14 IS THE LOW NUMBER OF OVARIAN ANTRAL FOLLICLES ≥3mm IN DIAMETER ASSOCIATED WITH LOW FERTILITY IN LACTATING NELORE COWS?

The follicular growth in cattle occurs in a wave pattern of 2 to 3 waves per oestrous cycle and is characterised by synchronous growth of a cohort of antral follicles, where usually only one of these will become dominant. The amount of recruited follicles per wave is variable between animals and breeds but is highly repeatable among individuals. Some studies report that in Bos indicus the amount of follicles recruited by wave is higher when compared with Bos taurus. The variation in the size of the ovarian follicular population can affect fertility by influencing oocyte competence (Ireland et al. 2007). We aimed to identify Nelore (Bos indicus) cows with high and low numbers of antral follicles recruited by follicular wave and to compare their pregnancy rates. We used 268 multiparous Nelore cows between 40 and 70 days postpartum and body condition score between 3.5 to 4.5 (5-point scale). The cows were sorted in ascending order according to the average number of follicles at all examinations (≥3 mm in diameter). Hence, 33% of animals with the greater follicular population were enrolled in the high population group (HG, n = 89, ≥38 follicles), whereas the intermediate animals (33%) were placed in the intermediate group (IG, n = 88, between 28 and 38 follicles), and animals (33%) with lower follicular population were included in the low population group (LG, n = 91, ≤28 follicles). The animals underwent 3 ultrasound examinations (days D–10, D0, and D28). In D0, at random day of the oestrous cycle, all cows received an intravaginal device containing progesterone (1.0 g, DIB®) and oestradiol benzoate (EB, 2.0 mg, IM, Estrogin®). Eight days later (D8) we administered 75 μg of d-cloprostenol (Croniben®), and the intravaginal device was removed. Twenty-four hours after DIB removal, the cows were treated with EB (1.0 mg, IM), and after 30 to 36 h animals were AI at a fixed time. Data were analysed using PROC GENMOD SAS System 9.1 for Windows (2002–2003). The mean (±SD) of antral follicles in both ovaries was 32.7 ± 17.8. There was no difference (P = 0.144) in pregnancy rates between the HG, LG, and IG animals (32.6, 46.6, and 42.9%, respectively). Thus, we conclude that there was no difference in pregnancy rates between Nelore cows either with high or low population of ovarian antral follicles after AI at a fixed time.Research was supported by grants #2013/02201-3 (VGP), #2011/50259-5 (RLE), #2012/23409-9 (EMR), #2012/50533-2 (MFGN), São Paulo Research Foundation (FAPESP).

63 EVALUATION OF HYPOTHALAMIC–PITUITARY RESPONSIVENESS DURING THE POSTPARTUM NELLORE COWS

The presence of calf, body condition score, energy balance, number of births (multiparous vs primiparous) and breed are factors that influence the duration of postpartum anoestrus in beef cows. The objective of the present study was to evaluate, during early postpartum, the time of re-establishment of pituitary LH stocks, measured by the hypothalamic-pituitary-axis responsiveness to exogenous administration of gonadotropin-releasing hormone (GnRH) or oestradiol benzoate (EB). Multiparous lactating Nellore cows (Bos indicus, n = 65) were randomly allocated into 6 groups, according to the hormonal treatment: EB group (1.0 mg of EB, IM, n = 7), GnRH group (50 μg of lecireline, IM, n = 16). The EB-supplemented (SUP; n = 9) and GnRH-SUP (n = 16) groups received the same treatments specified above and were SUP with a balanced diet, based on cotton meal and ground corn (3.5 kg cow–1 per day). Additionally, animals from EB-calf removed (CR; n = 4) and GnRH-CR (n = 13) groups received the same treatments of EB and GnRH group, respectively and had their CR shortly after parturition. The hormones were administered weekly, from 7 days postpartum (±5 days) until the occurrence of the first ovulation, which was determined by the presence of corpus luteum during ovarian ultrasonography performed weekly. Blood samples were collected just before and 2 h (GnRH groups) or 18 h (EB groups) after hormone administration, in order to determine LH concentration by radioimmunoassay. Data were analysed by ANOVA. Mean values in days (± standard error of the means) for the first postpartum LH surge were EB (73.0 ± 5.2); EB-CR (16.7 ± 5.8); EB-SUP (41.7 ± 6.7); GnRH (32.3 ± 3.0); GnRH-CR (11.0 ± 3.5); GnRH-SUP (15.6 ± 2.8). There were significant differences (P < 0.05) between groups EB vs EB-CR; EB vs EB-SUP; BE vs GnRH; GnRH vs GnRH-CR; GnRH vs GnRH-SUP and a tendency between EB-SUP vs EB-CR (P < 0.10). Results indicate that from the second week postpartum, there is sufficient LH in the pituitary to induce ovulation after GnRH or EB administration. However, the cows from the EB group ovulated later than animals from the other groups, possibly due to the sensitivity of the hypothalamus to negative feedback of estrogens, inhibiting the pre-ovulatory LH surge. Additionally, CR and food SUP reduced in 2 to 4 weeks the time of the first postpartum LH surge induced by GnRH or EB in Nellore cows. A fellowship was received from FAPESP. Support was received from FAPESP.

25 ADDITION OF FSH, IN CONTRAST TO eCG, DOES NOT INCREASE PREGNANCY RATES IN ANESTROUS NELLORE (BOS INDICUS) COWS TREATED WITH FIXED-TIME AI PROTOCOL

There are reports in the literature indicating that use of eCG improves pregnancy rates in Bos indicus anestrous cows treated with a progesterone-based fixed-time AI (FTAI) protocol. More recently, replacement of eCG by FSH in FTAI protocols was reported to have beneficial effects (Bos indicus) or no effect (Bos taurus) on pregnancy rates. In the present experiment the effects of eCG and FSH on pregnancy rates were compared in an FTAI protocol. Primiparous lactating Nellore cows (40 to 80 days postpartum, n = 421) with a body condition score of 2.5 to 3.0 (on a 1 to 5 scale) were randomly allocated in 3 groups: Control (CTR), eCG, and FSH. In the control group, all animals received a progesterone (P4)-releasing intravaginal device (1.55 g, PRID®, Ceva Sante Animale S.A., Libourne, France) and 2.5 mg of estradiol benzoate (EB, i.m. Estrogin®, Farmavet, São Paulo, Brazil), on Day 0 (D0). Eight days later (D8), at the time of the intravaginal device withdrawal, PGF2α (150 μg, D-cloprostenol, i.m. Prolise®, ARSA S.L.R., Buenos Aires, Argentina) was administered. Twenty-four hours after PRID removal, cows were treated with EB (1.0 mg, i.m.), and FTAI was done 30 to 36 h later. In the eCG and FSH groups, the cows were treated with 20 mg of FSH (Folltropin-V®, i.m. Bioniche, Belleville, Canada) or400IU of eCG (Novormon®, i.m. Syntex, Buenos Aires, Argentina), respectively, at the time of PGF2α administration. Ovarian ultrasonography (Aloka SSD 500, 7.5-MHz probe, Aloka, Tokyo, Japan) was performed 10 days prior to and at the beginning of FTAI protocol to select the animals in postpartum anestrous (absence of CL in both examinations). The pregnancy diagnosis was performed by ultrasonography 30 days after FTAI. Data were analyzed by logistic regression (SAS Institute, Cary, NC, USA). Cows treated with eCG had a higher pregnancy rate (41.5%, 95/229; P < 0.05) than those treated with FSH (22.7%, 22/97) or in the control group (26.3%, 25/95). Pregnancy rates of animals treated with FSH did not differ (P > 0.05) from those in the control group. These results indicated that, in lactating primiparous anestrous Nellore cows, the use of eCG in a FTAI protocol improves the pregnancy rate, whereas FSH has no beneficial effect. V. G. Pinheiro received a fellowship from FAPESP (São Paulo, Brazil). The authors are grateful to Ceva Animal Health for providing the intravaginal devices (PRID®) used in this experiment.

132 INDUCTION OF FIRST POSTPARTUM OVULATION AFTER ADMINISTRATION OF GnRH, ESTRADIOL BENZOATE, OR LH ASSOCIATED OR NOT WITH CALF REMOVAL IN NELORE COWS

There are reports in the literature indicating that the presence of calf, body condition score, energy balance, number of births (multiparous v. primiparous), and breed are factors that influence the duration of postpartum anoestrus in beef cows. The purpose of the present study was to evaluate, during early postpartum, the time necessary for reestablishment of pituitary LH stocks, determined by the hypothalamic-pituitary axis responsiveness to exogenous administration of GnRH and estradiol benzoate (EB). Multiparous lactating Nelore cows (n = 51) were kept in Brachiaria brizantha pasture. The animals were randomly allocated in 8 groups, according to the hormonal treatment: EB Group (1.0 mg of EB, i.m. Estrogin®, Farmavet, Sao Paulo, Brazil; n = 7), EB and calf removal (CR) group (EB/CR, calves were removed at the time of birth, n = 4), EB/SUP group (cows were supplemented with a balanced diet, based on cotton meal and ground corn, from the beginning of the experiment until ovulation), GnRH group (100 μg, licereline, i.m. Gestran Plus®, ARSA SLR, Buenos Aires, Argentina; n = 7), GnRH/CR group (n = 4), GnRH/SUP group (n = 8), LH group (12.5 mg, i.m. Lutropin® Bioniche, Ontario, Canada; n = 7), and control group (did not receive any hormone to induce ovulation or diet supplementation, n = 5).The hormones were administered weekly, from 7 days postpartum (±5 days) until the occurrence of the first ovulation, which was determined by the presence of CL during weekly ovarian ultrasonography (Aloka 900, Tokyo, Japan, 7.5 MHz probe). The data were analyzed by ANOVA. On average (±SEM) the first ovulation occurred 86.7 ± 0.5 (EB); 19.7 ± 0.6 (EB/CR); 57.8 ± 0.4 (EB/SUP); 44.7 ± 0.5 (GnRH); 25.9 ± 0.6 (GnRH/CR); 32.8 ± 0.4 (GnRB/SUP); 42.4 ± 0.5 (LH); and 59.3 ± 0.5 (control) days postpartum. There were significant differences between groups: EB v. EB/SUP (P < 0.01), EB v. EB/CR (P < 0.01), EB v. control (P < 0.04), EB v. GnRH (P = 0.01), and there was a tendency between groups: GnRH v. GnRH-SUP (P = 0.10) and LH v. control (P = 0.10). The first ovulations were detected from the second week postpartum (animals from Groups GnRH and EB/CR) until the last ultrasound examination on Day 120 postpartum (Group EB). The results indicate that from the second week postpartum there is sufficient LH in the pituitary to induce ovulation after GnRH or EB administration. However, the cows from EB group ovulated later than animals from the other groups, possibly due to the sensitivity of hypothalamus to negative feedback of estrogens, inhibiting the pre-ovulatory LH surge. Additionally, calf removal and food supplementation reduced in 2 to 4 weeks the time of the first postpartum ovulation induced by GnRH or EB. Fellowship from FAPESP. Supported from FAPESP (Sao Paulo, Brazil).

13,14-Dihydro-15-keto prostaglandin F2α release in response to oxytocin challenge early post-partum in anoestrous Nelore cows submitted to temporary calf removal and progesterone priming

The study evaluated, in early post-partum anoestrous Nelore cows, if the increase in plasma oestradiol (E2) concentrations in the pre-ovulatory period and/or progesterone priming (P4 priming) preceding ovulation, induced by hormonal treatment, reduces the endogenous release of prostaglandin PGF(2)α and prevents premature lysis of the corpus luteum (CL). Nelore cows were subjected to temporary calf removal for 48 h and divided into two groups: GPE/eCG group (n = 10) and GPG/eCG group (n = 10). Animals of the GPE/eCG group were treated with a GnRH agonist. Seven days later, they received 400 IU of eCG, immediately after PGF(2)α treatment, and on day 0, 1.0 mg of oestradiol benzoate (EB). Cows of the GPG/eCG group were similarly treated as those of the GPE/eCG group, except that EB was replaced with a second dose of GnRH. All animals were challenged with oxytocin (OT) 9, 12, 15 and 18 days after EB or GnRH administration and blood samples were collected before and 30 min after OT. Irrespective of the treatments, a decline in P4 concentration on day 18 was observed for cows without P4 priming. However, animals exposed to P4 priming, treated with EB maintained high P4 concentrations (8.8 ± 1.2 ng/ml), whereas there was a decline in P4 on day 18 (2.1 ± 1.0 ng/ml) for cows that received GnRH to induce ovulation (p < 0.01). Production of 13,14-dihydro-15-keto prostaglandin F(2)α (PGFM) in response to OT increased between days 9 and 18 (p < 0.01), and this increase tended to be more evident in animals not exposed to P4 priming (p < 0.06). In conclusion, the increase in E2 during the pre-ovulatory period was not effective in inhibiting PGFM release, which was lower in P4-primed than in non-primed animals. Treatment with EB promoted the maintenance of elevated P4 concentrations 18 days after ovulation in P4-primed animals, indicating a possible beneficial effect of hormone protocols containing EB in animals with P4 priming.

92 INDUCTION OF FIRST POSTPARTUM OVULATION, AFTER ADMINISTRATION OF GONADOTROPIN-RELEASING HORMONE OR ESTRADIOL BENZOATE, IN NELLORE COWS

There are reports in the literature indicating that the presence of calf, body condition score, number of births (multiparous v. primiparous), and breed are factors that influence the duration of postpartum anestrus in beef cows. The purpose of the present study was to evaluate, during early postpartum, the time of the reestablishment of LH stocks, measured by the hypothalamic-pituitary axis responsiveness to exogenous administration of gonadotropin-releasing hormone (GnRH) or estradiol benzoate (EB). Primiparous lactating Nellore cows (n = 38, body condition score 2.5 to 3.5, on a 0 to 5 scale) were kept in a Brachiaria brizantha pasture. The animals were randomly allocated into 2 groups, according to hormone treatment: EB group (1 mg EB, i.m., Estrogin®, Farmavet, Sao Paulo, Brazil; n = 20) and GnRH group (100 μg, licerelina, i.m, Gestran Plus®, ARSA S.L.R., Buenos Aires, Argentina; n = 18). In each group, half of the animals were supplemented with a balanced diet based on cotton meal and ground corn. The drugs were administered from 7 days postpartum (±4 days), at intervals of 7 days, until the occurrence of the first ovulation that was observed by weekly ultrasonography (US, Aloka 900, Tokyo, Japan; 7.5-MHz transrectal probe). The data were analyzed by ANOVA (Proc GLM, SAS Institute, Cary, NC). Within the GnRH and EB groups, the first ovulation occurred 15 and 33 days postpartum, respectively, whereas the group averages (± SD) occurred earlier in cows treated with GnRH compared with those treated with EB (43.0 ± 3.8. v. 75.1 ± 8.7 days postpartum, respectively; P < 0.01). In the EB group, 4 animals did not ovulate until Day 140 postpartum. There was no interaction of treatment (GnRH, EB) × nutrition (supplemented, nonsupplemented). When data from the EB and GnRH groups were combined, there was a significant difference between supplemented and nonsupplemented animals (44.4 ± 6.2 v. 68.9 ± 7.3 days, respectively; P < 0.02). The results indicate that GnRH induces ovulation from Day 15 postpartum, suggesting the presence of sufficient LH in the pituitary to induce the first ovulation at this time. However, EB administration did not induce ovulation in this period, possibly because of the sensitivity of the hypothalamus to negative feedback of estrogens, inhibiting the preovulatory LH surge. These results also indicate that nutritional supplementation anticipates the first postpartum ovulation induced by GnRH or EB. Support by FAPESP(Sao Paulo, Brazil); fellowship from FAPESPA; fellowship from CAPESB.

14 SYNCHRONIZATION OF OVULATION IN ANESTROUS NELORE COWS TREATED WITH HORMONAL PROTOCOL WITHOUT PROGESTERONE OR PROGESTAGENS

Postpartum anestrous cows are usually treated with progesterone/progestagen protocols in order to induce ovulation and sustain pregnancy. In the present work, the efficiency of a protocol (modified GPE), in which temporary calf removal (TCR) and/or administration of eCG, replaced the use of progesterone/progestagens, was evaluated in anestrous animals. Anestrous Nelore cows (40 to 60 days postpartum, n = 22) were randomly allocated to two groups: GPE/eCG and TCR/GPE/eCG. At a random stage of the estrous cycle (D0), animals from Group GPE/eCG were treated with GnRH (50 �g, licereline, i.m., Gestran Plus�; Tecnopec, Sao Paulo, Brazil) and seven days later (D7) they received PGF2� (150 mcg, d-cloprostenol, i.m., Prolise�) and eCG (300 UI, i.m., Novormon�). On D8, estradiol benzoate (EB, 1 mg, Estrogin�; Tecnopec) was administered, and 30 to 36 h afterwards all cows were inseminated at fixed-time (FTAI), without estrus detection. The animals from group TCR/GPE/eCG received the same treatment described above, but with temporary calf removal (during 48 h) before beginning hormonal treatments. The ovaries were examined by ultrasonography (Aloka SSD 500, 7.5 MHz probe) before (D-12, D-2), during (D0, D7, D8), and after (D9, D10, D11, D17, D60) hormonal treatments. The absence of CL, during the ultrasonography performed before starting the treatments, was the criterion used to classify the cows as in postpartum anestrus. Administration of GnRH (D0) induced ovulation (determined by the presence of CL on D7) in 6 of 11 cows (54.5%) from Group GPE/eCG and TCR/GPE/eCG. In relation to synchronization of ovulation after EB administration, in Group GPE/eCG, two cows (18.1%) ovulated until 12 h after FTAI, and four (36.3%) 12 h afterwards (24 h after FTAI). In Group TCR/GPE/eCG, one cow (9%) ovulated approximately 6 h before FTAI, two (18.1%) 12 h after FTAI, and two (18.1%) 12 h afterwards. Preovulatory follicles had a diameter of 11.0 � 1.3 and 11.5 � 2.6 mm in Groups GPE/eCG and TCR/GPE/eCG, respectively. Pregnancy rates, determined by ultrasonograpy 40 to 46 days after FTAI, were 27.2% (3/11) and 45.4% (5/11), respectively. The results indicate that association of TCR with protocol GPE/eCG did not improve synchronization of ovulation or pregnancy rates (P > 0.005). However, increase in pregnancy rates was observed in another experiment with a large number of animals (Pinheiro et al. 2005 Reprod. Fert. Dev. 17, 161, abstr), in which cows from Group TCR/GPE/eCG had higher pregnancy rates (51.5%; 34/66) when compared to animals from Group GPE/eCG (28.3%, 21/74; P < 0.05). This work was supported by FAPESP and by fellowships for A. F. Souza and V. G. Pinheiro from CNPq, Brazil.

18 DO TEMPORARY CALF REMOVAL AND/OR EQUINE CHORIONIC GONADOTROPIN ADMINISTRATION INCREASE PREGNANCY RATES IN LACTATING NELORE COWS TREATED WITH A PROGESTERONE-RELEASE INTRAVAGINAL DEVICE?

Reports indicate that either temporary calf removal or equine chorionic gonadotropin administration can increase the efficiency (pregnancy rate) of hormonal treatments with progestins during postpartum anestrus. This experiment evaluated effects of TCR and/or eCG administration in a protocol with progesterone that is frequently used for fixed-time artificial insemination (FTAI) in cows during postpartum anestrus. The protocols were tested at three farms in lactating Nelore cows (40 to 70 days post-partum, n = 361) with body condition scores from 2.5 to 3.0 (0- to 5-point scale). At a random stage of the estrous cycle (Day 0), animals received a basic PEPE (progesterone-estrogen-prostaglandin-estrogen) protocol with insertion of an intravaginal device with 1.0 g progesterone (DIB�, Syntex, Buenos Aires, Argentina) and an i.m. injection of 2.5 mg of estradiol benzoate (EB, Estrogin�, Farmavet, S�o Paulo, Brazil). Eight days later (Day 8) cows were treated i.m. with 150 mg D-cloprostenol (PGF2� Prolise�, ARSA S.R.L., Buenos Aires, Argentina), and the DIB was removed. Twenty-four hours after DIB removal, cows received 1.0 mg EB i.m. and 30 to 36 h later all animals were FTAIed without estrus detection. Cows were allocated randomly to four groups: PEPE, PEPE/TCR, PEPE/eCG, and PEPE/TCR/eCG. In Group PEPE/TCR, calves were removed temporarily for 54 h (from DIB removal until FTAI). In Group PEPE/eCG, animals received PEPE treatment plus one dose i.m. of 300 UI eCG (Novormon�, Syntex) following PGF2� administration (Day 8). In Group PEPE/TCR/eCG, animals were treated as in protocol PEPE/TCR plus eCG on D8. All animals were examined by ultrasonography (Aloka SSD 500, 7.5 MHz probe) 10 days before and at the beginning of hormonal treatment in order to detect anestrous cows (absence of corpus lutcum in both exams). Pregnancy diagnosis was performed by ultrasonography 30 days after FTAI. The data were analyzed by logistic regression. The following variables were considered in the model and did not affect pregnancy rates: farms, inseminators, and semen (sire). A total of 75% of the animals were in anestrus (absence of CL) and the pregnancy rates were similar (P > 0.05) among the four groups: PEPE (43/85 = 50.6%), PEPE/TCR (42/98 = 42.9%), PEPE/eCG (41/88 = 46%), and PEPE/TCR/eCG (39/90 = 43.3%). The results indicate that in Nelore cows, in postpartum anestrus and good body condition, TCR and/or eCG administration do not improve the efficiency (pregnancy rate) of the PEPE protocol. This work was supported by FAPESP. V.G.P. and A.F.S. received fellowships from CNPq, Brazil.

Silicosis in Brazilian pit diggers: relationship between dust exposure and radiologic findings

The incidental diagnosis of two cases of silicosis at Messejana Hospital, Fortaleza, capital of Ceará state, triggered a field research conducted with the objective of investigating the incidence of silicosis in pit diggers in four towns in the Ibiapaba Mountain Range, at the state's northwestern area, northeastern Brazil. Out of a universe of 1,050 pit diggers in the area, 366 participated in the study; they were all males ranging in age between 16 and 76 years old (average 39 years). The excavation and the sickening process were described and a dust exposure index in pit diggers (DEIPD) was defined. The study sample indicated a rate of 121 (33.06%) silicotics and possibly silicotics. The radiologic findings were related to the DEIPD and indicated significant prevalence of disease. Furthermore, during the research period, from 1986 to 1989, 30 (34.9%) silicotics died of respiratory failure and wasting of body tissues. The data suggested that these men were afflicted with a severe occupational health problem, possibly scattered throughout a large area in northeastern Brazil, where manual pit excavations occur during the whole year and increase during drought periods.