Andrological characteristics of tropical milking criollo bulls

ABSTRACT Objective: To assess the testicular and semen characteristics in Criollo Lechero Tropical (CLT) bulls in the subhumid Mexican tropics. Design/methodology/approach: Eight bulls were included in the study and distributed in two groups: G1 (n=5): young bulls and G2 (n=3): adult bulls. All bulls were managed under grazing and were evaluated throughout one year. From each bull the following measurements were taken once a month: live weight, body condition score, scrotal circumference, and testicular width, length and volume. Semen was obtained every 3 months via artificial vagina. Semen variables evaluated in each collection were: aspect, volume, mass and individual motility, and sperm concentration and morphology. Results: Live weight and testicular measurements increased linearly during the study in bulls from both groups. All bulls had scrotal circumference larger than the minimum threshold value for cattle and semen of high quality. Study limitations/implications: The low availability of CLT bulls prevented the inclusion of a larger number of animals in the study. This low availability of animals makes it necessary to establish standard values for testicular measurements and semen characteristics in the CLT breed in order to select the best individuals as sires and contribute to its conservation. Findings/conclusions:The CLT bulls had good scrotal circumference and semen quality since a young age and into adulthood. These traits make the CLT bulls an important alternative for livestock breeding in the tropics.Objective: To assess the testicular and semen characteristics in Criollo LecheroTropical (CLT) bulls in the subhumid Mexican tropics.Design/methodology/approach: Eight bulls were included in the study and distributedin two groups: G1 (n=5): young bulls and G2 (n=3): adult bulls. All bulls were managedunder grazing and were evaluated throughout one year. From each bull the followingmeasurements were taken once a month: live weight, body condition score, scrotalcircumference, and testicular width, length and volume. Semen was obtained every 3months via artificial vagina. Semen variables evaluated in each collection were: aspect,volume, mass and individual motility, and sperm concentration and morphology. Results: Live weight and testicular measurements increased linearly during the study inbulls from both groups. All bulls had scrotal circumference larger than the minimumthreshold value for cattle and semen of high quality.Study limitations/implications: The low availability of CLT bulls prevented theinclusion of a larger number of animals in the study. This low availability of animalsmakes it necessary to establish standard values for testicular measurements and semencharacteristics in the CLT breed in order to select the best individuals as sires andcontribute to its conservation.Findings/conclusions: The CLT bulls had good scrotal circumference and semenquality since a young age and into adulthood. These traits make the CLT bulls animportant alternative for livestock breeding in the tropics

COMPARACIÓN DE DOS MÉTODOS DE TRANSFERENCIA DE EMBRIONES EN EL GANADO CRIOLLO LECHERO TROPICAL/Comparison of two embryo transfer methods in the tropical milking criollo cattle

. En el ganado Criollo Lechero Tropical (CLT), se desconoce el mejor método para la criopreservación de sus embriones para transferencia. El objetivo del estudio fue comparar los métodos por curva lenta y vitricación en receptoras CLT puras y mestizas; se realizó en Veracruz (CP) y Guerrero (OG). Los tratamientos se asignaron de forma aleatoria: seis embriones para CLT y cuatro para mestizas por curva lenta, así como cinco en CLT y cinco en mestizas por vitricación para CP. En OG, se destinaron cuatro para curva lenta en CLT y cinco en mestizas; para vitricación, seis en CLT y cinco en mestizas. El análisis de datos se realizó con la prueba de Fisher. No se encontró efecto del método de criopreservación en el porcentaje de gestación (p>0.05) y se obtuvieron 10 y 20 % en CP (p≤0.50), 11 y 27 % en OG (p≤0.375) para curva lenta y vitricación, respectivamente

Effect of cryopreservation of in vitro produced embryos on pregnancy rate of cows transferred at fixed time in the dry tropics

The objective of this study was to determine the effect of cryopreservation (CP) of in vitro produced embryos (EIV) on the pregnancy rate (PR) of cows transferred at fixed time (FTET) in the dry tropics. The experimental design was completely randomized with a 2×2 factorial arrangement. The sample consisted of 280 embryos produced in vitro. The factors were the CP (vitrified and fresh) and the Rural Development District (DDR 01 and 02). The experiment consisted of 70 replicates per treatment: T1) fresh transferred embryos; T2) vitrified embryos; T3) DDR + fresh embryos; and 4) DDR + vitrified embryos. The pregnancy diagnosis was carried out 60 days after embryo transfer. The Xi2 test was used to analyze PR which was the response variable per treatment. PR was higher in fresh-transferred embryos than in vitrified embryos (53.6±4.2 vs 27.1±3.7; P<0.05), and in DDR02 than in DDR01 (47.1±4.2 vs 33.6±3.9; P<0.05). Therefore, the transfer of fresh embryos and the DDR02 had a positive overall effect on PR (40.3%)

Embryo development after ICSI, using spermatozoa from bovine testicular tissue treated with three membrane-destabilizing agents

ABSTRACT Objective: To determine differences in embryo development of bovine oocytes fertilized by frozen/thawed spermatozoa (F/T), or by intracytoplasmic sperm injection (ICSI) using F/T or spermatozoa from fresh (FTT) or cryopreserved testicular tissue (CTT) using three spermatozoa membrane destabilizers. Methods. Treatment (TRT) 1- In vitro fertilization (FIV) with F/T, TRT-2 ICSI with F/T, TRT-3 ICSI with FTT, TRT-4 ICSI with CTT. The spermatozoa membranes were destabilized using Triton X-100 (TX), Lysolecithin (LL) or Heparin--Glutathione (Hep-GSH). Embryo cleavage at 48 h and grade 1 and 2 blastocyst on day 8 post fertilization were recorded. The comparison among main effect means were analyzed based on the least significant difference of Fisher. Results. At D8 there was no difference in percentage of blastocyst formation among ICSI TRTs (F/T 13 ± 3, FTT 6 ± 3 and CTT 6 ± 3 p>0.05), but they were lower than control (FIV 23 ± 5). With Hep-GSH destabilizer, there was a lower cleavage at 48 h than the LL and TX (35± 5, vs 50± 5 and 56± 5 p<0.05). Cleavage at 48 h was better for the ICSI with F/T and LL, while for D8, the best percentage to blastocyst was for TX. Conclusion. It is possible to produce blastocysts using ICSI with spermatozoa obtained from fresh or cryopreserved testicular tissue. Sperm cells treated with TX or LL produced more BL than those treated with Hep-GSH. More experiments using spermatozoa obtained from different sources are necessary to improve embryo development after ICSI. Keywords:  ICSI, Vitrification, Testicular tissue, Oocytes, Bovine, Fertilization.R Objective. To determine the differences in the embryo development of bovine oocytes fertilized with frozen/thawing (F/T) spermatozoa or with the intracytoplasmic sperm injection (ICSI) of F/T, spermatozoa from fresh testicular tissue (FTT), and cryopreserved testicular tissue (CTT), using three spermatozoa membrane-destabilizing agents. Methodology. Four treatments were used. Treatment (TRT-1): In vitro fertilization (IVF) with F/T. TRT-2: ICSI with F/T. TRT-3: ICSI with FTT. TRT-4: ICSI with CTT. The spermatozoa membranes were destabilized with Triton X-100 (TX), Lysolecithin (LL), and Heparin-Glutathione (Hep-GSH). Embryonic division was recorded at 48 h and grade 1 and 2 blastocysts (BL) were recorded 8 days (D8) after the fertilization. The means were compared using Fisher’s least significant difference method. Results. At D8, the blastocysts formation between ICSI treatments (F/T 13 ± 3, FTT 6 ± 3, and CTT 6 ± 3, p>0.05) were lower than control (IVF 23 ± 5). There was a lower cleavage at 48 h using Hep-GSH than when LL and TX were used (35 ± 5 vs 50± 5 and 56± 5, p<0.05). Embryo division at 48 h obtained better results with the ICSI + F/T and LL treatment, while the highest blastocyst percentage at D8 was obtained using TX. Conclusions. Blastocysts can be produced through ICSI, using spermatozoa from fresh or cryopreserved testicular tissue. The spermatozoa treated with TX and LL produced a higher percentage of BL than the spermatozoa treated with Hep-GSH. Further experiments should be carried out using spermatozoa obtained from different sources, in order to improve embryo development after the ICSI

Aptitud reproductiva de toros criollo lechero tropical

Criollo Lechero Tropical (CLT) cattle have desirablecharacteristics for tropical cattle production.However, the reproductiveperformance of CLT bulls at different ages and in different seasons of theyear has not been evaluated under tropical climate conditions. In this study,eight bulls were assigned to two age groups: 1) G1 (n = 5): bulls at age19.3±0.4 months and 260±9 kg of live weight, and 2) G2 (n = 3): bullsat age 30.5±3.1 months and 371±29 kg of live weight. Throughoutone year, libido was evaluated in a 0 to 10-point scale and blood serumtestosterone concentrations were determined. In the different seasons ofthe year, libido scored from 8 to 10 in both groups of bulls. Bulls from G2had higher concentrations of testosterone (P < 0.05), and in both groupstestosterone concentrations were higher during the morning hours (P <0.05). In conclusion, CLT bulls from both groups showed a high reproductivepotential throughout the seasons of the year.El ganado Criollo Lechero Tropical (CLT) posee características deseables para la ganadería tropical. Sin embargo, se desconoce el comportamieto reproductivo de toros CLT de diferentes edades durante las diferentes estaciones del año en clima cálido. En este estudio, ocho toros se asignaron según su edad a los siguientes grupos: 1) G1 (n=5): machos de 19.3 ± 0.4 meses y 260 ± 9 kg de peso y 2) G2 (n=3): toros de 30.5 ± 3.1 meses y 371 ± 29 kg de peso. Durante un año se evaluó la libido en una escala de 0 a 10 puntos y se midieron las concentraciones séricas de testosterona. En las diferentes estaciones del año la libido presentó un puntaje de 8 a 10 para ambos grupos. Los toros del G2 tuvieron mayor concentración de testosterona (P&lt;0.05) y en ambos grupos ésta fue mayor en la mañana (P&lt;0.05). En conclusión, los toros CLT de ambos grupos mostraron un amplio potencial reproductivo durante las diferentes estaciones del año

Andrological characteristics of tropical milking criollo Bulls

Objective: To assess the testicular and semen characteristics of Tropical Milking Criollo (CLT) bulls in the subhumid Mexican tropics. Design/methodology/approach: Eight bulls were evaluated and distributed in two groups: G1 (n5): young bulls and G2 (n3): adult bulls. All bulls were managed under grazing and evaluated throughout a year. From each bull, the following measurements were taken once a month: live weight, body condition score, scrotal circumference, and testicular width, length and volume. Semen was obtained every 3 months via an artificial vagina. The evaluated semen variables were: aspect, volume, mass and individual motility, and sperm concentration and morphology. Results: Live weight and testicular measurements linearly increased during the study in bulls from both groups. All bulls had a scrotal circumference larger than the minimum threshold value for cattle and high-quality semen. Study limitations/implications: The low availability of CLT bulls prevented the inclusion of a larger number of animals in the research. This low animal availability makes it necessary to establish standard values for testicular measurements and semen characteristics in the CLT breed in order to select the best individuals as sires and contribute to its conservation. Findings/conclusions: The CLT bulls had good scrotal circumference and semen quality from a young age and into adulthood. These traits make CLT bulls an important alternative for livestock breeding in the tropics

Livestock resources and their conservation facing climate change

Objective: To analyze the importance of local livestock resources facing climate change. Methodology: A review of studies referenced in scientific databases disclosed in the livestock sector and animal genetic resources was made within the context of climate change. Results: Livestock breeding is an economic activity that contributes to the food security of the country; in view of its importance, technologies and necessary changes to perform this according to the accelerated changes that occur in the environment, brought by human activity, should be implemented. Implications: Using highly productive races that depend on external inputs and are not adapted to face the effects of climate change, make it a priority to appraise the use of local races that contribute to production under adverse conditions that prevail in warm weathers in the inter-tropical zone. Conclusions: Adapted local race breeders should preserve local animal genetic resources so that they perform as a climate change adaptation alternative that will have repercussions on livestock production systems

Livestock resources and their conservation facing climate change

Objective: To analyze the importance of local livestock resources facing climate change. Methodology: A review of studies referenced in scientific databases disclosed in the livestock sector and animal genetic resources was made within the context of climate change. Results: Livestock breeding is an economic activity that contributes to the food security of the country; in view of its importance, technologies and necessary changes to perform this according to the accelerated changes that occur in the environment, brought by human activity, should be implemented. Implications: Using highly productive races that depend on external inputs and are not adapted to face the effects of climate change, make it a priority to appraise the use of local races that contribute to production under adverse conditions that prevail in warm weathers in the inter-tropical zone. Conclusions: Adapted local race breeders should preserve local animal genetic resources so that they perform as a climate change adaptation alternative that will have repercussions on livestock production systems

Comparación de dos métodos de transferencia de embriones en el ganado criollo lechero tropical

It is unknown which is the best method for the cryopreservation of Tropical Milking Criollo cattle (TMC) embryos for transfer. The objective of this study was to compare slow curve and vitrification methods in pure and Criollo TMC; this was done in the states of Veracruz (CP) and Guerrero (OG). The treatments were randomly assigned: in CP, six embryos in TMC and four in half-caste by slow curve, as well as five in TMC and five in half-caste by vitrification. In OG, four were destined for slow curve in TMC and five in half-caste; for vitrification, six in TMC and five in half-caste. The data analysis was done using the Fisher's test. No effect was found in the cryopreservation method in the gestation percentage (p>0.05); 10 and 20 % were obtained in CP (p≤0.50), and 11 and 27% in OG (p≤0.375) for slow curve and vitrification, respectively.En el ganado Criollo Lechero Tropical (CLT), se desconoce el mejor método para la criopreservación de sus embriones para transferencia. El objetivo del estudio fue comparar los métodos por curva lenta y vitrificación en receptoras CLT puras y mestizas; se realizó en Veracruz (CP) y Guerrero (OG). Los tratamientos se asignaron de forma aleatoria: seis embriones para CLT y cuatro para mestizas por curva lenta, así como cinco en CLT y cinco en mestizas por vitrificación para CP. En OG, se destinaron cuatro para curva lenta en CLT y cinco en mestizas; para vitrificación, seis en CLT y cinco en mestizas. El análisis de datos se realizó con la prueba de Fisher. No se encontró efecto del método de criopreservación en el porcentaje de gestación (p>0.05) y se obtuvieron 10 y 20 % en CP (p≤0.50), 11 y 27 % en OG (p≤0.375) para curva lenta y vitrificación, respectivamente

Estimativa dos efeitos diretos, maternos e de heterose para permanência produtiva em dialelo com Holandês e Pardo Suíço em condições subtropicais

O objetivo do estudo foi estimar os efeitos genéticos diretos, maternos e de heterose para características de longevidade em dialelo com Holandês e Pardo Suíço, sob condições subtropicais. Foram utilizadas informações produtivas e genealógicas de 171 vacas Holandesas, Pardas Suíças e seus cruzamentos F1 recíprocos; totalizando 568 lactações. As características de longevidade avaliadas foram: a probabilidade de as fêmeas terem uma, duas, três, quatro e cinco lactações dado que tiveram o primeiro parto. Devido à natureza dicotômica das variáveis ​​respostas, elas foram analisadas com um modelo linear generalizado, assumindo uma distribuição binomial com função de ligação probit. Cada modelo incluiu os efeitos fixos da raça do pai, raça da mãe, ano de nascimento, hora de nascimento e interação raça do pai por raça da mãe. A heterose individual para cruzamentos específicos, bem como os efeitos diretos e maternos, foram estimados segundo o modelo descrito por Dickerson (1973). Os efeitos diretos e maternos não foram significativos (p&gt;0.05) para as características analisadas. A heterose foi significativa (p&lt;0.05) para permanência produtiva da terceira à quinta lactação, com valores de 0.26 ± 0.10, 0.18 ± 0.07 e 0.19 ± 0.07 pontos percentuais, respectivamente. Os cruzamentos recíprocos tiveram maior probabilidade de sobreviver a lactações sucessivas do que os animais de raça pura, sugerindo que os agricultores podem usar um sistema de cruzamentos e os efeitos da heterose para maximizar a permanência das vacas no rebanho