The stable isotope ratios ( 13 C/ 12 C, 15 Recently, several papers have been published about the application of stable isotope ratio analysis (SIRA) using isotopic ratio mass spectrometry (IRMS) to animal products. The aims of these studies were to obtain dietary reconstruction, to study animal movement patterns, 1-5 and to characterise the geographical origin. [6][7][8][9][10][11][12][13][14][15][16] Another important aim could be to study and quantify the alteration of stable isotope ratios (SIRs) in milk by substituting a C 3 plant diet with maize. This could be important in order to protect milk and milk derivatives produced using traditional or 'organic' practices of pasture compared with products produced with cheaper diets based on maize derivatives. There have been recent reports about this in defatted meat, [17][18][19] in related fat, 17 in several animal tissues such as blood, plasma, liver, kidney, cow hair 20 and in sheep faeces. 21 In these papers it was shown that there is a strong correlation between the SIR of carbon and the amount of maize in the diet. It was also shown that the degree of this alteration depends on the component or body tissue considered, due to its biochemical composition and turnover rate. 22 On the other hand, variations in the SIRs in milk and milk derivatives following suitable experimental design have not been so extensively explored. Metges et al. 23 investigated the 13 C/ 12 C of CO 2 breath, bulk milk and serum by exchanging a C 3 plant with a C 4 plant diet, and vice versa. Wilson et al. 24 studied the contribution of body protein to milk protein, changing abruptly from a C 3 to a C 4 diet. More recently, Knobbe et al. 25 followed the variation in stable carbon and nitrogen isotopic composition under different feeding regimes. It was concluded that, to obtain more detailed information on the influencing factors, the analysis of the SIRs of other elements such as oxygen and hydrogen may be necessary.In this study we considered around 130 cows stabled in two farms and supplied with diets made up of different kinds of C 3 plants and different amounts of maize. The different feed ingredients, the overall diet and the relevant milk (casein, lipid and some bulk samples) were subjected to analysis of 13

No abstract

No abstract

The effects of the addition of tannins to lucerne silage were investigated. At ensiling, chestnut hydrolyzable tannins were added to lucerne forage (T=tannins treated lucerne silage vs C=control lucerne silage). Fifty lactating Holstein cows, fed two diets different for lucerne silage treatment (C or T), were used in a cross-over design. In situ rumen soluble protein fraction (%CP) was higher for C (67.9 vs 59.4; P<0.01), whereas potentially rumen degradable protein (%CP) was lower (24.5 vs 32.1 for C and T; P<0.01). Intestinal rumen escape protein digestibility (%) was numerically higher for T (48.3 vs 54.3). Dry matter intake (21.5 kg/d for both diets) and milk yield (29.8 and 30.2 kg/d for C and T) were not affected by dietary treatment, whereas FCM was slightly higher for T diet (27.5 vs 27.9 kg/d for C and T; P<0.10). Adding tannins to lucerne silage is effective in shifting part of N utilization from the rumen to the intestine, leading to similar productive performance in lactating cows

Three experiments were carried out to study the effects of feeding lucerne silage (wilted to give different drymatter (DM) contents) and ventilated hay to dairy cows on milk production, milk quality, milk-renneting properties, clostridial spore content and the quality of cheese prepared from the milk. The lucerne, cut at vegetative or early-bud stages of maturity, was harvested from alternate windrows and conserved as silage or arti®cially dried hay. The lucerne was wilted until it reached different DM contents of 550, 360 and 432 g kg ±1 in the three experiments, harvested, chopped with a selfloading forage wagon and ensiled in low and narrow clamps made up of transferable prefabricated walls. The organic acid content, pH, yeast and mould counts of the lucerne silage suggested that there was no aerobic deterioration.In each experiment, ®fty Italian Friesian lactating cows were divided into two groups and fed two maize silage-based rations for 6 weeks, which only differed in the lucerne forage [silage (S) vs. ventilated hay (H)], in a cross-over experimental design. The lucerne in the rations represented 35%, 23% and 24% of the DM of the rations for the three experiments. The microbiological pro®les of the ration were in¯uenced more by the maize silage than by the lucerne silage.Individual daily DM intakes were similar for the two treatments in Experiments 1 and 3 (on average 18á7 kg in Experiment 1 and 20á3 kg in Experiment 3) and slightly lower for S cows in comparison to H cows in Experiment 2 (18á0 vs. 19á0 kg). Milk yields of S and H cows were 21á0 and 20á8, 20á0 and 20á6 (P < 0á01), and 28á4 and 27á9 kg d ±1 in Experiments 1, 2 and 3 respectively. Milk composition was similar for all the experiments for the two treatments, except that the protein content was lower and the fat content was higher in the silage treatment than in the hay. The renneting properties and microbiology of the milk were not in¯uenced by the introduction of lucerne silage into the rations, although the season in which it was consumed had a greater effect on the microbiological content, in terms of standard bacterial counts, proteolytic, coli and lactic acid bacteria, and clostridia spores. The clostridial spore counts were always very low (< 400 per litre), thus ful®lling the requirements for top-quality milk for Grana cheese production. In the third experiment, the quality of Grana Padano cheese produced was examined, and no differences between treatments were observed after 12 months of maturation.These results show that lucerne silage can be included in the ration of dairy cows instead of ventilated lucerne hay, which is considered to be the top-quality hay available for the production of milk destined for Grana cheese, without any negative effects on milk and cheese quality.