Marking Harnesses Research Articles

PSX-28 Using estrus detection patches or a ram wearing a marking harness to monitor estrus in synchronized hair sheep ewes

Abstract Determining when a ewe is in estrus is important when using estrous synchronization and artificial insemination in sheep. This study was conducted to compare the efficacy of estrus detection patches (Estrotect™) and rams wearing marking harnesses for monitoring estrus in synchronized hair sheep ewes. St. Croix White (STX) ewes (3.5 ± 0.3 y of age, 89.7 ± 2.2 d post-partum) were synchronized using progesterone releasing inserts (Eazi-Breed™ CIDR) for 12 d. On the day of CIDR removal (d 1) ewes were administered prostaglandin (Lutalyse®; 15 mg i.m.) and placed with fertile STX rams in 0.55 ha pastures. One group of ewes (n =10; MH) was placed with a ram wearing a marking harness and a second group (n = 16; EP) had estrus detection patches placed on their rumps before being placed with a ram without a harness. Estrus detection was conducted using visual observations twice a day through d 7. A ewe was considered to be in estrus when crayon marks were observed on the rump or the patch was activated, based on product guidelines. Cumulative percentage of ewes in estrus was analyzed using the CATMOD procedure with treatment, day and the interaction in the model. All patches stayed in place on the EP ewes through d 7. By d 4 90% of MH ewes and 75% of EP ewes had been observed in estrus (P < 0.05). By d 7 90% of MH ewes and 81.25% of EP ewes had been observed in estrus (P < 0.05). With costs of $1.33 per patch or $29.33 for one harness and crayon the patches may be more economical when dealing with up to 21 ewes per ram. Estrus detection patches can be used on hair sheep ewes to detect estrus just as effectively as a ram with a marking harness.

Optimal dose of PG600 when given to progestogen-synchronized ewes during anestrus as affected by day of the year and temperature.

The objective of this long-term study was to improve the out-of-season breeding rates for ewes by examining effectiveness of dose levels of PG600, a combination of 80-IU/mL pregnant mare serum gonadotropin and 40-IU/mL human chorionic gonadotropin. Each week, during the anestrous season from 1998 through 2016, mature ewes were inserted with 1 of 2 progestogen devices. After 9 to 13 d, at removal of the device, ewes were injected intramuscularly with a specific dose of PG600. A total of 1,402 ewes were treated in this study, with weekly treatment groups ranging from 3 to 12 ewes. Ewes were assigned randomly in equal numbers to 1 of 2 ram pens with one fertile ram in each pen. Rams were fitted with a marking harness. Between 36 and 48 h after removal of the device, rams were switched. Ewes were checked for crayon marks (indicative of estrus) at 36, 48, and 96 h after removal of synchronizing devices. Rams were removed after 1 wk. Pregnancy status was diagnosed at 90 d of gestation using radiography and verified at 120 d or at lambing. To explore the impact of dose level, daylight, and temperature on pregnancy rate, we formulated an ordered multinomial probit model. The model controls statistically for dose level, synchronization device type, device reuse, and natural variation in minimum daily temperature and day of the year (DOY). Predicted pregnancy rate and type of birth at 90 d of gestation were significantly affected by DOY and temperature as well as dose level. Both observed and predicted pregnancy rates were higher for PG600 dose levels between 2.00 and 3.50 mL than for those below 2.00 mL or above 3.99 mL. By giving optimal amounts of PG600 to anestrous ewes, producers will have a greater number of pregnant ewes at lambing during the out-of-season lambing time.

Reproductive responses to sexually active buck of does treated with melatonin when body weight/body condition is increasing or decreasing

When the sexual activity of bucks is minimal, there is a minimal male effect on does regardless of their body weight (BW)/body condition (BC) and whether does are treated with melatonin or not. The study examines whether sexually active bucks can induce an adequate male effect in does with an increasing or decreasing trajectory of change in BW/BC when does are or not treated with melatonin. During natural anoestrus, 46 Blanca Andaluza does were assigned to two groups: 1) low BW/low BC group in which does were fed 1.9 times maintenance requirements for dietary energy for gaining BW/BC (LLg group; n = 23); or 2) a high BW/high BC group in which the does were fed 0.4 times maintenance requirements for dietary energy that resulted in a loss of BW/BC (HHl group; n = 23). There were similar numbers of does in each group that were treated or not treated with melatonin (MEL). Following 48 days of isolation from bucks, four sexually active individuals fitted with marking harnesses were transferred to the paddock containing the does of each group. Blood samples were collected by jugular venipuncture (before the distribution of concentrate) twice per week. The effect of the treatments (increasing or decreasing BW/BC and melatonin) on the different variables that were assessed were analysed using an ANOVA or the Fisher-Freeman-Halton exact probability test as necessary. During the 35 days after treatments were applied, the percentage of females expressing oestrous and having an ovulation were greater in the LLg + MEL than HHl-MEL subgroup (P < 0.05). The interaction of nutrition × melatonin treatment had a significant effect on reproduction of does (P < 0.05). This could be explained by the greater plasma glucose and IGF-1 and lesser plasma non-esterified fatty acid concentrations in does with increasing BW/BC (P < 0.01), and the greater IGF-1 concentrations of MEL-treated females (P < 0.01). The LH concentration and pulsatile release of this hormone from the pituitary were also modified by the presence of the males (P < 0.01). Furthermore, the LLg + MEL-treated does were responsive to the presence of bucks (P < 0.05). The present results indicate sexually active males cannot induce an adequate reproductive response in females with decreasing BW/BC even when does are being treated with melatonin. The presence of bucks enhanced the doe reproductive response when does were treated with melatonin and a pattern of increasing BW/BC.

The reproductive performance of female goats treated with melatonin is not improved after introduction to bucks displaying springtime sexual activity if these does are experiencing decreasing body weight/condition score

The aim of the present work was to determine whether treatment with melatonin modifies the reproductive response of female goats experiencing increasing or decreasing body weight (BW)/body condition score (BCS) when introduced to bucks displaying springtime sexual activity. During natural anoestrus, 53 does were isolated from bucks for a period of 42days and distributed into two groups: 1) low BW/low BCS animals (N=24) (LLg group), which were fed 1.9 times their maintenance requirements so they would experience increasing BW and BCS; and 2) high BW/high BCS animals (N=29) (HHl group), which were fed 0.4 times their maintenance requirements so they would experience decreasing BW and BCS. Half of each group was treated, or not, with melatonin (LLg+Mel N=12, HHl+Mel N=15, LLg-Mel N=12 and HHl-Mel N=14). On 6th May they were introduced to six males, showing natural sexual activity, fitted with marking harnesses (thus permitting the detection of oestrous activity). The ovulation rate was assessed by transrectal ultrasonography and confirmed via the plasma progesterone concentration (measured twice per week in blood samples). Plasma glucose, IGF-1 and non-esterified fatty acid concentrations were also determined, along with the conception rate, fertility, prolificacy and productivity of the does. LH concentrations and LH pulsatility were also recorded in the hours around introduction to the males. 'Oestrous plus ovulation' was observed only in does treated with melatonin. A higher conception rate and greater fertility and productivity were observed among the LLg+Mel does. These females showed higher glucose and IGF-1 concentrations after the introduction of the males. LH concentrations increased after male introduction independent of all other conditions. In conclusion, the present results show that treatment with melatonin does not enhance reproductive performance in does experiencing decreasing BW/BCS, but can improve it when does are experiencing increasing BW/body fat reserves - even when exposed to males displaying only springtime sexual activity. This might be explained by the higher blood glucose and IGF-1 concentrations of the LLg+Mel females.

Reproductive performance of Lacaune dairy sheep exposed to artificial long days followed by natural photoperiod without and with additional progestagen treatment during the nonbreeding season

This study compared the reproductive performance of Lacaune dairy ewes exposed to a light program and subsequent male introduction without (n=36) or with (n=36) an additional 6-day progestagen treatment during the nonbreeding season. All ewes were exposed to extended day length (16hours light and 8hours darkness) for 77days during winter (December 15 until March 2) followed by increasing natural photoperiod. At the end of the photoperiodic treatment, three blood samples were collected 6days apart for progesterone (P4) analysis to determine cyclic activity. One half of the ewes were additionally subjected to a 6-day progestagen treatment in combination with PGF2α and eCG at insert withdrawal. Rams fitted with marking harnesses were introduced to females for 45days and marked ewes recorded. Ewes exposed to the light program only were joined 40days after the end of photoperiodic treatment, and ewes with additional progestagen treatment were joined 1day after insert removal (40-44days after the end of photostimulation). Lambing data were recorded and fertility (percentage of ewes lambing, lambing rate, and litter size) assessed to the first service period and overall. Mean serum P4 concentrations were similarly (P>0.05) low in both groups (0.4-0.7ng/mL vs. 0.4-0.6ng/mL). On the basis of elevated P4 levels (>1ng/mL), evidence of luteal activity was found in 27.8% of the ewes at the end of the light program. Estrus response was equally high (97.2%) and estrus distribution highly synchronized in progestagen-treated ewes (91.7% within 4days). In ewes exposed to the light program only, estrous activity was recorded within 4days (six ewes), from Day 8 to Day 17 (17 ewes) and from Day 19 to Day 25 (12 ewes) after joining. The percentage of ewes that lambed to the first service period was higher (P<0.05) in ewes exposed to the light program only than that in the group additionally treated with progestagen/PGF2α/eCG (94.4% vs. 69.4%). Overall, the percentage of lambing ewes was similar in both groups (97.2% and 94.4%), and lambing rates (1.4-1.9) and litter sizes (1.9-2.1) were high and not influenced (P>0.05) by the treatment. In conclusion, this study reports that exposition of Lacaune ewes to artificial long days followed by natural day length and male introduction is highly effective to induce fertile estrous activity during the nonbreeding season and offers a reliable and practical alternative to hormonal manipulation for out-of-season breeding in sheep.

Body condition score is a critical factor determining the onset of puberty in Blanca Andaluza female goat kids

This study examines the effect of body condition score (BCS), independently of bodyweight (BW), on the onset of puberty in Blanca Andaluza female kids born in Autumn (November). Thirty-six female kids were distributed into three groups according to their BW and BCS: low BW and low BCS (LL, n = 10), low BW and high BCS (LH, n = 10), and high BW and high BCS (HH, n = 16). Feeding was adjusted weekly so that the animals would gain ~50 g per day. Oestrus was checked daily using young vasectomised bucks fitted with a marking harness. The ovulation rate was determined by transrectal ultrasonography 10 days after the identification of oestrus. Plasma samples were obtained weekly for progesterone determination. Changes in BW and BCS were also recorded weekly. The BCS had a clear effect on the date of first ovarian activity and first detected oestrus. The HH kids experienced the earliest onset of puberty (31 August ± 2.4 days) although no significant difference was seen compared with the LH group (19 September ± 8.7 days). A significant difference was recorded, however, in comparison with the LL group (25 October ± 7.8 days) (P &lt; 0.001). No effect of BCS was observed on ovulation rate. These results show that, in Blanca Andaluza female kids, the onset of puberty depends strongly upon BCS. There may be clear benefit in breeding November-born animals if, during the prepubertal period, they can be maintained with a high BCS.

Efficacy of various five-day estrous synchronization protocols in sheep

Abstract The objective of this study was to determine the effects of ewe estrus synchronization protocols including combinations of controlled internal drug releasing ( CIDR ) inserts for 5 d, GnRH, and PG on concentrations of progesterone ( P4 ) and reproductive performance of ewes during different breeding seasons. Experiment 1 was conducted during the transition season (August–October) and Experiment 2 was conducted during the anestrous season (April–May). In both experiments ewes received 1 of 4 treatments: (1) untreated ( CON ); (2) CIDR (0.3 g P4) insert ( CT ); (3) CIDR and PG at CIDR removal ( CTP ); or (4) GnRH at CIDR insertion and PG at CIDR removal ( CTG ). Rams equipped with marking harnesses were introduced at CIDR removal (d 0) and ewes were observed for breeding marks twice daily at 0800 h and 1700 h. In Experiment 1, days to estrus was greater ( P ≤ 0.01) in CON (9.5 ± 1.10 d) and CTP (6.5 ± 1.04 d) compared with CT (3.6 ± 1.03 d). No differences ( P = 0.27) were detected in pregnancy rate within the first 17 d of the breeding season for CON, CT, CTP, and CTG treatments (37 ± 7.8%, 62 ± 7.5%, 56 ± 8.1%, and 46 ± 7.7%, respectively). Similarly, no differences ( P ≥ 0.28) were detected among treatments for lambing rate and prolificacy. Contrasts for all CIDR treatments compared to controls determined that CIDR treated ewes had less days to estrus and lambing ( P ≤ 0.05) than control ewes. In Experiment 2, days to estrus was greater ( P ≤ 0.02) in CON (6.5 ± 1.05 d) and CTP (5.9 ± 0.88 d) compared with CTG (3.0 ± 0.88 d). No differences were detected ( P ≥ 0.23) among treatments for overall percentage of ewes exhibiting estrus. No differences ( P = 0.79) in pregnancy rate within the first 17 d of the breeding season were detected among treatments (42 ± 12.4%, 37 ± 11.3%, 35 ± 11.1%, and 50 ± 10.9% for CON, CT, CTP, and CTG, respectively). No differences ( P ≥ 0.44) were observed among treatments in overall lambing rate and prolificacy. In conclusion, inserting a CIDR for 5 d prior to ram introduction regardless of the use of PG or GnRH, reduced the interval to estrus compared with untreated ewes but did not impact overall pregnancy rates, lambing rates, or prolificacy.

Comparison of 6-day progestagen treatment with Chronogest® CR and Eazi-breed™ CIDR® G intravaginal inserts for estrus synchronization in cyclic ewes

The aim of this study was to compare the efficacy of two different short-term progestagen treatments for estrus synchronization in cyclic ewes. A total of 292 ewes of 3 flocks (A–C) on different farms were treated for 6 days with Eazi-breedTM CIDR® G (n = 145) or Chronogest® CR (n = 147) vaginal inserts in combination with 0.125 mg Cloprostenol and 300IU eCG at device removal. Blood samples were taken for progesterone (P4) determination at insert application and removal as well as 14 days later. One day after insert removal rams fitted with marking harnesses were joined to ewes for 35 days and marked ewes recorded daily. Lambing data were recorded and fertility to first service period and overall assessed. Results show that 24–96 h after insert removal 98.8% and 89.4% of the synchronized ewes in the flocks B and C were in estrus. Estrus response was not affected by the type of progestagen treatment and was lower (P < 0.05) in nulli- (82.1%) than in pluriparous (97.5%) ewes. Type of progestagen treatment did not affect fertility, but flock and parity influenced the percentage of ewes that lambed as well as the lambing rate. Overall more ewes (P < 0.001) lambed in flock A compared to flocks B and C (93.0 vs. 72.5 and 59.1%). In nulliparous animals the percentage of ewes that lambed was higher to the first service (P < 0.05) period but lower (P < 0.001) to the overall service period compared to pluriparous animals (51.5% vs. 49.3% and 64.7% vs. 84.2%). Lambing rates were higher in flock A than in flocks B and C to first service period and overall (1.3 ± 1.4, 0.9 ± 1.0, and 0.7 ± 1.0, P < 0.01 and 1.9 ± 1.1, 1.3 ± 0.9, and 1.0 ± 1.0, P < 0.001) and in nulliparous overall lower than in pluriparous ewes (1.1 ± 1.1 and 1.6 ± 1.1, P < 0.01). Serum P4 concentrations measured 14 days after insert removal were higher in the Chronogest® CR than in the Eazi-breedTM CIDR® G group (6.8 ± 4.1 ng/mL vs. 5.7 ± 3.3 ng/mL). Ewes of flock A had higher P4 values compared to ewes of flocks B and C (8.3 ± 4.1 ng/mL vs. 4.5 ± 1.5 ng/mL and 3.8 ± 1.7 ng/mL) and nulliparous lower P4 concentrations than pluriparous ewes (4.5 ± 2.2 ng/mL vs. 6.7 ± 4.0 ng/mL). In conclusion, a 6-day treatment with Chronogest® CR and Eazi-breedTM CIDR® G with prostaglandin and eCG at insert removal resulted in high estrus response and similar fertility in cyclic ewes. © 2012 Elsevier B.V. All rights reserved.

Enhancement of the male effect on reproductive performance in female Mediterranean goats with long day and/or melatonin treatment

The aim of this study was to determine whether the male effect on reproductive performance in female Mediterranean goats could be enhanced if used in combination with long day and/or melatonin treatments. Thirty-two does were exposed to long days (16 h of light/day) for 95 days. At the end of this period, 16 received one melatonin implant (group LD-M) and 16 did not (group LD). Simultaneously, 16 does under natural photoperiod were implanted with melatonin (group M) or given no treatment (group C, n=16). On April 14th, after 49 days of isolation from males, all does were exposed to bucks fitted with marking harnesses. Oestrous activity, as detected by visual observation, was recorded daily. Transrectal ultrasonography was used to record ovulation, and ovarian activity confirmed by determining plasma progesterone concentration. Oestrous activity, ovulation and fertility were greater in all treatment groups compared with group C (P<0.05), but no differences in ovulation rate or litter size were observed (P>0.05). Productivity (mean number of kids per female) of the LD-M and M groups was significantly greater than in group C (1.50 ± 0.01 and 1.37 ± 0.01 vs. 0.69 ± 0.01 kids, respectively) (P<0.05). Combining melatonin treatment with natural or artificial long days adds to the impact of the male effect.

Patterns of estrous cycles, estrous behavior, and circulating prolactin in spring and summer in ewes selected for autumn lambing and exposed to ambient or long-day photoperiods

Estrous behavior in response to ambient and long-day photoperiods was evaluated in ewes developed by 10 years of selection for ability to lamb in autumn. Following October lambing, 67 ewes were moved indoors and exposed to long-day (16L:8D) or ambient photoperiods from February 2 until July 6. Two vasectomized rams with marking harnesses were housed with each group. Estrous behavior was monitored twice weekly. Ewes from the selection line were unresponsive to long days, with no effects on estrous behavior, frequency of ovulation, or circulating prolactin. Adult ewes were anestrus for only 34±3 d, but 2- and 3-years-old ewes were anestrus for 72±7 and 57±10 d, respectively. Frequencies of ovulation based on circulating progesterone concentrations in March, May, and June were 97%, 95% and 52%, respectively, indicating that many ewes that did not exhibit estrus still ovulated. Prolactin concentrations increased from 10 ng/ml in February to 27 ng/ml in March and 173 ng/ml in June but were not affected by light treatment. Ten ewes that failed to exhibit estrus behavior for at most 24 d during the main study were then monitored for 74 additional long days. Nine of 10 ewes did not exhibit estrus for periods similar to 1 or 2 estrus cycles during this period, but eight ewes re-initiated cycles by the end of the study on September 18. Selection for ability to lamb in autumn thus resulted in ewes with an abbreviated seasonal anestrus and reduced sensitivity to long days.

Effect of porcine zonae pellucidae immunisation on ovarian follicular development and endocrine function in domestic ewes (Ovis aries)

Domestic ewes (Ovis aries) were immunised with porcine zonae pellucidae (pZP) or pZP conjugated to keyhole limpet haemocyanin (KLH) in adjuvant(s) to examine the feasibility of the species to serve as a model for further development of pZP-based vaccines in ungulates. Two immunisation groups were employed, with a third group receiving only adjuvant (n = 5 per group). Early in the study, oestrous activity was monitored by the use of a vasectomised ram fitted with a marking harness. Eventually, ewes were exposed to an intact ram for breeding. In addition, weekly serum and every-other-day faecal samples were collected to measure pZP antibodies and progesterone metabolite concentrations respectively. At the conclusion of the study, fecundity was established, and ovarian tissue was examined. Ewes immunised against pZP : KLH with adjuvant produced minimal antibody absorbance levels, displayed normal oestrous cycles, became pregnant upon introduction of the intact ram and exhibited normal ovarian histopathology. Ewes immunised against pZP with adjuvant produced high antibody absorbance levels, were acyclic following primary immunisation and were infertile. Examination of the ovarian tissue revealed atrophic changes that included: (1) the absence of growing follicles; (2) significant reduction in the number of primordial follicles; and (3) the presence of abnormal granulosa cell clusters lacking oocytes. Antisera displayed immunoreactivity to the major components of pZP, and immunohistochemical labelling of ovarian tissue showed specificity to the ZP. These data are the first generated in an ungulate species showing deleterious effects of pZP immunisation on folliculogenesis and oestrous cyclicity.

Effect of melengestrol acetate (MGA) treatment or temporary kid removal on reproductive efficiency in meat goats

The use of melengestrol acetate (MGA; Summer) or temporary kid removal (4 weeks postpartum; Fall) for inducing/synchronizing estrus was evaluated in goats. In the first trial, 47 does were group-fed a commercial diet to provide 0.25 mg MGA/doe daily (n = 25) or a control diet (n = 22) for a period of 10 days. Twenty-five of the does lambing in the fall from this experiment were used in a second experiment. Beginning on day 28.1 ± 0.8 of lactation, kids from 13 does (kid removal) were removed from their dams for 2 days while kids from the remaining 12 does (control) remained with the dams. Mature bucks wearing marking harnesses were introduced for mating at the end of MGA treatment (Experiment 1) or at the time of kid removal (Experiment 2). Does fed MGA were mated approximately 2.1 days earlier (P < 0.05) than control does. The percentage of does mated (84% versus 100%), pregnancy rate (58% versus 90%), and kidding rate (58% versus 90%) was lower (P < 0.05) for the MGA-treated versus the control does, respectively. In Experiment 2, does with kids removed were mated approximately 1.3 days earlier than the control does, but the mean weaning weight of the kids (11.0 ± 0.4 kg for both treatments) was not influenced by treatment. The mean pregnancy rate, kidding rate, kid birth weight, or kid weaning weight was not influenced by treatment and averaged 73.0 and 79.0%, 3.3 ± 0.2 and 16.8 ± 0.7 kg for both treatments, respectively. Overall, although not necessary for mating, a decreased time to first mating and increased synchrony of estrus followed both MGA treatment or temporary kid removal. This may be implemented if improved estrus synchrony is desired. However, more research is needed to overcome the decreased fertility recorded following MGA use.

193 EVALUATION OF A NOVEL ELECTRONIC ESTRUS DETECTION DEVICE IN RECIPIENTS SYNCHRONIZED FOR EMBRYO TRANSFER

The ability to detect estrus in cattle is an important aspect for both successful artificial insemination (AI) and successful embryo transfer (ET). The use of estrus detection devices has allowed producers to more precisely determine when to breed their cattle. There have been many types of devices including chin-ball marking harnesses, dye patches, and even electronic devices that monitor the animal's activity. With the growing popularity in timed AI and ET, these devices have again become of great interest. The latest tool for estrus detection is the multi-use TattleTale" Heat Detector (Microdyne Co., LLC., St. Joseph, MO, USA). The TattleTale" is an electronic device that is placed in a patch and affixed to the tail head. It is activated by a 3-s mount with subsequent mounts recorded per h through 12 h. Twelve hours after activation the device flashes indicating that the animal is ready for breeding. Such devices may allow breeders to determine exactly when estrus began as well as identify the peak estrus period, resulting in more accurate determination of optimal time for AI or ET. The objective of this study was to compare the accuracy of estrus detection devices when analyzing detection records and pregnancy rates. Cows from the Dixon Springs Agricultural Center (Simpson, IL, USA) were randomly separated into two groups based on estrus detection devices, one group receiving Kamar� patches (Kamor, Inc., Steamboat Springs, CO, USA) and the other receiving TattleTales. Both groups were synchronized using the OvSynch protocol (Syntex, Buenos Aires, Argentina). Cows were checked twice each day for four consecutive days, with a fifth day occurring a week later when the embryos were transferred. Estrus results were analyzed using a PROC UNIVARITE and GLM analyses with differences between treatment means determined by the LSD method of SAS (SAS Institute, Inc., Cary, NC, USA). The TattleTale detected a higher percentage (P &lt; 0.05) of the cows in estrus (92 vs. 70%) than the Kamar� patch. Further, the TattleTale detected more asynchronous recipients (in estrus &gt;48 h before expected) and synchronous recipients (in estrus &lt;24 h than expected), although not significant with this sample size. In the present study, the TattleTale was more accurate in detecting estrus (i.e. fewer pregnancies were observed without estrus detected). Using the TattleTale information, a breeder would be able detect more animals in estrus and determine the most accurate time to breed or transfer embryos. Practically, the use of estrus detection devices in combination with timed AI and ET could allow for the exclusion of animals not in estrus in the optimal time windows for AI or ET, thus saving valuable semen and embryos that would be otherwise wasted on asynchronous females. The advantages of this device to producers include improved pregnancy rates based on timed breeding, lower herd management costs due to reduced quantities of wasted semen or embryos and fewer cows being resynchronized. This device also records any mounting activity missed by visual observation alone. This work was supported by USDA RRF W-1171.

Artificial insemination following observational versus electronic methods of estrus detection in red deer hinds (Cervus elephus)

The objectives were to determine the efficacy of the HeatWatch (HW) electronic estrus detection system for monitoring behavioral estrus (including duration and intensity) in red deer hinds and to evaluate pregnancy rate to AI after detected estrus. Red deer hinds (Cervus elephus; n = 50) were allocated into two treatment groups: AI following synchronization (CIDR/PMSG) and observed estrus (induced estrus group: IE; n = 25) or AI following the detection of natural estrus (NE; n = 25) without hormonal treatment. Hinds were fitted with two HeatWatch (HW) electronic estrus detection transmitters, one above the tail (bottom) and one between the tuber coxae of the pelvic girdle (top), and visual observations for mounting activity began with the aid of young sterile red deer stags (18 months old) fitted with marking harnesses. Hinds in both groups were inseminated (10-12h after observed estrus) with frozen-thawed red deer semen using a transvaginal/cervical AI approach. Following a 26-day period of AI, hinds were placed with a mature fertile stag for an additional 30-day natural breeding period. Pregnancy diagnosis was performed 57 and 86 days after the start of AI. While the hinds were housed with the young stags, 82% were detected in estrus by visual appraisal of stag crayon marks, but only 32% of these were detected by HW. In contrast, in the hinds housed with the mature stag, 93% detected in estrus by crayon marks were also detected by HW. The top HW transmitter consistently recorded more mounts (P < 0.05) than the bottom transmitter. The pregnancy rate was numerically better in IE versus NE hinds (42% versus 29%, P > 0.10). In summary, there were no differences (P > 0.10) in the intensity (number) or duration of mounts (detected by HW) during estrus in IE versus NE hinds, and HW was most effective in detecting estrus in the presence of a heavier, mature stag versus a younger stag. When used in combination with transvaginal AI, an overall first-service pregnancy rate of 36.6% was achieved with AI of frozen-thawed semen in red deer hinds following detected estrus.

The Effect of Dietary Fat Inclusion on Nutrient Intake and Reproductive Performance in Postpartum Awassi Ewes

The objective of this study was to evaluate the effect of dietary fat inclusion on nutrient intake, body weight, milk production, return to estrus, pregnancy and lambing of winter-lambing, postpartum Awassi ewes. Thirty multiparous, winter-lambing Awassi ewes (body weight=51′7.0 kg) were randomly assigned to three dietary treatments (n=10) for 62 days using a completely randomized design. Experimental diets were isonitrogenous, and were formulated to contain 0 (CON), 2.5 (MF), and 5% (HF) added fat, and 33% of the dietary crude protein (CP) as undegradable intake protein (UIP). On day 26 postpartum (day 0=parturition), ewes and their lambs were housed in individual pens for 28 days. Feed offered and refused was recorded daily. At the end of this period, ewes and their lambs within each treatment were combined into one group and fed their respective diet ad libitum. One fertile Awassi ram fitted with a marking harness was allowed with each group for 34 days. No significant (p>0.05) differences in dry matter intake, organic matter intake, and crude protein intake were observed for ewes fed the three experimental diets. No difference was observed in metabolizable energy intake (MEI) for ewes fed the CON and the MF diets (average 8.3 Mcal/d) diet. However, ewes fed the HF diet had greater (p<0.05) MEI compared with the rest of the treatments. Ewe body weights increased throughout the study, unaffected by the experimental diets. No significant differences in milk production were found among ewes fed the three experimental diets. No significant differences were observed in pregnancy rate (6/10, 5/10, 6/10 for CON, MF and HF diets, respectively), lambing rate and the number of lambs per ewe among the three treatments. These results indicate that fat inclusion to high concentrate diets does not improve postpartum reproductive performance of well-fed, winter-lambing Awassi ewes.

Detection of fetal twins in sheep using a radioimmunoassay for pregnancy-specific protein B.

Ovine pregnancy-specific protein B (oPSPB) was isolated from sheep placentas. Antiserum to oPSPB was developed in rabbits. A quantitative RIA was developed and used to assay the serum concentrations of oPSPB during and after pregnancy in ewes bearing single or twin fetuses. Suffolk and Panama ewes, kept with rams equipped with a marking harness, were checked daily for breeding marks as an indication of estrus and bled daily between 10 and 30 d after marking. Ovine PSPB became detectable at 19.7 +/- .14 (mean +/- SE) d after breeding and increased steadily to d 30. Panama oPSPB concentration increased at a greater rate than that of Suffolks (breed x day interaction, P < .01). Ten ewes were bled twice weekly 3 wk before their expected date of lambing and weekly for 7 wk postpartum. Serum concentrations differed considerably between prepartum ewes, but concentrations remained stable within the period of 20 d prepartum. Following parturition, oPSPB concentrations dropped rapidly. In nine ewes, oPSPB was last detectable at 12.78 +/- 2.26 (mean +/- SE) d postpartum. In the 10th ewe, oPSPB was .65 ng/mL at the last sample on d 46 postpartum. To determine the effect of fetal number on oPSPB concentrations, ewes in which estrus was synchronized were bled at d 18, 25, 38, 60, 90, and 120 after breeding. Ewes were killed at d 60, 90, 120, and 148 and fetal number determined. There was a significant (P < .01) difference in the log of oPSPB concentrations according to number of fetuses, day postbreeding, and the day x fetal number interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of selection for growth traits on age and weight at puberty in bovine females.

This 20-yr study, using 584 beef heifers born in the spring of 1984 or 1985, was conducted to determine whether selection for growth traits affected age and weight at puberty. Heifers were from three Hereford lines selected for weaning weight, final weight, and final weight plus muscling score, a control line and a line of Angus cattle. In addition, heifers from reciprocal crosses among the selection lines, control and Angus groups were evaluated. Intact bulls and androgenized heifers fitted with marking harnesses were used to aid in detection of estrus for heifers born in 1984 and 1985, respectively. The time of puberty was identified by the first behavioral estrus. During both years, heifers were weighed at 56-d intervals; these weights were used to calculate weight at puberty. Mean age at puberty was determined using survival analysis; percentages of heifers that were pubertal by the end of the study were transformed to logits for analysis. Heifers born in 1985 were heavier (P less than .05) at puberty than those born in 1984. Heifers in lines selected for growth traits were younger at puberty (P less than .05; 20 d) than were heifers in the control line because of combined direct and maternal genetic effects. Heifers from the final weight, control (P less than .05) and weaning weight lines (P less than .10) weighed less at puberty than Angus heifers; selection line x Angus crossbred heifers were heavier at puberty (P less than .05) than their respective pureline or purebred contemporaries due to heterotic effects. Selection for weaning weight, final weight or final weight plus muscling score did not have a detrimental effect on age at puberty in heifers.

Characterization of secretion of thymosin alpha 1 and thymosin beta 4 during prepuberty, estrus and pregnancy in the bovine female

The objective of the present study was to characterize secretion of thymosin alpha 1 (A1) and thymosin beta 4 (B4) during different stages of ovarian function and pregnancy in bovine females. One hundred and thirty-five prepubertal heifers averaging 9 mo of age at the time the study was initiated were used. Estrous detection was conducted twice daily using intact bulls fitted with marking harnesses. Blood samples were collected at first behavioral estrus and at the time of rectal palpation for pregnancy. Heifers were weighed at the beginning of the study and every 56 days and additional blood samples were collected at those times. Plasma was harvested and radioimmunoassays were conducted to quantify concentrations of thymosin A1 and B4. Mean concentrations of thymosin A1 and thymosin B4 were determined during prepuberty, estrus during which conception did not occur, estrus during which conception did occur, pregnancy and in heifers that failed to attain puberty. Mean plasma concentrations of thymosin A1 and B4 were greater at estrus during which conception occurred than at any other period (P less than .01). Regressions of days prepubertal and days post conception on thymosin A1 and B4 were analyzed. During the 100 days prior to puberty, thymosin A1 and B4 did not change in the heifers that ultimately conceived. However, in the heifers that were never determined to be pregnant by rectal palpation, concentrations of both thymosin A1 and B4 increased linearly during prepuberty (P less than .01). A decline in thymosin A1 and B4 concentrations occurred in a quadratic fashion from conception through the first 100 d of pregnancy (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of an androgenized mare as an aid in detection of estrus in mares

A study was conducted over a 2-mo period to compare estrus detection results obtained using an androgenized teaser mare with those obtained with a stallion, using the same group of 10 normally cyclic mares. The teaser mare was androgenized by administration of boldenone undecylenate (500 mg i.m. every 1 to 2 wk), and allowed to run loose with the mare group. Estrus was determined by observation of the group for a 30-min period daily. In the second month of the experiment, a marking harness was used on the androgenized mare to help detect mares mounted when in estrus. Estrous periods detected by each teasing method were 1) first month: stallion, 18; androgenized mare, 5; 2) second month: stallion, 16; androgenized mare, 9. There were no estrous periods detected by the androgenized mare that were not also detected by the stallion. Under these conditions, the androgenized mare was not an adequate estrus detection aid. Also discussed are the successful results of an independent trial on a breeding farm using an androgenized mare as an estrus detection aid.

Effects of pinealectomy, oestradiol and melatonin on plasma prolactin and LH secretion in ovariectomized sheep.

The study examines whether the pineal gland mediates in the seasonal rhythm in the response of the hypothalamo-pituitary axis to oestrogen in the sheep. Five groups of ewes, each comprised of five sham-pinealectomized ewes and five pinealectomized ewes, were maintained under field conditions over a 2-year period. Group I ewes were ovariectomized and treated with two oestradiol capsules in the first year and one oestradiol capsule in the second year; group 2 ewes were ovariectomized and treated with two oestradiol capsules and three melatonin sachets in the first year and one oestradiol capsule and three melatonin sachets in the second year; group 3 ewes were ovariectomized and treated with three melatonin sachets in the first year and one oestradiol capsule in the second year; group 4 ewes were ovariectomized and treated with empty implants; group 5 had intact ovaries. Blood samples were taken at weekly intervals for determination of plasma prolactin, LH and FSH levels. Cyclic ovarian activity, determined by rams fitted with a marking harness, occurred in both sham-pinealectomized and pinealectomized ewes in group 5 during December to May in both years. A circannual rhythm in plasma prolactin levels was apparent in all ten groups of animals. The levels were highest in spring (September to November) and decreased before the onset of breeding activity in midsummer (December). Ovariectomized ewes with intact pineal glands and treated with oestradiol capsules (group 1) exhibited marked changes in LH and FSH concentrations during the study.(ABSTRACT TRUNCATED AT 250 WORDS)