Simone Cogrossi

Metabolic stress and inflammatory response in high-yielding, periparturient dairy cows

Increased disease rates are commonly reported among high-yielding dairy cows in the transition period, extending from 3 weeks before to 3 weeks after calving, and characterized by the occurrence of an inflammatory response in terms of both positive and negative acute phase proteins (APP+ and APP-). To determine the above inflammatory response, the authors had developed the Liver Functionality Index (LFI), which defines the above condition on the basis of some APP- responses (albumin, cholesterol sensu stricto+bilirubin) during the first month of lactation. In this respect, low LFI values are associated to a high inflammatory response and vice versa. The relationship between LFI and inflammatory cytokine response was investigated from day -28 to day +28 with respect to calving in 12 periparturient dairy cows showing the six highest and six lowest LFI values within a cohort of 54 high-yielding dairy cows. The hypothesis being tested was that LFI and APP- on the whole could be used as readout of successful vs. non-successful adaptation to the transition period, with a strong association to disease occurrence. In fact, low LFI cows experienced many more disease cases (13 vs. 3 in high LFI Group) and related drug treatments till day +28. Interleukin-6 (IL-6) serum concentrations were always higher in low LFI cows (P<0.05 on day +28). The greater IL-6 levels were correlated with higher ceruloplasmin (APP+) and lower lysozyme serum concentrations (P<0.05 and <0.1, respectively). This latter finding was correlated with a clear role in vitro of lysozyme in a dose-dependent modulation of the inflammatory response of swine intestinal epithelial cells and bovine peripheral blood mononuclear cells. Hematological examinations showed no significant differences between the two groups under study. On the whole, our results indicate that LFI and LFI-related parameters could be used to identify cows at risk in the transition period toward an improved farm management. Also, our study indicates that disease cases in periparturient, high-yielding dairy cows are correlated with signs of accentuated IL-6 response and other markers of inflammatory phenomena. These likely start in the late lactation period or around dry-off, as suggested by our prepartal data, and proceed at much greater levels after calving.

Strategies for reduced antibiotic usage in dairy cattle farms

The need for antibiotic treatments in dairy cattle farms can be reduced by a combined intervention scheme based on: (1) timely clinical inspections, (2) the assessment of animal-based welfare parameters, and (3) the use of predictive laboratory tests. These can provide greater insight into environmental adaptation of dairy cows and define animals at risk of contracting disease. In the long-term, an improved disease control justifies the adoption of such a combined strategy. Many antibiotic treatments for chronic disease cases are often not justified with a cost/benefit analysis, because the repeated drug administration does not give rise to the expected outcome in terms of animal health. In particular, compared with untreated cases, antibiotics may not lead to greater cure rates for some forms of mastitis. Lastly, a substantial reduction of antibiotic usage in dairy farms can be achieved through the proper use of immunomodulators, aimed at increasing immunocompetence and disease resistance of cows.

Attenuation of inflammatory response phenomena in periparturient dairy cows by the administration of an ω3 rumen protected supplement containing vitamin E

The aim of this research was to study the consequences of ω3 fatty acids (FA) administration around calving on inflammatory response and on productive performances. In this period dairy cows undergo a metabolic challenge, coming with an inflammatory-like status triggering the release of pro-inflammatory mediators (e.g. eicosanoids, cytokines). Eicosanoids synthesis may be modulated by altering the ratio of their precursors (ω3 and ω6 FA). Ten cows received 22 g/d of rumenprotected ω3 FA from −21 to +21 days from calving (OPT), while 10 (CTR) received no supplement. Cows were frequently monitored for health status, body condition score (BCS), blood (metabolic, inflammatory and FA profiles), milk yield. OPT (vs CTR) showed a similar milk production, a numerically smaller BCS drop, lower postpartum levels of nonesterified fatty acids (P<0.05), β-hydroxybutyric acid (P<0.1) and creatinine (P<0.05), suggesting a milder post-calving reserves mobilization. All cows underwent an inflammatory condition around calving, but OPT showed a milder response, as suggested by lower levels of bilirubin (P<0.05), and by the higher level of Liver Functionality Index (P<0.10). Plasma concentration of ω3 FA (eicosapentaenoic and docosahexaenoic acids) increased in OPT during treatment (P<0.01 vs CTR). Since ω3 FA are the main replacers of arachidonic acid in membrane phospholipids, their increased levels in plasma of OPT cows may have cut the formation of arachidonic-derivatives (pro-inflammatory mediators), countering the beginning of the inflammation. Hence, the administration of rumen-protected ω3 FA in transition period seems to attenuate the effects of subclinical inflammations and to improve the energy balance.

Can a single rumen sample really diagnose SARA in commercial farms

The accuracy of diagnosis of subacute rumen acidosis (SARA) with a single measurement of the ruminal pH remains contradictory. To clarify this aspect, a large assessment of rumen, faecal and blood parameters was performed in several herds characterised by diets rich in non-structural carbohydrates. Rumen fluid was collected by rumenocentesis 6 h after feeding from 114 dairy cows (half 30–90 and half 150–250 days in milk) from 10 herds. In the same day, blood and faecal samples were collected and milk yield was recorded. The herds were ex-post classified as healthy (CTR n = 6) or as at risk for SARA (n = 4), based on ruminal pH. SARA versus CTR herds had lower rumen pH (5.67 vs 5.97 P < 0.01) and higher concentration of VFA, with lower acetate (P < 0.01) and higher propionate and valerate (P < 0.05) proportions. Moreover, the faecal DM was lower (P < 0.05), whereas the milk yield was higher with a lower concentration of fat (P < 0.05). At blood level, no significant differences were observed between the groups on positive acute-phase proteins, whereas SARA herds showed higher concentrations of paraoxonase and Ca and lower of cholesterol, total proteins, nitrates, Na and Zn (P < 0.01). Therefore, SARA herds did not show any evident symptom of ruminal disorder or systemic inflammation. On the contrary, these herds had a higher milk yield and a better inflammometabolic profile. These data confirm the difficulties to diagnose the SARA by a single measurement of ruminal pH in commercial herds and suggest the need of more specific indices to identify herds at risk.