Reproductive seasonality of hair rams under tropical conditions: an alternative for non-seasonal lamb production?

Reproductive seasonality limits the periods of breeding on the year and, therefore, productive output. However, some breeds appear as probably non-seasonal. The aim of the study was to characterize the seasonal pattern of Santa Inês rams, including an ultrasound characterization of the reproductive tract, testosterone concentrations, and semen characteristics. Fifteen Santa Inês rams remained in a grazing system with concentrate supplementation, and measurements of the reproductive tract and ultrasound evaluation (biometrics and pixel intensity) of the testicles and accessory sex glands were monthly recorded. Computerized seminal evaluations were also performed monthly, and serum testosterone concentration was measured every 15 days. Body weight and condition remained stable throughout the year. In general, reproductive traits varied along the year and reached maximum values during autumn and minimum in spring. Despite that, as fresh semen remained with enough quality to breed all along the year, seasonality does not appear as a limiting factor to breed along the year. Therefore, Santa Inês rams can be used for all-year-round breeding or for crossbreeding when rams from other breeds decrease their fertilizing ability.

Recent advances in treatments for resynchronization of ovulation in small ruminants: a review.

Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.

Ultrasound Diagnosis in Small Ruminants: Occurrence and Description of Genital Pathologies.

This study reports the occurrence and appearance of various reproductive tract pathologies of small ruminants diagnosed using ultrasound. An eight-year retrospective study of collected ultrasound data was carried out in Rio de Janeiro State, Brazil from September 2012 to July 2020. A total of 3463 animals from 16 sheep flocks and 10 dairy goat flocks, raised under extensive and intensive management systems, respectively, were used in the study. All animals were submitted to an ultrasound examination of their reproductive tract. Data were analyzed using Fisher's exact test (p < 0.05), to compare disorder frequencies within and between species. Ewes (4.14%) had fewer reproductive disorders than does (8.98%), while rams (43.63%) and bucks (56.25%) presented no significant differences. Hydrometra was the most frequent finding in does, represented by 50.98% of cases; while, in ewes, recent fetal loss (22.85%) and cystic endometrial hyperplasia (20.00%) were the most frequent. In bucks, the findings showed no clear differences; while, for rams, the most frequent finding was testicular microlithiasis (75.00%). Ultrasonography offers clinically useful information about the reproductive tract via the images it provides; knowledge of which makes it possible to improve the diagnosis, therapy, and prognosis of genital pathologies.

Influence of eCG and reproductive management in the resynchronization of ovulation in dairy goats.

Resynchronization protocols have been proposed as a way of shortening females' unproductive time in the flock, with good results in cattle and sheep. In goats, initial studies have shown that a second progestogen device inserted before luteolysis and pregnancy diagnosis does not interfere with the corpus luteum lifespan or functionality. This study aimed to evaluate the follicular growth, ovulation pattern and pregnancy rate after insertion of a second and new progestogen device for resynchronizing, with or without equine Chorionic Gonadotrophin (eCG), submitted to natural mating (NM) or artificial insemination (AI) to propose a viable resynchronization protocol for dairy goats. A total of 38 multiparous Saanen goats underwent a short-term progesterone protocol [six days exposed to medroxyprogesterone acetate (MAP) intravaginal sponges + 200 IU eCG and 0.12 mg of cloprostenol sodium on the 5th day + 0.025 mg of lecirelin 34 hours after sponge withdrawal] and, on day 16th after the ovulation, received a new MAP device which was retained until day 21. At this moment females were split into four groups: GeCG+NM - 100 IU eCG with NM; GSal+NM - saline solution with NM; GeCG+AI - 100 IU eCG with AI; and GSal+AI - saline solution with AI. Ultrasound scans were performed every 12 h from sponge withdrawal (day 21) until 108 h after sponge withdrawal (day 25) for follicular dynamics evaluation, at 240 h (day 31) for assessing the presence of active corpus luteum, and on day 60 for pregnancy diagnosis. No differences were found regarding ovulation time, synchronization and follicle size. However, GeCG+NM presented a greater estrus manifestation rate (100%) and pregnancy rate (62.5%) when compared to GSal+AI. In conclusion, resynchronization protocols in dairy goats may present satisfactory results.

Biostimulation with the ram effect increases the follicle recruitment, ovulatory diameter, and embryo viability rate in superovulated ewes.

The aim of this study was to compare the preovulatory follicular development and superovulatory outcomes in superovulated ewes which were either stimulated or not stimulated by placement with rams. The treatment regimen to super-stimulate ovarian follicular development was imposed to 28 ewes on "Day 0", from which 14 were stimulated with active rams for 48 h, starting at the time of the fifth FSH dose, with the ram being removed from the pen with the ewes and replaced which other ram every 12 h, using four different rams (group GRE). The other 14 ewes remained isolated from rams throughout the protocol (group GCON). All ewes were administered 133 mg of FSH, into six doses in decreasing quantities, every 12 h. The follicular development and number of ovulations were determined using ultrasonography. Biostimulation resulted in an increased number of large follicles, follicle diameter, and embryo viability rate (viable embryos/recovered structures∗100) was greater in ewes of the GRE than GCON group. The number of corpora lutea, follicular cysts, recovered structures, viable embryos, and degenerated and unfertilized structures was similar in ewes of the GRE and GCON group. Structures were recovered from more GRE than GCON ewes. In conclusion, biostimulation with rams during the last phase of the treatment regimen to induce superovulation enhanced the follicular growth and increased the embryo viability rate in ewes.

Hormonal protocol used for cervical dilation in ewes does not affect morphological embryo quality but reduces recovery rate and temporarily alters gene expression.

BACKGROUND: Information on the impact of hormonal protocols for cervical dilation on the quality of ovine embryos is scarce. METHODS: To compare the quality of embryos after cervical dilation protocol, ewes (n = 64) were allocated into either a treated group (100 µg estradiol benzoate intravenous and 0.12 mg cloprostenol intramuscularly, 12 hours before embryo collection plus 100 iu oxytocin intravenous 15 minutes before the collection procedure) or a control group (saline). Luteal function was analysed using ultrasonography and P4 measurement. Some collected embryos were frozen/thawed for gene expression, others were cultured in vitro, frozen/thawed for gene expression, and the remaining embryos were fixed for the apoptosis test (TUNEL test). RESULTS: The treatment reduced fluid (p=0.04) and structure (p=0.03) recovery rates, but the morphological quality, development stage, and apoptosis incidence of the embryos were not affected by treatment. The corpora lutea of the control group had greater blood perfusion (p = 0.002) and greater P4 concentrations at 6, 9, and 12 h after the treatment (p < 0.0001). The expression of BAX, BCL2, PRDX1, and HSP90 genes were not affected by the treatment. However, the embryos in the treated group had fewer NANOG and OCT4 transcripts than control embryos (p = 0.008; p = 0.006, respectively). After culture, there was no difference between the groups in any gene. CONCLUSION: The hormonal protocol for cervical dilation reduced the efficiency of embryo collection. In addition, the treatment induced luteolysis and a transient alteration of embryo gene expression, however there were no detectable changes in embryo morphological quality, development stage, or incidence of apoptosis.

Early resynchronization protocols for goats: Progestogens can be used prior to an early pregnancy diagnosis without affecting corpus luteum functionality.

This study aimed to evaluate the exogenous progesterone (P4) effect on the luteal function from Day 16 to Day 21 of the oestrous cycle in inseminated goats with unknown pregnancy status. A total of 54 does passed through a short progestin-based synchronization protocol and, on Day 16 of the following oestrous cycle, 27 does received a new P4 device which was retained until Day 21. Blood samples were collected daily from all does during this period, as well as on Day 24. Pregnancy diagnoses were performed on Day 30. Serum P4 values from 26 animals (GNPSP : Group of non-pregnant does with second sponge: n = 8; GNPNSP : Group of non-pregnant does without second sponge: n = 6; GPSP : Group of pregnant does with second sponge: n = 5; GPNSP : Group of pregnant does without second sponge: n = 7) were determined by radioimmunoassay commercial kits. No P4 differences were found between groups (GNPSP : 3.1 ± 2.8; 1.7 ± 1.8; 0.4 ± 1.0; and 0.0 ± 0.0 vs. GNPNSP : 4.4 ± 1.8; 3.0 ± 2.2; 0.8 ± 0.8; and 0.0 ± 0.0 or GPSP : 4.2 ± 1.0; 3.4 ± 0.6; 3.3 ± 1.6; 3.2 ± 0.9; 3.6 ± 1.2; 3.5 ± 1.3; 2.7 ± 1.3 vs. GPNSP : 4.4 ± 1.6; 3.6 ± 1.5; 3.7 ± 1.5; 3.8 ± 1.4; 3.2 ± 1.2; 3.1 ± 1.2; 3.6 ± 1.1; D16, D17, D18, D19, D20, D21, D24, respectively) or for the interaction of group and time. In conclusion, a second progestogen device had no effect on luteolysis or early pregnancy in the following oestrous cycle.

Use of two cloprostenol administrations 11.5 days apart efficiently synchronizes oestrus in photostimulated multiparous dairy goats in the non-breeding season.

This study assessed the efficiency of synchronous oestrous induction by light programme followed by two doses of cloprostenol in acyclic Saanen goats of different parity orders. Primiparous (n = 22) and multiparous (n = 33) goats were subjected to 16 hr of light and 8 hr of darkness for 60 days (D0-D60), starting 10 days after the winter solstice. All goats received 120 µg cloprostenol doses on D130 (morning) and D141.5 (afternoon) (11.5 days apart). Oestrus behaviour, ovarian follicular dynamics and serum progesterone (P4) analyses were recorded from D0 to D174 at different intervals. Animals in oestrus after D141.5 were randomly assigned into two groups: assisted natural mating (NM) or artificial insemination (AI; 10-24 hr after oestrus onset with frozen-thawed semen). From D57 to D120, 89.0% of goats presented large follicles (5-8 mm) and P4 concentrations were subluteal from D0 to D120. More multiparous compared to primiparous goats (54.5%, 18/33 vs. 18.2%, 4/22) exhibited oestrus after both injections. More primiparous compared to multiparous goats (54.5%, 12/22 vs. 12.1%, 4/33) did not exhibit oestrus after any injection. A total of 35 goats (64%) were in oestrus after the second prostaglandin injection and were subjected to NM or AI. The conception rate was similar among primiparous (70.0%, 7/10) and multiparous (68.0%, 17/25) goats but the pregnancy rate differed, being 31.8% (7/22) and 51.5% (17/33), respectively. No interaction was found between parity order and P4 concentrations in does that became pregnant or not. Thus, the association between light programme (60 days, starting at the beginning of winter) and two cloprostenol administrations 11.5 days apart (starting 70 days after the end of the light treatment) resulted in sufficient synchronous oestrous response in multiparous acyclic Saanen goats to reach satisfactory fertility levels after both NM and AI.

Transcervical vs. laparotomy embryo collection in ewes: The effectiveness and welfare implications of each technique.

This study assessed animal welfare in ewes subjected to transcervical (TC) or laparotomy (LP) embryo collection, and the efficiency of these two techniques. Santa Inês ewes (n = 57) received a protocol for estrus synchronization and superovulation. Cervical dilation protocol was initiated 12 h before embryo collection in all ewes. Depending on the success of cervical passage, the embryos were collected from ewes by either TC or LP. Records were made of physiological (rectal temperature (RT) and heart rate (HR)), endocrine (cortisol concentration), biochemical (glycaemia, total proteins, globulin and albumin concentrations), and behavioral variables. Data were recorded before fasting (BF) and sedation (BS), during (DC) and immediately after embryo collection (IAC), and 1 h (1hAC), 3 h (3hAC), 6 h (6hAC), 12 h (12hAC), 24 h (24hAC), and 48 h (48hAC) after embryo collection. The LP and TC procedures were applied to 22 and 35 ewes (with 100.0% and 94.3% of procedures being successful, respectively). The use of LP took longer than TC (P = 0.007) but was less effective in the recovery of uterine fluid and structures (P = 0.0002 and P = 0.0180, respectively), with no difference in the number of viable embryos recovered per animal. The TC procedure induced a greater RT at DC (P = 0.002) and IAC moments (P < 0.0001). The heart rate was greater in TC than LP in IAC (P = 0.036). On the other hand, HR was greater with LP at 12hAC (P = 0.033) and 24hAC (P = 0.002). There was no interaction between the procedures and time on total proteins, albumin, or globulin concentrations. The TC procedure induced greater glycaemia than LP in IAC (P < 0.0001). LP induced greater serum cortisol concentration than TC at DC, IAC, 1hAC (P = 0.0004; P = 0.0006; P = 0.036, respectively), even though it was greater in the TC than the LP procedure at 3hAC (P = 0.008). In conclusion, the TC embryo collection was more effective than the traditional LP procedure. Although both embryo collection procedures affected ewes' welfare, the TC procedure is probably less stressor than the LP.

Hormonal protocols for early resynchronization of ovulation in ewes: The use of progestagens, eCG, and inclusion of early pregnancy diagnosis with color Doppler ultrasound.

This study aimed to evaluate 1) the effect of inserting an intravaginal sponge containing medroxyprogesterone during the late luteal phase on the corpus luteum (CL) function and endogenous production of P4; 2) the effectiveness of two different equine chorionic gonadotrophin (eCG) doses on synchronization of ovulations for a resynchronization treatment; and 3) the inclusion of an early pregnancy diagnosis in an early resynchronization protocol for ovulation in ewes. For all studies, the synchronization protocol was based on a short-term protocol of six days of progestogen treatment plus one dose of prostaglandin F2alpha, one dose of eCG, and gonadorelin acetate after sponge withdrawal. For the first study, the ewes were mated with fertile rams; a second sponge was inserted in half of these ewes 12 days later, and blood samples were collected daily for six days, until sponge withdrawal. For the second study, the ewes were not mated, and received a second sponge during the same period, after which they were divided into three groups according to eCG dose (0, 200, or 300 IU). In the third study, all ewes were artificially inseminated and received the second sponge during the same period. At sponge withdrawal, pregnancy was diagnosed by color Doppler ultrasonography (DUS) of the CL, and only non-pregnant ewes were re-inseminated two days later. In the first study, serum progesterone values were similar regardless of whether an intravaginal sponge had been inserted. In the second study, the ovulation time was more concentrated in those ewes which received 200 IU of eCG. In the third study, there was no difference between the experimental groups (with or without a previous pregnancy diagnosis) in pregnancy rate at the first insemination, accumulated pregnancy rate, and pregnancy loss. The insertion of an intravaginal sponge impregnated with medroxyprogesterone acetate did not affect the endogenous production of P4. The application of 200 IU of eCG provided the best result with regard to the synchronization of ovulations in the resynchronization treatment. Also, the inclusion of an early pregnancy diagnosis with DUS is useful and improves the general results of resynchronization programs, shortening the total working period.

Accuracy of assessment of luteal morphology and luteal blood flow for prediction of early pregnancy in goats.

This study aims to determine the best post-breeding time for an early pregnancy diagnosis in dairy goats, when using luteal morphology and vascularization assessment by B-Mode and color Doppler ultrasonography (US) in association or not with the anechoic uterine content. A total of 131 Saanen goats (2.0 ±â€¯0.5 years old) were used in the two studies. In the first study, pregnancy prediction was daily performed from Day 15-23 post-breeding in 51 does. This was based on a subjective assessment of luteal morphology (B-Mode US), luteal blood flow (color Doppler US), and the presence of anechoic uterine content (B-Mode US). In the second study, pregnancy predictions were performed in 71 does on the best post-breeding day, as determined in the first study (Day 21 using luteal blood-flow assessment and Day 23 using luteal morphological assessment and overall analysis). In both studies, pregnancy diagnosis was confirmed on Day 30 (gold standard method by B-Mode transrectal ultrasonography). The B-Mode and color Doppler US performance in reaching an early pregnancy diagnosis was evaluated by calculating sensitivity (Sens), specificity (Spec), negative and positive predictive values (NPV and PPV), accuracy (Acc), the Kappa index (κ), and the Younden index (J). In Study 1, the pregnancy prediction accuracy progressively increased from Day 17-23 using B-Mode US (D17: 50.98%; D18: 52.94%; D19: 62.75%; D20: 74.51%; D21: 86.27%; D22: 90.20%; D23: 96.08%), and from Day 17-21 using color Doppler US (D17: 49.02%; D18: 54.90%; D19: 70.59%; D20: 86.27%; D21: 96.08%). In the second study, color Doppler, B-Mode, and overall assessments at Day 21 and Day 23, respectively, presented a similar pattern of sensitivity, specificity, and accuracy as was found in the first study. Therefore, both color Doppler and B-Mode assessments can be judged as effective tools for reaching a pregnancy diagnosis in goats as early as on Day 21 and Day 23, respectively, post-breeding.