Heat Mount Detectors Research Articles

Effects of Beta-carotene Administration on Fertility in Lactating Dairy Cows

Background: Beta-(β-) carotene, is the precursor to vitamin A, in particular, has some potential benefits on reproduction. The main objective of this study was to investigate the efficacy of β-carotene administration on fertility following either prostaglandin F2 alpha (PGF) induced estrus or Ovsynch protocol in lactating dairy cows.Methods: Cows with at 47±3 postpartum days were divided into two groups: β-carotene group (βC, n=139) was treated with injectable β-carotene while untreated cows served as control (CON, n=227). In both groups, PGF was administered and heatmount detectors were applied at 54±3 days postpartum. Cows detected in estrus after PGF were inseminated. Cows that had not been detected in estrus were divided into two groups 7 days after PGF administration; βC-OVS (n=137) and CON-OVS (n=89). Ovsynch protocol was initiated 4 days after β-carotene administration.Result: The estrus detection rate was similar between the βC and CON groups (P = 0.19). Pregnancy per AI (P/AI) on d 31 was also similar between groups (P = 0.93). In the Ovsynch protocol, ovulation to the first GnRH and ovulatory follicle diameter at the time of insemination did not differ between groups. No difference was observed in P/AI at d 31 (P = 0.13). The results of this study indicated that β-carotene administration had no effect on fertility either PGF induced estrus or Ovsynch protocol in dairy cows.

108 Synchronization and artificial insemination of South African communal cattle

The present study aimed to evaluate an oestrous synchronization protocol and oestrus response before AI in cows from an organised communal production system. A total of 74 cows Bos indicus (Brahman) and Bos taurus/indicus hybrid (Nguni) type from different communal farmers were screened based on: age (3 to 8 years), body condition score of ≥3 (1–5 scale), not pregnant (excluding heifers), 90 days postpartum, number of parities, good mothering ability, and negative for contagious abortion. Selected cows were subjected to a 9-day OvSynch+CIDR protocol. In brief, the protocol included the insertion of controlled intravaginal drug release (CIDR®, Pfizer Laboratories) devices in the reproductive tract (vagina) containing 1.9g of progesterone in each cow on Day 0 with first oestradiol benzoate (Oestradiol benzoate®, VTech) 2-mL intramuscular (IM) injection. Pregnant mare serum gonadotrophin (PMSG; Chronogest®, Intervet International B.V.) 2.5-mL (IM) injection on Day 5. Removal of CIDR and (IM) injection of prostaglandin F2α (PGF2α; Estrumate®, Intervet South Africa (Pty.) Ltd.) 2mL on Day 8. Following CIDR removal, a heat mount detector (Kamar®) was applied on the individual cow’s tail head for oestrus observation (signs of heat) with second oestradiol benzoate 1-mL (IM) injection on Day 9. AI was performed 36h following withdrawal of the CIDR. Frozen/thawed semen from Bonsmara bulls (n=2) of known and proven fertility was used for AI. The GameteTek Cryo-Mobile laboratory was used during thawing of semen straws. and sperm motility and morphological traits were immediately evaluated by computer-assisted sperm analysis (Sperm Class Analyzer®) before each individual cow was inseminated. Pregnancy diagnosis was performed 90 days after timed AI by ultrasound and transrectal palpation. Data were analysed using the logistic regression procedure of SAS (SAS Institute Inc.), with synchronisation response and conception being treated as binary response variables. All cows were synchronized successfully and an oestrus response rate of 100% was recorded. Pregnancy rates were similar (37.8% vs. 38.9%) for both Bos indicus and Bos taurus/indicus hybrid cattle. Bulls total sperm motility of ≥75% were recorded, following thawing of semen straws. Thus, there was no effect of bull on pregnancy. In conclusion, acceptable oestrus synchronization response was achieved in this communal setup. Superior genetic materials can be successfully introduced through assisted reproductive technologies in organised communal production systems.

Estrous characteristics and reproductive outcomes of Holstein heifers treated with 2 prostaglandin formulations and detected in estrus by an automated estrous detection or mounting device

Dinoprost tromethamine (DIN), a molecule similar to endogenous PGF2α, has a half-life of approximately 9 min. Cloprostenol sodium (CLO), a synthetic analog of PGF2α, has a half-life of approximately 3 h. We hypothesized that treatment of Holstein heifers with CLO would improve estrous detection rate, estrous characteristics, service rate, and overall reproductive performance compared with DIN. Currently in the United States, heifers are largely inseminated based on signs of estrus, which is detected visually or with the aid of mounting detection devices (MD). Automated estrous detection devices (AED) are becoming more accessible to producers, but it is not clear whether they present advantages in the reproductive management of heifers. Therefore, we hypothesized that the use of an AED would improve service and pregnancy rates compared with detection of estrus with the aid of a MD. Holstein heifers (n = 1,019) were enrolled in the experiment at 10 to 11 mo of age, when they were fitted with a Heatime HR LD System (SCR Ltd., Netanya, Israel). At 12 mo of age, we paired heifers according to estrous cycle phase and randomly assigned them to treatments in a 2 × 2 design: PGF2α formulation (CLO vs. DIN) and estrous detection treatment (AED vs. MD). Heifers in the AED treatment were detected in estrus only by the Heatime HR LD System, whereas heifers in the MD treatment were detected in estrus only by the Kamar Heatmount Detector (Kamar Products Inc., Zionsville, IN). Treatments with the same PGF2α formulations were repeated 14 d after the first treatment if heifers had not been detected in estrus. A sub-group of heifers had blood sampled on the day of PGF2α treatment and within 24 h of onset of estrus to determine progesterone and estradiol concentrations. Treatment with CLO reduced the progesterone concentration within 24 h of onset of estrus compared with DIN (0.04 ± 0.01 vs. 0.11 ± 0.01 ng/mL). Among heifers in mid diestrus on the day of PGF2α treatment, CLO reduced the interval to estrus compared with DIN (72.0 ± 2.2 vs. 82.4 ± 2.4 h). Prostaglandin F2α formulation and estrous detection treatment did not affect pregnancy to the first service. The interval between the first and second services tended to be reduced for the AED treatment compared with the MD treatment (24.4 ± 0.5 vs. 25.7 ± 0.6 d). Prostaglandin F2α formulation and estrous detection treatment did not affect the hazard of pregnancy. Although CLO treatment may shorten the interval to estrus in heifers at mid diestrus compared with DIN, PGF2α formulation did not affect reproductive performance. In the current experiment, no advantages in reproductive performance were observed when estrous detection was based on an AED compared with a MD.

Using temporal associations to determine postpartum oestrus in tropical beef cows

The radio frequency identification (RFID) technology introduced with the National Livestock Identification System has increased the precision of livestock management. Tag readers incorporated in walk-over-weighing systems have enabled automated collection of daily RFID sequential data as cattle access water. The temporal sequence of individuals accessing a watering point in a rangeland grazing system could potentially provide knowledge of key aspects of animal behaviour. The current study investigated the use of the shortest daily average interval of time from cow to bull (TTB) coming to water over a 29-day period to predict postpartum oestrus events. Fifteen Brahman and 15 Belmont Red cows mated to bulls of the same breed in separate paddocks were fitted with proximity loggers, heat-mount detectors and were ovarian-scanned with ultrasonics to determine the timing of postpartum oestrus. The data collected from these devices were compared with RFID sequence data of the bulls following cows to water to evaluate whether TTB alone could predict oestrus activity. At the start of the experimental period, mean (±s.d.) weight and days postpartum of the Brahman cows were 527 (±43.4) kg and 89 (±18.4) days respectively, and of the Belmont Red cows 513 (±54.1) kg and averaged 66 (±19.6) days postpartum. Six of the 15 Brahman cows and 9 of the 15 Belmont Red cows displayed oestrus activity, as indicated by increased contact with the bull, an activated heat-mount detector and the presence of an ovarian corpus luteum. The sensitivity and specificity of TTB as an indicator of oestrus events across the groups were 0.65 and 0.60 respectively. Temporal sequence data have the potential to contribute to the determination of oestrus and date of conception.

16 Evaluation of Factors Influencing Timed Artificial Insemination in South African Communal Cows

In South Africa, assisted reproductive technologies (ART) such as oestrus synchronization and AI in cattle have traditionally been applied in commercial production systems but not communal production systems because of several challenges such as infrastructure and cost. The study was designed to assess factors affecting response to oestrus synchronization, conception, and calving rate of organised communal cows following timed AI in Limpopo province, South Africa. A total of 140 cows were selected from organised communal villages and categorized according to body condition score (BCS), parity, age, frame size (small to medium) and breed type (Nguni, Bonsmara, and Brahman). A 9-day CIDR® (Pfizer Laboratories, New York, NY, USA) protocol was used to synchronize the selected cows. Heat mount detectors (Karma®; Four Lakes) were used to assess oestrous synchronisation responce. The AI was done twice at 36 and 48 h post-CIDR® removal using Nguni frozen–thawed semen. Pregnancy diagnosis was performed 90 days following AI using ultrasound scanner and trans-rectal palpation. Data on influence of factors such as BCS, parity, age, district, breed type, and frame size on oestrus response, conception and calving rate were analysed using logistic regression procedure of SAS. Of 140 cows synchronized, 75% (105/140) had tripped patches and underwent AI, 41% (43/105) conceived, and 36% (38/105) calved. Parity, age, breed type, and frame size did not significantly affect oestrous synchronisation response, conception, and calving rate. However, BCS significantly (P = 0.0042) affected calving rate, whereby cows in BCS of >3 had a greater probability of success than those with BCS ≤3. Small-framed Nguni and Bonsmara type cows in their first parity with a BCS ≥3 had greater odds of conceiving following timed AI. Noteworthy, calving rate in the current study was comparable to other studies under communal areas (South African Vet. Assoc. 2004 75, 30-36; Appl. Anim. Husb. Rural Develop. 2013 6, 48-54). Therefore, the current study demonstrated an opportunity to improve the production of organised communal cattle using superior sire germplasm though assisted reproductive technologies. Cows in organised communal areas have greater probability of conceiving and calving when their condition score is >3, regardless of their age, parity, size, or breed type. It is concluded, therefore, that AI technology should be applied in cows of organised communal farmers to facilitate dissemination and propagation of superior germplasm.

15 QUANTIFICATION OF BULL SPERM TRAITS AS ASSESSED BY COMPUTER-ASSISTED SEMEN ANALYSIS AND THE RELATIONSHIP TO PREGNANCY RATE FOLLOWING CONTROLLED BREEDING

The bull’s contribution through artificial insemination to reproductive efficiency is of great biological importance. The objectives were (1) to compare the oestrous synchronization response of Bonsmara and Nguni cows; and (2) to find the relationship between cow’s conception rate (in vivo and in vitro fertilization) and bull sperm motility rate assessed by computer-assisted semen analysis (CASA) following AI. For the in vivo sperm fertility test, 100 Bonsmara and 482 Nguni cows were randomly selected and subjected to oestrous synchronization protocol and AI with frozen–thawed assessed semen by CASA before AI. Briefly at Day 0, cows were inserted with an intravaginal CIDR® (1.9 g), which was removed on Day 7. Prostaglandin was then administered (2 mL) on Day 8 and a heatmount detector was placed on the hindquarter of each cow. For the in vitro sperm fertility test, collected oocytes from slaughterhouse were in vitro matured (n = 360) and in vitro fertilized (sperm/mL) in 100-µL droplets (final volume) of BO-IVF medium per treatment bulls (Bonsmara or Nguni bull). The frozen/thawed semen straws of Bonsmara and Nguni bulls were randomly selected and used under the same IVF conditions. The thawed bull’s sperm characteristics were examined by CASA before in vitro fertilization. Data were analysed using ANOVA. Treatment means were compared using the Fisher’s protected least significant difference t-test. There was no significant difference in oestrous response for the Bonsmara (83.0%) and Nguni (90.8%) cows, respectively. The Bonsmara cows recorded a significantly higher pregnancy rate (59.0%) compared with the Nguni (37.1%) cows (P < 0.05). Sperm traits such as total motility (TM), progressive motility and rapid were found to be positively correlated with conception rate (r = 0.06, 0.03, and 0.08, respectively; P < 0.01), although correlations were low. There was no difference in the average frozen–thawed sperm TM rate of Nguni (92.2%) and Bonsmara (81.0%). There was a lower fertilization rate following IVF with Bonsmara and Nguni bull sperm. In conclusion, Nguni cows had similar oestrous response as Bonsmara cows. The sperm traits from Bonsmara and Nguni bulls were found to be related to in vivo conception and in vitro fertilization rate when sperm cells were assessed by CASA technology. However, the pregnancy rate was lower in Nguni cows.

Comparison of Oestrous Synchronization Response and Pregnancy Rate of Village Cows Following Timed Artificial Insemination in KwaZulu-Natal and Limpopo Provinces

The objectives of the current study were to evaluate the estrous response and pregnancy rate following timed artificial insemination (TAI) with frozen-thawed semen in cows. The study was carried out in cows at different villages of KwaZulu-Natal (KZN; n = 160) and Limpopo provinces (L; n = 171). Cows were selected randomly as presented by the farmers, regardless of parity, age, breed and body weight following pregnancy diagnosis. The cows were grouped according to breed type and body condition score (BCS) on a scale of 1-5. Selected cows were inserted a controlled intravaginal drug release (CIDR&#174) and removed on day 8, followed by administration of prostaglandin. Heat was observed on day 9 with the aid of heat mount detectors (HMD) that were placed on the individual cow’s tail head. Cows on heat were then inseminated twice at 12 hours interval. Pregnancy diagnosis was performed by an ultrasound scanner and rectal palpation 90 days after TAI. Data were analyzed using SAS 2006. Estrous responses were 100% in KZN and 99% in Limpopo. The lowest pregnancy rate was recorded in Brahman and Bonsmara type cows with BCS ≤ 2.5 regardless of province. Interestingly, Nguni type cows with BCS ≤ 2.5 had higher average pregnancy rate of 59.5% in Limpopo and 53.5% in KZN. However, cows with BCS ≥ 3 had better pregnancy rate regardless of breed type and province. In conclusion, village cows can be synchronized successfully and inseminated with frozen-thawed semen. However, pregnancy rates are low in cows with lower body condition. Village Nguni type cows were not affected by body condition scoring as they had higher and similar pregnancy rate as those that had body condition of ≥3.

8 RESPONSE OF COMMUNAL COWS TO OESTRUS SYNCHRONIZATION AND TIMED ARTIFICIAL INSEMINATION

Reproductive technologies such as oestrus synchronization and AI have been tested in controlled environments in the commercial farms in South Africa but not in an uncontrolled communal setup. The aims of the study were to evaluate the response of communal cows to oestrus synchronization and timed AI. The effects of age and body condition score (BCS) on oestrus response and conception rate were also studied. A total of 96 cows were selected from the communal villages. Cows with the BCS of 2.5 to 4.5 (on a scale of 1–5) and age between 3 and 10 years were used. Cows were grouped into 2 BCS groups (<3 and = 3) and 2 age groups (<6 and = 6). All groups were subjected to a 9-day Ovsynch + CIDR (CIDR®; Pfizer Laboratories, New York, NY, USA) protocol. A CIDR® was inserted into the vagina on Day 0 (random days of the cycle), and 2 mg of oestradiol benzoate (Ciderol®; Pfizer Laboratories) was administered. On Day 8, the CIDR® was removed, and the cows were administered with 500 μg of cloprostenol (PGF; Estrumate®, Schering-Plough Animal Health). In addition, on Day 9, cows were given 1 mg of oestradiol benzoate, and a heat mount detector (Karma®; Four Lakes) was placed on the tail head of the cows to detect oestrus response (standing heat). All the synchronized cows were then inseminated at 36 and 42 h with frozen-thawed Nguni bull semen following oestradiol benzoate injection. Pregnancy diagnosis was performed 90 days following timed AI using ultrasound scanner and transrectal palpation. Data were analysed using ANOVA. An overall 73% oestrus response and 45% conception rate were achieved in this study. There was no significant difference in oestrus response in cows with a BCS <3 (67%) and = 3 (83%) or age <6 (77%) and = 6 (72%). There was no significant difference in conception rate between those <6 (41%) and = 6 (47%) years of age. However, cows with a BCS of = 3 had greater (P < 0.05) conception rate (55%) compared with those with a BCS <3 (35%). In conclusion, communal cows responded to an oestrus synchronization program involving timed AI. The BCS and age did not alter the oestrus response, but conception rate was higher in communal cows with BCS of = 3.

Multiple Ovulation and Non-Surgical Embryo Transfer in Cattle by Using Intravaginal Controlled Internal Drug Release (CIDR) Progesterone Inserts

This paper has been presented to share the protocol and techniques of multiple ovulation and non-surgical embryo transfer in cattle among Nepalese animal scientists. Three elite Holstein cows kept for research and study purpose in the animal farm of the University of Queensland, Gatton, Australia were selected as donors of the embryo for this multiple ovulation and embryo transfer program. Similarly, 11 Holstein heifers of age 14 to 20 months from the same farm were selected as recipients for the program. Synchronization of estrus in both donor and recipients and superovulation in donor has been done by using intravaginal controlled internal drug release (CIDR) progesterone inserts, GnRH, FSH and PGF2á as per a set protocol. Oestrus was detected by heat mount detector and artificial insemination in donors was done immediately after detecting heat and repeated every 12 hours for 2 to 3 times with semen of proven bulls. Embryos from the donors were recovered by flushing using Foley catheter. The embryos were then evaluated microscopically according to the stage of development and quality of them. The embryos were non-surgically transferred into recipients by using embryo transfer gun. Unrecovered embryos were terminated by injecting PGF2á after 6 days. The pregnancies in recipients were diagnosed on 45th day of transfer by real time ultrasonography (USG). All of the recipients (100%) came in estrus within 72 hours of removal of CIDR while it took 96 hours after removal of CIDR to donors to show the sign of estrus. Sixteen embryos were recovered from three donors out of which 11 (68.75 %) were transferable. Number of transferable embryos could be collected from one donor which could affect the average result. Five cows (62.5%) were pregnant when diagnosed by ultrasonography (USG) after 7 weeks. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 15-22 DOI: http://dx.doi.org/10.3126/njst.v14i1.8872

Technologies Related with the Artificial Insemination in Buffalo

In buffalo oestrus behaviour has a lower intensity than in cows and is much more difficult to detect, limiting the application of artificial insemination (AI) program. Several methods of heat detection have been developed for use in cattle; these include visual observation, heat mount detectors, tail paint, chin-ball markers, teaser animals and electronic devices. In buffalo, unlike cattle, the female are receptive to mounting activity mainly by the bull and occasionally by other cows. Consequently unless a buffalo bull is to be left running with the herd it can be difficult to know when oestrus is occurring. The presence of a teaser bull is helpful to identify buffaloes in heat; in this case the standing oestrus is the most reliable sign referable to a next ovulation. Other heat detection aids utilized in buffalo include: pedometers; vaginal probes; pressure sensitive telemetry device (Heat Watch®). In order to increase the use of AI easy management schemes, that not require the identification of oestrus, have been studied. These schemes are based on the manipulation of the hormonal events occurring during the oestrous cycle as: manipulate peripheral progesterone concentration (by PGF2a or progesterone releasing device); manipulate follicular growth and timing of ovulation (by GnRH and PGF2a). A brief description of these technologies, with special reference to synchronization protocols to apply fixed time AI in buffalo, are presented in this review. The potential application of predetermining the sex of offspring will be also discussed, with reference to the techniques available for commercial practice in buffalo.

Comparison of oestrus detection methods in dairy cattle

Sixty-seven Holstein-Friesian cows, from 20 days postpartum, were recruited into the study and fitted with both a pedometer (SAE Afikim) and a Heatime neck collar (SCR Engineers) and allocated a...

Comparison in Effect of Heatsynch with Heat Detection Aids and CIDR‐Heatsynch in Dairy Heifers

The objective of the present study was to determine whether oestrous detection with the help of oestrous detection aids during the Heatsynch without timed AI protocol is equally effective with the progesterone-combined protocol in dairy heifers. A total of 148 heifers were randomly assigned to one of the two groups. A group of heifers treated with Heatsynch with heat detection aids (n = 72) received GnRH on day 0, prostaglandin F(2alpha) (PGF(2alpha)) on day 7 and oestradiol benzoate (EB) on day 8, while in controlled internal drug release (CIDR)-Heatsynch group (n = 76), CIDR was included during a period from GnRH to PGF(2alpha). Heifers were checked for oestrus twice daily, i.e. from 09:00 to 10:00 hours and from 15:00 to 16:00 hours starting on day 2 for Heatsynch group and on day 8 in CIDR-Heatsynch group, and continued up to day 12. KAMAR heat mount detector (KAMAR Inc., Steamboat Springs, CO, USA) and ALL-WEATHER PAINTSTIK (LA-CO Industries Inc., Elk Grove Village, IL, USA) were used as heat detection aids. AI was conducted within 1 h after confirming oestrus in 72 heifers, while 19 animals were transferred with embryo 7 days after oestrus according to the request of the owners. Premature oestrus before PGF(2alpha) injection occurred in 18% of Heatsynch group. Of 13 heifers which showed premature oestrus, six were inseminated and two of them conceived. Oestrus detection rate within 12 days after initiation of the protocols did not differ between the two groups (94% vs 95%). There was no difference in the conception rate after first AI (including heifers that were inseminated before PGF(2alpha) injection) and embryo transfer between Heatsynch with heat detection aids and CIDR-Heatsynch groups (36% vs 44% and 70% vs 56%). It is concluded that the use of heat detection aids to monitor the occurrence of premature oestrus prior to PGF(2alpha) injection in Heatsynch protocol in dairy heifers was equally effective to the inclusion of CIDR.

Growth and reproductive performance of beef heifers grazing endophyte-free, endophyte-infected and novel endophyte-infected tall fescue

A three-year study was conducted to investigate the effects of endophyte-free (E−), endophyte-infected (E+) and novel endophyte-infected (EN) tall fescue on the growth and pregnancy rate of beef heifers during the spring. Each year, 48 beef heifers were strip-grazed on stockpiled fescue from December through February, fed fescue hay during late February to early April and then rotationally grazed on spring growth of fescue until June. At the end of the trial, heifers had been maintained on E+, E− or EN (pasture or hay) for a total of 152, 188 and 191 d in years 1, 2, and 3, respectively. In late March, heifers were synchronized using a controlled intravaginal drug-releasing device, (CIDR®) for 7 d followed by injection with PGF2α (Lutalyse®). Heatmount detectors (Kamar®) and observation for behavioral estrus were used to detect estrus for 63 d. Heifers were artificially inseminated 8 to12 h after the onset of standing estrus. Conception was determined by transrectal ultrasonography at approximately 30, 60 and 90 d after synchronization. Reproductive performance did not differ among treatments ( P ≥ 0.20). Pregnancy rate was 54, 65, and 65% for E+, E− and EN, respectively. However, during the spring, growth and prolactin were decreased ( P < 0.01) for heifers on E+. Gains on spring pasture were 0.24, 0.75, and 0.71 kg/d (SEM ± 0.03) for E+, E− and EN, respectively. Based on these results, the wild type endophyte-infected fescue can be used in production systems as a source of winter forage but producers should consider placing heifers on alternative forage (such as the novel endophyte-infected fescue) in the spring.

Detection of Anovulation by Heatmount Detectors and Transrectal Ultrasonography Before Treatment with Progesterone in a Timed Insemination Protocol

Our objective was to determine the accuracy of identifying noncycling lactating dairy cows before the application of a timed artificial insemination (AI) protocol [with or without progesterone supplementation via a controlled internal drug-release (CIDR) insert and 2 different timings of AI] by using heatmount detectors and a single ovarian ultrasound examination. At 6 locations in the Midwest, 1,072 cows were enrolled in a Presynch protocol (2 injections of PGF2α 14 d apart), with the second injection administered 14 d before initiating the Ovsynch protocol (injection of GnRH 7 d before and 48h after PGF2α injection, with timed AI at 0 or 24h after the second GnRH injection). Heatmount detectors were applied to cows just before the first Presynch injection, assessed 14 d later at the second Presynch injection (replaced when activated or missing), and reassessed at initiation of the Ovsynch protocol. Ovaries were examined for the presence of a corpus luteum (CL) by ultrasound before the initiation of treatment. Treatments were assigned to cows based on the presence or absence of a CL detected by ultrasound: 1) no CL + no CIDR; 2) no CL + CIDR insert for 7 d; and 3) CL present. Further, alternate cows within the 3 treatments were assigned to be inseminated concurrent with the second GnRH injection of Ovsynch (0h) or 24h later. Pregnancy was diagnosed at 33 and 61 d after the second GnRH injection. By using low (<1 ng/mL) concentrations of progesterone in serum as the standard for noncycling status, heatmount detectors were activated on a large percentage of noncycling cows (>60%), whereas the single ultrasound examination incorrectly classified noncycling cows only 21% of the time. Conversely, cycling cows (progesterone ≥1 ng/mL) were correctly identified 70 to 78% of the time by heatmount detectors, but 85 to 92% were correctly identified by ultrasound. Overall accuracy of heatmount detectors and ultrasound was 71 and 84%, respectively. Application of progesterone to cows without a CL at the time of the first injection of GnRH reduced the incidence of ovulation but increased the proportions of pregnancies per AI at d 33 or 61 compared with nontreated cows without a CL at the onset of the Ovsynch protocol. Percentages of cows pregnant and pregnancy survival did not differ for cows having a CL before treatment compared with those not having a CL and treated with progesterone. Compared with no response, when a follicle ovulated in response to the first GnRH injection, percentage of cows becoming pregnant after the timed AI increased from 33.3 to 41.6%. Timing of AI at 0 or 24h after the second GnRH injection did not alter pregnancies per AI, but cows having luteal activity before treatment had improved pregnancies per AI compared with noncycling cows. We conclude that identifying noncycling cows by ultrasound was more accurate than by heatmount detectors. Subsequent progesterone treatment of previously cycling cows not having a CL at the onset of Ovsynch increased the proportion of pregnant cows, equal to that of cows having a CL but not treated with progesterone.

Detection of noncyling cows by heatmount detectors and ultrasound before treatment with progesterone (2007)

Our objective was to determine accuracy of identifying anovulatory lactating dairy cows before the application of a timed AI protocol [with or without progesterone supplementation via a controlled internal drug release (CIDR) insert and 2 different timings of AI] by using heatmount detectors and a single ovarian ultrasound examination. At 6 Midwest locations, 1,072 cows were enrolled in a Presynch protocol (2 injections of prostaglandin F2α(PGF2α) 14 days apart) with the second injection administered 14 days before initiating the Ovsynch protocol (injection of gonadotropin releasing hormone (GnRH) 7 days before and 48 hours after PGF2αinjection, with timed AI at 0 or 24 hours after the second GnRH injection). Heatmount detectors were applied to cows at the time of the first Presynch injection, assessed 14 days later at the second Presynch injection and again at initiation of the Ovsynch protocol, and ovaries were examined for presence of a visible corpus luteum (CL) by ultrasound before initiation of treatment. Treatments were assigned to cows based on presence or absence of a visible CL: 1) anovulatory (no CL + CIDR insert for 7 d); 2) anovulatory (no CL + no CIDR); and 3) cycling (CL present). Further, every other cow in the 3 treatments was assigned to be inseminated concurrent with the second GnRH injection of Ovsynch (0 hour) or 24 hours later. Pregnancy was diagnosed at 33 and 61 days after the second GnRH injection. Heatmount detectors and a single ultrasound examination both underestimated proportions of cows classified as anovulatory or having no prior luteal activity compared with those classifications determined by concentrations of progesterone in blood serum. Overall accuracy of heatmount detectors and ultrasound was 71 and 84%, respectively. Application of progesterone to cows without a CL at the time of the first injection of GnRH reduced incidence of ovulation but improved pregnancy rates at day 33 or 61 compared with nontreated cows without a CL at the onset of the Ovsynch protocol. Pregnancy rates and pregnancy survival did not differ for cows having a CL before treatment compared with those not having a CL but treated with progesterone. Pregnancy rates were 1.5-fold greater for cows ovulating in response to the first GnRH injection. Timing of AI at 0 or 24 hours after the second GnRH injection did not alter pregnancy rates, but cows having prior luteal activity before treatment had improved pregnancy rates compared with anovulatory cows. We conclude that identifying anovulatory cows by ultrasound was more accurate than by heatmount detectors. Subsequent treatment of potential anovulatory cows with progesterone failed to improve fertility but had benefit for cows with prior estrous cycles at the onset of the timed AI (TAI) protocol, regardless of luteal status before the final luteolytic injection of PGF2α.; Dairy Day, 2007, Kansas State University, Manhattan, KS, 2007; Dairy Research, 2007 is known as Dairy Day, 2007

219 COMPARISON OF ESTRUS - OVULATION SYNCHRONIZATION TREATMENTS USING HOLSTEIN HEIFERS AS EMBRYO TRANSFER RECIPIENTS

The Ovsynch system (Pursley et al. 1995 Theriogenology 44, 915–923) has been effectively employed as the synchronization method of recipients for embryo transfer (ET) (Nishisouzu et al. 2004 Reprod. Fertil. Dev. 16, 212–213). To establish the most effective Ovsynch system, we experimentally assessed 3 different protocols by comparing resultant estrus-synchronization rates of Holstein heifers and pregnancy rates of the recipients after ET. Holstein heifers averaging 14–15 months old and weighing over 330 kg were used in this study. They were randomly separated into the following 3 groups: (1) Select-synch (SS) group: an intramuscular (IM) injection of 50 �g GnRH analog was given to heifers at a random stage of the estrus cycle, followed 7 days later by 2 IM injections of 7.5 mg PG analog at an interval of 6 h; (2) Co-synch (CS) group: another IM injection of 50 �g GnRH was given to the SS group at 48 h after the first injection of PG; and (3) Heat-synch (HS) group: an IM injection of 0.75 mg estradiol benzoate was given to the SS group at 24 h after the first injection of PG. Estrus detection was evaluated twice daily by visual observation and use of a Heat Mount Detector. All heifers were additionally injected with 1500 IU hCG 5 days after estrus, to ensure favorable luteal function (Nishigai et al. 2001 J. Reprod. Dev. 47, 283–294). Rectal palpation was used to select acceptable recipients, i.e. those having functional corpora lutea (CL) e17 mm in diameter for 7 days after showing estrus (Nishisouzu et al. 2004 Reprod. Fertil. Dev. 16, 212–213). The size of CL e17 mm was determined by rectal palpation by skillful transferors. Fresh embryos collected from super-ovulated cattle 7 days after estrus were nonsurgically transferred only into acceptable recipients that had functional CL and were properly synchronized, 7–8 days after estrus. Final diagnosis of pregnancy was carried out 60 days after ET. Data were analyzed by the chi-square test. The HS group showed significantly higher (P &amp;lt; 0.01) rates of estrus synchronization (87/89: 98%) at 24–72 h after PG injection, estrus detection (98%), and acceptable suitability as recipients with a functional CL (92%) compared to those of the SS (185/210: 88%, 87%, and 73%, respectively) and CS (68/81: 84%, 74%, and 69%, respectively) groups. The pregnancy rates of heifers that received an embryo were not significantly different among HS, SS, and CS groups (45/82: 55%, 78/153: 51%, and 25/56: 45%, respectively). However, because the yield rate of acceptable recipients in the HS group was higher than in the other groups, the final pregnancy rates (no. pregnant/no. synchronization treatment) of the HS group (50%) was significantly higher than those of the SS and CS groups (37%; P &amp;lt; 0.05, and 31%; P &amp;lt; 0.01, respectively). Taken together, these findings demonstrate that the HS protocol is effective for estrus–ovulation synchronization of Holstein heifers, thus improving the productivity of ET by increasing the yield rates of heifers with a functional CL which leads to acceptable pregnancy results.

The effect of timing of administration of oestradiol benzoate on characteristics of oestrus, timing of ovulation and fertility in Bos indicus heifers synchronised with a progesterone releasing intravaginal insert.

To compare the timing of onset of oestrus and ovulation, characteristics of oestrus, and fertility in Bos indicus heifers synchronised with a progesterone releasing intravaginal insert (IVP4) and administration of oestradiol benzoate (ODB) either at the time of removal of the insert or 24 h later. Cohort study. Bos indicus and Bos indicus cross heifers were treated on two farms (Farm A, n = 273; Farm B, n = 47) with an IVP4 for 8 days with 1.0 mg of ODB administered at the time of device insertion and 250 mg of cloprostenol at the time of device removal. Heifers in the ODB-0 group were administered 0.75 mg of ODB at the time of device removal while heifers in the ODB-24 group were administered the same dose of ODB 24 h after device removal. Heifers were inseminated once daily after detection of oestrus. Heifers not detected in oestrus by 72 h after removal of inserts were inseminated at that time. Oestrus was detected in heifers on Farm A using heatmount detectors while on Farm B oestrus in heifers was monitored using radiotelemetry of mounting pressure. Ovarian follicular development was monitored daily in 30 heifers on Farm B from the time of administration of inserts until ovulation to a maximum of 96 h after removal of inserts, and again 11 days after removal of inserts (Day 19). A blood sample was collected from all heifers on Farm B on Day 19 and analysed for plasma concentration of progesterone. Pregnancy was diagnosed 6 to 8 weeks after insemination. Administration of ODB at the time of removal of inserts shortened the time interval to oestrus and ovulation (P < 0.001), increased the number of mounts recorded during oestrus (P = 0.04) and reduced the odds of pregnancy (P = 0.03). The proportion of heifers ovulating on Farm B was 67% and was not affected by treatment group (P = 0.61). The mean diameter of the largest follicle measured in ovaries was greater at the time of removal of inserts (9.1 +/- 0.6 vs 10.7 +/- 0.4; P = 0.03) and at the expected time of the LH surge (8.1 +/- 0.4 vs 11.5 +/- 0.3 mm; P < 0.001) in heifers that ovulated compared to heifers that failed to ovulate, respectively. Emergence of a new follicular wave was not detected during the synchronisation treatment in heifers that failed to ovulate. Concentrations of progesterone in plasma on Day 19 were less in non-pregnant heifers (P = 0.05) compared to heifers subsequently diagnosed as pregnant to insemination and were affected by the diameter of the ovulatory follicle (P = 0.01). Administration of ODB at the time of removal of inserts can shorten the time interval to oestrus and ovulation and can reduce fertility when insemination is carried out once daily. Further work is needed to determine if prolonged suppression of follicular development, anovulatory oestrus and premature ovulation occuring in some heifers is associated with administration of ODB.

Conception Rates in Beef Heifers at Four Time Intervals After Prostaglandin F2α

Two age groups [14 to 15 mo, younger heifers (YH), n = 291; 21 to 22 mo, older heifers (OH), n = 194] of Brangus and Brangus crossbred heifers were used to compare conception rates to AI at 48, 72, 96, or 120h after two injections of prostaglandin F2α (25mg−1 heifer; PGF) given 14 d apart. Estrous detection was not conducted, but a heat mount detector was placed on each heifer at the second PGF injection. Heifers with activated detectors at 48h after a second injection of PGF were artificially inseminated between 0930 and 1100h. This procedure was repeated for heifers with newly activated detectors at 72, 96, and 120h after the second PGF injection. Mean BW was heavier (P<0.01) for OH compared with YH (448 ± 5 and 394 ± 3 kg, respectively). A total of 259 heifers (53.4%) had activated heat mount detectors, and 29, 107, 80, and 43 heifers were inseminated at 48, 72, 96, and 120 h, respectively. Conception rate did not differ between age groups but was affected by interval to insemination (P=0.07; χ2= 7.2; df = 3) in YH. Conception rates in YH were 52.9 and 31.5% at 48 to 72h and 96 to 120 h, respectively (P<0.01; χ2 = 7.4; df = 1). Within age group, mean BW of heifers that conceived did not differ among the four intervals to insemination. Mean BW did not differ between heifers that did or did not conceive. It is concluded that conception rates decline in YH, but not in OH, as the interval to response and subsequent insemination after the second injection of PGF increases.

Detection and Characterization of Estrus in Dairy Cattle with an Electronic Heatmount Detector and an Electronic Activity Tag

The length and onset of estrus was studied in 71 lactating dairy cows using an electronic heatmount sensor (HeatWatch; DDx Inc., Boulder, CO, DeForest, WI) and an electronic activity tag (Heat Seeker, Boumatic, Madison, WI). Three methods were used to determine estrus: 1) the electronic heatmount system, 2) an increased activity ratio algorithm determined by the Heat Seeker, and 3) an increased activity count algorithm calculated for each estrous period. Mounting and physical activity variables were characterized, and the effects of synchrony, parity, and weather on these variables were determined with data from two different trials. Cows in trial 1 were not synchronized, while cows in trial 2 were synchronized. The results of the study were consistent as follows: mean numbers of mounts were 6.70±0.7 and 5.42±0.80 for trials 1 and 2, respectively; each mount lasted 3.20±0.19s (trial 1) and 3.36±0.42s (trial 2). Total mounting activity averaged 5.83±0.78h per estrous period in trial 1 and 5.57±1.02h in trial 2. Estrus identified by the increased activity count algorithm corresponded more closely to standing mount activity (determined by the HeatWatch System) than did the increased activity ratio algorithm. Synchrony, parity, and weather did not have a direct effect on physical activity. Hot weather decreased the duration of standing mount activity significantly, but did not affect the number or duration of individual mounts. All three methods of estrus detection employed improved the efficiency of detection over visual observation.

Oestrus in relation to peak oestradiol levels in ovariectomized Galloway cows

AbstractThe objective of the present study was to characterize the variation in oestrous behaviour among ovariectomized cows in response to a measured dose of oestradiol benzoate (OB) . In study 1, nine ovariectomized Galloway cows, approximately 10 years old, were challenged with an intramuscular injection of either 0·25, 0·5 or 1·0 mg of OB. Following this, 0·5 mg OB was chosen as the appropriate dose required to induce oestrous behaviour in ovariectomized Galloway cows. In study 2, nine cows injected with 0·5 mg OB were monitored for oestrous behaviour using KAMAR® heat mount detectors. Blood samples for plasma oestradiol-17β (E2) assay were taken every 4 h between 0 to 72 h and once at 96 h, following OB administration. The plasma E2 concentrations between 0 to 96 h following OB administration differed significantly ( P &lt; 0·001) among cows. The interval to peak E2 concentrations averaged 17·42 (s.e. 2·21) h and the mean peak E2 concentration was 5·86 (s.e. 0·57) ng/l. The mean interval from OB administration until onset of mounting activity was 24·57 (s.e.2·38) h and the duration of oestrus averaged 10·5 (s.e. 1·99) h . In all cows, mounting activity occurred following peak E2 concentrations after an average interval of 7·73 (s.e. 1·84) h. There was no significant association between peak E2 concentrations and the interval to onset of mounting activity or its duration. Since the variation among Galloway cows in the manifestation of behavioural oestrus was independent of systemic E2 concentrations, it implies that there are inherent differences between individuals in the sensitivity of the hypothalamus to physiological E2 thresholds. This may help to explain the incidence of silent ovulation in some animals and the occurrence of overt oestrus associated with follicular activity during the luteal phase of the cycle or during the various stages of pregnancy, in the presence of high plasma progesterone concentrations.