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The objective of this study was to evaluate the effects of a 12-wk inclusion of adsorbents (ADS) in the diet on hematology and milk yield of lactating dairy cows. In June 2005, 28 Italian Friesian cows were randomly assigned by parity, DIM, and previous milk yield to either be supplemented with 160 g/d per cow of adsorbents (80% clinoptilolite + 20% sepiolite) or to consume only the basal lactation diet (CON). Cows were milked in an automatic milking system that allowed daily milk recording. Blood samples were taken before TMR distribution (0730 h) before the trial start, and at 2, 4, 6, 8, 10, and 12 weeks of trial, to be analyzed for hematological parameters. Statistical analysis was performed by a randomized block design, with adsorbent supplementation (ADS vs. CON), milk yield level (high vs. low), and week of trial as main factors, with cow repeated in time. Cows fed ADS yield more milk than cows fed CON (27.6 vs. 25.1 kg/d respectively; P = 0.02). Adsorbents per se did not affect erythrocytes count, hemoglobin concentration (HGB), hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration, whereas week of trial did (P<0.001). There were no interactions between adsorbents and productive level (P>0.05) on erythrocyte features. There was interaction between adsorbents and week of trial for MCV (P<0.05), MCH (P<0.05), and also a trend was evidenced for HGB (P<0.10). The increase of MCV and HGB observed at the 2 final samplings in cows fed CON, and not observed in ADS cows, suggest a relative reduction in erythrocyte function. Considering the selectivity of the adsorbents used, a decreased availability of Fe or other micronutrients can be hypothesized. Our results can not be exhaustive concerning long term response of cow hematology to adsorbent inclusion in the diet; further research on micronutrients involved in erythrocyte functions (Fe and Cu) will be necessary. [ABSTRACT FROM AUTHOR]

The aim of this paper was to evaluate the effects of automatic milking (AM) on milk enzymes and minerals related to mammary epithelial integrity in comparison with twice-daily conventional milking (CM). One cow from each of 6 pairs of twins was assigned to be milked with AM or with CM throughout first lactation. Milk production was recorded and milk samples were collected at 4, 11, 18, 25, 32, and 39 wk of lactation (WOL) to determine fat and protein content, somatic cell count, pH, plasminogen (pl) and plasmin (Pl) activities, Na, K, and C1. Body condition score was monitored; blood samples were collected to determine energy-related metabolites in the first third of lactation (14 WOL), and plasma oxidative status throughout lactation. Overall mean and standard deviation of milking frequency (MF) in AM were 2.69 and 0.88, respectively. Milk production, fat and protein contents, and somatic cell count did not differ between milking systems. The pl and pl+Pl activities were lesser in AM than in CM. Milk pH was greater in AM than in CM. Milk Na, K, Na/K ratio, and Cl did not differ across the whole lactation. Milk pH had a positive correlation with milk Pl activity (r = 0.41), Na (r = 0.37), and Cl (r = 0.40) concentration, and negative correlation with the log10 of pl/Pl ratio (r = -0.47). The milk Na/K ratio had a positive correlation (r = 0.55) with milk P1 activity. Milking system (MS) did not seem to affect mammary epithelial permeability. The differences in enzymatic (proteolytic) activity due to the MS, probably related to daily MF, lead one to suppose that the quality of the protein fraction for the cheese-making process was preserved better with AM than with CM, even if differences in pH might negatively interfere. No difference triglycerides and nonesterified fatty acids, whereas plasma cholesterol concentration during the first 10 WOL was lesser in AM than CM. Oxidative status, measured by plasma reactive oxygen metabolites and thiol groups, did not differ between MS throughout the whole lactation. These results suggest that early lactation of AM primiparous cows may give rise to crucial situations: for milk production, when a low MF may impair further mammary cell proliferation; for milk quality, if an irregular MF, with prolonged milking intervals, leads to an increased milk pH with increased conversion of pl to Pl. [ABSTRACT FROM AUTHOR]