Metabolic parameters and blood leukocyte profiles in cows from herds with high or low mastitis incidence.

The objective of this study was to determine whether there were differences in metabolic parameters and blood leukocyte profiles between cows in herds with high or low yearly mastitis incidence. In this study, 271 cows from 20 high yielding dairy herds were examined. According to the selection criteria, all herds had low somatic cell counts. Ten of the selected herds represented low mastitis treatment incidence (LMI) and ten herds had high mastitis treatment incidence (HMI). The farms were visited once and blood samples were taken from each cow that was in the interval from three weeks before to 15 weeks after parturition. The eosinophil count was significantly lower among cows from the HMI herds in the period from four weeks to 15 weeks after parturition. The plasma concentrations of beta-hydroxybutyrate, glucose, insulin and urea did not differ between groups, but the concentration of nonesterified fatty acids was significantly higher among HMI cows during the period three weeks after parturition. The concentration of the amino acid tryptophan in plasma was significantly lower among the HMI cows prior to parturition. Glutamine was significantly lower in cows from HMI herds during the first three weeks after parturition. Arginine was consistently lower in HMI cows, although the decrease was only significant during the period from four to fifteen weeks after parturition. The results suggest that there were differences in the metabolism and immune status between herds with high or low yearly mastitis treatment incidence indicating an increased metabolic stress in HMI cows.

The effect of the plasma glucose level on the abomasal function in dairy cows.

We have studied the effect of plasma glucose level on the abomasal outflow rate of fluid using a hyperinsulinemic glucose clamp technique in dairy cows. Four nonpregnant, nonlactating cows were subjected to one of the following treatments: hyperinsulinemic normoglycemic clamp; hyperinsulinemic hypoglycemic clamp; hyperinsulinemic hyperglycemic clamp; or, as a control, an intravenous infusion of .9% sodium chloride in a Latin square design. The cows were previously fitted with a permanent fistula in the abomasum and the outflow rate of abomasal fluid was determined using Co-EDTA as a marker assuming that the outflow followed first-order kinetics. The abomasal pH was also registered. Insulin was infused continuously through a jugular catheter at a rate of 4.8 mU. kg(-1)min(-1) for 2.5 h in the three clamp treatments. A glucose solution was infused through the catheter at a variable rate to achieve a circulating concentration, near the preinfusion glucose level (approximately 4.1 mmol/L), 2 mmol/L below the preinfusion level, and 2 mmol/L above the preinfusion level for the three hyperinsulinemic treatments, respectively. There was a significant effect of treatment on the rate of abomasal outflow (P < .001). The rate of abomasal outflow was highest for the control treatment (7.8%/min). The slowest outflow was observed in the hyperglycemic cows (3.40%/min). The hypoglycemic and normoglycemic cows showed intermediate rates (6.0%/min and 5.2%/min, respectively). The rate of outflow for the hyperglycemic cows was significantly lower than for all the other treatments (P < .01). Abomasal pH was affected by treatment (P < .05). The highest pH was observed in the hyperglycemic cows (pH 2.3). The values for the other three treatments ranged from pH 1.9 to 2.0. These results show that hyperglycemia reduced the rate of outflow and increased the pH of abomasal fluid in dairy cows. An elevated plasma glucose level thus can be considered as a potential risk factor in the pathogenesis of left-displaced abomasum.

Effects of intravenous infusion of glucose and pancreatic glucagon on abomasal function in dairy cows.

Four cows of the Swedish red and white breed fitted with a cannula in the abomasum were used in 2 experiments. In experiment I glucose (4 mg/kg bw/min) was infused intravenously for 60 min after an initial control period, without infusion, of 60 min. The turnover time of abomasal fluid was calculated using Cobalt-EDTA as fluid marker. The frequency and amplitude of the abomasal pressure changes were registered during the experiment. The plasma level of insulin and glucose was also registered during the experiment. Due to the glucose infusion plasma glucose increased with about 4 mmol/l. The elevated plasma level of glucose induced a pronounced release of insulin. The turnover time of abomasal fluid increased from 15.7 +/- 1.2 to 27.8 +/- 3.5 min (p < 0.01) during the glucose infusion. The mean amplitude of the pressure changes showed a more than twofold increase (p < 0.05) during glucose infusion as compared with the control period but there was no difference in the frequency of the changes. In experiment II there was a similar experimental set-up with the exception that pancreatic glucagon (30 pg/kg bw/min) was infused instead of glucose. The glucagon infusion induced a release of endogenous glucose which in turn increased the plasma level with about 3 mmol/l. The plasma level of insulin rose to about the same extent as during the glucose infusion in experiment 1. The turnover time of abomasal fluid was delayed from 15.4 +/- 1.7 to 34.8 +/- 1.9 min (p < 0.001). There were no significant effects of the glucagon infusion on the frequency or the amplitude of the abomasal pressure changes. The results of the present study indicate a disturbed abomasal function in cattle with hyperglycaemia. It remains to be investigated if it is a direct effect of the hyperglycaemia or if it is secondary to the elevated insulin level.

Effects of peroral alanine administration in lactating ewes with decreased availability of glucose.

The metabolic effects of a phlorizin-induced drainage of glucose were studied in six lactating ewes with or without peroral alanine drenches in a study of crossover design. Phlorizin gave rise to a small, but significant, elevation of plasma beta-hydroxybutyrate. The plasma level of alanine decreased by about 30% due to the phlorizin injections and alanine was negatively correlated to beta-hydroxybutyrate. The plasma level of free fatty acids increased due to phlorizin. Plasma insulin and glucose concentrations were not significantly affected by phlorizin while glucagon level showed a small but significant increase. Peroral alanine drenches to phlorizin-treated ewes gave rise to a transitory elevation of alanine in plasma. The plasma level of free fatty acids was about 40% lower in phlorizin-treated ewes receiving alanine and beta-hydroxybutyrate tended to be lower (P < 0.08). We suggest that beta-hydroxybutyrate, apart from its function as an oxidative fuel, might play an important role by limiting glucose oxidation and protein degradation in skeletal muscles during periods of negative energy balance in ruminants. Furthermore, it is suggested that alanine supplementation decreases lipolysis and ketogenesis in lactating ewes.

New aspects of ketone bodies in energy metabolism of dairy cows: a review.

Increased lipolysis, low insulin/glucagon ratios and malonyl-CoA concentrations are prerequisites for ketogenesis. From an aetiological viewpoint, there are two quite different types of metabolic disorders in which ketosis can occur, the hypoglycaemic-hypoinsulinaemic and the hyperglycaemic-hyperinsulinaemic type. The former, Type I, generally occurs 3-6 weeks after calving in cows whose milk secretion is so extensive that the demand for glucose exceeds the capacity for glucose production. To protect the body from hazardous protein degradation by a high rate of gluconeogenesis, this process is inhibited and the increased energy requirements are met by the elevated utilization of ketone bodies. In this strong catabolic metabolic state the plasma levels of glucose and insulin are very low, the levels of ketone bodies are high and there are small risks for fat accumulation in the liver cells. The hyperglycaemic, hyperinsulinaemic form, Type II, generally occurs earlier in lactation. An important aetiologic factor is overfeeding in the dry period, which can lead to disturbances in the hormonal adaptation of metabolism at calving with increased plasma levels of insulin and glucose and often out not always also with hyperketonaemia. If combined with stress, there may be increased lipolysis in adipose tissues, lipid synthesis and accumulation in the liver, i.e. the development of fatty liver. This hyperglycaemic form of disturbance has many similarities with the initial stage of non-insulin-dependent (Type II) diabetes in humans. It has been shown that ketone bodies inhibit protein degradation and thereby gluconeogenesis and also are able to spare glucose by inhibiting glucose utilization. They also can inhibit lipolysis and function as a regulatory safety system, replacing insulin, in situations when the activity of this hormone is low, as in Type I ketosis. Ketone bodies thus have important functions as substrates replacing glucose in many tissues and also as signal substances in the regulation of energy metabolism.

Effects of different energy levels, concentrate/forage ratios and lipid supplementation to the diet on the adaptation of the energy metabolism at calving in dairy cows.

A low level of energy (110 MJ ME) and a low concentrate/forage ratio (10/90) at calving resulted in low basal concentrations of glucose and insulin, but the cows had the capacity to increase the glucose level after glucagon injections. No signs of disturbances in the metabolic adaptation were observed. High intensity feeding (200 MJ ME and 50% concentrates) resulted in high basal serum insulin levels. The increase in the insulin concentrations after glucagon injections and the changes in insulin levels around calving varied widely between individual cows. The metabolic adaptation period was longer than in cows in the former group. An energy level of 170 MJ ME and variations of concentrate/forage ratios (5/95, 30/70 and 60/40) resulted in small differences in basal glucose and insulin concentrations and in response to glucagon injections. But the cows fed 60% concentrates showed signs of prolonged metabolic adaptation. Increased lipid concentrations in diets containing equal levels of energy and protein resulted in a fall in basal glucose and insulin levels and the metabolism seemed to be directed towards catabolism. Because of these metabolic effects, more needs to be known on fat supplementation if it is used in practical feeding. It is also necessary to take more interest in the effects of protein feeding on the periparturient metabolism.

Periparturient concentrations of insulin glucagon and ketone bodies in dairy cows fed two different levels of nutrition and varying concentrate/roughage ratios.

High producing multiparous dairy cows were fed either diets differing in energy content or diets with identical energy and protein content but differing in roughage content at the end of the dry period and beginning of lactation. Basal insulin and ketone bodies were analysed every week from 3 weeks before to 7 weeks after calving. Pancreatic glucagon was estimated 3 weeks before, 1-3 days after, and 3 weeks after calving. Before calving the feeding regimen had a very strong influence on the basal insulin level. High amounts of concentrate increased basal insulin levels until one week before calving and caused an interruption in the physiological decreasing course. After calving the insulin levels were low in all groups of cows. Before calving there were small variations in the glucagon levels, and no influence of feeding was observed. After calving there was a strong increase, especially in the cows fed the highest amounts of concentrate. Feeding high amounts of concentrate resulted in varying and in many cases increased levels of ketone bodies in plasma. Hyperketonemic cows had lower insulin and higher glucagon levels than normal cows. The influence of non-structural carbohydrates in the feed on pancreatic hormones is a cause of ketogenesis is discussed.

A comparative study of arterial and venous blood acetate concentration in cows fed different diets close to parturition.

Blood samples were collected from the coccygeal artery and a jugular vein two weeks before expected calving, one to five days after calving and three weeks after calving of cows which were fed either a high roughage or a low roughage diet from four weeks before to 14 weeks after calving. The mean venous acetate concentration ranged from about half to three-quarters of the arterial concentration. No differences were observed at any time between concentrations of acetate in either the arterial or venous blood of the cows on the different diets.

Impaired glucose tolerance and heterogeneity of insulin responses in cows with abomasal displacement.

Injections of glucagon in dairy cows resulted in a rapid and marked increase in serum insulin and also in plasma glucose. Glucagon injection appears to be a simple and useful method for testing insulin secretion and glucose release. There was a somewhat reduced insulin response 2 weeks after calving in normal cows. Cows given high intensity feeding before calving showed higher plasma glucose levels in the glucagon test 3 days post partum and showed signs of reduced sensitivity to insulin action. Cows with abomasal displacement showed impaired glucose tolerance and heterogeneity of insulin responses indicating insulin resistance and signs of Type 2 (non-insulin-dependent) diabetes mellitus.

Plasma lipids in normal cows around partus and in cows with metabolic disorders with and without fatty liver.

Free fatty acids, cholesterol and phospholipids in plasma were studied from 6 weeks before to 6 weeks after calving in 16 normal multiparous cows. The same plasma lipids were studied the day after calving in 20 normal primiparous cows. Ten of these were fed according to standards and the other 10 were overfed the last 3 weeks prepartum. The plasma lipids were also analysed in 16 cows with left displacement of the abomasum and fatty liver, and in 16 cows with ketosis with no or only slight fat infiltration of the liver. In the normal cows there was a rise in FFA-level and a reduction in cholesterol and phospholipids from 6 weeks before to the day after calving. Thereafter there was a reduction of FFA-level and rise in cholesterol and phospholipids. Increased feed intensity had no effect on plasma lipids at calving. The level of the plasma lipids in cows with fatty liver differed very much from the amounts in normal cows at corresponding time from calving. Cows with ketosis had high FFA-level but the amount of cholesterol and phospholipids differed very little from normal cows.

Epidemiological studies on Ostertagia ostertagi infections in cattle during their first, second and third summer on pasture.

The number of Ostertagia ostertagi in the abomasum of steers, that had been on pasture for one, two or three summers was determined. A total of 44 animals were examined and of these 12 had been out one summer 27 two summers, and five during three summers. During the grazing seasons plasma pepsinogen and serum albumin was determined on all the steers and on 24 heifers during their first summer on pasture. The mean number of parasites in the abomasum after one summer was 128,500 and at the end of the second summer 2,400 and after the third 800. In animals slaughtered in February after housing in October the first year the mean number was 33,300 with 29,900 arrested L4-larvae. During the first summer on pasture there was a strong rise in the plasma pepsinogen values until the beginning of August. This rise reflected the infection rate. Also after turning out the second and third summer a rise in plasma pepsinogen was noted but now with shorter duration. This rise was probably caused by liberation of arrested L4-larvae from the preceding year. The serum albumin values decreased in all animals after turning out. However, the decrease was strongest the second and third summer when the parasite number was low. This indicates that also other factors than parasites influence the serum albumin level.

Studies on the effect of treatment with anthelmintics on weight gain in calves, naturally infected with gastrointestinal nematodes.

To avoid disease outbreaks caused by gastro-intestinal nematodes different prophylactic measures are recommended. In this connection pasture hygienic achievements and anthelmintics are used. In practice it is often difficult to realize pasture hygienic steps as move the animals to parasite free areas and to avoid that they come back to the infected. In many cases the parasite control is limited to routine deworming. Our intention was to study if anthelmintic treatment without other measures had any effect on weight gain and number of eggs in faeces in calves naturally infected with Ostertagia ostertagi. The studies were done during two stable seasons 1975/76 and 1976/77 when the calves were treated two weeks after stabling, and during two grazing seasons 1976 and 1977 when the calves were treated 20 days or 15 and 20 days after turning out. In none of the trials any obvious influence on the weight gain and number of eggs was observed. The failing effect during the stable season might depend on the fact that the parasites to more than 90% were in inhibited L4-stage, and the failing effect during grazing, is surely an effect of reinfection when the calves remain on the infected pastures. As prophylactic measure anthelmintic treatment is of very little value if not the calves at the same time are protected against reinfection by moving to clean pastures.

[The effect of antibiotic supplementation on antibiotic resistance, transferable antibiotic resistance, morbidity, and growth in calves (author's transl)]. / Effekten av foderantibiotika på antibiotikaresistens, överförbar antibiotikaresistens, morbiditet och tillväxt hos mellankalv

112 calves, divided into four groups, were given milk substitutes containing tetracycline (high-dosage feed), zinc bacitracin or Lactosat (control) and concentratesw with or without zinc bacitracin (Table I). We have investigated the incidence of antibiotic resistance and transferable antibiotic resistance in E. coli strains isolated from the faces of these calves and checked the growth and state of health in the four groups. Growth was also studies in a further ten feeding series comprising a total of 258 calves. Half this number received zinc bacitracin in milk substitute, the other half were fed milk substitute containing Lactosat, instead of antibiotics (Fig. 8). Tetracycline led to a quick increase of antibiotic-resistant straing (Fig. 4--6). This increase is significant in comparison with the other groups. Significant increases of resistance were also noted to ampicillin and chloramphenicol (Fig. 7), althoug these drugs were not used. A significant increase of the transferable resistance was also observed in the group of calves given tetracycline (Fig. 7) and to 65% at about 31/2 months after the end to 38% within 12 days (Fig. 7) and to 65% at about 31/2 months after the end of tetracycline feeding (Fig. 7). A marked increase of en-bloc transfer was also noted after completion of tetracycline feeding (Fig. 2). Up to slaughter, at the age of 6 months, no better growth was obtained with zinc-bacitracin supplement than with milk substitute without antibiotics but containing Lactosat. During the milking period the results varied between the different feeding series. In some series the mean growth in the zinc-bacitracin group was better than, in some no different from, and in other s poorer than that in the Lactosat group (TableII, Fig. 8). The only demonstrable positive effect of tetracycline supplement was a tendency twwards better health during the period of administration of the drug (Table II...