Alberto Tamburini

Redox potential to discriminate among species of lactic acid bacteria

Aims:  To verify to what degree reducing capacity is a characterizing parameter of a species, and of the strains themselves within a given species, of lactic acid bacteria.

Energy and nitrogen balance in heavy pigs fed different fibre sources

The aim of the experiment was to investigate the possible differences in the utilization of different fibrous feeds by the heavy fattening pig. Eight Landrace×Large White barrows of 85 kg BW were paired and fed, in a Latin Square design, four diets containing different dietary fibre sources: 8% coarse soft wheat bran (control, C), 24% milled wheat bran (MB), 24% coarse wheat bran (CB), and 16% dried beet pulp (BP). Compared to C, the MB and CB diets significantly decreased the digestibility of most parameters, while the BP diet lowered the digestibility of N and EE, increased fibre digestibility, and had similar DM, OM and energy digestibility. Compared to BP, diets MB and CB had significantly higher N and EE digestibility, but lower DM, OM, fibre and energy digestibility. CH4 emission was significantly increased by BP compared with C, MB and CB. Compared to C, metabolisable energy was significantly lowered by MB and CB, but not by the BP diet. The BP diet caused significantly (P<0.01) greater heat production (47.3% of intake energy) than the MB (45.2%) and CB (45.0%) diets; heat production for diet C was intermediate (46.4%). The retained energy and N retention were similar for all treatments. MB and BP diets had significantly lower NE than the other two diets. The results suggest that, because the heavy pig can use dietary fibre better than younger pigs, wheat bran and beet pulp have a higher energy content than reported from trials on animals of lower bodyweight.

Effect of the stage of maturity on the nutritive value of whole crop wheat silage

Abstract An in vivo digestibility and calorimetric experiment was performed on eight adult wethers to determine the digestibility and net energy content of wheat silages obtained from whole plants cut at different stages of maturity. Wheat ( Triticum aestivum L., var. Eridano) was harvested at the boot (B), midbloom (MB), milk (M) and dough (D) stages of maturity. The wethers were fed ad libitum in a 4×4 latin square digestibility trial. Each collection period lasted eight days with 3×24 h-cycles of respiration trials (indirect calorimetry in respiration chambers). In vitro organic matter digestibility (IVOMD) was determined on dried samples of whole wheat cut from the same field at 10 different stages between boot and dough. Silage quality parameters were optimum for all stages. DM, OM and energy intake were significantly higher in the first and last stages of maturity (B and D) than in the medium stages (MB and M). DM, OM and energy digestibility decreased significantly from B to M stage but did not change between the last two stages. In contrast, CF, NDF and ADF digestibility decreased significantly with maturity. IVOMD had a quadratic trend of variation as a function of the stage of maturity, similar to the in vivo data, with the lower value at the M stage. Metabolizability ( q =ME/GE) followed the same trend of energy digestibility. NE l decreased with increasing stage of plant growth but the difference was significant only between the first stage and the last three stages. The nutritive values of the whole-crop wheat silages was very high for the B stage and decreased with successive stages of maturity (7.74, 6.41, 5.69 and 5.39 MJ NE l /kg DM at the B, MB, M and D stages). In contrast, DM yield was minimum at the B stage (3.3 t/ha) and increased with increasing maturity up to 9.6 t/ha at the D stage. As a consequence, a satisfactory compromise between yield and nutritive value would involve harvesting whole-crop wheat just before the milk stage.

Effect of cleaning procedure and hygienic condition of milking equipment on bacterial count of bulk tank milk.

The aim of the study was to describe the characteristics of cleaning procedures for milking equipment applied in intensive dairy farms in Lombardy (Italy) and to study their relationships with bacterial count of bulk milk and hygienic condition of milking machine components. A group of 22 dairy farms was visited twice (winter and summer) in order to collect bulk tank milk and post-rinse water samples and swabs from liners and milk receiver. Samples were analysed to determine: standard plate count (SPC), laboratory pasteurization count (LPC), psychrotrophic bacteria count (PBC), coliform count (CC) and Escherichia coli. Cleaning procedures were monitored using electronic milk flow meters with specific software for the measurement of the duration of each cleaning phase, circulating solution temperature and electrical conductivity, turbulence and water filling percentage of pipelines. The results showed that farms classified as high and low milk total bacteria count significantly differed both in terms of liners and receiver bacterial contamination and in terms of water temperature reached during the detergent phase of cleaning milking equipment. Significant positive correlations were found among total bacteria count in milk and bacterial contamination of the liners. Maximum water temperature reached during the cleaning cycle of milking equipment was very low (34.4±8.9°C on average); most of the observations (88.6%) corresponded to water temperatures <45°C. Cleaning temperature was related to psychrotrophic bacteria count of milk and post-rinse water and coliform count in liners. Routine check and regulation of water temperature during the washing phase of the milking machine can be a simple and effective way to control one of the main risk factors for bacteriological quality of bulk tank milk.

How can farming intensification affect the environmental impact of milk production

The intensification process of the livestock sector has been characterized in recent decades by increasing output of product per hectare, increasing stocking rate, including more concentrated feed in the diet, and improving the genetic merit of the breeds. In dairy farming, the effects of intensification on the environmental impact of milk production are not completely clarified. The aim of the current study was to assess the environmental impacts of dairy production by a life cycle approach and to identify relations between farming intensity and environmental performances expressed on milk and land units. A group of 28 dairy farms located in northern Italy was involved in the study; data collected during personal interviews of farmers were analyzed to estimate emissions (global warming potential, acidification, and eutrophication potentials) and nonrenewable source consumption (energy and land use). The environmental impacts of milk production obtained from the life cycle assessment were similar to those of other recent studies and showed high variability among the farms. From a cluster analysis, 3 groups of farms were identified, characterized by different levels of production intensity. Clusters of farms showed similar environmental performances on product basis, despite important differences in terms of intensification level, management, and structural characteristics. Our study pointed out that, from a product perspective, the most environmentally friendly way to produce milk is not clearly identifiable. However, the principal component analysis showed that some characteristics related to farming intensification, such as milk production per cow, dairy efficiency, and stocking density, were negatively related to the impacts per kilogram of product, suggesting a role of these factors in the mitigation strategy of environmental burden of milk production on a global scale. Considering the environmental burden on a local perspective, the impacts per hectare were positively associated with the intensification level.

Effects of season, milking routine and cow cleanliness on bacterial and somatic cell counts of bulk tank milk

The aim of the study was to investigate the effects of season, cow cleanliness and milking routine on bacterial and somatic cell counts of bulk tank milk. A total of 22 dairy farms in Lombardy (Italy) were visited three times in a year in different seasons. During each visit, samples of bulk tank milk were taken for bacterial and somatic cell counts; swabs from the teat surface of a group of cows were collected after teat cleaning and before milking. Cow cleanliness was assessed by scoring udder, flanks and legs of all milking cows using a 4-point scale system. Season affected cow cleanliness with a significantly higher percentage of non-clean (NC) cows during Cold compared with Mild season. Standard plate count (SPC), laboratory pasteurization count (LPC), coliform count (CC) and somatic cell count, expressed as linear score (LS), in milk significantly increased in Hot compared with Cold season. Coagulase-positive staphylococci on teat swabs showed higher counts in Cold season in comparison with the other ones. The effect of cow cleanliness was significant for SPC, psychrotrophic bacterial count (PBC), CC and Escherichia coli in bulk tank milk. Somatic cell count showed a relationship with udder hygiene score. Milking operation routine strongly affected bacterial counts and LS of bulk tank milk: farms that accomplished a comprehensive milking scheme including two or more operations among forestripping, pre-dipping and post-dipping had lower teat contamination and lower milk SPC, PBC, LPC, CC and LS than farms that did not carry out any operation.

Anaerobic digestion and milking frequency as mitigation strategies of the environmental burden in the milk production system.

The aim of the study was to assess, through a cradle to farm gate Life Cycle Assessment, different mitigation strategies of the potential environmental impacts of milk production at farm level. The environmental performances of a conventional intensive dairy farm in Northern Italy (baseline scenario) were compared with the results obtained: from the introduction of the third daily milking and from the adoption of anaerobic digestion (AD) of animal slurry in a consortium AD plant. The AD plant, fed only with animal slurries coming also from nearby farms. Key parameters concerning on-farm activities (forage production, energy consumptions, agricultural machines maintenance, manure and livestock management), off-farm activities (production of fertilizers, pesticides, bedding materials, purchased forages, purchased concentrate feed, replacement animals, agricultural machines manufacturing, electricity, fuel) and transportation were considered. The functional unit was 1kg fat and protein corrected milk (FPCM) leaving the farm gate. The selected environmental impact categories were: global warming potential, acidification, eutrophication, photochemical oxidation and non-renewable energy use. The production of 1kg of FPCM caused, in the baseline scenario, the following environmental impact potentials: global warming potential 1.12kg CO2 eq; acidification 15.5g SO2 eq; eutrophication 5.62g PO4(3-) eq; photochemical oxidation 0.87g C2H4 eq/kg FPCM; energy use 4.66MJeq. The increase of milking frequency improved environmental performances for all impact categories in comparison with the baseline scenario; in particular acidification and eutrophication potentials showed the largest reductions (-11 and -12%, respectively). In anaerobic digestion scenario, compared to the baseline one, most of the impact potentials were strongly reduced. In particular the most important advantages were in terms of acidification (-29%), global warming (-22%) and eutrophication potential (-18%). The AD of cow slurry is confirmed as an effective strategy to mitigate the environmental impact of milk production at farm level.

Management practices and forage quality affecting the contamination of milk with anaerobic spore-forming bacteria

BACKGROUND Anaerobic spore-forming bacteria (ASFB) in milk derive from the farm environment, and the use of silages and management practices are the main responsible of milk ASFB contamination. The aim of this study was to evaluate the relationships between feeding, milking routine and cow hygiene and milk and Grana Padano cheese (produced with and without lysozyme) ASFB contamination. RESULTS The study involved 23 dairy farms. ASFB in corn silage were on average 2.34 ± 0.87 log10 MPN g(-1). For grass, Italian ryegrass and alfalfa, ASFB (log10 MPN g(-1)) were numerically higher for silages (3.22) than hays (2.85). The use of corn silages of high quality (high lactic and acetic acids concentrations) decreased the milk ASFB contamination, whilst the use of herbage silages did not affect it. The presence (>40%) of cows with dirty udders increased the ASFB contamination of milk, while forestripping had a positive effect (-9% ASFB). Ripened Grana Padano had an ASFB count below the analytical limit; Clostridium tyrobutyricum DNA was found only in wheels produced without lysozyme, which also showed late blowing. CONCLUSION The factors increasing milk spore contamination were corn silage quality, cow udder hygiene and inadequate milking routine. Late blowing was present only in cheeses without lysozyme.

Effect of maize, rumen-protected fat and whey permeate on energy utilisation and milk fat composition in lactating goats

Abstract The efficiency of utilisation of diets with different proportions of energy sources (starch, fat, lactose) was studied with three pairs of lactating Saanen goats; the animals were fed, in a Latin square design, 3 silage-based diets containing (on DM basis) the following energy sources: 32% maize meal (diet M); 4.7% rumen-protected fat (Megalac®) and 23.5% maize meal (diet F); 9.8% milk whey permeate powder and 22.3% maize meal (diet W). During each of the three experimental periods, 8 days of total collection balance trials were conducted during which goats were allocated for 72 h (three 24 h cycles) in open circuit respiration chambers to determine methane and heat production and, hence, the energy balance. Diet F, in comparison with diets M and W, significantly increased the milk fat content (4.13 vs 3.11 and 3.14%, P<0.001) and the 4%-FCM yield (3367 vs 2927 and 3055 g/d, P<0.01 and P<0.05, respectively), while no relevant changes were observed for milk protein content and yield. Energy digestibility was equal in diets F and W. Megalac® did not decrease fibre digestibility. The partition of the gross energy intake (EI) differed significantly between diets: diet M had lower DE (72.4 vs 74.3 and 74.3%; P<0.01) and ME (62.1 vs 64.7 and 63.5%; P<0.05) in comparison with diets F and W, respectively. Energy lost as methane was not significantly decreased by the inclusion of rumenprotected fat in the diet, although a trend for a reduction of methanogenesis was observed. Heat production determined by treatment F was lower in comparison with the other treatments. This difference was almost significant (P=0.056) when expressed as a percentage of the ME. Milk energy output increased significantly (+12%, P<0.001) by including fat in the diet, as compared with treatments M and W: 21.4 vs 19.1 and 19.0% of the EI. The net energy content of the protected fat was 27.94 MJ NEl/kg DM (+340% vs maize meal); its kl value resulted 0.77. The corresponding values for whey permeate were 7.76 MJ NEl/kg DM (-5% vs maize meal) and 0.50, respectively. Summarizing, the efficiency of energy utilization in diet M was significantly lower in comparison with the other two diets in terms of digestibility and metabolisability, while its NEl content was similar to that of diet W. On the other hand, diet F had a significantly higher ME (P<0.01) and NEl (P<0.05) as compared to the other two diets. Diet F greatly influenced the fatty acid composition of the milk fat with less short (-30%) and medium (-33%) chain fatty acids and more (+18%) long chain fatty acids. In conclusion, whey permeate and even more Megalac® can be successfully used as feed ingredients in the diet of highly productive lactating goats, but the economical convenience of their utilisation must be evaluated based on the market values of feedstuffs.

Effects of Liner Compression on Teat-End Hyperkeratosis

The teat canal is an important barrier against microorganism invasion of the udder. The degree of teat-end hyperkeratosis (HK) is a dynamic condition. Development of HK is influenced by many factors: some animal dependent, some dependent from seasonal condition and some from milking management. In particular milking vacuum and liner compression (LC) can influence teat-end condition. A quarter-udder experiment was performed with four liners each applied one quarter of 75 Holstein cows for a period of 3 weeks. Teat-end HK was assessed weekly. The results of this study confirm that the risk developing HK increases with liners that apply greater pressure to the teat end when closed. The risk of developing HK was highly influenced by the duration of milking and initial teat-end HK score.