IntroductionEnteric methane production represents an inefficiency in ruminant systems and contributes to greenhouse gas emissions.MethodsTo mitigate ruminal methanogenesis, this study performed a systematic comparative valuation of the dose-dependent effects of two distinct additive categories: methanogenesis inhibitors (MI) such as 3-nitroxipropanol (3NOP), bromoform (BRO) and iodoform (IOD), as well as alternative dihydrogen sinks (dHS) including fumaric acid (FA), encapsulated slow-release fumaric acid (EFA) and phloroglucinol (PHG). The experimental arrangement followed a dose-response design where each additive was incubated at three concentrations (low, medium, and high) for 24 hours with buffered rumen fluid and a total mixed ration as substrate. Control (CON) and blank (BLK) samples were included. IOD and BRO were dissolved in ethanol as they are not soluble in water. To take into account the ethanol effect on fermentation parameters, ethanol-amended CON and BLK were added to correct for BRO and IOD values. Total gas production (TGP) was calculated from pressure readings using the ideal gas law. The volatile fatty acid (VFA) profile and the methane (CH4) and hydrogen (H2) concentrations in the headspace were evaluated using gas chromatography. Statistical analysis included dosage as a fixed effect and run as a random effect.ResultsThe addition of 3-NOP caused a quadratic decrease in CH4 production and a corresponding linear increase in H2. However, increasing doses of 3-NOP reduced both TGP and total VFA (TVFA) while shifting fermentation toward propionate production. Among the MI, only IOD maintained TVFA production, linearly reducing methanogenesis and TGP, while increasing H2 availability. BRO strongly inhibited CH4 at all doses and increased H2 production, while significantly reducing TGP and TVFA. Regarding dHS, no treatment affected H2 accumulation. Both FA and EFA linearly decreased acetate and increased propionate proportions without influencing TVFA. Notably, EFA, unlike FA, linearly increased TGP and reduced CH4 proportion. In contrast, PHG increased both TGP and TVFA, favoring acetate formation.ConclusionThe study identified specific dose-response behavior of MI and dHS, highlighting the modulation of different fermentative products.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

This study evaluated the effects of different SID lysine levels on growth performance, feed costs, and nitrogen excretion of growing pigs raised for dry-cured ham production. Ninety-six Goland-C21 x Camborough-43 pigs (initial body weight, BW: 44.5 +/- 3.8 kg) were allocated to four dietary treatments (2 pens/treatment, 12 pigs/pen) with low (L: 6.9, 6.0, 4.2 g/kg), medium-low (ML: 7.8, 6.9, 5.2 g/kg), medium-high (MH: 8.3, 7.8, 6.0 g/kg), or high (H: 9.3, 8.3, 6.9 g/kg) SID lysine across the growing (90-118 days), early finishing (119-132 days), and late finishing (133-233, days) phases. Automated feeding stations recorded individual feed intake. Backfat (BF) thickness and BW were measured at five time points. Nitrogen excretion was estimated from intake, retention, and atmospheric losses. Data were analysed using the PROC MIXED procedure in SAS; the model included dietary treatment, sex, and their interaction as fixed effects and pen nested within treatment as a random effect. Compared with L pigs, ML pigs showed similar feed intake and final BF depth but achieved higher (p < .05) final BW, greater average daily gain, and improved gain-to-feed ratio, while reducing feed costs (1.63 vs 1.77 per kg BW gain) without increasing nitrogen excretion. Growth performance of ML pigs was comparable to that of MH and H pigs; however, ML diets resulted in the lowest feed costs and nitrogen excretion. These findings suggest that a medium-low SID lysine diet is sufficient for this pig population, effectively supporting growth performance while reducing feeding costs and environmental impact.

This study investigated the partitioning of metabolisable energy (ME) and standardised ileal digestible (SID) lysine in 96 Goland-C21 × Camborough-43 pigs, raised from 32 to 196 kg of body weight (BW) and fed voluntarily diets containing low (L), medium-low (ML), medium-high (MH), and high (H) SID lysine levels. Diets were formulated to provide decreasing SID lysine concentrations with increasing ages: early (90–118 d), late growing (119–146 d), and finishing (147–251 d). Individual feed intake was recorded using automated feeders, while BW and P2 backfat thickness were measured at the start and end of each interval to estimate protein (Pd) and lipid (Ld) deposition. Maintenance ME (MEm) was calculated by subtracting the energy required for Pd and Ld from total ME intake and scaled to BW0.60. Marginal SID lysine intake was determined as the difference between intake and maintenance requirements, based on the InraPorc model. The efficiency of SID lysine utilisation was calculated as the ratio of lysine deposited in Pd to marginal SID lysine intake. The L treatment provided insufficient SID lysine, resulting in lower final BW (p = 0.004), Pd (p = 0.003), and Ld (p = 0.023) compared to ML. However, ML, MH, and H treatments showed no significant differences. MEm averaged 0.961 MJ/kg0.60 BW, and lysine utilisation efficiency peaked at 0.68 in L pigs, aligning with InraPorc predictions. These findings support the applicability of the InraPorc model to pigs above 140 kg and offer updated SID lysine requirements across growth intervals.

Condensed tannins (CT) are plant polyphenols that can affect feed digestibility and are potentially able to reduce enteric methane emissions in ruminants. In this in vivo trial with 8 lactating goats, we investigated the effects of 4 levels of inclusion of a commercial CT extract from quebracho (0, 2, 4, 6% on DM basis; C, Q2, Q4, Q6, respectively). The experimental design was a repeated 4 × 4 Latin square with 28-d periods (24 d of diet adaptation and 4 d of sample collection) using metabolic cages and 4 open circuit respiration chambers. The inclusion of CT in the diets did not affect the dry matter intake (DMI) but caused a linear decrease in diet digestibility, with reductions up to −11% for dry matter (DM), −21% for crude protein (CP), −23% for neutral detergent fiber (aNDFom), and −13% for gross energy, when comparing the Q6 and C diets. However, ruminal total volatile fatty acids (VFA) concentration was not affected by CT, although there were changes in VFA proportions. Milk yield (g/d) was highest for Q4 (3371) and lowest for Q6 (3066). In terms of milk composition, CT induced a linear reduction of fat and CP concentrations. The reduction in CP digestibility resulted in a linear reduction in the milk urea level, up to −37% with Q6. Positively, CT linearly reduced the somatic cells count expressed as linear score. The feed efficiency was linearly decreased by CT inclusion. Furthermore, a shift from urinary to fecal nitrogen excretion was observed with CT. The retained nitrogen was always negative (on average −1.93 g/d). The methane yield (on average 19.2 g CH4/kg DMI) was linearly reduced by CT inclusion, up to −18% with Q6. Regarding the CH4 intensity, CT induced a linear reduction when expressed per kg of milk, but not per kg of fat and protein corrected milk. Moreover, the CH4 production per kg of digestible aNDFom was linearly increased by CT. The metabolizable energy intake (MEI) was not affected by the treatments, but the metabolizability (q = MEI/gross energy intake) was reduced as CT inclusion increased. From the results of the present study, it turned out that CT have a negative impact on feed digestibility and feed use efficiency. Condensed tannins can lower CH4 emissions from ruminants; however, the main mechanism of action is likely the decrease in feed digestibility. Furthermore, CT did not improve the N use efficiency. According to these findings, the positive environmental impacts of CT are only related to the shift from urinary to fecal N excretion.

The administration of Bacilli to dairy cows exerts beneficial effects on dry matter intake, lactation performance, and milk composition, but the rationale behind their efficacy is still poorly understood. In this work, we sought to establish whether cellulases and xylanases, among the enzymes secreted by B. subtilis, are involved in the positive effect exerted by Bacilli on ruminal performance. We took advantage of two isogenic B. subtilis strains, only differing in the secretion levels of those two enzymes. A multi-factorial study was conducted in which eight feed ingredients were treated in vitro, using ruminal fluid from cannulated cows, with cultures of the two strains conveniently grown in a growth medium based on inexpensive waste. Feed degradability and gas production were assessed. Fiber degradability was 10% higher (p < 0.001) in feeds treated with the enzyme-overexpressing strain than in the untreated control, while the non-overexpressing strain provided a 5% increase. The benefit of the fibrolytic enzymes was maximal for maize silage, the most recalcitrant feed. Gas production also correlated with the amount of enzymes applied (p < 0.05). Our results revealed that B. subtilis cellulases and xylanases effectively contribute to improving forage quality, justifying the use of Bacilli as direct-fed microbials to increase animal productivity.

AbstractA large body of literature has accumulated on the beneficial impact of the administration ofBacillito dairy cows, particularly on dry matter intake, lactation performances and milk composition. In this work we sought to establish whether the ability ofB. subtilisto secrete cellulase and xylanase enzymes could be involved in the positive effect exerted by these bacteria.Several feed ingredients were treated with twoB. subtilisstrains only differing for the amount of secreted cellulosolytic and xylanolytic enzymes, and feed quality was assessed. We found thatin vitrofibre digestibility correlated with the activity of those enzymes. Our results revealed thatB. subtiliscellulases and xylanases can effectively improve forage quality, providing a scientific rationale on the use ofBacillias forage supplements to improve animal productivity. Moreover, a particular care was taken in designing a sustainable and economically viableBacillus-based additive preparation process.

The administration of Bacilli to dairy cows exerts a beneficial effect on dry matter intake, lactation performances and milk composition. In this work, two isogenic strains, only differing in the se-cretion level of cellulolytic and xylanolytic enzymes, were compared to establish whether B. subtilis cellulase and xylanase enzymes are involved in the positive effect exerted by these bacteria on animal nutrition. Conveniently, bacteria were grown in a newly designed growth medium based on an inexpensive waste. A multi-factorial study was conducted in which eight feed in-gredients were treated in vitro, using ruminal fluid from cannulated cows, with cultures of the two B. subtilis strains. Feed digestibility and gas production, a parameter linked to feed fermentability, were assessed. Fiber degradability was significantly higher in feeds treated with the en-zyme-overexpressing strain (10% and 5% higher than control treatment with B. subtilis-free media and the parent strain, respectively). This effect was accentuated for the most recalcitrant feeds, in which the benefits of cellulolytic and xylanolytic enzymes were maximized. Fermentability also benefited by the treatment with the enzyme-overexpressing strain, although the trend observed in gas production didn’t reach statistical difference between the two strains, and only minor changes in fermentation profiles were detected. Our results revealed that B. subtilis cellulases and xylanases effectively contribute to improving forage quality, supporting the use of Bacilli as fodder sup-plements to increase animal productivity.

A large body of literature has accumulated on the beneficial impact of the administration of Bacilli to dairy cows, particularly on dry matter intake, lactation performances and milk composition. In this work we sought to establish whether the ability of B. subtilis to secrete cellulase and xylanase enzymes could be involved in the positive effect exerted by these bacteria.Several feed ingredients were treated with two B. subtilis strains only differing for the amount of secreted cellulosolytic and xylanolytic enzymes, and feed quality was assessed. We found that in vitro fibre digestibility correlated with the activity of those enzymes. Our results revealed that B. subtilis cellulases and xylanases can effectively improve forage quality, providing a scientific rationale on the use of Bacilli as forage supplements to improve animal productivity. Moreover, a particular care was taken in designing a sustainable and economically viable Bacillus -based additive preparation process.### Competing Interest StatementThe authors have declared no competing interest.

The study aimed to evaluate Intergovernmental Panel on Climate Change (IPCC) Tier 2 (2006 and 2019) to predict enteric CH4 emissions from lactating cows fed Mediterranean diets. The effects of the CH4 conversion factor (Ym; CH4 energy loss as a percentage of gross energy intake) and digestible energy (DE) of the diet were evaluated as model predictors. A data set was created using individual observations derived from 3 in vivo studies on lactating dairy cows housed in respiration chambers and fed diets typical of the Mediterranean region based on silages and hays. Five models using different Ym and DE were evaluated following a Tier 2 approach: (1) average values of Ym (6.5%) and DE (70%) from IPCC (2006); (2) average value of Ym (5.7%) and DE (70.0%) from IPCC (2019; 1YM); (3) Ym = 5.7% and DE measured in vivo (1YMIV); (4) Ym = 5.7 or 6.0%, depending on dietary NDF, and DE = 70% (2YM); and (5) Ym = 5.7 or 6.0%, depending on dietary NDF, and DE measured in vivo (2YMIV). Finally, a Tier 2 model for Mediterranean diets (MED) was derived from the Italian data set (Ym = 5.58%; DE = 69.9% for silage-based diets and 64.8% for hay-based diets) and validated on an independent data set of cows fed Mediterranean diets. The most accurate models tested were 2YMIV, 2YM, and 1YMIV with predictions of 384, 377, and 377 (g of CH4/d), respectively, versus the in vivo value of 381. The most precise model was 1YM (slope bias = 1.88%; r = 0.63). Overall, 1YM showed the highest concordance correlation coefficient value (0.579), followed by 1YMIV (0.569). Cross-validation on an independent data set of cows fed Mediterranean diets (corn silage and alfalfa hay) resulted in concordance correlation coefficient of 0.492 and 0.485 for 1YM and MED, respectively. The prediction of MED (397) was more accurate than 1YM (405) in comparison with the corresponding in vivo value of 396 g of CH4/d. The results of this study showed that the average values proposed by IPCC (2019) can adequately predict CH4 emissions from cows fed typical Mediterranean diets. However, the use of specific factors for the Mediterranean area, such as DE, improved the accuracy of the models.

Both condensed and hydrolysable tannins (CTs and HTs, respectively) have the ability to reduce enteric CH4 production in ruminants. However, the precise mechanism of action is not fully understood. Among the proposed hypotheses are the reduction of ruminal digestibility, direct control action on protozoa, reduction of archaea, and a hydrogen sink mechanism. In this in vitro study, which simulated rumen fermentation, two additives, one containing CTs (70% based on DM) from quebracho and one with HTs (75% based on DM) from chestnut, at four levels of inclusion (2, 4, 6, 8% on an as-fed basis) were added to the fermentation substrate and tested against a negative control. Both types of tannins significantly reduced total gas (GP) and CH4 (ml/g DM) production during the 48 h of incubation. The lower GP and CH4 production levels were linked to the reduction in dry matter digestibility caused by CTs and HTs. Conversely, no significant differences were observed for the protozoan and archaeal populations, suggesting a low direct effect of tannins on these rumen microorganisms in vitro. However, both types of tannins had negative correlations for the families Bacteroidales_BS11 and F082 and positive correlations for the genera Prevotella and Succinivibrio. Regarding the fermentation parameters, no differences were observed for pH and total volatile fatty acid production, while both CTs and HTs linearly reduced the NH3 content. CTs from quebracho were more effective in reducing CH4 production than HTs from chestnut. However, for both types of tannins, the reduction in CH4 production was always associated with a lower digestibility without any changes in archaea or protozoa. Due to the high variability of tannins, further studies investigating the chemical structure of the compounds and their mechanisms of action are needed to understand the different results reported in the literature.

The high reliance of the European livestock sector on imported soybean meal (SBM), especially from South America, poses environmental problems, like greenhouse gas emissions for transportation and land-use change with the loss of carbon stock and biodiversity. Aim of the present study was to evaluate the partial substitution of SBM with whole-plant soybean silage in the diet of dairy cows. Thirty-six lactating Holstein cows were arranged according to a change-over design, with 2 weeks of adaptation and 5 days of sampling per period. A control diet (CON) was based on maize silage and SBM, representing 10.7% of total dry matter (DM). In a soybean silage diet (SBS) 35% (on DM basis) of SBM was replaced by soybean silage. The dietary treatment did not affect DM intake, milk production, and dairy efficiency while cows fed SBS resulted in lower milk crude protein (3.43 vs. 3.55%, p < .001) and higher milk urea (30.5 vs. 28.7 mg/dL, p = .002), in comparison with CON. Nutrients digestibility was lower for SBS than CON; particularly fibre digestibility was 31.5 vs. 38.8% (p < .001). The efficiency of nitrogen utilisation was higher for CON than SBS (32.7 vs. 31.3%, p = .003). Soybean silage did not penalise feed intake and milk production. However, to fully exploit this forage, digestibility, and nitrogen utilisation efficiency should be improved.Highlights Soybean silage can substitute one-third of soybean meal in dairy cow diet Soybean silage inclusion in the diet did not affect milk yield and DMI Soybean silage inclusion in the diet reduced N use efficiency

The current nutrient recommendations focus on pigs fed ad libitum up to 140 kg in body weight (BW). It remains unclear whether this applies to pigs weighing above 140 kg in BW under different rearing conditions. This study aimed to estimate protein (Pd) and lipid (Ld) depositions and the metabolizable energy (ME), standardized ileal digestible lysine (SID lysine) requirement and partitioning in 224 C21 Goland pigs (90–200 kg in BW). The control pigs (C) received diets limiting ME up to 170 kg in slaughter weight (SW) at 9 months of age (SA); older (OA) pigs had restricted diets limiting ME and SID lysine up to 170 kg in SW at >9 months SA; younger (YA) pigs were fed nonlimited amounts of ME and SID lysine up to 170 kg in SW at <9 months SA; and greater weight (GW) pigs were fed as the YA group, with 9 months SA at >170 kg in SW. The estimated MEm averaged 1.03 MJ/kg0.60. An 11% increase in MEm was observed in OA pigs compared to the controls. Energy restriction had negligible effects on the estimated MEm. The marginal efficiency of SID lysine utilization for Pd averaged 0.725, corresponding to a SID lysine requirement of 9.8 g/100 g Pd.

The weaning period is a stressful period for the gastrointestinal tract (GIT) of piglets. This work aims to evaluate the effects of the commercial polyphenol-based product GreenFIS® on: (1) GIT health and performance of 60 weaned piglets; (2) digestibility in 18 growing pigs. Three diets were tested: a control diet (C), C plus 2.5 g of GreenFIS®/kg C (T1), and C plus 5 g of GreenFIS®/kg C (T2). After the post-weaning trial three piglets per treatment were sacrificed for the GIT histological analysis. No differences between diets were recorded in terms of growing performance or clinical and biochemical blood parameters. The GIT histological analysis did not show any indicators of inflammation for any of the groups. The feces of the two extreme treatments (C and T2) were analyzed for microbiota, revealing a greater presence of the Ruminococcus bromii group, positively associated with starch degradation, in T2. In the second experiment six pigs per treatment were randomly chosen for the digestibility study. The inclusion of GreenFIS® at both levels led to a higher fecal digestibility of gross energy (86.2%, 89.1%, and 89.5%, for C, T1, and T2, respectively) and crude protein (87.0%, 90.2%, and 90.0%). In conclusion, the additive did not improve, in the excellent experimental hygienic conditions, the gut health, but it did increase nutrient digestibility.

The interest in using byproducts from agro-food industries as a rearing substrate for insects is increasing rapidly. We investigated the influence of byproducts of vegetal origin (okara-a byproduct of soy milk production, maize distillers with solubles, brewer's grains), used as rearing diet for black soldier fly larvae (BSFL), on the following parameters: biomass production, substrate reduction (SR), nutritional profile and in vitro digestibility, and larval gut microbiota. Hen diet was used as a control substrate. The highest larval biomass was collected on maize distillers, whereas the highest SR was observed on okara. The rearing substrate affected ash, ether extract, and chitin larval content. The BSFL reared on okara were characterized by a lower lauric acid content (17.6% of total fatty acids). Diets also influenced in vitro crude protein digestibility (%) for monogastrics, with the highest values for BSFL reared on maize distillers (87.8), intermediate for brewer's grains and okara BSFL, and the lowest for hen BSFL (82.7). The nutritive value for ruminants showed a lower Net Energy for lactation for BSFL reared on hen diet than okara and dried maize distillers BSFL. The different byproducts showed an influence on the larval gut microbiota, with a major bacterial complexity observed on larvae fed with the hen diet. The neutral detergent fiber concentration of dietary substrate was negatively correlated with Firmicutes and Actinobacteria relative abundance. Insects valorized byproducts converting them into high-value larval biomass to be used for feed production. The results evidenced the effects of the tested byproducts on the measured parameters, underling the chemical composition importance on the final insect meal quality.

The effect of whole linseeds or hemp seeds on milk production, energy and nitrogen balance, and methane emission was studied in 12 Alpine goats using respiration chambers. Diets tested were a control diet (C) and two diets supplemented with whole linseeds (L) or hemp seeds (H) at 9.3% on a dry matter (DM) basis. DM intake was similar among treatments, whereas DM and organic matter digestibility were lower for L compared to C. Milk yield (2.30 kg/d on average) and rumen fermentation profile were not affected by treatments. Treatment also did not affect the milk composition, with the exception of fat, which was higher in H and L compared to C (4.21, 3.94, and 3.20%, respectively). Oilseed supplementation caused a reduction in the concentration of de novo fatty acids (FA) (41.1, 48.8, and 64.1% of FA, for L, H, and C, respectively). Moreover, L and H diets reduced the sum of saturated FA, and increased monounsaturated FA, whereas only the L diet increased the concentration of polyunsaturated FA. Regarding methane production, and nitrogen and energy balances, no differences were registered among the diets. Our research indicates that including whole linseeds and hemp seeds in the dairy goat diet is an effective strategy for increasing milk fat content and positively modifying the milk FA composition, without a change in nitrogen and energy balances, but also without a reduction in enteric methane emission.

Undigested neutral detergent fibre (uNDF) is commonly used as an internal marker for the estimation of diet digestibility in ruminants. This work aimed to verify (i) whether the in vivo method with uNDF could be used to evaluate diet digestibility in growing pigs, and (ii) whether pre-treating the samples with neutral detergent solution (NDS) and α-amylase improves the accuracy of the estimates. Samples from a previously published work of two diets with known in vivo digestibility values estimated by the total faecal collection method and 16 individual samples of faeces were used. For each sample, four Ankom F57 bags were weighed. Before the incubation, two F57 bags were pre-treated with NDS and α-amylase. All the samples were incubated for 240 h in the Ankom DaisyII incubator and then analysed for their uNDF contents. Dry matter, organic matter, and neutral detergent fibre digestibilities were estimated using the uNDF contents, and the results were compared with those of the former study. The digestibility values obtained using the uNDF method with pre-treatment were not statistically different from those determined with the total faecal collection. On the contrary, the uNDF method without the pre-treatment could not satisfactorily predict the digestibilities of pig diets.

In view of better environmental sustainability, livestock diets must not exceed protein requirements, as often happens with lactating goats reared in semi-intensive systems. The aim of this experiment was to verify in real-breeding conditions the influence of two diets with different protein contents (% crude protein (CP) on dry matter (DM)): 16.0 (high-protein diet; HP) vs 12.2 (low-protein diet; LP) on milk production in dairy goats. The diets differed only in the replacement-in the LP diet-of 250 g soybean meal with 250 g maize grain meal. Twenty-three Alpine goats were divided into two groups and used in a cross-over feeding trial for 2 months. Animals were weighed at the beginning of each month of the trial, and feed intake and milk yield and composition were recorded weekly. HP and LP did not differ statistically for milk yield and composition (3.32 vs 3.42 kg milk/d, 3.21% vs 3.27% fat, 3.31% vs 3.27% protein for HP and LP, respectively), but the HP diet determined a higher milk urea content (51.2 vs 36.6 mg/dL, p < 0.001) and a worse efficiency of nitrogen utilization (28.0% vs 37.2%). In conclusion, the LP diet resulted in a reduction of urinary nitrogen excretion by 28% and of the feed cost by about 10%.

Eight lactating Italian Friesian cows were housed in individual respiration chambers in a repeated Latin square design to determine their dry matter intake (DMI) and their milk and methane production, as well as to collect the total feces and urine to determine the N and energy balances. Four diets, based on the following forages (% of dry matter, DM), were tested: corn silage (CS, 49.3), alfalfa silage (AS, 26.8), wheat silage (WS, 20.0), and a typical hay-based Parmigiano Reggiano cheese production diet (PR, 25.3 of both alfalfa and Italian ryegrass hay). The greatest DMI was observed for cows fed PR (23.4 vs. 20.7 kg/d, the average of the other 3 diets). The DM digestibility was lower for PR (64.5 vs. 71.7%, the average of the other diets). The highest ash-free neutral detergent fiber digestibility values were obtained for CS (50.7%) and AS (47.4%). In the present study, no differences in milk production were observed between diets, although PR showed a higher milk yield trend. The highest milk urea N concentration (mg/dL) was found for the cows fed the WS diet (13.8), and the lowest was observed for the cows fed AS (9.24). The highest milk urea N concentration for the cows fed WS was also correlated with the highest urinary N excretion (g/d), which was found for the cows fed that same diet (189 vs. 147 on average for the other diets). The protein digestibility was higher for the cows fed the CS and WS diets (on average 68.5%) than for the cows fed AS and PR (on average 57.0%); dietary soybean inclusion was higher for CS and WS than for AS and PR. The rumen fermentation pattern was affected by the diet; the cows fed the PR diet showed a higher rumen pH and decreased propionate production than those fed CS, due to the lower nonfiber carbohydrate content and higher ash-free neutral detergent fiber content of the PR diet than the CS diet. Feeding cows with PR diet increased the acetate:propionate ratio in comparison with the CS diet (3.30 vs. 2.44 for PR and CS, respectively). Cows fed the PR diet produced a greater daily amount of methane and had a greater methane energy loss (% of digestible energy intake) than those fed the CS diet (413 vs. 378 g/d and 8.67 vs. 7.70%), but no differences were observed when methane was expressed as grams per kilogram of DMI or grams per kilogram of milk. The PR diet resulted in a smaller net energy for lactation content than the CS diet (1.36 vs. 1.70 Mcal/kg of DM for the PR and CS diets, respectively). Overall, our research suggests that a satisfactory milk production can be attained by including different high-quality forages in balanced diets without any negative effect on milk production or on the methane emissions per kilogram of milk.

Cow faeces have been investigated as alternative inoculum to replace rumen fluid to determine neutral detergent fibre (NDF) digestibility (NDFD). Aims of this study were to estimate: (1) the NDFD (48 h) of feed ingredients using a rumen inoculum in comparison with faecal inocula from cows fed diets with different forage basis; (2) the undigestible NDF (uNDF) at 240 and 360 h with ruminal fluid and faecal inocula from lactating cows fed two different diets. At 48 h incubation, the NDFD was affected both by feed and type of inoculum (p < 0.01) and by their interaction (p = 0.03). Overall, the mean NDFD was higher for rumen inoculum than for faecal inocula (585 vs. 389 g/kg NDF, p < 0.05), and faecal inoculum obtained from cows fed hay-based diets gave lower NDFD than those from cows fed maize silage (367 vs. 440 g/kg, p < 0.05). At long incubation times, the average uNDF was affected by substrate, inoculum and incubation time (p < 0.01), but not by their interactions. For each inoculum, significantly lower values were obtained at 360 than at 240 h. Regressions between uNDF with rumen and with the tested faecal inocula resulted in r2 ≥ 0.98. Despite the differences at 48 h, the uNDF showed that faecal inoculum could replace rumen fluid at longer incubation times.