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.

170 Embryonic loss and pregnancy rate in response to resynchronisation using oestradiol benzoate or injectable progesterone at 14 days after timed AI in Bos taurus×Bos indicus beef heifers

The effect of the exposure of pregnant cattle to oestradiol benzoate (EB) or injectable long-acting progesterone (iP4), as well as their use for early resynchronisation of non-pregnant (NP) females within the second week after timed AI (TAI), is yet to be assessed. This study aimed to assess the pregnancy rate and embryonic loss of cross-bred Bos taurus×Bos indicus beef heifers in response to an EB- or iP4-based resynchronisation strategy implemented 14 days after the first TAI. A total of 677 cyclic heifers (Braford and Brangus; 24 months old) were subjected to an EB/P4 synchronisation protocol for the first TAI (Day 0=TAI). On Day 14, all heifers received a new P4 intravaginal device (1g, Sincrogest, Ourofino Saúde Animal) and were randomly assigned to two groups: EB (1mg intramuscularly, Sincrodiol; n=339) or iP4 (75 mg intramuscularly, Sincrogest Injetável; n=338). On Day 22, P4 devices were removed and heifers underwent colour Doppler ultrasonography evaluation. Non-pregnant females were identified by the assessment of structural regression of the corpus luteum, as previously reported by our group. On Day 22, NP heifers received 1mg of oestradiol cipionate (SincroCP), 250µg of sodium cloprostenol (Sincrocio), and 200IU of equine chorionic gonadotrophin (SincroeCG), and they were inseminated on Day 24. On Day 22, the diameter of the preovulatory follicle (POF) was also recorded. Pregnancy was diagnosed via B-mode ultrasonography on Days 35-40 and 54. Statistical analyses were performed using SAS software (ver. 9.2, SAS Institute Inc.). The MIXED procedure was used to evaluate the POF diameter, and the GLIMMIX procedure was used to develop a multivariate model including treatment, breed, age, farm (1-7), and possible interactions of treatment with farm, breed, and age to evaluate the binomial data (pregnancy rates and embryonic loss). In NP heifers, the diameter of the POF on Day 22 did not differ (P>0.05) between the EB (9.77±0.25mm) and iP4 (9.92±0.22 mm) groups. Exposure to EB or iP4 on Day 14 post-TAI did not influence pregnancy rates as assessed on Day 22 (56.3% (191/339) vs. 60.1% (203/338)) and on Days 35-40 (49.6% (168/339) vs. 53.3% (180/338)). In addition, embryonic loss between Days 22 and 35-40 was not different between the EB (12%, 23/191) and iP4 (11.3%, 23/203) groups. On the other hand, pregnancy rates in heifers submitted to the second TAI were greater (P=0.01) in the EB group (45.95%, 68/148) than in the iP4 group (31.85%, 43/135). In conclusion, improved pregnancy rates can be achieved using 1mg of EB associated with a P4 intravaginal device on Day 14 of the resynchronisation protocol without affecting the first TAI pregnancy rates and embryonic loss. However, further investigation is warranted to assess the lower pregnancy rates obtained in response to the association of iP4 and P4 device. This research was supported by FAPESP (2015/10606-9; 2019/15514-6), Graduate Studies Support Program (PAPG-UNIPAMPA), and Ourofino Saúde Animal.

173 Pregnancy rates in suckled beef cows synchronised with progesterone/oestradiol-based protocol and inseminated with conventional or sexed-sorted semen

An experiment was designed to evaluate pregnancy rates per AI (P/AI) in suckled beef cows synchronised with a progesterone (P4)/oestradiol-based protocol and AI with non-sexed (conventional) semen and with a sexed-sorted semen with 65% X-bearing sperm and 35% Y-bearing sperm that was named SuperConventionalTM. Angus and Hereford suckled cows (n=558), 60-90 days postpartum, with a body condition score of 2 to 3.5 (1-to-5 scale) and 48% (269/558) with a corpus luteum, were randomly allocated to be AI with non-sexed (conventional) or SuperConventional semen. The experiment was performed on 3 farms using straws with sexed-sorted SuperConventional semen containing 6 or 8 million sperm and non-sorted conventional semen with 25 million sperm per straw. Semen was from split ejaculates from two Angus bulls. All cows received a P4 device with 0.6g of P4 (Pluselar, Calier) and 2mg of oestradiol benzoate (Calier) on Day 0. All P4 devices were removed on Day 8, and all cows received 400IU of equine chorionic gonadotrophin (Vetegon, Calier), 150µg of d+cloprostenol (Veteglan, Calier), and 1mg of oestradiol cipionate (Calier) at the same time. All cows were also tail-painted and observed for signs of oestrus. Cows with >30% of the tail paint rubbed off by 48-50h after P4 device removal were AI at that time with either SuperConventional or conventional semen. Those not showing oestrus by 48-50h received 10µg of buserelin (Pluserelina, Calier) at that time and were AI with either SuperConventional or conventional semen 50-52h after P4 device removal. Pregnancy was diagnosed using ultrasonography 60 days after AI, and all pregnancies were sexed to determine the proportion of female pregnancies. Data were analysed using GLM for binary data. The P/AI were different between cows showing or not showing oestrus (P<0.01) but did not differ among the three types of semen used (Table 1). The percentage of cows pregnant with female fetuses was 51% (50/98) for cows AI with conventional semen and 65.5% (55/84) and 65.3% (51/78) for those AI with SuperConventional semen with 8 million or 6 million sperm per straw, respectively. In conclusion, sexed-sorted semen with 65% of X-bearing sperm and 6 or 8 million sperm per straw can be successfully used to inseminate suckled beef cows. Furthermore, results confirm those of previous studies that cows in oestrus at the time of fixed-time AI have higher pregnancy rates than cows not in oestrus in P4/oestradiol-based synchronisation programmes. Table 1.Effect of semen type and oestrus expression on pregnancy rates per AI in suckled beef cows synchronised with a progesterone/oestradiol-based protocol Semen type In oestrus,% (n) Not in oestrus,% (n) Total,% (n) Conventional (25 million sperm) 59.8 (82/137)a 32.0 (16/50)b 52.4 (98/187) SuperConventional (8 million sperm) 53.7 (73/136)a 20.0 (10/50)b 44.6 (83/186) SuperConventional (6 million sperm) 50.4 (63/125)a 26.7 (16/60)b 42.7 (79/185) Total 54.8 (218/398)a 26.3 (42/160)b a,bDifferent superscripts denote differences in pregnancy rates per AI between cows in oestrus and not in oestrus by the time of fixed-time AI (P<0.01). Research was supported by Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550) and UNVM.

226 Effect of the presence or absence of corpus luteum in females with small antral follicles at the beginning of a progesterone-based oestrus synchronization protocol on superovulatory response and embryo yields in sheep

The high variability of responses to multiple ovulation and embryo transfer (MOET) programs is related to several factors, including the ovarian population present at the beginning of hormonal protocols. Thus, our objective was to evaluate the effect of the presence or absence of corpus luteum (CL) in females presenting small antral follicles (SF) at the beginning of a progesterone (P4)-based oestrus synchronization protocol on superovulatory response and embryo yields. The study was conducted during September and October in northeast Brazil (03°40′26″S and 40°14′20″W) using 15 adult Santa Inês ewes, in which the ovarian population present were SF (≤3.75mm, n=5) or SF plus CL (SF+CL, n=10) at the beginning of P4-based oestrus synchronization protocol. The females received a new or reused intravaginal device of progesterone (CIDR Eazi-breed, Zoetis) on Day 0, which remained for 9 days. On Day 7, the pFSH (133mg, Folltropin V, Vetoquinol) treatment was begun, with 6 decreasing doses (25, 25, 15, 15, 10, and 10%) injected IM at 12-h intervals. On Day 9, two equal doses of D-cloprostenol were injected at a 12-h interval (37.5μg, Prolise, Agener União). Flunixin meglumine (24.9 mg; Banamine, MSD Animal Health) was administered IM on Days 13 to 15. All ewes showed oestrus and were mated with fertile rams. On Day 16 non-surgical embryo recovery (NSER) was performed after cervical dilation using D-cloprostenol and oestradiol benzoate at 16h and ocytocin at 20min before. Transrectal B-mode ultrasound evaluations (Z5 Vet, Mindray) were performed on Day 0 and just before NSER to evaluate the ovarian population present. Data are showed in mean±s.d. and compared by t-test for independent samples (P<0.05). The number of CL present on NSER day (21.5±4.4 and 4.0±8.5) and the number of viable embryos (11.1±14.9 and 4.0±8.5) differed (P<0.05) between SF+CL ewes and SF ewes, respectively. However, the number of luteinizing unovulated follicles present on NSER day (4.5±2.5 and 12.4±7.8) and the number of recovered structures (i.e. embryos plus unfertilized eggs; 14.2±15.6 and 4.2±8.2) did not differ (P>0.05) between SF+CL ewes and SF ewes, respectively. In conclusion, the presence of a CL at the beginning of the oestrous synchronization protocol used for superovulation treatment affects responses to the MOET program. Financial support for this study was provided by Embrapa (02.13.06.026.00.02 and 02.13.06.026.00.04) and FAPEMIG (PPM 00201-17).

Efficiency of mating, artificial insemination or resynchronisation at different times after first timed artificial insemination in postpartum Nellore cows to produce crossbred calves

The objective of this trial was to evaluate different post-timed artificial insemination (TAI) reproductive managements in postpartum beef cows to produce crossbred calves from artificial insemination (AI). Nellore cows (n = 607), with 45 days postpartum, were inseminated at a fixed time, using a protocol that included an intravaginal progesterone-releasing device along with oestradiol benzoate, prostaglandin, equine chorionic gonadotropin, and oestradiol cypionate, followed TAI 48 h post-device removal. Four post-TAI treatments were evaluated: in CONTROL (T1, n = 161), cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). In OBSERVATION (T2, n = 132), heat detection was performed for 15–25 days post-TAI, followed by AI. In RESYNC22 (T3, n = 157) and RESYNC30 (T4, n = 157), resynchronisation started after 22 or 30 days, following second TAI at Day 32 or 40 days after first TAI. In T2, T3 and T4, after the second AI, cows were exposed to Nellore clean-up bulls until the end of the breeding season (75 days). The pregnancy rate (PR) for the first TAI did not differ (54.6%, 53.0%, 59.2%, and 51.6% for CONTROL, OBSERVATION, RESYNC 22, and RESYNC 30, respectively; P = 0.66), and no difference was observed for the second TAI (RESYNC 22 = 45.31% and RESYNC30 = 46.05%; P = 0.137), in the PR at the end of the breeding season (86.33%, 86.36%, 78.98%, and 81.52%, P = 0.43), or embryonic losses (4.54%, 2.85%, 6.45% and 7.40%, respectively; P = 0.61), but the percentage of crossbred pregnancy was higher in groups with resynchronisation (RESYNC22 and RESYNC30) than CONTROL and OBSERVATION (98.38%, 90.62%, 63.30%, 78.95%, P < 0.001). In conclusion, resynchronisation programs of 22 or 30 days are more efficient to produce AI products, and the final pregnancy rate is similar among the treatments, differing only in the amount of calves produced by AI.

10 Effect of 1 or 2 doses of prostaglandin in a resynchronization protocol for timed artificial insemination in beef cows

The objective of this study was to compare the effects of 1 and 2 prostaglandin doses in a timed AI (TAI) resynchronization protocol on the pregnancy rate. This study was performed during the 2017-2018 breeding season on 10 commercial farms located in the central and southwest region of Rio Grande do Sul, Brazil. A total of 2347Bos taurus beef cows (Angus, Hereford) with a body condition score 2.90±0.15 (1=thin, 5=obese) and 40±5.1 days postpartum were used. In the beginning of first synchronization TAI protocol, on Day −11, the animals received 2mg of oestradiol benzoate IM (Gonadiol®, Zoetis Saúde Animal, São Paulo, SP, Brazil) and a progesterone (P4) intravaginal device (CIDR®, Zoetis). On Day −4, the cows received 12.5mg of dinoprost tromethamine IM (PGF, Lutalyse®, Zoetis). On Day −2, the animals received 1.0mg of oestradiol cypionate IM (ECP®, Zoetis) associated with the treatment with 300IU of eCG IM (Novormon®, Zoetis) and the P4 device was removed. The TAI was done on Day 0 (48 h after P4 device removal). The resynchronization protocol was started on Day 23 without pregnancy or oestrus detection; all cows were randomly assigned to receive a new, once-used, or twice-used P4 device (CIDR®) and given 2mg of oestradiol benzoate. On Day 30, pregnancy diagnosis was performed with transrectal ultrasonography. Pregnant cows (n=1021) had the P4 device withdrawn and received no further treatment. Nonpregnant cows (n=1326) were randomly assigned into 2 groups. The 1PGF group (n=674) received a single dose of PGF on Day 30, and the 2PGF group (n=652) received PGF on Days 30 and 32. On Day 32, all cows received eCG and ECP, and the P4 device was removed. In both groups the TAI was performed 48h after the P4 device removal (Day 34). Pregnancy diagnosis was performed by ultrasound 30 days after TAI (Day 64 of the breeding season). Data were analysed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC, USA). The pregnancy rate obtained in the first synchronization protocol was 43.5% (1021/2347). The pregnancy rate in the resynchronization protocol was similar (P=0.49) between PGF doses [1PGF=39.5% (266/674); 2PGF=40.6% (265/652). No interactions were observed between P4 device use and PGF dose (P=0.38). The pregnancy rates were similar when comparing 1PGF and 2PGF using a new P4 device [1PGF=43.2% (35/81); 2PGF=56% (93/166); P=0.67], once-used P4 device [1PGF=39% (163/418); 2PGF=40.6% (140/345); P=0.64], or twice-used P4 device [1PGF=38.9% (68/175); 2PGF=22.7% (32/141); P=0.14]. In conclusion, a second dose of prostaglandin in the resynchronization protocol was not necessary to achieve high resynchronization pregnancy rates with TAI in Bos taurus beef cows.

7 Pregnancy rates in suckled beef cows synchronized with a shortened progesterone/oestradiol-based protocol (J-synch) and inseminated with conventional or sexed-sorted semen

An experiment was designed to evaluate pregnancy rates (P/AI) in suckled beef cows synchronized with a progesterone (P4)/oestradiol-based protocol (J-Synch) and inseminated (AI) with sexed or nonsexed (conventional) semen. Angus or Angus crossbred cows (n=877), 60 to 90 days postpartum, with a body condition score of 2.5 to 3.5 (scale of 1 to 5) and a corpus luteum or a follicle >8mm in diameter detected by ultrasonography, were randomly allocated to be AI with sexed-sorted or nonsexed (conventional) semen. The experiment was performed in 4 farms, and the sexed-sorted (SexedUltra™ 4M, with 4 million sperm; ST Genetics, Navasota, TX, USA) and conventional (25 million sperm) semen were from split ejaculates from 5 Angus bulls. All cows received a P4 device (DIB 0.5, Zoetis, Villa Adelina, Argentina) and 2mg of oestradiol benzoate (Gonadiol, Zoetis) on Day 0. On Day 6, cows received 400IU of eCG (Novormon 5000, Zoetis) and 500µg of cloprostenol (Ciclase DL, Zoetis) and DIB was removed. All cows were also tail painted and observed for signs of oestrus (i.e. >30% of the tail paint rubbed off) at 60, 72, and 84h after DIB removal. Cows with the tail paint rubbed off by 60 or 72h after DIB removal were artificially inseminated at 72h with either sexed or conventional semen. Those not showing oestrus by 72h received 100µg of gonadorelin acetate (Gonasyn GDR, Zoetis) at that time and were artificially inseminated with either sexed-sorted or conventional semen 12h later (i.e. 84h). Pregnancy was diagnosed by ultrasonography 30 days after AI. Data were analysed by general linear model for binary data with a logit link. Overall, 76.4% (678/877) of cows showed oestrus 60 to 84h after DIB removal, and there were differences in P/AI between sexed-sorted and conventional semen (P<0.01; Table 1); however, there was no farm effect (range: 52-59%) and no interactions. Fertility differed (P<0.05) among bulls and ranged from 25.8 to 55.3% for sexed-sorted semen and from 53.1 to 73.9% for conventional semen. In cows artificially inseminated with sexed-sorted semen, P/AI was the highest in cows showing oestrus and AI at 84 h; however, no differences were detected among cows artificially inseminated with conventional semen (Table 1). Although P/AI was lower for sexed-sorted than conventional semen, tail painting for oestrus detection can be successfully applied to AI beef cows with sexed-sorted semen synchronized with a shortened P4/oestradiol-based protocol. Table 1.Effect of semen type (sexed-sorted or conventional) and time of oestrus and AI on P/AI in suckled beef cows synchronized with a shortened P4/oestradiol-based protocol Research was supported by Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550) and UNVM.

11 Conception rate of high-producing dairy cows at first service using prostaglandin F2α and oestradiol benzoate

We have shown that a simplified oestrus synchronization protocol using prostaglandin F2α (PG) and oestradiol benzoate (EB) resulted in a satisfactory conception rate, similar to that obtained in high-producing dairy cows with natural oestrus (Yamaguchi et al. 2018 Reprod. Fertil. Dev. 30, 147 abstr). However, we found no significant effect of PG+EB protocols on the first-service conception rates (CR) of dairy cows. This study investigated the effect of the first-service CR by using PG+EB protocols in the high-producing dairy cows that had not exhibited oestrus expression after calving. Data concerning the first-service CR were obtained for 481 Holstein cows from 4 commercial dairy herds in Hokkaido and Ibaraki, Japan, from 2014 to 2017. The average number of parity, average interval between calving and the first service, and average milk yield (at 305 days) of the cows were 2.2±1.3, 89.7±26.1 days, and 10314±1994kg, respectively. We carried out the PG+EB protocols on cows not showing evident standing heat from Days 50 to 150 postpartum regardless of the presence of a corpus luteum in the ovary. The statuses of ovaries of cows were confirmed using ultrasonography before starting the treatment. Prostaglandin F2α (25 mg; Lutalyse, Pfizer, New York, NY, USA) was injected into cows with a >20mm cutoff for functional corpus luteum diameter at a random stage of oestrus, and EB (1 mg; Ovahormon®, Aska Animal Health Co., Tokyo, Japan) was injected 24h later, and AI was carried out 24 to 48h after EB injection. Cows with a natural oestrus service from Days 50 to 150 postpartum were used as control. All the cows were inseminated after the onset of standing heat or removal of the tail chalk. Pregnancy diagnoses were performed using ultrasonography 30 to 45 days after AI. The CR and intervals of partum to conception were analysed using a chi-square test and ANOVA. The first-service CR (i.e. the number of pregnant cows/total number of cows in the treatment group) of the natural oestrus (n=330) and PG+EB (n=151) groups were 42.7 and 41.1%, respectively, and there were no significant differences between these 2 groups (P=0.7). The average interval between calving and the first service of the PG+EB groups was significantly longer than that of the natural oestrus groups (86.4±1.5 days v. 96.9±1.9 days; P<0.01). The average days open of the natural oestrus and PG+EB groups were 88.5±3.2 days and 98.1±2.3 days, respectively (P<0.05). These results confirmed that the first-service CR in the PG+EB and natural oestrus groups of high-producing dairy cows were similar. We suggest that conducting PG+EB protocols was effective in the high-producing dairy cows that had not exhibited oestrus expression after calving. Moreover, using PG+EB protocols could prevent the further increase in the number of days open.