The efficacy of two exogenous enzyme combinations and a multi-strain Bacillus probiotic (DFM) on the growth performance, nutrient digestibility, disa

SUMMARY Dietary fibre has traditionally been considered an energy-diluting component of laying hen diets. With low energetic values, and sometimes negative impacts on digesta viscosity and gut function, formulations have often aimed to minimise crude fibre contents. Increasing fibre contents can mean that the level of fat required to meet nutritional standards must be increased to account for the decrease in energy, with consequential impacts on feed handling. By contrast, recent research has shown that some dietary fibres can have beneficial effects on laying performance, driven by changes in digestibility, gut structure and function, as well as shifts in the gut microbiota. However, there is often a lack of clarity as to the quantity and type of fibre required to yield production benefits. Broadly, soluble fibres – while largely detrimental to nutrient digestibility – can act as prebiotics, favouring beneficial intestinal microbiomes, while insoluble fibres stimulate intestinal development and may have some preventative effects on feather pecking and cannibalism.

Tannins have long been considered ‘anti-nutritional’ factors in monogastric nutrition, shown to reduce feed intake and palatability. However, recent studies revealed that compared with condensed tannins, hydrolysable tannins (HT) appear to have far less impact on growth performance, but may be inhibitory to the total activity of caecal bacteria. This in turn could reduce microbial synthesis of skatole and indole in the hindgut of entire male pigs (EM). Thus, the objective of this study was to determine the impact of a group of dietary HT on growth performance, carcass traits and boar taint compounds of group housed EM. For the study, 36 Swiss Large White boars were assigned within litter to three treatment groups. Boars were offered ad libitum one of three finisher diets supplemented with 0 (C), 15 (T15) or 30 g/kg (T30) of HT from day 105 to 165 of age. Growth performance, carcass characteristics, boar taint compounds in the adipose tissue and cytochrome P450 (CYP) isoenzymes CYP2E1, CYP1A2 and CYP2A19 gene expression in the liver was assessed. Compared with C, feed efficiency but not daily gain and daily feed intake was lower (P<0.05) in T15 and T30 boars. Except for the percentage carcass weight loss during cooling, which tended (P<0.10) to be greater in T30 than C and T15, carcass characteristics were not affected by the diets. In line with the numerically lower androstenone level, bulbourethral and salivary glands of T30 boars were lighter (P<0.05) than of T15 with intermediate values for C. Indole level was lower (P<0.05) in the adipose tissue of T30 than C pigs with intermediate levels in T15. Skatole levels tended (P<0.10) to be lower in T30 and C than T15 pigs. Hepatic gene expression of CYP isoenzymes did not differ between-treatment groups, but was negatively correlated (P<0.05) with androstenone (CYP2E1 and CYP1A2), skatole (CYP2E1, CYP2A) and indole (CYP2A) level. In line with the numerically highest androstenone and skatole concentrations, boar taint odour but not flavour was detected by the panellists in loins from T15 compared with loins from C and T30 boars. These results provide evidence that HT affected metabolism of indolic compounds and androstenone and that they affected the development of accessory sex glands. However, the effects were too small to be detected by sensory evaluation.

Oxidative reactions in premixes or final-compound feed pose considerable challenges to the poultry industry, both in terms of rancidity reducing palatability and shelf life and in vivo oxidative stress negatively impacting animal performance. Whilst there has been broad awareness of feed oxidation for many years, recognition of the impact of oxidative stress on the poultry industry has grown in the past twenty years. The appearance of woody breast and associated muscle meat myopathies has led to a rapid increase in research output and awareness of in vivo oxidative reactions. Oxidative stress has been widely demonstrated to damage tissue, lipids, and DNA, and is thought to be linked to conditions such as leaky gut, coccidiosis, and ascites, amongst others. The use of dietary antioxidants has been found to both protect feed from oxidation and ameliorate some of the detrimental effects associated with oxidative stress, including improving performance, increasing antioxidant capacity, and mitigating the effects of heat and transport stress. Therefore, the aim of this review is to provide insight into the process of in-feed oxidation and in vivo oxidation including a summary of the benefits of different kinds of antioxidants in feed as well as their potential in vivo added value, based on findings reported within all scientific literature.

The potential of lecithin and lysolecithin to improve lipid digestion and growth performance was investigated in three experiments: 1. an in vitro model that mimics the intestinal conditio...