Differences In Food Conversion Efficiency Research Articles

Effect of culture methods on individual variation in the growth of sea cucumber Apostichopus japonicus within a cohort and family

There is substantial individual variation in the growth rates of sea cucumber Apostichopus japonicus individuals. This necessitates additional work to grade the seed stock and lengthens the production period. We evaluated the influence of three culture methods (free-mixed, isolated-mixed, isolated-alone) on individual variation in growth and assessed the relationship between feeding, energy conversion efficiency, and individual growth variation in individually cultured sea cucumbers. Of the different culture methods, animals grew best when reared in the isolated-mixed treatment (i.e., size classes were held separately), though there was no difference in individual variation in growth between rearing treatment groups. The individual variation in growth was primarily attributed to genetic factors. The difference in food conversion efficiency caused by genetic differences among individuals was thought to be the origin of the variance. The level of individual growth variation may be altered by interactions among individuals and environmental heterogeneity. Our results suggest that, in addition to traditional seed grading, design of a new kind of substrate that changes the spatial distribution of sea cucumbers would effectively enhance growth and reduce individual variation in growth of sea cucumbers in culture.

Effects of starvation and recovery on growth, proximate composition and RNA/DNA ratio in juvenile spotted ivory shell (<I>Babylonia areolata</I>)

To investigate the compensatory growth responses of the scavenging gastropod Babylonia areolata,a refeeding after starvation study was performed at (25.8±1.7) ℃. Juvenile spotted ivory shells weighing a mean of 5.25 g were starved for 7 (S7),15 (S15),25 (S25),and 40 (S40) days,respectively,and then fed to satiation once a day during the 30 days refed period. The four corresponding control groups were fed to satiation during the experiment. Three tanks each containing 30 snails made up a group. The results indicated that the water contents of the whole soft body increased gradually during starvation,and was significantly higher than that of the control when the snails were fasted for 15 days (P0.05). The lipid and glycogen contents were significantly lower than those of the controls when food were prohibited for 15 days and 25 days respectively (P0.05),while there were no significant differences in protein contents (P 0.05 ). The ratios of RNA/DNA in foot muscle and hepatopancreas of the snails both decreased gradually during the fasting period. After 30 days recovery growth,except for the water content in the S40 group,which was significantly higher than that of the control (P0.05),there were no significant differences in other biochemical composition between refed and control groups(P0.05). The ratios of RNA/DNA were near or markedly higher than that of the control except in hepatopancreas of the S40 group which was lower than that of the control (P 0.05 ). The feeding rate (FR) during refed period was higher (for S7,S15) or significantly higher (for S25,S40) than that of the controls which were fed throughout the experiment,there were no significant differences in food conversion efficiency (FCE) and increments of body weight between the S7,S15,S25 groups and their controls respectively,as well as no significant differences were found between the S7,S25 groups and the controls respectively as to specific growth rate (SGR) (P 0.05 ),while the SGR was markedly higher than that of the control in the S15 group (P 0.05 ). Whereas there were significant decreases in the FCE,SGR and increment of body weight for the S40 group,although the FR of this group was greatly increased compared to the control (P0.05). In conclusion,the snails could utilize lipid and glycogen first as energy resource when being deprived of food,and there is complete compensatory growth in snails as the starvation period was no more than 25 days. The results of the present study indicate that prolonging the feeding intervals properly can facilitate the culture manipulation and spare food under the premise of not affecting the growth rate of the snails,and the RNA/DNA ratios in the two tissues are a valid indicator of nutritional condition in spotted babylon juveniles.

Comparative studies on the growth and survival of African catfish, <i>Clarias gariepinus</i> (Burchell, 1822) juveniles reared in cages suspended in concrete tank and earthen pond in Umudike, Abia State

Comparative studies were carried out to evaluate the growth and survival of African catfish, Clarias gariepinus reared in cages suspended in tank and pond of surface area 24m 2 and 450m 2 respectively. The result showed that growth was better in pond than in tank. At the end of the culture period, the percentage survival was 97.96 % in tank and 93.88 % in pond and this did not differ significantly (p>0.05) among the stocking densities. There was no significant difference in food conversion efficiency (FCE) and protein efficiency ratio (PER) at different stocking densities between the two systems. Fish stocked at 7m -3 grew better than those stocked at higher densities (14m -3 and 28m -3 ). Statistical analysis of the data collected showed significant difference (P< 0.05) in the specific growth rate. The analysis of the labour cost required for the adoption of net cage culture in both concrete tank and earthen pond systems, proved it to be more efficient and profitable for juvenile catfish production.

The effect of food competition and relative size of group members on growth of juvenile gilthead sea bream, Sparus aurata [Pagrus aurata

The effects of food competition and relative size of group members on growth of sea bream, Sparus aurata were tested in groups composed of four fish. Each group consisted of a medium sized test fish (approximately 250 mg) and three fish larger or smaller than the test fish. In the first experiment food competition was addressed directly by contrasting its presence with its absence. Neither food competition nor relative size of school members had a significant effect on growth. However, there was a highly significant interaction between these two main effects. Under conditions of food competition the medium sized test fish had a three times higher specific growth rate when surrounded by small vs large fish. Under conditions of no food competition when the test fish were separated during feeding a similar but reverse pattern occurred due to differences in food conversion efficiency. In the second experiment, the effects of food quantity and relative size of group members were tested. Both main effects and their interaction were highly significant. Under conditions of low food competition (i.e., surplus food supply) fish grew again better when surrounded by larger fish as compared to their growth rate when surrounded by smaller ones. Size matching via a differential growth rate in a schooling species such as sea bream was suggested to increase the confusion effect by reducing the ability of a predator to focus on an odd sized fish. The implications of direct competition for food for the efficient culture of this species are discussed.

Differences among breed crosses of cattle in the conversion of food energy to calf weight during the preweaning interval

The objective of this study was to determine whether F1 cows that differ in genetic potential for weight at maturity and milk yield vary in the conversion of food energy to calf weight gain. Food intakes and weight change data were recorded by pen for cows and calves from approximately 45 d postpartum. Cows assigned to the study were 7- to 9-yr-old F1s produced by top-crossing Angus, Hereford, Brown Swiss, Chianina, Gelbvieh; Maine Anjou, and Red Poll sires to either Angus or Hereford dams. Calves were sired by Simmentals. Experimental units were pens (10 to 12 cow/calf pairs); pen was replicated within breed of sire in each of 2 yr (n = 24). Calf weight gain and energy consumed by the dams differed among the F1s, as did the ratio of calf weight gain to energy consumed by the calf and cow. Angus or Hereford (35.8), Red Poll (35.7), or Maine Anjou (35.6) F1s produced more calf weight per unit of energy consumed (g/Mcal) by the cow and calf than Chianina (33.1) or Gelbvieh (33.7) F1 females; Brown Swiss cows were intermediate (34.3). Differences in food conversion efficiency exist among breed crosses. These differences seem to be associated with breed cross differences in genetic potential for milk yield and mature weight; an exception to this trend was the Maine Anjou.

Growth and Feeding Responses of Male versus Female Yellow Perch (Perca flavescens) Treated with Estradiol-17β

In yellow perch (Perca flavescens) (initially 13–16 g total weight) fed to satiation (3.0–3.5% of body weight per day), estradiol-17β (E2) at 15 μg/g diet stimulated weight gain and food consumption of both sexes but did not influence food conversion efficiency (FCE), as measured by weight gain of fish per weight of food consumed. Females fed to satiation gained more weight, consumed more food, and had higher FCE than males. In perch fed a restricted ration (1.2% of body weight per day), the differences between the sexes in weight gain were reduced and due entirely to differences in FCE, and weight gain was not improved by E2. Spatial segregation or integration of the sexes had no influence on sex-related growth patterns in perch fed either the satiation or restricted ration. Carcass composition of perch treated for 84 d with E2 at 2, 20, or 50 μg/g diet did not differ from that of controls. These data indicate that (1) estrogens promote growth in yellow perch by stimulating food consumption, (2) female perch outgrow males because of both greater food consumption and higher FCE, and (3) growth differences between the sexes are not a consequence of intersexual competition for food.

Effects of grouping and isolation on feeding, food conversion and energy expenditure of domestic chicks

At ambient temperatures of 25–30°C, domestic chicks gained more weight between 6 and 10 days of age when kept in groups of three than in isolation. This difference in growth rate, which was not affected by variation in social environment before testing, was due to a difference in food conversion efficiency only, and not to one in food intake. The only evidence of social enhancement of feeding was a temporary increase in feeding activity (but not food intake) shown by grouped chicks previously kept in isolation. The consistent difference in food conversion between grouped and isolated chicks was not due to differences in activity levels, digestibility, emotionality or stress, but was associated with a difference in metabolic heat production, or heat loss. Although there was little evidence of huddling by grouped chicks, their heat production was lower than that of isolates at ambient temperatures of 20 and 25°C, but not at 30 and 35°C; and the difference in food conversion efficiency disappeared at 35°C. It is concluded that isolates lack the opportunities that grouped chicks have for behavioral thermoregulation, but that all chicks achieve equal status energetically when the ambient temperature lies within or near the zone of minimal metabolic rate.

Some further observations upon the effects of varying the plane of feeding for pigs between weaning and bacon weight

Some further observations upon the effects of varying the plane of feeding for pigs between weaning and bacon weight

The early weaning of pigs IV. Comparisons of levels of antibiotic and sources of protein in diets for pigs weaned at 9 lb. live weight

In Exp. 1 groups of piglets weaned at about 9 lb. live weight were fed one of three 29% protein diets up to 26 lb. live weight. These diets A, B and C contained 42, 20 and 0% dried skim milk, 15, 25 and 32% white fish meal and 22, 34 and 47% rolled oat groats, respectively. At 26 lb. all pigs were changed over to a standard 17% protein diet.The replacement of about one-half of the dried skim milk in diet A with white fish meal and rolled oat groats caused 4% faster growth from 9 to 26 lb. live weight, but the replacement of all the dried skim milk caused growth over the same weight range to be slower by 6%. The quadratic component of these treatment effects was significant at P &lt; 0·0·25. The slower growth with the diet containing no dried skim milk was associated with a lower daily consumption of feed, and the improved growth rate with the intermediate skim milk level was probably associated with an improvement in food conversion efficiency. Treatment differences in food conversion efficiency before 26 lb. live weight, however, were not statistically significant. There were no significant carry-over effects of treatments upon performance from 26 to 50 lb. live weight.In Exp. 2 piglets weaned at about 9 lb. live weight were fed individually up to 40 lb. live weight. From 9 to 26 lb. antibiotic levels of 22, 45, 67 and 90 mg./lb. feed were compared, but from 26 to 40 lb. all pigs were fed a standard diet containing 18 mg. antibiotic/lb. In diets fed before 26 lb. the antibiotic was a mixture of 3 parts by weight chlortetracycline: 1 part by weight procaine penicillin. From 26 to 40 lb. live weight the antibiotic fed was chlortetracycline.Before 26 lb. live weight increases in antibiotic level caused average increases of up to 5% in growth rate and 4% in food conversion efficiency. Taken in conjunction with previous results the improvement in growth rate in favour of the highest antibiotic level was significant at P &lt; 0·05.There were no carry-over effects of antibiotic level on growth rate from 26 to 40 lb., but there was the suggestion of a linear trend whereby each increase in antibiotic level fed before 26 lb. caused a decrease in food conversion efficiency between 26 and 401b. (P = 0·10).The results are discussed in relation to financial economies which may be made in diets for early weaned pigs.

The response of different types of pigs to varying levels of feeding from weaning to bacon weight, with particular reference to carcass quality

The response of different types of pigs to varying levels of feeding from weaning to bacon weight, with particular reference to carcass quality