Genotype x dose of artificial insemination interaction for buck fertility

Ponencia publicada en ITEA, vol.104El objetivo de este trabajo fue estimar los parámetros genéticos de la fertilidad tras la IA con 3 tipos de dosis obtenidas de eyaculados de machos de la línea Caldes: 1) tipo 10: con 10 x 106 espermatozoides/ml y 24h de conservación en un diluyente comercial tipo A. 2) tipo 40: con 40 x 106 espermatozoides/ml y las mismas condiciones de conservación que las del tipo 10. 3) tipo X: dosis preparadas tras diluir los eyaculados con un diluyente comercial tipo B (1:5) siendo desconocida la concentración y sin periodo de conservación. Se realizaron 3,628 IA con dosis del tipo 10 sobre hembras cruzadas, 3,027 con dosis del tipo 40 y la misma población de hembras, y 5,779 con dosis del tipo X sobre hembras puras de la línea Caldes. La fertilidad tras la IA con dosis del tipo 10 (F10), 40 (F40) y X (FX) fue considerada un carácter distinto en cada caso, de tipo binario. Los datos se analizaron utilizando un modelo umbral tri-carácter. La estima de la media de la distribución marginal posterior (DMP) de F10 menos F40 fue de -0.13. Este resultado indica un claro efecto de la concentración sobre la fertilidad, que podría no ser lineal. Las medias de la DMP de F10 menos FX y F40 menos FX fueron -0.37 y -0.23, respectivamente, lo que indica que el efecto de las condiciones de conservación sobre la fertilidad podría ser más importante que el de la concentración ya que FX fue muy próxima a la fertilidad tras la MN y la concentración del tipo de dosis X sería en promedio de unos 50 x 106 espermatozoides/ml. Las heredabilidades parecen ser similares para F10 y F40 y ambas mayores que las correspondientes a la fertilidad tras la MN y a FX. La interacción del genotipo x concentración de la dosis de IA es prácticamente despreciable debido a que las varianzas genéticas fueron similares para F10 y F40 y a que su correlación genética fue próxima a 1. Sin embargo, la interacción podría ser de mayor importancia entre el genotipo y las condiciones de conservación.The aim of this research was to estimate genetic parameters of male fertility after AI with three different types of AI doses obtained from ejaculates of bucks belonging to the Caldes line: 1) type 10: doses with 10 x 106 spermatozoa/ml and a period of 24 h of storage at 18ºC in a saline extender A. 2) type 40: doses with 40 x 106 spermatozoa/ml and the same storage conditions as type 10. 3) type X, doses prepared with semen diluted (1:5) with a saline extender B, but with unknown sperm dosage and no storage period. 3,628 AI were performed with the type 10 doses using crossbred females, 3,027 with the type 40 doses and the same population of females, and 5,779 with the type X doses, using purebred M. Piles et al. ITEA (2008), Vol. 104 (2), 160-168 16 females from the Caldes line in a different farm. Fertility after AI with type 10 doses (F10), type 40 doses (F40) and type X doses (FX) was considered as three different binary traits. Data were analyzed under a three-trait threshold model. The mean of the marginal posterior distribution (MPD) for F10 minus F40 was estimated to be -0.13. This result indicates a clear effect of the sperm dosage on fertility, which could be non-linear. The mean of the MPD of F10 minus FX and F40 minus FX were respectively, -0.37 and -0.23 which indicates that the effect of the storage conditions on fertility could be even more important on fertility than sperm dosage, since FX was very close to fertility after NM and sperm dosage of this type of doses was in average lower than 50 x 106 spermatozoa/ml. Heritabilities seem to be similar for F10 and F40 and both of them could be higher than heritability of male fertility after NM and FX. Variance of the genotype x sperm dosage interaction was almost negligible since additive variances were similar for F10 and F40 and their genetic correlation was close to 1. However, this interaction could be more important between the genotype and the storage conditions

Clinical use of human chorionic gonadotropin in dairy cows: an update.

Human chorionic gonadotropin (hCG) has a potent luteinizing hormone (LH)-like effect in cattle that extends the life span of thecorpus luteum (CL) and increases progesterone synthesis, induces ovulation throughout the estrous cycle, promotes the formation ofaccessory corpora lutea when applied in the early luteal phase, and modifies follicular wave dynamics increasing the frequency of three-wave dominant follicular cycles. As hCG acts on ovarian cells independently of the pituitary gland and its effect is longerlasting than that produced by endogenous LH release, use of hCG rather than gonadotropin-releasing hormone (GnRH) could betargeted at populations of subfertile cows. This review describes the clinical use of hCG to improve the reproductive performance of dairy cows. In addition, we describe recent developments in the therapeutic use of hCG and studies addressing the benefits ofincluding hCG in estrus and ovulation synchronization protocols. Our review ends with a critical discussion of how earlier findingsrelated to ovarian responses to hCG treatment can be interpreted in the light of recent advances in the clinical applications of hCG

Causes of declining fertility in dairy cows during the warm season

In the Northern Hemisphere, from June to September and in the Southern Hemisphere from December to March, there are periods of reduced fertility (sub-fertility) in dairy cows that are described as summer infertility. Several factors contribute to sub-fertility during this time, such as ambient temperature, humidity and photoperiod. During the warm season there is a reduction in feed intake that may compromise the energy balance of the cow and/or induce an imbalance in the activity of the hypothalamo-hypophyseal-ovarian axis. These factors reduce the reproductive performance of the cow and compromise the quality of oocytes, embryos and corpora lutea. This paper reviews current knowledge on the metabolic and endocrine mechanisms that induce summer infertility and describe their effects on follicle, oocyte and embryo development in dairy cows

Relationships between peripheral maternal immune status during the peripartum period and postpartum reproductive disorders

Pregnancy and peripartum period are characterised by transient changes in the maternal immune system, noticeable at the peripheral level. The aim of the study was to determinate the effect of placental retention and metritis on peripheral white blood cells in 91 pregnant dairy cows from day 200 of pregnancy to 30 postpartum. Blood samples were automatically analysed with HemaVet® Multispecies Haematology system and total and differential leukocyte counts were recorded. Data was statistically analysed using GLM repeated measures ANOVA to test the effect of reproductive disorders on peripheral white blood cells. Cows with placental retention had significantly lower leukocyte, neutrophil and lymphocyte counts (P<0.05), and cows with metritis had lower neutrophil and eosinophil counts (P<0.01) than cows not suffering reproductive disorders during the peripartum period. Day of pregnancy and parturition also affected peripheral lymphocyte and monocyte counts (P<0.01). Maternal immune dysfunction during the peripartum period may predispose to reproductive disorders postpartu

Plasma progesterone concentration is not reduced in pregnant non-aborting heifers experimentally infected with neospora caninum

El feto mamífero es antigénicamente un cuerpo extraño para la madre y para sobrevivir se producen una serie de interacciones de inmunosupresión entre la madre y el mismo. La hormona clave que provoca inmunotolerancia fetal por parte de la madre es la progesterona (Hansen et al. 1986), produciendo un cambio hacia la respuesta inmune tipo Th2 y evitando así el aborto que produciría una excesiva respuesta Th1 (Roberston, 2000). El efecto regulador de la progesterona es ejercido directa o indirectamente a través de mediadores secundarios como las serpinas uterinas, conocidas como SERPINA14, que se encuentran presentes en el endometrio, fluidos fetales y el ovario (Padua y Hansen, 2010). Neospora caninum es un protozoo intracelular obligado considerado la causa más importante de aborto en vacuno lechero a nivel mundial. En las granjas lecheras la ruta de infección más frecuente es la transplacentaria, donde las madres infectadas naturalmente transmiten el parasito a los fetos durante la gestación (Almería y López-Gatius, 2013). La mayoría de terneros nacen clínicamente normales, aunque aproximadamente un 95% están infectados por N. caninum. El aborto o la infección congénita ocurren cuando el parásito atraviesa la barrera placentaria e infecta al feto, provocando el aborto principalmente hacia los 5-7 meses de gestación (Almería y López-Gatius, 2013). Las razones por las cuales algunas vacas infectadas abortan y otras no, siguen siendo desconocidas. Es bien conocido que la infección por N. caninum modifica los patrones hormonales durante la gestación en vacuno lechero. Por ejemplo, la seropositividad frente a este parásito ha sido asociada con incremento de prolactina y progesterona plasmática (Garcia-Ispierto et al. 2010, 2013) y reducción de glicoprotefnas asociadas a gestación (PAGs) (Garcia-Ispierto et al., 2015). También, se ha observado una correlación negativa entre la expresión génica de SERP/NA 14 en la placenta y la respuesta adaptativa humoral y celular en la placenta y linfonodos uterinos de vacas infectadas experimentalmente con N. caninum (Serrano-Pérez et al., 2016, 2017). El presente estudio se realizó durante el segundo trimestre de gestación en terneras gestantes experimentalmente infectadas con N. caninum el dla 11 O de gestación. Se seleccionó este momento de infección debido a que es cuando la mayoría de abortos tienen lugar en animales infectados en condiciones de campo. Debido al tropismo del parásito por el folículo ovárico (Silva et al., 2012) y al aumento de progesterona detectado en animales seropositivos a N. caninum, el objetivo de este estudio fue determinar si las novillas infectadas experimentalmente mostraban cambios en Ja concentración plasmática de progesterona tras la infección. Un segundo objetivo fue correlacionar la expresión génica de SERPINA 14 en el cuerpo lúteo con la concentración plasmática de progesterona.Neospora caninum is a majar cause of abortion in cattle worldwide. However,immune-endocrine interactions during pregnancy in Neospora-infected cows remainunknown. This study examines plasma progesterone concentration in dairy heifers experimentally infected with N. caninum that did not abort, and also assessed possible interrelations between expression patterns of SERPINA 14 in corpus luteum tissues and plasma progesterone concentrations. The study population was constituted of tour noninfected controls and three heifers experimentally infected wíth N. caninum on Day 11 O of pregnancy with live foetuses at euthanasia. Both groups were euthanized on Day 152 of gestation. At euthanasia, blood samples were collected to determine progesterone concentrations. Samples of corpus luteum tissues (CL) were collected to determine gene expression of SERPINA14. No relationships were detected between infection and plasma progesterone concentration (12.5 ± 1.5 ng/ml in controls vs. 12.8 ± 3.7 ng/ml in infected dams). There was not significan! correlation between plasma progesterone concentration and SERPINA14 expression in CL (r: 0.607, P=0.148). In conclusion, N. caninum had no impacts on luteal funclion, at least in terms of repercussions on plasma progesterone concentrations.Este estudio fue financiado por MINECO (AGL2012-39830-C02-01/02) y fondos FEDER. R. Mur-Novales disfruta de una beca FPI (BES-2013-063215).Publishe

Prepartum blood lead concentrations linked to subsequent cyclicity in high-producing dairy cows in a non-industrial area

This study sought to identify the possible presence of lead (Pb) in blood and if detected to examine the relationship between blood Pb concentrations during the transition period and subsequent reproductive performance in high-producing dairy cows reared in a non-industrial area. Forty seven multiparous dairy cows were examined and/or sampled on Days 251-257 of gestation (visit 1,V1), the day of calving (V2) and on Days 8-14 (V3), 15-21 (V4), 22-28 (V5), 29-35 (V6), 36-42 (V7) and 50-56 (V8) postpartum. A mean level of 130±17 ppm (± SD) of Pb was detected in feed samples. Blood samples were collected for Pb determination from V1 to V5 and lead was present in all collected blood samples. One unit increase in blood Pb concentration in the V1 sample led to a 0.3-fold reduction (P=0.02) in the likelihood of a cow being cyclic. Mean blood Pb concentrations were 0.97±0.11 and 2.6±0.1 μg/L for cyclic (n=24) and non-cyclic (n=23) cows, respectively. Cows with a body condition score (BCS) loss of ≥0.75 units between V1 and V4 (n=24) showed higher Pb concentrations throughout the study period than the remaining cows (n=23; P <0.001). In conclusion, blood Pb levels were detected in all cows. Prepartum blood Pb concentrations were negatively related to subsequent cyclicity. Cows with higher Pb levels experienced a greater BCS loss during the transition period. Routine blood Pb tests could indicate a higher risk of anoestrus in cows with higher Pb concentrations