Use of faeces as an alternative inoculum to caecal content to study in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus)

1. In order to find an alternative source of inoculum to caecal content for studying the in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus), caecal content and faeces of 4 male birds were used as inocula for an in vitro gas production trial. 2. About 1 g of each of 5 substrates (maize silage, CS; alfalfa hay, AH; barley, BG; soybean meal, SM; beet pulp, BP) was weighed, in quadruplicate per inoculum, in 120 ml flasks; 75 ml of anaerobic medium and 4 ml of reducing solution were added and flasks were kept at 39 degrees C. Caecal content and faeces were diluted respectively 1 : 2 (CI) and 1 : 4 (FI) with an anaerobic medium and were injected into the respective flasks (10 ml). 3. Gas production was recorded 22 times up to 120 h of incubation and fermentation characteristics (for instance, degraded organic matter, OMd; potential gas production, A; maximum fermentation rate, Rmax; time at which it is reached, Tmax; pH; volatile fatty acid, VFA; ammonia) were studied for each inoculum and substrate. 4. CI and FI showed significant differences in Tmax (16.37 vs 18.47 h, respectively), propionic (16.47 vs 12.07 mmoles/l) and butyric acid (6.50 vs 7.98 mmoles/l) and ammonia concentration (17.18 vs 19.95 mmoles/l). The substrates, according to their chemical composition, showed different fermentation characteristics. However, the regression equations able to estimate some fermentation characteristics of the caecum from those of faeces were statistically significant and showed R2-values ranging from 0.87 to 0.99. 5. The differences in fermentation pathways of the two inocula did not appear to influence the rate and extent of OM digestion. Faecal fermentation predicted rates and extent of OM digestion by caecal fermentation in ostriches; consequently, the faeces could be considered as an alternative to caecal content to study feed digestibility in the species, although there is a need to undertake further research.     

In vitro fermentation patterns and methane production of sainfoin (Onobrychis viciifolia Scop.) hay with different condensed tannin contents

Sainfoin (Onobrychis viciifolia Scop.) is a perennial legume recently reappraised for some positive characteristics leading to highly satisfactory animal performance. Sainfoin’s characteristics may be partly explained by the presence of moderate levels of condensed tannins (CTs) able to protect dietary protein from microbial degradation in the rumen. Decreased CH₄ emissions have been reported for ruminants consuming CT‐containing forage. The aim of this study was to evaluate the effects of CT content on the in vitro fermentation characteristics and kinetics and methane production of four samples of O. viciifolia cut at different phenological stages. Sainfoin hays and one sample of alfalfa hay were incubated at 39°C in anaerobiosis using the in vitro gas production technique. The chemical composition, tannin content and fermentation characteristics and kinetics of sainfoin samples were significantly affected by phenological stage. After 48 h, the CH₄ production in sainfoin hays showed a tendency to increase with the advancement of phenological stage [from 38·6 to 49·8 mL g⁻¹ of degraded organic matter (OM)]. The best period to cut sainfoin for hay making is between early and late flowering, when the forage combines high OM digestibility, low CH₄ production and more efficient microbial fermentation.     

Fermentation kinetics of sainfoin hay with and without PEG

The in vitro gas production technique was applied to evaluate the biological activity of tannins in sainfoin (Onobrychis viciifolia Scop.) hay cut at four progressive phenological stages. The buffalo (Bubalus bubalis) rumen fluid was used as inoculum, polyethylene glycol (PEG) was added as specific binding agent and an alfalfa hay (AH) was used as control. All samples were analysed for chemical composition and condensed tannin (CTs). According to the phenological stage of sainfoin, crude protein gradually decreased [from 219 to 122 g/kg dry matter (DM)] and neutral detergent fibre (NDF) increased (from 391 to 514 g/kg DM). Condensed tannins showed the highest value at the first phenological stage [31.5 mg catechin equivalents (CE)/g DM], and their level significantly decreased at the subsequent growth stages. Gas production and fermentation rate were significantly affected by substrate type and PEG addition. The first stage of sainfoin showed the lowest value of gas and volatile fatty acids production and the slowest fermentation kinetics compared with the other samples, when incubated without PEG, because of the CTs effect. The incubation with PEG improved the fermentation process of the first stage of sainfoin, but no effect was registered on AH, where CTs were not detected. Among the sainfoin samples, the slowest kinetics with PEG was observed in the hay harvested at the fourth stage, probably due to its chemical composition. The use of PEG allowed to verify the effect of tannins on the in vitro fermentation characteristics of sainfoin hay.     

Comparison of nutritional and antinutritional traits among different species (Lupinus albus L., Lupinus luteus L., Lupinus angustifolius L.) and varieties of lupin seeds

In order to promote the use of lupin in pig nutrition, in this research the nutritional characteristics (i.e. dietary fibre, alkaloid and fatty acid profile) and the in vitro gas production of 12 lupin varieties grown in the Mediterranean basin and belonging to three lupin species (Lupinus albus, Lupinus angustifolius and Lupinus luteus) were assessed. Four varieties of L. albus (Asfer, Lublanc, Lutteur and Multitalia) were grown in South Campania. Three varieties of L. luteus (Dukat, Mister and Taper), three of L. angustifolius (Jindalee, Sonet and Wonga) and two of L. albus (Rosetta and Luxor) were grown in Eastern Sicily. Lupinus albus varieties showed interesting nutritional and dietetic characteristics (i.e. high protein and low fibre content); the lipid fraction, rather elevated, is well represented by monounsaturated fatty acids (544 g/kg), whereas saturated fatty acids (SFAs) are less represented (167 g/kg) and the n‐3/n‐6 ratio (0.510) is the most favourable. Lupinus luteus varieties presented the most remarkable dietetic aspects, in terms of polyunsaturated fatty acid (PUFA) content (569 g/kg), n‐6 PUFA series (490 g/kg), UFA/SFA (5.24) and PUFA/SFA (3.56) ratios and atherogenic (0.059) and thrombogenic (0.100) indices and very low alkaloid content (1.07 mg per 100 g). Lupinus angustifolius varieties showed the least interesting nutritional and dietetic characteristics: low protein and fat content, high fibre level, high SFA amount (248 g/kg) and the lowest favourable nutritional indices (IA: 0.164 and IT: 0.334). Regarding the fermentation process, in L. albus, the tendency to increase the rate of gas production during the early stages of fermentation suggests that the high presence of alkaloids did not affect the in vitro degradability, production of short‐chain fatty acids and fermentation process, probably due to their concentration and/or water solubility. Lupinus angustifolius and L. luteus showed intermediate and slightly worse in vitro fermentation patterns respectively. From a nutritional and dietetic point of view, lupin may represent an interesting alternative to soya bean in pig feeding.