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Featured researches published by J. J. Becerra.


Reproduction in Domestic Animals | 2012

Use of Ultrasound in the Reproductive Management of Dairy Cattle

La Quintela; M. Barrio; A.I. Peña; J. J. Becerra; J. Cainzos; Pg Herradón; C. Díaz

The significant decrease in fertility observed in dairy cattle during the last few decades and increasing requirements by the farmers have made a regular control of reproduction indispensable to urgently identify and solve potential problems affecting reproductive efficiency. Traditionally, the main diagnostic methods used for reproductive control in cattle included rectal palpation, inspection of vaginal discharge and vaginoscopy. Since the 1990 s, the use of ultrasound (US) has become a common diagnostic method as a result of the new advances made in the development of US scans: smaller size, high level of autonomy, high image quality and accessible prices. Ultrasound improves accuracy in the diagnoses of stages of the oestrous cycle, ovarian and uterine pathologies, and pregnancy diagnosis. In addition, it facilitates the diagnosis of alterations during pregnancy (embryo mortality, foetal malformations, etc.) and helps determining foetal sex from day 55 of pregnancy.


Animal Reproduction Science | 2012

Motile sperm subpopulations in frozen-thawed dog semen: changes after incubation in capacitating conditions and relationship with sperm survival after osmotic stress.

A.I. Peña; M. Barrio; J. J. Becerra; La Quintela; Pg Herradón

In this study we investigated the changes that in vitro incubation under capacitating conditions could induce on the motile sperm subpopulations present in frozen-thawed dog semen samples. In addition, cryopreserved dog spermatozoa were exposed to CCM (canine capacitating medium) solutions of 300, 150, 100 and 75 mOsm and the proportions of live spermatozoa with swollen tails were recorded (HOST+). Finally, frozen-thawed dog semen samples were submitted to a second cycle of freezing and thawing and the overall sperm motility, as well as the motile sperm subpopulations structure, was determined. Cryopreserved dog semen samples were structured in four sperm subpopulations with different motility characteristics: Subpopulation (Sp) 1 contained moderately rapid and progressive spermatozoa (25.2 ± 8.5%), Sp 2 included poorly motile and non progressive sperm (15.3 ± 8.1%), Sp 3 was represented by moderately slow non progressive sperm (14.9 ± 5.9%), and Sp 4 contained the most rapid and progressive sperm (20.8 ± 14.7%). After 3h of incubation under capacitating conditions, percentages of spermatozoa assigned to Sp 2 (6.1 ± 3.4%) and 3 (4.9 ± 2.8%) significantly decreased, whereas those assigned to Sp 1 (17.0 ± 11.2%) and 4 (16.2 ± 12.8%) did not significantly change. Significant correlations were found between percentages of HOST+, for the 3 osmolarities tested, and percentages of spermatozoa included in Sp 1 and 4 after 3 h of incubation in capacitating conditions or in Sp 4 after double freezing and thawing. These results indicated that subpopulations with the most rapid and progressive sperm seemed to be highly resistant to in vitro incubation in capacitating conditions and to osmotic stress, suggesting they are likely to be the source of the fertilizing population.


Reproduction in Domestic Animals | 2009

Reproductive Performance of Rabbit Does Artificially Inseminated via Intravaginal Administration of [des‐Gly 10, d‐Ala6]‐LHRH Ethylamide as Ovulation Inductor

La Quintela; A.I. Peña; Vega; J Gullón; C Prieto; M. Barrio; J. J. Becerra; Pg Herradón

This study was aimed to evaluate the reproductive performance of rabbit does artificially inseminated (AI) with a GnRH analogue [des-Gly10, D-Ala6]-LHRH. ethylamide to induce ovulation by intravaginal administration, delivered in the seminal dose. In a preliminary experiment, 39 does were divided into three groups (n = 13) that, at the time of AI, received the following ovulation induction treatments: (i) control group: 20 microg of gonadorelin administered intramuscularly; (ii) 25 microg of the GnRH analogue added to the seminal dose; (iii) 30 microg of the GnRH analogue added to the seminal dose. Fertility did not differ between the three groups (control: 80.6%, group 2: 82.8%, group 3: 73.3%). In a second experiment, a large-scale field trial was conducted to test the use of 25 microg of the GnRH analogue [des-Gly10, D-Ala6]-LHRH ethylamide delivered in the seminal dose (n = 270) against 20 microg of gonadorelin administered intramuscularly. Fertility was higher (p < 0.05) when ovulation was induced by intravaginal administration of the GnRH agonist (91.1% vs 85.6%). Prolificacy or mortality at birth was never affected by the ovulation induction treatments. In a third experiment, two groups of does [control group (n = 39): ovulation was induced using 20 microg of gonadorelin administered intramuscularly; treatment group (n = 40): ovulation was induced using 25 microg of [(des-Gly10, D-Ala6)-LHRH ethylamide added to the seminal dose] were inseminated at 42-day intervals for five successive AI cycles, to test the response to the GnRH agonist after repeated intravaginal administration to the same animals. Fertility and prolificacy were not influenced by the ovulation induction treatment neither there was an interaction between treatment and parity. The last experiment was aimed to determine whether it could be possible to add the GnRH agonist to the semen in the AI Center, just after semen collection and dilution, or it would have to be added in the farm, immediately before AI. Kindling rates did not significantly differ when ovulation was induced by intramuscular injection of gonadorelin (84.5%) or when the GnRH agonist was added to the seminal dose just at the moment (93.8 %) or 24 h before AI (90.4 %), but it was significantly lower when the hormone was added to the semen 32 h before AI (76.3 %). Prolificacy, however, was not influenced by the ovulation induction treatment.


Animal Reproduction Science | 2011

Fetal gender determination by first-trimester ultrasound in dairy cows under routine herd management in Northwest Spain

La Quintela; J. J. Becerra; C.C. Pérez-Marín; M. Barrio; J. Cainzos; Alberto Prieto; C. Díaz; Pg Herradón

Ultrasonography (US) provides detailed visualization of the fetus in early pregnancy in cows, thus allowing for fetal sex determination. The objective of this prospective observational study was to determine the feasibility and accuracy of a single US examination to diagnose fetal sex in dairy cattle under routine reproductive management conditions. For this purpose, 953 Holstein cows at 7-16 weeks of gestation were examined. Gender assignment was performed in 822 cows, while the genitalia could not be clearly visualized in 131 (13.7%) of the fetuses. After calving, it was verified that 99.3% of the diagnoses were accurate. Fetal sex was correctly determined by US in 99.5% of male fetuses and 98.8% of female fetuses. Fetal sex determination was less accurate when conducted before d 55 of gestation. Likewise, it was verified that fetal sex, cow age and ultrasonographic diagnosis section did not have a significant influence (P>0.05) on diagnostic accuracy. With respect to the plane used for diagnosis, the sagittal view was poorly used for early pregnancy diagnosis, whereas the longitudinal and cross-sectional planes were used most frequently. These results demonstrate that US can be routinely applied under farm conditions to accurately determine the fetal sex in cattle between days 51 and 111 of gestation without apparent influence of cow age, US scanning plane or fetal sex. Conversely, days of gestation affected the accuracy and feasibility of US gender determination, showing poorer results when the diagnosis was made before day 55 of gestation.


Reproduction in Domestic Animals | 2003

Studies on the Intracellular Ca2+ Concentration of Frozen–Thawed Dog Spermatozoa: Influence of Equex from Different Sources, Two Thawing Diluents and Post‐thaw Incubation in Capacitating Conditions

A.I. Peña; L López‐Lugilde; M. Barrio; J. J. Becerra; La Quintela; Pg Herradón


Reproduction Nutrition Development | 2004

Ovulation induction in rabbit does submitted to artificial insemination by adding buserelin to the seminal dose

La Quintela; A.I. Peña; Maria Dolores Vega; Julian Gullón; Maria Carmen Prieto; M. Barrio; J. J. Becerra; Francisco Maseda; Pg Herradón


Animal Reproduction Science | 2004

Zona pellucida binding ability and responsiveness to ionophore challenge of cryopreserved dog spermatozoa after different periods of capacitation in vitro

A.I. Peña; M. Barrio; J. J. Becerra; La Quintela; Pg Herradón


Reproduction in Domestic Animals | 2007

Infertility in a Dog due to Proximal Cytoplasmic Droplets in the Ejaculate: Investigation of the Significance for Sperm Functionality In Vitro

A.I. Peña; M. Barrio; J. J. Becerra; La Quintela; Pg Herradón


Reproduction, Fertility and Development | 2011

252 EFFECT OF FOLLICLE-STIMULATING HORMONE ADDITION ON IN VITRO MATURATION AND CLEAVAGE OF ALPACA (VICUGNA PACOS) EMBRYOS

R. L. Condori; W. Huanca; M. Chileno; J. Cainzo; F. Valverde; J. J. Becerra; La Quintela; Pg Herradón


Reproduction, Fertility and Development | 2010

341 IN VITRO MATURATION AND IN VITRO FERTILIZATION OF ALPACA (VICUGNA PACOS) OOCYTES: EFFECT OF TIME OF INCUBATION ON NUCLEAR MATURATION AND CLEAVAGE

W. Huanca; R. L. Condori; J. Cainzos; M. Chileno; La Quintela; J. J. Becerra; Pg Herradón

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Pg Herradón

University of Santiago de Compostela

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A.I. Peña

University of Santiago de Compostela

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La Quintela

University of Santiago de Compostela

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M. Barrio

University of Santiago de Compostela

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J. Cainzos

University of Santiago de Compostela

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L. A. Quintela

University of Santiago de Compostela

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Alberto Prieto

University of Santiago de Compostela

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L Wilfredo Huanca

National University of San Marcos

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W. Huanca

National University of San Marcos

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C. Díaz

University of Santiago de Compostela

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