Protein Supplementation and Grazing Behavior for Cows on Differing Late-Season Rangeland Grazing Systems.

The objective was to determine if low- or high-residual feed intake (LRFI or HRFI, = 24 for each) Hereford × Angus cows on continuously or rotationally grazed rangeland altered their grazing behavior when provided a protein supplement in late autumn. Treatments included continuously grazed, control (CCON, = 12); continuously grazed, supplemented (CTRT, = 12); rotationally grazed, control (RCON, = 12); and rotationally grazed, supplemented pastures (RTRT, = 12). Cows in each treatment had grazing time (GT), resting time (RT), and walking time (WLK) measured for 2 years with accelerometers.

Variation in type two taste receptor genes is associated with bitter tasting phenylthiocarbamide consumption in mature Targhee and Rambouillet rams.

Bitter taste perception in sheep can lead to avoidance of specific types of forage, such as sagebrush, which is present on many rangeland grazing systems in the Intermountain West. In humans, bitter taste perception is influenced by variation in several TAS2R genes, including more extensively studied and . We hypothesize that variation in taste receptor genes in sheep is associated with bitter taste.

Grazing behavior and production for lactating cows differing in residual feed intake while grazing spring and summer rangeland.

The objectives were to determine if previously classified, efficient (LRFI, low-residual-feed intake, = 12 × 2 yr) vs. inefficient (HRFI, high-residual-feed intake, = 12 × 2 yr) lactating 2-yr-old Hereford × Angus cows differed in grazing behavior, body weight (BW), body condition score (BCS), and calf weaning weight while grazing rugged rangeland pastures. Cows were fitted with grazing halters containing both an accelerometer and a global positioning system (GPS) data logger during June 14 to July 4, 2016, August 2 to 25, 2016, May 23 to June 12, 2017, and August 5 to 28, 2017.

Avoidance of phenylthiocarbamide in mature Targhee and Rambouillet rams.

Shrub encroachment on grasslands is a worldwide issue and sheep are a potential tool for mitigating shrub encroachment. Many shrubs, however, contain bitter-tasting compounds that may deter grazers. Cattle and sheep commonly graze rangelands, but of the two, sheep have a greater tolerance for bitter compounds and would be expected to consume more bitter-tasting vegetation.

Comparison of long-term progestin-based protocols to synchronize estrus prior to natural service or fixed-time artificial insemination in Bos indicus-influenced beef heifers.

This experiment was designed to evaluate breeding strategies involving natural service or fixed-time artificial insemination (FTAI) in Bos indicus-influenced beef heifers (n = 1456) when there were field-type management conditions. Body weights and reproductive tract scores (RTS; Scale 1-5) were obtained for heifers before assignment to one of five treatments: 1) Non-synchronized control exposed for natural service (NS), n = 299; 2) melengestrol acetate + natural service (MGA + NS; 0.5 mg/heifer/d), n = 295; 3) 14-d controlled internal drug release insert + natural service (CIDR + NS), n = 289; 4) 14-d MGA-prostaglandin F (PG) + FTAI, n = 295; or 5) 14-d CIDR-PG + FTAI, n = 278.

Intake behaviors of yearling steers grazing irrigated pasture and receiving either a free-choice salt-based mineral or a low-moisture molasses-based tub mineral.

Mineral intake in grazing cattle is highly variable and research evaluating behavioral aspects of intake are minimal. Development of the GrowSafe System to monitor feed intake allows researchers to record individual feeding behaviors of cattle 24 h per day. In the current experiment conducted during June and July, the GrowSafe System was utilized to evaluate intake behaviors of grazing steers during a short-term free-choice supplementation of either salt-based loose minerals (; = 24; 408 ± 57 kg) or low-moisture molasses-based tub minerals (; = 24; 396 ± 64 kg).

Effect of increased inclusion of dried distillers grain supplement on adaptation, intake, digestibility, and rumen parameters in steers consuming bermudagrass round bale silage.

Eight ruminally cannulated beef steers were used to evaluate forage intake and physiological response during adaptation to a diet consisting of bermudagrass round bale silage (RBS) and dried distillers grains (DDG) and in a second experiment the effect of level of DDG supplementation on RBS forage intake, digestibility, and rumen parameters. The adaptation experiment was designed to simulate a 14-d step-up process. Initially steers received ad libitum RBS, on d 4 steers were offered 1.

Evaluation of the 14-d CIDR-PG and 9-d CIDR-PG protocols for synchronization of estrus in Bos indicus-influenced and Bos taurus beef heifers.

Two long-term, CIDR-based estrus synchronization protocols were evaluated among Bos indicus-influenced and Bos taurus beef heifers. Treatments were evaluated on the basis of estrous response and pregnancy rate resulting from fixed-time artificial insemination (FTAI), and these outcomes were analyzed retrospectively relative to reproductive tract score (RTS; Scale 1-5) at treatment initiation. Estrus was synchronized for 1139 heifers in three locations, and heifers were assigned to one of two treatments within each location based on RTS.

Comparison of wet brewers' grains or dried distillers' grains as supplements to conserved bermudagrass forage as winter feeding options for beef cows.

The objective of this study was to examine the use of 2 byproduct supplements and conserved warm-season forage as winter feeding options for primiparous beef cows. Gestating Angus ( = 48) and Brangus ( = 24) 2-yr-old cows were stratified by BW and breed to 1 of 12 pens. Pens were randomly assigned 1 of 2 supplements, wet brewers' grains (WBG) or dried distillers' grains (DDG).

Assessment of serum 25-hydroxyvitamin D concentrations of beef cows and calves across seasons and geographical locations.

Vitamin D is critical for the growth and development of calves and positively contributes to immune function of cattle. Serum 25-hydroxyvitamin D (25(OH)D) concentrations above 20 ng/mL have traditionally been considered adequate for growth and development of cattle, but recent evidence has indicated that concentrations below 30 ng/mL are insufficient for immunity. Because little information is available regarding vitamin D status of beef cattle, the objective of this study was to evaluate vitamin D status of beef cow-calf herds on pasture as affected by season and location.

Select Synch and Co-Synch protocols using a CIDR yield similar pregnancy rates after a fixed-time insemination in suckled Bos indicus × Bos taurus cows.

Primiparous and multiparous suckled Bos indicus × Bos taurus cows were used to compare a Select Synch + controlled internal drug release (CIDR) and timed artificial insemination (AI) protocol (SSC) to a modified CO-Synch + CIDR protocol (COS). Five separate groups of cows were utilized (n = 659) and within a group, cows were allotted to two treatments on the basis of body condition score (BCS) taken 10 days before and days postpartum at CIDR insertion (Day 0). Blood samples were collected on Day -10 and 0 for assessment of circulating concentrations of progesterone to determine estrous cycling status.

Comparison of feed additive technologies for preconditioning of weaned beef calves.

Our objective was to evaluate the response of weaned calves to different supplemental feed additives in a supplement to affect calf performance and mitigate stress response observed during weaning and preconditioning. At weaning in each of 2 yr, 160 Angus and Brangus calves (203 and 227 ± 2.3 and 2.

Subspecies differences in early fetal development and plasma pregnancy-associated glycoprotein concentrations in cattle.

Inclusion of Bos indicus genetics improves production traits of cattle maintained in hot climates. Limited information exists detailing pregnancy-specific events as influenced by variable amounts of Bos indicus genetics. Three experiments were completed to examine the effect of Bos taurus and Bos indicus genotypes on fetal size and plasma pregnancy-associated glycoprotein (PAG) concentrations.

Effect of castration technique on beef calf performance, feed efficiency, and inflammatory response.

The objective of this experiment was to examine the effect of castration technique on daily feed intake (DFI), daily water intake (DWI), growth performance, residual feed intake (RFI), and inflammatory response in weaned beef calves. Seventy-five beef calves (214 ± 3.2 kg; 200 ± 26 d of age) were housed in a GrowSafe 4000 feed intake facility 7 d post weaning (15 calves/pen).

Evaluation of two progestogen-based estrous synchronization protocols in yearling heifers of Bos indicus × Bos taurus breeding.

Yearling Bos indicus × Bos taurus heifers (n = 410) from three locations, were synchronized with either the Select Synch/CIDR+timed-AI (SSC+TAI) or 7-11+timed-AI (7-11+TAI) treatments. On Day 0 of the experiment, within each location, heifers were equally distributed to treatments by reproductive tract score (RTS; Scale 1-5: 1 = immature, 5 = estrous cycling) and body condition score. The 7-11+TAI treatment consisted of melengestrol acetate (0.

Effects of acclimation to handling on performance, reproductive, and physiological responses of Brahman-crossbred heifers.

The objective of this study was to evaluate the effects of acclimation to handling on growth, plasma concentrations of progesterone (P4) and cortisol, temperament, and reproductive performance of Brahman-crossbred heifers. Over 2 consecutive years, 37 Braford and 43 Brahman x Angus heifers were initially evaluated, within 30 d after weaning, for BW and puberty status via transrectal ultrasonography and plasma P4 concentrations (d 0 and 10), and for temperament by measurements of chute score, pen score, and exit velocity (d 10 only). On d 11, heifers were stratified by breed, puberty status, temperament score, BW, and age and randomly assigned to receive or not (control) the acclimation treatment.

Insulin-like growth factor (IGF) family genes are aberrantly expressed in bovine conceptuses produced in vitro or by nuclear transfer.

Embryos produced through somatic cell nuclear transfer (NT) or in vitro production (IVP) are often associated with increased abortion and abnormalities thought to arise from disruptions in normal gene expression. The insulin-like growth factor (IGF) family has a major influence on embryonic, fetal and placental development; differences in IGF expression in NT- and IVP-derived embryos may account for embryonic losses during placental attachment. In the present study, expression of IGF-I, IGF-II, IGF-I receptor (IGF-IR), and IGF-IIR mRNAs was quantitated in Day 7 and 25 bovine embryos produced in vivo, by NT, IVP, or parthenogenesis, to further understand divergent changes occurring during development.

Response to GnRH on day 6 of the estrous cycle is diminished as the percentage of Bos indicus breeding increases in Angus, Brangus, and Brahman x Angus heifers.

Angus (n=6), Brangus (5/8 Angus x 3/8 Brahman, n=6), and Brahman x Angus (3/8 Angus x 5/8 Brahman, n=6) heifers exhibiting estrous cycles at regular intervals were used to determine if the percentage of Bos indicus breeding influenced the secretory patterns of LH in response to a GnRH treatment on Day 6 of the estrous cycle. Heifers were pre-synchronized with a two-injection PGF(2 alpha) protocol (25 mg i.m.

Efficacy of either a single or split treatment of PGF2alpha after a 14 day melengestrol acetate treatment to synchronize estrus and induce luteolysis in Bos indicus x Bos taurus heifers.

Two experiments evaluated a modified delivery of prostaglandin F2alpha (PGF2alpha) after a melengestrol acetate (MGA) treatment in Angus and Bos indicus x Bos taurus (BI) heifers. Experiment 1 was replicated three times with yearling BI heifers (n = 695). Heifers received MGA (0.

Synchronization of Bos indicus x Bos taurus cows for timed artificial insemination using gonadotropin-releasing hormone plus prostaglandin F2alpha in combination with melengestrol acetate.

Nonlactating Bos indicus x Bos taurus cows were used in three herds to determine the efficacy of different PGF2alpha treatments in combination with GnRH and melengestrol acetate (MGA) for a timed artificial insemination protocol. The start of the experiment was designated as d 0, at which time cows were assigned a body condition score and received 100 microg of GnRH. Cows were fed MGA (0.