Giorgio Marchesini

Effect of induced ruminal acidosis on blood variables in heifers

BackgroundRuminal acidosis is responsible for the onset of different pathologies in dairy and feedlot cattle, but there are major difficulties in the diagnosis. This study modelled the data obtained from various blood variables to identify those that could indicate the severity of ruminal acidosis. Six heifers were fed three experimental rations throughout three periods. The diets were characterised by different starch levels: high starch (HS), medium starch (MS) and low starch, as the control diet (CT). Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis. Blood samples were analysed for complete blood count, biochemical profile, venous blood gas, blood lipopolysaccharide (LPS) and LPS-binding proteins (LBP).ResultsThe regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040). Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3- (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001). A canonical discriminant analysis (CDA) was used to classify the animals into four ruminal pH classes (normal, risk of acidosis, subacute ruminal acidosis and acute ruminal acidosis) using haemoglobin, mean platelet volume, β-hydroxybutyrate, glucose and reduced haemoglobin.ConclusionsAlthough additional studies are necessary to confirm the reliability of these discriminant functions, the use of plasma variables in a multifactorial model appeared to be useful for the evaluation of ruminal acidosis severity.

Effect of feeding fine maize particles on the reticular pH, milk yield and composition of dairy cows

The particle size of cereal grains has been found to modulate the rate of passage from the rumen and the digestibility of starch and neutral detergent fibre (NDF), but few studies have examined its impact on reticular pH. The study aimed to evaluate the effect of feeding finely ground maize on the risk of ruminal acidosis, milk yield and composition. Twelve Holstein-Friesian cows were assigned to one of two experimental groups and fed according to a cross-over design. Diets were isoenergetic and isonitrogenous and were characterised by the same NDF and ADF, differing only in maize particle size. In the control diet (Ct), the maize meal was ground to 1.0 mm, whereas in the experimental diet, it was finely ground (Fg) to 0.5 mm. The pH and temperature of the reticulum were continuously measured in eight cows throughout the trial using indwelling sensors. Dry matter intake was higher in cows offered Fg diet than in Ct (19.0 vs. 20.3 kg/day; p = 0.067). However, milk yield (p = 0.855) and the 3.5% fat-corrected milk (FCM) (p = 0.724) did not show any differences between the diets. Casein (2.48 vs. 2.57%; p = 0.035) and crude protein (CP) (3.18 vs. 3.31%; p = 0.021) resulted higher in Fg. Similarly, starch digestibility increased in animals offered Fg diet versus Ct (0.94 vs. 0.98; p = 0.078). Among the reticular parameters, the Fg-fed cows spent a significantly higher time below the 5.5 pH threshold (15 vs. 61 min/day; p = 0.047) and had an average daily variation in reticular pH characterised by a lower nadir pH (5.95 vs. 5.72; p < 0.001) and a higher pH range (0.79 vs. 0.94; p = 0.003). In this study, grain particle size affected the risk of the onset of ruminal acidosis. Therefore, it should be carefully considered when formulating rations.

Relationship between milk fatty acid composition and dietary roughage source in dairy cows

According to a 2 × 2 crossover design, 14 Holstein dairy cows were fed two isoenergetic diets based on either grass hay (GH) or maize silage (MS). Milk samples were collected during the third week of each period, and fatty acid (FA) profiles were analyzed using gas chromatography. The data obtained were subjected to ANOVA. Dietary treatment had no effect on either dry matter intake or milk yield. Milk from animals fed the GH-diet contained lower concentrations of saturated FAs (61.9 vs. 63.4% of total FAs; P < 0.05) and higher levels of polyunsaturated FAs (PUFAs) (6.1 vs. 5.8; P < 0.01). Feeding additional hay also increased conjugated linoleic acid and n-3 FA levels and decreased C16:0 levels. Increases in both PUFAs and n-3 FAs resulted in lower (P < 0.01) atherogenic and thrombogenic indices in milk from animals fed the GH diet compared with those fed the MS diet. A complete substitution of GH for MS appeared to improve milk FA profiles, even using different types of concentrates to provide a balanced diet.

Effect of unsaturated fatty acid supplementation on performance and milk fatty acid profile in dairy cows fed a high fibre diet.

Abstract The influence of unsaturated fatty acid (UFA) supplement on productive performance, physiochemical properties and fatty acid (FA) profile of milk, was investigated in lactating dairy cows fed with high fibre diets. According to a cross-over design, twelve cows were assigned to two experimental settings characterized by different FA profiles. Cows received a high fibre diet (~42% NDF on DM basis) supplemented with soybean based mixtures with these FA compositions: 92.0% of saturated FA (SFA), 2.8% of monounsaturated FA (MUFA) and 5.2% of polyunsaturated FA (PUFA) in the control diet (C-diet); 19.1% of SFA, 20.9% of MUFA and 60.0% of PUFA in the experimental diet (E-diet). The E-diet did not affect dry matter intake nor milk yield. Milk composition and coagulation traits resulted similar between treatments, except for the lactose level, which was lower in the E-diet (5.0 vs 4.8%; P<0.05) and the freezing point (-0.546 vs -0.535 °C; P<0.05). As respects the milk FA profile, the E-diet significantly increased the percentage of UFA because of their greater amount in the ration; however the “transfer” of UFA in milk was limited by the high level of FA biohydrogenation (BH) at the ruminal level. UFA showed low values of carry over in milk (67.5 vs 39.7%; P<0.001) due to the saturation process; on the contrary SFA had a threefold increment (124 vs 323%; P<0.001), mostly due to a peak in the production of stearic acid. In this study, the percentage of CLA in milk (0.50 vs 0.62%; P<0.05) was quite low for both diets, if compared with other studies, and this was probably due to a low vaccenic acid supply at duodenal level.

A comparison of nitrogen use efficiency and surplus in two dairy farms typologies

Abstract Referring to the Destra Brenta district (Veneto Region, Italy) two farming systems were considered: grassland-hay (H) vs. arable land-silage maize (M). Manure and crop products belonged to an internal flow, thus an annual farm gate balance of nitrogen (N) was carried out to determine the nutrient use efficiency (NUE) and surplus by using data from a survey. Surplus was determined as difference between inputs (I) and outputs (O) and NUE as ratio between O and I. The main I was represented by purchased concentrate, on the contrary fertilizer accounted only for low amounts. Surplus per surface unit was significantly higher in M-farms group than in H one (269 vs. 369 kg N per ha; P<0.01). Surplus referred to unit of fat corrected milk was significantly lower in M-farms (17.6 vs.15.6 kg of N per ton of FCM; P<0.01) leading to an higher N-NUE (0.260 vs. 0.278; P<0.05).

Effect of non-forage roughage replacement on feeding behaviour and milk production in dairy cows

The objective of this study was to determine whether the partial replacement of roughage from forage with non-forage fiber sources, in a total mixed ration (TMR), could reduce feed sorting by dairy cows without modifying behaviour and milk production. Twelve Holstein cows were fed two TMR maize silage based diets in a cross-over experiment. Compared to the control diet (C-diet), experimental diet (E-diet) was formulated by replacing 8% neutral detergent fibre (NDF) from straw and alfalfa hay with soybean hulls and wheat bran. E-diet had a lower physical effectiveness factor (pef) (0.37 vs 0.34; P<0.001) and physical effective NDF (peNDF) (15.5 vs 14.6%; P<0.01). Feeding and sorting behaviour, ruminal activity, milk yield and composition and blood metabolites were measured. The results indicated that dry matter intake was not affected by diet. Cows fed the experimental TMR spent less time eating (192 vs 178 min/d; P<0.05) but showed the same number of meals per day. C-diet fed cows sorted against peNDF in a greater extent (98.3 vs 100.9%; P<0.05). Treatments did not affect cows time budget of general behaviours, with particular regard to ruminating activity. Despite different forage sources in TMR, no significant differences in milk yield and quality were detected.

Storage test on apple juice after ultrasound treatment

Apple juice, for its sensory and nutritional qualities, is consumed by people of all ages. Apples are an excellent source of several phenolic compounds and the presence of polyphenols is recognized for their health promoting antioxidant properties. Thermal pasteurization of fruit juices is the conventional method used for their preservation. Therefore, this constitutes the most extensively available methods for the inactivation of microorganisms in fruit juices but it causes side effects on their flavour and nutritional quality. Consumers tend to prefer recently extracted juices with fresh taste and minimal flavor or vitamin losses. To meet consumers’ demand, among the novel technologies that involve non-thermal processes, power ultrasound have been investigated as an alternative to conventional heat treatments. Objective of this study was to evaluate the effectiveness of the use of ultrasound in an attempt to maintain the organoleptic characteristics typical of a natural apple juice. In particular, it was evaluated the action on the microflora residing and shelf life of the product through microbiological and sensory analyses. Juice treated with ultrasound highlighted a reduction of aerobic mesophilic counts and psychrophilic bacteria respectively about 3 and 5 log CFU/mL and an enhanced yeast growth. The general opinion expressed by the panelist was in favour of the sonicated juice. This preliminary study showed that non-thermal methods such as power ultrasound technology may give new opportunities to develop fresh-like apple juice.

Effects of carbohydrase- inhibiting compounds on in vitro rumen fermentation

Batch culture fermentations with ruminal content were conducted to determine the effects of plant-derived [bilberry extract (BBE), phaseolamin, white mulberry (WMB), common flax] carbohydrase-inhibiting compounds on microbial fermentation. The cultures with these compounds, at two different doses (15 and 150 mg), were compared with both acarbose (ACB) and batch cultures without the addition of any enzyme-inhibiting compounds (Control). Incubations were conducted in triplicate and replicated. The pH, volatile fatty acids, ammonia N, apparent dry matter (DMD) and starch disappearance were measured after 5 and 24 h of incubation. Treatment with ACB, after 5 h, significantly reduced maize meal fermentation, resulting in the highest pH levels (P<0.01), the lowest total VFA concentration (P=0.01) and the lowest DMD (P<0.01). On the opposite, BBE and WMB caused the highest drop in pH, due to the rapid fermentation of their sugar content. Treatment with BBE resulted in an increase in propionate and in an apparently low ammonia N concentration, whilst ACB (150 mg) led to the highest values of acetate (P<0.05) and to a relative high concentration of ammonia N. After 24 h the differences in the fermentation pattern among supplements remained similar to those found after 5 h. In addition, BBE showed an activity against starch degradation, although this effect was concealed by the fermentation of sugars present in that supplement. These results show that some compounds modify the fermentation pattern of the substrate, but further studies are needed to clarify their impact on the complex rumen microbial community.

Use of rumination and activity data as health status and performance indicators in beef cattle during the early fattening period

The aim of this study was to measure the level of activity and rumination in young bulls and to assess whether these data can be used as indicators of health status and average daily weight gain (ADG). Two groups of animals (period 1: n=108 animals; period 2: n=106 animals) were fitted with sensors to measure daily activity and rumination, were weighed on arrival and at the end of the trial (70 days) and were checked twice daily to verify their health condition. Any clinical signs and therapies were recorded. The dishomogeneity index of rumination (DR), and the daily dishomogeneity indices of activity (DDA) and rumination (DDR), were calculated. Bulls had an ADG of 1.42±0.38kg/day and showed an average duration of daily rumination of 404±63min and an average activity of 474±46 bits, respectively. Animals characterised by low ADG had lower values of minimum daily rumination (P=0.01) and DDA (P<0.001), and a greater rumination range (P=0.007) and DR (P=0.003). Bovine respiratory disease and lameness were detected 31 and five times, respectively; among affected animals, the average daily activity, rumination and DDA were lower (P<0.05) at 3-6days before the onset of visible clinical signs, whereas DDR increased compared to the values when individuals were apparently healthy. The use of individual sensors appears promising for the early diagnosis of disease in beef cattle and for improving herd management.

Near infrared calibration transfer for undried whole maize plant between laboratory and on-site spectrometers

Abstract The analysis of the maize plant immediately after harvest is essential in order to check the composition and maturity of the plant to optimise the quality of silage. NIRS calibrations were carried out on chopped maize using three spectrophotometers: a laboratory instrument (FOSS NIRSystems 5000 scanning monochromator, FOSS, Silver Spring, MD) and two versions of new-generation portable instruments (poliSPECNIR, PL1 and PL2). The aim was to verify the quality of the transfer of the calibration curves between FOSS, PL1 and PL2 and between PL1 and PL2, obtained by three methods of spectra processing: pre-processing, piecewise direct standardisation (PDS) and direct standardisation (DS). Seventy-six samples of chopped whole maize plant were scanned with the three instruments and were analysed by wet chemistry for dry matter (DM), ash, crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), starch and total sugars, to develop calibration equations. Two more datasets of 15 samples each were used for the standardisation of equations and validation. The calibration transfer obtained, according to the values of R2, standard error of prediction and bias, can be considered satisfactory (0.72 > R2 <0.97) for DM, ash and NDF for both poliSPECNIR, while CP and ADF have shown a good accuracy of prediction (0.78 > R2 <0.82) with PL2. Using FOSS as a master instrument, the choice of method of standardisation varies depending on the slave instrument even though the best results are obtained using PDS with PL2. The most accurate predictions are reached using PDS even when PL1 is the master.