Prostaglandin F2α influences pre-ovulatory follicle characteristics and pregnancy per AI in anovular dairy cows.

Objectives were to determine the effects of a dose of PGF2α administered 2 days before timed artificial insemination (AI) on LH pulsatility, characteristics of the pre-ovulatory follicle, and pregnancy per artificial insemination (P/AI) in anovular dairy cows, particularly in cows not subjected to hyperthermia. In experiment 1, 2,011 lactating Holstein cows had ovaries scanned by ultrasound to determine corpus luteum (CL) presence and only those without a CL in two consecutive exams were enrolled (n = 437). Cows had the estrous cycle synchronized with an estradiol-progesterone based protocol starting on experiment Day -11 and timed AI on Day 0. Cows were assigned randomly to receive a single dose of 25 mg of PGF2α as dinoprost on Day -4 (1PGF, n = 222) or two doses of 25 mg each of PGF2α, one on Day -4 and one on Day -2 (2PGF, n = 215). Rectal temperatures were evaluated on the day of AI and 7 days later and cows were classified as being normothermic (<39.1 °C) or hyperthermic (≥39.1 °C). Ovulatory responses and P/AI were determined. In experiment 2, cows with regressed CL were exposed to low concentrations of progesterone and then randomly assigned to the same estrous synchronization protocol and treatments, 1PGF (n = 28) and 2PGF (n = 28). Blood was sampled and analyzed for concentrations of progesterone, and for concentrations of LH and 13,14-dihydro-15-keto-PGF2α metabolite (PGFM) every 15 min starting 1 h before to 6 h after treatments and then every 2 h from 12 to 59 h after treatments. The pre-ovulatory follicle was aspirated 44 h after treatments and concentrations of estradiol quantified. In experiment 1, treatment of anovular cows with a second dose of PGF2α increased P/AI in normothermic cows (19.8 [18/91] vs. 38.8% [31/80]), but not in hyperthermic cows. Synchronization was not affected by treatment, but it was greater for normothermic than hyperthermic cows (87.1 [149/171] vs. 77.8% [207/266]). When only synchronized cows were evaluated, the same responses were observed; treatment with 2PGF increased P/AI compared with 1PGF in normothermic cows (23.1 [18/78] vs. 43.7% [31/71]), but not in hyperthermic cows. In experiment 2, administration of 25 mg of dinoprost in 2PGF resulted in concentrations of PGFM 26-fold greater than 1PGF in the first 6 h after treatment (48 vs. 1,242 pg/mL). Cows receiving 2PGF had smaller basal LH concentration (0.57 vs. 0.46 ng/mL) and less frequent LH pulses (4.5 vs. 3.9 pulses/6 h), but duration of the LH surge was longer for 2PGF than 1PGF (13.1 vs. 15.5 h). Treatment with 2PGF increased the diameter and volume of the pre-ovulatory follicle, and concentration of estradiol (115 vs. 262 ng/mL) and total follicular estradiol content (124 vs. 505 ng) compared with 1PGF. Collectively, these results suggest that PGF2α has a role in fertility of anovular cows that is unrelated to its luteolytic effect.

Effects of level of dietary cation-anion difference and duration of prepartum feeding on performance and metabolism of dairy cows.

The objectives were to evaluate the effects of feeding diets with 2 levels of negative dietary cation-anion differences (DCAD) during the last 42 or 21 d of gestation on performance and metabolism in dairy cows. The hypothesis was that extending feeding from 21 to 42 d and reducing the DCAD from -70 to -180 mEq/kg of dry matter (DM) would not be detrimental to performance. Holstein cows at 230 d of gestation were blocked by parity prepartum (48 entering their second lactation and 66 entering their third or greater lactation) and 305-d milk yield, and randomly assigned to 1 of 4 treatments arranged as a 2 × 2 factorial. The 2 levels of DCAD, -70 or -180 mEq/kg of DM, and 2 feeding durations, the last 21 d (short) or the last 42 d (long) prepartum resulted in 4 treatments, short -70 (n = 29), short -180 (n = 29), long -70 (n = 28) and long -180 (n = 28). Cows in the short treatments were fed a diet with DCAD of +110 mEq/kg of DM from -42 to -22 d relative to calving. After calving, cows were fed the same diet and production and disease incidence were evaluated for 42 d in milk, whereas reproduction and survival was evaluated for 305 d in milk. Blood was sampled pre- and postpartum for quantification of metabolites and minerals. Reducing the DCAD linearly decreased prepartum DM intake between -42 and -22 d relative to calving (+110 mEq/kg of DM = 11.5 vs. -70 mEq/kg of DM = 10.7 vs. -180 mEq/kg of DM = 10.2 ± 0.4), and a more acidogenic diet in the last 21 d of the dry period reduced intake by 1.1 kg/d (-70 mEq/kg of DM = 10.8 vs. -180 mEq/kg of DM = 9.7 ± 0.5 kg/d). Cows fed the -180 mEq/kg of DM diet had increased concentrations of ionized Ca in blood on the day of calving (-70 mEq/kg of DM = 1.063 vs. -180 mEq/kg of DM = 1.128 ± 0.020 mM). Extending the duration of feeding the diets with negative DCAD from 21 to 42 d reduced gestation length by 2 d (short = 277.2 vs. long = 275.3 d), milk yield by 2.5 kg/d (short = 40.4 vs. long = 37.9 ± 1.0 kg/d) and tended to increase days open because of reduced pregnancy per artificial insemination (short = 35.0 vs. long = 22.6%). Results suggest that increasing the duration of feeding diets with negative DCAD from 21 to 42 d prepartum might influence milk yield and reproduction of cows in the subsequent lactation, although yields of 3.5% fat- and energy-corrected milk did not differ with treatments. Reducing the DCAD from -70 to -180 mEq/kg of DM induced a more severe metabolic acidosis, increased ionized Ca concentrations prepartum and on the day of calving, and decreased colostrum yield in the first milking, but had no effects on performance in the subsequent lactation. Collectively, these data suggest that extending the feeding of an acidogenic diet beyond 21 d is unnecessary and might be detrimental to dairy cows, and a reduction in the DCAD from -70 to -180 mEq/kg of DM is not needed.

Melatonin reduces apoptotic cells, SOD2 and HSPB1 and improves the in vitro production and quality of bovine blastocysts.

Effects of adding different concentrations of melatonin (10-7 , 10-9 and 10-11  M) to maturation (Experiment 1; Control, IVM + 10-7 , IVM + 10-9 , IVM + 10-11 ) and culture media (Experiment 2; Control, IVC + 10-7 , IVC + 10-9 , IVC + 10-11 ) were evaluated on in vitro bovine embryonic development. The optimal concentration of melatonin (10-9  M) from Experiments 1-2 was tested in both maturation and/or culture media of Experiment 3 (Control, IVM + 10-9 , IVC + 10-9 , IVM/IVC + 10-9 ). In Experiment 1, maturated oocytes from Control and IVM + 10-9 treatments showed increased glutathione content, mitochondrial membrane potential and percentage of Grade I blastocysts (40.6% and 43%, respectively). In Experiment 2, an increase in the percentage of Grade I blastocysts was detected in IVC + 10-7 (43.5%; 56.7%) and IVC + 10-9 (47.4%; 57.4%). Moreover, a lower number and percentage of apoptotic cells in blastocysts were observed in the IVC + 10-9 group compared to Control (3.8 ± 0.6; 3.6% versus 6.1 ± 0.6; 5.3%). In Experiment 3, the IVC + 10-9 treatment increased percentage of Grade I blastocysts with a lower number of apoptotic cells compared to IVM/IVC + 10-9 group (52.6%; 3.0 ± 0.5 versus 46.0%; 5.4 ± 1.0). The IVC + 10-9 treatment also had a higher mRNA expression of antioxidant gene (SOD2) compared to the Control, as well as the heat shock protein (HSPB1) compared to the IVM + 10-9 . Reactive oxygen species production was greater in the IVM/IVC + 10-9 treatment group. In conclusion, the 10-9  M concentration of melatonin and the in vitro production phase in which it is used directly affected embryonic development and quality.

Preantral follicle density in ovarian biopsy fragments and effects of mare age.

The aims of the present study were to: (1) evaluate preantral follicle density in ovarian biopsy fragments within and among mares; (2) assess the effects of mare age on the density and quality of preantral follicles; and (3) determine the minimum number of ovarian fragments and histological sections needed to estimate equine follicle density using a mathematical model. The ovarian biopsy pick-up method was used in three groups of mares separated according to age (5-6, 7-10 and 11-16 years). Overall, 336 preantral follicles were recorded with a mean follicle density of 3.7 follicles per cm2. Follicle density differed (P<0.05) among animals, ovarian fragments from the same animal, histological sections and age groups. More (P<0.05) normal follicles were observed in the 5-6 years (97%) than the 11-16 years (84%) age group. Monte Carlo simulations showed a higher probability (90%; P<0.05) of detecting follicle density using two experimental designs with 65 histological sections and three to four ovarian fragments. In summary, equine follicle density differed among animals and within ovarian fragments from the same animal, and follicle density and morphology were negatively affected by aging. Moreover, three to four ovarian fragments with 65 histological sections were required to accurately estimate follicle density in equine ovarian biopsy fragments.

Number and density of equine preantral follicles in different ovarian histological section thicknesses.

Regardless of species, advances in preantral follicle culture and cryopreservation and transplant of ovarian tissue techniques are dependent on the number and density of preantral follicles in the ovary. This study tested the effect of different histological section thicknesses on number, classification, and density of equine preantral follicles. An ovarian fragment was obtained from 5- to 10-year-old mares (n = 14) after slaughter, and each fragment was submitted to three histological section thickness treatments: 3, 5, and 7 µm. The area (cm(2)) of each ovarian fragment was measured, and the sections were evaluated by light microscopy. The percentage of morphologically normal follicles (89%) was similar (P > 0.05) among primordial, transitional, and primary follicles and also among histological section thicknesses. A greater (P < 0.05) number of preantral follicles per histological section were seen in the 7-µm (8.0 ± 2.2) than that in the 3-µm (3.4 ± 0.7) treatment. Furthermore, a linear regression analysis reported that the number of preantral follicles increased (P < 0.05) when a thicker section treatment was used. However, no association (P > 0.05) between follicular density and treatment was observed. The mean number of preantral follicles per fragment (45.3 ± 18.8) and the follicular density (3.0 ± 0.5 follicles per cm(2)) were different (P < 0.05) among mares. In conclusion, this study on equine preantral follicles reported that (1) a 7-µm histological section thickness might be recommended because it allowed identification of a greater number of preantral follicles per sample, (2) a large individual variation in follicle population and density was detected regardless of histological section thickness, and (3) mares have a low number and density of preantral follicles when compared with those reported for other species.

Excretion of Brucella abortus vaccine B19 strain during a reproductive cycle in dairy cows

This paper aimed to determine the excretion period of B19 vaccine strain during a complete reproductive cycle (from estrus synchronization, artificial insemination, pregnancy and until 30 days after parturition) of dairy cows from 3 to 9 years old that were previously vaccinated from 3 to 8 months. Three groups were monitored with monthly milk and urine collection during 12 months: G1 with seven cows from 3 to 4 years old; G2 with three cows from 5 to 6 years old; and G3 with four cows from 7 to 9 years old. Urine and milk samples were submitted to bacteriological culture and urine and PCR reactions for detection of Brucella spp. and PCR-multiplex for B19 strain identification. Ring test (RT) was also performed in the milk samples, and serum samples were tested by buffered acidified plate antigen test (BAPA). All animals were serologically negative at BAPA and Brucella spp. was not isolated from both urine and milk samples. RT revealed 13/210 (6.2%) positive milk samples. PCR reactions detected DNA of Brucella spp. in 86/420 (20.5%) samples. In urine it was found a significantly higher frequency (35.2%; 74/210) than in milk (5.7%; 12/210), more frequently from the estrus to 150 days of pregnancy and after parturition (6.7%; 10/150), and from 150 days of pregnancy to parturition (3.4%; 2/60), and they were all identified as B19 strain. In three groups, intermittent excretion of B19 strain was detected mainly in urine samples, which confirmed its multiplication and persistence in cows for until 9 years.

Excretion of Brucella abortus vaccine B19 strain during a reproductive cycle in dairy cows.

This paper aimed to determine the excretion period of B19 vaccine strain during a complete reproductive cycle (from estrus synchronization, artificial insemination, pregnancy and until 30 days after parturition) of dairy cows from 3 to 9 years old that were previously vaccinated from 3 to 8 months. Three groups were monitored with monthly milk and urine collection during 12 months: G1 with seven cows from 3 to 4 years old; G2 with three cows from 5 to 6 years old; and G3 with four cows from 7 to 9 years old. Urine and milk samples were submitted to bacteriological culture and urine and PCR reactions for detection of Brucella spp. and PCR-multiplex for B19 strain identification. Ring test (RT) was also performed in the milk samples, and serum samples were tested by buffered acidified plate antigen test (BAPA). All animals were serologically negative at BAPA and Brucella spp. was not isolated from both urine and milk samples. RT revealed 13/210 (6.2%) positive milk samples. PCR reactions detected DNA of Brucella spp. in 86/420 (20.5%) samples. In urine it was found a significantly higher frequency (35.2%; 74/210) than in milk (5.7%; 12/210), more frequently from the estrus to 150 days of pregnancy and after parturition (6.7%; 10/150), and from 150 days of pregnancy to parturition (3.4%; 2/60), and they were all identified as B19 strain. In three groups, intermittent excretion of B19 strain was detected mainly in urine samples, which confirmed its multiplication and persistence in cows for until 9 years.

The effect of offering an energy and protein supplement to grazing Canchim beef cows either postpartum or both pre- and postpartum on lipid blood metabolites and folliculogenesis.

This study was designed to evaluate the effect of nutritional supplementation offered during the pre- and postpartum periods on serum cholesterol, triglycerides and total lipids of Canchim beef cows and their relationship with folliculogenesis. Thirty cows with predicted calving date between September and October, kept in pastures of Brachiaria brizantha cv. Marandú together with their calves, were randomly distributed into three experimental groups: the first received only a mineral mixture (Control Group, CG); the second group received a concentrate with 16%crude protein/kg dry matter (DM) and 3000 kcal digestible energy/kg DM offered for 45 days prepartum and 120 days postpartum (PREG); the third group received the concentrate from parturition until the 120th day postpartum (POSG). Consumption was estimated at 1% of body weight, and each cow received approximately 4.0 kg/day (fresh weight) of supplement. Blood samples were taken and an ultrasound examination of the ovaries was performed twice a week until the 60th day postpartum. The body condition score (BCS) and the weight of the cows were recorded at 15-day intervals from calving until the 60th day postpartum. Data are presented as mean+/-SEM. Mean weight and BCS at calving were, respectively, 448+/-54.9 kg and 6.2+/-0.25 (PREG); 432+/-71.1 kg and 5.5+/-0.69 (POSG); and 434+/-66.4 kg and 5.5+/-0.69 (CG). Total cholesterol (TC), triglycerides (TRIG) and total lipids (TLIP) were measured using colorimetry until the 60th day postpartum. TC averages were PREG 186+/-62.6 mg/dL, POSG 159+/-43.1mg/dL and CG 133+/-35.1mg/dL (P<0.05). For TRIG, the means were PREG 29+/-11.3mg/dL (P<0.05), POSG 24+/-8.1mg/dL and CG 26+/-12.1mg/dL (P>0.05). Serum concentrations of TLIP were PREG 588+/-145.6 mg/dL, POSG 512+/-137.6 mg/dL and CG 452+/-122.4 mg/dL (P<0.05). The first dominant follicle (DF) was identified on Day 21+/-10.3 (PREG), 36+/-28.5 (POSG) and 51+/-32.8 (CG) after calving. The difference between PREG and CG was significant (P<0.05). TC was positively correlated with the calving to first estrus interval (P<0.05). Results showed that nutritional supplementation before parturition assured good body condition at calving and suggested that it was effective at increasing cholesterol availability to maintain ovarian follicle function and to favor earlier resumption of ovarian activity.

Granular Vulvovaginitis Syndrome in Nelore pubertal and post pubertal replacement heifers under tropical conditions: role of Mycoplasma spp., Ureaplasma diversum and BHV-1.

In order to determine the role of Mycoplasma spp, Ureaplasma diversum and BHV-1 as causal agents of Granular Vulvovaginitis Syndrome in Nelore heifers raised under tropical conditions and based on the hypothesis that stressful conditions during puberty or breeding season would be a determinant factor for the infection, 340 heifers not vaccinated against BHV-1 were divided in Post-pubertal, in the beginning of the first breeding season, and Pubertal heifers. The vaginal lesion score (VLS) Grade 1 to 4 was giving according to lesion area and severity. Vaginal mucus was used to isolate Mycoplasma spp., Ureaplasma diversum and BHV-1. The predominant VLS was 2. No sample was positive for BHV-1; 48% were positive for Mycoplasma spp., Ureaplasma diversum, or both, with predominance of Ureaplasma diversum. Serum neutralization for BHV-1 showed more positive animals in pubertal group (23%); 3 of the paired sera demonstrated seroconversion. These data indicated that post-pubertal and pubertal Nelore heifers raised under extensive conditions are more susceptible to Mycoplasma spp. and Ureaplasma diversum. The hypothesis that the stress of pubertal period could lead to an acute vaginal infection by HBV-1 was not proofed.

Effects of biostimulation and nutritional supplementation on pubertal age and pregnancy rates of Nelore heifers (Bos indicus) in a tropical environment.

To determine effects of biostimulation (BIO) and dietary supplementation (BIO+S) on pubertal age and pregnancy rates, Nelore heifers (n=392) were randomly assigned to one of four treatment groups (n=98/group). All animals were in tropical environmental conditions, in the middle-west region of Brazil, grazing in pastures of Brachiaria brizantha, cv. Marandu; Panicum Maximum, cv. Tanzânia and Brachiaria humidícula. The heifers of the BIO group were kept in the presence of bulls while being maintained on pasture; the animals in the BIO+S group were kept in the presence of bulls while being managed on pasture and were fed a diet with greater energy and protein content to produce 0.49 kg of BW gain/day; the animals in control group (the NBIO) were kept away from bulls and under pasture conditions; and the animals in the NBIO+S group were kept away from bulls, were maintained on pasture, and were fed the same diet as the BIO+S group. Heifers were bred at 22-23 months of age, and pregnancy diagnosis was made 45 days after the end of the breeding season. There were differences (P<0.05) between groups regarding pubertal heifers up to 19 months (NPH), final body weight (FBW) and pregnancy rates (P<0.01), with an advantage for the animals in the BIO and BIO+S groups. Although the effect of a diet with greater protein and energy content was not clear in this experiment, the exposure of heifers to a male during the prepubertal period decreased age at the first breeding season, resulting in a significant reduction in age of first pregnancy in Nelore heifers kept under extensive management systems in a tropical environment.

Testosterone concentration in blood serum of buffalo bulls during 24 hours in winter and summer seasons

Concentraçöes de testosterona foram determinadas por radioimunoensaio em 30 amostras de soro sanguíneo obtidas cinco vezes durante 24 horas, de 6 búfalos adultos Jaffarabadi x Mediterrâneo. As amostras foram obtidas durante um dia do inverno e um dia do veräo de 1991. As concentraçöes de testosterona variaram de 0,10 a 1,36 ng/ml no inverno e de 0,10 a 2,454 ng/ml no veräo. Valores máximos foram obtidos às 6,00 horas (0,52 ng/ml) no veräo e 0,82 ng/ml no inverno, ocorrendo entäo duas quedas abruptas, a primeira às 12 horas (0,37 ng/ml) no veräo e 0,21 ng/ml no inverno e a segunda 24 horas (0,17 ng/ml) no veräo e 0,49 ng/ml no inverno. No veräo, níveis mais altos de testosterona sérica foram observados durante o dia