Production of exfoliative toxin A by Staphylococcus aureus isolated from mastitic cow's milk and farm bulk milk

The production of exfoliative toxins A and B (ETA and ETB) by Staphylococcus aureus isolated from mastitic cow's milk and farm bulk milk was examined by the reverse passive latex agglutination method (RPLA). ETA was detected in 2 (1.2%) of 162 isolates from mastitic cow's milk and in 1 (0.6%) of 166 isolates from farm bulk milk. RPLA titers of these isolates were much lower than in human isolates. No ETB was detected in any of the isolates tested. These ETA-positive isolates belonged to bovine ecovar. They were non-typable using the international phage set for human strains. When these ETA-positive isolates were subcutaneously inoculated into neonatal mice, general exfoliation of the epidermis accompanied by the so-called Nikolsky sign was not recognized. By the immunoblotting and PCR methods, however, ETA and eta gene were recognized in the ETA-positive isolates from mastitic cow's milk and farm bulk milk. These data suggest that ETA is also produced by bovine isolates of S. aureus, but in smaller quantities.     

Production of toxic shock syndrome toxin by Staphylococcus aureus isolated from mastitic cow''s milk and farm bulk milk

The renal secretion of carbenicillin (CBPC) was studied in rats. The results obtained in the in vivo study indicated very poor renal secretion of CBPC in rats, which was entirely different from those observed in humans and rabbits. In humans and rabbits, significant and stereoselective renal secretion of CBPC was observed in vivo. In order to verify the poor renal secretion of CBPC in rats, the transport characteristics of the organic anion transporters were studied in vitro using basolateral and brush border membrane vesicles. Transport of p-aminohippuric acid (PAH) into the basolateral membrane vesicles (BLMVs) was inhibited by CBPC, indicating that the organic anion transporter located at the BLM may have affinity to CBPC. In contrast, the transport of PAH into the brush border membrane vesicles (BBMVs) was not inhibited by CBPC, suggesting that the organic anion transporter located at the BBM may not have affinity to CBPC. Similar results were obtained for sulbenicillin (SBPC). Since CBPC and SBPC exist as di-anions at physiological pH, the organic anion transporter located at the rat renal BBM may not exhibit affinity to water-soluble di-anions, which in turn will result in poor renal secretion of these compounds.     

Method for computing the milk losses from sterility in cows

An attempt was made to work out a method and establish the indices in calculating the losses of milk due to sterility in cows, along with recording the level of productivity and the duration of the period of sterility. The differences were established between: 1. The size of the average daily milk yield per normative day (a day of the period between calvings of 365 days) and that per day of the actual period between calvings. 2. The average daily milk yield per normative day and that per day of the period of sterility. The milk losses calculated in both ways gave almost comparable results. It is , therefore, suggested when calculating the losses due to sterility to use the established indices of milk losses per sterility day (Table 2) at a varying milkiness of the cows and a varying length of the period between calvings, resp., the period of sterility.     

Excretion of levamisole in milk from cows treated with various formulations

The rate of disappearance of levamisole in milk from cows given levamisole hydrochloride drench, levamisole resinate in feed pellets, levamisole hydrochloride boluses, or levamisole phosphate injectable was determined. Each formulation was given as a single treatment to each of five cows at a rate equivalent to 8 mg of levamisole hydrochloride/kg of body weight. Levamisole hydrochloride residues in milk averaged .50, .55, .58, and .32 ppm at 12 hr after the administration of levamisole drench, feed, bolus, and injectable formulations. Levamisole hydrochloride residues were below .01 ppm in milk at 48 h after drench treatment and at 60 h after treatment with other three formulations. Toxicity symptoms were not observed in any cows following treatment.     

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences--but also due to structural-variation factors such as type of pathogen, animal and production level--estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.     

Effect of tuberculosis on milk production in dairy cows

A survey of Isospora suis performed in 177 faecal samples from 30 swine farms detected thin wall type I. suis oocysts in seven samples. This type of oocyst measuring 23.9 by 20.7 microns had a retracted thin wall similar to that of the genus Sarcocystis. This type of oocysts, isolated from four different faecal samples, was inoculated in four-five-days-old piglets free of contamination in order to verify the life cycle and pathogenicity of the species. The pigs were kept in individual metal cages and fed with cow milk. Daily faecal collections and examinations were performed until the 21st day after infection. MacMaster and Sheather's methods were used for oocyst counting and identification. Infected piglets produced yellowish-pasty diarrhoea with slight dehydration. The prepatent and patent periods were respectively from 6 to 9 and 3 to 10 days after infection. Oocyst elimination was interrupted on the 10th and 11th days after infection with biphasic cycles. Thin and thick wall oocysts were detected in the same faecal samples. Thin walls were not observed in unsporulated oocytes. The observations suggest that this type of oocysts could appear in specific strains which occur in the later stages of their development. These oocysts seem to be responsible for clinical and pathogenic signs of neonatal isosporosis in pigs.     

Interactions of tallow and hay particle size on yield and composition of milk from lactating Holstein cows

An 18-wk lactation study was conducted to determine whether the effects of tallow on the lactation performance of dairy cows were influenced by particle size of hay in the ration. A total mixed ration containing 50% concentrate, 25% corn silage, and 25% alfalfa hay (dry matter basis) was fed to Holstein cows. Four total mixed rations were developed based on differences in the percentage of tallow in the concentrate and particle size of alfalfa hay: 1) 0% tallow, long-cut hay; 2) 0% tallow, short-cut hay; 3) 5% tallow, long-cut hay; and 4) 5% tallow, short-cut hay. Ration had no effect on dry matter intake, body weight gain or change in body condition score. Tallow increased milk and milk protein yields but reduced milk protein concentration. However, the effects of tallow on milk and milk protein yields were the same, regardless of hay length in the ration. A tendency for an interaction of tallow and hay particle size was detected for fat-corrected milk (FCM) because tallow increased FCM more when hay was short. Ration had no effect on volatile fatty acids in ruminal samples collected via a stomach tube. In this study, the effects of tallow on milk yield and composition from Holstein cows were the same, regardless of hay particle size in the ration. The tendency for tallow to increase FCM more when hay was short suggests at least a limited role of forage particle size in the determination of how fat supplements in dairy rations affect lactation performance.     

Production and composition of milk from Jersey cows administered bovine somatotropin and fed ruminally protected amino acids

Eight multiparous and 4 primiparous Jersey cows averaging 92 d of lactation were utilized in a replicated 4 x 4 Latin square design with 28-d periods to determine responses to bovine somatotropin (bST) and ruminally protected Met and Lys when diets were fed that contained supplemental fat. Treatments were 1) control [no bST or ruminally protected amino acids (AA)], 2) control plus bST, 3) control plus ruminally protected AA, and 4) control plus bST plus ruminally protected AA. Dry matter intake was increased by bST but was unaffected by ruminally protected AA. Milk yield was increased by bST but was not altered by ruminally protected AA compared with the control diet. The bST tended to increase percentages of fat and total solids in milk and increased yields of fat, protein, 3.5% fat-corrected milk, and total solids. Ruminally protected AA increased percentages of fat, protein, and total solids in milk; however, yields of milk components were unaffected by ruminally protected AA. Body weight and body condition scores were unaffected by treatment. Concentrations of essential AA in plasma were unaffected by bST administration. Ruminally protected Met and Lys increased the concentration of Met and tended to increase the concentration of Lys in plasma. The lack of an increase in yields of milk and milk protein when ruminally protected AA were fed suggests that adequate amounts of Met and Lys were supplied by the control diet and protein reserves of the cows to meet the AA requirements for synthesis of milk and milk components.     

Decreased growth of Streptococcus uberis in milk from mammary glands of cows challenged with the same mastitis pathogen

Milk samples from mammary glands challenged with Streptococcus uberis and from unchallenged mammary glands were selected for analyses of bacterial growth, antibody response, and lactoperoxidase activity. All challenged mammary glands became infected with isolation of S. uberis and elevated somatic cell counts in milk during the first week after challenge. In vitro growth of the homologous challenge strain and a heterologous strain of S. uberis was significantly lower in milk from challenged mammary glands than in milk from control mammary glands at 3, 5, and 7 days after challenge. Removal of casein significantly reduced bacterial growth. In general, antibodies specific to S. uberis started to increase at day 3 post-challenge and were higher in milk from challenged mammary glands than in milk from control mammary glands. There was also a marked increase in total IgG in milk from challenged mammary glands. Growth of S. uberis increased following heat treatment at 56 degrees C of pooled milk or whey samples from challenged mammary glands. Growth of S. uberis correlated negatively with the specific antibody response to the bacteria (P < 0.001). Lactoperoxidase activity varied among cows and among different samples over time and did not appear to contribute to decreased growth of S. uberis. These results suggest that decreased growth of S. uberis in milk from challenged mammary glands in comparison to milk from control mammary glands could result from the interaction of antibodies with complement components.     

Feed intake and milk production in dairy cows fed whole fat soybeans]

Although the effect of hyperoxia on antioxidant enzymes is well known, the effect of subtoxic levels of hyperoxia on gamma-glutamyltransferase (gamma-GT), involved in the degradation and uptake of extracellular GSH for intracellular GSH synthesis, is unknown. The aim of the study was to investigate (1) the effects of in vitro hyperoxia on gamma-GT activity of type II cells and (2) the effects of the lazaroid U-74389G and N-acetylcysteine (NAC) on the hyperoxia-induced changes in gamma-GT and antioxidant enzyme activities. At 48 h after isolation, rat type II cells were exposed for 2 days to air, 60% O2 or 85% O2 with or without 30 microM U-74389G or 100 microM NAC. After the exposure, the cells were harvested and assayed for superoxide dismutase (SOD), glutathione peroxidase (GPx), gamma-GT activity, and GSH levels. In another series of experiments 85% O2-exposed cells, with or without U-74389G, were used for Northern blotting of gamma-GT mRNA. Exposure to 60% O2 decreased gamma-GT and GSH by -47 and -34%, respectively, while SOD and GPx activities remained unchanged. After 85% O2-exposure gamma-GT decreased by -55%, SOD and GPx increased by +55 and +87%, respectively, while GSH decreased by -35%. NAC treatment decreased gamma-GT activity by -42% in the air-exposed cells. After 60% O2, U-74389G led to significantly higher gamma-GT (+117%) and GSH (+26%) while NAC only led to higher GSH (+28%) compared to the oxygen-exposed cells not treated with NAC or U-74389G. After 85% O2 U-74389G increased gamma-GT, SOD, and GSH by +72, +58, and +68%, respectively, while NAC only increased SOD (+49%) and GSH (+26%) compared to the oxygen-exposed cells not treated with NAC or U-74389G. The 85% O2 exposure, with or without U-74389G, had no effect on gamma-GT mRNA levels. The results show that hyperoxia decreases rat type II cell gamma-GT activity in vitro. This effect was not related to an altered regulation at mRNA level and it was not associated with the hyperoxia-induced decrease in intracellular GSH, since restoration of the GSH levels by NAC did not restore gamma-GT activity. The lazaroid U-74389G with vitamin E-like properties effectively prevented the decrease in gamma-GT and GSH, so that direct inactivation of the membrane-bound gamma-GT by hyperoxia is the most likely mechanism.     

Use of clinical parameters for differentiation of gram-positive and gram-negative mastitis in dairy cows vaccinated against lipopolysaccharide core antigens

OBJECTIVE: To determine whether clinical parameters could be used to differentiate clinical mastitis (CM) caused by gram-positive bacteria from CM caused by gram-negative bacteria in dairy cows vaccinated against lipopolysaccharide core antigens. DESIGN: Case series. ANIMALS: 143 episodes of CM in 86 dairy cows in a single herd. PROCEDURE: Cows were examined at onset of CM, and 24 clinical parameters including rectal temperature, heart rate, rumen contraction rate, degree of dehydration, various udder and milk characteristics, lactation number, stage of lactation, and season of year were recorded. Milk production and milk constituent concentrations before onset of CM were obtained from Dairy Herd Improvement Association records. Values for cows with gram-negative CM were compared with values for cows with gram-positive CM. Logistic regression was used to identify important predictors of gram-negative CM. RESULTS: 64 (45%) CM episodes were caused by gram-negative bacteria and 79 (55%) were caused by gram-positive bacteria. Rumen contraction rate was significantly lower and milk protein percentage before onset of CM was significantly higher in cows with gram-negative, rather than gram-positive, CM. Logistic regression indicated that CM was more likely to have been caused by gram-negative bacteria if it developed during the summer, milk was watery, or rumen contraction rate was low. Sensitivity and specificity of the final regression model were 0.58 and 0.80, respectively. Predictive value of a positive result was 0.74 when proportion of CM episodes caused by gram-negative bacteria was assumed to be 50%. CLINICAL IMPLICATIONS: Results suggest that clinical observations do not allow accurate prediction of CM pathogens and should not be the sole criteria for deciding whether cows with CM are treated with antibiotics.     

Determination of the excretion time of oxytetracycline and lugol in milk of intrauterine treated cows

Sixteen dairy cows with chronic puerperal endometritis between 3 and 8 weeks post partum were treated with intra-uterine applied oxytetracycline (OTC) and lugol. OTC was rapidly removed from plasma and was not detectable after 48 hours. The concentration of OTC in milk did not exceed 40 micrograms/kg, and it was still detectable in milk 34 hours after treatment. The concentration of OTC in milk was always lower than the limit of 50 micrograms/kg used by milk-testing stations and the European limit (MRL) of 100 micrograms/kg. Milk from cows treated with lugol did not cause inhibition in the plate test.     

Modeling the impact of mastitis on milk production by dairy cows

Individual milk production curves of 542 cows with 722 cases of mastitis were compared with control curves drawn from healthy lactating cows. First, differences were classified into patterns of milk loss, and their distribution was analyzed among the patterns with regard to breed, season, lactation number, stage of lactation, and milk production. Then, individual milk losses were estimated and analyzed according to the same factors. In early lactation, almost 7% of mastitis cases necessitated culling or drying off. For 36% of the cases of mastitis occurring in early lactation, milk production was affected for an extended period, and the milk loss induced was 911 kg on average over the entire lactation. Fifty-two percent of the mastitis cases occurring after lactation peak was not accompanied by marked modifications of the lactation curves. For 38% of cases of mastitis occurring from mid to late lactation, milk production was affected for an extended period. When milk production was the most affected (26% of total cases), the average loss was 850 kg over the entire lactation. For cases in early or mid to late lactation, the production at mastitis onset was a determining factor of the amount and pattern of milk production loss induced. Results were applied in a simulation over two simulated groups of cows.     

Breed group effects on milk production of Brazilian crossbred dairy cows

Lactation records (n = 2362) of 1402 crossbred cows in 22 cooperating dairy herds in southeastern Brazil were evaluated. Cows were mixtures of Zebu (Gir, Guzera, and unknown) and European breeding (mostly Holstein). Lactation milk yields were expressed as total, 3050-d, or deviated 305-d yields, either adjusted or unadjusted for days in milk (DIM). Mean DIM was 280. Arithmetic means unadjusted for DIM were 1942, 1666, and 5 kg per record. Milk yields of daughters from sires of 6/8 and 7/8 European breeds were higher than yields of daughters from sires of 5/8 European breeds when data were either adjusted or unadjusted for DIM. The differences associated with breed group of sire were only slightly reduced when records were adjusted for DIM. There was no evidence of a decline in milk yield as the fraction of European breeding of the sire increased from 6/8 to 7/8. For a given breed group of sire, whether the grandsire was purebred or crossbred had no detectable effect. These results should be useful in determining strategies for crossbreeding of dairy cows in tropical areas, particularly when crossbred sires are used.     

Effect of corn silage supplementation on intake and milk production in cows grazing grass pasture

We studied the changes of frontal and parietal somatosensory evoked potentials (SEPs) in the awake state versus different stages of sleep in 10 normal adult subjects. Frontal and parietal SEP components were affected differentially as sleep stages progressed. In general, the amplitudes of frontal components, notably P22, were increased in sleep, whereas the amplitudes of parietal components were decreased in sleep. A sensitive waveform change from the awake state to sleep was present in the frontal response, where a subtle notched negativity, termed "N40," was present only in the awake state and quickly dissipated in all stages of sleep, including stage 1. The amplitude changes from the awake state to stage 3/4 sleep were neither linear nor parallel among SEP components. The most discordant changes occurred in stage 3/4. The amplitudes for the frontal N18-P22-N30 complex and parietal N20-P26-N32 complex increased from stage 2 to stage 3/4, while those for frontal N30-fP40 and parietal N32-pP40 decreased. In contrast to these divergent amplitude changes, the latencies of all components except P14 and frontal N18 showed progressive prolongation from the awake state to slow-wave sleep. The SEP waveforms and latencies in REM sleep approximated those in the awake state, although amplitudes for frontal peaks still remained slightly higher and amplitudes for parietal peaks slightly lower. We postulate that interactions of excitatory and inhibitory phenomena are responsible for the component-dependent and sleep-stage-dependent amplitude enhancement or depression in sleep.     

Effect of infused volatile fatty acids and caseinate on milk composition and coagulation in dairy cows

Milk protein secretion is changed by increasing the proportion of energy, mainly as propionic acid, or the availability of AA. Whether associative effects exist between energy nature and protein amounts is unknown. Therefore, ruminal isoenergetic infusions of low or high propionate mixtures were combined factorially with duodenal infusion of sodium caseinate or control. Four ruminally and duodenally fistulated Holstein cows were used. The diet was limited and consisted of 70% forage and 30% concentrate. Caseinate infusion increased milk yield and protein and casein contents and decreased milk fat content; curd yields and coagulation properties of milk were improved. The infusion of propionic acid caused a large increase in rumen propionate. Milk yield tended to decrease, and milk fat decreased, but protein, casein, and curd yields were unchanged; milk-coagulating properties were improved. No interaction existed between energy and protein amounts. Alteration of VFA had little effect on milk composition, but increasing the protein supply to the duodenum increased milk protein.     

Post-secretory deiodination of iodothyronines released from normal human thyroid cells in vitro

The Salmonella strains described in this paper were isolated from clinical and environmental sources in Togo (West Africa). All strains belong to subgenus I of the genus Salmonella. 1. Salmonella kodjovi 47:c:-, Supplement No. XVII (1974), isolated from stool specimen 2. Salmonella dadzie 51:1, v:e, n, x, Supplement No. XVII (1974), isolated from stool specimen 3. Salmonella mono 4, 12:1, w:1, 5, Supplement No. XVII (1975), isolated from pig droppings 4. Salmonella chincol var. s-, monophas. 6, 8:g, m:-, Supplement No. XVIII (1975), isolated from lizard intestines 5. Salmonella chicago var. i+, 28:r, i:1,5, Supplement No. XVIII (1975), isolated from stool specimen 6. Salmonella havana var. s+, 36+, 13,23:f,g,s:-, Supplement No. XVIII (1974), isolated from stool specimen 7. Salmonella elisabethville var. 15+, 3,15:r:1,7, isolated from lizard intestines.     

Fatty acid profile and physical properties of milk fat from cows fed calcium salts of fatty acids with varying unsaturation

Holstein cows (n = 24) averaging 42 d in milk were used in a randomized complete block design during a 4-wk trial. A control total mixed ration (TMR) was compared with TMR supplemented with Ca salts of fatty acids from canola oil, soybean oil, or linseed oil. The three vegetable oils were progressively more unsaturated; the dominant fatty acids were, respectively, cis-delta-9-C18:1, C18:2, and C18:3. Apparent total tract digestibility of dry matter, crude protein, ether extract, and neutral detergent fiber was higher for rations containing Ca salts than for the control ration. Milk yield increased linearly as the unsaturation of the dominant fatty acid in the Ca salts increased. Milk fat percentage was reduced when Ca salts were added to the rations. The addition of Ca salts to the ration decreased the proportions of saturated fatty acids that contained C6 to C16 and increased the proportions of C18:0, cis-delta-C18:1, and trans-delta-11-C18:1 in milk fat. Proportions of C18:2 and C18:3 increased linearly, and cis-delta-9-C18:1 decreased linearly, as the unsaturation of the dominant fatty acid in the Ca salts increased. The proportion of fat that was liquid at 5 degrees C was higher for butter from cows fed diets containing Ca salts, but the proportion of liquid fat at 20 degrees C was not affected. Calcium salts of unsaturated fatty acids added to the diets of dairy cows improved the thermal properties of milk fat.     

Influence of source and amount of dietary protein on milk yield by cows in early lactation

The purpose of this research was to examine the effects of various amounts of CP and RUP on AA flow to the small intestine and milk yield of lactating dairy cows. The first trial was a 5 x 5 Latin square design using five ruminally and duodenally cannulated multiparous cows. Diets contained chopped alfalfa hay, corn silage, high moisture corn, solvent-extracted soybean meal, and specially processed soybean meal (60.2% RUP). Soybean meal replaced high moisture corn to increase dietary CP from 14.5 to 16.5 or 18.5%, and specially processed soybean meal replaced solvent-extracted soybean meal in diets containing 16.5 or 18.5% CP to provide 6.2, 7.3, 6.7, and 8.3% RUP. Increasing dietary CP increased the flows of all AA to the duodenum. Increasing dietary RUP increased flows of Arg, His, Lys, Phe, Asp, and Glu to the duodenum. In a second trial, 36 cows were fed diets similar to those used in trial 1. Increased amounts of RUP in diets tended to increase milk yield because of improved protein status, improved intake of metabolizable energy, or both.