The work aimed to evaluate the effect of lactic acid bacteria, natamycin and hexanoic acid on the fermentation quality, aerobic stability and in vitro digestibility of total mixed ration (TMR) silages containing water bamboo sheath leaves. The treatments were as follows: (1) no additives (control, C), (2) lactic acid bacteria (L), (3) natamycin (N), (4) hexanoic acid (H), (5) lactic acid bacteria + natamycin (LN), (6) lactic acid bacteria + hexanoic acid (LH). Silos were opened and silages were evaluated to assess fermentation quality, aerobic stability and in vitro digestibility. All TMR silages were well-preserved as indicated by dominant lactic acid content, low ammonia nitrogen/total nitrogen, trace propionic acid and negligible butyric acid contents. All additives improved the fermentation quality and in vitro digestibility, evidenced by higher lactic acid/acetic acid ratio, lactic acid, acetic acid, water-soluble carbohydrate contents and lactic acid bacteria count, and lower pH, aerobic bacteria and yeast counts. The LN had the highest lactic acid, acetic acid, lactic acid/acetic acid ratio, in vitro gas production and in vitro digestibility. During aerobic exposure, the LN silage had the highest lactic acid and acetic acid contents, and the lowest pH among all TMR silages. The LN and LH prolonged aerobic stability, reaching 85.5 and 81.5 h, respectively. The LN is recommended to improve the fermentation quality, aerobic stability and in vitro digestibility of TMR prepared with water bamboo sheath leaves.

Seasonality and species are key aspects of the abiotic and biotic environment, respectively, that influence nutrient, phytochemical and antioxidant profiles of invasive alien plants leaf-meals. The current study investigated the effects of season on nutrient, amino acid, fatty acid, mineral, bioactive polyphenolic composition and antioxidant activity of Acacia mearnsii and A. dealbata leaf-meals. Overall, A. mearnsii leaf-meal harvested in the hot-dry-season had greater crude protein, ether extract, neutral detergent soluble fibre, 24 and 48 h in vitro neutral detergent fibre digestibility, macro-mineral contents, individual polyphenols, C18:1n9 and C18:2n6 compared to other leaf-meals. Regardless of the season, A. mearnsii leaf-meals had greater amino acid concentrations than A. dealbata leaf-meals. Hot-dry-season leaf-meals had a greater concentration of total flavonoids than the leaf-meals in the cool-wet-season irrespective of species. Antioxidant potency composite of the Acacia leaf-meals was in the order of A. dealbata × hot-dry-season > A. mearnsii × hot-dry-season > A. mearnsii × cool-wet-season > A. dealbata × cool-wet-season. The findings suggested that A. mearnsii leaf-meal harvested in the hot-dry-season has superior nutritional and polyphenolic profiles, which could support its use as a nutraceutical and preservative for the enhancement of ruminant production and product quality compared to other leaf meals.

The aim of this study was to determine the in vitro digestibility and in sacco disappearance of dry matter (DM) and neutral detergent fibre (NDF) in total almond hulls (TAH), pure almond hulls (PAH) or Debris. The TAH were used because there are no data on the effect of debris (non-hull material) on the nutritional value of almond hulls. Twelve samples of commercial almond hulls were used, with one subsample representing the TAH and the other subsample hand sorted to separate the hulls (PAH) from Debris. Gas production and Ankom Daisy method were used to determine in vitro digestibility, while two rumen-fistulated cows were used to measure in sacco disappearance of PAH and TAH. For in vitro digestibility, both PAH and TAH were more digestible and had greater gas production than Debris. The PAH had greater in vitro true digestibility on a DM basis and NDF digestibility at 48 and 72 h compared with TAH. Nonpareil hulls provided greater metabolizable energy (ME) concentration when compared with other almond varieties, with PAH supplying numerically more ME than TAH for both varieties. For in sacco disappearance, PAH had greater DM and NDF disappearance along with a greater rate of disappearance for NDF compared with TAH. This research demonstrated that Debris is highly indigestible; therefore, hulling, agronomic and harvesting practices should be focused on reducing Debris in commercial almond hulls to improve their nutritive value as a feedstuff for livestock.

Olive cake (OC) and cactus cladodes (CCs) are two alternative feed resources widely available in Mediterranean areas. Their use in ruminant diets was assessed according to their chemical composition, secondary compound levels and digestibility. The effects of the olive oil extraction period and process, and CCs age and sampling period were evaluated. OC was collected monthly, from November to January, from mills using either a mechanical press or 2-phase or 3-phase centrifugation processes. CCs were collected fortnightly according to age (young and mature) from April to June. Two-phase OC had the lowest content of dry matter (DM), the highest nitrogen-free extract (NFE) and total and hydrolysable tannins and was more rapidly fermentable. Mechanical press OC was the least digestible. OC DM, protein and NFE were affected linearly by the extraction period. Gas production (GP), in vitro digestibility parameters and dry and organic enzymatic digestibility changed with the extraction period. Therefore, OC chemical composition and in vitro digestibility depended mainly on the extraction process and period. Compared to mature CCs , young CCs contained more water, protein, ether-extract and phenolic compounds, but less ash and fibre. GP and digestibility parameters were not affected by age, but in vitro organic matter digestibility and microbial biomass production were higher in young cladodes. CCs chemical composition, GP and digestibility parameters were influenced by the collection period. Due to its limited nutritional quality, OC should be enriched in nitrogen, while CCs could be considered as highly valuable forage in ruminant diet.

Insects have been proposed as a high-quality, efficient and sustainable dietary protein source. The present study evaluated the protein quality of a selection of insect species. Insect substrates were housefly pupae, adult house cricket, yellow mealworm larvae, lesser mealworm larvae, Morio worm larvae, black soldier fly larvae and pupae, six spot roach, death's head cockroach and Argentinean cockroach. Reference substrates were poultry meat meal, fish meal and soyabean meal. Substrates were analysed for DM, N, crude fat, ash and amino acid (AA) contents and for in vitro digestibility of organic matter (OM) and N. The nutrient composition, AA scores as well as in vitro OM and N digestibility varied considerably between insect substrates. For the AA score, the first limiting AA for most substrates was the combined requirement for Met and Cys. The pupae of the housefly and black soldier fly were high in protein and had high AA scores but were less digestible than other insect substrates. The protein content and AA score of house crickets were high and similar to that of fish meal; however, in vitro N digestibility was higher. The cockroaches were relatively high in protein but the indispensable AA contents, AA scores and the in vitro digestibility values were relatively low. In addition to the indices of protein quality, other aspects such as efficiency of conversion of organic side streams, feasibility of mass-production, product safety and pet owner perception are important for future dog and cat food application of insects as alternative protein source.

In vitro gas production kinetics of six different substrates, pectin (PEC), xylan (XYL), starch (STA), cellulose (CEL), commercial compound feed (FEED; 201 g crude protein per kg, 155 g crude fibre per kg, 334 g neutral-detergent fibre (NDF) per kg and 190 g acid-detergent fibre (ADF) per kg) and an NDF prepared from commercial compound feed (NDFFEED) were determined using the caecum contents of weaned rabbits (36 days of age) and of rabbits at slaughter age (78 days of age) as inoculums. The cumulated gas production over 96 h of incubation was modelled with Gompertz model, and the kinetic parameters compared. The total potential gas production (parameter ‘B’ of the Gompertz model) was not affected (P>0.05) by the inoculum source, except with STA, where rabbits at slaughter weight had significantly higher total potential fermentability (314 ml/g dry matter (DM)) than those at weaning age (189 ml/g DM). Intensities of fermentation (maximum fermentation rate; MFR) of PEC (32.2 ml/h) and XYL (24.4 ml/h) were significantly greater in rabbits at weaning, while that of STA (45 ml/h) was significantly lower than at slaughter age (23.0, 14.3 and 14.0 ml/h for PEC, XYL and STA, respectively). The MFRs of CEL and NDFFEED were very similar between inoculum sources. In the first 10 h of fermentation which correspond to the normal retention time of the substrates in the caecum, the highest amount of gas was produced from PEC, followed by FEED and XYL. These substrates had a time of maximum fermentation rate (TMFR) at both rabbit ages short enough (8.0 and 9.5 h for PEC, 9.5 and 6.6 h for FEED, 13.7 and 14.2 h for XYL at weaning and at slaughter age, respectively) to be almost completely fermented in vivo.

Two in vitro experiments were conducted in order to determine if microbial fermentation of Eragrostis curvula hay is depressed by high levels of added tallow. Two levels of tallow, to reach 0.06 (T6) and 0.12 (T12) of the ether extract (organic matter basis) in food were compared with a control (T0, 25 g ether extract per kg). The first experiment studied the pattern of gas production. From 24 h onwards, gas volume for T0 was higher (P < 0.05) than for T6 and T12. However, lag time was shorter with tallow, probably because of utilization of the released glycerol. Fermentation of a similar amount of fat included in T6 and T12 as the only substrate (fat-6 and fat-12) depressed gas production compared with the blank, irrespective of fat level. In a second experiment, characteristics of microbial fermentation were studied, including volatile fatty acid (VFA) production, bacterial adhesion to fibrous particles (measured according to purine bases concentration) and polysaccharidase and glycosidase activities, at 6, 12, 24 and 48 h incubation. Total VFA was higher (P < 0.05) in T0 compared with T6 but not with T12. Acetate: propionate ratio diminished with tallow in the food. Higher total xylosidase (P > 0⋅05) and glycosidase (P < 0⋅001) activities were observed for T0 than for T6 and T12 and similar responses were observed regarding specific activities. Bacterial adhesion was not different between T0 and T6 but it was smaller in T12. The inhibition of microbial fermentation by tallow addition is more related to specific polysaccharidase and glycosidase activities, rather than to a depressed bacterial adhesion.

The accuracy with which several laboratory-based measurements predict the metabolizable energy (ME) value of whole-crop wheat (WCW) was determined. Twenty-six WCW forages differing in variety (cv. Slepjner, Hussar and Cadenza), maturity at harvest (milk, cheese and dough stages) and treatment applied (urea-treated, untreated or acid-based additive treated) were harvested in 2 years and conserved anaerobically in 200·1 barrels. The forages were then scanned using near infrared reflectance spectroscopy (NIRS) and analysed for chemical composition, in vitro rumen fluid-pepsin digestibility, in vitro neutral detergent-cellulase plus gamannase digestibility, in vitro fermentation gas production and in situ rumen degradability. ME was calculated using measured energy losses in faeces and urine and predicted energy losses as methane. The relationships between ME and the laboratory-based measurements were determined by regression. Gross energy was consistently the best predictor of ME (R2 = 0.53 and 0.86 in years 1 and 2 respectively). However the autocorrelation involved, militates against the prediction of ME from gross energy. None of the chemical constituents or biological techniques gave a good, robust prediction of ME. However, an NIRS calibration developed using the WCW samples was highly correlated (R2 = 0.68) with ME. This work therefore suggests that traditional laboratory-based, food evaluation techniques are unsuitable for predicting the ME content of WCW but that NIRS holds promise.

A study was carried out to compare the fermentation parameters and kinetics of digestion of a range of different foods in the rumen of two breeds of sheep (Churra and Merino). Ten mature sheep (five Churra and five Merino), each fitted with a rumen cannula, were used in this study. In situ rumen degradability of both dry matter (DM) and cell wall was greater in Churra than in Merino sheep, the breed differences being significant for most of the foods used in the study (P < 0·05). These differences were greater when the foods had a higher cell wall concentration and this could be related to differences in the ruminal environment. However, when the foods were incubated with rumen fluid their in vitro organic matter (OM) degradability was similar in both breeds. Rumen pH was higher (P < 0·05) and ammonia concentrations were lower (P < 0·05) in Churra than in Merino sheep. Rumen volatile fatty acid concentrations tended to be higher in Merino than in Churra sheep, though differences were only significant just before feeding (P < 0·05). The ratio acetate: propionate was higher in the Churra than Merino breed before and 12 h after feeding (P < 0·05). Protozoa numbers in rumen liquid were similar for both genotypes. The greater degradation of forages in the rumen of Churra sheep is discussed in relation to the possible higher activity of fibre-degrading micro-organisms and the greater buffering capacity of the rumen contents against fermentation acids, which could result in more favourable conditions for the microbial degradation of foods in the rumen.

The need to complement in vitro gas production measurements with residue determination is demonstrated by the recalculation and reassessment of published data on in vitro gas production, in sacco degradabilities and voluntary dry matter intake (DMI). The in sacco degradability — gas volume ratio was determined at 24 and 48 h of incubation, termed partitioning factor (PF) and combined with rate and extent parameters of in sacco degradability and in vitro gas production to predict DMI. In vitro gas production and in sacco degradability characteristics (a + b) and c as described by the equation y = a + b(1−ect) explained 0·373 and 0·668 respectively of the variation in DMI of 19 legume and grass hays. The complementation of gas production parameters by the PF24 increased the R2 value to 0·744 with PF24 accounting for 0·407 of the variation in DMI, the rate of gas production (c) for 0·218 and the extent of gas production (a + b) for 0·119 of the variation in DMI. As a single parameter, PF48 showed the highest correlation (R2 = 0·597) with DMI but the combination of PF4S with rate and extent of in sacco or in vitro gas production measurements did not improve the correlation further, probably due to an intercorrelation between rates of fermentation and PF4S. Hays which were degraded at faster rates had higher PF values indicating proportionally higher microbial yield and lower short-chain fatty acid production per unit substrate degraded. Generally, hays with high in sacco degradabilities but proportionally low gas production i.e. hays with high PF values showed higher DMI.

Ten hays harvested at three stages (early bloom MB, mid bloom MB or in seed) made from lucerne (Medicago sativaj, sweet clover (Melilotus segetalis), Persian clover (Trifolium resupinatum) and pre-bloom (PB) Italian ryegrass (Lolium multiflorum var.), were offered ad libitum to four Merino male sheep and daily intake (g dry matter (DM) per kg M0·75) and DM apparent digestibility (DMD) were measured. In sacco DM degradation (g per 100 g DM), gas production (ml per 200 mg DM), in vitro digestibility and fibre composition (g/kg DM) of the hays were also studied. Gas production or DM degradation were calculated at 6, 12, 24, 48, 72 or 96 h and their kinetics were described using the equation p = a + b(1 - e-ct). Intake and in vivo DMD of the hays were variable (P < 0·01). Lucerne EB and Persian clover (all stages) had the highest nutritive value, whereas sweet clover (all stages) had the lowest. Apart from neutral-detergent fibre, which was only related to intake (r = -0·68; P < 0·05), chemical components and in vitro digestibility were poorly (P > 0·05) related to animal performance. Between 12 and 96 h incubation, intake and in vivo DMD were better related to DM degradation (r = 0·79 to 0·83; r = 0·61 to 0·77) than to gas production (r = 0·73 to 0·80; r = 0·58 to 0·78). Prediction of intake and in vivo DMD from the (a + b) values did not provide a great advantage over using some of the static values of gas production or DM degradation.

Multiple regression using separated kinetics of degradation resulted in highest accuracy for predicting intake and apparent digestibility from gas production (R2 = 0·63; R2 = 0·78) and nylon bag degradability (R2 = 0·77; R2 = 0·89). It was concluded that the gas test has good potentiality as it was capable of predicting not only apparent digestibility, but also intake to a level close to that of the nylon bag technique.