FAKTOR-FAKTOR YANG MEMPENGARUHI NILAI TAMBAH USAHA TERNAK SAPI DI DESA TUMARATAS KECAMATAN LANGOWAN BARAT

ABSTRACT FACTORS INFLUENCING VALUE ADDED OF CATTLE BUSINESS AT TUMARATAS VILLAGE DISTRICT OF LANGOWAN BARAT.The objective of this research was to know value added and factors influencing value added on cattle business at Tumaratas Village district of Langowan Barat, Minahasa Regency. Primary data were collected from 100 samples of households by using questionnaire. Respondents were purposively selected by considering farmers at least has one cattle and ever sold it out. . Data were analyzed by using descriptive and quantitative analysis by using multiple regression model. Study results indicated that the more cattle owned by household the more value added of cattle achieved. The average of value added per animal unit was IDR 4,434,543/years. Partially factors of inseminator cost, cost of natural mating and household labor on cattle business had positive affect on value added of cattle while household labor on food crops business had negative impact on value added of cattle.Key words: Value added, inseminator cost, natural mating cost, household labor

The influence of virginity and induced sterility on Drosophila melanogaster females and males life span

Reproduction and life span are negatively interrelated in both sexes, however sex differences in costs of reproduction are poorly understood. It was shown that mating cost has a main contribution to costs of reproduction in both sexes. molecular signals from gonads exceed cost of gametes production.

The quantitative genetics of sexual selection in the dung fly Sepsis cynipsea

In the common dung or black scavenger fly Sepsis cynipsea (Diptera: Sepsidae) several morphological and behavioural male and female traits interact during mating. Previous studies show that males attempt to mount females without courtship, females use vigorous shaking behaviour in response to male mounting, the duration of shaking is an indicator of both direct and indirect female choice and sexual conflict, and larger males enjoy a mating advantage. We conducted a quantitative genetic paternal half sib study to investigate the genetic underpinnings of these traits, notably body size (the preferred trait) and the associated female preference, and to assess the relative importance of various models generally proposed to account for the evolution of sexually selected traits. Several morphological traits and female shaking duration were heritable, thus meeting a key requirement of all sexual selection models. In contrast, two traits indicative of male persistence in mating were not. Male longevity was also heritable and negatively correlated with his mating effort, suggesting a mating cost. However, the crucial genetic correlation between male body size and female shaking duration, predicted to be negative by both 'good genes' and Fisherian models and positive by the sexual conflict (or chase-away) model, was zero. This could be because of low power, or because of constraints imposed by the genetic correlation structure. Based on our rsults we conclude that discriminating sexual selection models by sole means of quantitative genetics is difficult, if not impossible.