C. A. M. Silva

Universidade Federal de Santa Maria, Santa Maria da Boca do Monte, Rio Grande do Sul, Brazil

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Publications (11)7.12 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Bovine milk samples were collected from milk tanks (n = 69) and from individual cows (n = 3,517) on specialized (S, n = 3), partially specialized (PS, n = 5) and nonspecialized (NS, n = 7) production systems. Compositions, somatic cell count (SCC) and urea nitrogen content were analyzed for the different production systems and all the four seasons. Data were compared to the ranges allowed by the Federal Normative Instruction 51/2002 (IN51) for South Brazil from May 2009 to June 2010. Forty-two percent (n = 29/69) of all milk samples obtained from tanks and 11% of the individual samples in the three production systems met IN51 standards. Of the collected tank samples, 70% (n = 14/20), 39% (n = 9/23) and 23% (n = 6/26) of the S, PS and NS systems, respectively, met IN51 criteria. These data indicate that evaluation of individual samples yields a lower percent of conformity with IN51 standards than tank samples. This implies that the milk from healthy cows may dilute the higher SCC of diseased cows, suggesting that tank samples are not accurate for a confident milk quality indicator. The fat, protein and total solids content in the tank samples were similar among the three production systems. Average lactose and urea nitrogen content in tank samples were similar between seasons. In contrast, the average SCC was above the IN51 standard in the tank and individual samples during the fall. Urea nitrogen content average was highest (P < 0.001) in the specialized production system, both in the tank and individual samples. The evaluation of individual samples may improve nutritional support of the specialized system.
    Arquivos do Instituto Biológico. 12/2012; 79(4):485-493.
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    [show abstract] [hide abstract]
    ABSTRACT: Bovine milk samples were collected from milk tanks (n = 69) and from individual cows (n = 3,517) on specialized (S, n = 3), partially specialized (PS, n = 5) and nonspecialized (NS, n = 7) production systems. Compositions, somatic cell count (SCC) and urea nitrogen content were analyzed for the different production systems and all the four seasons. Data were compared to the ranges allowed by the Federal Normative Instruction 51/2002 (IN51) for South Brazil from May 2009 to June 2010. Forty-two percent (n = 29/69) of all milk samples obtained from tanks and 11% of the individual samples in the three production systems met IN51 standards. Of the collected tank samples, 70% (n = 14/20), 39% (n = 9/23) and 23% (n = 6/26) of the S, PS and NS systems, respectively, met IN51 criteria. These data indicate that evaluation of individual samples yields a lower percent of conformity with IN51 standards than tank samples. This implies that the milk from healthy cows may dilute the higher SCC of diseased cows, suggesting that tank samples are not accurate for a confident milk quality indicator. The fat, protein and total solids content in the tank samples were similar among the three production systems. Average lactose and urea nitrogen content in tank samples were similar between seasons. In contrast, the average SCC was above the IN51 standard in the tank and individual samples during the fall. Urea nitrogen content average was highest (P < 0.001) in the specialized production system, both in the tank and individual samples. The evaluation of individual samples may improve nutritional support of the specialized system.
    Arquivos do Instituto Biológico 10/2012; 79(4):485.
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    ABSTRACT: The objective was to determine the effects of exogenous prostaglandin F(2α) (PGF), with or without progesterone treatment, on first ovulation in prepubertal heifers. We tested the hypothesis that PGF has a luteolysis-independent ovulatory effect in cattle. Crossbred Angus heifers (12 to 14 mo old, 250 kg body weight, and an average body condition score of 3 out of 5) were examined by transrectal ultrasonography on two occasions, 11 days apart. Heifers in which a CL was not detected at either examination were considered prepubertal. Heifers were assigned randomly to three experimental groups: (1) PG group (N = 14); heifers were treated with a PGF analog (500 μg cloprostenol im) 5 days after the emergence of a spontaneous (i.e., naturally occurring, noninduced) follicular wave; (2) PPG group (N = 12); heifers were given an intravaginal progesterone-releasing insert (CIDR; Pfizer Animal Health, Montreal, QC, Canada), and a follicular wave was induced with 50 mg of progesterone + 2 mg of estradiol benzoate im, and a PGF analog was given at the time of CIDR removal, on Day 5 of the follicular wave (on average, 8.6 ± 0.5 days after CIDR insertion); and (3) control group heifers were given no treatment (N = 14). Heifers were examined daily by transrectal ultrasonography from the start of the experiment to confirmation that ovulation had occurred, or to 5 days after PGF injection (PG and PPG groups) or until dominant follicles of the next follicular wave reached 8 mm (control group). The percentage of heifers that ovulated within 10 days after wave emergence was higher in PPG (10/12; 83.3%) and PG (11/14; 78.5%) groups than in control (1/14; 7.1%; P < 0.0001). Ovulations occurred 69.6 ± 6 h and 93.8 ± 5 h after PGF treatment in PPG and in PG groups, respectively, whereas only one heifer in the control group ovulated 96 h after Day 5 of follicular wave (P = 0.13). In summary, PGF treatment was associated with ovulation in prepubertal heifers whether or not exogenous progesterone was used as a pretreatment. The hypothesis that PGF will induce ovulation by a luteolysis-independent mechanism was supported.
    Theriogenology 08/2012; 78(7):1578-82. · 2.08 Impact Factor
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    ABSTRACT: Ultrasound-guided follicular aspiration was performed in 26 Criollo crossbred mares, followed by the evaluation of ultrasonographic images of the Corpus luteum (CL) that was formed after puncture of follicles of different diameters (Group 25-29 mm; Group 30-35 mm and Group >35 mm). Serum progesterone (P(4) ) concentrations were measured to determine CL function. The size of the CL was measured and the CL was classified based on the following echoscore: 1- anechoic tissue; 2- poorly defined luteal structure with low echogenicity; 3- echogenicity analogous to a luteal structure. The proportion of aspirated follicles that formed a functional CL (based on P(4) concentration) 8 days after aspiration was 57.1% (4/7; CL size 25-29 mm), 75.0% (6/8; CL size 30-35 mm) and 72.7% (8/11; CL size >35 mm), respectively (p > 0.05). The echographic scores of aspirated follicles (indicating the presence or absence of a CL) were consistent with serum P(4) concentrations (p < 0.0001). Of 26 aspirations, 18 resulted in luteal function confirmed by increased progesterone concentrations ([P(4) ] > 1.0 ng/ml); 17 of these mares (94.4%) had an echoscore (2-3) compatible with luteinization (p = 0.0372). Eight days after aspiration, serum [P(4) ] > 2.0 ng/ml was associated with high (p = 0.0056) CL echoscore (3) in 15 of 17 mares (88.2%). The echoscore used in this study was valuable as a screening test to detect the presence of a functional CL after aspiration. An echoscore of 3 served as a practical and efficient method to confirm luteinization.
    Reproduction in Domestic Animals 08/2011; 47(2):288-92. · 1.39 Impact Factor
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    ABSTRACT: The objective of this study was to determine the effect of fetal calf serum (FCS) on the quality of in vitro produced bovine embryos. Cumulus oocyte-complexes (COCs, n = 2 449) recovered by ovum pick-up from Bos taurus indicus donors were randomly assigned to experimental groups. Sperm selected by Percoll gradient was used for in vitro fertilization (insemination = Day 0). In Experiment 1 (n = 1 745 COCs), zygotes were cultured in vitro in Synthetic Oviduct Fluid + 4 mg/mL of bovine serum albumin (BSA), or BSA + 2% FCS (BSA+FCS). In Experiment 2 (n = 704 COCs), the COCs were cultured in SOF + BSA, BSA + 2% FCS, or BSA + 2% FCS on D4 (BSA + FCSD4). In Experiment 1, blastocyst yield (51%) and Quality I blastocysts (41%) at Day 7 were higher (P < 0.05) in the BSA + FCS treatment than in BSA (42 and 30%, respectively). In Experiment 2, blastocyst yield was higher (P < 0.05) in the BSA+FCS (47%) treatment. Quality I blastocyst yield was higher (P < 0.05) for BSA + FCS (34%) and BSA+FCSD4 (32%) compared to the BSA treatment (20%). A total of 820 embryos were transferred, with no significant differences among groups in pregnancy rates. In conclusion, in vitro culture in SOFaaci + BSA + FCS enhanced blastocyst yield and Quality I blastocysts; adding FCS to the culture medium increased the efficiency of IVP of bovine embryos.
    Theriogenology 10/2010; 75(3):429-33. · 2.08 Impact Factor
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    ABSTRACT: Ultrasonic-guided transvaginal follicle aspiration was performed in 58 crossbreed mares in order to determine whether aspiration of various dominant follicle diameters resulted in luteal tissue capable of producing progesterone (P(4)). The mares were randomly assigned to three groups according to follicular diameter (25-29 mm; 30-35 mm and >35 mm). Mares that had ovulations naturally served as controls. The serum progesterone (P(4)) concentrations in the aspirated mares were greater (P < 0.0001; r(2) = 0.6687; CV = 21.52) in mares with natural ovulation compared to mares with aspirated follicles regardless of groups. Serum P(4) concentration in aspired mares with follicular diameter of 25-29 mm declined 0.365 ng/ml/day (P = 0.0065) from the day of aspiration (D0) up to D8. In mares with follicle diameter of 30-35 mm, serum P(4) concentration increased (0.258 ng/ml/day; P = 0.001), as well as in the mares with follicles >35 mm diameter (0.481 ng/ml/day; P < 0.0001), and in mares with natural ovulation (1.236 ng/ml/day; P < 0.0001). Out of the 25 mares with follicular aspirations that formed Corpora hemorragica (P(4) >1 ng/ml), 23 (92%) had greater (>2 ng/ml) serum P(4) concentrations on Day 8 after aspiration. Of these 23 mares, 75% were in the 25-29 mm group, 9/10 (90%) in the 30-35 mm group, and 11/11 (100%) of the mares in the >35 mm follicular diameter group had luteinization (P(4) >2 ng/ml). These results suggest that a functional Corpus luteum can be induced in mares using follicular aspiration and that a minimum 35 mm follicular diameter is needed to reach a progesterone serum concentration compatible with that of a Corpus luteum produced by natural ovulation.
    Animal reproduction science 05/2010; 119(1-2):56-62. · 1.56 Impact Factor
  • Reproduction Fertility and Development - REPROD FERT DEVELOP. 01/2010; 22(1).
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    ABSTRACT: The aim of this research was to determine the influence of Neospora caninum (NC) infection on reproductive parameters of Holstein dairy cows. The study was performed at 32 farms in the south of Brazil, latitude 27◦30�S to 31◦S and longitude 51◦30�Wto 55◦30W. Farms included in this study met Epidemiology/Diseases Reproduction, Fertility and Development 253 rigorous vaccination schedule for infectious bovine rhinotracheitis, bovine viral diarrhea virus, leptospirosis, and brucellosis. Blood samples collected from the dairy cowswere submitted to serologic testing by an indirect fluorescent antibody test (IFAT) andwere distributed into 2 groups: seropositive (GP; n=160) and seronegative (GN; n=558). The dogs (n=51) of the farms were tested by IFAT. After abortion, fetuses were frozen at −80◦C and submitted to PCR detection of NC in tissues. Seropositive cows that aborted were also tested by IFAT. Pregnancies of GP and GN cows were monitored by periodic ultrasound exams. After parturition or abortion all cows in GP and GN groups were submitted to gynecological exams. Cows that developed disease (clinical mastitis, metabolic disease, or laminitis) after parturition or abortionwere excluded from the analysis to prevent any distortion of data. Farmswere divided into 3 categories according to production technology, specifically, average milk production per cowper lactation: high (≥25 kg), medium (15–25 kg), and low(<15 kg). Datawas analyzed byANOVAusing SAS® software (SAS Institute, Cary, NC, USA) at a level of5% significance and Student’s t-test for average reproductive parameters.The alternative hypothesis of the studywas that at least 1 reproductive parameter was influenced in GP after abortion compared with GN cows that aborted. The null hypothesis was that there was no influence of NC antibody titer on reproductive parameters.The prevalence of antibody forNCin dairy cowswas 24.48%.Therewas no prevalence difference among production systems (P >0.05). The prevalence in dogs was 48.6% and did not differ among production systems. Fifty-nine (41.37%) NC-seropositive cows aborted. This differs significantly from the seronegative cow abortion rate (n=17; 2.6%; P <0.001). Occurrence of retained fetal membranes (RFM), endometritis, absence of uterine infection after abortion, and days between abortion and first estrus can be observed in Table 1. Abortion occurred between the fifth and eighth month of pregnancy. Occurrence of RFM was more frequent in cows that were seropositive. The period between abortion and first estrus was 79.06 v. 65.8 days for seropositive and seronegative groups, respectively, which differed significantly (P <0.001). The results suggest that the higher occurrence of RFM after abortion in dairy NC-seropositive cows affects uterine involution, resulting in a delay of ovarian activity.
    Reproduction Fertility and Development - REPROD FERT DEVELOP. 01/2010; 22(1).
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    ABSTRACT: The Criollo horse industry requires more efforts toward a better understanding of breed characteristics and physiology; few studies have been conducted in Criollo horses to fulfill this demand. Toward this aim, 70 Criollo mares (between 3 and 28 years of age) underwent physiologic evaluation of the length of gestation, occurrence of foal heat, and interval to postpartum ovulation. Gestation length in the 70 mares was 335.6 ± 10.5 days, varying from 312 to 364 days. The mean (±SD) interval from parturition to first ovulation of 42 mares that foaled between September and December of 2005 and 2006 was 19.9 ± 14.0 days. Eighty-three percent of the mares had an interval to foal heat ovulation shorter than 20 days (35/42). The mean (±SD) parturition to ovulation interval of these mares was 14.2 ± 3.0 days.
    Journal of Equine Veterinary Science - J EQUINE VET SCI. 01/2007; 27(12):531-534.
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    ABSTRACT: For in vitro embryo production following ovum-pick-up groups with different number of oocytes and volume of medium may be required to maintain an individualized production of each cow. Bovine oocytes were randomly allocated in a 3x3 factorial design in order to evaluate the effect of number of oocytes (5, 10 and 20) and maturation medium volume ratios (1:1, 1:5 and 1:10 oocyte/μl) on embryo production. After 22- 24h maturation in TCM-199, in vitro fertilization was performed in FERT-TALP medium, for 18-22h. Groups of 20 presumptive zygotes were cultured in 200μl of SOF medium for eight days. There was no effect of interaction between number of oocytes and volume of maturation medium (P>0.05) on embryo development. Cleavage rates were not affected either by number of oocytes nor by volume of medium (P>0.05). Blastocyst rates on D7 (19, 26 and 28%; D0=day of fertilization) and D9 (23, 33 and 33%) were lower (P0.05) for ratios 1:1, 1:5 and 1:10 oocytes/μl, respectively. Hatching rate with a 1:1 volume ratio (26%) was lower (P
    01/2005;
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    ABSTRACT: Sixty seven healthy horses (21 jumpers, 23 thoroughbreds and 23 criollo horses) underwent ul- trasound investigation of their palmar metacarpal re- gion. Echogenicity, shape, position, boundaries, fi- ber alignment and cross-sectional area of the super- ficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT) and accessory ligament of the DDFT (AL-DDFT) were assessed at 7 zones of the metacar- pus (McIII). Cross-sectional ultrasound images of the SDFT, DDFT and AL-DDFT showed a fine arrange- ment of dots of homogeneous texture and longitudi- nal images showed the linear fiber arrangement. Dif- ferences found in the CSA of the flexor tendons be- tween breeds indicate the need for reference values. Jumpers had higher mean CSA followed by thorough- breds and criollos. No differences were found between colateral values so that they can be used for com- parison. The relationship between CSA of the SDFT and the DDFT showed less variation between breeds than the CSA of the tendons and its use may turn diagnosis of size differences more precise.