Gonadotropin‐induced Puberty Does Not Impair Reproductive Performance of Gilts over Three Parities

The aim of this study was to evaluate the reproductive performance of three parities of gilts treated or not treated with gonadotropin to induce puberty. Sixty gilts received 600 IU of equine chorionic gonadotropin (eCG) followed by 2.5 mg of porcine luteinizing hormone (LH) 72 h later. Fifty‐nine other gilts were exposed only to a mature boar for 15 min twice daily. Artificial insemination (AI) was performed at 0, 12 and 24 h after the detection of oestrus, and gestation was confirmed by ultrasound after 35 days. Sows were inseminated at the first post‐weaning oestrus. The total numbers of piglets born, piglets born alive, stillborn, mummified foetuses, as well as pregnancy and farrowing rates were evaluated for each of the three parities. Culling rates, farrowing intervals and weaning‐to‐oestrous intervals (WEI) were also analysed. Mean age at puberty and oestrous manifestation were not significantly different between treatments (p = 0.0639; 179.20 ± 17.52 compared with 173.96 ± 16.94, 91.66% compared with 94.92%) across the experimental period. However, females that underwent puberty induction showed modest increases both in the number of total pigs born and in the number of piglets born alive. In conclusion, puberty induction through exogenous gonadotropin administration in field conditions did not induce a more concentrated first oestrous manifestation, but trended to a modest increase in the number of pigs born alive in the first parity and a reduced culling rate during the first gestation.     

Effect of Inter‐Breed Embryo Transfer on Lamb Growing Performance and Survival

The roles of recipient and embryo genotype in determining the growth performance and survivability of offspring based on specific behavioural differences were investigated using inter‐breed embryo transfer. This study was carried out using three recipient genotypes (Awassi, Redkaraman and Tuj) and two embryo genotypes (Charollais and Romanov) to obtain the six possible combinations of ewe and lamb genotypes. Data were collected from 71 recipient ewes (10 Redkaraman with Charollais and 15 Redkaraman with Romanov embryos; 10 Tuj with Charollais and 12 Tuj with Romanov embryos, and 12 Awassi with Charollais lambs and 12 Awassi with Romanov embryos); all ewes received two frozen‐thawed embryos. Awassi ewes had a significantly longer duration of the licking/grooming event (25.5 min, p < 0.05) than Tuj ewes. Charollais lambs were significantly (p < 0.05) more likely to require birth assistance compared to Romanov lambs. Romanov lambs were significantly more (p < 0.01) active than Charollais lambs in the first 2 h after birth; ewe breed had no effect on lamb behaviour. There was no recipient breed effect on either birth or weaning weights of lambs. Charollais lambs were recorded with higher birth (5.5 ± 0.3 kg vs 3.9 ± 0.2 kg; p < 0.001) and weaning (29.4 ± 1.2 kg vs 22.4 ± 1.9 kg; p < 0.001) weights compared to Romanov lambs. At weaning Romanov lambs had significantly higher (95% vs 75%; p < 0.05) survival rates, however, this was not significantly affected by recipient breed. It was concluded that recipient breed was not an important factor in survival and weaning performance of embryo transferred lambs from a prolific breed (Romanov) while these traits recorded for lambs from meat type (Charollais) embryos were influenced by dam breed.     

Practical Experience with the Treatment of Recipient Mares with a Non‐Steroidal Anti‐Inflammatory Drug in an Equine Embryo Transfer Programme

As part of a commercial embryo transfer programme, 20 embryos were transferred to spontaneously synchronous or synchronized recipient mares. In 14 cases, embryo recipients were treated with non‐steroidal anti‐inflammatory drugs (NSAID), receiving flunixin meglumine i.v. at the time of transfer and vedaprofen orally twice a day on the 3 days after embryo transfer, while six embryos were transferred to untreated mares that served as controls. Out of the 14 recipient mares treated with NSAID, 11 (79%) were pregnant at 6–8 days after transfer and in 10 mares, the pregnancy was continued. From the six untreated recipients, only one became pregnant but underwent early embryonic death between day 14 and 35 after ovulation. In conclusion, pregnancy rate in NSAID‐treated recipients is higher than that in untreated recipients and above reported average values, indicating that treatment of recipient mares with NSAID helps to increase pregnancy rates after transcervical transfer and can be recommended for equine embryo transfer.     

Reproductive Performance and Reconception of Nellore Cows According to Their Pure‐ or Cross‐Bred Calves

The objective of the present research was to evaluate the effect of a calf's genetic group on the productive and reproductive efficiency of its Nellore dam. Fixed‐time artificial insemination was applied to 800 cows using semen extracted from Nellore, Simmental and Angus Red bulls. Four hundred eleven cows calved, producing 119 Nellore, 103 ½Simmental–½Nellore and 189 ½Nellore–½Angus Red calves. The second mating period, which paired Nellore cows with Simmental bulls, was initiated 10 days after parturitions began and lasted for 5 months. Based on the two successive parturitions, the cumulative parturition rate for calving periods of 3, 4 and 5 months was calculated. Although no significant difference was observed for birth weight among the genetic groups, cross‐bred calves weighed, on average, 10% more than did pure‐bred calves at the age of 205 days. Nellore dams experienced a gestation period that was 7 days longer than did the cross‐bred dams, and the former showed a higher parturition rate at 90 and 120 days of the calving season, but not at 150 days (calving rates of 80.6, 76.4 and 76.2% for mothers of Nellore, ½Nellore–½Angus Red and ½Nellore–½Simmental, respectively, p > 0.05). At 90 and 120 days, Nellore dams produced more kg of calf per mated dam. In conclusion, in a short breeding season, Nellore dams nursing pure‐bred Nellore calves were found to have a higher biological efficiency compared with Nellore dams nursing cross‐bred calves.     

Absence of Sperm Factors as in the Parthenogenesis Does Not Interfere on Bovine Embryo Sensitiveness to Heat Shock at Pre‐Implantation Stage

Oocyte has been considered the major contributor for embryo thermo‐tolerance. However, it was shown that sperm factors can be transferred to the oocyte during fertilization, raising the question of whether the absence of such factors could interfere on embryo thermo‐tolerance. In this study, we used parthenogenesis to generate bovine embryos without spermatozoa in order to test whether the absence of sperm factors could influence their thermo‐sensitiveness at early stages. In vitro fertilized (IVF) and parthenogenetic (PA) embryos at 44 h post‐insemination/chemical activation were exposed to 38.5°C (control) or 41°C (heat shock) for 12 h and then developed for 48 h and up to blastocyst stage. Apoptosis index and expression of PRDX1, GLUT1, GLUT5 and IGF1r genes in blastocysts derived from heat‐shocked embryos were also evaluated. The heat shock decreased the blastocyst rate at day seven (p < 0.05) for IVF embryos and at day eight (p < 0.01) for both IVF and PA embryos. Total cell number was not affected by heat shock in IVF and PA blastocysts, but there was an increased proportion (p < 0.05) of apoptotic cells in heat‐shocked embryos when compared to controls. There was no interaction (p > 0.05) between method of activation (IVF and PA) and temperature (38.5°C or 41.5°C) for all developmental parameters evaluated. Expression of GLUT1 gene was downregulated (p < 0.05) by heat shock in both IVF and PA blastocyst whereas expression of GLUT5 and IGF1r genes was downregulated (p < 0.05) by heat shock in PA blastocysts. Those data show that the heat shock affects negatively the embryo development towards blastocysts stage, increases the apoptotic index and disturbed the expression of some genes in both IVF and PA embryos, indicating that the presence or absence of sperm factors does not influence the sensitivity of the bovine embryo to heat shock.     

The Post‐Cervical Insemination does not Impair the Reproductive Performance of Primiparous Sows

The study evaluated the reproductive performance of primiparous sows submitted to post‐cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60 min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning‐to‐oestrus interval and total born in previous farrowing, in two treatments: PCAI (n = 165) with 1.5 × 10⁹ sperm cells in 45 ml (2.4 ± 0.04 doses per sow) and CAI (n = 165) with 3 × 10⁹ sperm cells in 90 ml (2.5 ± 0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real‐time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24 h after last insemination. There was no difference (P > 0.05) between treatments in farrowing rate (91.5% × 89.1%) and litter size (12.5 × 11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P > 0.05). Bleeding during insemination did not affect (P > 0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P ≤ 0.06). Percentage of spermatozoa present in backflow within 1 h after insemination was greater in CAI than PCAI sows (P < 0.01). More than 85% of primiparous sows can be successfully post‐cervical inseminated with doses containing 1.5 × 10⁹ sperm cells in the absence of the boar during insemination without impairing the reproductive performance.     

The Anti‐Müllerian Hormone Profile is Linked with the In Vitro Embryo Production Capacity and Embryo Viability after Transfer but Cannot Predict Pregnancy Outcome

The current study investigated the possibility of using the AMH concentration as a predictor of the ability of Korean Hanwoo cows to produce cumulus‐oocyte complexes, embryos that survive after transfer as well as the pregnancy outcome of surrogates. Eight sessions of ovum pick‐up (OPU) were performed with 19 donor cows at an interval of 3–4 days. Antral follicle count (AFC), oocyte quality and in vitro embryo development were recorded for each cow. Embryos produced from cows with different AMH profiles were transferred into recipients (n = 96). Cows in the high (≥0.25 ng/ml) and intermediate (0.1≥ to <0.25 ng/ml) AMH groups had a significantly higher AFC per OPU session (20.40 ± 1.36 and 16.91 ± 1.52, respectively; mean ± standard deviation) than cows in the low AMH group (<0.1 ng/ml; 12.19 ± 2.14). In addition, more cumulus‐oocyte complexes per donor were recovered in the high (11.46 ± 1.22) and intermediate (7.38 ± 0.83) AMH groups than in the low AMH group (4.77 ± 0.44). The percentage of oocytes reached blastocyst stage was significantly higher in the intermediate (47.0%) and high (38.5%) AMH groups than in the low AMH group (32.3%). The number of embryos produced per cow was higher in the high (3.9 ± 0.2) and intermediate (6.9 ± 0.6) AMH groups than in the low AMH group (2.2 ± 0.3). The percentage of embryos that gave birth to viable calves when transferred into recipients was higher for those derived from cows in the intermediate AMH group (50.7%) than for those derived from cows in the low (35.7%) and high (36.4%) AMH groups. In conclusion, a single measurement of AMH concentration predicted the in vitro embryo production potential of donor Korean native cows before OPU and is linked with embryo viability after transfer into recipients.