Formulated Pellet Research Articles

Effect of Feed Texture and Dimensions, on Feed Waste Type and Feeding Efficiency in Juvenile Sagmariasus verreauxi

The “messy” feeding behaviour of spiny lobsters remains an obstacle for formulated feed development. This study examined the relationship between feeding efficiency and feed waste by juvenile spiny lobster, Sagmariasus verreauxi, fed different formulated pellet diameters or lengths across two separate experiments. Feed texture (hard and dry pellet, HDP; soft and moist pellet, SMP) was also examined. Juvenile lobsters were fed experimental feeds at 0.5% BW daily over a 6 h duration. The resulting feed waste was categorised as either feeding-related waste (FRW) or non-feeding-related waste (NFRW). For all feed types, the FRW increased with increasing pellet diameter and pellet length. The increase in FRW corresponded with a decrease in NFRW, particularly for HDP, resulting in no difference in total feed waste in any treatment investigated. Thus, even with improved feeding efficiency with small feed dimensions, feed intake was not improved. Feed leaching rate decreased with increasing pellet size, suggesting a more rapid decline in feed attractiveness for smaller pellets. This finding indicates that currently a counteractive interaction exists between pellet size and feed attractiveness and suggests improving attractiveness would further enhance feeding. Future research should aim at optimising feed dimensions simultaneously to support efficient feeding whilst enhancing attraction/gustatory stimulations.

Effect of Different Levels of Dietary Lipids on Reproductive Performance of Captive Broodstock of <i>Macrobrachium rosenbergii</i>

The present paper reports the results of a laboratory experiment to study the effect of different levels of dietary lipids on reproductive performance of captive broodstock of giant freshwater prawn Macrobrachium rosenbergii. Three formulated pellet diets were prepared containing 2% (D1), 4% (D2) and 6% (D3) lipid and fed to adult females of M. rosenbergii (Av. body weight - 28 g) at 5% of the biomass per day for 60 days. Prawns fed D3 showed significantly higher (P<0.05) weight gain (221.16±6.48 mg/day) compared to those fed D1 and D2. Similarly, significantly higher (P<0.05) reproductive parameters like fecundity (eggs/ g body weight) (1153.6±174.25), egg clutch weight (g) (4.9±0.25) and gonado-somatic index (6.82±0.27) were also found in prawns fed D3. Reproductive effort (g eggs/ female x100), post–hatch fecundity (nos. of larvae/ g female) and mid gut gland somatic index (%) also showed a similar trend. The present results clearly indicated that dietary lipid level of 6% significantly enhances reproductive performance of captive stock of M. rosenbergii compared to 2% and 4% lipid levels.

Field Efficacy of a Feed-Based Inactivated Vaccine against Vibriosis in Cage-Cultured Asian Seabass, Lates calcarifer, in Malaysia.

Vibrio spp. are important aquaculture pathogens that cause vibriosis, affecting large numbers of marine fish species. This study determines the field efficacy of a feed-based inactivated vaccine against vibriosis in cage-cultured Asian seabass. A total of 4800 Asian seabass, kept in a field environment, were separated equally into two groups (vaccinated and non-vaccinated) in duplicate. Fish of Group 1 were orally administered the feed-based vaccine on weeks 0 (prime vaccination), 2 (booster), and 6 (second booster) at 4% body weight, while the non-vaccinated fish of Group 2 were fed with a commercial formulated pellet without the vaccine. Fish gut, mucus, and serum were collected, the length and weight of the fish were noted, while the mortality was recorded at 2-week intervals for a period of 16 weeks. The non-specific lysozyme activities were significantly (p < 0.05) higher in the fish of Group 1 than the non-vaccinated fish of Group 2. Similarly, the specific IgM antibody levels in serum and mucus were significantly (p < 0.05) higher in Group 1 than in Group 2, as seen in the second week, with the highest level 8 weeks after primary immunization. At week 16, the growth performance was significantly (p < 0.05) better in Group 1 and showed lower bacterial isolation in the gut than Group 2. Despite the statistical insignificance (p > 0.05), the survival rate was slightly higher in Group 1 (71.3%) than Group 2 (67.7%). This study revealed that feed-based vaccination improves growth performance, stimulates innate and adaptive immune responses, and increases protection of cultured Asian seabass, L. calcarifer, against vibriosis.

The Libido, Scrotal Circumference, Sperm Quality, and Testosterone Levels of Matured Boer Bucks Supplemented with Selenium

A study was conducted to determine the effect of three levels of selenium (Se) supplementation on the libido, scrotal circumference, sperm quality, and testosterone levels in matured Boer bucks. The feeding trial was conducted at MARDI Bachok Station, Bachok, Kelantan, Malaysia, for over six months. A total of 18 matured Boer bucks aged two years with an initial body weight of 53.28±0.62 kg, and no experience of sexual activity was selected for the feeding trial. All animals were randomly divided into three dietary treatments based on a completely randomized design (CRD). Group A and B were supplemented with organic Se at doses of 0.18 mg/kg DM and 0.36 mg/kg DM, respectively, whereas group C acted as a control group (without Se supplementation). Their basal diet consisted of 60% formulated pellet and 40% Brachiaria dictyoneura grass. Daily feed offered (DM basis) was based on 3% of mean body weight. Libido, scrotal circumference, and sperm quality were measured every two months during the feeding trial. Testosterone levels were determined at the end of the feeding trial. The results indicated that the basal diet (control group) was deficient in Se, with the concentration of 0.004 mg/kg. Supplementation of 0.18 mg Se/kg DM only improved the libido and sperm quality (p<0.05). Supplementation of 0.36 mg Se/kg DM significantly (p<0.05) increased libido, sperm quality, and testosterone levels. It is summarized that supplementation of 0.36 mg Se/kg DM has the potential to improve the reproductive performance of bucks, although it occurred at the adult stage.

Formulating fungal spores to prevent infection by trichostrongylids in a zoological park: Practical approaches to a persisting problem

Two different formulations containing a blend of spores of the filamentous fungi Mucor circinelloides and Duddingtonia flagrans have been assayed against trichostrongylids in wapitis captive in a grassy parcel from a zoological park and dewormed with fenbendazole. One approach (sprayed-on pellets) consisted of providing them, during 10 months, nutritional pellets sprayed the spores just before to be ingested, and the other (formulated pellets) involved the administration of pellets industrially manufactured with the spores for an identical period. Data collected on wapitis treated with fenbendazole without receiving spores during a 10-months interval were considered as controls. The effect of these strategies was evaluated through the analysis of feces collected directly from the soil, by estimating the reduction of the counts of eggs of trichostrongylids per gram of feces (EPG). The possibility of side effects in the digestive tract, respiratory apparatus or on the skin was assessed. The coprological analyses showed that, despite the successfulness of fenbendazole, the values of trichostrongylids egg-output increased four months later above 300 EPG. Through the administration of pellets sprayed spores, a significant EPG reduction of 69% (30–100) was recorded, and 71% (36–100) by giving the wapitis pellets industrially enriched with the spores. No unfavorable effects were observed among the wapitis taking the spores. It is concluded that ingestion of a blend of spores of M. circinelloides and D. flagrans every two days affords a beneficial long-term effect on controlling the infection by trichostrongylids in wild captive animals.

The contribution of naturally occurring food items to the diet of Cherax destructor when fed formulated diets of differing protein levels

To improve growth rates of Cherax spp. raised for human consumption, considerable research has been conducted to establish nutritional requirements for the formulation of a food pellet. The problem with much of this research is that feed requirements between laboratory raised animals and those under pond culture conditions often differ. The difference is thought to be due to the consumption of naturally occurring food sources in addition to formulated pellets. Our study utilised stable isotope techniques to investigate the contribution of naturally occurring food items to the growth of Cherax destructor fed formulated diets differing in composition and raised in two different environments created in artificial ponds. Environment 1 contained no natural food items, whilst environment 2 recreated the naturally occurring food items contained within a commercial growout pond. Dietary treatments 1 and 2 were isoenergetic (12.50 MJ/kg) pellets designed specifically for crayfish, differing only in protein level (30% and 19% crude protein (CP) respectively), dietary treatment 3 was a commercially available pellet used to feed silver perch (40.5% CP, 13.5 MJ/kg) and dietary treatment 4 received no formulated pellets and had access only to naturally occurring food items. Despite the differences between diets and environments, there was no significant difference between weight, abdomen length and abdomen width in any of the fed treatments in either of the environments. Although unfed treatments were significantly smaller in all growth characteristics than fed treatments, those in the natural environment were larger than those in the clean environment. Orbital carapace length (OCL) did not differ between any of the diets or environments. Survival of animals was significantly higher in environment 1 than in environment 2. The cause for this difference was a result of the death of the majority of animals in a single tub. Analysis of C and N stable isotope signatures revealed that animals in environment 1 consumed naturally occurring food items. Of the natural food items available, zooplankton had the largest contribution to the growth of tissue. Microphytobenthos (MPB) also had a significant contribution to animals fed crayfish diet 1. However, despite the contribution of these items to growth, no growth advantage was conferred when pelleted feed was also provided. These results demonstrate that C. destructor consume naturally occurring food items even when provided with a formulated pellet and that suitable growth can be achieved with diets containing CP levels as low as 19%. We recommend testing of even lower protein levels in formulated diets as these may have no negative impact on growth, whilst further reducing the cost of feeds.

Evaluation of Stocking Density and Feeding Regime on Production of Red Swamp Crawfish in Outdoor Mesocosms

Seven stocking densities and three feeding regimes were evaluated, in combination, to determine their effects on production and relative condition of red swamp crawfish, Procambarus clarkii, in outdoor mesocosms. Juveniles were grown from November through June at densities of 5 to 35/m2 with either no cultivated rice, cultivated rice, or cultivated rice+formulated pellets as food resources. Crawfish size was influenced primarily by stocking density, survival was equally influenced by density and feeding regime, and yield was affected mostly by feeding regime. Individual harvest weight and survival decreased with an increase in stocking density. Most crawfish exceeded 20 g at 5 and 10/m2 in treatments with cultivated rice, but significant stunting occurred in all feeding regimes at 15/m2 or higher. Survival decreased with increased density, and was significantly less in the no-rice system, presumably from starvation and cannibalism. Mean crawfish yield in rice (1549 kg/ha) and rice+feed (1629 kg/ha) treatments was about 2.5 times higher than in the no-rice treatment (618 kg/ha). Formulated feed did not prevent stunting at high densities, but crawfish provided feed were in better physiological condition. Planted rice with an initial population density of about 10/m2 appears to provide the best combination to maximize both size and yield.

Weaning requirements of larval mulloway, Argyrosomus japonicus

Mulloway (Argyrosomus japonicus) is an emerging aquaculture species in Australia, but there is a need to improve the production technology and lower costs, including those associated with larval rearing and live feeds. Three experiments were conducted to determine appropriate weaning strategies from live feeds, rotifers (Brachionus plicatilis) and Artemia, to cheaper formulated pellet diets. Experiment 1 examined the effects of feeding Artemia at different levels [0%, 50% or 100% ration of Artemia fed from 18 days after hatching (dah); based on current hatchery protocols] and a pellet diet from two larval ages (14 or 23 dah). In addition, rotifers were supplied to larvae in all treatments for the duration of the experiment (14–29 dah), at which time all larvae were successfully weaned onto the pellet diet. No significant (P>0.05) differences existed between the growth of fish fed a 50% and 100% ration of Artemia; however, fish fed a 0% ration of Artemia had significantly (P<0.05) reduced growth. The time of pellet introduction had no significant (P>0.05) effects on the growth of larvae. Experiments 2 and 3 were designed to determine the size [total length (TL), mm] at which mulloway larvae selected Artemia equally or in preference to rotifers, and pellet (400 μm) equally or in preference to Artemia respectively. Each day, larvae were transferred from a holding tank to experimental vessels and provided with rotifers (2 mL−1), Artemia (2 mL−1) or a combination of rotifers (1 mL−1) and Artemia (1 mL−1) (Experiment 2), and Artemia (2 mL−1), a pellet diet or a combination of Artemia (1 mL−1) and a pellet diet that was broadcast every 15 min (Experiment 3). After 1 h, a sub-sample of larvae was randomly selected from each replicate vessel (n=5) and the gut contents were examined under a light microscope. Mulloway larvae began selecting Artemia equally to rotifers at 5.2 ± 0.5 mm TL and selected pellets equally to Artemia at 10.6 ± 1.8 mm TL. Our results have led to the establishment of weaning protocols for larval mulloway, which optimize larval growth while reducing feed cost by minimizing the amount of Artemia used during production.

Recovery of intravenously infused chromium EDTA and lithium sulphate in the urine of cattle and their use as markers to measure urine volume

A series of metabolism experiments investigated the recovery of continuous-, intravenously infused chromium complexed with ethylenediamine tetra-acetic acid (CrEDTA) and lithium sulphate in the urine of cattle with a view to using the markers to estimate urine and metabolite output in grazing cattle. The recovery of Cr in urine from these infusions was similar (90%) in metabolism trials when cattle consumed three very contrasting diets: high-grain formulated pellet, lucerne hay (Medicago sativa) or low-quality native grass hay (predominantly Heteropogon contortus). By contrast, Li recovery in urine averaged 46.3 ± 0.40% and 72.6 ± 0.43% for native pasture and lucerne hays, respectively, but was not constant across days. There was negligible transfer of Cr from CrEDTA in blood serum to the rumen or faeces, whereas appreciable quantities of infused Li were found in both. The ratio of urine volume estimated by spot samples and marker dilution of Cr, to urine volume measured gravimetrically, was 1.05. In grazing studies using rumen-fistulated (RF) steers grazing seven different tropical and temperate grass and legume pastures, the ratio of concentrations of purine derivatives (PD) to Cr in spot samples of urine was shown to vary diurnally in the range of 49% to 157% of the average 24 h value. This finding indicated the need for regular sampling of urine to achieve an accurate average value for the PD : Cr ratio in urine for use in estimating urinary PD excretion and hence microbial protein production in the rumen. It was concluded that continuous, intravenous infusion of CrEDTA resulted in a constant recovery of Cr in the urine of cattle across diets and, provided an intensive sampling regime was followed to account for diurnal variation, it would be suitable as a marker to estimate urine volume and urinary output of PD in grazing cattle.

Applicability of Stable Isotope Analyses for Ecological Studies of Abalone: Estimation of Fractionation Values and Natural Diets

Controlled feeding experiments with juvenile abalone Haliotis discus hannai were performed to evaluate the suitability of stable isotope analyses for diet inference. Juvenile abalone were divided into five size groups with distinct isotopic ranges caused by different dietary regimes before the experiments. Three different foods were provided for 42 days: a benthic diatom Cylindrotheca closterium (BD), a macroalga Laminaria japonica (MA), and a formulated pellet (FP). For the FP diet, the smallest juvenile group (8.3 mm in mean initial shell length (SL)) showed significant changes in carbon and nitrogen stable isotope ratios from the natural diet within approximately 1 wk. Using final tissue-diet isotopic differences in the two largest juvenile groups for the FP diet, the fractionation values were estimated as 1.6& and 2.2& for d 13 C and d 15 N, respectively. An exponential decay function of the change in d 13 C with time indicated that the shortest period to complete equilibrium fractionation was >120 days. Given the estimated fractionation values, the major diets of juvenile abalone (1.9-6.9 mm in SL) in the field were inferred to be benthic microalgae and several red macroalgae.

Assessment of Five Shelter Types in the Production of Redclaw Crayfish Cherax quadricarinatus (Decapoda: Parastacidae) Under Earthen Pond Conditions

AbstractAn experiment was designed to assess the relative performance of several shelter types on the production of redclaw crayfish Cherar quadricarinatus under earthen pond conditions. Juvenile crayfish with a mean stocking weight of 12.76 g were cultured in 24 net pens at 12.5 m2 within a 0.2 ha earthen pond, and were provided with one of five shelter types or no shelter over 162 d. The various shelter types assessed were: mesh bundles, pipe stacks, car tires, elevated cement/fiber‐board sheets, and cement/fiber‐board sheets laid flat on the substrate. Crayfish in each pen were fed a formulated pellet diet three times each week. Treatments were assessed on the basis of crayfish growth, survival, harvest biomass and berry rate among females at harvest. There was no significant effect (P &gt; 0.05) of shelter type on growth; however, there was a highly significant effect (P &lt; 0.001) on survival with mesh bundles (75.1%), tires (51.4%), and pipe stacks (43.25%) performing significantly better than the no shelter control (15%). The consequence of equal growth and differing survival among treatments produced significant differences in harvest biomass (P &lt; 0.01). There were also significant differences in berry rate for the different treatments (P= 0.002), and a significant negative correlation of berry rate on survival for those treatments where shelter was provided. This experiment showed that the shelter types provided during pond culture had a significant effect on harvested biomass, primarily through its effect on survival. The efficacy of the mesh bundle shelters may be attributable to the variability in the size of the spaces provided, and the ability of the mesh to separate many individuals relative to the overall volume of the shelter.

Post-weaning growth of cattle in northern New South Wales. 1. Grazing value of temperate perennial pasture grazed by cattle

This paper describes the botanical components, seasonal herbage mass, and nutritive value of pastures used for post-weaning growth of CRC cattle at Glen Innes before their progression to subsequent finishing and meat quality studies. The pastures under study comprised introduced temperate perennial species (tall fescue, Festuca arundinacea; phalaris, Phalaris aquatica; perennial ryegrass, Lolium perenne; cocksfoot,Dactylis glomerata; white clover, Trifolium repens; and red clover, Trifolium pratense) grazed by yearling cattle and managed according to local practice to maintain herbage mass between pre-determined limits. The study took place on 3 adjacent pasture systems (P1, pasture only; P2, pasture plus formulated pellets fed in later winter–early spring; P3, pasture plus forage crop grazed in later winter–early spring) over the 3 years 1994–96 that included a severe 20-month drought event followed by a drought-recovery phase. Results are discussed in the context of the pasture feed year which was shown to comprise 3 distinct phases: (i) spring primary growth phase, high availability of green herbage mass (2500–4500 kg DM/ha) of very high digestibility (0.80–0.85) and very high N status (about 30 g N/kg DM); (ii) summer–autumn secondary regrowth, high availability of green herbage mass (2500–4000 kg DM/ha) but with only moderate nutritive value (0.65–0.70 digestibility, 15–20 g N/kg DM); and (iii) winter dormancy, low availability of green herbage mass (750–1500 kg DM/ha) but with high nutritive value (0.75–0.80 digestibility, 20–30 g N/kg DM). It was concluded that the limitations of the feed year for yearling cattle in this environment include a feed gap in winter–early spring due to low herbage mass associated with winter cold and a feed gap in summer–autumn associated with moderate nutritive value of secondary regrowth pasture.