Seaweeds possess a wide range of bioactive compounds that can be beneficial in sustainable intensification systems. This study explored the effect of green seaweed (Ulva spp.) meal (SWM) on apparent nutrient digestibility and physiological responses of Boschveld indigenous chickens. Two-hundred and seventy-five hens (202.4 ± 6.65 g live-weight; 4-weeks-old) were reared on five isoenergetic and isoproteic diets formulated by adding SWM at 0 (SW0), 20 (SW20), 25 (SW25), 30 (SW30), and 35 g/kg (SW35). Neutral detergent fibre digestibility quadratically responded (R2 = 0.244; p = 0.042) to SWM levels. No significant dietary influences were observed on apparent nutrient digestibility values. Repeated measures analysis showed significant diet × week interaction effect on weekly feed intake and growth performance. Dietary inclusion of SWM increased (p < 0.05) feed intake and overall body weight gain but not feed conversion efficiency. No significant linear and quadratic trends were observed for blood parameters except for basophils (R2 = 0.172; p = 0.047), which linearly declined with SWM levels. Dietary SWM inclusion only influenced (p < 0.05) mean corpuscular volume, mean corpuscular concentration, and mean corpuscular haemoglobin concentration. We concluded that seaweeds have the potential to be used as a feed ingredient for indigenous chickens.

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Using black soldier fly larvae meal (BSFM) in place of fishmeal is an ingenious strategy for sustainable fish aquaculture. However, BSFM has not been evaluated for dusky kob (Argyrosomus japonicus), an economically important fish in South Africa. Therefore, this five-week study investigated the effect of partially replacing fishmeal with BSFM on feed utilization, growth performance, and blood parameters of juvenile dusky kob in a recirculating aquaculture system. Four diets were formulated by replacing fishmeal in a commercial dusky kob diet with BSFM at the rate of 0 (BSFM0), 50 (BSFM50), 100 (BSFM100), and 200 g/kg (BSFM200). Fish length and weights were measured weekly, while blood analyses were performed at the end of Week 5. For fish length and weight gain, there were neither linear nor quadratic responses in Weeks 1–4, while quadratic trends (y = 14.77 (± 0.19)−0.11 (± 0.05)x + 0.01 (± 0.00) x2; R2 = 0.35 and y = 49.85 (± 1.53)−1.22 (± 0.39)x + 0.06 (± 0.02) x2; R2 = 0.47, respectively) were observed in Week 5 in response to BSFM levels. Quadratic effects (y = 1.75 (± 0.15) + 0.10 (± 0.04)x − 0.01 (± 0.00) x2; R2 = 0.39) were also observed for feed conversion ratio (FCR) in response to BSFM inclusion levels. Fish fed BSFM200 had a similar overall FCR and specific growth rate as those reared on BSFM0. All blood parameters fell within the normal range for the dusky kob. We concluded that 20% dietary replacement of fishmeal with BSFM does not compromise feed utilization and growth performance of juvenile dusky kob.

There is some evidence that single‐cell proteins such as yeast have the potential to improve feed utilization in aquaculture fish, but this has not been investigated in the economically important dusky kob, Argyrosomus japonicus. This study was, therefore, designed to determine the effect of graded levels of dietary inactivated brewer's yeast, Saccharomyces cerevisiae, on the growth performance and hemobiochemical parameters of dusky kob in a 6‐week feeding period. Five isonitrogenous and isoenergetic diets—consisting of three brewer's yeast‐containing diets at rates of 50,150, and 300 g/kg dry matter (BY5P0, BY15P0, and BY30P0, respectively); a commercial dusky kob diet containing 10% probiotic mix but no brewer's yeast (BY0P1, positive control); and a commercial dusky kob diet with neither the probiotic mix nor the yeast (BY0P0, negative control)—were formulated. A total of 65 fish, weighing an average of 7.02 ± 0.10 g, were randomly distributed to each of 20 replicate tanks. Each dietary treatment was randomly allocated to four tanks and offered to fish at a rate of 2.8% fish body weight per day. A total of 10 fish from each tank were randomly sampled once a week for length and weight measurements. Blood was drawn from five fish per tank (20 fish per treatment) for hematology and serum biochemical analyses at the end of the 6 weeks. Fish on the BY0P0 diet achieved the highest weight gain of 18.53 ± 0.69 g after 6 weeks. Growth rate was significantly reduced in the groups fed BY15P0 and BY30P0 diets compared to the BY0P0, BY0P1, and BY5P0 groups. Fish fed the BY0P0 diet recorded the highest average feed conversion efficiency (FCE) of 0.22, while the BY30P0‐fed group recorded the lowest FCE of 0.15. Hematocrit and alanine transaminase levels declined with increasing levels of yeast. It can be concluded that the maximum inclusion level of brewer's yeast that does not impair growth performance and health of dusky kob is 50 g/kg.

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Despite aquaculture being hailed as the fastest growing farming sector in the world, South African aquaculture is still lagging behind. This article aims to highlight challenges (mostly beyond their control) that South Africa’s emerging aquaculture entrepreneurs have to endure in order to find a breakthrough into the industry. Availability of necessary resources such as land, water, infrastructure,financial support and access to markets, as well as crime are among challenges faced by these entrepreneurs on a daily basis. Limited human resources in capacity building, skills and aquaculture expertise also hinders the development and expansion of aquaculture in South Africa. Complex legislation governing aquaculture further limits the development of this sector to prospective investors. Fish and machinery theft in fish farms has an adverse effect, which had resulted in many enterprises closing down in recent years. South Africa is not a traditional fish-eating nation and this phenomenon has seen many emerging entrepreneurs struggling to locally commercialize their produce. It is well known that fish consumption provides human nutrition with essential nutrients necessary for normal body function. Thus,aquaculture has the potential to contribute to food and nutrition security and alleviate poverty in rural communities. However, plenty of initiatives need to be developed by government and the private sector to develop a sustainable aquaculture industry. These initiatives should involve the establishment of an aquaculture friendly legislation that would support emerging aquaculture entrepreneurs. Several financial institutions view aquaculture as a high-risk business,and as a consequence,decline financial support or loan requests from emerging farmers.Focused research as a strategic initiative to develop aquaculture species that would be first priority for local markets is encouraged. This article explores the challenges facing emerging entrepreneurs and suggests possible solutions that might assist in the development of the aquaculture sector in South Africa. We postulate that constructive and regular engagements between the government and private sector is a key to a sustainable and prosperous aquaculture sector in South Africa.

The main objective of this investigation was to test the effect of a standard commercial feed (Skretting Active ZA) on the growth performance of juvenile dusky kob (Argyrosomus japonicus), compared to the same feed when supplemented with six commercially available additives over a period of 10 weeks. A common additive in trial treatments contained two yeast strains (84% Candida utilis and 16% Saccharomyces cerevisiae) that were incorporated at 33% of the total feed mass. The yeast combined diet was also tested per se as a base experimental diet (BED). In the remaining five trials the BED was respectively mixed with selected herbal extracts or pharmaceutical probiotics to comparatively measure possible superimposed growth enhancement. Herbal extracts were Aquapro® (herbal powder), Liv-Up® (herbal granule), Liv-Up® (liquid) and UNBP-20® (liquid). The pharmaceutical 2-strain probiotic was Probiflora® (Lactobacillus acidophilus and Bifidobacterium bifidus). Experimental diets closely reflected comparative approximate nutrient values with respect to protein (46-48%), carbohydrate (17-18%), fat (14%) and fibre (11-12%) content. Juvenile dusky kob (n=50 per tank) of about 5.77±1.28 g were experimentally grown for 10 weeks in tanks (465 L) of a suitable recirculating aquaculture system (RAS) (24-25°C) with natural lighting. Supplement added diets induced a substantial average body growth of 43.3 g, except for slower (P<0.05) growth measured for the Live-Up®-liquid additive trial. The SGR was of the same magnitude between the BED and its complex with the mentioned additives. Also, the BED (46.5% protein) mediated a faster SGR (P<0.05) than the control diet without yeast (50% protein). The best FCR (0.95) was achieved with the BED added herbal product UN-BP20®. The dietary inclusion of the inactivated yeast types is recommended for dusky kob commercial diets since it showed enhanced growth performance and possible production viability.