Food intake rate and delivery strategy in aquaculture

In aquaculture,it is important to estimate in advance how much food cultured animals would take.The rate of food consumption by cultured animals to available food amount is defined as the food intake rate(FIR) in this paper.To some extents,FIR reflects the quality of food,the health of cultured animals and the delivery efficiency.In practice,it is difficult to estimate in advance the accurate quantity of food that cultured animal needs.Usually,food is provided more than the need by animals,causing excess food that may pollute water and environment.Our experiments in past years show that FIR at 80% is recommended.

Definition of spatial positions within foraging Greater White-fronted Geese flocks from an individual's perspective:Cost-benefit dynamics change with the distance to flock edge

The costs and benefits of group living are not evenly distributed among individuals that occupy different spatial positions within a group(central or peripheral).However,the definitions of central and peripheral positions may artificially mask the true dynamics of cost and benefit of individuals.Using wintering foraging Greater Whitefronted Geese(Anser albifrons)flocks as our study system,we measured individual spatial position within a flock as distance to the flock edge.First,we tested the effects of distance to edge on the antipredation cost and foraging benefit of individual goose using generalized linear mixed models(GLMMs).Flock size and number of neighbors and their interactions with distance to edge were included as fixed effects in GLMMs.Then we used piecewise regression to determine the threshold value of distance to edge to classify central and peripheral individuals.Our results indicated distance to edge significantly affected percent of time spent on vigilance(vigilance time),percent of time spent on foraging(foraging time)and intake rate(pecks/min),whereas other factors had no effects.We found that the critical distance that predicted changes in behavior was around 2.5 m.Birds 2.5 m or less from the edge of the group were more vigilant,and had less efficient foraging than more central individuals.Behavioral differences between central and peripheral individuals were more easily detected when the birds were classified by the method introduced in this study than by the traditional minimum convex polygon method.Our research provides researchers a dichotomous classification scheme that places individuals into peripheral and central positions from an individual's perspective.

Influence of Different Sources and Levels of Fat on Palatability of Tibetan Mastiff

In order to compare the palatability of Tibetan mastiff to different fat sources and fat levels, four kinds of raw lipid materials （ soybean oil, sunflower seed oil, chicken fat and butter） were selected to prepare five candidate diets with different fat source combinations and three different fat level combinations （6%, 10% and 14% ）. Ten healthy Tibetan mastiff adults were randomly divided into two groups. The intematianally useful double-pot cultivation design was employed to record the daily feed intake and preferred diet of each Tibetan mastiff, and further to calculate the intake rate. The butter group assumed higher feed intake and intake rate than the chicken fat group （P 〈0.01）, and the preferred diet as well （83%）. The feed intake and intake rate of chicken fat group was significantly higher than chicken fat and butter （ 1：1 ） combined group （ P 〈 0.01 ）. No significant difference was observed in the diet palatability of butter diet to Tibetan mastiff to different plant oil sources （ P 〉 0.05）. For various fat level combinations, the diet with highest fat content diet H23 assumed higher feed intake and intake rate than low fat diet H22 and H21 （P 〈0.05）. It is concluded that the palatability of butter diet to Tibetan mastiff is higher than chicken fat and its combined diet （ butter：chicken fat = 1：1 ） ; with fat level of 6% - 15%, high fat diet provides Tibetan mastiff a better palatability in comparison with low fat diet.

Preliminary Study on Feeding Habits of Anthocidaris crassispina

Abstract Employing experimental-ecological methods, the feeding and vitality of adult Anthocidaris crassispina were investigated. The results showed that A. cras- sispina exhibited an obvious preference on five different seaweeds, with the preference order of Betaphycus gelatinum 〉 Sargassum hemiphyllum 〉 Gelidium amansii 〉 Ulva lactuca 〉 Codium fragile. The daily feed intake of A. crassispina differed among U. lactuca, S. hemiphyllum and B. gelatinum. The feeding was affected by water temperature, seaweed species and body weight. The optimal vitality and feed intake were observed under 23 -27℃, which were inhibited under whether too higher or too lower temperature. Under the optimal temperature for feeding, the daily feed intake of adult A. crassispina assumed an exponentially-decreasing trend with increase of body weight.

A Study on the Effects of the Intake Port Configurations on the Swirl Flow Generated in a Small D.I. Diesel Engine

This paper investigates the effect of intake port configuration on the swirl that is generated within a direct injection(D.I.) diesel engine. The in-cylinder flow characteristics are known to have significant effects on fuel-air mixing, combustion, and emissions. To clarify how to intensify the swirl flow, a swirl control valve(SCV) and a bypass were selected as design parameters for enhancing the swirl flow. The optimal intake port shape was also chosen as a parameter needed to efficiently generate a high swirl ratio. The results revealed that a key factor in generating a high swirl ratio was to control the intake airflow direction passing through the intake valve seat. Further, the swirl intensity was influenced by changing the distance between the helical and tangential ports, and the swirl flow was changed by the presence of a bypass near the intake valve seat. Additionally, the effect of intake port geometry on the in-cylinder flow field was investigated by using a laser sheet visualization method. The experimental results showed a correlation of swirl ratio and mass flow rate. In addition, we found that employing the bypass was an effective method to increase swirl ratio without sacrificing mass flow rate.