Estimation of genetic parameters and relationships between type traits and milk yield of Holstein cows in Turkey / [Estimativa de parâmetros genéticos e relações entre características de tipo e produção de leite das vacas Holstein na Turquia]

In this study, milk yield, reproductive yield, and type traits of 533 Holstein cows in the first lactation raised in 54 farms were examined. In the three-year study, phenotypic (rP) and genetic (rG) correlations between type traits and milk yield were estimated based on the variance elements and heritability of the type traits of Holstein cows in the first lactation. Linear identification and scoring systems have been applied to classify the cows according to type traits. Heritability and correlations were estimated with ASREML models. The type traits included stature, angularity, rump width, hocks, rear udder height, central ligament, teat length, body capacity, feet and legs, udder composite and final score for genetic correlations with 305-day milk yield were estimated as -0.49, -0.14, -0.93, 0.35, 0.40, 0.11, -0.65, 0.70, 0.31, 0.54, and 0.70, for phenotypic correlations were estimated as 0.28, 0.28, 0.30, 0.21, 0.35, 0.39, -0.06, 0.46, 0.48, 0.56, and 0.58 respectively. Among the phenotypic correlations between the type traits, especially the phenotypic correlations between the final score and various type traits were found to be high and significant. The fact that these traits are in high correlation with other traits and milk yield may enable these to be used as indirect selection criteria in the selection for milk yield.(AU)

Neste estudo, foram examinadas a produção de leite, a produção reprodutiva e as características de tipo de 533 vacas Holstein na primeira lactação criadas em 54 fazendas. No estudo trienal, as correlações fenotípicas (rP) e genéticas (rG) entre características de tipo e produção de leite foram estimadas com base nos elementos de variação e hereditariedade das características de tipo das vacas Holstein na primeira lactação. Sistemas de identificação linear e de pontuação foram aplicados para classificar as vacas de acordo com os traços de tipo. A hereditariedade e correlações foram estimadas com os modelos ASREML. Os traços de tipo incluíam estatura, angularidade, largura da alcatra, jarretes, altura do úbere traseiro, ligamento central, comprimento das tetas, capacidade corporal, pés e patas, composição do úbere e pontuação final para correlações genéticas com a produção de leite de 305 dias foram estimados como -0. 49, -0,14, -0,93, 0,35, 0,40, 0,11, -0,65, 0,70, 0,31, 0,54, e 0,70, para correlações fenotípicas foram estimadas como 0,28, 0,28, 0,30, 0,21, 0,35, 0,39, -0,06, 0,46, 0,48, 0,56, e 0,58 respectivamente. Dentre as correlações fenotípicas entre os traços de tipo, especialmente as correlações fenotípicas entre a pontuação final e vários traços de tipo foram encontradas como altas e significativas. O fato destes traços estarem em alta correlação com outros traços e a produção de leite pode permitir que sejam usados como critérios de seleção indiretos na seleção para a produção de leite.(AU)

The dynamics of coordinated group hunting and collective information transfer among schooling prey.

Predator-prey interactions are vital to the stability of many ecosystems. Yet, few studies have considered how they are mediated due to substantial challenges in quantifying behavior over appropriate temporal and spatial scales. Here, we employ high-resolution sonar imaging to track the motion and interactions among predatory fish and their schooling prey in a natural environment. In particular, we address the relationship between predator attack behavior and the capacity for prey to respond both directly and through collective propagation of changes in velocity by group members. To do so, we investigated a large number of attacks and estimated per capita risk during attack and its relation to the size, shape, and internal structure of prey groups. Predators were found to frequently form coordinated hunting groups, with up to five individuals attacking in line formation. Attacks were associated with increased fragmentation and irregularities in the spatial structure of prey groups, features that inhibit collective information transfer among prey. Prey group fragmentation, likely facilitated by predator line formation, increased (estimated) per capita risk of prey, provided prey schools were maintained below a threshold size of approximately 2 m(2). Our results highlight the importance of collective behavior to the strategies employed by both predators and prey under conditions of considerable informational constraints.

Effect of supine exercise on platelet aggregation and fibrinolytic activity.

In 12 healthy young men, strenuous cycling exercise in the supine position, caused platelet aggregability to decrease and the ADP threshold to rise from 7.0 microM resting, to 9.5 exercising (P < 0.01). At the same time, fibrinolytic activity increased markedly: euglobulin clot lysis time shortened from 178 to 68 min, PAI-1 fell from 8.91 to 5.16 IU ml-1, and t-PA rose from 0.56 to 3.95 IU ml-1, all three values were significant to P < 0.01. When the erect posture was assumed after lying at ease for 1 h after exercise, it did not increase platelet activity as expected, but caused a modest increase of fibrinolytic activity. These results suggest that supine exercise will not affect the haemostatic system adversely.