The effects of a sustained-release recombinant bovine somatotropin (somidobove) on udder health for a full lactation.

The lactational effect of somidobove (recombinant bST) injections on dairy cows in a full lactation was measured in 193 primiparous and 159 multiparous Holsteins. Experimental animals, distributed across six study sites, were administered a sustained-release formulation of somidobove by subcutaneous injection every 28 d beginning 36 to 49 DIM. Randomization at each site determined which of the following somidobove treatments cows received: 0 mg (control), 160 mg (primiparous only), 320 mg, 640 mg, or 960 mg (multiparous only). In addition to lactation response, cows on study were monitored for mastitis. Clinical mastitis was detected by examination of quarter foremilk at each milking. Milk from 300 of 352 cows was monitored for new IMI by routine collection and culture of duplicate quarter milk samples. Somatic cell counts were conducted on individual composite milk samples collected weekly throughout the experiment. No evidence existed of an association between somidobove administration and the incidence or duration of clinical mastitis. Furthermore, somidobove administration was not associated with an increase in new IMI or prevalence of infection by common mastitis pathogens or pathogen groups. Somatic cell counts were low in all treatment groups, but a dose-related trend was found for increased SCC in both primiparous and multiparous cows.

Effect of early postpartum treatment with prostaglandin F2alpha on subsequent fertility in the dairy cow.

Eighty Holstein dairy cows were treated with 25 mg of prostaglandin F2alpha (PGF2alpha) on Days 14 to 16 post calving. Eighty-four herd mates served as saline controls in the double blind study. The reproductive parameters used to measure fertility were mean days to first service on all cows and mean days open, first service conception rates and services per pregnancy on cows that became pregnant. Mean days to first service was similar in both groups (71.8 +/- 27, treated; 68.5 +/- 28.6, controls; P = 0.5352). The mean days open was 98.6 +/- 52.0 d for treated cows compared to 118.8 +/- 71.2 d for controls (P = 0.0680). First service pregnancy rates (treated, 41.3%; control, 35.7%) were not significantly different (P = 0.0630); however, the mean services per pregnancy (treated, 1.64; control, 2.33) were significantly (P = 0.0021) improved in the treated group. Ten cows in the treated group and twelve cows in the control group were diagnosed as having retained fetal membranes and/or metritis. For treated and control cows mean days to first service were 82.2 +/- 34.8 d and 82.8 +/- 58.7 d (P = 0.5652). Days open were 97.0 +/- 32.5 d and 133.4 +/-58.4 d (P = 0.3636); services per conception were 1.83 and 2.50 (P = 0.3178), respectively. In all treated cows reproductive parameters were similar whether cows had high serum progesterone ( > 1 ng/ml) or low serum progesterone ( < 1 ng/ml) on the treatment day. This study suggests that early postpartum treatment of lactating dairy cows with prostaglandin produces an improvement in fertility.

Insulin and growth hormone responses to glucose infusion in mature and first-lactation dairy cows.

Five mature Holstein cows and 6 first-lactation Holstein cows were administered 100 mg of glucose/kg of body weight, IV, over a 20-minute period on postpartum day 30. A series (preinfusion, glucose infusion, and postinfusion) of blood samples was collected at -15, -10, -5, 5, 10, 15, 20, 30, 45, 60, 75, 90, 105, and 120 minutes from the start of the infusion. Serum was obtained and was assayed for glucose, immunoreactive insulin (IRI), growth hormone (GH), and free fatty acid concentrations. Baseline glucose and free fatty acid concentrations were similar in cattle of both groups throughout the sample collection period. Both groups of cattle disposed of the infused glucose in a similar manner. The first-lactation cows secreted significantly (P less than 0.0001) more IRI to utilize the glucose load than did the mature cows, 71 +/- 13 microU/ml vs 38 +/- 7 microU/ml, respectively (mean +/- SEM). Preinfusion and glucose infusion GH concentrations were similar in cattle of both groups. In the postinfusion period, GH values were significantly (P less than 0.0002) higher in the first-lactation cows (8.7 +/- 1.8 ng/ml) than in the mature cows (5.8 +/- 1.6 ng/ml). Compared with that in the mature cows, the higher IRI concentration required by the first-lactation cows to utilize approximately the same glucose load suggested that first-lactation cows were insulin resistant. The increased insulin response to increased glucose concentration may be one reason first-lactation cows produce less milk than do mature cows. Other factors, such as variation in the ability of the mammary gland to synthesize milk cannot be excluded.

Effect of propionate infusion on plasma glucagon, insulin and growth hormone concentrations in lactating dairy cows.

Altered concentrations of metabolic hormones have been suggested as important mediators of energy partitioning during early lactation. This study was initiated to determine the effects of propionate (1.0 mmol/kg body weight) infusion on plasma concentrations of glucagon, insulin, growth hormone, propionate and glucose at 14 days ante-partum (AP) and days 5 and 30 postpartum (PP). No differences were seen in propionate concentrations between sampling days. Glucose concentrations were elevated following propionate infusion in pregnant cows but were not elevated in the PP cows. Insulin responses to propionate infusion did not differ between days while the glucagon response was blunted at day 5 PP. Basal glucagon concentrations were elevated between days 5 and 30 PP, insulin concentrations were unchanged between days, while the molar insulin/glucagon ratio was decreased during early lactation. Basal growth hormone (GH) concentrations were elevated between day 14 AP and day 30 PP. GH responsiveness to declining propionate concentrations was greatest at day 5 PP. These data further suggest a role for glucagon as well as GH in nutrient partitioning during early lactation.

Bacillus stearothermophilus disk assay detection of penicillin in milk of dairy cows after postestrual intrauterine infusion.

Penicillin concentrations were quantitated in milk from cows after intrauterine infusions of various amounts of penicillin. Six healthy lactating Holsteins were assigned to 3 treatment groups in a complete randomized block design. Postestrual (12 to 48 hours) intrauterine infusions of potassium penicillin G in sterile diluent were given at 1 of 3 dosage levels: 2 X 10(6) IU (group I), 1.5 X 10(6) IU (group II), or 1 X 10(6) IU (group III). Milk samples were collected from 0 to 72 hours after infusion and were frozen until assayed for detectable antibiotic residues by the Bacillus stearothermophilus plate disk test. Intrauterine infusion of 1, 1.5, or 2 million IU caused detectable penicillin residues (greater than or equal to 5 mIU/ml) within 12 hours after infusion in milk from 15 of 18 cows. After 12 hours, no samples were positive in groups II or III and only 3 of 30 samples representing 2 of 6 cows were positive in group I. Using the B stearothermophilus plate disk test, a cow given 1 to 2 million IU of potassium penicillin G intrauterine will have detectable amounts of antibiotics in the milk within 12 hours. It is unlikely that herd composite milk samples would contain detectable concentrations of antibiotics unless a large percentage of the herd was infused or unless massive doses were administered to individual cows.

Selection and fusion of auxotrophic protoplasts of Candida albicans.

Auxotrophic mutants of C. albicans obtained by the method described by Henson and McClary (1979) were conditioned in a tris buffered EDTA-dithiothreitol solution then converted to protoplasts by suspension in osmotically stabilized buffer containing beta-glucuronidase. Complementary protoplasts were mixed in an osmotically stabilized polyethylene glycol solution and at appropriate times were plated respectively in osmotically stabilized minimal and complete agar media. From colony counts resulting from growth on the respective media, the proportion of fused complementary protoplasts (prototrophic colonies) to the total viable number of colony forming units was determined. Stability tests of selected colonies from the minimal and complete agar revealed multiple revertants, but the numbers declined to low frequencies upon repeated selective plating and isolation. Acridine orange staining of cultures thus stabilized revealed various sizes of cells with their numbers of nuclei (DNA-staining regions) varying from one to five, such that it was not determined whether the prototrophic cultures were monokaryons, heterokaryons or a mixture of the two.

Growth inhibition of Candida albicans by folate pathway inhibitors. Their potential in the selection of auxotrophs.

Growth studies were conducted on C. albicans in a glucose - salts - biotin (GSB) medium in the presence of folate inhibitors. Sulfanilamide inhibited growth which was restored by PABA or tetrahydrofolate (THF). Aminopterin inhibited growth to about the same level as did sulfanilamide, but this inhibition was not reversed with PABA nor THF, singly or in combination. Inhibition by combined sulfanilamide and aminopterin was synergistic, reducing growth by more than 90% for 48 h. The sulfanilamide component of the combined inhibition was reversed by PABA or THF to the level of that of aminopterin alone. Cytochrome synthesis was not affected by the inhibitors, but marked increases occurred in alpha-ketoglutarate, malate, isocitrate, and pyruvate dehydrogenases, especially in the presence of both inhibitors. The pyrimidines in combination with sulfanilamide were as inhibitory as was the combination of aminopterin and sulfanilamide, but they had no effect when added alone or in combination with aminopterin. Unlike the pyrimidines, the purines stimulated about a 50% recovery from inhibition by either of the inhibitors. Growth inhibition by combined sulfanilamide and aminopterin was overcome by about 50% by the addition of the THF-mediated end-produits: deoxythymidylate, adenine, histidine and methionine. The use of GSB medium containing adenine, histidine, methionine and the folate inhibitors but without deoxythymidylate resulted in thymineless death of prototrophic cells providing a method for the selection of auxotrophic mutants.

The role of metabolic energy in the lethal action of basic proteins on Candida albicans.

Comparative studies were made on the destructive effects of certain basic proteins on a strain of Candida albicans and two of its respiration-impaired mutants. Both by direct plate counts of survivors and by quantitative ultraviolet spectrophotometric analyses of released cellular constituents, the respiration-impaired mutants were less vulnerable to the destructive actions of the basic proteins than were ordinary wild-type cells. The lethal incidence and the ultraviolet absorbing cellular substances released from wild-type cells by the proteins were markedly decreased in the presence of the oxidative phosphorylation uncouplers sodium azide, 2,4-dinitrophenol, and salicylanide and approximately equal to the effects produced on an oxidative phosphorylation mutant not treated with the uncouplers. The heightened resistance of a culture through mutational or chemical impairment of its respiratory system suggests a role of metabolic energy in the destructive action of various basic proteins on yeast cells.

An alternate respiratory pathway in Candida albicans.

Usual concentrations of antimycin A, rotenone and EDTA, individually or in combination, reduced aerobic growth rate and cell yield of Candida albicans to about half its normal level and to about the levels of previously-described acetate-negative, cytochrome-complete and aa3-deficient variants which were little affected by the inhibitors. Anaerobic conditions (not affected by antimycin A) reduced growth rate and cell yield of all cultures-including that of a nonrespiring aa3, b-deficient mutant-to low, equal levels. Antimycin A but not rotenone prevented growth of the normal strain on ethanol medium. Cyanide and antimycin A blocked most of the respiration of the normal strain and cytochrome-complete variant, but did not affect that of the cytochrome aa3-deficient mutant. Rotenone and EDTA did not affect respiration of any of the cultures. SHAM blocked cyanide-and antimycin A-insensitive respiration and prolonged the lag phases of the three respiring cultures, especially in the presence of antimycin A, but alone increased oxygen-uptake rate of the cytochrome-complete cultures while curtailing that of the cytochrome aa3-deficient mutant. Resting cells, especially wild-type, grown in medium containing antimycin A exhibited lowered oxygen-uptake rate, which was increased upon the addition of cyanide or antimycin A. Antimycin A stimulated, but cyanide inhibited, respiration of cytochrome-complete cultures grown in the presence of rotenone but did not affect that of the cytochrome aa3-deficient mutant. SHAM inhibited respiration of all antimycin A- or rotenone-grown cultures. The high rate of respiration of C. albicans in the presence of inhibitors for three sites of electron transport in the conventional oxidative pathway, the inhibition of this respiration by SHAM and its loss by the absence of cytochrome b, indicate an alternate oxidative pathway in this organism which crosses the conventional one at cytochrome b.

Growth, respiration and cytology of acetate-negative mutants of Candida albicans.

A number of acriflavine-induced mutants of Candida albicans, characterized by their inability to grow on acetate as a source of energy, were screened for their cytochrome absorption spectra. Three mutants with different spectra, along with their parent, were selected for comparative studies of their growth, respiratory activities and cellular structure. The spectrum of one of the mutants was the same as that of the wild-type, but the growth rate and yield of cells on glucose medium were only about 60% of the wild-type's; those of a second mutant deficient in cytochromes aa3 were 50%, and those of a third mutant deficient in cytochromes aa3 and b were less than 5% of those of the wild-type. The cytochrome-complete mutant and the wild-type showed respiratory activity both on glucose and ethanol well above the endogenous, the cytochrome aa3-deficient mutant showed only endogenous respiration, and the cytochrome aa3, b-deficient mutant no respiration at all. Electron microscopy of the wild-type cells revealed discrete, regular ovoidal, cristate mitochondria spaced near the periphery of the protoplasm; the cytochrome-complete mutant showed an abundance of large, cristate, but morphologically irregular mitochondria; the cytochrome aa3-deficient mutant had fewer but still large, cristate, somewhat irregular mitochondria; and the cytochrome aa3, b-deficient mutant only a few simple vesicles without discernible cristae.