Fertility prediction in dairy goats from Murciano-Granadina breed: The role of sperm evaluation and female traits.

Fertility is one of the most economically important traits in farm animals, due to the direct and indirect costs associated to low pregnancy rates. Thus, one of the priority goals in animal reproduction is to predict the performance that the semen doses will have in vivo based on the quality values obtained in laboratory assays. Attempts have been made for getting a predictive model of fertility of frozen-thawed sperm in dairy goats, but similar studies have not been conducted for chilled goat buck sperm doses that are mostly used for artificial insemination in many countries including Spain. We study how parameters of in vitro sperm quality and characteristics of Murciano-Granadina dairy goats may affect the in vivo fertility obtained after artificial insemination with semen doses chilled at 4 °C. Moreover, this information was used for obtaining predictive models of the fertility. Sixty-three ejaculates from 13 males were used to prepare chilled doses for the insemination of 495 goats over 13 sessions. Fresh and chilled sperm were evaluated for motility and plasma membrane integrity with a computer-assisted sperm analysis system and flow cytometry, respectively. Fertility was determined at parturition, according to the kidding goats. Overall fertility was 59.6%. Pearson's correlation coefficients between in vivo fertility and quality variables of fresh sperm were not significant and were low (below 0.34 in absolute value) for chilled sperm. Females' characteristics had a low negative impact on fertility (correlation coefficients of -0.19 with age, -0.20 with parturitions and -0.11 with total milk yield obtained in the best lactation). Fixed and mixed logistic regression procedures were used trying to explain the fertility results. None of the models accurately predicted fertility, but the best models included the percentage of total motile sperm or average path velocity from fresh semen, age of the females and the session effect (uncontrolled environmental effects). These analyses showed that primiparous goats were 2.42 times more likely to get pregnant than goats that had kidded four or more times. Our field assay data on fertility in Murciano-Granadina dairy goats highlighted the importance of making quality controls of sperm, of choosing the doses presenting high percentages of motile sperm exhibiting regular trajectories and of selecting the youngest goats for AI, after their first kidding. Efforts should continue to obtain better predictive models for improving fertility in goat dairy herds.

Brain correlates of the intrinsic subjective cost of effort in sedentary volunteers.

One key aspect of motivation is the ability of agents to overcome excessive weighting of intrinsic subjective costs. This contribution aims to analyze the subjective cost of effort and assess its neural correlates in sedentary volunteers. We recruited a sample of 57 subjects who underwent a decision-making task using a prospective, moderate, and sustained physical effort as devaluating factor. Effort discounting followed a hyperbolic function, and individual discounting constants correlated with an indicator of sedentary lifestyle (global physical activity questionnaire; R=-0.302, P=0.033). A subsample of 24 sedentary volunteers received a functional magnetic resonance imaging scan while performing a similar effort-discounting task. BOLD signal of a cluster located in the dorsomedial prefrontal cortex correlated with the subjective value of the pair of options under consideration (Z>2.3, P<0.05; cluster corrected for multiple comparisons for the whole brain). Furthermore, effort-related discounting of reward correlated with the signal of a cluster in the ventrolateral prefrontal cortex (Z>2.3, P<0.05; small volume cluster corrected for a region of interest including the ventral prefrontal cortex and striatum). This study offers empirical data about the intrinsic subjective cost of effort and its neural correlates in sedentary individuals.

The nigrostriatal pathway: axonal collateralization and compartmental specificity.

This paper reviews two of the major features of the nigrostriatal pathway, its axonal collateralization, and compartmental specificity, as revealed by single-axon labeling experiments in rodents and immunocytological analysis of human postmortem tissue. The dorsal and ventral tiers of the substantia nigra pars compacta harbor various types of neurons the axons of which branch not only within the striatum but also in other major components of the basal ganglia. Furthermore, some nigrostriatal axons send collaterals both to thalamus and to brainstem pedunculopontine tegmental nucleus. In humans, the compartmental specificity of the nigrostriatal pathway is revealed by the fact that the matrix compartment is densely innervated by dopaminergic fibers, whereas the striosomes display different densities of dopaminergic terminals depending on their location within the striatum. The nigral neurons most severely affected in Parkinson's disease are the ventral tier cells that project to the matrix and form deep clusters in the substantia nigra pars reticulata.

Chemical architecture of the posterior striatum in the human brain.

The neurochemical organization of the posterior caudate nucleus (CN) (body, gyrus and tail) and putamen (Put) was analyzed in the human brain using adjacent sections stained for acetylcholinesterase (AChE), limbic system-associated membrane protein (LAMP), enkephalin (ENK), parvalbumin (PV), calbindin (CB) and tyrosine hydroxylase (TH). Striosomes were visualized in all striatal regions but the anterior two thirds of the CN tail. They were highly immunoreactive (-ir) for ENK and LAMP, devoid of PV and AChE staining, and surrounded by a ring of tissue with pale TH- and CB-ir neuropil. In the Put, other rings of tissue completely free of ENK labeling surrounded certain striosomes (clear septa). In the CN body, gyrus and tail some markers revealed gradients and heterogeneities along the dorsoventral and mediolateral axes. A rim of striatal tissue densely stained for ENK and LAMP and poorly labeled for PV was noticeable along the lateral edge of the Put and the dorsolateral sector of the CN body. Our results illustrate a chemical architecture in the posterior striatum that is heterogeneous and slightly different from that found in the more anterior striatum.

Factors affecting pregnancy rate in artificial insemination with frozen semen during non-breeding season in Murciano-Granadina goats: a field assay.

An artificial insemination programme was carried out to study the effect of factors such as depth of semen deposition, inseminator skill, farm, sire and expression of oestrus on pregnancy rate in Murciano-Granadina (MG) goats during non-breeding season and using frozen semen. Frozen-thawed semen from six males was applied by three technicians to inseminate a total of 551 goats in 17 farms distributed throughout the Mediterranean area of Spain. Pregnancy rate was determined at 6 weeks after insemination by transabdominal ecography. Overall pregnancy rate was 57%. Farm and depth of semen deposition affected pregnancy rate, whereas the sire and the technician had no effect. The deeper the semen was deposited in the genital tract, the higher was the rate of pregnancy obtained, being greater when the catheter reached the uterus. In spite of the relevant difference observed (48.2% vs 59.0%), pregnancy rate of females not coming into oestrus until 30 h after sponge removal was not significantly different, compared with those showing oestrus during the OD procedure. In conclusion, our field assay data on AI in MG goat with frozen-thawed semen showed that post-cervical insemination presented significantly greater pregnancy rate in comparison to when semen is deposited in the vagina or in the caudal part of the cervix.