Some physiological and biochemical methods for acute and chronic stress evaluationin dairy cows

Stress factors are so numerous and so diverse in their strength and duration that the consequences on animal welfare can be quite varied. The first important distinction concerns the characterization of acute and chronic stress conditions. Acute stress is a short-lived negative situation that allows a quick and quite complete recovery of the physiological balance (adaptation), while chronic stress is a long lasting condition from which the subject cannot fully recover (maladaptation). In the latter case, the direct effects of the stress factors (heat, low energy, anxiety, suffering etc.), as well as the indirect ones (changes occurring at endocrinological, immune system or function level) can be responsible for pre-pathological or pathological consequences which reduce animal welfare. To evaluate the possible chronic stress conditions in single animals or on a farm (in particular a farm of dairy cows), some parameters of the direct or indirect effects can be utilised. They are physiological (mainly hormone changes: cortisol, β-endorphin), behavioural (depression), biochemical (metabolites, acute phase proteins, glycated proteins etc.), as well as performance parameters (growing rate, milk yield, fertility, etc.). Special attention has been paid to the interpretation of cortisol levels and to its changes after an ACTH challenge. Despite fervent efforts, well established and accepted indices of chronic stress (distress) are currently lacking; but without this objective evaluation, the assessment of animal welfare and, therefore, the optimization of the livestock production, could prove more difficult

Some new aspects of nutrition, health conditions and fertility of intensively reared dairy cows.

Speaking in terms of the general relationship between nutrition and reproduction, many different aspects are more or less involved depending on geographical areas, species, production systems, technological levels etc. There are deficiency conditions: energy, proteins, vitamins and minerals; but also some excesses (namely protein and few minerals) or toxic substances such as micotoxins or plant compounds (i.e. phyto-oestrogens). Their relevance is different in the intensive systems for better feeds and relative easiness to create appropriate diets. Nevertheless, intensification does not reduce the nutritional risks for livestock reproduction for several reasons: namely, a suspected higher susceptibility of high genetic merit cows to the usual stresses. There is also a new risk: metabolic stress (e.g. negative energy balance). The latter is particularly relevant when early lactation and new pregnancy are close (as in dairy cows), however, of great importance are also oxidative stress and disease stress (pro-inflammatory cytokines). In dairy cows, inflammatory phenomena around calving - when an immune response occurs in spite of clinical symptoms are missing - are significantly related to a lower pregnancy rate. A possible explanation can be seen in the pro-inflammatory cytokines, which modify liver synthesis and seem to impair energy balance thereby reducing feed intake and increasing energy expenditure. This suggests that in order to improve fertility not only better feeding mecahnisms, but any husbandry tool that can reduce diseases and health disorders are needed

Plasma cortisol variations in dairy cows after some usual or unusual manipulations

The increase of blood cortisol is a common consequence of the acute stress; this has generally positive effects, despite not completely understood (Sapolsky et al. 2000). However, at least in human beings under chronic stress, the hypothalamic-pituitary-adrenal system – responsible of cortisol release – is deregulated, resulting in pathophysiological changes, which may develop into various types of disorders (Tafet and Bernardini, 2003)

Change of digesta passage rate in dairy cows after different acute stress situations

Six dairy cows received 3 treatments after morning meal, in a double Latin square design. Treatments were ACTH challenge (SYN), hoof trimming (TRIM) and saline (CTR). Measurements included: plasma cortisol and metabolic profile during the 24 h after treatments; the rate of digesta passage, faecal dry matter and pH. Both acute stress situations vs CTR caused a rapid and similar rise in plasma cortisol (P<0.001), while plasma glucose increased only in response to TRIM. Plasma concentrations of urea and BHB were increased for several hours after both stress situations. Most importantly, the transit time of digesta was reduced with SYN and TRIM (P<0.05). Our data demonstrate a reduced forestomach motility during acute stress and confirm a possible negative linkage between stress and gut functions, perhaps independent of diet composition. The mechanism seems linked to increased ACTH or cortisol rather than corticotrophin-releasing factor

Anti-inflammatory treatments in calving dairy cows: effects on haematological and metabolic profiles

High yielding dairy cows are particularly vulnerable during the transition period to any event able to stimulate immune system. In contrast, response to these events is easily controlled in other stages of lactation

Inflammatory status and metabolic changes at dry-off in high-yield dairy cows

Our study investigates metabolic changes occurring at dry-off and the contribution of milk yield (MY) in such alterations. Thirteen Holsteins were dried off at 55 days from expected calving day (assumed as 0 days from dry-off, DFD) and divided in two groups according to their average daily MY in the last week of lactation, assuming a cut-off of 15 kg·d−1: low MY (7 cows) and high MY (6 cows). From −7 to 34 DFD dry matter intake (DMI) and rumination time were measured. Blood samples were collected at −7, 2, 7, 27 and 34 DFD to assess an haematological and metabolic profile and at −7, 7 and 34 DFD to test functions of circulating white blood cell (WBC) through ex vivo challenges. Data were included in a mixed model for repeated measures assuming MY at dry-off, time and their interaction as fixed effects. After dry-off, DMI was reduced and rumination time was increased in all the animals. High MY cows had greater DMI and rumination time than low MY cows. In blood, WBC counts decreased at 7 DFD and increased the production of pro-inflammatory cytokines at 7 and 34 DFD. Plasmatic concentrations of liver enzymes indicators, positive acute phase proteins (APPs); and nitrogen species increased after dry-off. Conversely, negative APPs and antioxidant species decreased. Those alterations were more marked in high MY animals. This study suggests that dry-off decreased liver function, triggered a systemic inflammation and depleted antioxidant systems, especially in the group of cows with high MY at dry-off.HighlightsInflammation, liver dysfunctions and altered redox balance has been detected after dry-off in all the animals.Cows with highest milk yield before halting of milk removal faced the most severe metabolic challenges.Such founding indicates the management of dry-off as a key point for dairy cows health. Inflammation, liver dysfunctions and altered redox balance has been detected after dry-off in all the animals. Cows with highest milk yield before halting of milk removal faced the most severe metabolic challenges. Such founding indicates the management of dry-off as a key point for dairy cows health

Differences in liver functionality indexes in peripartal dairy cows fed rumen-protected methionine or choline are associated with performance, oxidative stress status, and plasma amino acid profiles

The liver functionality index (LFI) represents an assessment of transition cow metabolic health by measuring changes in biomarkers associated with liver plasma protein synthesis (albumin), lipoprotein synthesis (cholesterol), and heme catabolism (bilirubin). The present analysis was conducted to determine the role of peripartal rumen-protected Met or choline (CHOL) supplementation on LFI groupings, and to assess relationships with performance, inflammation, oxidative stress status, and plasma AA profiles. A cohort of 40 multiparous Holstein cows that were part of a randomized complete block design with 2 × 2 factorial arrangement of Met (Smartamine M, Adisseo NA, Alpharetta, GA) and CHOL (ReaShure, Balchem Inc., New Hampton, NY) level (with or without) were used. From -21 d to calving, cows received the same close-up diet and were assigned randomly to each treatment. From calving to 30 d, cows were on the same postpartal diet and continued to receive the same treatments until 30 d. Addition of Met was adjusted daily at 0.08% dry matter of diet and CHOL was fed at 60 g/cow per day. Liver (-10, 7, 20, and 30 d) and blood (-10, 4, 8, 20, and 30 d) samples were harvested for biomarker analyses. Cows were ranked retrospectively and assigned to low (LLFI, LFI0) and high (HLFI, LFI0) LFI groups regardless of Met or CHOL supplementation. Compared with cows in LLFI, close-up and lactation DMI, milk yield, milk fat yield, and milk protein yield were greater in HLFI cows. As expected, cows in LLFI had lower plasma cholesterol and albumin but greater bilirubin concentrations around parturition. Plasma haptoglobin concentration was also lower in HLFI cows, but plasma paraoxonase and hepatic total and reduced hepatic glutathione concentrations were greater. Although higher concentrations of His, Met, and Trp, as well as a tendency for greater Ile, were observed in HLFI cows, overall essential AA concentrations did not differ with LFI status. In contrast, overall concentrations of nonessential AA were greater in HLFI cows due to greater circulating concentrations of Ala, Asn, Gln, Pro, and Ser. Similarly, overall concentrations of total AA and total sulfur-containing compounds were greater in cows with HLFI. Feeding Met compared with CHOL led to a tendency for more cows classified as HLFI. Overall, results support the broader application of the LFI in the management of transition cows. In that context, the fact that precalving concentrations of compounds such as reduced glutathione, total sulfur-containing compounds, Met, Tau, and homocysteine differed between HLFI and LLFI independent of Met or CHOL feeding also underscores their potential for monitoring cows that might be at a greater risk of developing health problems after calving. Further studies on the applicability of these biomarkers to monitor transition success appears warranted

Effect of grain- or by-product-based concentrate fed with early- or late-harvested first-cut grass silage on dairy cow performance

This study compared the effects of a grain-based conventional concentrate (GC) and a concentrate based on agro-industrial by-products (BC), fed with grass silage harvested at early (ES) or late (LS) maturity stage, on dairy performance, CH4 and CO2 emissions, and metabolic status of dairy cows. Twenty lactating Nordic Red cows averaging 81 d in milk and 31.9 kg of milk/d pre-trial were assigned to a replicated 4 × 4 Latin square design. Dietary treatments were in a 2 × 2 factorial arrangement. The silages were harvested 2 wk apart from the same primary growth grass ley. The GC was made from oats, barley and wheat, and soybean meal, whereas the BC contained sugar beet pulp, wheat bran, canola meal, distillers dried grains, palm kernel expeller, and molasses. The diets were fed ad libitum as total mixed rations and were formulated from 661 g/kg of silage, 326 g/kg of concentrate, and 13 g/kg of minerals on a dry matter basis. The BC supplied the cows with less energy. Despite this, milk yield and composition were unaffected by concentrate type, except that milk protein was 0.7 g/kg lower in cows fed BC than in those fed GC. These results were accompanied by a 44 g/kg decrease in total-tract digestibility of crude protein and a 54 g/kg increase in neutral detergent fiber digestibility for cows fed BC. Cows fed ES on average consumed 2 kg/d more dry matter and yielded 3.5 kg/d more milk, 149 g/d more protein, and 141 g/d more fat than cows fed LS. There were few interaction effects between concentrate and silage sources on daily intake and dairy performance. However, edible feed conversion ratio (human-edible output in animal/potentially human-edible feed) showed greater improvements with ES than LS when replacing GC with BC. Feeding diets with late-cut silage generally reduced digestibility and energy utilization efficiency, but improved N utilization efficiency. Feeding LS also led to greater CH4 yield and CH4/CO2 ratio, and higher plasma concentration of nonesterified fatty acids. Plasma parameters reflecting energy metabolism and inflammation were all within the normal ranges, indicating that the cows were in good health during the experiment. In conclusion, a conventional concentrate can be replaced by agro-industrial by-products without compromising production in early lactation dairy cows. However, silage maturity has a stronger effect on the production traits of dairy cows than type of concentrate

Pro-Inflammatory Cytokine Profile in Dairy Cows: Consequences for New Lactation

To verify the potential relevance of proinflammatory cytokine (PIC) with periparturient health problems and performances, the changes of plasma interleukin-1beta (IL-1β) and interleukin-6 (IL-6) have been investigated in 21 Holstein-Friesian cows from 35 d before to 28 d after parturition. The overall PIC concentration was higher during late pregnancy compared to the first month of lactation, but showed a high variability among the cows. Therefore, cows were retrospectively divided in 3 groups according to the values of area under the concentration curve of IL- 1β concentrations from -35 d before to the day of parturition and designated as up (UPIL1), intermediate (INIL1) and low (LOIL1) IL-1β group. The concentrations of IL-6 and to some extent the concentrations of albumin and reactive oxygen metabolites (ROMs) were well related to the grouping based on IL-1β concentrations. After calving the UPIL1 cows showed a more severe acute phase reaction (APR), based on the marked increase of haptoglobin and the lower plasma albumin concentrations during the first week of lactation, and the highest oxidative stress, based on the higher concentrations of ROMs. Moreover, the UPIL1 group showed higher number of mastitis, lower feed intake and milk yield compared with INIL1 and LOIL1. Our results demonstrated that cows with the highest PIC concentrations in the last month of pregnancy showed the worse health status in early lactation (clinical and subclinical problems) and a lower milk yield. Thus, these data support the utility of PIC measurement in late pregnancy as prognostic markers for a risky transition period

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 rumen-protected 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 non-esterified 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<0.09). 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