The Effects of Harvest Maturity of Eragrostis tef 'Moxie' Hay and Supplemental Energy Source on Forage Utilization in Beef Heifers

The phenological stage of maturity of grasses and supplementation program can impact forage utilization in grazing beef cattle. However, the potential interaction between harvest maturity of Eragrostis tef (teff) hay and energy supplement source was yet to be fully evaluated. Therefore, our objective was to determine the effects of harvest maturity of teff hay and supplemental energy sources on nutrient intake, apparent total-tract nutrient digestion, nitrogen (N) utilization, and ruminal fermentation characteristics in beef heifers. A split-plot design with teff hay harvest maturity as the whole plot and supplemental energy source as the subplot was administered in a three-period (21 d), three × three Latin square design. Six crossbred beef heifers (804 ± 53.6 kg of body weight; BW) were allocated to two harvest maturities (early- (EH]) or late-heading (LH)) and to two supplemental energy sources (no supplement (CON), or rolled corn grain or beet pulp pellet fed at 0.5% of BW). Data were analyzed using SAS. There was no harvest maturity × energy supplement interaction. Although harvest maturity had no impact on total dry matter intake (DMI), crude protein (CP) intake was greater (p < 0.01) for EH than LH heifers. Total intakes of dry (DM) and organic matter (OM) were also greater (p < 0.01) for supplemented than CON heifers, whereas acid detergent fiber (ADF) intake was greater for beet pulp heifers compared to heifers fed the CON diet and supplemental corn grain. Harvest maturity had no impact on ruminal pH. However, mean ruminal pH was lower (p = 0.04), duration pH < 6.2, and molar proportions of butyrate and branched-chain fatty acids were greater (p ≤ 0.049) for heifers fed corn grain compared to CON and beet pulp diets. Heifers fed EH hay had greater (p ≤ 0.02) apparent total-tract DM, OM, CP, NDF, and ADF digestibility than heifers fed LH hay. Although there was no supplemental energy effect on microbial nitrogen (N) flow, it was greater (p < 0.01) for EH than LH heifers. Apparent N retention, which did not differ, was negative across all diets. In summary, delaying the harvest of teff hay from the EH to LH stage of maturity compromised nutrient supply, which was not attenuated by feeding supplemental corn grain and beet pulp at 0.5% of diet DM. Because N retention was negative across harvest maturity, there might be a need to provide both energy and protein supplements to improve growth performance when feeding teff hay to beef cattle.

Effect of a lactobacillus fermentation product on postweaning heifer performance

The objective of the experiment was to compare the effect of dietary inclusion of a prebiotic fermentation product of Lactobacillus acidophilus (LaP, RumaCell; 5 mL•animal -1•d -1) or monensin on performance of replacement beef heifers. Heifers received a total mixed ration containing either LaP (n =77) or monensin (MON; Rumensin; 200 mg•animal -1•d -1; n = 79). Heifers were fed for 71 days in a GrowSafe unit so individual feed intake could be measured. Heifers were weighed every two weeks and feed efficiency calculated by residual feed intake (RFI). At the end of the RFI trial, heifers remained on their diets for an additional 27 days and were estrus synchronized using the 14-d CIDR + PG protocol and bred by artificial insemination (AI) followed by natural service. Prior to estrous synchronization reproductive tract scores (RTS; 1 = infantile to 5 = cycling/presence of corpus luteum) were measured. Continuous variables were analyzed using generalized mixed models whereas categorical data were analyzed by logistic regression. Body weights, average daily gain, feed intake and RFI value were similar (P &gt; 0.30) among MON and LaP supplemented heifers. Across treatments heifers gained 0.9 ± 0.1 kg/d while consuming 9.3 ± 0.5 kg of diets daily. Reproductive development as indicated by RTS was similar (P &gt; 0.28) between treatments. However, estrus response increased (P &lt; 0.01) and AI pregnancy rates tended to be greater (P &lt; 0.07) for MON compared to LaP heifers. In contrast, the percentage of heifers pregnant by 60 d and 100 d (80.4% and 90.5%, respectively) were not different (P &gt; 0.33) for MON and LaP heifers. In conclusion, addition of LaP to replacement heifer diets may result in growth and reproductive performance similar to an ionophore, if dietary energy is adequate for normal heifer growth.

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

Simple Summary

Cattle grazing late-season dormant rangeland are subject to impaired production due to reduced forage digestibility and a longer residence time of forage in the rumen, leading to reduced forage intake. It is a common practice to provide supplemental protein to help counteract these effects and to improve animal well-being and livestock production. Yet, the usage of supplements has been shown to interrupt and reduce the time spent grazing. These behavioral changes may vary with climate and the frequency and timing of strategic supplementation. The objective of this study was to evaluate how protein supplementation altered grazing behavior when used in both rotationally and continuously grazed dormant pastures. We utilized accelerometers (used in rockets to measure velocity in three directions and in smart phones to rotate the screen) to evaluate cattle behavior (via head movements) every 5 s on a 24 h basis. The cattle altered their grazing behavior in response to climate, supplementation status, and the grazing system. Cattle that were deprived of the protein supplement and stayed in the same continuously grazed pasture showed more restlessness in their behavior, spending more time walking from midnight to 8 a.m. Additionally, the harvest rate of dormant forage increased for the supplemented cattle.

Abstract

The objective was to determine if low- or high-residual feed intake (LRFI or HRFI, n = 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, n = 12); continuously grazed, supplemented (CTRT, n = 12); rotationally grazed, control (RCON, n = 12); and rotationally grazed, supplemented pastures (RTRT, n = 12). Cows in each treatment had grazing time (GT), resting time (RT), and walking time (WLK) measured for 2 years with accelerometers. Bite rate (BR) was also measured. Time distributions of GT and RT differed by year (p < 0.05), being influenced by colder temperatures in 2016. Cattle in 2016 spent more time grazing during early morning and late evening (p < 0.05) and rested more during the day (p < 0.05). In 2017, cattle in the CCON treatment walked more (p < 0.05) during early morning time periods than did the CTRT cattle, indicative of search grazing. All supplemented cattle had greater BR (p < 0.05) than control cattle in 2017. Cattle with increased nutritional demands alter grazing behavior in a compensatory fashion when grazing late-season rangelands.

260 Effect of Dam Nutrition on Offspring Reproductive Performance

Domestic ruminants utilize extensive pasture and rangelands as a primary source of nutrition. These forage sources vary greatly in nutritional content and availability due to season, plant species and climatic factors. Therefore, ruminants are exposed to nutrient excesses and deficiencies at varying points during the reproductive cycle. The objectives of this presentation are 1) to review our understanding of the impact of nutritional changes experienced by the dam during gestation on subsequent reproductive performance of female offspring, 2) examine the timing and duration of nutrient restriction on indicators of fertility in domestic ruminants and 3) compare responses under production conditions to mechanisms determined in controlled experiments. Depending on the time and severity of the nutrient deprivation, physiological effects include reduced gonadal weight, reduction in 2° and 3° follicles, alterations in the hypothalamic-pituitary axis, fetal weight and attainment of puberty. Anti-Müllerian hormone (AMH) and antral follicle count (AFC) are indicators of fertility in ruminants. Severe nutrient deprivation of heifers during the first trimester of gestation reduced AMH and AFC in female offspring. In contrast, a more moderate nutritional challenge to mature cows during early gestation did not result in changes in AMH and AFC in female offspring. Heifers from dams that grazed protein deficient range during the third trimester had delayed puberty onset and reduced pregnancy rates compared to heifers from supplemented dams. Recently, we compared indictors of fertility in heifers from dams that grazed range or irrigated pastures during the first two trimesters. Based on preliminary data, cows that grazed range were nutritionally challenged; however, heifers from range dams did not appear to differ in indicators of fertility from heifers from dams grazing irrigated pastures. Continued investigations on impacts of maternal nutrition on reproduction in offspring under production conditions are warranted.

PSI-18 Identifying genetic variants associated with grazing, walking, and slope use of cattle experiencing mild heat load

Rangeland is a valuable resource that can allow producers to cost effectively provide nutrients for grazing cattle. However, grazing behavior of cattle is adversely affected when the temperature humidity index is greater than 72. It is possible to select cattle that exhibit efficient grazing behavior even under mild heat stress. This study evaluated genetic associations with grazing behavior to help producers identify cows that will effectively use their rangeland pastures. Using genome-wide associations, this study identified single nucleotide polymorphisms (SNPs) associated with grazing time, walking time and max slope that cattle utilized while experiencing mild heat load. Data were collected from Angus X Hereford 2-year-old beef cows from UI herd over two years (37 grazing and walking minutes, 38 max slope). Genotypes were obtained using a Bovine GGP 50K SNP marker array and 41,686 markers were used in the analyses. Two SNPs on chromosome 11 are significantly (P = 5.01e-7, P = 6.46e-7) associated with grazing minutes and explain 0.52 proportion of variance (PVE). A SNP on chromosome 3 is significant for walking minutes (P=1.91e-6) with a PVE of 0.48. Additionally, a SNP on chromosome 14 is significantly (P = 8.50e-6) associated with max slope and has a PVE of 0.43. This ongoing project identified significant associations with grazing and walking minutes and maximum slope. This research will be strengthened with the addition of more animals over successive years. Some cattle spend more time grazing, walking, or at a higher elevation in mild heat load. Identifying genetic variants associated with grazing time, walking time, and maximum slope use while under heat stress can enable producers to select for cattle that best fit the rangeland available to them.

234 Pregnancy and Hormonal Response in Suckled Beef Cows Administered High-concentration Prostaglandin F2α in a 5-day CO-Synch + CIDR Synchronization Program

Two injections of prostaglandin F2 (PGF) in a 5-d CO-Synch+CIDR timed-AI protocol (5-d CIDR) is necessary to induce luteolysis and reduce serum progesterone (P4) concentrations by the time of AI in beef cattle. The objectives were to examine the effects of a single high-concentration dose of PGF in a 5-d CIDR protocol on P4 concentration and pregnancy per AI (P/AI) beef cows. Angus-Hereford cows (n = 404) were synchronized (d0) with a 5-d CIDR protocol and assigned to receive either one injection of high-concentration PGF on d5 (HC; total dose: 25 mg; n = 203) or two injections of conventional PGF (2PG; each injection: 25 mg; n = 201), at CIDR removal (d5) and 8 h later. All cows received AI at a fixed time 72 h after PGF treatment (d8). Pregnancy was determined by ultrasound 48–63 days after AI. For P4 and cyclicity determination, blood samples were collected on d -7, 0, and 8. Cyclicity status and proportion of cows with a CL at d0 did not differ between treatments. Proportion of cows detected in estrus was greater (P = 0.01) for 2PG (63.1%) than HC (49.3%). Treatment did not affect P/AI (P = 0.87; 51% vs. 52% for HC and 2PG, respectively). Serum P4 at AI also affected (P &lt; 0.01) P/AI; as P4 concentration increased, P/AI decreased. ROC analysis showed a greater P/ AI when P4 was &lt; 0.43 ng/mL. Fewer (P &lt; 0.01) HC cows had P4 &lt; 0.43 ng/mL at AI than 2PG (84.0 and 97.0%, respectively). Nonetheless, mean P4 concentrations at AI were less than 0.4 ng/mL for HC and 2PG. Although two doses of conventional PGF (total dose: 50 mg) more effectively reduced P4 to &lt; 0.43 ng/mL by the time of AI than one dose of high-concentration PGF (total dose: 25 mg), P/AI was not different between treatments.

Effect of a Trace Mineral Injection on Performance and Trace Mineral Status of Beef Cows and Calves

The objective was to determine the effects of an injectable trace mineral (TMI; Multimin 90) containing copper (Cu), manganese (Mn), selenium (Se), and zinc (Zn) on trace mineral status and the resulting impacts on reproduction of beef cows and the growth of their calves. Beef cows (n = 200) were assigned to receive TMI or no injection (CON) prior to calving and breeding over two consecutive years. Calves born to cows receiving TMI also received TMI at birth in both years and at 49 ± 1.3 days of age in year 1. The TMI increased (p = 0.01) liver Zn and tended (p = 0.06) to increase liver Cu concentrations. Short-lived effects of TMI on Se were observed. Liver Cu and Zn would have been considered adequate and Se marginal in the CON. Pregnancy due to artificial insemination and overall pregnancy rate did not differ (p ≥ 0.36) between treatments. Use of TMI did not increase calf pre-weaning gain. These data indicate that TMI does not improve the reproductive performance of beef cows with adequate trace mineral status or the pre-weaning performance of their calves.

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, n = 12 × 2 yr) vs. inefficient (HRFI, high-residual-feed intake, n = 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. GPS data were recorded at 7-min intervals in 2016 and 4-min intervals in 2017 and accelerometer data recorded at 25 times/s. Grazing time (GT), resting, walking, bite rate (BR), daily travel distance (DTD), elevation, and slope were analyzed with a mixed model that included fixed effects of RFI group, day, and RFI group × day and cow within treatment as the random effect. Cow BW, BCS, and calf weaning weight were analyzed by analysis of variance with treatment as the main effect. There were no differences (P > 0.10) due to RFI detected for BW, BCS, or calf weaning weights. During periods of mild heat load (MHL), HRFI cows spent more (P < 0.05) time resting during the day at lower elevations (P < 0.05) than LRFI cows. During a 6-d period in spring with only 2 h MHL, HRFI cows grazed 1.7 h/d longer than LRFI cows (P < 0.05); commencing grazing earlier in the morning and extending the grazing bout later. During the summer with > MHL, LRFI cows grazed more than HRFI cows 18% of the time (P < 0.10). The HRFI cows had greater GT than LRFI cows only 3% of the time (P < 0.10) during summer. There was no difference (P > 0.10) in BR between HRFI and LRFI cattle. The DTD tended (P < 0.10) to be greater for LRFI cattle during summer 2017. Over all sample periods, HRFI had greater walking than LRFI 15% of the time and LRFI exceeded HRFI cattle for walking 3% of the time (P < 0.10). The greater walking for HRFI was assumed to be associated with more search grazing. Metabolic heat load on hot summer days for HRFI cattle is presumed to have contributed to differences observed in grazing behavior. These results suggest that lactating cows with low-RFI phenotypes appear to be better adapted to grazing rugged rangelands in late summer during periods of MHL.

Genome-Wide Association Analyses of Fertility Traits in Beef Heifers

The ability of livestock to reproduce efficiently is critical to the sustainability of animal agriculture. Antral follicle count (AFC) and reproductive tract scores (RTS) can be used to estimate fertility in beef heifers, but the genetic mechanisms influencing variation in these measures are not well understood. Two genome-wide association studies (GWAS) were conducted to identify the significant loci associated with these traits. In total, 293 crossbred beef heifers were genotyped on the Bovine GGP 50K chip and genotypes were imputed to 836,121 markers. A GWAS was performed with the AFC phenotype for 217 heifers with a multi-locus mixed model, conducted using the year, age at time of sampling and principal component analysis groupings as the covariates. The RTS GWAS was performed with 289 heifers using an additive correlation/trend test comparing prepubertal to pubertal heifers. The loci on chromosomes 2, 3 and 23 were significant in the AFC GWAS and the loci on chromosomes 2, 8, 10 and 11 were significant in the RTS GWAS. The significant region on chromosome 2 was similar between both analyses. These regions contained genes associated with cell proliferation, transcription, apoptosis and development. This study proposes candidate genes for beef cattle fertility, although future research is needed to elucidate the precise mechanisms.

Pre-synchronization of ovulation timing and delayed fixed-time artificial insemination increases pregnancy rates when sex-sorted semen is used for insemination of heifers

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 F_2α (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.

PSVIII-27 Interactions between the stage of maturity of Eragrostis tef hay and supplemental energy source on forage utilization in beef heifers

This study evaluated the interaction between the stage of maturity of Eragrostis tef (teff) grass and supplemental energy source on ruminal fermentation characteristics and nitrogen (N) utilization. Six ruminally-fistulated beef heifers were used in a 3 × 3 split-plot design (21 d periods). The whole plot factor was stage of maturity of teff hay [early- (EH) or late-heading (LH)], and the subplot factor was supplemental energy source [no supplement (CON), rolled corn grain or beet pulp pellet (BP)] fed at 0.5% of body weight. Feed intake was measured daily. Indwelling pH loggers were used to measure ruminal pH (d 14 to 21) and ruminal fluid was collected from d 19 to 21 to determine fermentation characteristics, as were feces and urine to measure N excretion. Data was analyzed using PROC MIXED in SAS. There was no stage of maturity × supplement interaction for all measurements (P ≥ 0.17). Although dry matter intake (DMI) tended to be greater (P = 0.07) for heifers fed EH than LH hay, it did not differ (P = 0.88) across supplements. Ruminal acetate concentration tended (P = 0.098) to be greater for EH than LH heifers, whereas butyrate, isobutyrate, and isovalerate concentrations were greater (P ≤ 0.045) for BPP than CON heifers. However, the duration and area pH &lt; 6.2 and 5.8 did not differ (P &gt; 0.12) across treatments. Except for microbial N flow, which was greater (P &lt; 0.01) for EH than LH heifers, there was no stage of maturity or supplement effect (P ≥ 0.14) on measures of N utilization. In summary, feeding teff hay harvested at the EH than LH stage of maturity increased DMI and microbial N supply, whereas feeding corn and BP as energy supplements to beef heifers had no effect on ruminal pH.

PSXI-7 Comparison of Range-Based and Irrigated Cow-Calf Systems – Grazing Season Performance

The objectives were to compare 1) cow performance, 2) cow fertility, and 3) calf performance in a range-based (RAN) or irrigated (IRR) system over 4 yr. Crossbred beef cows were assigned by age, BW, BCS (1 - emaciated to 9 - obese) and productivity to IRR or RAN. Cows in IRR (n = 170/yr) grazed irrigated cool season perennial pastures (May–October) then grazed crop residues (October-December). Cows in RAN (n = 160/yr) grazed sagebrush steppe range (May–December). Cows were provided hay and supplement (January-mid-March) to achieve BCS 5 by calving. Cows were artificially inseminated (AI). AI sires were distributed across IRR and RAN. Natural service bulls were introduced 8 to 14 d after AI. Cow BW and BCS were recorded at branding (April), pregnancy diagnosis, and end of grazing (December). Pregnancy was diagnosed at 60, 100, and 120 d after AI. Calves were weighed at birth, July, August and weaning (September). Data were analyzed using mixed models with main effect of system. Year (n = 4) was the experimental unit. Cows from the IRR (n = 674) and RAN (n = 638) had similar (P = 0.13) BW at branding but RAN BCS was 0.4 BCS less (P &lt; 0.05). At end of grazing, IRR cows were 96 kg heavier (P &lt; 0.001) and 1.8 BCS greater (P &lt; 0.001) than RAN cows. System did not affect calf birth weight (P = 0.30); however, IRR calves were 20.7 kg heavier (P &lt; 0.003) than RAN calves at weaning. Pregnancy rate was similar (P = 0.64) for IRR and RAN cows (94.7% and 93.6%, respectively). RAN resulted in reduced calf weights and returns per cow (- $60.50) compared to the IRR. In conclusion, producers using sagebrush steppe range will need to operate at a lower cost per cow than irrigated ranches.

147 Presynchronization and delayed fixed-time artificial insemination increases pregnancy rates with sex-sorted semen in replacement beef heifers

To determine effects of presynchronization and delayed fixed-time artificial insemination (TAI) on pregnancy rates to TAI (PR/AI) with sex-sorted semen, 2,855 Bos taurus beef heifers were enrolled in a completely randomized design. Within location, heifers were randomly assigned to one of eight treatments: 1 and 2), heifers were exposed to the 7-d CO-Synch+CIDR protocol wherein they received gonadotropin-releasing hormone (GnRH) and a CIDR insert on d 0, prostaglandin F2α (PGF) upon CIDR removal on d 7, and were TAI 54 ± 2 h later with conventional (CTRL54-CNV; n = 359) or sex-sorted semen (CTRL54-SEX; n = 356); 3 and 4), same as CTRL54 but were TAI at 72 ± 2 h with conventional (CTRL72-CNV; n = 366) or sex-sorted semen (CTRL72-SEX; n = 360); 5 and 6), same as CTRL54 but also received PGF 7 d prior to initial injection of GnRH (d -7) and were TAI with conventional (PRE54-CNV; n = 355) or sex-sorted semen (PRE54-SEX; n = 353); 7 and 8), same as PRE54 but had TAI delayed to 72 ± 2 h and were inseminated with conventional (PRE72-CNV; n = 351) or sex-sorted semen (PRE72-SEX; n = 355). All heifers received estrus detection patches on d 7, which were evaluated for activation at TAI. Ultrasonography was performed 30–45 d after TAI to determine PR/AI. Estrus expression was greater (P &lt; 0.01) in the CTRL72 heifers compared to CTRL54, PRE54, and PRE72 heifers (73.0 vs 55.4, 43.4, and 65.7%, respectively). Moreover, estrus expression was greater (P &lt; 0.01) in PRE72 heifers compared to CTRL54 and PRE54 heifers. Within treatment pairs, PR/AI were greater (P ≤0.04) when conventional semen was utilized compared to sex-sorted semen. Furthermore, PR/AI were greater (P = 0.02) in PRE72-SEX heifers than CTRL54-SEX heifers (45.8 vs. 37.5%). No difference (P = 0.20) was determined in PR/AI between CTRL54-CNV and PRE72-SEX heifers (50.5 vs. 45.8%). In conclusion, presynchronization in combination with delayed TAI increased estrus expression and PR/AI with sex-sorted semen in replacement beef heifers.

Grazing behavior and production characteristics among cows differing in residual feed intake while grazing late season Idaho rangeland

The objectives were to determine whether cows previously classified during a postweaning test as either low or high residual feed intake (LRFI or HRFI) differed in BW, BCS, and winter grazing activity while consuming poor-quality forage. Thirty Hereford × Angus (LRFI = 16; HRFI = 14) 2-yr-old mid- to late-gestation cows (pregnant with second calf) grazed sagebrush steppe for 78 d beginning 29 September 2015. BW and BCS were collected before and after grazing. Five cows of each RFI classification were fitted with global positioning system (GPS) collars on 16 November 2015 with data collection commencing 3 d later and continuing for 25 d in a 323-ha pasture. The GPS units collected location coordinates every 2 min from which total daily travel distance (DTD) was calculated. Visual counts for bite rate were obtained from collared cows over 8 d. Coordinate data, daily bite rate, BW, and BCS were analyzed as repeated measures using a mixed model, which included RFI group, day, and RFI group × day as fixed effects and cow within RFI group as the random effect. Change in BW and BCS was analyzed by ANOVA with RFI group as the main effect. Cow BCS and BW differed for both day (P < 0.0001) and day × RFI (P < 0.05). Body condition was less (P < 0.05) in LRFI cows at the beginning (5.8 ± 0.13 vs. 6.2 ± 0.14 BCS), but similar (P = 0.67) to HRFI at the end of the study (4.6 ± 0.13 vs. 4.6 ± 0.14). BW among the RFI groups did not differ (P = 0.20) prior to going to range. However, BW-change and BCS-change differed (P < 0.05) between RFI groups. Not only did the LRFI cows lose less BW (-50.0 ± 5.41 kg vs. -66.6 ± 5.78 kg) over the trial, they also were less variable with respect to BW loss. Cows did not differ (P > 0.21) by RFI for DTD or bite rate, but day was significant (P < 0.0001) with cows increasing bite rate as the season of year progressed (55.2 ± 5.63 bites/min for day 4 vs. 84.8 ± 5.32 bites/min for day 21) and increasing DTD as snow storms occurred. Although LRFI cows were leaner than HRFI cows at the commencement of the project, they lost less BW in a late season rangeland environment.

PSXIII-22 Modeling the optimal time point at which to perform timed artificial insemination

Timing of artificial insemination (AI) critically impacts likelihood of pregnancy success. In modern timed AI protocols for cattle, AI is performed at a predetermined time point following estrus synchronization. As a result, there may be significant variation among cows or heifers in estrous status and in timing of insemination relative to estrus onset. Recommendations as to when timed AI should be performed are formulated based on research trials evaluating alternative time points. However, available data are limited, as such trials are costly and require large numbers to detect significant differences. As an alternative approach, a mathematical model was developed to predict the anticipated aggregate pregnancy rate to timed AI based on the hour at which timed AI is performed. Previously published distributions of estrus onset were compiled separately for two long-term progestin-based protocols for beef heifers (MGA-PG and 14-d CIDR-PG). Probability of pregnancy was modeled using a regression equation for fertility based on timing of AI in relation to timing of estrus, with heifers grouped in one hour time blocks. Based on a previously published meta-analysis that compiled pregnancy rates when timed AI was performed prior to onset of estrus, a reduced pregnancy rate was assigned to heifers for which timed AI would be performed prior to anticipated estrus expression. Modeled pregnancy rates based on timing of AI were plotted for each protocol. Additionally, use of a split-time AI versus fixed-time AI approach was modeled, as well as predicted impact of varying intervals between the two time points used for split-time AI. Modeled cumulative estrous response and aggregate pregnancy rates were compared to published data for the MGA-PG and 14-d CIDR-PG protocols. Results suggest a mathematical model may be useful to determine the optimal time point at which to perform timed AI following estrus synchronization.

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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 (LM; n = 24; 408 ± 57 kg) or low-moisture molasses-based tub minerals (TUB; n = 24; 396 ± 64 kg). Each treatment was randomized to two of the four irrigated pastures (~5 ha each) consisting of orchard grass (Dactylis glomerat L.), red clover (Trifolium pretense L.), and smooth brome (Bromus inermis). Individual intake was evaluated over three 7-d periods: d – 7 to 0 (adaptation period; AP), d 1 to 7 (period 1; P1), and d 15 to 22 (period 2; P2) of the experiment. The LM mineral mix contained 28% salt during the AP and more salt was added at the initiation of P1 to prevent excessive mineral intake observed during the AP. The LM mineral mix contained 38% salt during P1 and P2. Daily bunk attendance was greater (P < 0.001) for LM (93%) than TUB (67%) steers for the AP. Whereas there was a treatment × period effect (P < 0.001) on daily bunk attendance across P1 (LM: 92%; TUB: 64%) and P2 (LM: 91%; TUB: 82%). Daily mineral intake (as-fed) was greater (P < 0.001) for LM (568 g) than TUB (283 g) during the AP. For P1 and P2, there were no treatment (P = 0.46) and period (P = 0.77) effects on daily mineral intake (LM, 370 g vs. TUB, 343 g), but LM (3.1 visits) had more (P < 0.001) bunk visits per day than TUB (2.0 visits). During the AP, LM (8.5 min) had a greater (P = 0.04) duration of mineral intake per day than TUB (5.6 min); whereas during P1 and P2, TUB (P1 = 8.6; P2 = 12.8 min) had a greater (P ≤ 0.05) duration of mineral intake per day than LM (P1 = 4.9; P2 = 5.7 min). In conclusion, mineral delivery method significantly affected bunk attendance, number of bunk visits per day, and time spent consuming mineral. These results provide additional evidence that mineral type and associated feeding behaviors contribute to the significant variation observed in daily mineral intake in grazing cattle.

Effects of maturity at harvest on the nutritive value and ruminal digestion of Eragrostis tef (cv. Moxie) when fed to beef cattle

Teff (Eragrostis tef cv. Moxie), a warm-season annual grass, could be an excellent forage for beef cattle. However, there is limited information on its nutritive value to cattle when harvested at different stages of maturity. Thus, the objective of this research was to determine the effect of feeding teff hay harvested at the boot (BT), early-heading (EH), or late-heading (LH) stages of maturity on nutrient intake, ruminal fermentation characteristics, omasal nutrient flow, and N utilization in beef cattle. Six ruminally cannulated beef heifers (mean initial BW ± SD, 476 ± 32.6) were used in a replicated 3 × 3 Latin square design with 28-d periods (18 d for adaptation and 10 d for measurements). Dry matter intake was measured daily. Indwelling pH loggers were used to measure ruminal pH from days 21 to 28. Ruminal fluid and omasal digesta were collected from days 26 to 28 to determine fermentation characteristics and omasal nutrient flow. Fecal and urine samples to quantify N excretion were also collected (days 26 to 28). Blood samples for plasma urea-N (PUN) determination were collected 3 h post-feeding on day 28. There were no changes (P > 0.28) in the ADF or NDF content of teff with advancing maturity, but indigestible NDF increased (P < 0.01) with increasing maturity. Maturity had no effect (P ≥ 0.14) on DMI, and ruminal total short-chain fatty acid (SCFA) concentration, pH, digestibility, and outflow of DM, OM, NDF, ADF, and CP. However, the CP content of BT hay was greater (P < 0.01) than for EH and LH hay (18.1, 14.1, and 11.5%, respectively, DM basis), and this resulted in the higher CP intake (P < 0.01) for heifers fed the BT than the EH and LH hay. Consequently, ruminal ammonia-N (NH3-N) concentration was greater (P < 0.01) for heifers fed BT than EH and LH hay, thereby possibly explaining the tendency for a decrease (P = 0.08) in PUN concentration, and a decrease (P < 0.01) in the excretion of total N, urine N, and urea-N (UUN) with advancing maturity. However, fecal N excretion (g/d) did not differ (P = 0.76). In conclusion, despite a decrease in CP intake and ruminal NH3-N concentration, feeding beef heifers EH and LH compared to BT teff hay did not compromise ruminal digestion and outflow of DM, OM, NDF, ADF, and CP, and microbial protein synthesis. Advancing maturity in teff hay also resulted in a decrease in the excretion of total N and urine N and UUN when fed to cattle.

Flunixin meglumine improves pregnancy rate in embryo recipient beef cows with an excitable temperament

Objectives were to determine effects of: 1) handling temperament and administration of flunixin meglumine, an inhibitor of prostaglandin F2a (PGF2a) synthesis, given at the time of embryo transfer, on pregnancy rates in beef cattle embryo transfer recipients; 2) handling temperament and flunixin meglumine on peripheral concentrations of progesterone, cortisol, substance-P, prostaglandin F metabolites (PGFM, (13,14-dihydro-15-keto-PGF2a) and isoprostane 8-epi PGF2a; and 3) flunixin meglumine treatment on proportion of non-pregnant recipient cows returning to estrus within an expected interval. Angus cross beef cows (n = 710) at 7 locations were assigned a body condition score (BCS: 1, emaciated; 9, obese) and a temperament score [0, calm, slow chute exit; walk (n = 352), 1, excited, fast chute exit; jump, trot or run (n = 358)] and were synchronized with Select-Synch with a controlled internal drug release (CIDR) protocol. Estrus detection aids were applied at CIDR removal and cows were observed thrice daily for estrus until 72 h. Recipient cows that expressed estrus and had a corpus luteum received a frozen-thawed embryo on Day 7 after estrus. At the time of transfer, recipient cows were randomly allocated to receive 10 mL of flunixin meglumine im, immediately after transfer (n = 365) or served as an untreated control (n = 345). In a subset of cows (n = 80), ovarian ultrasonography was performed on the day of embryo transfer to determine corpus luteum volume and blood samples were collected twice, at the time of embryo transfer and 7 d later. All cows received estrus detection aids again on Day 14 (7 d after embryo transfer) and were observed for estrus twice daily until Day 24. Accounting for treatment (P > 0.1), embryo transfer difficulty score (P < 0.1), temperament by treatment interaction (P < 0.05), recipient cows with calm temperament had a higher pregnancy rate compared to those with an excited temperament [59.4 (209/352) vs 51.7% (185/358)]. The pregnancy rate for excitable cows without flunixin meglumine was lower (46.3% 81/175) compared to excitable cows that did received flunixin meglumine [56.8% (104/183)], and calm cows that did [59.3% (108/182)] or did not [59.4% (104/170)] receive flunixin meglumine. Proportions of non-pregnant recipient cows returning to estrus on Days 18-24 were not different between flunixin meglumine and control groups, 87.6% (134/153) and 84.0% (137/163), respectively (P > 0.1). At the time of embryo transfer and 7 d later, there were moderate to strong correlations among circulating concentrations of progesterone, cortisol, substance-P, PGFM and isoprostane 8-epi PGF2a. Among excitable cows, progesterone concentrations were lower and cortisol, substance-P, PGFM and isoprostane 8-epi PGF2a concentrations were greater for cows in the control group compared to cows that received flunixin meglumine. In conclusion, administration of flunixin meglumine improved pregnancy rates in excitable recipient cows following embryo transfer without affecting the proportion of non-pregnant cows returning to estrus.

Effective use of SexedULTRA™ sex-sorted semen for timed artificial insemination of beef heifers

An experiment was designed to evaluate the relative fertility of SexedULTRA^TM sex-sorted semen compared to conventional, non-sex-sorted semen when used among beef heifers in conjunction with split-time AI following the 14-d CIDR-PG protocol. Units of conventional semen were generated with 25.0 × 10⁶ live cells per 0.5 ml straw prior to freezing, and units of sex-sorted semen were generated using the SexedULTRA^TM Genesis III sorting technology with 4.0 × 10⁶ live cells per 0.25 ml straw prior to freezing. Sex-sorted units were sorted to contain X chromosome-bearing sperm cells at an accuracy level of >90%. Estrus was synchronized in 851 heifers at four locations using the 14-d CIDR-PG protocol: controlled internal drug release (CIDR) insert (1.38 g progesterone) on Day 0, CIDR removal on Day 14, and administration of prostaglandin F_2α (PG; 25 mg im) on Day 30. Estrus detection aids were applied at PG on Day 30 to evaluate estrous response rate, and split-time AI was performed based on estrous response. At 66 h after PG (Day 33), heifers having expressed estrus received timed AI. Heifers failing to express estrus by 66 h received timed AI 24 h later (90 h after PGF_2α on Day 34). Heifers failing to express estrus by 90 h were administered gonadotropin-releasing hormone (GnRH; 100 μg im) concurrent with AI. Heifers were preassigned to treatment (insemination with either conventional or SexedULTRA^TM sex-sorted semen), and treatments were balanced within each location based on source, reproductive tract score, and weight. Heifers were exposed for natural service beginning 14 d after AI for the remainder of a 60 d breeding season. Pregnancy rates to AI across locations tended to be higher (P = 0.09) for heifers inseminated with conventional semen (60%; 257/429) compared to sex-sorted semen (52%; 218/422). Higher pregnancy rates to AI (P < 0.0001) were obtained among heifers that expressed estrus prior to AI than among heifers that failed to express estrus prior to AI at 90 h. Total pregnancy rates at the end of the 60 d breeding season did not differ between heifers that received sex-sorted semen at AI (89%; 376/422) and heifers that received conventional semen at AI (89%; 382/429). In summary, the pregnancy rates observed suggest that SexedULTRA^TM sex-sorted semen can be used effectively for timed AI of beef heifers when split-time AI is performed following the 14-d CIDR-PG protocol.

Relationships of feeding behaviors with average daily gain, dry matter intake, and residual feed intake in Red Angus-sired cattle

Feeding behavior has the potential to enhance prediction of feed intake and to improve understanding of the relationships between behavior, DMI, ADG, and residual feed intake (RFI) in beef cattle. Two cohorts, born in 2009 and 2010, the progeny of Red Angus bulls (n = 58 heifers and n = 53 steers), were evaluated during the growing phase, and the latter group of steers was also evaluated during the finishing phase. All behavior analyses were based on 7 feeding behavior traits (bunk visit frequency, bunk visit duration [BVDUR], feed bout frequency, feed bout duration, meal frequency, meal duration, and average meal intake) and their relationships with ADG, DMI, and RFI. During the growing phase, feeding duration traits were most indicative of DMI with positive correlations between BVDUR and DMI for cohort 1 steers, growing phase (n = 28, r = 0.52, P = 0.00); cohort 2 steers, growing phase (n = 25, r = 0.44, P = 0.01); and cohort 2 heifers, growing phase (n = 29, r = 0.28 P = 0.05). There were similar trends toward correlation of BVDUR and RFI for both steer groups and cohort 1 heifers, growing phase (C1HG; n = 29; r = 0.27, P = 0.06; r = 0.30, P = 0.07; and r = 0.26, P = 0.08, respectively). Feed bout frequency was correlated with ADG in C1HG and in cohort 2 steers, finishing phase (r = -0.31, P = 0.04, and r = 0.43, P = 0.01, respectively). Feed bout duration was correlated with ADG in heifer groups (r = 0.29 and r = 0.28, P = 0.05 for both groups) and DMI for all growing phase animals (r = 0.29 to 0.55, P ≤ 0.05 for all groups). Evaluation of growing vs. finishing phase steer groups suggests that all behaviors, RFI, and DMI, but not ADG, are correlated through the growing and finishing phases (P ≤ 0.01 for all variables excluding ADG), implying that feeding behaviors determined during the growing phase are strong predictors of DMI in either life stage. Sire maintenance energy EPD effects (measured as high or low groups) on progeny feeding behaviors revealed a difference in meal duration with a tendency to differ in average meal intake (P = 0.01 and P = 0.07, respectively). Feeding behavior duration traits may be useful predictors of DMI in Red Angus cattle.

Calm temperament improves reproductive performance of beef cows

Profitability of a beef operation is determined by the proportion of cows attaining pregnancy early in the breeding season and those that are pregnant at the end of breeding season. Many factors, including temperament, contribute to those reproductive parameters. The objective of this study was to evaluate effects of temperament on reproductive performance of beef cows. In Experiment 1, Angus and Angus-cross beef cows (n = 1546) from eight locations were assigned a body condition score (BCS; 1 = emaciated; 9 = obese) and chute exit and gait score (1 = slow exit, walk; calm temperament; 2 = jump, trot or run; excitable temperament). Cows were grouped with bulls (1 : 25 to 1 : 30; with satisfactory breeding potential and free of venereal disease) for an 85-day breeding season. Pregnancy status and stage of gestation were determined (transrectal palpation) 35 days after the end of the breeding season. Controlling for BCS (p < 0.01) and handling facility (p < 0.0001) and handling facility by temperament score interaction (p < 0.001), breeding season pregnancy rate was lower in excited versus calm cows [88.6% (798/901) vs 94.1% (607/645); p < 0.001]. Cows with an excitable temperament took 24 more days to become pregnant compared to calm cows (median days to pregnancy, 35 vs 59 days; p < 0.0001). In Experiment 2, Angus and Angus-cross beef cows (n = 1407) from 8 locations were assigned scores for body condition and chute exit and gait (as described in Experiment 1) and assigned to bulls (breeding sound and free of venereal disease; 1 : 25 to 1 : 30) for 85 days. Pregnancy status was determined by transrectal palpation at 2 and 6 months after the onset of the breeding season. Controlling for BCS (p < 0.05), pregnancy loss was higher in excited versus calm cows [5.5% (36/651) vs 3.2% (20/623), p < 0.0001]. In conclusion, beef cows with an excitable temperament had significantly lower reproductive performance than calmer cows. The modified two-point chute exit-gait scoring method was repeatable and identified cattle with an excitable temperament.

Relationships of feeding behaviors with efficiency in RFI-divergent Japanese Black cattle

New approaches to limit expenses associated with input, without compromising profit, are needed in the beef industry. Residual feed intake (RFI) is an efficiency trait that measures variation in feed intake beyond maintenance, growth, and body composition. The addition of feeding behavior analysis to standard RFI tests may provide an approach to more readily identify feed-efficient cattle. The current study analyzes 7 feeding behaviors (BVFREQ: bunk visit frequency, BVDUR: bunk visit duration, FBFREQ: feed bout frequency, FBDUR: feed bout duration, MFREQ: meal frequency, MDUR: meal duration, and AMINT: average meal intake) and their relationships with RFI, ADG, and DMI in Japanese Black (Wagyu) cattle. Three cohorts of yearling Wagyu animals were studied using a standard 70-d RFI test, and data from divergent ( ± 0.5 SD from population RFI mean) subsets of animals were analyzed for feeding behaviors [n = 58, bulls on high-concentrate diet (C1); n = 36, bulls on a lower-concentrate diet (C2); n = 34, heifers on a lower-concentrate diet (C3)]. The following behaviors were correlated with ADG: BVFREQ (r = 0.32, P = 0.01; C1 bulls), BVDUR (r = 0.42, P = 0.01, C2 bulls), FBFREQ (r = 0.37, P < 0.01; C1 bulls), FBDUR (r = 0.46, P < 0.01, C1 bulls), and MFREQ (r = 0.42, P < 0.01, C2 bulls). Behaviors were trending or significantly correlated with DMI for all cases except for MFREQ for C3 and AMINT for C2. Residual feed intake was positively correlated with MDUR across all cohorts (r = 0.31, P = 0.02; r = 0.38, P = 0.02; r = 0.54, P ≥ 0.01, respectively). For C2 bulls and C3 heifers, RFI was positively correlated with behavior frequency categories (BVFREQ; r = 0.44, P = 0.01; r = 0.60, P ≤ 0.01, respectively, and FBFREQ r = 0.46, P ≤ 0.01; r = 0.60, P ≤ 0.01, respectively). Bunk visit frequency and FBFREQ were highly correlated with RFI status (high or low) in C2 bulls and C3 heifers. Behavior duration categories (BVDUR, FBDUR, and MDUR) were most correlated with efficiency status in C1 bulls. However, behavior frequency categories (BVFREQ and FBFREQ), as well as MDUR, were most correlated with efficiency status in C2 bulls and C3 heifers. Inclusion of meal duration measurements when evaluating RFI provides an additional tool in understanding the drivers of variation in this important trait in Wagyu cattle. The present study provides new insights into feed intake patterns of a beef breed for which there are few reports of feeding behavior.

Prior infections are associated with increased mortality from subsequent blood-stream infections among patients with hematological malignancies

Many patients who are evaluated and treated for sepsis have histories of recent infections. The prognostic implications of surviving an infectious process are not well understood. We undertook this study to determine the clinical impact of prior infections among patients with hematological malignancies, a population at high risk for developing and dying from sepsis. The medical records of 203 patients with hematological malignancies and blood-stream infections admitted over a 3-year period to an urban teaching hospital were retrospectively reviewed. The 30-day mortality after blood-stream infection in these high-risk patients was 24 %. There were 46 patients (23 %) who had inpatient infections in the 90 days prior to the index blood-stream infection. History of recent infection portended worse prognosis from blood-stream infection under multivariable analysis [odds ratio (OR) 2.60, p = 0.04, 95 % confidence interval (CI) 1.04-6.47]. There were 86 patients (42 %) who had subsequent infections in the first 90 days after the index blood-stream infection. Patients with subsequent infections had greater mortality during days 91-365 than patients without subsequent infections [hazard ratio (HR) 1.97, p = 0.02, 95 % CI 1.13-3.44]. Recent infections prognosticate worse outcomes from subsequent blood-stream infections for this high-risk population. Further research into the clinical and biochemical reasons for this observation may lead to targets for intervention, and, ultimately, improvements in long-term mortality from sepsis.

Effect of reproductive tract scoring on reproductive efficiency in beef heifers bred by timed insemination and natural service versus only natural service

The objective was to determine the effects of reproductive tract score (RTS) on reproductive performance in beef heifers bred by timed artificial insemination followed by natural service (AI-NS) or by natural service only (NSO). Angus cross beef heifers (n = 2660) in the AI-NS group were artificially inseminated at a fixed time (5- or 7-day CO-Synch + controlled internal drug release protocol) once, then exposed to bulls 2 weeks later (bull-to-heifer ratio = 1:40-1:50) for the reminder of the 85-day breeding season. Angus cross beef heifers (n = 1381) in NSO group were submitted to bulls (bull-to-heifer ratio = 1:20-1:25) for the entire 85-day breeding season. Heifers were reproductive tract scored from 1 (prepubertal) to 5 (cyclic) 4 weeks before, and were body condition scored (BCS) from 1 (emaciated) to 9 (obese) at the beginning of breeding season. Pregnancy diagnosis was performed 70 days after AI for AI-NS group and 2 months after the end of breeding season for both groups. Heifers in both groups were well managed and of similar age (14.9 ± 0.4 [AI-NS] and 14.7 ± 0.8 [NSO] months). Pregnancy rates (PRs) and number of days to become pregnant were calculated using PROC GLIMMIX and PROC LIFETEST procedures of SAS. Adjusting for BCS (P = 0.07), expressed estrus (P < 0.05), year (P < 0.05), and BCS by year interaction (P < 0.05), the AI-PR was greater for heifers in AI-NS group with higher RTS (P < 0.0001; 40.7%, 48.3%, 57.6%, and 64.6% for RTS of 2 or less, 3, 4, and 5, respectively). Controlling for BCS (P < 0.05), year (P < 0.05) and the breeding season pregnancy rates (BS-PRs) were greater for heifers in the AI-NS group with higher RTS (P < 0.01; 81.2%, 86.5%, 90.4%, and 95.2% for RTS of 2 or less, 3, 4, and 5, respectively). Similarly, adjusting for BCS, year (P < 0.05), the BS-PR was greater for heifers in NSO group with higher RTS (P < 0.01; 79.7%, 84.3%, 88.4%, and 90.2% for RTS of 2 or less, 3, 4, and 5, respectively). Heifers with higher RTS in both groups became pregnant earlier in the breeding season compared with heifers with lower RTS (log-rank statistics: P < 0.0001). Heifers in the AI-NS group become pregnant at a faster rate compared with those in the NSO group (P < 0.01). The BS-PR for heifers with RTS 5 was different between AI-NS and NSO groups (P < 0.0001). In conclusion, the RTS influenced both the number of beef heifers that became pregnant during the breeding season and the time at which they become pregnant. Furthermore, irrespective of RTS, heifers bred by NSO required more time to become pregnant than their counterparts in herds that used timed AI. The application of RTS system is reliant on the use of synchronization protocol. The application of RTS for selection may plausibly remove precocious females with lower RTS. On the contrary, application of RTS would help select heifers that will become pregnant earlier in breeding season.

Nutritional development and the target weight debate

Postnatal nutrition has immediate and long-lasting effects on beef heifer reproductive efficiency, longevity, and productivity. This article reviews the effects of nutrients and nutritional management on reproduction in developing heifers. In addition, the current debate on the preferred target weight for heifers at breeding is discussed.

Relationships among performance, residual feed intake, and product quality of progeny from Red Angus sires divergent for maintenance energy EPD

Energy expenditure is a physiological process that may be closely associated with residual feed intake (RFI). The maintenance energy (ME(M)) EPD was developed by the Red Angus Association of America (RAAA) and is used as an indicator of energy expenditure. The objectives of this study were to evaluate and quantify the following relationships using progeny of Red Angus (RA) sires divergent for ME(M) EPD: 1) postweaning RFI and finishing phase feed efficiency (FE), 2) postweaning RFI and end-product quality, and 3) postweaning RFI and sire ME(M) EPD. A total of 12 RA sires divergent for ME(M) EPD were chosen using the RAAA-generated ME(M) EPD values and were partitioned into 2 groups: high ME(M) EPD (≥4 Mcal/mo) and low ME(M) EPD (<4 Mcal/mo), based on the breed average of 4 Mcal/mo. Commercial crossbred cows were inseminated to produce 3 cohorts of progeny, which were tested for postweaning RFI (cohorts 1, 2, and 3) and finishing phase FE (cohorts 1 and 3). Results indicate that postweaning RFI and finishing phase FE of steer progeny tended to be positively correlated (r = 0.38; P = 0.06) in cohort 1 and were positively correlated (r = 0.50; P = 0.001) in cohort 3. In addition, postweaning RFI was not phenotypically correlated (P > 0.05) with any carcass traits or end-product quality measurements. Sire ME(M) EPD was phenotypically correlated (P < 0.05) with carcass traits in cohort 1 (HCW, LM area, KPH, fat thickness, and yield grade) and cohort 2 (KPH and fat thickness). Since variation in measured LM area was not explained by the genetic potential of rib eye area EPD, and therefore, the observed correlation between sire ME(M) EPD and measured LM area may suggest an association between ME(M) EPD and LM area. A correlation (r = 0.24; P = 0.02) was observed between postweaning RFI and ultrasound intramuscular fat percentage in cohort 2 but was not detected in cohorts 1 or 3. In addition, no phenotypic relationship was observed (P > 0.05) between progeny postweaning RFI and sire ME(M) EPD. Therefore, results suggest 1) RFI measured during the postweaning growth phase is indicative of FE status in the finishing phase, 2) neither RFI nor sire ME(M) EPD negatively affected carcass or end-product quality, and 3) RFI and sire ME(M) EPD are not phenotypically associated.

Artificial insemination at 56 h after intravaginal progesterone device removal improved AI pregnancy rate in beef heifers synchronized with five-day CO-Synch + controlled internal drug release (CIDR) protocol

The objective was to determine whether timed artificial insemination (TAI) 56 h after removal of a Controlled Internal Drug Release (CIDR, 1.38 g of progesterone) insert would improve AI pregnancy rate in beef heifers compared to TAI 72 h after CIDR insert removal in a 5-days CO-Synch + CIDR protocol. Angus cross beef heifers (n = 1098) at nine locations [WA (5 locations; n = 634), ID (2 locations; n = 211), VA (one location; n = 193) and WY (one location; n = 60)] were included in this study. All heifers were given a body condition score (BCS; 1-emaciated; 9-obese), and received a CIDR insert and 100 μg of gonadorelin hydrochloride (GnRH) on Day 0. The CIDR insert was removed and two doses of 25 mg of dinoprost (PGF(2α)) were given, first dose at CIDR insert removal and second dose 6 h later, on Day 5. A subset of heifers (n = 629) received an estrus detector aid at CIDR removal. After CIDR removal, heifers were observed thrice daily for estrus and estrus detector aid status until they were inseminated. Within farm, heifers were randomly allocated to two groups and were inseminated either at 56 h (n = 554) or at 72 h (n = 544) after CIDR removal. All heifers were given 100 μg of GnRH at AI. Insemination 56 h after CIDR insert removal improved AI pregnancy rate compared to insemination 72 h (66.2 vs. 55.9%; P < 0.001; 1 - β = 0.94). Locations, BCS categories (≤ 6 vs. > 6) and location by treatment and BCS by treatment interactions did not influence AI pregnancy rate (P > 0.1). The AI pregnancy rates for heifers with BCS ≤ 6 and > 6 were 61.8 and 60.1%, respectively (P > 0.1). The AI pregnancy rates among locations varied from 54.9 to 69.2% (P > 0.1). The AI pregnancy rate for heifers observed in estrus at or before AI was not different compared to heifers not observed in estrus [(65.4% (302/462) vs. 52.7% (88/167); P > 0.05)]. In conclusion, heifers inseminated 56 h after CIDR insert removal in a 5-days CO-Synch + CIDR protocol had, on average, 10.3% higher AI pregnancy rate compared to heifers inseminated 72 h after CIDR insert removal.

Multi-state Beef Reproduction Task Force provides science-based recommendations for the application of reproductive technologies

Since its formation, the Beef Reproduction Task Force (BRTF) has worked to enhance productivity and profitability of US beef herds by integrating research and extension efforts with the intent of more effectively transferring the use of reproductive technologies to the field. A key early step was to coordinate efforts in identifying effective breeding management protocols for beef cattle and to clarify their associated acronyms. A short list of recommended protocols and their acronyms for synchronization of estrus and ovulation in beef cattle was developed based on results from peer-reviewed, published research and a comprehensive review of data collected from the field. The list of recommended protocols was developed by the BRTF in cooperation with veterinarians and cattle AI industries. These protocols and their acronyms are presented uniformly in all of the major AI sire directories and are available online at http://www.beefrepro.info. Protocol updates are made annually to incorporate the most recent research findings related to estrous cycle control in beef cattle. The Estrus Synchronization Planner, a software program developed in cooperation with the Iowa Beef Center, now reflects these same recommendations. Beginning in 2002, the BRTF hosted and presented 11 educational workshops to more than 1,900 attendees in key cow-calf states. These Applied Reproductive Strategies in Beef Cattle workshops targeted beef producers, AI industry personnel, veterinarians, allied industry representatives, and academicians. A national media sponsor provided online coverage of the last 3 workshops at http://www.appliedreprostrategies.com. A postmeeting evaluation, developed to assess application of information from 2 recent workshops, was returned by 55% of those contacted (n = 150). Attendees averaged 16 (± 13.4 SD) yr of AI experience, and 80% of respondents represented more than 100 cows. Respondents were asked to estimate the value of AI-sired calves compared with natural-service-sired calves to their operation on a per-animal-marketed basis, and 17 and 31% responded $50 to $100 per animal and more than $100 per animal, respectively. As a result of what was learned at these conferences, 78% of respondents were better able to troubleshoot management-related issues, 60% made alterations to a protocol they had been using, and 35% of the respondents indicated they changed to a different estrus synchronization protocol.

Effect of feeding level on serum IGF1 response to GH injection

This study was conducted to further understand the mechanism by which nutrition modulates GH-induced changes in serum IGF1 concentration in cattle. Cows were fed hay only or corn-based concentrates in addition to hay for 8 weeks. At week 8, serum concentrations of IGF1, IGF-binding protein 3 (IGFBP3), and acid-labile subunit (ALS) as well as their mRNA levels in liver were determined immediately before and 7 days after an injection of GH formulated for sustained release. GH injection caused greater increases in both serum IGF1 concentration and liver IGF1 mRNA expression in the cows fed concentrates than in those fed hay. In the cows fed concentrates, the magnitude of the GH-induced increase in serum IGF1 concentration was, however, much greater than that in liver IGF1 mRNA expression. This difference was not due to GH-induced IGF1 mRNA being translated more efficiently. GH injection also induced greater increases in serum IGFBP3 and ALS concentrations in the cows fed concentrates than fed hay. The injection, however, did not induce a greater increase in IGFBP3 or ALS mRNA in the cows fed concentrates than fed hay. These data and the fact that the ternary complex of IGF1/IGFBP3/ALS stabilizes each of the components in the blood suggest that in cows, increased nutrition enhances serum IGF1 response to GH not only by increasing IGF1 mRNA response to GH in the liver, but also by elevating IGFBP3 and ALS concentrations in the blood.

Fixed-time AI pregnancy rate following insemination with frozen-thawed or fresh-extended semen in progesterone supplemented CO-Synch protocol in beef cows

The objective of this study was to compare fixed-time AI pregnancy rate in Angus crossbred beef cows inseminated with frozen-thawed or fresh-extended semen. Two ejaculates from each of two Angus bulls were collected by artificial vagina and pooled for each bull. The pooled semen from each bull was divided into two aliquots; Aliquot 1 was extended using Caprogen (LIC, Hamilton, New Zealand) to a concentration of 3 x 10(6)sperm/straw and Aliquot 2 was extended using egg-yolk-glycerol extender to a concentration of 20 x 10(6)sperm/straw. Semen extended with Caprogen was maintained at ambient temperature and semen extended with egg-yolk-glycerol extender was frozen and maintained at -196 degrees C until insemination. In each of two breeding seasons (Fall 2007 and Spring 2008), Angus-crossbeef cows (N=1455) at 12 locations were randomly assigned within location to semen type [Fresh (N=736) vs. Frozen (N=719)] and sire [1 (N=731) vs. 2 (N=724)]. All cows were synchronized with 100 microg of GnRH im and a progesterone Controlled Internal Drug Release insert (CIDR) on Day 0, and on Day 7, 25mg of PGF2(alpha) im and CIDR removal. All cows received 100 microg of GnRH im and were inseminated at a fixed-time on Day 10, 66 h after CIDR removal. Timed-AI pregnancy rates were influenced by season (P<0.05), cows detected in estrus prior to and at AI (P<0.001), and dam age (P<0.01). Pregnancy rates were not affected by semen type (Fresh=51.5% vs. Frozen=50.4%; P=0.66) and there were no significant interactions of semen type by estrus expression, semen type by sire, or semen type by season (P>0.1). In conclusion, commercial beef cows inseminated with fresh-extended semen (3 x 10(6)sperm/straw) yielded comparable pregnancy rates to conventional frozen-thawed semen in a progesterone supplemented, CO-Synch fixed-time AI synchronization protocol and may provide an alternate to frozen semen for more efficient utilization of superior genetics.

Increased degradation of insulin-like growth factor-I in serum from feed-deprived steers

Severe feed restriction decreases serum insulin-like growth factor I (IGF-I) concentration in animals, and this decrease is thought to be due to reduced IGF-I production in the liver. The objective of this study was to determine whether feed deprivation also increases degradation of serum IGF-I and serum levels of IGF binding protein 3 (IGFBP-3) and acid-labile subunit (ALS), which inhibit IGF-I degradation and increase IGF-I retention in the blood by forming a ternary complex with IGF-I, in cattle. Five steers had free access to pasture, and another five were deprived of feed for 60 h. Serum concentration of IGF-I and liver abundance of IGF-I mRNA at the end of the 60-h period were 50% and 80% lower, respectively, in feed-deprived steers than in fed steers. Less (125)I-labeled IGF-I remained intact after a 45-h incubation in sera of feed-deprived steers than in sera of fed steers, suggesting that serum IGF-I is more quickly degraded in feed-deprived animals. Serum levels of IGFBP-3 and ALS were decreased by 40% and 30%, respectively, in feed-deprived steers compared with fed steers. These decreases were associated with more than 50% reductions in IGFBP-3 and ALS mRNA in the liver, the major source of serum IGFBP-3 and ALS. Taken together, these results suggest that feed deprivation reduces serum concentration of IGF-I in cattle not only by decreasing IGF-I gene expression in the liver, but also by increasing IGF-I degradation and reducing IGF-I retention in the blood through decreasing IGFBP-3 and ALS production in the liver.

Sire effect on the pregnancy outcome in beef cows synchronized with progesterone based Ovsynch and CO-Synch protocols

The objective was to determine the sire effect on the pregnancy outcome in beef cows in which stage of estrus was synchronized with progesterone based fixed-time artificial insemination (AI) protocols. Three Angus sires with more than 300 breedings were evaluated for differences in pregnancy outcome from 1868 inseminations. Angus cross beef cows (N=1868) were synchronized with Ovsynch-CIDR or CO-Synch-CIDR protocols for fixed-time AI. Cows in both groups that showed estrus on day 9 before 1500 h were designated to Selectsynch-CIDR group and were inseminated according to AM-PM rule. Results indicated that Sire 2 had lower fixed-time AI pregnancy rate compared to Sire 3 (48.1% versus 58.7%; P=0.01). Significant sirexsynchronization program and sirexlocation interactions were observed for fixed-time AI (P<0.05). Sire 2 had a lesser fixed-time AI pregnancy in both Ovsynch-CIDR and CO-Synch-CIDR groups compared to Sire 3. In two of four locations, Sire 2 had a lesser fixed-time pregnancy rate compared to Sire 3. No sire differences were observed in AI pregnancy for cows in Selectsynch-CIDR group. In conclusion, evidence in this study suggest that there are differences in sire fertility when they were used in fixed-time AI protocols, possibly due to the sire differences in sperm capacitation process. Further studies are needed to investigate association of the sire differences in fixed-time AI protocols with sire differences in the sperm capacitation process.

A phase II trial of EMD72000 (matuzumab), a humanized anti-EGFR monoclonal antibody, in patients with platinum-resistant ovarian and primary peritoneal malignancies

OBJECTIVE

The primary objective of this study was to determine the rate of response to matuzumab in patients with recurrent, EGFR-positive ovarian, or primary peritoneal cancer. Secondary end points included safety and tolerability, time to tumor progression, duration of response, and overall survival.

METHODS

A multi-institutional single arm phase II trial.

RESULTS

Of 75 women screened for the study, 37 were enrolled and treated. Median age of the treated patient population was 58 years, and most patients had more than four prior lines of chemotherapy. Therapy was well tolerated, the most common toxicities being a constellation of skin toxicities, including rash, acne, dry skin, and paronychia, as well as headache, fatigue, and diarrhea. Serious adverse events were very rare but included a single episode of pancreatitis that may have been drug related. All patients completed therapy, receiving 1 to 30 infusions of matuzumab. There were no formal responses (RR=0%, 95% CI: 0-9.5%), although 7 patients (21%) were on therapy for more than 3 months with stable disease.

CONCLUSIONS

Matuzumab at the dose and schedule selected is well tolerated. In this population of very heavily pretreated patients with epithelial ovarian and primary peritoneal malignancies, there was no evidence of significant clinical activity when matuzumab was administered as monotherapy.

Effect of timing of prostaglandin administration, controlled internal drug release removal and gonadotropin releasing hormone administration on pregnancy rate in fixed-time AI protocols in crossbred Angus cows

Two experiments were conducted to investigate the effects of timing of prostaglandin F2(alpha) (PGF2(alpha)) administration, controlled internal drug release device (CIDR) removal and second gonodotropin releasing hormone (GnRH) administration on the pregnancy outcome in CIDR-based synchronization protocols. In Experiment 1, suckled Angus crossbred beef cows (n = 580) were given 100 microg of GnRH+a CIDR on Day 0. Cows in Group 1 (modified Ovsynch-P) received 25 mg of dinoprost (PGF2(alpha)) and CIDR device removal on Day 8 (AM), 100 microg of GnRH 36 h later on Day 9 (p.m.), and fixed-time AI (FTAI) 16 h later on Day 10 (47.5+/-1.1 h after PGF2(alpha)). Cows in Group 2 (Ovsynch-P) received 25mg of PGF2(alpha) and CIDR device removal on Day 7 (p.m.), 100 microg of GnRH 48 h later on Day 9 and FTAI 16 h later on Day 10 (66.6+/-1.2 h after PGF2(alpha)). Pregnancy rates were 56.5% (170/301) for Group 1 and 55.6% (155/279) for Group 2, respectively (P = 0.47). In Experiment 2, beef cows (n=734) were synchronized with 100 microg of GnRH+CIDR on Day 0, 25 mg of PGF2(alpha) and CIDR device removal on Day 7 and either 100 microg of GnRH 48 h later on Day 9 (Ovsynch-P) and FTAI 16 h later on Day 10 (64.9+/-3.3 h from PGF2(alpha)) or 100 microg of GnRH on Day 10 (CO-Synch-P) at the time of AI (63.2+/-4.2 h from PGF2(alpha)). Pregnancy rates were 48.8% (180/369) for Ovsynch-P and 44.7% (163/365) for CO-synch-P groups, respectively (P = 0.11). In both experiments, there was a locationxtreatment interaction (P<0.05); pregnancy rates between locations were different (P < 0.05) in the Ovsynch-P group. In conclusion, in a CIDR-based Ovsynch synchronization protocol, delaying administration of prostaglandin and CIDR removal by 12 h, or timing of the second GnRH by 16 h, did not affect pregnancy rates to FTAI. Therefore, there may be an opportunity to make changes in synchronization protocols with out adversely affecting FTAI pregnancy rates.

Effects of feeding supplemental fat to beef cows on cold tolerance in newborn calves

Our objectives were to examine the effects of added fat in late-gestation cow diets on neonatal response to cold. In Exp. 1, pregnant fall-calving heifers received control (n = 5), safflower seed (n = 5), or whole cottonseed (n = 5) diets. The hay-based, isonitrogenous, and isocaloric diets, fed for 47 d prepartum, contained 1.5, 4.0, and 5.0% fat for control, safflower, and whole cottonseed diets, respectively. At calving, calf BW and vigor score, as well as fat, lactose, and IgG in colostrum were not affected (P > 0.30) by diet. Heifers fed the safflower diet tended to have greater colostral solids (P < 0.10) than heifers fed the control or whole cottonseed diets. At 6.5 h of age, calves were placed in a 5 degrees C cold room for 90 min. Calf vigor, shivering, body temperature, and blood samples were taken every 15 min. During cold stress, calf body temperature decreased 0.7 degrees C (P < 0.03). Across all diets, shivering and serum glucose concentrations increased (P < 0.05), whereas calf vigor and cortisol concentrations decreased (P < 0.02) during cold exposure. In Exp. 2, pregnant spring-calving cows (n = 98) received a control (n = 47) or whole cottonseed (n = 51) supplement. Hay-based diets fed for 68 d prepartum contained 2.0 and 5.0% fat for control and whole cottonseed diets, respectively. Calf BW, vigor, shivering, dystocia score, time to stand, time to nurse, serum glucose concentrations, and serum IgG were not affected (P > 0.50) by diet. Between 30 and 180 min, body temperature of calves from dams fed the whole cottonseed supplement decreased (P < 0.05) more than calves from dams fed the control supplement. Serum glucose concentrations in calves were not affected by diet (P > 0.30). Serum cortisol concentrations tended (P < 0.09) to be greater for calves from dams fed whole cottonseed than control calves. When ambient temperature was < 6 degrees C, calves born to dams fed whole cottonseed had greater (P < 0.05) BW, tended (P < 0.1) to stand earlier, and had greater serum IgG concentrations. We conclude that calves from dams fed high-fat diets containing safflower or whole cottonseed respond similarly to cold stress, but these responses may not be consistent with greater cold resistance. In addition, high-fat dietary supplementation of late-gestation cows may only be beneficial during calving seasons with prolonged cold weather.

Effects of propofol containing EDTA on mineral metabolism in medical ICU patients with pulmonary dysfunction

OBJECTIVE

To determine whether the addition of disodium edetate (EDTA) to propofol significantly alters mineral metabolism, adverse events, and outcome in critically ill medical patients with acute pulmonary dysfunction.

DESIGN

Multicentre, double-randomised, double-blind, comparative trial.

SETTING

Medical intensive care units of 5 health centres.

PATIENTS

A total of 85 haemodynamically stable men and women aged 18-81 years who had pulmonary dysfunction or adult respiratory distress syndrome as a primary diagnosis or complication and who were expected to require at least 48 hours of sedation and mechanical ventilation.

INTERVENTIONS

Patients were randomised to receive propofol with or without EDTA and then to 1 of 2 sedation levels: light (Modified Ramsay Sedation Scale [MRSS] score of 2 to 3) or deep (MRSS score of 4 to 5). Propofol was administered by continuous infusion at an initial rate of 5 microg/kg per min and titrated as needed.

MEASUREMENTS AND RESULTS

Approximately 63 % of patients had a high severity of illness as indicated by an Acute Physiology and Chronic Health Evaluation II score > or = 19. As expected, these patients had a higher mortality rate but did not require a higher dose of propofol or propofol with EDTA. Extensive evaluation of cation homeostasis showed that ionised calcium and magnesium concentrations remained remarkably stable during treatment. Total calcium concentration was low as a result of hypoalbuminemia. Parathyroid hormone (PTH) concentration was elevated in both study groups at baseline, on day 4, and at the end of sedation. There were no significant differences in electrolyte levels and no progression to renal dysfunction. There were also no significant differences in haemodynamic or adverse-event profiles. Treatment-related adverse events occurred in 5 patients in each group; 4 of these (in 3 patients receiving propofol and 1 patient receiving propofol with EDTA) were considered serious. Because a large percentage of patients experienced a change in sedation level, no analyses were performed using sedation level.

CONCLUSIONS

The addition of EDTA to propofol does not alter calcium and magnesium homeostasis in critically ill patients with acute pulmonary dysfunction. The reason for the elevation in PTH concentrations in such patients is not known.

Safety and efficacy of propofol with EDTA when used for sedation of surgical intensive care unit patients

OBJECTIVE

To compare propofol with disodium edetate (EDTA) and propofol without EDTAwhen used for the sedation of critically ill surgical intensive care unit (ICU) patients.

DESIGN

Prospective, randomised, multicentre trial.

PATIENTS

A total of 122 surgical ICU patients who required intubation and mechanical ventilation.

INTERVENTIONS

Patients were randomised to receive either propofol or propofol plus EDTA (propofol EDTA) by continuous infusion for sedation.

MEASUREMENTS AND RESULTS

The addition of EDTA to propofol had no effect on calcium or magnesium homeostasis, renal function, haemodynamic function, or efficacy when used for the sedation of surgical patients in the ICU. The most common adverse events were hypotension, atrial fibrillation, and hypocalcaemia. In this trial, a greater number of serious adverse events and adverse events leading to withdrawal occurred in the propofol group relative to the propofol EDTA group. There was a significantly lower crude mortality rate at 7 and 28 days for the propofol EDTA group compared with the propofol group. There were no statistically significant differences between groups with respect to depth of sedation.

CONCLUSION

The propofol EDTA formulation had no effect on calcium or magnesium homeostasis, renal function, or sedation efficacy compared with propofol alone when used for sedation in critically ill surgical ICU patients. There was a significant decrease in mortality in the propofol EDTA group compared with the propofol group. Further investigations are needed to validate this survival benefit and elucidate a possible mechanism.