and CS. The power of our test could detect no significant predictors of 30-d pregnancy for the combined data from all ranches. When the data were divided by ranch, CS ( < 0.03) and BW ( < 0.01) were both significant predictors for 30-d pregnancy for ranch 1. The odds ratio estimate for CS has an inverse relationship with pregnancy, meaning that a 1-unit increase in average CS will reduce the probability of pregnancy at ranch 1 by 48.1%. Weight also has a negative impact on pregnancy because a 1-kg increase in BW will decrease the probability of pregnancy by 2.2%. Fertility is a complex trait that depends on many factors; our data suggest that docility is 1 factor that warrants further investigation.


Subject(s)
Cattle/psychology , Reproduction/physiology , Temperament , Animals , Behavior, Animal , Body Weight , Cattle/physiology , Female , Hydrocortisone/blood , Insemination, Artificial/veterinary , Pregnancy , Pregnancy Rate
9.
J Anim Sci ; 94(2): 869-81, 2016 Feb.
Article in English | MEDLINE | ID: mdl-27065157

ABSTRACT

The objective of the study was to examine the effect of growth-promoting technologies (GP) on Longissimus lumborum steak tenderness, muscle fiber cross-sectional area (CSA), and collagen solubility. Crossbred feedlot heifers ( = 33; initial BW 464 ± 6 kg) were blocked by BW and assigned to 1 of 3 treatments: no GP (CON; = 11); implant, no zilpaterol hydrochloride (IMP; = 11); implant and zilpaterol hydrochloride (COMBO; = 11). Heifers assigned to receive an implant were administered Component TE-200 on d 0 of the study, and the COMBO group received 8.3 mg/kg DM of zilpaterol hydrochloride for the final 21 d of feeding with a 3 d withdrawal period. Following harvest, strip loins were collected and fabricated into 4 roasts and aged for 3, 14, 21, or 35 d postmortem. Fiber type was determined by immunohistochemistry. After aging, objective tenderness and collagen solubility were measured. There was a treatment × day of aging (DOA) interaction for Warner-Bratzler shear force (WBSF; < 0.01). At d 3 of aging, IMP and COMBO steaks had greater WBSF than CON steaks ( < 0.01). By d 14 of aging, the WBSF of IMP steaks was not different ( = 0.21) than CON steaks, but COMBO steaks had greater shear values than steaks of other treatments ( < 0.02). The COMBO steaks only remained tougher ( = 0.04) than the CON steaks following 35 DOA. Compared to CON muscles, IMP and COMBO type I and IIX muscle fibers were larger ( < 0.03). Treatment, DOA, or the two-way interactions did not impact measures of total and insoluble collagen ( > 0.31). Soluble collagen amount tended to be affected ( 0.06) by a treatment × DOA interaction which was due to COMBO muscle having more soluble collagen than the other 2 treatments on d 21 of aging ( < 0.02). Correlation analysis indicated that type I, IIA, and IIX fiber CSA are positively correlated with WBSF at d 3 and 14 of aging ( < 0.01), but only type IIX fibers are correlated at d 21 and 35 of aging ( < 0.03). At these time periods, total and insoluble collagen became positively correlated with WBSF ( < 0.01). This would indicate that relationship between muscle fiber CSA and WBSF decreases during postmortem aging, while the association between WBSF and collagen characteristics strengthens. The use of GP negatively impacted meat tenderness primarily through increased muscle fiber CSA and not through altering collagen solubility.


Subject(s)
Collagen/physiology , Cooking , Meat/analysis , Muscle Fibers, Skeletal/drug effects , Trimethylsilyl Compounds/pharmacology , Adrenergic beta-Agonists/administration & dosage , Adrenergic beta-Agonists/pharmacology , Aging , Animals , Cattle , Collagen/chemistry , Drug Implants , Female , Sensation , Trimethylsilyl Compounds/administration & dosage
10.
J Anim Sci ; 91(2): 666-72, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23230105

ABSTRACT

Two experiments were conducted over 3 yr to determine pregnancy rates in beef heifers after a timed AI in response to the 7-11 Synch protocol. In Exp. 1, 179 heifers were either fed melengestrol acetate (MGA; 7-11 Synch) or given an intravaginal progesterone (P4)-releasing insert [controlled intravaginal drug releasing device (CIDR); 7-11 CIDR] for 7 d. Prostaglandin F2αwas administered on the last day of MGA feeding or at CIDR removal followed by the CO-Synch protocol (GnRH-PGF2α-GnRH) beginning 4 d after MGA withdrawal or 2 d after CIDR removal. Heifers received a timed AI with GnRH beginning 48 h after the second PGF2α. Blood samples were collected at d -10, 0 (start of MGA feeding), and 18 (second PGF2α injection). In Exp. 2, 298 beef heifers were treated with the 7-11 Synch protocol with (7-11 Synch) or without (7 Synch) the first GnRH injection. Fixed time AI and GnRH was given 54 h after PGF2α. Blood samples were collected at d -10 and 0 in yr 1 and d -10, 0, 18 and at AI in yr 2. In Exp. 1, no differences were detected between 7 and 11 Synch and 7-11 CIDR for attainment of puberty in noncyclic heifers (94 vs. 78%; P = 0.21), the proportion of heifers that had luteal tissue on d 18 (87 vs. 83%; P = 0.41), or pregnancy rates after timed AI (47 vs. 46%; P = 0.99). In Exp. 2, administration of GnRH 4 d after the last MGA (7-11 Synch) feeding tended (P = 0.07) to induce more prepubertal heifers to cycle (88 vs. 61%) and increased (P < 0.01) the proportion of heifers with luteal tissue on d 18 (88 vs. 72%) compared with heifers in the 7 Synch treatment. Pregnancy rates after the 54 h timed AI were greater (P < 0.01) in the 7-11 Synch treatment (55%) than in the 7 Synch (38%). We conclude that heifer pregnancy rates did not differ whether feeding MGA for 7 d or applying a CIDR insert for 7 d before a CO-Synch protocol. In contrast, use of GnRH at the beginning of the CO-Synch protocol improved pregnancy rates after a timed AI by inducing more prepubertal heifers to ovulate and increasing the proportion of heifers with luteal tissue at the PGF2α injection.


Subject(s)
Cattle/physiology , Estrus Synchronization/methods , Melengestrol Acetate/pharmacology , Progesterone/pharmacology , Animals , Female , Fertility , Insemination, Artificial/veterinary , Melengestrol Acetate/administration & dosage , Pregnancy , Progesterone/administration & dosage , Progesterone/blood
12.
J Anim Sci ; 81(3): 571-86, 2003 Mar.
Article in English | MEDLINE | ID: mdl-12661636

ABSTRACT

In Exp. 1, 187 lactating beef cows were treated with injections of GnRH 7 d before and 48 h after prostaglandin F2alpha (PGF2alpha; Cosynch) or with Cosynch plus a 7-d treatment with an intravaginal progesterone (P4)-releasing insert (CIDR-B; Cosynch + CIDR). In Exp. 2, 183 lactating beef cows were treated with the Cosynch protocol or with Cosynch plus a 7-d treatment with norgestomet (Cosynch + NORG). In Exp. 1 and 2, blood samples for later P4 analyses were collected on d -17, -7 (first GnRH injection), 0 (PGF2alpha injection), and at timed artificial insemination (TAI; 48 h after PGF2alpha). In Exp. 3, 609 lactating beef cows were treated with the Cosynch + CIDR protocol or were fed 0.5 mg of melengestrol acetate (MGA) per day for 14 d before initiating the Cosynch protocol 12 d after the 14th d of MGA feeding (MGA + Cosynch). Blood samples were collected as in Exp. 1 and 2, plus additional samples on d -33 and -19 before PGF2alpha. In Exp. 4, 360 lactating beef cows were treated with a Cosynch + CIDR protocol, with TAI occurring at either 48 or 60 h after PGF2alpha, while receiving either GnRH or saline to form four treatments. Blood samples were collected as in Exp. 1 and 2. In Exp. 1, addition of P4 reduced the ability of the first GnRH injection to induce ovulation in anestrous cows with low P4 before PGF2alpha but improved (P = 0.06) pregnancy rates (61 vs 66%). In Exp. 2, the addition of NORG mimicked P4 by likewise increasing (P < 0.01) pregnancy rates (31 vs 51%) beyond those after Cosynch. In Exp. 3, the Cosynch + CIDR protocol increased (P < 0.001) pregnancy rates from 46 to 55% compared to the MGA + Cosynch protocol. In Exp. 4, administration of GnRH at TAI improved (P < 0.05) pregnancy outcomes (50 vs 42%), whereas timing of TAI had limited effects. We conclude that a progestin treatment concurrent with the Cosynch protocol improved pregnancy outcomes in all experiments, but pretreatment of cows with MGA was not as effective as the CIDR insert or NORG implants in this Cosynch-TAI model. Most of the improvement in pregnancy rates was associated with the increase in pregnancy rates of anestrous cows, regardless of whether ovulation was successfully induced in response to GnRH 7 d before PGF2alpha. Injection of GnRH at TAI following the Cosynch + CIDR protocol increased pregnancy rates in cycling cows with high P4 before the PGF2alpha injection and in anestrous cows with low P4 before PGF2alpha injection.


Subject(s)
Cattle/physiology , Melengestrol Acetate/pharmacology , Pregnancy, Animal/physiology , Pregnenediones/pharmacology , Progesterone Congeners/pharmacology , Progesterone/pharmacology , Administration, Intravaginal , Animal Husbandry/methods , Animals , Cattle/blood , Dinoprost/blood , Dinoprost/pharmacology , Estrus Synchronization/drug effects , Female , Gonadotropin-Releasing Hormone/blood , Gonadotropin-Releasing Hormone/pharmacology , Insemination, Artificial/veterinary , Lactation/physiology , Luteinizing Hormone/blood , Melengestrol Acetate/administration & dosage , Ovulation Induction/veterinary , Pregnancy , Pregnancy Rate , Pregnancy, Animal/drug effects , Pregnenediones/administration & dosage , Progesterone/administration & dosage , Progesterone Congeners/administration & dosage , Random Allocation , Time Factors
13.
J Anim Sci ; 80(10): 2688-94, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12413092

ABSTRACT

Secretion into the uterine lumen follows a precise pattern during early pregnancy. Near the end of the second week of pregnancy and coincident with elongation of conceptuses, retinol, retinol binding protein (RBP), estradiol (E2), and prostaglandins E (PGE) and F (PGF) increase in the uterine lumen, and RBP mRNA increases in the endometrium. In the present studies the potential for E2 (0.1 microM) and retinol (10 microM) to regulate RBP and PG production by cultured luminal (LEC) and glandular (GEC) epithelial cells collected from postpubertal females and LEC from prepubertal gilts was examined. Endometrial tissue was collected surgically from cyclic and pregnant females (n = 8) on d 10 and 13 postestrus (first day of estrus = d 0) and from 120- and 150-d-old prepubertal gilts that were treated with progesterone (P4) (2.2 mg x kg(-1) x d(-1), n = 6) or corn oil (n = 6) for 14 d prior to tissue collection. The LEC from postpubertal females responded to retinol with increased (P < 0.05) RBP, PGE, and PGF in culture medium and increased (P < 0.07) RBP mRNA but E2 decreased (P < 0.05) RBP and RBP mRNA and had no effect on prostaglandins. No E2 or retinol effects on secretions of GEC occurred in vitro, but a day x pregnancy status interaction (P < 0.06) affected PGE output by the GEC. Secretion of PGE was greater when GEC were collected on d 10 of pregnancy than from d-10 cyclic or d-13 pregnant or cyclic females. Both E2 and retinol stimulated (P < 0.05) secretion of RBP by LEC isolated from prepubertal gilts, but their effects were not additive. In vivo treatment of prepubertal gilts with P4 increased (P < 0.05) RBP and decreased (P < 0.05) PG production by LEC in vitro. Therefore responses to E2 and retinol differ between pre- and post-pubertal females, and retinol may function in the regulation of endometrial RBP and PG secretion.


Subject(s)
Endometrium/metabolism , Estradiol/pharmacology , Prostaglandins/metabolism , Retinol-Binding Proteins/metabolism , Swine/physiology , Vitamin A/pharmacology , Animals , Endometrium/cytology , Endometrium/drug effects , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Estradiol/physiology , Female , In Vitro Techniques , Pregnancy , Progesterone/blood , Progesterone/physiology , Prostaglandins E/metabolism , Prostaglandins F/metabolism , RNA, Messenger/metabolism , Retinol-Binding Proteins/genetics , Time Factors , Uterus , Vitamin A/physiology
14.
Vet Immunol Immunopathol ; 87(1-2): 79-87, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12052345

ABSTRACT

Glucocorticoids are reported to bias cytokines to a Th2 phenotype. However, this dogma has been advanced largely from studies utilizing potent glucocorticoid analogs. The current study was conducted to revisit the issue of glucocorticoid modulation of Th1/Th2 cytokine production and evaluate migration inhibitory factor (MIF) mRNA expression in cultured pig splenocytes treated with physiologically relevant concentrations of cortisol (CORT). Dexamethasone (DEX) was included for comparison. In Experiment 1, DEX, at 150 and 300 nM, suppressed concanavalin (ConA)-stimulated IFNgamma at both 12 and 24 h in culture, and IL-10 at 24h (P<0.05). Both 150 and 300 nM CORT suppressed IL-10 at 24 h (P<0.05), but neither concentration affected IFNgamma at 24 h. In Experiment 2, cells were cultured with a broader range of CORT for 48 h following ConA. Parallel cultures with identical treatments also were conducted in separate plates for evaluation of glucocorticoid regulation of MIF mRNA. IFNgamma was reduced by 300 nM DEX at 12, 24, and 48 h (P<0.05), whereas 150 and 300 nM CORT blunted IFNgamma at 24 h (P<0.05), but not 48 h. ConA increased IL-2 (P<0.01), but none of the steroid treatments affected IL-2. At both 12 and 24 h, IL-10 was reduced by 300 nM DEX and by 150 and 300 nM CORT (P<0.05). ConA increased relative abundance of MIF mRNA (P<0.001), but no steroid treatment affected MIF mRNA. In Experiment 3, steroid additions were delayed by 24 h after ConA, and cytokine concentrations evaluated 48 h later. Again, separate cultures were used for determination of effect of treatments on MIF mRNA. None of the steroid treatments affected IFNgamma, but 300 nM DEX reduced IL-10 (P<0.05). All of the CORT treatments (75-300 nM) reduced MIF mRNA (P<0.05), whereas DEX did not affect MIF mRNA in this experiment. The current experiments suggest that both DEX and high physiological concentrations of CORT can suppress both type 1 and type 2-like cytokines in cultured pig splenocytes. But, IL-10 was generally more sensitive to CORT suppression with increased time in culture than was IFNgamma. In addition, MIF mRNA could be suppressed by delayed addition of CORT to porcine splenocytes. Taken together, the data do not support the hypothesis that CORT directs the cytokine milieu toward a type 2 bias in cultured pig splenocytes.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Hydrocortisone/pharmacology , Interferon-gamma/biosynthesis , Interleukin-10/biosynthesis , Interleukin-2/biosynthesis , Swine/immunology , Animals , Blotting, Northern/veterinary , Cells, Cultured , Dexamethasone/pharmacology , Female , Glucocorticoids/pharmacology , Interferon-gamma/immunology , Interleukin-10/immunology , Interleukin-2/immunology , Macrophage Migration-Inhibitory Factors/biosynthesis , Macrophage Migration-Inhibitory Factors/genetics , Macrophage Migration-Inhibitory Factors/immunology , Male , RNA, Messenger/metabolism , Th1 Cells/drug effects , Th1 Cells/immunology , Th1 Cells/metabolism , Th2 Cells/drug effects , Th2 Cells/immunology , Th2 Cells/metabolism
15.
J Anim Sci ; 80(6): 1652-62, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12078747

ABSTRACT

Four experiments were conducted to evaluate the influence of changing the proportion of supplemental degradable intake protein (DIP) from urea on forage intake, digestion, and performance by beef cattle consuming either low-quality, tallgrass prairie forage (Exp. 1, 2, and 4) or forage sorghum hay (Exp. 3). Experiments 1, 2, and 3 were intended to have four levels of supplemental DIP from urea: 0, 20, 40, and 60%. However, refusal to consume the 60% supplement by cows grazing tallgrass prairie resulted in elimination of this treatment from Exp. 1 and 2. Levels of supplemental DIP from urea in Exp. 4 were 0, 15, 30, and 45%. Supplements contained approximately 30% CP, provided sufficient DIP to maximize digestible OM intake (DOMI) of low-quality forage diets, and were fed to cows during the prepartum period. In Exp. 1, 12 Angus x Hereford steers (average initial BW = 379) were assigned to the 0, 20, and 40% treatments. Forage OM intake, DOMI, OM, and NDF digestion were not affected by urea level. In Exp. 2, 90 pregnant, Angus x Hereford cows (average initial BW = 504 kg and body condition [BC] = 5.0) were assigned to the 0, 20, and 40% treatments. Treatment had little effect on cow BW and BC changes and calf birth weight, ADG, or weaning weight. However, pregnancy rate tended to be lowest (P = 0.13) for the greatest level of urea. In Exp. 3, 120 pregnant, crossbred beef cows (average initial BW = 498 kg and BC = 4.6) were assigned to the 0, 20, 40, and 60% treatments. Prepartum BC change tended (P = 0.08) to be quadratic (least increase for 60% treatment), although BW change was not statistically significant. Treatment effect on calf birth weight was inconsistent (cubic; P = 0.03), but calf ADG and weaning weight were not affected by treatment. Pregnancy rate was not affected by prepartum treatment. In Exp. 4, 132 pregnant, Angus x Hereford cows (average initial BW = 533 and BC = 5.3) were assigned to the 0, 15, 30, and 45% treatments. Prepartum BC loss was greatest (quadratic; P = 0.04) for the high-urea (45%) treatment, although BW loss during this period declined linearly (P < 0.01). Prepartum treatment did not affect pregnancy rate, calf birth weight, or ADG. In conclusion, when sufficient DIP was offered to prepartum cows to maximize low-quality forage DOMI, urea could replace between 20 and 40% of the DIP in a high-protein (30%) supplement without significantly altering supplement palatability or cow and calf performance.


Subject(s)
Animal Feed/analysis , Cattle/physiology , Dietary Proteins/metabolism , Nitrogen/pharmacology , Pregnancy, Animal/physiology , Animal Nutritional Physiological Phenomena , Animals , Body Weight , Cattle/growth & development , Cattle/metabolism , Dietary Supplements , Digestion , Female , Male , Poaceae , Pregnancy , Pregnancy Rate , Urea/chemistry
16.
J Anim Sci ; 78(7): 1747-58, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10907816

ABSTRACT

Three experiments were conducted to induce estrus and(or) ovulation in 1,590 suckled beef cows at the beginning of a spring breeding season. In Exp. 1, 890 cows at three locations were allotted to three treatments: 1) GnRH on d -7 + prostaglandin F2alpha (PGF2alpha) on d 0 (Select Synch); 2) GnRH on d -7 + PGF2alpha on d 0 (first day of the breeding season) plus a norgestomet implant (NORG) between d -7 and 0 (Select Synch + NORG); or 3) two injections of PGF2alpha given 14 d apart (2xPGF2alpha). More (P < 0.05) cycling cows were detected to have been in estrus after both treatments that included GnRH, whereas, among noncycling cows, the addition of norgestomet further increased (P < 0.05) the proportion in estrus. Pregnancy rates were greater (P < 0.01) among noncycling cows after treatments that included GnRH. For cows that calved >60 d before the onset of the breeding season, conception rates were greater (P < 0.01) than those that calved < or =60 d regardless of treatment, whereas days postpartum had no effect on rates of detected estrus. When body condition scores were < or =4 compared with >4, rates of detected estrus (P < 0.05) and conception (P = 0.07) were increased. In Exp. 2, 164 cows were treated with the Select Synch + NORG treatment and were inseminated either after estrus or at 16 h after a second GnRH injection (given 48 h after PGF2alpha). Conception and pregnancy rates tended (P = 0.08) to be or were less (P < 0.05), respectively, for noncycling cows inseminated by appointment, but pregnancy rates exceeded 53% in both protocols. In Exp. 3, 536 cows at three locations were treated with the Select Synch protocol as in Exp. 1 and inseminated either: 1) after detected estrus (Select Synch); 2) at 54 h after PGF2alpha when a second GnRH injection also was administered (Cosynch); or 3) after detected estrus until 54 h, or in the absence of estrus, at 54 h plus a second GnRH injection (Select Synch + Cosynch). Conception rates were reduced (P < 0.01) in cows that were inseminated by appointment. An interaction of AI protocol and cycling status occurred (P = 0.05) for pregnancy rates with differing results for cycling and noncycling cows. Across experiments, variable proportions of cows at various locations (21 to 78%) were cycling before the breeding season. With the GnRH or GnRH + NORG treatments, ovulation was induced in some noncycling cows. Conception rates were normal and pregnancy rates were greater than those after a PGF2alpha program, particularly when inseminations occurred after detected estrus.


Subject(s)
Cattle/physiology , Dinoprost/pharmacology , Estrus Synchronization , Gonadotropin-Releasing Hormone/pharmacology , Insemination, Artificial/veterinary , Ovulation/drug effects , Pregnenediones/pharmacology , Progesterone Congeners/pharmacology , Animal Husbandry/methods , Animals , Dinoprost/administration & dosage , Drug Combinations , Female , Gonadotropin-Releasing Hormone/administration & dosage , Male , Ovulation Induction/veterinary , Pregnancy , Pregnenediones/administration & dosage , Progesterone Congeners/administration & dosage , Time Factors
17.
J Anim Sci ; 77(7): 1823-32, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10438030

ABSTRACT

Cycling (n = 16) and noncycling (n = 24), early postpartum, suckled beef cows of three breeds were assigned randomly to three treatments: 1) 100-microg injection of GnRH plus a 6-mg implant of norgestomet administered on d -7 before 25 mg of PGF2alpha and implant removal on d 0 (GnRH+NORG); 2) 100 microg of GnRH given on d -7 followed by 25 mg of PGF2alpha on d 0 (GnRH); or 3) 2 mL of saline plus a 6-mg implant of norgestomet administered on d -7 followed by 25 mg of PGF2, and implant removal on d 0 (NORG). All cows were given 100 microg of GnRH on d +2 (48 h after PGF2alpha). Blood sera collected daily from d -7 to d +4 were analyzed for progesterone and estradiol-17beta, and ovaries were monitored daily by transrectal ultrasonography to assess changes in ovarian structures. Luteal structures were induced in 75% of noncycling cows in both treatments after GnRH, resulting in elevated (P < .01) progesterone on d 0 for GnRH+NORG-treated cows. Concentrations of estradiol-17beta (P < .01) and LH (P < .05) were greater on d +2 after GnRH for cows previously receiving norgestomet implants. Pregnancy rates after one fixed-time AI at 16 h after GnRH (d +2) were greater (P < .05) in GnRH+NORG (71%) than in GnRH (31%) and NORG (15%) cows. Difference in pregnancy rate was due partly to normal luteal activity after AI in over 87% of GnRH+NORG cows and no incidence of short luteal phases. The GnRH+NORG treatment initially induced ovulation or turnover of the largest follicle, induction of a new follicular wave, followed later by increased concentrations of estradiol-17beta and progesterone. After PGF2alpha, greater GnRH-induced release of LH occurred in GnRH+NORG cows before ovulation, and pregnancy rates were greater after a fixed-time AI.


Subject(s)
Breeding/methods , Cattle/physiology , Dinoprost/pharmacology , Gonadotropin-Releasing Hormone/pharmacology , Ovarian Follicle/physiology , Pregnenediones/pharmacology , Progesterone Congeners/pharmacology , Animals , Animals, Suckling , Corpus Luteum/drug effects , Corpus Luteum/physiology , Estrus/drug effects , Estrus Synchronization , Female , Fertility/drug effects , Ovarian Follicle/drug effects , Postpartum Period , Pregnancy
18.
J Anim Sci ; 77(8): 2207-18, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10462001

ABSTRACT

Two experiments were conducted to determine whether milking beef cows two or five times daily in the presence or absence of their own nonsuckling calves would alter postpartum interval to first ovulation. Multiparous Angus x Hereford cow-calf pairs were assigned randomly between 13 and 18 d postpartum to treatments for 4 wk. In Exp. 1, pairs were assigned to six treatments: 1) calf was weaned permanently from its dam (CW; n = 9); 2) same as CW, but dam was milked twice daily (CW+2xM; n = 9); 3) calf was present continuously with its dam but restricted from contact with the udder (CR; n = 9); 4) same as CR, but dam was milked twice daily (CR+2xM; n = 9); 5) same as CR, but calf was allowed to suckle twice daily (CR+2xS; n = 8); and 6) calf was present continuously with its dam and suckled ad libitum (CP; n = 9). The interval from onset of treatments to first postpartum ovulation was shorter (P<.05) in the CW (14.1+/-3.1 d), CR (14.2+/-3.1 d), CW+2xM (13.0+/-3.1 d), and CR+2xM (17.2+/-3.1 d) than in the CP (34.7+/-3.1 d) and CR+2xS (33.9+/-3.3 d) treatments. Daily milk yield during treatment was greater (P<.01) for CR+2xM cows (7.1+/-.6 kg) than for CW+2xM cows (3.5+/-.6 kg). In Exp. 2, cow-calf pairs were assigned to three treatments: 1) CR+2xM (n = 10); 2) same as CR+2xM but cows were milked five times daily (CR+5xM; n = 10); or 3) CP (n = 10). The interval to first postpartum ovulation was shorter (P<.05) in the CR+2xM (23.6+/-3.5 d) and CR+5xM (26.1+/-3.7 d) treatments than in the CP (37.7+/-3.7 d) treatment. Daily milk yield during treatment was greater (P<.05) for CR+5xM cows (7.7+/-.6 kg) than for CR+2xM cows (6.4+/-.6 kg) by 17%. We conclude that suckling twice daily was sufficient to prolong postpartum anestrus as much as suckling ad libitum. Furthermore, milk removal by suckling, but not by milking two or five times daily, even in the presence of the cow's own nonsuckling calf, is essential to prolong postpartum anovulation.


Subject(s)
Anovulation , Cattle/physiology , Dairying/methods , Postpartum Period , Animals , Body Weight , Diet , Female , Luteinizing Hormone/blood , Milk/chemistry
19.
J Dairy Sci ; 82(7): 1489-96, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10416164

ABSTRACT

We determined whether milk secretion in beef cows could be reinitiated by renewed suckling after a hiatus from milking or suckling. Fifty-three Angus x Hereford cows were suckled ad libitum by their own calves for 13 to 18 d postpartum and then assigned to treatments for 4 wk in which cows were 1) neither milked nor suckled (weaned; n = 18), 2) milked 2 x daily (milked; n = 18), or 3) suckled by their own calves (suckled; n = 17). Thereafter, all calves (including earlier weaned calves) suckled their own dams until permanent weaning at 203 d of age, except when their dams were milked once after receiving (i.m.) 40 IU of oxytocin at reinitiation of suckling (0 wk) and again 1 and 5 wk later. Prolactin was increased in milked and suckled cows during 20 min after milking or suckling at the termination of treatments (0 wk). Concentrations of insulin-like growth factor-I were greater for weaned than suckled cows; milked cows had intermediate concentrations. At 0 wk, milk yield was greater for suckled than milked or weaned treatment cows. After 1 wk of renewed suckling, milk secretion of weaned treatment cows increased, and by 5 wk, composition of milk was normal, but yield was still reduced. We concluded that milk secretion was renewed by suckling in early postpartum cows after they were neither suckled nor milked for 4 wk.


Subject(s)
Animals, Suckling , Lactation/physiology , Milk/metabolism , Postpartum Period/physiology , Animals , Cattle , Female , Lactose/analysis , Lipids/analysis , Meat , Milk/chemistry , Milk Proteins/analysis , Prolactin/analysis
20.
Domest Anim Endocrinol ; 15(5): 389-96, 1998 Sep.
Article in English | MEDLINE | ID: mdl-9785043

ABSTRACT

Contained in this report is a review of available data on pituitary cytokines in domestic species of agricultural importance. The concept is advanced that the pituitary gland is essential to appropriate generation of host defense mechanisms and thus should be considered among other tissues contributing to innate immunity. The functions of these intrapituitary cytokines, principally IL-6, are discussed in the context of potential regulation of the pituitary-adrenal axis (ACTH secretion) via intrapituitary PGE2 generation during the acute-phase response to infectious/inflammatory stimuli. Data from other species are cited as appropriate for comparative purposes and elaboration of proposed mechanisms. However, the scope of the review is not intended to comprehensively cover the vast literature on proinflammatory cytokines and prostaglandins generated peripherally and centrally during host responses to inflammatory stimuli.


Subject(s)
Acute-Phase Reaction/veterinary , Adrenocorticotropic Hormone/metabolism , Animals, Domestic , Cytokines/immunology , Dinoprostone/immunology , Pituitary Gland, Anterior/immunology , Acute-Phase Reaction/immunology , Acute-Phase Reaction/physiopathology , Amino Acid Sequence , Animals , Cattle , Cytokines/physiology , Dinoprostone/physiology , Humans , Immunity, Innate/physiology , Indomethacin/pharmacology , Interleukin-6/immunology , Interleukin-6/physiology , Lipopolysaccharides/pharmacology , Macrophage Migration-Inhibitory Factors/immunology , Macrophage Migration-Inhibitory Factors/physiology , Mice , Molecular Sequence Data , Pituitary Gland, Anterior/metabolism , Pituitary Gland, Anterior/physiology , Pituitary-Adrenal System/immunology , Pituitary-Adrenal System/metabolism , Pituitary-Adrenal System/physiology , Rats , Sequence Homology, Amino Acid , Swine
SELECTION OF CITATIONS
SEARCH DETAIL
...