Carlos Vásquez-Peláez

Effect of dietary protein:energy ratio on intake, growth and metabolism of juvenile green abalone Haliotis fulgens

Abstract Juvenile green abalone Haliotis rufescens were grown under laboratory conditions at 21±1 °C and fed formulated diets consisting of different protein:energy ratios (mg protein/kcal), 62, 74, 85, 100, 108, for 60 days. The level of crude protein ranged from approximately 26% to 44% while the energy content remained constant at about 4.1 kcal g −1 . Growth ranged from 3.63 to 12.33 mg day −1 . The growth of abalone fed the 100 and 108 diets was significantly greater than that of each of the other diets. Protein efficiency ratio increased as the dietary protein content increased except for the T108 diet (44% crude protein). Abalone apparently consume food to satisfy an energy requirement. Caloric expenditure due to metabolism was estimated for abalone fed diets with protein ratios of 62, 85, 100. Energy loss due to respiration did not vary appreciably among abalone fed the different diets. The proportional distribution of dietary energy into fecal, digestible, growth, and metabolic energy was estimated for abalone fed these diets. Apparent dry matter digestibility was among the lowest for abalone fed the 100 P:E diet, but growth of abalone fed this diet was significantly higher than that of each of the other treatments except the 108 diet. Unexplained energy loss to achieve balance ranged from 7% to 28.5%, some of which is probably due to differential mucus and ammonia production. Results suggest a potential for the reduction of both dietary protein and lipid without causing any adverse effects on the growth response.

Effect of triacylglycerols in formulated diets on growth and fatty acid composition in tissue of green abalone (Haliotis fulgens)

Abstract Isocaloric formulated diets containing four different sources of triacylglycerols (olive, corn, linseed and cod liver oils) at three levels (1.5%, 3.0% and 5.0%, total added dietary lipid=5.0%) and a crude protein content of 37.5% to 39.9% were fed to juvenile green abalone ( Haliotis fulgens ). Growth and fatty acid composition of the muscle tissue were compared to that of abalone fed a reference diet that contained no added lipids (0.25% total lipids). After 75 days of culture in a flow-through system, no significant differences in growth were found among abalone fed the different oil types. Responses to different dietary levels of lipid were significantly different but not to sources of oils. Maximum growth was achieved at a 1.5% inclusion of oil sources. It appears that abalone have a great capacity to synthesize lipid from carbohydrate sources. Results also suggest that abalone are capable of desaturation and elongation of 18 C polyunsaturated fatty acids (PUFAs) of the n −3 and n −6 family to 20:5 n −3 and 20:4 n −6. Synthesis of 22:6 n −3 from 20:5 n −3 is not reflected in the results. The lack of a growth response to the different levels of highly unsaturated fatty acids (HUFA) provided by the different oils included in the experimental diets may be due to an insufficient duration of the experiment to achieve an essential fatty acid deficiency. The relationship between fatty acid profiles of tissue and the diets fed to the abalone suggests that metabolic activity of the gut microflora is not a source of essential fatty acids.

GROWTH AND ENERGY UTILIZATION OF JUVENILE PINK ABALONE HALIOTIS CORRUGATA FED DIETS CONTAINING DIFFERENT LEVELS OF PROTEIN AND TWO STARCH:LIPID RATIOS

Abstract Juvenile pink abalone Haliotis corrugata (initial mean length = 10.7 ± 0.3 mm; initial mean weight = 0.15 g) were grown under laboratory conditions in an aerated flow-through seawater system at 21 ± 1°C. For 131 days, abalone were fed diets containing three different levels of protein (42%, 36% and 32%), each level containing two ranges of starch:lipid ratios (1.5–1.8 or 3.2–3.6). The gross energy content of the diets ranged from 4.26–3.68 kcal/g. Within a particular protein level, growth did not differ significantly. When dietary protein levels exceeded 32%, a trend of higher growth of abalone was observed for dietary treatments that contained lower levels of lipid (higher starch to lipid ratios). The amount of protein consumed daily for the 32% dietary protein is apparently insufficient to meet requirements for energy and maximum growth. No notable diet-dependent differences in the proportional composition (dry weight) of the shell and the soft tissue, and the energy content of the soft tissue were observed. Daily food intake and consumed energy were significantly different among treatments, being inversely related to the calculated P:E ratios. The increased consumption may have been somewhat overestimated because of loss arising from lower water stability of the diets. Ammonia excretion ranged from 7.9–4.8 μg NH4+ /h /g abalone but was not significantly different among treatments except for the treatment containing 32% crude protein and a low carbohydrate:lipid ratio. Specific Dynamic Action (SDA) comprised nearly 50% of measured oxygen consumption and did not significantly differ among treatments. Respiration increased during the night showing a typical circadian pattern reported in Haliotis genera. Measured mucus production did not vary among treatments. Carbohydrate preferentially serves as the principal energy source and a consistent amount of dietary protein is also used as an energy source, regardless of dietary protein content. Within a developed energy budget, approximately 70% of the ingested energy was lost through feces, and approximately 25% of the ingested energy was metabolized, with 7% to 10% channeled to growth. A direct determination of available digestible energy was not possible because of the inability to collect sufficient feces to estimate fecal energy. The results suggest that practical diets should include levels of dietary protein that are approximately 35% protein to meet requirements for energy and maximum growth. In addition, carbohydrates seem to be the preferred energy source and lipid levels should be minimized to the extent that essential fatty acids requirements are met.

Estimación de heredabilidad de la curva de crecimiento en el borrego de raza Chiapas en México

Summary Genealogical and live body weight monthly records from 790 sheep of the Chiapas breed born between 1991 and 2004 were used to characterize the growth curve and estimate (co)variance components for the parameters (A, k and b) of the Gompertz function. The pedigree structure consisted of 790 sheep, including 45 rams and 379 ewes. Estimation of (co)variance components for each growth parameter was achieved using a univariate animal model with the restricted maximum likelihood (REML) method. Estimated values of heritability were: A (adult weight) 0.21 ± 0.06; b (integration constant) 0.25 ± 0.07; k (maturity rate) 0.16 ± 0.06; age at the inflexion estimated as (ln(b)/k) 0.24 ± 0.07; and absolute growth rate as [k*(0.368*A)* ln(A/0.368*A)] 0.22 ± 0.07. The growth of males was 24% (P < 0.05) faster than that of females; adult weight was 25 ± 0.7 kg for males and 23 ± 0.7 kg for females; absolute growth was 59 ± 2 g and 44 ± 2 g per day for males and females respectively. The Chiapas breed of sheep is a small animal with a slow growth curve, probably due to its adaptation to the environmental conditions where it lives. Growth curve can be modified through selection.