Puberty attainment and reproductive performance of yearling Bos indicus-influenced heifers after two sequential treatments with progesterone.

Number of pubertal heifers at time of breeding season initiation is a primary determinant to pregnancy success during the breeding season. It was hypothesized that pre-breeding progesterone (P4) supplementation (induction) would increase the number of heifers pubertal at the time of imposing estrous synchronization treatment regimens and P/AI. Yearling, Bos indicus-influenced (n = 577) or Bos indicus (n = 174) heifers were or were not treated with P4 (CIDR and Non-CIDR, respectively) for 10 d starting on D-23 (D0 = TAI). Presence of a CL on D-33 or D-23 was considered to indicate heifers were pubertal. On D-13, there was a PGF analogue administered. On D-9, there was treatment with GnRH analogue, 6d-CIDR and PGF. There were inseminations based on estrus (D-2 to D0) or TAI on D0 for non-estrous animals. There were 5.2 % and 62.9 % purebred and crossbred heifers pubertal, respectively. Proportion of prepubertal crossbred than purebred heifers with CL on D-3 was greater as a result of imposing the pubertal induction regimen (P < 0.05 and P> 0.10, respectively). Regardless of puberty status, proportion of heifers in estrus prior to AI in the CIDR group was similar to the heifers of the Non-CIDR group for crossbreds and purebreds. Similarly, P/AI of CIDR group was similar to the Non-CIDR group for crossbreds and purebreds. In summary, imposing the pubertal induction regimen hastened attainment of puberty in yearling crossbred, but not purebred heifers. Puberty induction did not affect estrous response, neither fertility after imposing an estrous synchronization treatment regimen.

Effects of estradiol treatments on PGF2α release in beef heifers submitted to estrous resynchronization 14 days after timed-AI.

The effects of 17ß-estradiol (E2) or estradiol benzoate (EB) on PGF2α release were studied in bred-non-pregnant and pregnant Nelore beef heifers. The day of timed artificial insemination (TAI) was designated day 0 (D0), and a single treatment was given on D14. All heifers also received an intravaginal P4 device on D14, and were randomly assigned to three groups: Control (C, P4 device only, n = 12); E2 (1 mg E2 + 9 mg P4, n = 10); or EB (1 mg, n = 10). Blood samples were collected hourly for 8 hours after treatment (Hours 0-8) to measure plasma concentrations (pg/mL) of a PGF2α metabolite (PGFM). The P4 device was removed on D22 and pregnancy was diagnosed on D28. Pregnancy rate was not different among groups (C, n = 7/12; E2, n = 5/10; EB, n = 5/10). More (P < 0.05) heifers had a CV-identified prominent PGFM pulse (peak of > 100 pg/mL) in E2 group (6/10) than in EB (1/10) and C (0/12) groups. Hourly concentration of PGFM for Hours 0 to 8 showed significant effects of group and hour and an interaction of group by hour but did not show an interaction of group or hour with pregnancy status. In preliminary post-hoc analyses, PGFM concentrations during Hours 0 to 8 and pulse characteristics were analyzed within each pregnancy status. For the non-pregnant heifers, a group-by-hour interaction was detected tentatively indicating an increase (P < 0.005) in PGFM concentrations in E2 group from Hours 4 to 6 and in EB group at Hours 5 and 6. Maximum PGFM concentration during Hours 0 to 8 did not differ (P > 0.1) between E2 (124 ± 23) and EB (110 ± 30) groups, but was greater (P < 0.05) in each group than in C (32 ± 3). Furthermore, PGFM concentrations of pulses at the peak, amplitude, and area under pulse curve (pg/mL/h) were greater (P < 0.05) in E2 group than in C group whereas the EB group did not differ (P > 0.1) from the other groups. For pregnant heifers, no effects of group, hour, or their interaction were detected in PGFM concentrations during the hourly sessions, except that maximum PGFM concentration was greater (P < 0.05) in E2 than in EB and C groups. In addition, the number of prominent pulses was greater in E2 group than in Control or EB groups. In conclusion, PGFM increased earlier and in greater concentration combined for bred-non-pregnant and pregnant heifers treated 14 days after TAI with 1 mg E2 plus 9 mg P4 than with 1 mg EB. Tentatively, a positive effect for each of E2 and EB on PGFM concentrations was attenuated in pregnant heifers.

Type I interferon receptors and interferon-τ-stimulated genes in peripheral blood mononuclear cells and polymorphonuclear leucocytes during early pregnancy in beef heifers.

This study characterised the expression of interferon (IFN)-τ-stimulated genes (ISGs) and Type I IFN receptors in circulating polymorphonuclear cells (PMNs) of beef heifers and compared it with expression in peripheral blood mononuclear cells (PBMCs) up to Day 20 of gestation. Nelore heifers (n=26) were subjected to fixed-time AI (FTAI) on Day 0. PMNs and PBMCs were isolated on Days 0, 10, 14, 16, 18 and 20 after FTAI. The abundance of target transcripts (ubiquitin-like protein (ISG15), 2'-5'-oligoadenylate synthetase 1 (OAS1), myxovirus resistance 1 (MX1), myxovirus resistance 2 (MX2), IFN receptor I (IFNAR1) and IFN receptor 2 (IFNAR2)) was determined using real-time quantitative polymerase chain reaction and compared between pregnant (n=8) and non-pregnant (n=9) females. In both PBMCs and PMNs, ISG15 and OAS1 expression was greater in pregnant than non-pregnant heifers on Days 18 and 20. There were no significant differences in the expression of ISGs between PBMCs and PMNs. A time effect on expression was found for IFNAR1 in PBMCs and IFNAR2 in PMNs, with decreased expression of both genes on Days 18 and 20. When the expression of these genes was compared between cell types only in pregnant heifers, IFNAR2 expression in PMNs had an earlier decrease when compared to its expression in PBMCs, starting from Day 18. In conclusion, PMNs do not respond earlier to the conceptus stimulus, and ISG15 and OAS1 expression in both PMNs and PBMCs can be used as a suitable marker for pregnancy diagnosis on Days 18 and 20. In addition, gestational status did not affect IFNAR1 and IFNAR2 expression, but IFNAR2 showed a distinct response between PMNs and PBMCs of pregnant heifers.

Increased pregnancy rate in beef heifers resynchronized with estradiol at 14 days after TAI.

We aimed to evaluate the treatment with estradiol benzoate (EB) or 17ß-estradiol (E2) associated with progesterone (P4) for resynchronization of ovulation 14 days after timed artificial insemination (TAI). In Experiment 1 (Exp. 1), Nelore heifers were submitted to TAI (D0). On D14, the animals received an intravaginal P4 device and were randomly assigned to one of three groups: control (no treatment; n = 17); EB (1  mg EB; n = 17); and E2+P4 (1 mg E2 + 9 mg P4; n = 18). Ultrasonography evaluations were performed daily from D14 to D22 to map follicular and luteal dynamics. On D22, the P4 devices were removed and non-pregnant (NP) animals were determined using corpus luteum blood flow Doppler ultrasonography. In Exp. 2, 1295 beef heifers were resynchronized and randomly allocated to the same experimental groups as described in Exp. 1. On D22, the largest follicle (LF) was measured in NP and a second TAI was performed on D24. In a subset of heifers (n = 337), an estrus detection patch was used between D22 and D24 to monitor estrus expression and the LF was measured at D24. Confirmatory diagnosis of pregnancy was performed between D37-67 and D43-67 after first and second TAI, respectively. In Exp 1, the proportion of heifers with a synchronized follicular wave emergence (from 3 to 5 days after treatment) was greater (P < 0.05) in the EB group (93.8%) than in the control (62.5%) and E2+P4 (64.7%) groups. Structural luteolysis occurred earlier (P < 0.05) in the EB and E2+P4 groups than in the controls. The pregnancy rate after first TAI did not differ (P > 0.1) among the groups at D22 and at confirmatory diagnosis in both experiments. In Exp 2, the potential pregnancy loss between D22 and D37-67 was similar (P > 0.1) in the control (19% [36/185]), EB (15% [28/182]) and E2+P4 (15% [28/184]) groups. The LF diameter (mm) on D22 was greater (P < 0.05) in the control group (11.9 ± 0.1) than in EB (11.3 ± 0.1) and E2+P4 (11.5 ± 0.1). No difference (P > 0.1) was observed in the proportion of heifers detected in estrus, but LF growth rate (mm/day) between D22 and D24 was greater (P < 0.05) in EB group (0.9 ± 0.08) than in control (0.6 ± 0.07) and E2+P4 (0.7 ± 0.09) groups. The pregnancy rate for the second TAI was greater (P < 0.05) in the EB group (47% [94/200]) than in the control (37% [76/203]), but did not differ (P > 0.1) from the E2+P4 group (43% [93/214]). In conclusion, the treatment with 1 mg EB or 1 mg E2 + 9 mg P4 at 14 days post-TAI anticipates luteolysis in NP heifers but does not compromise pregnancy. The EB treatment induces a new synchronized follicle wave emergence and increases the pregnancy rate of resynchronized NP heifers.

Snakebites in southern Minas Gerais state, Brazil

In Brazil, more than 80 per cent of venomous snakebites are caused by Bothrops and about 10 per cent by Crotalus. This study evaluated 133 reported cases that occurred between 1994 and 1996 in the 52 municipalities covered by the Pouso Alegre Regional Health Center in southern Minas Gerais State. Most of the patients were male (89.5 per cent). The most frequently attacked age bracket was that of people in their twenties, and the most frequently bitten anatomical regions were the lower limbs (77.7 per cent), principally the feet (34.6 per cent). Of the 124 cases stating the snake genus, 62.9 per cent were caused by Crotalus and 37.1 per cent by Bothrops. The conclusion of this study is that although the epidemiology of snakebites in Minas Gerais State is similar to other regions of the country, the percentage of Crotalus bites is much higher