The effect of stress on udder health of dairy cows

The appropriate literature has been reviewed for the purpose of defining the phenomenon of stress in lactating dairy cattle, establishing a baseline concept of lactation stress and emphasizing the most significant aspects of the natural mammary defence mechanisms. Data on the general adaptation syndrome (GAS) make it clear that stress is essentially the rate of wear and tear of the biological system affected by a stressor either eliciting stress of the organism as a whole or partly so. Owing to the variety of stressors which may affect the dairy cow at physiological and pathological levels, a definition of stress in the broad sense is indicated. This is essential from the point of view of the anti-homeostatic effects (metabolic and immunological) of lactation stress, aggravated by anti-homeostatic effects elecited by superimposed other types of stress (e.g. heat stress). The lactating cow, as a ruminant in a state of sustained stress, requires a special profile of hormonal mediators. In high yielding cows, for example, acute and sustained heat stress promotes increased activities of prolactin, progesterone and catecholamines. Compared with the mainly glycogenic/glycogenolytic metablolism of non-ruminant mammals, the lipogenic/lipolytic and glycogenic/glycogenolytic metabolism of the dairy cow depends on hormonal mediators which differ from those of the former not so much in their nature but in their magnitude and ratios. Stressors induce the development of GAS reactions in the dairy cow. These enable the cow to create and maintain homeostasis of its integrated 3 main physio-pathological systems and thus to endure the stressor(s). The cow's compensating adjustments to a stressor are therefore the effects of stress. This means that natural lactation is the effect of the lactation stress induced by the cow's progeny (i.e. the natural lactation stressor). Artificial lactation stressors (e.g. removal of milk by hand and machine) may affect the lactation stress in magnitude but not necessarily in nature. Likewise, a range of behavioural, physiological, lactational and lacteal changes related to other stressors are the effects of different types of stress. Lactation stress, like other types of stress, shows 3 stages of development, i.e., an overcompensating alarm phase (= lactogenesis), resistance phase (= galactopoiesis) and exhaustion phase (= regression). They facilitate adjustments of the cow's homeostasis from the level of involutional homeostasis (= no lactational activity) to that of lactational homeostasis. Like other tissues in a state of stress, the lactating mammary epithelium requires a greatly increased supply of glucose. This causes the glucose metabolism of the lactating cow to become so precarious that in the secretory mammary epithelium glucose is being reserved for specific key functions, such as balance of energy and electrolytes, and formation of lactose, NADPH and citrate. The secretory epithelium is therefore particularly susceptible to fluctuations of its oxydative glucose metabolism, which, in turn, enables the cow readily to control the number of secretory cells, their level of secretory activities and the integrity of the secretory epithelium. For that reason, mammary regression, unphysiological both in magnitude and timing, if stimulated in dairy cattle by stressful conditions superimposed on normal lactation stress, is of primary importance as a counter-measure to galactopoiesis, and the main predisposing factor to mastitogenic infection. Mammary regression may be considered the cow's inherent, non-specific response to stressors affecting it and/or its lactating udder. Stressful conditions, superimposed on the lactation stress, promote increased intramammary activities of adrenalin, which contribute to unphysiological mammary regression. Adrenalin also affects the bacterial trapping component, reverse pumping component and other components of the proposed 3 core systems of the natural defence mechanisms of the lactating bovine udder. This unfavourable effect of adrenalin on udder health may be further aggravated by various hormonal mediators in the plasma and milk. From the data reviewed it is evident that stress may elicit significant lactational and lacteal fluctuations jeopardize the anti-microbial efficacy of the natural defence mechanisms of the udder and increase the risk of unphysiological mammary regression and subclinical and clinical mastitogenic udder infections. It is clear therefore that stress may be of eminent importance to the 3 major determinants of bovine udder health, namely, intramammary integrity, somatic cellular defence and bacterial challenge.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Therapy of bovine mastitis : the intramammary tissue compatibility of mastitis remedies administered intracisternally to cows

Eight different mastitis remedies were administered intracisternally on a rotational basis to the 48 quarters of 12 mastitis negative cows. The resulting intramammary reactions were monitored by determining the Somatic Cell Count (SCC) and Bovine Serum Albumin (BSA) levels in milk. The reactions observed indicate that the intramammary cellular reactions frequently elicited by the local treatments in the treated and sometimes even in the untreated quarters of the treated udders are not necessarily inflammatory in nature. Evaluation of the intramammary tissue compatibility of a mastitis remedy mainly in terms of SCC values therefore seems unreliable. Moreover, it may do injustice to a product unless the SCC values are augmented by BSA or other determinations providing a more accurate indication of truly mastitic reactions. The investigation also implies that the patterns of cellular reactions related to individual mastitis remedies require further elucidation before they can be used as indications of an advantageous or disadvantageous intramammary tissue compatibility of a product. Intramammary tissue compatibility, as such, of mastitis remedies and comparable agents requires definition. It seems more expedient, however, that such a definition and the necessary standardization of mastitis remedies in terms of their intramammary tissue compatibility be attempted by the International Dairy Federation (IDF).The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The diagnosis of subclinical mastitis in lactating cows : a comparison of cytological methods and a monovalent radial immunodiffusion test

The diagnostic accuracy of conventional methods for the diagnosis of subclinical mastitis, such as the direct microscopic count (DMC) and electronic cell count (ECC) either used alone or in combination with bacteriological examinations, according to international standards, were compared with DNA determinations and a radial immunodiffusion test (MMT). The latter is based on single radial immunodiffusion of bovine serum albumin (BSA) in agarose containing anti-BSA serum. This investigation was conducted on 1 008 foremilk samples, collected via the teat canal from 179 dairy cows, plus 56 samples obtained from 14 of them by means of cisternal puncture. It is concluded that BSA concentrations in milk causing an MMT diameter ≥ 8mm are diagnostic for mastitis in lactating cows under the conditions existing in this experiment. The coefficient of variation of the MMT (14, 67%) is significantly smaller than that of the DMC (87, 78%), ECC (72,25%) and DNA content (37, 19%) respectively and lies within the 15% limit recommended for diagnostic methods. Diagnoses made by MMT, DMC and ECC over 3 successive days varied by 4,1%; 14,5% or 28,4% respectively. The reduced repeatability of the MMT resulted from genuine changes in udder health whereas 10,1% and 24,3% of variance observed for the DMC and ECC respectively were due to other factors. In comparison to the MMT, mastitis diagnosis based on international standards resulted in 43,13 ± 20, 8% false positives. These are mainly due to teat canal infections simulating mastitis. When both the MMT and international mastitis standards were used it was possible to distinguish between quarters with irrelevant and relevant teat canal infections, non-specific cellular reactions and septic or aseptic mastitis without having to resort to cisternal puncture. Staphylococcal beta toxin inoculated into the teat canal, facilitated studies on the sequence of events leading to elevated BSA levels and cellular counts in the udder. A pre-inflammatory leucocytosis, resulting from passage of small amounts of toxin into the teat cistern was shown to occur in this investigation. The diagnosis of subclinical mastitis in dry cows and within the first week post parium is as inaccurate by means of the MMT as by conventional methods.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A high performance liquid chromatographic method for the fluorimetric determination of lactose, galactose and glucose in normal and abnormal milk of cows

A high performance, liquid chromatographic, gradient method with post-column derivatization and highly sensitive fluorescence detection has been developed for the determination of reducing sugars, such as lactose, galactose and glucose, in normal and abnormal milk of cows. The method requires little sample preparation, is applicable to a fully automated HPLC system and has been found suitable for the processing of hundreds of samples. Peaks of minor constituent components of samples showed retention times identical with those of ribose, cellobiose, fucose, mannose and xylose. Further research with the HPLC technique, supplemented with modem gas chromatography and mass spectrometry, is considered necessary for elucidating the role of minor carbohydrates in the physiology and physiopathology of the bovine udder.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A high performance liquid chromatographic method for the fluorimetric determination of lactose, galactose and glucose in normal and abnormal milk of cows

A high performance, liquid chromatographic, gradient method with post-column derivatization and highly sensitive fluorescence detection has been developed for the determination of reducing sugars, such as lactose, galactose and glucose, in normal and abnormal milk of cows. The method requires little sample preparation, is applicable to a fully automated HPLC system and has been found suitable for the processing of hundreds of samples. Peaks of minor constituent components of samples showed retention times identical with those of ribose, cellobiose, fucose, mannose and xylose. Further research with the HPLC technique, supplemented with modem gas chromatography and mass spectrometry, is considered necessary for elucidating the role of minor carbohydrates in the physiology and physiopathology of the bovine udder.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Effects of ephemeral fever on milk production and reproduction of dairy cattle

The effect of ephemeral fever (EF) on the lactation, pregnancy and fertility of 19 dairy cows was studied. During the febrile reaction milk yields were reduced by an average of 58,7 ± 22 %, depending on the stage of lactation at which the infection was contracted. Ephemeral fever predisposes lactating udders to mastitogenic bacterial infections by deleteriously affecting the leucocytic udder barrier. Delayed oestrus was associated with EF in five out of 14 cows examined.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The diagnosis of bovine mastitis with particular reference to subclinical mastitis : a critical review of relevant literature

From a review of literature on bovine mastitis published between 1833 and 1973 it is concluded that although herd control has caused a shift of emphasis from the clinical to the subclinical forms, diagnostic criteria have remained basically unaltered. Concurrent with this shift, improved bacteriological and cytological techniques are more sensitive than those available at the turn of this century. The sensitivity of these methods apparently has led to great confidence in their use in the diagnosis of mastitis. This culminated recently in a definition of mastitis as well as standardization of diagnostic criteria by the International Dairy Federation (IDF) which stressed the significance of potentially pathogenic bacteria and eleva1ed somatic cell counts (threshold 5 x 10⁵ cells/ml) in aseptically sampled foremilk. The validity of these widely accepted diagnostic criteria, particularly in the case of subclinical mastitis, is based on the assumption that an increase in the sensitivity of the methods should lead to an increase in diagnostic accuracy. Consequently, one would expect to find conclusive evidence of the diagnostic significance of the criteria used by the IDF. In contrast, this review attempts to reveal a conspicuous lack of adequately controlled experimental evidence supporting the diagnostic significance of criteria laid down by the IDF. They are of particular importance when dealing with subclinical mastitis, since the demarcation between physiological and pathological changes is considerably less distinct than in acute clinical mastitis. Thus no reference to pathological alteration of the udder epithelium, the primary symptom of mastitis, could be found in the literature assessed in terms of examination of milk. Similarly, the misleading influence of teat canal infections or lesions on the diagnostic accuracy of bacteriological and/or cytological examination of milk samples, obtained by "aseptic'' withdrawal via the teat canal, is disregarded. The physiological significance of Selye’s General Adaptation Syndrome or Schalm's Leucocytic Udder Barrier as non-inflammatory causes of elevated epithelial or leucocytes counts in milk appear to have been overlooked by workers who regard the presence of somatic cells in general or leucocytes in particular as synonymous to pus in milk. Due to absence of appropriately controlled experimental data, there is also no conclusive evidence to support the diagnostic significance of the IDF criteria referring to latent udder infections. Likewise it is not possible to distinguish between clinical and subclinical mastitis in udders with chronic indurative tissue changes in the absence of clinical alterations of the milk. The above considerations do not preclude the control of certain types of mastitis by application of IDF standards. However, because such criteria may result in some 43,13 ± 20,8% false positive diagnoses, it is conceivable that losses resulting from procedures based upon inaccurate diagnoses may far outweigh those caused directly by mastitis. The criteria of the IDF could, however, be used to great advantage for the diagnosis and control of mastitis if augmented by a test capable of establishing the physiological and pathological slate of the mammary epithelium. This is possible by means of a radial immunodiffusion test based on diffusion of bovine serum albumin (BSA), present in milk. The combination of BSA and the IDF criteria permits accurate assessment of udder health and teat canal infections.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Udder health implications of premature bovine mammary regression. I. Clinical, subclinical and reducing-sugar changes in milk during 168 hours of suspended milking in mid-lactation

The investigation involved 4 mastitis-free cows, exposed to 168 h of suspended milking to induce prolonged milk stasis and premature mammary regression during mid-lactation. After 48 h the milk stasis elicited mastitis-like changes in the clinical, somatic cell count (SCC), bovine serum albumin (BSA) and beta-N-acetyl-D-glucosaminidase(NAG) characteristics of the udder secretions. Such changes in secretions from non-mastitic regressive mammary glands raise doubts about the present knowledge, definition, and diagnosis of so-called non-specific or aseptic mastitis. Determinations of fluctuating lacteal concentrations of lactose, galactose, mannose and glucose suggest that the secretory epithelium altered its metabolism and integrity in response to the intramammary perturbation by following a certain pattern of regressive adjustments which: (i) were apparently triggered during the initial24 h of perturbation by disturbed Na-K-ATPase activities, followed by a cascade of changes in ion regulation, carbohydrate metabolism and increased formation of lactic acid as a metabolic end-product; (ii) advanced in a stepwise fashion during 0-24, 24-72 and 72-168 h of perturbation from recognition response to alarm reactions and manifestation of regression respectively; (iii) showed that markedly decreased carbohydrate levels preceded major increases of the SCC, BSA and NAG values; (iv) indicated that after 72 h of milk stasis leucocytic infiltrations sharply increased the SCC to more than 500 000 per ml and accelerated the manifestation of regression. The results of this study imply that extensive premature regression of healthy, and especially, pre-irritated udders could have significant implications for the development of different types of bovine mastitis during lactation and should be further investigated.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Udder health implications of premature bovine mammary regression. II. Collateral intramammary reactions in quarters milked normally during 168-hour milk stasis in opposite quarters

This investigation has shown that collateral intramammary reactions (CIR's) occur when secretory disturbances in one quarter lead to corresponding changes in one or more of the other, unperturbed, quarters of the same udder. Compared with normal baseline values, the mean values and variations of bovine serum albumin (BSA), beta-N-acetyl-D-glucosaminidase (NAG), mannose (MAN), galactose (GAL) and glucose (GLU) showed slight increases under CIR conditions. Fluctuations of the carbohydrates preceded changes of somatic cell counts (SCC), BSA and NAG in milk. SCC and NAG showed significant negative correlations with MAN, GAL and GLU, the latter being the only parameter significantly correlated with each of the other parameters. The data suggest that the cow's stress control system responded to the milk stasis in the unmilked quarters, by initiating a form of general stress that affected the whole udder. This aggravated regressive conditions in the unmilked quarters and provoked CIR's in the normally-milked quarters. The CIR's amounted to a transient, regressive, compensatory re-adjustment of lactational homeostasis under conditions of acute general stress. CIR's similar to those investigated could also occur in close association with other local and general stressful conditions, disturb the natural defence of the udder and account for fluctuating mammary resistance to bacterial infection.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn2014mn201

Bacteriological findings regarding the hygienic safety of poultry litter intended as an ingredient of feeds for ruminants

An investigation of poultry litter intended for use in farm feeds showed that 0,37 %, 0,49 %, 0,25 %and 12,3 % of the 813 samples tested were contaminated with Clostridium spp., haemolytic Escherichia coli, Staphylococcus aureus and 21 different species of Salmonella. The findings clearly underline the hygienically dangerous nature of crude poultry litter. The practical implications of the results are briefly discussed, particularly in view of current regulations.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.am201