Control of parturition in hyperprolific sows by using altrenogest and double administrations of PGF2α.

The aim of the present study was to develop a protocol to reduce the variation in gestation length and synchronise the onset of parturition in sows by using altrenogest in combination with double administrations of prostaglandin F2alpha (PGF2α). In total, 188 Landrace x Yorkshire crossbred sows with parity numbers 3.1 ± 1.6 were included in the experiment. The sows were classified into two groups: CONTROL (n = 94) and TREATMENT (n = 94). CONTROL sows were allowed to farrow naturally, and TREATMENT sows were orally administered 20 mg/day of altrenogest starting when they entered the farrowing house (107.0 ± 2.0 days) until 113 (TREAT-113, n = 18), 114 (TREAT-114, n = 29) and 115 (TREAT-115, n = 47) days of gestation. The altrenogest-treated sows were administered PGF2α twice 6 h apart at 24 h after the withdrawal of altrenogest. The litters were randomly selected (25 and 26 litters from CONTROL and TREATMENT groups, respectively) to determine individual body weight at birth and at 24 h after birth. Gestation length of sows that farrowed naturally averaged 115.1 days (range 111-118), whereas gestation length of altrenogest-treated sows averaged 115.1-116.3 days (range 114-118). The colostrum yield of sows averaged 4.25 ± 1.19 kg and was not affected by the treatment (P > 0.05). Colostrum IgG in the CONTROL group was higher than in the TREAT-114 and TREAT-115 groups (P < 0.05) but did not differ significantly compared to the TREAT-113 group. The proportion of sows that farrowed during working hours (0700-1700 h) in the TREAT-113 group (72.3%) tended to be higher than in the CONTROL (46.4%, P = 0.053). The interval from the last altrenogest treatment until farrowing in the TREAT-113 group was longer than in the TREAT-114 and TREAT-115 groups (62.8, 40.7 and 34.6 h, respectively, P < 0.05). Similarly, the intervals from the first PGF2α administration to the onset of parturition in the TREAT-113 group (38.8 ± 3.8 h) was longer than TREAT-114 (21.9 ± 3.5 h, P = 0.002) and TREAT-115 (25.5 ± 3.7 h, P = 0.016) groups. However, the incidence of stillbirths in the TREAT-113, TREAT-114 and TREAT-115 groups was higher than in the CONTROL (16.4, 17.2, 11.8 and 5.8%, respectively, P < 0.05). In conclusion, altrenogest supplementation in combination with double administrations of PGF2α can reduce the variation in gestation length and synchronise the onset of parturition in sows. However, its side effects on the incidence of stillbirths should be considered.

Localization of kisspeptin, NKB, and NK3R in the hypothalamus of gilts treated with the progestin altrenogest.

Mechanisms in the brain controlling secretion of gonadotropin hormones in pigs, particularly luteinizing hormone (LH), are poorly understood. Kisspeptin is a potent LH stimulant that is essential for fertility in many species, including pigs. Neurokinin B (NKB) acting through neurokinin 3 receptor (NK3R) is involved in kisspeptin-stimulated LH release, but organization of NKB and NK3R within the porcine hypothalamus is unknown. Hypothalamic tissue from ovariectomized (OVX) gilts was used to determine the distribution of immunoreactive kisspeptin, NKB, and NK3R cells in the arcuate nucleus (ARC). Almost all kisspeptin neurons coexpressed NKB in the porcine ARC. Immunostaining for NK3R was distributed throughout the preoptic area (POA) and in several hypothalamic areas including the periventricular and retrochiasmatic areas but was not detected within the ARC. There was no colocalization of NK3R with gonadotropin-releasing hormone (GnRH), but NK3R-positive fibers in the POA were in close apposition to GnRH neurons. Treating OVX gilts with the progestin altrenogest decreased LH pulse frequency and reduced mean circulating concentrations of LH compared with OVX control gilts (P < 0.01), but the number of kisspeptin and NKB cells in the ARC did not differ between treatments. The neuroanatomical arrangement of kisspeptin, NKB, and NK3R within the porcine hypothalamus confirms they are positioned to stimulate GnRH and LH secretion in gilts, though differences with other species exist. Altrenogest suppression of LH secretion in the OVX gilt does not appear to involve decreased peptide expression of kisspeptin or NKB.

Supplemental progesterone during early pregnancy exerts divergent responses on embryonic characteristics in sows and gilts.

Progesterone (P4) plays a key role in pregnancy establishment and maintenance; during early pregnancy, P4 stimulates the production and release of uterine secretions necessary for conceptus growth prior to implantation; therefore, exogenous P4 supplementation may improve embryo development. This study evaluated the effects of supplementation during early pregnancy with long-acting injectable progesterone or altrenogest on embryonic characteristics of sows and gilts. Thus, a total of 32 sows and 16 gilts were used. On day 6 of pregnancy sows and gilts were allocated to one of the following groups: non-supplemented; supplemented with 20 mg of altrenogest, orally, from days 6 to 12 of pregnancy; supplemented with 2.15 mg/kg of long-acting injectable progesterone on day 6 of pregnancy. Animals were killed on day 28 of pregnancy, and ovulation rate, embryo survival, embryo weight, crown-to-rump length, uterine glandular epithelium and endometrial vascularization were assessed. Treatments had no effect on pregnancy rate, embryo survival or endometrial vascular density (P > 0.05). Non-supplemented gilts presented larger and heavier embryos compared to gilts from supplemented groups (P < 0.05). Sows in the altrenogest group presented larger and heavier embryos compared to non-supplemented sows and sows supplemented with long-acting injectable progesterone. In conclusion, supplementation of sows and gilts with progestagen from day 6 of pregnancy can be used as a means to improve embryo survival without deleterious effects.

Tissue explant coculture model of the hypothalamic-pituitary-gonadal-liver axis of the fathead minnow (Pimephales promelas) as a predictive tool for endocrine disruption.

Endocrine-disrupting compounds (EDCs) can impact the reproductive system by interfering with the hypothalamic-pituitary-gonadal (HPG) axis. Although in vitro testing methods have been developed to screen chemicals for endocrine disruption, extrapolation of in vitro responses to in vivo action shows inconsistent accuracy. The authors describe a tissue coculture of the fathead minnow (Pimephales promelas) HPG axis and liver (HPG-L) as a tissue explant model that mimics in vivo results. Brain (hypothalamus), pituitary, gonad, and liver tissue explants from adult fish were examined for function both individually and in coculture to determine combinations and conditions that could replicate in vivo behavior. Only cocultures had the ability to respond to an EDC, trenbolone, similarly to in vivo studies, based on estradiol, testosterone, and vitellogenin production trends, where lower exposure doses suppressed hormone production but higher doses increased production, resulting in distinctive U-shaped curves. These data suggest that a coculture system with all components of the HPG-L axis can be used as a link between in vitro and in vivo studies to predict endocrine system disruption in whole organisms. This tissue-based HPG-L system acts as a flexible deconstructed version of the in vivo system for better control and examination of the minute changes in system operation and response on EDC exposure with options to isolate, interrogate, and recombine desired components. Environ Toxicol Chem 2016;35:2530-2541. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

The effects of visceral obesity and androgens on bone: trenbolone protects against loss of femoral bone mineral density and structural strength in viscerally obese and testosterone-deficient male rats.

SUMMARY: In males, visceral obesity and androgen deficiency often present together and result in harmful effects on bone. Our findings show that both factors are independently associated with adverse effects on femoral bone structure and strength, and trenbolone protects rats from diet-induced visceral obesity and consequently normalises femoral bone structural strength. INTRODUCTION: In light of the rapidly increasing incidence of obesity and osteoporosis globally, and recent conjecture regarding the effects of visceral adiposity and testosterone deficiency on bone health, we investigated the effects of increased visceral adipose tissue (VAT) mass on femoral bone mineral density (BMD), structure and strength in normal weight rats with testosterone deficiency. METHODS: Male Wistar rats (n = 50) were fed either standard rat chow (CTRL, n = 10) or a high-fat/high-sugar diet (HF/HS, n = 40). Following 8 weeks of feeding, rats underwent sham surgery (CTRL, n = 10; HF/HS, n = 10) or orchiectomy (HF/HS + ORX, n = 30). Following a 4-week recovery period, mini-osmotic pumps containing either vehicle (CTRL, n = 10; HF/HS, n = 10; HF/HS + ORX, n = 10), 2.0 mg kg day(-1), testosterone (HF/HS + ORX + TEST, n = 10) or 2.0 mg kg day(-1) trenbolone (HF/HS + ORX + TREN, n = 10) were implanted for 8 weeks of treatment. Dual-energy X-ray absorptiometry and three-point bending tests were used to assess bone mass, structure and strength of femora. RESULTS: Diet-induced visceral obesity resulted in decreased bone mineral area (BMA) and content (BMC) and impaired femoral stiffness and strength. Orchiectomy further impaired BMA, BMC and BMD and reduced energy to failure in viscerally obese animals. Both TEST and TREN treatment restored BMA, BMC, BMD and energy to failure. Only TREN reduced visceral adiposity and improved femoral stiffness and strength. CONCLUSIONS: Findings support a role for both visceral adiposity and testosterone deficiency as independent risk factors for femoral osteoporosis, adverse bone geometry and impaired bone strength in male rats. Trenbolone may be a more effective candidate for androgen replacement therapy than testosterone in viscerally obese testosterone-deficient males.

Improvements in body composition, cardiometabolic risk factors and insulin sensitivity with trenbolone in normogonadic rats.

Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and continues to be misused for aesthetic purposes in humans. The current study investigated TREN's effects on body composition and cardiometabolic risk factors; and its tissue-selective effects on the cardiovascular system, liver and prostate. Male rats (n=12) were implanted with osmotic infusion pumps delivering either cyclodextrin vehicle (CTRL) or 2mg/kg/day TREN for 6 weeks. Dual-energy X-ray Absorptiometry assessment of body composition; organ wet weights and serum lipid profiles; and insulin sensitivity were assessed. Cardiac ultrasound examinations were performed before in vivo studies assessed myocardial susceptibility to ischemia-reperfusion (I/R) injury. Circulating sex hormones and liver enzyme activities; and prostate and liver histology were examined. In 6 weeks, fat mass increased by 34±7% in CTRLs (p<0.01). Fat mass decreased by 37±6% and lean mass increased by 11±4% with TREN (p<0.05). Serum triglycerides, HDL and LDL were reduced by 62%, 57% and 78% (p<0.05) respectively in TREN rats. Histological examination of the prostates from TREN-treated rats indicated benign hyperplasia associated with an increased prostate mass (149% compared to CTRLs, p<0.01). No evidence of adverse cardiac or hepatic effects was observed. In conclusion, improvements in body composition, lipid profile and insulin sensitivity (key risk factors for cardiometabolic disease) were achieved with six-week TREN treatment without evidence of adverse cardiovascular or hepatic effects that are commonly associated with traditional anabolic steroid misuse. Sex hormone suppression and benign prostate hyperplasia were confirmed as adverse effects of the treatment.

Biological responses of beef steers to steroidal implants and zilpaterol hydrochloride.

British × Continental steers (n = 168; 7 pens/treatment; initial BW = 362 kg) were used to evaluate the effect of dose/payout pattern of trenbolone acetate (TBA) and estradiol-17ß (E2) and feeding of zilpaterol hydrochloride (ZH) on serum urea-N (SUN), NEFA, IGF-I, and E2 concentrations and LM mRNA expression of the estrogen (ER), androgen (ANR), IGF-I (IGF-IR), ß1-adrenergic (ß1-AR), and ß2-adrenergic (ß2-AR) receptors and IGF-I. A randomized complete block design was used with a 3 × 2 factorial arrangement of treatments. Main effects were implant (no implant [NI], Revalor-S [REV-S; 120 mg TBA + 24 mg E2], and Revalor-XS [REV-X; 200 mg TBA + 40 mg E2]) and ZH (0 or 8.3 mg/kg of DM for 20 d with a 3-d withdrawal). Steers were fed for 153 or 174 d. Blood was collected (2 steers/pen) at d -1, 2, 6, 13, 27, 55, 83, 111, and 131 relative to implanting; LM biopsies (1 steer/pen) were collected at d -1, 27, 55, and 111. Blood and LM samples were collected at d -1, 11, and 19 relative to ZH feeding. A greater dose of TBA + E2 in combination with ZH increased ADG and HCW in an additive manner, suggesting a different mechanism of action for ZH and steroidal implants. Implanting decreased (P < 0.05) SUN from d 2 through 131. Feeding ZH decreased (P < 0.05) SUN. Serum NEFA concentrations were not affected by implants (P = 0.44). There was a day × ZH interaction (P = 0.06) for NEFA; ZH steers had increased (P < 0.01) NEFA concentrations at d 11 of ZH feeding. Serum E2 was greater (P < 0.05) for implanted steers by d 27. Serum trenbolone-17ß was greater (P < 0.05) for implanted steers by d 2 followed by a typical biphasic release rate, with a secondary peak at d 111 for REV-X (P < 0.05) implanted steers. Implanting did not affect mRNA expression of the ANR or ER, but the IGF-IR and the ß1-AR and ß2-AR were less (P < 0.05) for REV-S than NI at d 55 and ß2-AR mRNA was less (P < 0.05) for REV-S than for REV-X. Expression of the IGF-IR and the ß1-AR at d 111 was greater (P< 0.05) for REV-X than for REV-S and NI at d 111, and the ß2-AR was less (P< 0.05) for REV-S than for REV-X. Feeding ZH did not affect mRNA expression of the ß1-AR and ß2-AR. Both implanting and feeding ZH decreased SUN, but a greater dose of TBA + E2 did not result in further decreases. In addition, feeding ZH increased serum NEFA concentrations. Metabolic changes resulting from implanting and feeding ZH may aid in explaining steer performance and carcass responses to these growth promotants.

Additive effects of growth promoting technologies on performance of grazing steers and economics of the wheat pasture enterprise.

This research was designed to evaluate the effect of monensin (Elanco Animal Health, Greenfield, IN) supplementation via mineral or pressed protein block with or without a growth-promoting implant on performance of steers grazing wheat pasture in Arkansas over 2 yr. Preconditioned steers (n = 360, BW = 238 ± 5.1 kg) grazed 15 1.6-ha wheat pastures in the fall (n = 60 steers each fall, stocking rate of 2.5 steers/ha) or 30 0.8-ha wheat pastures in the spring (n = 120 steers each spring, stocking rate of 5 steers/ha). Steers in each pasture were given free-choice access to nonmedicated mineral (CNTRL; MoorMan's WeatherMaster Range Minerals A 646AAA; ADM Alliance Nutrition, Inc., Quincy, IL), or were supplemented with monensin (Elanco Animal Health, Greenfield, IN) via mineral containing 1.78 g monensin/kg (RMIN; MoorMan's Grower Mineral RU-1620 590AR; ADM Alliance Nutrition, Inc.), or pressed protein block containing 0.33 g monensin/kg (RBLCK; MoorMan's Mintrate Blonde Block RU; ADM Alliance Nutrition, Inc.). Additionally, one-half of the steers in each pasture were implanted (IMPL) with 40 mg trenbolone acetate and 8 mg estradiol (Component TE-G with Tylan; Elanco Animal Health). There was no interaction (P ≥ 0.71) between supplement treatment and growth-promoting implants, and ADG for RMIN and RBLCK were increased (P < 0.01) over CNTRL by 0.07 to 0.09 kg/d, respectively. Implanting steers with Component TE-G increased (P < 0.01) ADG by 0.14 kg/d. The combination of these growth-promoting technologies are a cost-effective means of increasing beef production by 22% without increasing level of supplementation or pasture acreage. Utilizing ionophores and implants together for wheat pasture stocker cattle decreased cost of gain by 26%. Utilizing both IMPL and monensin increased net return by $30 to $54/steer for RMIN or $18 to $43/steer for RBLCK compared with UNIMPL CNTRL at Low and High values of BW gain, respectively.

Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on longissimus muscle shear force and sensory attributes of calf-fed Holstein steers.

The effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on slice shear force (SSF) and sensory characteristics of beef from calf-fed Holstein steers was evaluated. All steers were implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to 1 of 4 treatments: control, RH fed at 300 mg·steer(-1)·d(-1) (RH 300) or RH fed at 400 mg·steer(-1)·d(-1)(RH 400) for the final 31 d of finishing, or ZH fed at 6.8 g/t for 21 d with a 5-d withdrawal before harvest. Fourteen carcasses were randomly selected from each pen, and two LM samples (1 per side) were excised and aged either 14 or 21 d before SSF testing. For trained panel evaluation, two steaks were collected from each of 60 low Choice strip loins (20 each from control, RH 300, and ZH treatments) and aged either 14 or 21 d. Steers fed RH and ZH produced steaks with SSF values that were 9% to 25% higher than controls. No difference in SSF was detected between the two levels of RH (P > 0.05). Compared to controls, the probability of steaks aged 14 d failing to meet SSF requirements to be certified tender (SSF < 20 kg) was increased 0.15, 0.17, and 0.26 in steers fed RH 300, RH 400, and ZH, respectively. Compared to controls, the probability of steaks aged 21 d having SSF values >20 kg was increased 0.03, 0.08, and 0.16 in steers fed RH 300, RH 400, and ZH, respectively. Steaks from Select carcasses of steers fed ZH aged 21 d postmortem had double the probability (0.39 vs. 0.17) of having SSF values >20 kg compared to steaks from steers fed either level of RH (P < 0.05). This difference tended to be identical in steaks from Select carcasses 14 d postmortem (0.50 vs. 0.33; P = 0.11); however, no difference was found in low Choice samples at 14 or 21 d postmortem. Trained panelists rated steaks aged 14 d from steers fed ZH lower for overall tenderness and flavor compared to controls (P < 0.05); however, no difference was found between controls and those fed RH 300. Steaks from steers fed ZH aged 21 d were rated lower for overall tenderness and juiciness compared to controls and those from steers fed RH 300 (P < 0.05). This study suggests RH and ZH negatively impact sensory attributes of beef from calf-fed Holstein steers.

Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on carcass cutability of calf-fed Holstein steers.

Effects of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on saleable yield of carcass sides from calf-fed Holstein steers were evaluated using steers implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg•steer(-1)/d(-1) (RH 300) or RH fed at 400 mg•steer(-1)/d(-1) (RH 400) the final 31 d of finishing, and ZH fed at 60 to 90 mg•steer(-1)/d(-1) (7.56 g/ton on a 100% DM basis) for 21 d with a 5 d withdrawal before harvest. Eight to nine carcass sides were randomly selected from each pen; carcass sides with excessive hide pulls, fat pulls or bruises were avoided. Cutout data were collected within a commercial facility using plant personnel to fabricate sides at a rate of one every 3 to 4 min into items typically merchandised by the facility. All lean, fat and bone were weighed and summed back to total chilled side weight with a sensitivity of ± 2% to be included in the data set. Compared to controls, ß-agonists increased saleable yield of whole-muscle cuts by 0.61%, 0.86% and 1.95% for RH 300, RH 400 and ZH, respectively (P < 0.05). Percent fat was less in carcasses from the ZH treatment compared to controls (P < 0.05); however, this difference was not observed between RH treatments and controls (P > 0.05). Percent bone was less in the ZH treatment due to increased muscle (P < 0.05). The percent of chilled side weight comprised of trimmings was unchanged between treatments, but on a 100% lean basis, RH 400 and ZH increased trim yields (P < 0.05). Analysis of saleable yield by primal showed a fundamental shift in growth and development. Beta-agonists caused a shift in proportion of saleable yield within individual primals, with a greater portion produced from the hindquarter relative to the forequarter, specifically in those muscles of the round (P < 0.05). Beta-agonists increased saleable yield, but these effects were not constant between all major primals. The cutout value gained by packers as a result of ß-agonist use may be influenced more by reduced fatness and increased absolute weight if musculature is primarily increased in the lower priced cuts of the carcass.

Custom microarray construction and analysis for determining potential biomarkers of subchronic androgen exposure in the Eastern Mosquitofish (Gambusia holbrooki).

BACKGROUND: The eastern mosquitofish (Gambusia holbrooki) has the potential to become a bioindicator organism of endocrine disrupting chemicals (EDCs) due to its androgen-driven secondary sexual characteristics. However, the lack of molecular information on G. holbrooki hinders its use as a bioindicator coupled with biomarker data. While traditional gene-by-gene approaches provide insight for biomarker development, a holistic analysis would provide more rapid and expansive determination of potential biomarkers. The objective of this study was to develop and utilize a mosquitofish microarray to determine potential biomarkers of subchronic androgen exposure. To achieve this objective, two specific aims were developed: 1) Sequence a G. holbrooki cDNA library, and 2) Use microarray analysis to determine genes that are differentially regulated by subchronic androgen exposure in hepatic tissues of 17ß-trenbolone (TB) exposed adult female G. holbrooki. RESULTS: A normalized library of multiple organs of male and female G. holbrooki was prepared and sequenced by the Illumina GA IIx and Roche 454 XLR70. Over 30,000 genes with e-value ≤ 10⁻4 were annotated and 14,758 of these genes were selected for inclusion on the microarray. Hepatic microarray analysis of adult female G. holbrooki exposed to the vehicle control or 1 µg/L of TB (a potent anabolic androgen) revealed 229 genes upregulated and 279 downregulated by TB (one-way ANOVA, p < 0.05, FDR α = 0.05, fold change > 1.5 and < -1.5). Fifteen gene ontology biological processes were enriched by TB exposure (Fisher's Exact Test, p < 0.05). The expression levels of 17ß-hydroxysteroid dehydrogenase 3 and zona pellucida glycoprotein 2 were validated by quantitative polymerase chain reaction (qPCR) (Student's t-test, p < 0.05). CONCLUSIONS: Coupling microarray data with phenotypic changes driven by androgen exposure in mosquitofish is key for developing this organism into a bioindicator for EDCs. Future studies using this array will enhance knowledge of the biology and toxicological response of this species. This work provides a foundation of molecular knowledge and tools that can be used to delve further into understanding the biology of G. holbrooki and how this organism can be used as a bioindicator organism for endocrine disrupting pollutants in the environment.

Relationship of whole body nitrogen utilization to urea kinetics in growing steers.

Urea kinetics were measured in 2 experiments, with treatments designed to change protein deposition by the animal. Our hypothesis was that increased protein deposition by cattle (Bos taurus) would reduce urea production and recycling to the gastrointestinal tract. Urea kinetics were measured by continuous intravenous infusion of (15)N(15)N-urea followed by measurement of enrichment in urinary urea at plateau. In Exp. 1, 6 steers (139 kg) were maintained in a model in which leucine was the most limiting AA. Treatments were arranged as a 2 × 3 factorial and were provided to steers in a 6 × 6 Latin square design. Leucine treatments included 0 or 4 g/d of abomasally supplemented L-leucine, and energy treatments included control, abomasal glucose infusion (382 g DM/d), or ruminal VFA infusion (150 g/d of acetic acid, 150 g/d of propionic acid, and 50 g/d of butyric acid). Leucine supplementation increased (P < 0.01) N retention, and energy supplementation tended to increase (P = 0.09) N retention without differences between glucose and VFA supplements (P = 0.86). Energy supplementation did not strikingly improve the efficiency of leucine utilization. Although both leucine and energy supplementation reduced urinary urea excretion (P ≤ 0.02), treatments did not affect urea production (P ≥ 0.34) or urea recycling to the gut (P ≥ 0.30). The magnitude of change in protein deposition may have been too small to significantly affect urea kinetics. In Exp. 2, 6 steers (168 kg) were maintained in a model wherein methionine was the most limiting AA. Steers were placed in 2 concurrent 3 × 3 Latin squares. Steers in one square were implanted with 24 mg of estradiol and 120 mg trenbolone acetate, and steers in the other square were not implanted. Treatments in each square were 0, 3, or 10 g/d of L-methionine. Implantation numerically improved N retention (P = 0.13) and reduced urea production rate (P = 0.03), urinary urea excretion (P < 0.01), and urea recycling to the gastrointestinal tract (P = 0.14). Effects of methionine were similar to implantation, but smaller in magnitude. When protein deposition by the body is increased markedly, ruminally available N in the diet may need to be increased to offset reductions in urea recycling.

17ß-Hydroxyestra-4,9,11-trien-3-one (Trenbolone) preserves bone mineral density in skeletally mature orchiectomized rats without prostate enlargement.

Testosterone enanthate (TE) administration attenuates bone loss in orchiectomized (ORX) rats. However, testosterone administration may increase risk for prostate/lower urinary tract related adverse events and polycythemia in humans. Trenbolone enanthate (TREN) is a synthetic testosterone analogue that preserves bone mineral density (BMD) and results in less prostate enlargement than testosterone in young ORX rodents. The purpose of this experiment was to determine if intramuscular TREN administration attenuates bone loss and maintains bone strength, without increasing prostate mass or hemoglobin concentrations in skeletally mature ORX rodents. Forty, 10 month old male F344/Brown Norway rats were randomized into SHAM, ORX, ORX+TE (7.0mg/week), and ORX+TREN (1.0mg/week) groups. Following surgery, animals recovered for 1 week and then received weekly: vehicle, TE, or TREN intramuscularly for 5 weeks. ORX reduced total and trabecular (t) BMD at the distal femoral metaphysis compared with SHAMs, while both TREN and TE completely prevented these reductions. TREN treatment also increased femoral neck strength by 28% compared with ORX animals (p<0.05), while TE did not alter femoral neck strength. In addition, TE nearly doubled prostate mass, compared with SHAMs (p<0.05). Conversely, TREN induced a non-significant 20% reduction in prostate mass compared with SHAMs, ultimately producing a prostate mass that was 64% below that found in ORX+TE animals (p<0.01). Hemoglobin concentrations and levator ani/bulbocavernosus (LABC) muscle mass were elevated in ORX+TE and ORX+TREN animals to a similar degree above both SHAM and ORX conditions (p<0.01). In skeletally mature rodents, both high-dose TE and low-dose TREN completely prevented the ORX-induced loss of tBMD at the distal femoral metaphysis and increased LABC mass. TREN also augmented femoral neck strength and maintained prostate mass at SHAM levels. These findings indicate that TREN may be an advantageous agent for future clinical trials evaluating agents capable of preventing bone loss resulting from androgen deficiency.

17ß-Hydroxyestra-4,9,11-trien-3-one (trenbolone) exhibits tissue selective anabolic activity: effects on muscle, bone, adiposity, hemoglobin, and prostate.

Selective androgen receptor modulators (SARMs) now under development can protect against muscle and bone loss without causing prostate growth or polycythemia. 17ß-Hydroxyestra-4,9,11-trien-3-one (trenbolone), a potent testosterone analog, may have SARM-like actions because, unlike testosterone, trenbolone does not undergo tissue-specific 5α-reduction to form more potent androgens. We tested the hypothesis that trenbolone-enanthate (TREN) might prevent orchiectomy-induced losses in muscle and bone and visceral fat accumulation without increasing prostate mass or resulting in adverse hemoglobin elevations. Male F344 rats aged 3 mo underwent orchiectomy or remained intact and were administered graded doses of TREN, supraphysiological testosterone-enanthate, or vehicle for 29 days. In both intact and orchiectomized animals, all TREN doses and supraphysiological testosterone-enanthate augmented androgen-sensitive levator ani/bulbocavernosus muscle mass by 35-40% above shams (P ≤ 0.001) and produced a dose-dependent partial protection against orchiectomy-induced total and trabecular bone mineral density losses (P < 0.05) and visceral fat accumulation (P < 0.05). The lowest doses of TREN successfully maintained prostate mass and hemoglobin concentrations at sham levels in both intact and orchiectomized animals, whereas supraphysiological testosterone-enanthate and high-dose TREN elevated prostate mass by 84 and 68%, respectively (P < 0.01). In summary, low-dose administration of the non-5α-reducible androgen TREN maintains prostate mass and hemoglobin concentrations near the level of shams while producing potent myotrophic actions in skeletal muscle and partial protection against orchiectomy-induced bone loss and visceral fat accumulation. Our findings indicate that TREN has advantages over supraphysiological testosterone and supports the need for future preclinical studies examining the viability of TREN as an option for androgen replacement therapy.

Altrenogest treatment during late pregnancy did not reduce colostrum yield in primiparous sows.

The decrease in circulating concentrations of progesterone is the lactogenic trigger in many species. The aim of the present study was to determine the effect of an orally active progestogen, altrenogest, administered in late gestation, on lactogenesis in sows. Gilts were treated with altrenogest (20 mg/d) from d 109 to 112 of gestation (ALT112, n = 6) or d 113 (ALT113, n = 8) or were not treated (control, n = 9). Colostrum production, estimated from the BW gains of the piglets, was measured during 24 h starting at the onset of parturition. Colostrum samples were collected at the onset of parturition until 48 h later. Jugular blood samples were taken from d -8 prepartum until d 3 postpartum. Altrenogest treatment extended the gestation length of ALT113 sows in comparison with control sows (116.3 vs. 114.7 d; P < 0.05). Litter size and litter weight at birth did not differ between groups (P > 0.1). Estimated colostrum yield was not reduced in altrenogest-treated sows compared with control sows (4.20 kg) and tended to be greater in ALT112 (4.73 kg) than in ALT113 sows (3.74 kg; P = 0.09). Altrenogest reduced endogenous progesterone concentrations during the 2 d prepartum in ALT113 relative to control sows (P < 0.05), likely because luteolysis occurred earlier in relation to parturition in ALT113 sows. Altrenogest reduced estradiol-17beta concentrations during the 2 d prepartum in ALT113 (P < 0.05) and ALT112 (P < 0.1) sows. Altrenogest treatment did not influence the timing of the prepartum peak of prolactin in relation to parturition. The ALT113 sows had lesser (P < 0.05) concentrations of lactose in plasma and a lesser Na:K ratio in colostrum after parturition than Control and ALT112 sows, indicating that the junctions between their mammary epithelial cells were tighter. Concentrations of colostral IgG in sows that received altrenogest tended to be less than in control sows (P = 0.08). In conclusion, altrenogest administered from d 109 to 112 or 113 of pregnancy did not affect lactogenesis in sows, possibly because the treatment delayed farrowing and main hormonal changes without affecting the relative chronology of these changes.

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs.

Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P < 0.01) by 25 and 21%, respectively, compared with steers reared on grass silage alone and not treated with growth promotants. Except for HCW (P < 0.01), the use of growth promotants did not affect carcass measurements. Increasing the proportion of barley in the diet of steers finished on forage produced a heavier HCW (P < 0.01) and a greater (P < 0.01) quality grade. Because of their lower HCW and quality grade, cattle targeted to a forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.

Effect of flax supplementation and growth promotants on lipoprotein lipase and glycogenin messenger RNA concentrations in finishing cattle.

Lipoprotein lipase (LPL) hydrolyzes triacylglycerols into monoacylglycerol and fatty acids, which are taken up by tissues and used for energy. Glycogenin is the core protein on which glycogen molecules are synthesized. There is one molecule of glycogenin per molecule of glycogen in skeletal muscle; therefore, glycogen storage is limited by the amount of glycogenin present in muscle. The objective of this study was to investigate the effect of feeding flaxseed, a source of PUFA, and administering a growth promoter on steady-state LPL and glycogenin mRNA content of muscle in finishing cattle. Sixteen crossbred steers (initial BW = 397 kg), given ad libitum access to a 92% concentrate diet for 28 d, were used in a four-treatment, 2 x 2 factorial experiment, with flaxseed supplementation (0 or 5% of dietary DM) and implanting (not implanted or implanted with Revalor-S) as the main effects. Muscle biopsies were obtained from the LM at 0, 14, and 28 d, and used to quantify LPL and glycogenin mRNA concentrations using real-time quantitative PCR. Implanting with Revalor-S did not affect LPL (P = 0.13) or glycogenin (P = 0.98) mRNA concentrations. A day x flaxseed interaction (P < 0.001) was observed for both LPL and glycogenin mRNA concentrations. No differences (P > 0.10) were observed between 0 and 5% flaxseed supplemented steers; however, at 28 d, nonflaxseed-fed steers had 4.1- and 5.7-fold increases (P < 0.001) over flaxseed steers for LPL and glycogenin mRNA concentrations, respectively. To further evaluate the effects of alpha-linolenic acid (alpha-LA) on LPL and glycogenin mRNA concentrations, muscle satellite cells were isolated from five finishing steers, and different alpha-LA concentrations were applied in culture. The RNA was isolated from the bovine satellite cells. Addition of alpha-LA numerically increased (P = 0.16) the LPL mRNA concentration 48% at 1 microM alpha-LA compared with the control. The expression of glycogenin was increased (P < 0.05) 50% at 1 microM alpha-LA compared with the control. These results suggest that flaxseed supplementation to finishing steers for 28 d decreased gene expression of both LPL and glycogenin compared with not feeding flaxseed. Alterations in local concentrations of these two proteins could affect the ability of muscle to use fatty acids and glucose for energy, and, ultimately, affect carcass quality.

Effects of flax supplementation and a combined trenbolone acetate and estradiol implant on circulating insulin-like growth factor-I and muscle insulin-like growth factor-I messenger RNA levels in beef cattle.

We evaluated effects of a 5% (dry matter basis) ground flaxseed supplement (flax) and a trenbolone acetate and estradiol-17beta implant, Revalor-S, on circulating IGF-I and muscle IGF-I messenger RNA (mRNA). Sixteen crossbred yearling steers (initial BW = 397 kg) were assigned randomly to one of four treatments: 1) flax/implant; 2) nonflax/implant; 3) flax/nonimplant; and 4) nonflax/nonimplant. Serum was harvested from blood collected on d 0 (before implant or flax addition), 14, and 28, and used in subsequent analyses of circulating IGF-I. Biopsy samples (0.5 g) were obtained from the longissimus muscle on d 0, 14, and 28. Total RNA was isolated from the muscle samples, and real-time quantitative-PCR was used to assess relative differences in IGF-I mRNA. Flax supplementation had no effect (P > 0.10) on circulating IGF-I concentrations. Following implantation, sera from implanted steers had 52 and 84% greater (P < 0.05) IGF-I concentrations than sera from nonimplanted steers on d 14 and 28, respectively. On d 28, local muscle IGF-I mRNA levels increased 2.4-fold (P < 0.01) in biopsy samples obtained from implanted compared with nonimplanted steers. Muscle biopsy samples from nonflax cattle had 4.4-fold higher (P < 0.01) levels of IGF-I mRNA than those from flax cattle on d 28. To determine whether a component of flax, alpha-linolenic acid (alphaLA), was directly responsible for IGF-I mRNA down-regulation, we incubated primary cultures of bovine satellite cells, from implanted and nonimplanted steers, in two concentrations of alphaLA (10 nM and 1 microM). An implant x dose interaction (P < 0.05) was observed for IGF-I mRNA concentrations in bovine satellite cells cultured for 72 h with alphaLA. Satellite cells from nonimplanted steers had similar (P > 0.10) IGF-I mRNA concentration regardless of the level of alphaLA exposure; however, satellite cells from implanted steers exposed to 10 nM and 1 microM alphaLA had 2.5- and 2.0-fold greater IGF-I mRNA levels, respectively, than cells from implanted steers that were not exposed to alphaLA (P < 0.05). Administration of a Revalor-S implant increased circulating IGF-I and local muscle IGF-I mRNA concentrations in finishing cattle. However, muscle IGF-I mRNA levels were decreased by flax supplementation. Muscle cell culture experiments suggested that alphaLA was not responsible for the IGF-I mRNA down-regulation.

The effects of grazing, liquid supplements, and implants on feedlot performance and carcass traits of Holstein steers.

In each of 2 yr, 20 Holstein steers (185+/-7 kg initial BW) were allocated to each of three treatments: pastured for 4.5 mo on grass/legume pastures and then fed 80% corn diets (DM basis) until slaughter; pastured for 4.5 mo on grass/legume pastures with ad libitum access to molasses-based protein supplements and fed 80% corn diets until slaughter; and placed in a feedlot and fed only 80% corn diets until slaughter (FEEDLOT). Half of the steers in each treatment were initially implanted with Revalor-S and not reimplanted. Supplemented steers on pasture had greater (P < 0.05) ADG than unsupplemented steers, and FEEDLOT steers gained faster and were fatter (P < 0.05) after 4.5 mo. Implanted steers had greater (P < 0.05) ADG with no significant treatment x implant status effect. Supplement intake was variable and related to ambient temperature. During the feedlot phase, steers previously on pasture had greater DMI and ADG (P < 0.05) but were not more efficient than FEEDLOT steers. Percentage of USDA Choice carcasses, fat thickness, dressing percentage, yield grade, and final weight were greater (P < 0.05) for FEEDLOT steers than for steers on other treatments. Implanting increased ADG of all steers but did not affect carcass traits, carcass composition, or feedlot performance during the finishing phase. Holstein steers consuming supplemented and unsupplemented pasture before slaughter will be leaner, have lower carcass weights, and have generally lower quality grades than those fed exclusively in a feedlot when slaughtered at similar ages.

Reduction of energy requirements of steers fed on low-quality-roughage diets using trenbolone acetate.

1. Six steers implanted with 300 mg trenbolone acetate and six steers not implanted were fed on low protein, low-quality-roughage diets ad lib. in two experiments. The steers were Hereford (Bos taurus) x Brahman (Bos indicus) crossbreds (50:50), initially of about 400 kg mean live weight (LW). In the first experiment of 8 weeks duration roughage was given alone. In the second experiment of 6 weeks duration the diet was supplemented with 100 g urea and 4.6 g sulphur daily. The same steers were implanted in each experiment. At the conclusion of each experiment metabolic rate was measured after a 72 h fast. 2. In the first experiment control and implanted steers had similar rates of LW loss (0.57 and 0.59 kg/d respectively). Implanted steers had significantly (P less than 0.01) lower feed intakes (12.8 v. 10.9 g dry matter (DM)/kg LW), significantly (P less than 0.01) lower fasting metabolic rates even after adjustment for intake (83.3 v. 74.5 kJ/kg per d) and significantly (P less than 0.01) lower plasma insulin concentrations (24 v. 19 mu units/ml). Differences in plasma concentrations of free 3,5,3'-triiodothyronine (T3), non-esterified fatty acids and urea-nitrogen were not significant. 3. In the second experiment intake of the supplemented diet was similar in both control and trenbolone acetate-treated steers (19.5 and 20.0 g DM/kg LW respectively). LW gains were 0.23 and 0.41 kg/d for control and implanted steers respectively, the difference being significant (P less than 0.05). Fasting metabolic rate (76.9 v. 70.7 kJ/kg per d) was significantly (P less than 0.05) lower in implanted steers.