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

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.

Impact of delayed insemination on pregnancy rates to gender selected semen in a fixed-time AI system.

The objectives of the current experiment were to determine if delaying insemination by 8 h in a FTAI protocol would alter estrus expression and pregnancy rates in cows inseminated with sex-sorted semen, characterize bull variation in pregnancy rates to sex-sorted semen and examine the impact of repeated years of FTAI to sex-sorted semen on calving distribution. Over three breeding seasons, postpartum cows (n = 839) were estrous synchronized using the 5-day CO-Synch + CIDR system. Cows were given GnRH (100 µg i.m., Factrel) at time of insertion of a controlled internal drug releasing device (CIDR; Eazi-Breed CIDR). Five d later CIDR was removed and PGF2α (25 mg i.m., Lutalyse) was given at removal and 8 h later. Estrus detection aids were applied at CIDR removal. Cows were inseminated with X-sorted or Y-sorted sex-sorted semen at 72 h (NORM) or 80 h (DELAY) after CIDR removal, and GnRH was administered at AI. At insemination, estrus status was categorized as positive (YES), partial (QUES), unknown (NR) or negative (NO). Bulls were introduced to cows at 14 d and removed at 60 d after FTAI. Pregnancy diagnosis was performed by ultrasound at d 60 after FTAI and via palpation at 60 d after bull removal. There was no difference (P > 0.05) in pregnancy rates to sex-sorted semen or final pregnancy rates between NORM and DELAY cows. Pregnancy to sex-sorted semen averaged 35.2% whereas final pregnancy rates were 90.6%. More cows (P < 0.05) in the DELAY group expressed estrus before FTAI, but this increase did not alter pregnancy rates to sex-sorted semen. Expression of estrus before FTAI increased (P < 0.02) pregnancy rates to sex-sorted semen across treatments with differences being YES > QUES or NR > NO. There was considerable variation in pregnancy rate by bull (P < 0.05) with pregnancy rates ranging from 55.6% to 19.3%. Whole herd calving distribution was altered (P < 0.05) after 3 y of use of sex-sorted semen compared to the previous 3 y when conventional semen was used. We conclude that delaying insemination by 8 h in an FTAI protocol did not improve pregnancy rates to sex-sorted semen despite more cows exhibiting estrus before FTAI. In addition, a high bull to bull variation in pregnancy rates to sex-sorted semen is a limitation in FTAI systems. Further research into FTAI strategies for use with sex-sorted semen is warranted.

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

An experiment was designed to evaluate the relative fertility of SexedULTRATM 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 SexedULTRATM 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 F2α (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 PGF2α 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 SexedULTRATM 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 SexedULTRATM 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.

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14-day CIDR protocol.

This study compared artificial insemination pregnancy rate (AI-PR) between 14-day CIDR-GnRH-PGF2α-GnRH and CIDR-PGF2α-GnRH synchronization protocol with two fixed AI times (56 or 72 hr after PGF2α). On day 0, heifers (n = 1311) from nine locations assigned body condition score (BCS: 1, emaciated; 9, obese), reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic) and temperament score (0, calm; and 1, excited) and fitted with a controlled internal drug release (CIDR, 1.38 g of progesterone) insert for 14 days. Within herd, heifers were randomly assigned either to no-GnRH group (n = 635) or to GnRH group (n = 676), and heifers in GnRH group received 100 µg of GnRH (gonadorelin hydrochloride, IM) on day 23. All heifers received 25 mg of PGF2α (dinoprost, IM) on day 30 and oestrous detection aids at the same time. Heifers were observed for oestrus thrice daily until AI. Within GnRH groups, heifers were randomly assigned to either AI-56 or AI-72 groups. Heifers in AI-56 group (n = 667) were inseminated at 56 hr (day 32 PM), and heifers in AI-72 group (n = 644) were inseminated at 72 hr (day 33 AM) after PGF2α administration. All heifers were given 100 µg of GnRH concurrently at the time AI. Controlling for BCS (p < .05), RTS (p < .05), oestrous expression (p < .001), temperament (p < .001) and GnRH treatment by time of insemination (p < .001), the AI-PR differed between GnRH treatment [GnRH (Yes - 60.9% (412/676) vs. No - 55.1% (350/635); p < .05)] and insemination time [AI-56 - 54.6% (364/667) vs. AI-72 - 61.8% (398/644); (p < .01)] groups. The GnRH treatment by AI time interaction influenced AI-PR (GnRH56 - 61.0% (208/341); GnRH72 - 60.9% (204/335); No-GnRH56 - 47.9% (156/326); No-GnRH72 - 62.8% (194/309); p < .001). In conclusion, 14-day CIDR synchronization protocol for FTAI required inclusion of GnRH on day 23 if inseminations were to be performed at 56 hr after PGF2α in order to achieve greater AI-PR.

Fertility after implementation of long- and short-term progesterone-based ovulation synchronization protocols for fixed-time artificial insemination in beef heifers.

Two experiments were conducted to evaluate the effect of long-term (LT; a 14-day controlled internal drug release insert [CIDR]-PGF2α [PGF]-GnRH) and short-term (ST; 5-day CO-Synch + CIDR) progesterone-based protocols on pregnancy rate to fixed-time artificial insemination (FTAI) in beef heifers. In experiment 1, Angus cross beef heifers (N = 1887) at nine locations received a body condition score and a reproductive tract score (RTS). Within the herd, heifers were randomly assigned to LT-72 and ST-56 protocol groups. Heifers in the LT-72 group received a CIDR from Days 0 to 14, followed by 25 mg of PGF 16 days later (Day 30). Heifers in the ST-56 group received a CIDR and 100 µg of gonadorelin hydrochloride (GnRH) on Day 25 followed by 25 mg of PGF at CIDR removal on Day 30 and a second dose of PGF 6 hours later (Day 30). Artificial insemination was performed at 56 hours (Day 32) after CIDR removal for the ST-56 group and at 72 hours (Day 33) after CIDR removal for the LT-72 group, and all heifers were given GnRH (100 µg, intramuscular) at the time of AI. In experiment 2, Angus cross beef heifers (N = 718) at four locations received a body condition score and an RTS. Within the herd, heifers were randomly assigned to LT-72 and ST-72 protocol groups. The protocol was similar to experiment 1 except that AI was performed at 72 hours after CIDR removal for both LT-72 and ST-72 groups. In experiment 1, no difference in AI pregnancy rates between the LT-72 and ST-56 groups was observed (54.5% [489 of 897] and 55.5% [549 of 990], respectively; P = 0.92) after accounting for the RTS. The AI pregnancy rates for heifers with RTS 3 or less, 4, and 5 were 52.6%, 53.6%, and 59.9%, respectively (P < 0.05). In experiment 2, controlling for the RTS, no difference in AI pregnancy rates was observed between the LT-72 and ST-72 groups, 56.9% (198 of 347) and 57.8% (214 of 371), respectively (P = 0.87). The AI pregnancy rates for heifers with RTS 3 or less, 4, and 5 were 49.3%, 58.4%, and 62.1%, respectively (P < 0.05). In conclusion, heifers synchronized for fixed-time AI with LT and ST protocols resulted in a similar AI pregnancy rate. Approximately, 55% of the herd was pregnant to one insemination in 33 days with the LT protocol compared with just 8 days with the ST 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.

Effect of the first GnRH and two doses of PGF2α in a 5-day progesterone-based CO-Synch protocol on heifer pregnancy.

The objectives were (1) to determine the effects of gonadorelin hydrochloride (GnRH) injection at controlled internal drug release (CIDR) insertion on Day 0 and the number of PGF2α doses at CIDR removal on Day 5 in a 5-day CO-Synch + CIDR program on pregnancy rate (PR) to artificial insemination (AI) in heifers; (2) to examine how the effect of systemic concentration of progesterone and size of follicles influenced treatment outcome. Angus cross beef heifers (n = 1018) at eight locations and Holstein dairy heifers (n = 1137) at 15 locations were included in this study. On Day 0, heifers were body condition scored (BCS), and received a CIDR. Within farms, heifers were randomly divided into two groups: at the time of CIDR insertion, the GnRH group received 100 µg of GnRH and No-GnRH group received none. On Day 5, all heifers received 25 mg of PGF2α at the time of CIDR insert removal. The GnRH and No-GnRH groups were further divided into 1PGF and 2PGF groups. The heifers in 2PGF group received a second dose of PGF2α 6 hours after the administration of the first dose. Beef heifers underwent AI at 56 hours and dairy heifers at 72 hours after CIDR removal and received 100 µg of GnRH at the time of AI. Pregnancy was determined approximately at 35 and/or 70 days after AI. Controlling for herd effect (P < 0.06), the treatments had significant effect on AI pregnancy in beef heifers (P = 0.03). The AI-PRs were 50.3%, 50.2%, 59.7%, and 58.3% for No-GnRH + PGF + GnRH, No-GnRH + 2PGF + GnRH, GnRH + PGF + GnRH, and GnRH + 2PGF + GnRH groups, respectively. The AI-PRs were ranged from 50% to 62.4% between herds. Controlling for herd effects (P < 0.01) and for BCS (P < 0.05), the AI pregnancy was not different among the treatment groups in dairy heifers (P > 0.05). The AI-PRs were 51.2%, 51.9%, 53.9%, and 54.5% for No-GnRH + PGF + GnRH, No-GnRH + 2PGF + GnRH, GnRH + PGF + GnRH, and GnRH + 2PGF + GnRH groups, respectively. The AI-PR varied among locations from 48.3% to 75.0%. The AI-PR was 43.5%, 50.4%, and 64.2% for 2.5 or less, 2.75 to 3.5, and greater than 3.5 BCS categories. Numerically higher AI-PRs were observed in beef and dairy heifers that exhibited high progesterone concentrations at the time of CIDR insertion (>1 ng/mL, with a CL). In addition, numerically higher AI-PRs were also observed in heifers receiving CIDR + GnRH with both high and low progesterone concentration (<1 ng/mL) initially compared with heifers receiving a CIDR only with low progesterone. In dairy heifers, there were no differences in the pregnancy loss between 35 and 70 days post-AI among the treatment groups (P > 0.1). In conclusion, GnRH administration at the time of CIDR insertion is advantageous in beef heifers, but not in dairy heifers, to improve AI-PR in the 5-day CIDR + CO-Synch protocol. In addition, in this study, both dairy heifers that received either one or two PGF2α doses at CIDR removal resulted in similar AI-PR in this study regardless of whether they received GnRH at CIDR insertion.

An examination of the association of serum IGF-I concentration, potential candidate genes, and fiber type composition with variation in residual feed intake in progeny of Red Angus sires divergent for maintenance energy EPD.

Investigating the genetic and physiological drivers of postweaning residual feed intake (RFI) and finishing phase feed efficiency (FE) may identify underlying mechanisms that are responsible for the variation in these complex FE traits. The objectives were 1) to evaluate the relationship of serum IGF-I concentration and muscle gene expression with postweaning RFI and sire maintenance energy (MEM) EPD and 2) to determine fiber type composition as it relates to postweaning RFI and finishing phase FE. Results indicate that RFI and serum IGF-I concentration were not associated (P > 0.05); however, negative correlations (P < 0.05) between sire MEM EPD and serum IGF-I concentration were observed. Gene expression differences between high- and low-RFI animals were observed in cohort 1, where IGFBP5 expression was greater (P < 0.05) in high-RFI animals. When animals were grouped according to sire MEM EPD, the low MEM EPD group of cohort 1 showed greater muscle mRNA expression (P < 0.01) of fatty acid synthase (FASN) and marginally (P < 0.10) greater expression of IGFBP5 and C/EBP alpha (C/EBPα) whereas the high MEM EPD group of cohort 2 had greater muscle mRNA expression of IGFBP2 (P < 0.05) and C/EBPα (P ≤ 0.01) and marginally (P < 0.10) greater expression of IGFBP3. Biopsy tissue samples collected at harvest revealed that the percentage of type IIa fibers was lower (P ≤ 0.05) in high-RFI steers, with a similar trend (P < 0.10) being observed in high finishing phase FE steers. The percentage of type IIb fibers was higher (P < 0.05) in high-RFI (and finishing phase FE) steers than in low-RFI (and finishing phase FE) steers. There was a marginal, negative correlation between RFI and type I (r = -0.36, P = 0.08) and IIa (r = -0.37, P = 0.07) fiber percentages and a positive correlation (r = 0.48, P = 0.01) between RFI and type IIb fiber percentage whereas finishing phase FE was negatively correlated (r = -0.43, P = 0.03) with type I fiber percentage and positively correlated (r = 0.44, P = 0.03) with type IIb fiber percentage. Therefore, our data indicate that 1) serum IGF-I (collected at weaning) is not an indicator of postweaning RFI, 2) the GH-IGF axis appears to have some involvement with RFI at the molecular level; however, muscle gene expression results were not consistent across cohorts, and 3) low-RFI animals may have the ability to more efficiently maintain and accrete muscle mass due to their fiber type composition, specifically a greater proportion of type I fibers.

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 - ß = 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.

Effect of time from estrus to AI on pregnancy rates in estrous synchronized beef heifers.

For the last 65 years, the industry standard for time of artificial insemination (AI) relative to onset of estrus has been established as 12 h after observed estrus. More recent experiments indicated the optimum time for AI was 4-12 h after onset of estrus in dairy cattle, but little recent information is available on the effect of time of AI relative to the onset of estrus in beef cattle. Therefore, we conducted a retrospective study on the impact of time from onset of estrus to artificial insemination using records from estrous synchronized crossbred Angus heifers (n=1205). Data were compiled from experiments on estrous synchronization systems and AI where estrous detection was performed electronically with HeatWatch(®). Only data from heifers detected in estrus was used. Heifers averaged 440 days of age, and weighed 368 kg at insemination. Heifers were assigned to one of the following 4h blocks of time based on time from onset of estrus (hour 0) to insemination: 0-4 (n=79), 4-8 (n=163), 8-12 (n=211), 12-16 (n=163), 16-20 (n=193), 20-24 (n=149), >24 h (n=247). Pregnancy rates to AI were not affected by AI technician or season of breeding (P>0.80). However, time of insemination relative to onset of estrus affected (P<0.01) pregnancy rates to AI. Heifers inseminated between 4 and 24h after onset of estrus had greater AI pregnancy rates (P<0.05; 63.7%) compared to the 0-4h (48.1%) and >24h (55.9%) groups. The time period for achieving acceptable pregnancy rates to AI in beef heifers appears to be approximately 20 h in length. Estrous synchronization programs resulting in a majority of heifers in estrus between 4 and 24 h before AI should yield the greatest pregnancy rates.

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.

Effects of one versus two doses of prostaglandin F2alpha on AI pregnancy rates in a 5-day, progesterone-based, CO-Synch protocol in crossbred beef heifers.

The present study determined whether a 5-d progesterone-based CO-Synch protocol with a single dose of prostaglandin F(2α) (PGF) at progesterone withdrawal on Day 5, would yield a timed AI pregnancy rate similar to two doses of PGF given 6 h apart on Day 5. Angus cross beef heifers (N = 562) at six locations were used. All heifers received 100 µg of gonadorelin hydrochloride (GnRH) and a controlled internal drug release (CIDR) insert on Day 0. Within farm, heifers were randomly allocated to receive one dose of 25 mg dinoprost (PGF) at CIDR removal on Day 5 (1 PGF; N = 264), or two doses of 25 mg PGF, with the first dose given on Day 5 at CIDR removal, and the second dose 6 h later (2 PGF; N = 298). Most heifers (N = 415) received a heat detector patch at CIDR removal. After CIDR removal, heifers were observed twice daily through Day 7 for estrus and heat detector aid status was recorded. On Day 8, heifers were given 100 µg of GnRH, heat detector aid status was recorded, and heifers were inseminated approximately 72 h after CIDR removal. Accounting for significant variables such as location (P < 0.01), heifers in estrus at or prior to AI (P < 0.001), and a treatment by location interaction (P < 0.01), two doses of PGF on Day 5 tended to have higher pregnancy rates to timed AI compared to those that received one dose of PGF (P = 0.06). In conclusion, heifers given two doses of PGF at CIDR removal on Day 5, in a 5-d CIDR-CO-Synch protocol, tended to have a higher pregnancy rate than those that received only one dose of PGF.

Pregnancy rates in angus cross beef cows bred at observed oestrus with or without second GnRH administration in fixed-time progesterone-supplemented Ovsynch and CO-Synch protocols.

Crossbred cows (n = 1073) from five locations had oestrous cycles synchronized with 100 microg of GnRH IM and insertion of controlled internal drug release device (CIDR) on Day 0 followed by 25 mg of PGF(2alpha) IM and CIDR removal on Day 7. Kamar patches were placed on all cows at CIDR removal. Cows were observed three times daily for oestrus after PGF(2alpha) administration. In the Ovsynch-CIDR group, cows detected in oestrus (n = 193) within 48 h after PGF(2alpha) were inseminated using the AM-PM rule. Among these cows, 80 received and 113 did not receive a second GnRH at 48 h after PGF(2alpha). Cows (n = 345) not detected in oestrus received a second GnRH at 48 h after PGF(2alpha) on Day 9, and fixed-time AI 16 h after the GnRH on Day 10. In the CO-Synch-CIDR group, cows detected in oestrus (n = 224) within 48 h after PGF(2alpha) were inseminated using the AM-PM rule. Among these cows, 79 received and 145 did not receive a second GnRH at 64 h after PGF(2alpha). Cows (n = 311) not detected in oestrus received a second GnRH on Day 10 at the time of AI, 64 h after PGF(2alpha). The AI pregnancy rates were not different between the Ovsynch-CIDR and CO-Synch-CIDR groups (p = 0.48). There were no differences in the AI pregnancy rates for cows inseminated at a fixed time (p = 0.26) or at detected oestrus (p = 0.79) between the treatment groups. Among cows inseminated in oestrus, there were no differences in the AI pregnancy rates between cows that received or did not receive the second GnRH (p = 0.47). In conclusion, acceptable AI pregnancy rates can be achieved with or without inclusion of oestrus detection in the Ovsynch-CIDR and CO-Synch-CIDR protocols. Among cows detected in oestrus, cows that received a second GnRH yielded similar pregnancy rates when compared with cows that did not receive the second GnRH.

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.