Nutritional composition of black soldier fly (Hermetia illucens) prepupae reared on different organic waste substrates.

BACKGROUND: Black soldier fly larvae are converters of organic waste into edible biomass, of which the composition may depend on the substrate. In this study, larvae were grown on four substrates: chicken feed, vegetable waste, biogas digestate, and restaurant waste. Samples of prepupae and substrates were freeze-dried and proximate, amino acid, fatty acid and mineral analyses were performed. RESULTS: Protein content of prepupae varied between 399 and 431 g kg-1 dry matter (DM) among treatments. Differences in amino acid profile of prepupae were small. On the other hand, the ether extract (EE) and ash contents differed substantially. Prepupae reared on digestate were low in EE and high in ash (218 and 197 g kg-1 DM, respectively) compared to those reared on vegetable waste (371 and 96 g kg-1 DM, respectively), chicken feed (336 and 100 g kg-1 DM, respectively) and restaurant waste (386 and 27 g kg-1 DM, respectively). Prepupal fatty acid profiles were characterised by high levels of C12:0 in all treatments. CONCLUSION: Since protein content and quality were high and comparable for prepupae reared on different substrates, black soldier fly could be an interesting protein source for animal feeds. However, differences in EE and ash content as a function of substrate should be considered. © 2016 Society of Chemical Industry.

Maturation of digestive function is retarded and plasma antioxidant capacity lowered in fully weaned low birth weight piglets.

The digestive function of low birth weight (LBW) pigs post-weaning has been poorly studied. Therefore, newborns from eleven hyperprolific sows were weighed, weaned at 27·2 d and fed a starter diet until sampling. Sampling was done between 18 and 28 d post-weaning. An LBW piglet (n 19) was defined as a piglet having a birth weight less than 1 kg and less than the lower quartile of litter birth weights. Normal birth weight (NBW) piglets (n 13) were having a birth weight close to the mean litter birth weight. For each piglet, eighty-eight variables were determined. Data were analysed with linear models with type of piglet and litter as predictors. A principal component analysis was performed to determine the most important discriminating variables. In the LBW pig, the development of the digestive tract post-weaning was delayed: lower small-intestinal weight:length ratio due to a thinner tela submucosa and tunica muscularis and a higher secretory capacity, both in the distal jejunum. These observations might be a consequence of lower circulating insulin-like growth factor-1 (IGF-1) concentrations (126 (se 10·0) v. 158 (se 12·0) ng/ml for LBW and NBW, respectively) and a lower density of IGF-1 receptors in the proximal small intestine. Additionally, the plasma antioxidant capacity was lower for the LBW pig. Taken together, in the LBW piglet, the normal gut maturation post-weaning was retarded and this did not seem to be related to the weaning transition as such.

Effects of dose and formulation of carvacrol and thymol on bacteria and some functional traits of the gut in piglets after weaning.

Two trials were conducted to study the effects of dose and formulation of carvacrol and thymol on bacterial counts, metabolites and functional traits of the gut in weaned piglets. In the first experiment (Exp. I), 25 piglets (28 d, 6.59 +/- 0.48 kg BW) were allocated to five dietary treatments: a control diet, or the same diet supplemented with either carvacrol or thymol at doses of 500 and 2000 mg kg(-1). In the second experiment (Exp. II), 35 piglets (28 d, 7.99 +/- 0.73 kg BW) were assigned to seven dietary treatments: the same control diet as in Exp. I, or this diet supplemented with thymol in one of three formulations (on celite, on alphacel or microencapsulated) at doses of 500 and 2000 mg kg(-1). At 11/12 days post-weaning piglets were euthanised, and digesta from stomach, proximal and distal small intestine were sampled for bacteriological and biochemical analysis. Small intestinal tissue was sampled for histomorphological determinations. In none of the experiments or sections of the gut was the number of bacteria lowered by the carvacrol or thymol supplementation. In Exp. I, the villus/crypt ratio at the distal small intestine for the experimental diets (1.30-1.32) was higher than for the control diet (1.24) (p < 0.05). Thymol fed animals in Exp. II had a lower number of intra-epithelial lymphocytes at the proximal (p < 0.05) and at the distal (p < 0.1) small intestine as compared to control animals. Mean concentration of the active ingredient in the stomach and proximal small intestine for the 2000 mg kg(-1) carvacrol diet was 521 and 5 mg kg(-1) fresh digesta, respectively, and for the 2000 mg kg(-1) thymol diets it ranged between 475 and 647 and between 13 and 24 mg kg(-1) fresh digesta, respectively. Cumulative absorption in the proximal small intestine was higher than 90% for all treatments and was not affected by formulation type. These data suggest that carvacrol and thymol can improve gut health, but evidence for clear antimicrobial effects towards the major culturable bacteria of the pig foregut is limited.

Fermented liquid feed for pigs.

Since the announcement of the ban on the use of antibiotics as antimicrobial growth promoters in the feed of pigs in 2006 the investigation towards alternative feed additives has augmented considerably. Although fermented liquid feed is not an additive, but a feeding strategy, the experimental work examining its possible advantages also saw a rise. The use of fermented liquid feed (FLF) has two main advantages, namely that the simultaneous provision of feed and water may result in an alleviation of the transition from the sow milk to solid feed and may also reduce the time spent to find both sources of nutrients, and secondly, that offering FLF with a low pH may strengthen the potential of the stomach as a first line of defence against possible pathogenic infections. Because of these two advantages, FLF is often stated as an ideal feed for weaned piglets. The results obtained so far are rather variable, but in general they show a better body weight gain and worse feed/gain ratio for the piglets. However, for growing-finishing pigs on average a better feed/gain ratio is found compared to pigs fed dry feed. This better performance is mostly associated with less harmful microbiota and better gut morphology. This review provides an overview of the current knowledge of FLF for pigs,dealing with the FLF itself as well as its effect on the gastrointestinal tract and animal performance.