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Nitrogen balance (NB) experiments allow calculation of N retention in the body by subtracting N excreted in feces (NF), urine (NU) and milk (NM) from N intake (NI). In a previous study, we found that NB data from experiments with lactating dairy cows were generally high and, in the current meta-analysis, we update our earlier study with experiments from the last 2 decades and investigate probable causes of error. A total of 83 publications, with 86 experiments and 307 dietary treatments, were selected from top-ranked scientific journals that reported all NB components. The NB and NB components were analyzed by linear regression with a model that used NI as an independent variable and experiment as a random effect. The NF, NU and NM each represented 27 to 34% of NI, and the remaining N accumulated in the body was equal to 38.5 g/d (overall SD = 43.2 g/d). Retained N (as g/d or % of NI) increased linearly with NI, and this led to unlikely high N retentions, especially at high NI. Both NF and NU (g/d) increased with increasing NI, and we assume that some N in feces and urine were unaccounted. Only ~22% of experiments measured N in wet feces samples and, when analysis used dry samples, no mention of corrections due to potential volatile N losses during drying were reported. No experimentalists preserved feces immediately to prevent volatilization during collection. Moreover, ~27% of experiments estimated urine volumes by concentration of creatinine in spot samples, and in these experiments, NU was ~12% lower than those where total urine was collected (168 vs. 191 g/d). Only 40 experiments reported the volume and concentration of acids used for urine preservation, 33 furnished incomplete information, and the remainder did not describe the urine preservation method. In conclusion, the results of NB experiments using lactating dairy cows overestimate N retention, and the losses of N from feces and urine are the most probable reason. [ABSTRACT FROM AUTHOR]

The aim was to estimate the ME content of TMR samples for lactating dairy cows based on 24 h gas production (GP) measured in two TMR fractions obtained by sieving that were considered proxy representations of their forage and concentrate contents. Samples of TMR for lactating cows, collected at 15 Italian dairy farms, were dried and fractionated using an apparatus composed of four sieves (mesh diam. of 6.00, 2.36, 1.18, 0.60 mm) and a bottom pan. The particles retained by the 6.00, 2.36 and 1.18 mm sieves were bulked to create a fraction named “Long” (L), while particles retained by the 0.60 mm sieve and the bottom pan created a fraction named “Fine”(F). Samples of whole TMR and of F and L fractions were fermented in rumen fluid (220 mg of dried sample into graduated 100 ml glass syringes with 30 ml of diluted rumen fluid) to measure GP at 0, 1, 2, 4, 6, 8, 12, 24, 48 and 72 h of incubation, and GP at 24 h was used in multiple equations to predict the ME content. The L fraction was the main part of the TMR (633 ± 61.7 g/kg DM) and contained more aNDFom (391 vs 185 g/kg DM; P < 0.01), less starch (213 vs 394 g/kg DM; P < 0.01) and less CP (132 vs 181 g/kg DM; P < 0.01) than the F fraction. The 24 h GP measured on the F fraction was 17% higher (P < 0.01) than in the L fraction lending to a 25% increase in the predicted ME content of the F fraction (12.1 vs 9.7 MJ/kg DM, P < 0.01). When the GP of the two fractions were summed on the basis of their relative weights in each TMR to obtain a calculated GP of the whole TMR, this did not differ from that directly measured on the original TMR sample. The ME values of the TMR had substantial variability among samples and the highest ME values measured for the F and L fractions were 13.23 and 10.82 MJ/kg DM, respectively. The inclusion of these F and L fraction values in TMR samples that had the lowest ME concentrations (e.g. 10.0–10.4 MJ/kg DM), as an hypothetical consequence of an improvement in nutritive quality of the dietary feed components, resulted in a calculated ME increment of about 0.5–0.6 and 0.8–1.0 MJ/kg DM, respectively. These simulations suggest appreciable ME variations in cases of substituting nutritionally extreme forages and/or concentrates with corresponding feeds of different nutritive quality. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the chemical composition and rumen degradability of ensiled soybean forage harvested at three plant vegetative stages ( i.e. , R4, R5, R6) and wilted for 20 or 28 h. The wilted forages were chopped from 1 to 2 cm and then manually pressed into 6 kg bags of fresh material (two bags for each combination of maturity stage and wilting duration) prior to storage under anaerobic condition for 90 days. The soybean silages were analysed for fermentative parameters and manually separated into leaves, stalks and pods. Whole forage and separated plant components were chemically analysed and the in vitro neutral detergent fibre (NDF) ruminal degradation (NDFD) was determined. Only whole plant silages were assessed for in vitro gas production (GP) and in vitro crude protein degradability (CPD). The dry matter (DM) content of the ensiled whole plants increased (P=0.005) from 454 to 485 and 518 g/kg from the R4 to R5 and R6 vegetative stages and was higher for forages wilted at 28 h than those at 20 h (528 vs 444 g/kg, P<0.001). Advancing plant maturity increased (P<0.001) the crude protein (CP) and ether extract (EE) content from 164 to 199 and from 18 to 53 g/kg DM, respectively, but reduced ash (P=0.011) from 71 to 63 g/kg DM. The NDFD increased with plant maturity from 0.319 to 0.465 (P<0.001). The GP did not differ among maturity stages of forages or wilting lengths, while CPD increased from 0.391 to 0.548 (P<0.001) with advancing maturity and slightly decreased with the longer wilting duration (P<0.008). The DM content of the pods and stalks increased (P<0.01) with the vegetative stage and CP content increased in pods and decreased in leaves. Results indicate that harvesting soybean forage at an advanced maturity stage ( e.g. , from R4 to R6) greatly increases the protein, the fat and the degradable NDF contents. Moreover, the wilting soybean forage has to be targeted to achieve a DM content of ensiled forage of about 440 g/kg (between about 410 and 480 g/kg, according to the maturity stage), and a further wilting determines no fermentative improvements at ensiling or relevant modification of silage nutritional contents. [ABSTRACT FROM AUTHOR]

Abstract: This study determined impacts of a commercial blend of microencapsulated essential oils (EO), fed at increasing dose levels to high yielding primiparous dairy cows, on milk yield and composition. Eight pregnant Holstein heifers, selected to have their parturition within a period of 30d, were kept in tie stalls equipped for individual feeding, and with free access to water, from the 7th month of gestation. At an average of 40d postpartum, cows were assigned to one of four dietary EO levels in a replicated 4×4 Latin square design. The experimental diets (i.e., corn silage, fescue hay and a compound feed, 6.5, 4.4 and 8.7kg DM/d respectively) differed only in the addition level of a microencapsulated EO supplement (RumaXol Feed) mixed at different levels into the compound feed (fed at 1kg/cow day) in order to provide 0, 0.32, 0.64 and 0.96g/d of the EO mixture. The experiment had four experimental periods of 21d, with the last 5d used for collection of faeces and urine, for milk yield and composition recording and measurement of cow biometric data. The dietary EO supplementation had no effect on dry matter (DM) intake, water consumptions or faecal DM, while urine density was (P=0.01) lower at the intermediate EO dosages. Digestibility and biometric measures of cows were not modified by EO feeding. The protein content of milk tended (P=0.06) to be higher at the intermediate EO dosages, as did (P=0.05) the milk energy concentration. However milk and milk component yields were not affected by EO feeding level. [Copyright &y& Elsevier]

Abstract: This study determined the chemical composition and metabolizable energy (ME) value for ruminants of seeds and pulps from grape pomaces (GP), which were produced from white and red Vitis vinifera cultivars in Italy and California (USA). Six Italian (i.e., three white and three red) and five California red cultivars were collected after the crush of grape juice had been completed and were ensiled in micro-silos for 45d. Fresh and ensiled samples were manually sieved to separate seeds from the pulp plus skin fraction and an overall inventory of 44 samples was obtained from the 24 Italian and 20 California samples (i.e., seeds and pulp fractions, fresh or ensiled from 6 or 5 cultivars, respectively). Both in seeds and pulp, the red Italian samples had higher organic matter (P<0.01), ether extract (P<0.05), neutral detergent fiber (aNDF, P<0.01), acid detergent fiber (ADF, P<0.01), lignin(sa, P<0.01) and Cu (P=0.02 and P<0.01, respectively) relative to the California red samples. In addition, K (P<0.01), Fe (P<0.01) and Zn (P=0.03 and P<0.01, respectively in seeds and pulps) were higher in red samples from California versus those from Italy. Italian white samples had higher saponins in pulp (SAP, P<0.05) and tended to have higher total extractable phenolics both in seeds and pulps (P=0.07 and P=0.10, respectively) than did Italian reds. Both in seeds and pulps, ensiling increased concentrations of aNDF (P<0.01 and P=0.08, respectively), ADF (P<0.01) and lignin(sa) (P<0.01 and P=0.03, respectively), had no impact on mineral levels and decreased concentrations anthocyanins (P=0.05) and SAP (P=0.01), respectively in seeds and pulp. Samples were fermented in diluted rumen fluid to measure in vitro rumen fermentability in terms of gas production, which was used to predict ME. Gas production from seeds of different origin were similar, with the exception of higher values at 48h in red California cultivars with respect to those from Italy (19.2ml versus 18.0ml, P<0.05). In pulps, Italian reds did not differ from Italian whites, but had lower gas production than the red California samples (9.2ml versus 12.2ml, 16.6ml versus 21.3ml, 26.3 versus 32.7, P<0.01, at 4, 24 and 48h respectively). Ensiling reduced gas production in seeds at 24 and 48h of incubation (P<0.01) and in pulps at 48h (P=0.09). Seeds from Italian red samples were lower (P<0.01) in ME than Italian whites (6.23MJ/kg DM versus 6.89MJ/kg DM, P<0.01) and higher (P<0.01) than the California samples (5.58MJ/kg DM). There were no differences between ME of the groups of pulps, but ensiling reduced estimated ME content in seeds (5.94MJ/kg DM versus 6.54MJ/kg DM, P<0.01), but not in pulps. On the basis of our results, and in agreement with other recent papers and/or textbook data, the potential to use de-seeded GP as a feed in diets of high producing ruminants is limited. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate changes over time in chemical composition, digestibility and net energy for lactation (NEl) contents of 12 species of alpine pastures during the vegetative season (i.e., Agrostis tenuis, Anthoxanthum alpinum, Carex sempervirens, Festuca rubra, Nardus stricta, Phleum alpinum, Poa alpina, Poa violacea, Alchemilla vulgaris, Leontodon hispidus, Potentilla aurea, Trifolium repens). Wild seeds were collected from plants spontaneously occurring in mountain pastures in North-East Italy and sown in a greenhouse. Plants were transplanted in open main field plots. Each main plot was divided into sub-plots, which were cut (first cut) in succession every 10 days in two consecutive years. Herbage regrowth (second cut) was evaluated at 45, 60 and 75 days after first cut. Herbage samples were analysed for chemical composition, for in vitro organic matter digestibility (OMD), and the NEl content was estimated. During the pasture utilisation period (i.e., thermic sum between 500 and 1200°C) the species had limited variation in their average CP contents (81–109g/kgDM) excluding the lowest values of F. rubra and P. violacea (74 and 71g/kgDM, respectively; P<0.05) and the highest value of T. repens (202g/kg DM; P<0.05). Within grasses, there were very fibrous species (>700gNDF/kgDM, such as F. rubra, N. stricta and P. violacea) and species with medium contents (573–664gNDF/kgDM), while forbs and the legume specie had a low content (≤403gNDF/kgDM). The OMD ranged from P. violacea (256g/kgDM; P<0.05) to T. repens (730g/kgDM; P<0.05). The highest NEl content was for T. repens (6.3MJ/kgDM; P<0.05), while low NEl values were calculated for N. stricta and C. sempervirens (2.9 and 2.5MJ/kgDM, respectively). The lowest (P<0.05) NEl content was estimated for P. violacea (1.9MJ/kgDM). Most species investigated (in particular, Agrostis tenuis, F. rubra, L. hispidus, Potentilla aurea), had an initial intense decrease in the CP content with advancing season, reaching minimum levels at the thermic sum of 800–1000°C. During season advancement, all species had increased NDF content, with marked increments for F. rubra and Poa species, and all species had decreased NEl contents. Regrowth samples collected at 75 days after first cut had lower CP and NEl contents relative to those collected after 45 days from the first cut (140g/kg versus 160g/kgDM and 4.4MJ/kg versus 4.8MJ/kgDM, respectively; P<0.05). This study provides nutritional information on individual herbage species of alpine pastures at different vegetative phases which can be used to obtain average nutritional values of use in pasture management work. [Copyright &y& Elsevier]

Abstract: This study was designed to evaluate effects of increasing doses of a blend of essential oils (EO; oregano, cinnamon, thyme, orange peel) on in vitro rumen fermentation in rumen liquor from dairy cows and fattening bulls, as influenced by acidity at the start of the fermentation. Two in vitro fermentation experiments, which differed only in the origin of rumen liquor (i.e., dairy cows [DC] or fattening bulls [FB]), were conducted in duplicate runs in 100ml glass tubes containing 50ml of diluted rumen fluid and 500mg of a mixed ration substrate. The pH of the diluted rumen liquor at the beginning of each fermentation was adjusted to 7.0 with 5N NaOH or 5.5 with 3N HCl. The EO blend was added to each fermentation tube at doses of 8, 16, 24 and 32μl/tube, equivalent to 160, 320, 480 and 640μl/l, using 3 tubes for each dosage level plus 3 tubes without EO as controls (i.e., 30 tubes in total/run). After 24h of incubation, fermentation liquor was collected and analyzed for volatile fatty acids (VFA), ammonia N and pH. In both experiments, pH and ammonia N concentration of the fermentation liquor were lower (P<0.01) at the initial pH of 5.5. The reduction of initial pH from 7.0 to 5.5 depressed VFA yield (138mM versus 120mM and 132mM versus 111mM, P<0.01, respectively, for DC and FB rumen liquors), and modified end products of fermentation by lowering the acetate:propionate ratio (4.3 versus 3.6 and 3.2 versus 2.5, P<0.01, respectively, for DC and FB rumen liquors). Butyrate concentration was higher at the lower pH in the DC rumen liquor fermentation (22.4mM/100mM versus 16.2mM/100mM, P<0.01), but not in the FB fermentation. In both experiments, addition of the EO blend did not depress total VFA concentrations, except at the highest dose in the experiment with rumen fluid from DC (122mM versus 128mM, P<0.01). In both experiments, there was an interaction (P<0.01) between EO addition and initial pH on acetate proportion; at the initial pH of 5.5, EO addition decreased acetate from 65.0 to 63.9 and from 62.6 to 61.8mM/100mM, respectively, for DC and FB rumen liquors, while there were no effects of EO at the initial pH of 7.0. In the experiment with DC rumen liquid, EO addition tended (P<0.08) to increase propionate proportion (from 16.1 to 16.6mM/100mM), while there was no effect in FB rumen liquid. In the FB experiment, EO decreased (P<0.05) the acetate:propionate ratio, while in the DC experiment it decreased only at low pH (interaction ‘EO addition×initial pH’: P<0.01). A moderate shift in end products of fermentation occurred with both types of rumen liquor, but mainly at low ruminal pH (i.e., 5.5), suggesting a selective toxicity of these EO against rumen bacterial strains that grow at low rumen pH. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate changes over time in chemical composition, digestibility and net energy for lactation (NEl) contents of 12 species of alpine pastures during the vegetative season (i.e., Agrostis tenuis, Anthoxanthum alpinum, Carex sempervirens, Festuca rubra, Nardus stricta, Phleum alpinum, Poa alpina, Poa violacea, Alchemilla vulgaris, Leontodon hispidus, Potentilla aurea, Trifolium repens). Wild seeds were collected from plants spontaneously occurring in mountain pastures in North-East Italy and sown in a greenhouse. Plants were transplanted in open main field plots. Each main plot was divided into sub-plots, which were cut (first cut) in succession every 10 days in two consecutive years. Herbage regrowth (second cut) was evaluated at 45, 60 and 75 days after first cut. Herbage samples were analysed for chemical composition, for in vitro organic matter digestibility (OMD), and the NEl content was estimated. During the pasture utilisation period (i.e., thermic sum between 500 and 1200°C) the species had limited variation in their average CP contents (81–109g/kgDM) excluding the lowest values of F. rubra and P. violacea (74 and 71g/kgDM, respectively; P<0.05) and the highest value of T. repens (202g/kg DM; P<0.05). Within grasses, there were very fibrous species (>700gNDF/kgDM, such as F. rubra, N. stricta and P. violacea) and species with medium contents (573–664gNDF/kgDM), while forbs and the legume specie had a low content (≤403gNDF/kgDM). The OMD ranged from P. violacea (256g/kgDM; P<0.05) to T. repens (730g/kgDM; P<0.05). The highest NEl content was for T. repens (6.3MJ/kgDM; P<0.05), while low NEl values were calculated for N. stricta and C. sempervirens (2.9 and 2.5MJ/kgDM, respectively). The lowest (P<0.05) NEl content was estimated for P. violacea (1.9MJ/kgDM). Most species investigated (in particular, Agrostis tenuis, F. rubra, L. hispidus, Potentilla aurea), had an initial intense decrease in the CP content with advancing season, reaching minimum levels at the thermic sum of 800–1000°C. During season advancement, all species had increased NDF content, with marked increments for F. rubra and Poa species, and all species had decreased NEl contents. Regrowth samples collected at 75 days after first cut had lower CP and NEl contents relative to those collected after 45 days from the first cut (140g/kg versus 160g/kgDM and 4.4MJ/kg versus 4.8MJ/kgDM, respectively; P<0.05). This study provides nutritional information on individual herbage species of alpine pastures at different vegetative phases which can be used to obtain average nutritional values of use in pasture management work. [Copyright &y& Elsevier]

Anionic diets are fed to non-lactating pre-parturient cows to lower the dietary cation–anion difference index (DCAD), thereby limiting their risk of contracting milk fever, and other associated metabolic diseases, in early lactation. Data from 21 studies (86 dietary treatments) with dry dairy cows, published in referred scientific journals, were identified for meta-analysis to predict urinary and blood pH (pHu and pHb) change as a response to anionic diet feeding. All studies reported pHu, while only in 13 (46 treatments) was pHb measured. The pHu was predicted from three DCAD indexes, as calculated from three combinations of dietary ions (i.e. DCAD1: Na, K, Cl; DCAD2: Na, K, Cl, S; DCAD3: Ca, Mg, Na, K, Cl, S) and expressed as dietary concentration (mequiv./100 g DM). The best prediction of pHu, adjusted for the study effect, was obtained with the equation: pHu=5.868+0.0904DCAD1-0.0008DCAD12 (r2=0.86; S.E.=±0.373). Poorer predictions occurred with DCAD2 (r2=0.81; S.E.=±0.402) and DCAD3 (r2=0.73; S.E.=±0.481), while using daily equivalent intake did not improve the predictions. A smaller dataset of 46 dietary treatments was used to predict pHb on the basis of pHu. A linear regression (r2=0.76), after data correction for study effect, was obtained: pHb=7.26+0.020pHu. These equations predict the impact of DCAD on pHu and pHb allowing accurate anionic salt supplementations. [Copyright &y& Elsevier]

The NDF degradability (dNDF) of hays measured by an in situ method (nylon bag technique) was compared with in vitro fermentation, using the DaisyII incubator (Ankom®, Tech. Co., Fairport, NY, USA). Eighteen hays were produced from mountain areas (about 700 m.s.l.) from plots subjected to different cutting frequencies (two to four cuts per season) and types of N fertilisation (slurry and slurry plus mineral). Hay samples from each cut were incubated (in situ) in the rumens of three cows (incubation times: 2, 4, 8, 16, 24, 48 and 72 h; sample weight: 15 mg/cm2 of free bag area) or inserted (in vitro) into three different digestion jars (jar volume: 2 l; bag size 5 cm×3 cm; sample weight: 250 mg per bag) that were placed into the DaisyII incubator for 48 h.The forages showed large variation in effective dNDF (assumed rumen turn over rate: 3% per hour) which ranged from 38 to 43% for hays with two cuts to 58–65% for the hays with four cuts per season. The dNDF obtained in situ (Y, effective) and in vitro (X, after 48 h of incubation) were highly correlated (P<0.01) and the regression equation was Y=0.74(±0.05)X+6.39(±2.90), n=18, S.D.=±1.96, r2=0.94.The variability (coefficient of variation, CV) of the in vitro measurements (among jar repeatability) was 2.8%, which is close to that generally found for some chemical analyses of feedstuffs and lower than that obtained for the in situ measures (among cow repeatability, CV: 3.7%). The DaisyII incubator produces repeatable in vitro dNDF data which are highly related to those obtainable with the reference in situ procedure. [Copyright &y& Elsevier]

Effects of progressive supplementation of four different basal forage diets with a compound feed having a high negative cation/anion difference (about −750 meq./kg dry matter (DM)) on urinary pH and urinary mineral excretion was evaluated in dry cows. Four diets made up of 6 kg DM/day forage (Italian ryegrass (R), meadow hay (M), mixture of corn silage (C) and R or alfalfa (A) and R) and 3 kg DM/d of a compound feed, were offered in equal portions at 8.00 and 16.00 h to four dry, non-pregnant Friesian cows. Diets and cows were arranged in a 4×4 Latin Square design having experimental periods of 21 days. In each period, starting from the afternoon meal of day 11, the compound feed was gradually substituted in three 1 kg increments with the same compound feed supplemented with anionic salts. Interactions between type of forage and concentrate were significant for urinary pH values. Urine pH decreased at an increasing rate after anionic feed supplementation at different rates for the different of basal forage diets, with the lowest value for R and the highest for A diet. The 1 and 2 kg levels of substitutions elevated urinary Cl and urea concentrations, but not Na and K concentrations or urine volume: thus the osmolality increased from 266 to 334 mOsm/kg. The highest level of anionic feed supplementation (3 kg) sharply changed urine output patterns with increased urine volumes from 3.14 to 4.63 l/6 h and lowered urinary Cl and urea concentrations resulting in reduced urine osmolality from 334 to 277 mOsm/kg. The anionic compound feed caused a marked increase of the Ca concentration in urine, from 0.96 to 4.30 mmol/l, while P levels were not affected. Overall the anionic supplementation caused a progressive increase in urinary output of Cl and Ca (577–1085 and 2.50–15.53 mmol/6 h, respectively), while only the highest level of anionic compound feed resulted in significant increases in urea, Na and K outputs. Given the different effect of dietary forages on the pH decline of urine after anionic supplementation, the metabolic acidotic condition in close up dry cows should be monitored by the urinary pH to calibrate the dosage of anionic compound feed. [Copyright &y& Elsevier]

Study aims were to investigate associations of hyperketolactia (HYKL) status of Holstein dairy cows between 6 and 60 d in milk (DIM), defined by milk acetone (mACE) and β-hydroxybutyrate (mBHB) content, with daily milk yield and composition. Milk samples (∼5.0 million) were collected over a 5-yr period (2014–2019) within the milk recording system in Poland. Concentrations of mACE and mBHB determined by Fourier-transform infrared spectroscopy were used to categorize samples into 4 ketolactia groups. Based on threshold values of ≥0.15 mmol/L mACE and ≥0.10 mmol/L mBHB, ketolactia groups were normoketolactia (NKL; mACE <0.15 mmol/L and mBHB <0.10 mmol/L), BHB hyperketolactia (HYKL BHB ; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), ACE hyperketolactia (HYKL ACE ; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L), and ACE and BHB hyperketolactia (HYKL ACEBHB ; mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L). To investigate ketolactia association with production outcomes, a linear model was developed, including ketolactia group, DIM, parity, their interactions, year-season as fixed effects, and random effects of herd and cow. Among all milk samples, 31.2% were classified as HYKL, and of these, 52.6%, 39.6%, and 7.8% were HYKL ACEBHB , HYKL BHB , and HYKL ACE , respectively. Ketolactia groups differed for all traits studied in all parities and DIM. Among HYKL groups, lowest milk yield was found in HYKL ACEBHB cows, except for 6 to 30 DIM in first- and second-lactation cows. Milk yield of HYKL BHB cows was higher than that of NKL cows until 20 to 30 DIM, and then it was lower than NKL cows. Milk yield of HYKL ACE cows was mostly lower than NKL cows. Energy-corrected milk (ECM) yield of HYKL ACEBHB cows was higher than that of NKL cows until 30 to 35 DIM for second lactation and third lactation or greater, and in the whole study period for first lactation. The yield of ECM for HYKL BHB cows was mostly higher than that of NKL cows, whereas HYKL ACE cows had higher ECM than NKL cows until 15 to 25 DIM and then was lower for the HYKL ACE group. Milk composition differed among HYKL groups. Highest milk fat (MF) and lowest milk lactose (ML) contents were observed in HYKL ACEBHB cows. Cows in HYKL ACEBHB and HYKL BHB groups had higher MF and lower milk protein (MP; except in 6–8 DIM in first lactation) and ML content than NKL cows. Milk fat content was higher in HYKL ACE than NKL cows in first lactation and during the first 30 to 40 DIM in older cows. Lactose content was lower in HYKL ACE than in NKL cows within 30 to 40 DIM; afterward it was higher in NKL cows. Lower MP content was found in HYKL ACE than in NKL cows, except during 6 to 9 DIM for cows in first lactation and third lactation or greater. In conclusion, HYKL is associated with altered milk production in all parities, but a range of these negative relations depends on ketone status addressing both ACE and BHB contents. Further research is needed to ascertain underpinning biochemical defects of HYKL from elevated ACE, alone or in combination with BHB, during early lactation. [ABSTRACT FROM AUTHOR]

The capability of maintaining protozoa populations and reduce the accumulation of undigested material was investigated in two experiments using a stratified continuous-culture rumen fermenter (CCF) at various setting. The CCF consists of 8 × 2 L glass bottles, warmed at 39 °C and placed on a waterproof magnetic stirrer. Bottles are closed with a rubber stopper, with an insert for the inflow of artificial saliva and have the outflow at the base. In Experiment 1 the effect of two stirring frequencies (continuous vs intermittent, S1 and S2) and two dilution rates ( D , 1.29 vs 1.04) on the pH values and on the counts of the protozoa in the fermentation fluid was evaluated. The pH reached a steady state after 4 d of fermentation and S1 bottles had lower pH than those S2 (6.50 vs 6.57, P<0.001). The protozoa in the fermentation fluid (2.92 × 10 5 /ml at the beginning) declined sharply in the first 2 d of fermentation and stabilized at about 13 × 10 3 /ml in the S2 flasks, while the S1 flasks had lower protozoa concentrations (about 0.8 × 10 3 /ml, P<0.001). The D had no effects on pH and protozoa. Experiment 2 aimed to test effects of varying the daily diet ( F ) amount (15, 20, 25, 30 g DM/d of a diet with 50:50 forage: concentrate ratio) on the organic matter (OM) digestibility (OMD) and on the fermentative patterns. In two fermentation runs of 8 d each, bottles were inoculated with 450 ml of rumen fluid and 1050 ml of artificial saliva, which was then pumped at a rate of 78 ml/h. Lowering F reduced the OM accumulated inside the vessels (from 5.06 to 0.68 g/d; P<0.001) but did not affected the OMD for any of the dietary treatments (range between 0.460 and 0.510). The reduction of F led to a linear decrease (P<0.001) in volatile fatty acids concentration (from 65.8 to 45.3 mM) and to an increase of acetate:propionate ratio (from 2.91 to 3.42) and of pH (from 6.0–6.1 to 6.4–6.5). Lowering F tended to increase the number of protozoa (from 72 to 198 × 10 3 /ml, P=0.082). The tested CCF reaches stable conditions of fermentation after some days of adaptation, allows the survival of protozoa population and has a limited accumulation of undigested materials in the glass bottles. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the volatile compounds, physicochemical characteristics, and sensory properties of Montasio, a semicooked pressed cheese, produced from the milk of the dual-purpose Italian Simmental cows grazing on alpine pastures. A total of 72 cows grazing on 2 pastures, which differed in botanical composition (nutrient-rich pasture vs. nutrient-poor pasture), received 2 different levels of supplementation (3.0 vs 1.5 kg/head per day). The experimental cheeses were produced from whole, raw milk and ripened for 60 d. Sixty-one volatile compounds, including alcohols (11), aldehydes (6), ketones (10), lactones (2), esters (6), hydrocarbons (3), carboxylic acids (6), phenolic compounds (4), monoterpenes (7), sesquiterpenes (1), sulfur compounds (4), and amines (1), were detected. The main families in terms of relative weight appeared to be carboxylic acids, esters, and alcohols. A panel of trained assessors described the experimental cheeses as having an intense color; small and evenly distributed eyes; an intense odor and flavor of milk-sour, milk, and cow; and a tender and creamy texture. The pasture type affected the volatile fraction, particularly ketones, phenolic compounds, and terpenes, which are overall higher in nutrient-poor pastures. A slight effect on the sensory analyses, in particular the effect of the cow attribute on odor and flavor, was perceived by the panelists. The cheeses produced on nutrient-rich pasture had higher b* (yellowness) index. These results were consistent with the color evaluation of the sensory panel. In addition, the pasture affected some textural attributes (adhesivity, creaminess, and granules) as perceived by the panelists. Concentrate supplementation, which is required to meet the feeding requirements of grazing cows, had no clear effect on either the volatile compounds or the sensory properties of the cheeses. Thus, at least within levels of integration adopted, it is expected not to alter the organoleptic characteristics of this product. [ABSTRACT FROM AUTHOR]

The aim of the trial was to compare two dietary levels of whole ear corn silage (ES), fed in two physical forms (coarse or after wet milling), on growth, slaughter traits and stomach development of heavy finishing pigs. Fifty six “Italian Large White × Italian Duroc” (about 5 months of age and 78–80 kg of live weight (LW) were divided into pairs homogeneous and were kept in 28 pens (1.2 × 3 m, partially-slatted) equipped with two separate troughs to avoid competitions for feeding and with free access to water. Four dietary treatments resulted from the combination of two ES inclusion levels (300 and 400 g/kg dry matter (DM), ES30 and ES40, respectively) and two physical forms of the silage (coarse and wet milled). Seven pairs of pigs were randomly assigned to each dietary treatment and the animals were slaughtered at an average LW of 163.0 kg (±1.9 kg). The coarse ES had particles longer than the milled silage (4.4 vs 2.7 mm) and when it was fed to pigs the pH of fecal samples were lower (P<0.01) than that from pigs fed the milled ES, at both dietary inclusion levels (6.00 vs 6.20 for the ES30 diets and 5.97 vs 6.14 for the ES40 diets). There were no significant differences in organic matter total tract digestibility, average daily gain, DM intake and gain:feed ratio among the dietary treatments (0.81, 764 g/d, 77.1 g DM/kg LW 0.75 , 0.266 g/g DM, on average, respectively). The ES40 diets reduced the Longissimus dorsi thickness (56.4–59.8 vs 62.7–64.1 mm, P<0.011) and increased the stomach weight (0.0040 vs 0.0038 of the LW, P<0.05), while the coarse dimension of silage particles increased the DM content of the material in the stomach (from 142–171 to 179–183 g/kg DM, P<0.045) and the surface of the pyloric region (from 214–216 to 225–232 cm 2 , P<0.029). The two dietary inclusion levels and physical forms of ES do not differentiate growth and slaughter traits of the heavy finishing pigs. However, the coarse form of the silage modifies the development of the stomach by increasing the internal surface of the pyloric region as a possible consequence of a longer retention time in the stomach. [ABSTRACT FROM AUTHOR]

Abstract: The experiment compared reductions in the level of N fertilisation of corn crop (i.e., no N fertilisation; 0-N, or 150kg of N/ha; 150-N) with those currently adopted in the Po valley of North Italy (i.e., 300kg of N/ha; 300-N) on chemical and nutritional characteristics of grain, stalks and leaves in corn hybrids selected for whole plant silage production (i.e., FAO 700 maturity). Grain composition and starch availability for digestion was examined at three stages of maturity of the kernels (i.e., ½ milk line, ¾ milk line and black layer). One hybrid had a lower grain yield (15.2 versus 16.0–16.8tonnesDM/ha; P<0.05), while all hybrids were similar in whole plant yield. Levels of N fertilization of 150-N and 300-N resulted in similar yields of grain and whole plants, which were 17 and 33% higher, respectively (P<0.01) than 0-N plots. Hybrids were similar in chemical composition. Reduction of N fertilisation from 300-N to 0-N lowered (P<0.01) the crude protein content in grains, leaves and stalks (P<0.05 in apical part of stalks) and reduced the zein content in grains from 43 to 33g/kg DM (P<0.01). Vitreousness of grains was not influenced by N fertilisation, while the highest (P<0.01) gas production was at the short incubation time of 2h for grains with 300-N. Reduction of fertilisation levels (i.e., 150-N and 0-N versus 300-N) lowered (P<0.01) NDF degradation in the basal stalks (0.385 and 0.392 versus 0.412) and leaves (0.604 and 0.620 versus 0.622). Stage of maturity of grain did not interact with the N level of fertilization, and advanced maturity was associated with a marked increase (P<0.01) in zein content from 36 to 49g/100g CP and in grain vitreousness from 31 to 40g/100g endosperm and with a reduction of the gas production, which had the lowest values at 2 and 48h (P<0.01) of incubation. Overall, reductions in N fertilisation of corn crop slightly lowered the crude protein content and fiber degradation of different part plants. In grains, the lowest N fertilisation (i.e., 0-N) reduced the zein contents and increased rumen fermentability. [Copyright &y& Elsevier]

Abstract: This experiment determined the chemical composition, rumen degradability (aNDF in stalks and starch in kernels) and in vitro gas production of kernels from three corn hybrids treated (TT) or not treated (control, CTR) with insecticides against the European corn borer (ECB, Ostrinia nubilalis). Two whole-plant silage hybrids belonging to the FAO rating 600 and 700 maturity class (S600 and S700, respectively) and one selected for grain production (G600, FAO rating 600, Dekalb-Monsanto Agricoltura S.p.A., Lodi, Italy) were sown in two main plots (TT and CTR) of an experimental field. Two subsequent treatments of pyrethroids (25 and 1.2g/ha of cyfluthrin and deltamethrin, respectively) were applied to the TT plots. The insecticide treatment reduced the number of damaged plants (4.5 broken plants/plot versus 0.3 broken plants/plot, P<0.01) and increased the total grain yield by 11% (13.8t/ha versus 12.4t/ha), while hybrids did not differ. ECB larvae which bored into the stalk tunnels modified the chemical composition of stalks and kernels. In stalks, total sugars content (i.e. glucose, fructose, sucrose) was about twice that in TT versus CTR plants (123g/kg versus 60g/kg DM, P<0.01), while aNDF content was higher in CTR stalks (765 versus 702g/kg DM, P<0.01). DM degradability after 48h of incubation of stalks was higher in TT than in CTR, both in vitro (0.360 versus 0.298, P<0.01) and in situ (0.370 versus 0.298, P<0.05), while there were no differences in aNDF degradability. Kernels from TT plots contained less DM (615g/kg versus 651g/kg, P<0.01) and more CP (84g/kg and 78g/kg DM, P<0.05) than those from CTR plots, while in situ rumen starch disappearance and in vitro gas production were similar. Corn hybrid selected for yield of grain (G600) differed from S600 and S700 due to a higher (P<0.01) content of aNDF, ADF and lignin(sa) in the stalks, and a higher starch content (696g/kg versus 674 and 671g/kg DM, P<0.01) and CP (87g/kg versus 77 and 76g/kg DM, P<0.05) in grain. The G600 hybrid produced stalks with a lower (P<0.01) aNDF rumen degradability than the S600 and S700. On field ECB insecticide treatment improved corn grain yield, reduced broken plants and increased stalk sugars content at harvesting, but did not change the rumen degradation of either stalks or grain. [Copyright &y& Elsevier]

Intra- and inter-laboratory variation of in vitro gas production and calculated metabolizable energy (ME, MJ/kg DM) values were studied using 16 test feeds in 7 laboratories. Intra-laboratory variation was low, with six of the seven laboratories having very high relationships in gas production between runs (R2≥0.96) and slopes that did not differ from unity. Inter-laboratory differences were higher with highly significant (P<0.001) differences among laboratories in both gas production and calculated ME values. Three of the six test laboratories generated predicted ME values that did not differ from the seventh (reference) laboratory. Combining intra-laboratory variation in gas production and inter-laboratory variation in predicted ME values, three of the six test laboratories were judged acceptable overall. ME values predicted by the gas production technique by laboratories in different parts of the world cannot be considered absolute. [Copyright &y& Elsevier]