Analyses of consumers' preferences and of the correspondence between direct and indirect label claims and the fatty acid profile of milk in large retail chains in northern Italy.

Combined results from 2 survey studies were used to obtain information useful for the industries and retailers involved in the milk production and selling chain in North Italy. The first survey identified different clusters of fluid milk purchasers by examining their preferences and attitudes toward 12 intrinsic-extrinsic and credence milk attributes, by applying best-worst scaling methodology, whereas the second survey characterized the fatty acid (FA) profiles of commercial milk sold by large-scale retailers to verify the correspondence between the actual FA profile and the direct and indirect claims on the labels. To summarize information about the FA profile of milk, which may be considered an advanced attribute of milk quality, the milk FA index (MFAI) was calculated for each milk sample. A total of 130 milk samples (around 85% of the labels in northern Italy) and a total of 502 participants who answered a face-to-face questionnaire were considered in the 2 surveys. The milk samples were 13.1% organic, 9.2% certified as being of mountain origin, and over 50% noncertified but linked to cow grazing or to a mountain environment on their labels. The FA profiles showed a wide range of variation, with saturated FA ranging from 63.4 to 71.8, and polyunsaturated FA from 2.76 to 5.85. The FA profile and MFAI index of certified milk (organic or mountain-derived) were significantly different from the profiles of noncertified milk, whereas no correspondence was observed between the retail price and milk quality. When ranked on the basis of MFAI, which proved to be a good discriminating tool, the certified milks presented a bimodal distribution, indicating that certification does not always guarantee a real difference. The consumers chose milk considering the origin of the product, brand, expiration date, and process certification as the most important attributes, whereas they rated price and organic certification as the least important attributes. The study showed that about 20% of the consumers had a high propensity to buy milk on the basis of its quality. However, this attribute is often incorrectly indicated or not indicated at all on the milk label, with misleading images or claims that do not correspond to the actual FA quality of the milk. Having a clear index that offers information about the FA profile could thus be an interesting tool to improve the awareness of buyers and to valorize and differentiate milk products.

Feed-out rate used as a tool to manage the aerobic deterioration of corn silages in tropical and temperate climates.

There is an increasing recognition throughout the world that many of the feeding problems of dairy herds are linked to the presence of aerobically deteriorated parts on a silo face, causing farmers to pose questions on what amount of silage should be removed daily to feed their animals. Since an adequate feed-out rate helps to prevent silage spoilage, a simple tool is needed to manage the aerobic deterioration of corn silages during feed-out. The aims of this study were to develop an unloading rate index, which we have called the mass feed-out rate (MFR), expressed in kilograms of fresh matter silage unloaded daily per square meter of silo face, to better predict the aerobic deterioration of silage and to offer management solutions to help prevent spoilage, through a survey on 97 commercial dairy farms in Italy and Brazil. Silages were sampled and analyzed for their main microbial, fermentative, and nutritional characteristics, whereas silage temperatures were measured in the core and peripheral areas of the silo working face. Moreover, a detailed questionnaire on silo management and silage utilization was administered to the farmers during each farm visit. The size and silage density of the silos presented a wide variability in the 2 countries, thus indicating that different management practices were adopted during corn harvesting, silo filling, and silage compaction. The differences between pH and temperature in the peripheral areas and in the core of the silage (dpH and dT, respectively) were tested as a single indicator to identify any aerobic deteriorated areas on the silo face, associated with the yeast and mold counts. Both indicators correctly identified aerobic deterioration in 86.6% and 93.8% of the studied silos, respectively. The lactic acid and ethanol increased as the MFR increased, whereas the starch, dT, and the yeast and mold counts decreased with increasing MFR. A daily removal rate of over 250 kg of silage/m2 markedly reduced the risk of spoilage in corn silages at a farm level in both temperate and tropical environments. The new MFR index can substitute for the commonly used linear feed-out rate as it includes the silage density and can be obtained from 1 single recording.

Milk production, methane emissions, nitrogen, and energy balance of cows fed diets based on different forage systems.

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.

Dairy farm management practices and the risk of contamination of tank milk from Clostridium spp. and Paenibacillus spp. spores in silage, total mixed ration, dairy cow feces, and raw milk.

The occurrence of Paenibacillus and Clostridium spores in silage is of great concern for dairy producers because their spores can contaminate milk and damage processed milk and semi-hard cheeses. Spoiled silage is considered to be the main contamination source of the total mixed ration (TMR), feces of dairy cows, and consequently bulk tank milk via the contamination of cow teats by dirt during milking. The presence of an anaerobic and facultative anaerobic sporeformer population in different matrices (soil, corn silage, other feeds, TMR, feces, and milk) and its transmission pathway has been studied on 49 dairy farms by coupling plate count data with 16S-DNA identification. The different matrices have shown a high variability in the anaerobic and facultative anaerobic spore count, with the highest values being found in the aerobically deteriorated areas of corn silages. Clostridium tyrobutyricum, Paenibacillus macerans, and Paenibacillus thermophilus were detected in all the matrices. The TMR spore count was influenced by the amount of spoiled corn silage in the TMR and by the care taken when cleaning the spoiled silage before feed-out. Most of the farms that prevent the presence of visible moldy silage in the silo and carefully clean to remove molded spots were able to maintain their TMR spore counts below 4.0 log spores/g. When a level of 4.5 log spores/g of TMR was exceeded, the feces presented a greater contamination than 3.0 log spores/g. Moreover, the higher the number of spores in the feces was, the higher the number of spores in the milk. Most of the farms that presented a feces contamination greater than 5.0 log spores/g had a higher milk spore contamination than 1,000 spores/L. Careful animal cleaning and good milking practices have been found to be essential to maintain low levels of contamination in bulk tank milk, but it has emerged that only by coupling these practices with a correct silage management and cleaning during TMR preparation can the contamination of milk by spores be kept at a low level. It has been found that aerobically deteriorated silage has a great capacity to contaminate TMR and consequently to increase the risk of milk spore contamination, even when routine milking practices are adopted correctly.

Silage review: Factors affecting dry matter and quality losses in silages.

An overview was made of dry matter (DM) and quality losses that occur during the ensiling process from the field through the feeding phase. The aim was to review the relevant published literature of the last 15 yr focusing on developments achieved after the publication of the book Silage Science and Technology. This review discusses the factors affecting DM and quality losses in terms of field and pre-ensiling conditions, respiration and temperature at ensiling, fermentation patterns, methods of covering and weighting the silage cover, and management of aerobic deterioration. The possibility of reducing DM and quality losses during the ensiling process requires knowledge of how to measure losses on farm and establish the status of the silage during the feed-out phase, implementing the most effective management practices to avoid air exposure during conservation and reduce silage aerobic deterioration during feeding. The paper concludes with future perspectives and recommended management practices to reduce losses and increase efficiency over the whole ensiling process in view of increasing sustainability of the livestock production chain.

Could predicting fatty acid profile by mid-infrared reflectance spectroscopy be used as a method to increase the value added by milk production chains?

The aims of this work were (1) to develop prediction equations from mid-infrared spectroscopy (MIRS) to establish a detailed fatty acid (FA) composition of milk; (2) to propose a milk FA index, utilizing MIRS-developed equations, in which the precision of the FA-prediction equations is taken into account to increase the value of milk; and (3) to show application examples. A total of 651 bulk cow milk samples were collected from 245 commercial farms in northwest Italy. The results of the 651 gas chromatography analyses were used to establish (421 samples) and to validate (230 samples) the outcomes of the FA composition prediction that had been obtained by MIRS. A class-based approach, in which the obtained MIRS equations were used, was proposed to define a milk classification. The method provides a numerical index [milk FA index (MFAI)] that allows a premium price to be quantified to increase the value of a favorable FA profile of milk. Ten FA were selected to calculate MFAI, according to their relevance for human health and potential cheese sensory properties, and animal welfare and environmental sustainability were also considered. These factors were selected as dimensions of MFAI. A statistical analysis and expert judgment aggregation were performed on the selected FA by weighting the FA and normalizing the dimensions to reduce redundancy. A class approach was applied, using the precision of the MIRS equations to establish the classes. The median FA concentration of the data set was set as a reference value of class 0. The width, number, and limits of classes above and below the median were calculated using the 95% confidence level of the standard error of prediction, corrected with the bias of each FA. A progressive number and a positive or negative sign were assigned to each FA class above or below the median according to their role in the above mentioned dimensions. The sum of the numbers of each class, associated with its sign for each FA, was used to generate MFAI. The MFAI was applied to dairy farms characterized by different feeding strategies, all of which deliver milk to a commercial dairy plant. The MFAI values ranged from 0.7 to 4.2, and large variations, which depended on the cows' diet and forage quality, were observed for each feeding system. The proposed method has been found to be flexible and adaptable to several contexts on both intensive and extensive dairy farms.

Detection, identification, and typing of Listeria species from baled silages fed to dairy cows.

Anaerobiosis, critical for successful ensilage, constitutes a challenge in baled silages. The loss of complete anaerobiosis causes aerobic deterioration and silages undergo dry matter and nutrient losses, pathogen growth, and mycotoxin production. Silage may represent an ideal substrate for Listeria monocytogenes, a pathogen of primary concern in several cheeses. The aim of this research was to investigate the occurrence of Listeria in baled silage fed to cows producing milk for a protected designation of origin cheese, and to characterize isolates by repetitive sequence-based PCR. Listeria spp. were detected in 21 silages and L. monocytogenes in 6 out of 80 of the analyzed silages; 67% of positives were found in molded zones. Results of the PCR typing showed genotypic homogeneity: 72.9 and 78.8% similarity between strains of Listeria spp. (n=56) and L. monocytogenes (n=24), respectively. Identical profiles were recovered in molded and nonmolded areas, indicating that contamination may have occurred during production. The application of PCR allowed the unambiguous identification of Listeria isolated from baled silages, and repetitive sequence-based PCR allowed a rapid and effective typing of isolates. Results disclose the potential of the systematic typing of Listeria in primary production, which is needed for the understanding of its transmission pathways.

Evolution of fungal populations in corn silage conserved under polyethylene or biodegradable films.

AIMS: To identify cultivable filamentous fungi before ensiling, after silage conservation, in farm-silos covered with two different plastic films (polyethylene (PE) vs biodegradable (MB)), as well as after aerobic exposure of whole-crop corn silage. METHODS AND RESULTS: Molecular techniques coupled with traditional microbial counting were utilized to identify the predominant fungal species. The cultivable fungal population changed remarkably from harvesting to silo opening. Anaerobiosis and low pH reduced mould count and the presence of Fusarium species both under PE and MB film. However, in the peripheral areas of the silo, where air penetration could not be completely prevented, the fungal population did not decrease. The predominant fungal species after aerobic exposure of silage was Aspergillus fumigatus, without differences between the two plastic films. CONCLUSIONS: Maintenance of anaerobiosis and a low pH also in the upper layer of the silo reduce the risk of mould growth during corn silage feed-out. SIGNIFICANCE AND IMPACT OF THE STUDY: Even if the new MB plastic film did not completely maintain the anaerobiosis in the upper layer of silage, the overall silage quality was not compromised and was similar to that observed under PE, indicating that the development and use of MB film to cover silage is promising, but needs some improvement.

Potential of milk fatty acid composition to predict diet composition and authenticate feeding systems and altitude origin of European bulk milk.

The aims of this work were to elucidate the potential of using milk fatty acid (FA) concentration to predict cow diet composition and altitude of bulk milk collected in 10 different European countries and to authenticate cow-feeding systems and altitude of the production area using a data set of 1,248 bulk cow milk samples and associated farm records. The predictions based on FA for cow diet composition were excellent for the proportions of fresh herbage [coefficient of determination (R2)=0.81], good for hay, total herbage-derived forages, and total preserved forages (R2>0.73), intermediate for corn silage and grass silage (R2>0.62), and poor for concentrates (R2<0.51) in the cow diet. Milk samples were assigned to groups according to feeding system, level of concentrate supplementation, and altitude origin. Milk FA composition successfully authenticated cow-feeding systems dominated by a main forage (>93% of samples correctly classified), but the presence of mixed diets reduced the discrimination. Altitude prediction reliability was intermediate (R2<0.62). Milk FA composition was not able to authenticate concentrate supplementation level in the diet (<58% of samples correctly classified). Similarly, the altitude origin was not successfully authenticated by milk FA composition (<76% of samples correctly classified). The potential of milk FA composition to authenticate cow feeding was confirmed using a data set representative of the diversity of European production conditions.

Improving corn silage quality in the top layer of farm bunker silos through the use of a next-generation barrier film with high impermeability to oxygen.

This study examined the effect on the fermentation, chemical, and microbiological quality of corn silage covered with a new-generation high oxygen barrier film (HOB) made with a special grade of ethylene-vinyl alcohol (EVOH) compared with a standard polyethylene film (PE). Two bunkers (farms 1 and 2) were divided into 2 parts lengthwise so that half of the silo would be covered with PE film and the other with HOB film. Plastic net bags with fresh chopped corn were buried in the upper layer (close to and far from the wall) and in the central part of the bunkers. During spring-summer consumption, the bags were unloaded, weighed, and subsampled to analyze the dry matter (DM) content, neutral detergent fiber and starch contents, pH, lactic and monocarboxylic acids, yeast and mold counts, aerobic and anaerobic spore-former counts, and aerobic stability. We also determined the economic benefit of applying the novel covering. The top layer of silage conserved under the HOB film had a higher lactic acid content and lower pH; lower counts of yeasts, molds, and aerobic and anaerobic spore-formers; higher aerobic stability; and lower DM losses than the silage conserved under the PE film. The use of the HOB film prevented almost all of the silage in the upper layer from spoiling; only 2 out of 32 samples had a mold count >6log10 cfu/g. This led to a net economic gain when the HOB film was used on both farms due to the increased DM recovery and reduced labor time required to clean the upper layer, even though the HOB film cost about 2.3 times more than the PE film. Furthermore, use of the HOB film, which ensures a longer shelf life of silage during consumption, reduced the detrimental effect of yeasts, molds, and aerobic and anaerobic spore-formers on the nutritional and microbiological quality of the unloaded silage.

Effect of different feeding strategies in intensive dairy farming systems on milk fatty acid profiles, and implications on feeding costs in Italy.

The aim of this work was to characterize the fatty acid (FA) profile of milk from intensive dairy farming systems in the Po Plain (Italy) to estimate the costs of the adopted feeding strategies and to simulate the effect of supplementary premiums on the basis of milk FA composition on milk income. Twenty dairy farms with 5 different feeding strategies were studied: 3 corn silage-based systems in which cows were supplemented with a great proportion (CCH), a medium proportion (CCM), or without commercial concentrate mix (CC0), and 2 systems in which part of corn silage was replaced with grass or legume silage (HF) or with fresh herbage (G), cut and fed indoors. Bulk milk was sampled and lactating cow performance, feeding strategies and forage characteristics were recorded through a survey, 3 times during a year. The milk FA supplementary premium was calculated considering C18:3n-3 and saturated FA (SFA) concentrations, and ratio of total cis C18:1 isomers to C16:0. The CCH, CCM, and CC0 systems bought most of their dairy cow feeds off farm, which allowed them to increase milk production to 35,000 L/yr per hectare. Their low dry matter and crude protein self-sufficiency led to higher feeding costs per liter of milk (from €0.158 to €0.184), and highest income over feed cost was achieved only for milk yield performance greater than 10,000 kg/cow per year. The use of homegrown forages in HF and G increased dry matter and crude protein self-sufficiency and reduced the feeding costs per liter of milk from 9 to 22%, compared with the other studied systems, making HF and G feeding economically competitive, even for a lower milk yield per cow. The studied systems highlighted a remarkable variation in FA profiles. The concentrations of C16:0 and SFA were the highest in CCH (31.53 and 67.84 g/100g of FA) and G (31.23 and 68.45 g/100g of FA), because of the larger proportion of commercial concentrate mix in the cow diet. The concentrations of C16:0 and SFA were the lowest in CCM (27.86 and 63.10 g/100g of FA), because of low roughage-to-concentrate ratio in the cow diet, which is known to favor milk fat depression, affecting particularly these FA. The calculated supplementary premium was the highest in the CCM system, based on milk FA profiles from those herds. The HF diet was rich in forages and resulted in greater concentration of C18:3n-3 in milk (0.57 g/100g of FA) than the other systems and thus led to an increase in milk FA supplementary premium. Milk from G and HF milk had the lowest ratio of Σn-6:Σn-3 FA compared with milk from the systems based on higher corn silage proportion in the cow diet (3.71, and 3.25, respectively, vs. 4.58 to 4.78), with the lower ratios being closer to recommendation for human nutrition.

Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys.

The aim of this study was to predict the fatty acid (FA) composition of bulk milk using data describing farming practices collected via on-farm surveys. The FA composition of 1,248 bulk cow milk samples and the related farming practices were collected from 20 experiments led in 10 different European countries at 44°N to 60°N latitude and sea level to 2,000 m altitude. Farming practice-based FA predictions [coefficient of determination (R(2)) >0.50] were good for C16:0, C17:0, saturated FA, polyunsaturated FA, and odd-chain FA, and very good (R(2) ≥0.60) for trans-11 C18:1, trans-10 + trans-11 C18:1, cis-9,trans-11 conjugated linoleic acid, total trans FA, C18:3n-3, n-6:n-3 ratio, and branched-chain FA. Fatty acids were predicted by cow diet composition and by the altitude at which milk was produced, whereas animal-related factors (i.e., lactation stage, breed, milk yield, and proportion of primiparous cows in the herd) were not significant in any of the models. Proportion of fresh herbage in the cow diet was the main predictor, with the highest effect in almost all FA models. However, models built solely on conserved forage-derived samples gave good predictions for odd-chain FA, branched-chain FA, trans-10 C18:1 and C18:3n-3 (R(2) ≥0.46, 0.54, 0.52, and 0.70, respectively). These prediction models could offer farmers a valuable tool to help improve the nutritional quality of the milk they produce.

Dry matter and nutritional losses during aerobic deterioration of corn and sorghum silages as influenced by different lactic acid bacteria inocula.

The economic damage that results from aerobic deterioration of silage is a significant problem for farm profitability and feed quality. This paper quantifies the dry matter (DM) and nutritional losses that occur during the exposure of corn and sorghum silages to air over 14 d and assesses the possibility of enhancing the aerobic stability of silages through inoculation with lactic acid bacteria (LAB). The trial was carried out in Northern Italy on corn (50% milk line) and grain sorghum (early dough stage) silages. The crops were ensiled in 30-L jars, without a LAB inoculant (C), with a Lactobacillus plantarum inoculum (LP), and with a Lactobacillus buchneri inoculum (LB; theoretical rate of 1 × 10(6) cfu/g of fresh forage). The pre-ensiled material, the silage at silo opening, and the aerobically exposed silage were analyzed for DM content, fermentative profiles, yeast and mold count, starch, crude protein, ash, fiber components, 24-h and 48-h DM digestibility and neutral detergent fiber (NDF) degradability. The yield and nutrient analysis data of the corn and sorghum silages were used as input for Milk2006 to estimate the total digestible nutrients, net energy of lactation, and milk production per Mg of DM. The DM fermentation and respiration losses were also calculated. The inocula influenced the in vitro NDF digestibility at 24h, the net energy for lactation (NE(L)), and the predicted milk yield per megagram of DM, whereas the length of time of air exposure influenced DM digestibility at 24 and 48 h, the NE(L), and the predicted milk yield per megagram of DM in the corn silages. The inocula only influenced the milk yield per megagram of DM and the air exposure affected the DM digestibility at 24h, the NE(L), and the milk yield per megagram of DM in the sorghum silages. The milk yield, after 14 d of air exposure, decreased to 1,442, 1,418, and 1,277 kg/Mg of DM for C, LB, and LP corn silages, respectively, compared with an average value of 1,568 kg of silage at opening. In the sorghum silages, the milk yield, after 14 d of air exposure, decreased to 1,226, 1,278, and 1,250 kg/Mg of DM for C, LB, and LP, respectively. When the estimated milk yield per megagram of harvested DM of corn and sorghum silage were related to mold count, it was shown that the loss of potential milk production occurred when the mold count exceeded 4 log cfu/g of silage, and it was almost halved when the mold count reached values greater than 8 log cfu/g of silage. Inoculation with L. buchneri, at a rate of 1 × 10(6) cfu/g of fresh forage, enhanced the stability of the silage after exposure to air, and, consequently, contributed to maintaining the nutritional value of the harvested forage over time, for air exposure up to 7 d.

Effect of Lactobacillus buchneri LN4637 and Lactobacillus buchneri LN40177 on the aerobic stability, fermentation products, and microbial populations of corn silage under farm conditions.

This study determined the efficacy of the use of 2 commercial inoculants containing Lactobacillus buchneri alone or in combination with homofermentative lactic acid bacteria in improving aerobic stability of corn silage stored in commercial farm silos in northern Italy. In the first survey, samples were collected from 10 farms that did not inoculate their silages and from 10 farms that applied a Pioneer 11A44 inoculant (L. buchneri strain LN4637; Pioneer Hi-Bred International, Des Moines, IA). In the second survey, corn silage samples were collected from 11 farms that did not inoculate their silages and from 11 farms that applied a Pioneer 11CFT inoculant (L. buchneri strain LN40177; Pioneer Hi-Bred International). Inoculants were applied directly through self-propelled forage harvesters, at the recommended rate of 1 g/t of fresh forage, to achieve a final application rate of 1.0 × 10(5) cfu/g of L. buchneri. One corn bunker silo, which had been open for at least 10 d, was examined in detail on each farm. The silages inoculated with L. buchneri had lower concentrations of lactic acid, a lower lactic-to-acetic acid ratio, a lower yeast count, and higher aerobic stability compared with the untreated silages. Unexpectedly, concentrations of acetic acid and 1,2-propanediol, 2 hallmarks of L. buchneri activity, did not differ between treatments and were only numerically higher in the inoculated silages compared with untreated ones, in both surveys. Aerobic stability, on average, was 107 and 121 h in the inoculated silages and 64 and 74 h in the untreated silages, for surveys 1 and 2, respectively, and decreased exponentially as the yeast count in the silage at the time of sampling increased, regardless of treatment. Inoculation with L. buchneri proved to be effective in reducing the yeast count to <2 log cfu/g of silage in 16 of 21 of the studied farm silages, confirming the ability of this inoculum to enhance the aerobic stability of corn silages in farm bunker silos.

The relationship of silage temperature with the microbiological status of the face of corn silage bunkers.

A method is proposed to quantify aerobic deterioration of corn silage forage quality as related to the temperature of silage mass in the bunker. Aerobic deterioration, apart from causing nutritional value losses, affects the hygienic quality of silages through the accumulation of pathogenic organisms and their toxins. A survey was carried out in northern Italy that involved a detailed examination of silage bunker from each of 54 dairy farms. Samples from the core, the peripheral areas within 1m from the silo walls, and the molded spots, when present, were collected. The sample and silage temperatures across the working face were measured at depths of 200 mm at 11 locations and at 7 elevations. The temperature of the central zone of the silo was defined as the reference temperature (T(ref40)). The difference between the temperature of the silage sample and the T(ref40) was used as a heating index associated with aerobic deterioration (dT(ref40)). The working face area with visible molds was measured. The samples were analyzed for DM content; pH; water activity; nitrates; lactic, acetic, and butyric acids; and microbiological count of yeasts, molds, and clostridia spores. The core samples always showed a pH below 4.0 and a dT(ref40) below 2 degrees C, whereas the silages from the peripheral areas were split into 2 groups, one that had a pH lower than 4 and a dT(ref40) lower than 3.5 degrees C (53%) and one that had a pH higher than 4 and a dT(ref40) higher than 5 degrees C (47%). Most of the silages from the peripheral areas (94%) and all the silages from the moldy spots that have a dT(ref40) above 5 degrees C had a pH higher than 4.5. Furthermore, a positive dT(ref40) higher than 5 degrees C corresponds to a higher yeast count than 5 log cfu/g in most of the silages from the peripheral areas (93% of samples) and in almost all the silages from the molded spots. The evaluation of the extension of the visible molded areas combined with temperature measurement at 200 mm behind the feed-out face could offer a good indication of the health status of silage during consumption. Furthermore, this method could be useful to detect early stages of the aerobic deterioration process and to improve silage management.

Clostridia spore formation during aerobic deterioration of maize and sorghum silages as influenced by Lactobacillus buchneri and Lactobacillus plantarum inoculants.

AIMS: The effect of the inoculation of maize and sorghum silages with Lactobacillus plantarum (LP) and Lactobacillus buchneri (LB) on the clostridia spore formation during aerobic deterioration has been studied. METHODS AND RESULTS: The crops were ensiled in 30 l jars, without a lactic acid bacteria inoculant (C), and with an LP or LB inocula (theoretical rate of 1 x 10(6)). After 90 days of conservation, the silages were analysed for the chemical and microbiological characteristics and subjected to an aerobic stability test, during which pH, temperature, nitrate, yeast, mould and clostridia spores were measured. Compared to the C and LP silages, yeasts were reduced in the LB silages, resulting in an increased aerobic stability. Clostridia spores, determined by most probable number (MPN) procedure, increased to 6 log(10) MPN g(-1) in the C and LP maize silages, whereas they reached 3 log(10) MPN g(-1) in C and LP sorghum silages. CONCLUSIONS: Clostridia spore count only slightly increased in the LB maize silages after 342 h (2.59 log(10) MPN g(-1)), whereas it did not show any increase in the LB sorghum silages for the whole period of air exposure. SIGNIFICANCE AND IMPACT OF THE STUDY: The data indicated that clostridia spore outgrowth can take place during silo feedout in aerobic-deteriorated silages and that LB inoculation reduces the risk of clostridia outgrowth after silage opening by increasing the aerobic stability.

Low permeability to oxygen of a new barrier film prevents butyric acid bacteria spore formation in farm corn silage.

The outgrowth of Clostridium spore-forming bacteria causes late blowing in cheeses. Recently, the role of air diffusion during storage and feed-out and the role of aerobic deterioration has been shown to indirectly favor butyric acid bacteria (BAB) growth and to determine the presence of high concentrations of BAB spores in farm tank milk. A new oxygen barrier (OB) film was tested and compared with conventional polyethylene (ST). The objective was to verify whether the OB film could prevent BAB spore formation in whole-crop corn silage during storage on 2 commercial farms with different potential silage spoilage risks. Two bunkers (farms 1 and 2) were divided into 2 parts along the length so that half the feed-out face would be covered with ST film and the other half with OB film. Plastic net bags with freshly chopped corn were buried in the upper layer and in the central part (CORE) of the bunkers. The silos were opened in summer and fed out at different removal rates (19 vs. 33 cm/d). Herbage at ensiling, silage at unloading, and silage after air exposure (6 and 15 d) were analyzed for pH, nitrate, BAB spores, yeasts, and molds. The BAB spores in herbages at ensiling were 2.84 log(10) most probable number (MPN)/g, with no differences between treatments or farms. Nitrate was below the detection limit on farm 1 and exceeded 2,300 mg/kg of fresh matter on farm 2. At unloading, the BAB spores in the ST silage on farm 1 were greater than 5 log(10) MPN/g, whereas in the CORE and the OB silages, they were approximately 2 log(10) MPN/g. The ST silage had the greatest pH (5.89), the greatest mold count (5.07 log(10) cfu/g), and the greatest difference between silage temperature and ambient temperature (dT(section-ambient)). On farm 2, the ST silage had the greatest concentration of BAB spores (2.19 log(10) MPN/g), the greatest pH (4.05), and the least nitrate concentration compared with the CORE and the OB silages. Pooled data on BAB spores collected from aerobically deteriorated samples showed a positive relationship with pH, mold count, and dT(section-ambient) and a negative relationship with nitrate concentration. A high concentration of BAB spores (>5 log MPN/g) was associated with visible spoilage, high pH values (>5.00), high mold counts (>5 log cfu/g), high dT(section-ambient), and nitrate below 1,000 mg/kg of fresh matter. We concluded that the use of a film with reduced oxygen permeability prevented the outgrowth of BAB spores during conservation and feed-out, and it could improve the microbiological quality of corn silage by eliminating the fractions of silage with high BAB spore concentrations.

A new oxygen barrier film reduces aerobic deterioration in farm-scale corn silage.

Recently, many studies have focused on the aerobic deterioration of corn silage at the farm level, because a large part of the product stored in horizontal silos is exposed to air and is more prone to spoilage. The most important factor influencing the preservation of forage ensiling is the degree of anaerobiosis that is usually achieved with sheets of polyethylene. A new black-on-white (125-microm) coextruded oxygen barrier (OB) film has been developed for silage sealing and was tested in the present experiment to assess the effects on fermentation quality, dry matter losses, and yeast and mold counts at opening of whole-crop corn bunker silos compared with conventional polyethylene (ST) film. Two trials were carried out on 2 commercial farms. The bunkers were divided into 2 parts along the length so that half of the feedout face would be covered with ST film and the other half with OB film. Eight plastic net bags with well-mixed fresh material were weighed and buried in the upper layer of the bunker, and 4 bags were buried in the central part. The silos were opened for summer consumption and were fed out at different rates (19 vs. 33 cm/d). The bags were unloaded, weighed, and subsampled to analyze the DM content, pH, lactic and monocarboxylic acids, ammonia, yeast and mold counts, and aerobic stability. The pH of the peripheral silage was different under the 2 films, with a lower value in the OB treatment. The OB film on farm 1 affected the silage dry matter losses, which were reduced 3.7 times in comparison with the ST film sealing. On farm 2, although the dry matter losses were numerically higher in the silage sealed with the ST film compared with OB film (9.0 vs. 5.9%, respectively), the difference was not statistically significant. However, the corn silage sealed with the ST film was less stable than the silage sealed with the OB film. The results indicate that the new OB film is a promising tool to constrain spoilage and dry matter losses under critical farm conditions, when inadequate amounts of silage are removed daily. The OB film further improved the stability of the corn silage in the peripheral areas of the silos even when a proper harvest-to-feedout management was implemented.

Comparison of hay and haylage from permanent Alpine meadows in winter dairy cow diets.

In an Alpine environment, diets based on local forage resources are needed to maintain the link with the territory and confer special characteristics to typical cheeses. Harvesting at a late stage of maturity, high mechanical losses, and frequent rainfall often make the hay that is harvested of a poor quality. The aim of this study was to evaluate the effects of 2 different conservation methods (late hay, LH, vs. early haylage, ES) of natural permanent meadows on milk production in dairy cows, on the chemical and microbiological characteristics of the milk, and on the quality of the cheese over the winter period. Haylage and hay were harvested from the same permanent meadow at the Vittorino Vezzani experimental farm in Sauze d'Oulx (45 degrees 02'N, 6 degrees 53'E, Italy). The ES forage was cut 4 wk earlier than traditional hay, wilted for 30 h, baled at a dry matter (DM) content of about 50%, wrapped with 6 layers of stretch film, and stored in a protected area. The LH forage was harvested later, when the weather conditions were favorable and, after a 3-d wilting, it was baled and stored indoors. After an 8-mo storage period, the ES had a greater crude protein concentration, organic matter digestibility, and net energy for lactation than LH and a lower neutral detergent fiber and acid detergent fiber. Forty multiparous lactating Aosta Red Pied cows were used in a 19-d period crossover design to assess the nutritional value of the stored forages. The diets included ES fed ad libitum and 3.5 kg of DM per cow of concentrate or LH fed ad libitum and 5.1 kg of DM per cow of concentrate. The dietary DM was 90.1% for the LH and 59.9% for the ES. The diets contained 12.6 and 13.0% crude protein and 48.6 and 48.0% neutral detergent fiber, for the LH and ES, respectively. The forage intake was greater in the ES treatment than in the LH treatment. The ES treatment produced more milk (1.7 kg/d) and more 3.5% fat-corrected milk (1.5 kg/d) than the cows on the LH treatment. The milk fat and protein concentrations were similar in both diets, resulting in a greater protein yield in the ES treatment. The lactose, pH, total bacterial count, and somatic cell count were not different for the treatments. The clostridial spores did not differ between the treatments from preharvest forage to cheese, and no differences were found in terms of cheese quality after maturation. Conserving forage as wrapped bale silage combined with an earlier harvesting date than traditional hay resulted in a suitable method to improve forage quality without increasing the risk of clostridial contamination in the milk and cheeses.