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Biomedical subjects

R C Lamb

Publications and source records attributed to R C Lamb.

At least 19 recordsLinked to original sources
PubMed1991

Responses by lactating cows in commercial dairy herds to recombinant bovine somatotropin.

Cows (890) in 15 US herds were assigned randomly in equal numbers to control or bST injections (500 mg in a prolonged-release form every 14 d for 12 wk) within three stages of lactation (57 to 100, 101 to 140, and 141 to 189 d postpartum) and two parity groups (primiparous and multiparous). Yield and milk composition were monitored 1 d/wk for 16 wk including 2 wk pretreatment and 2 wk posttreatment. Increases in milk and FCM due to bST injections were less at 57 to 100 d than at 101 to 189 d postpartum (milk 3.6 vs. 5.5; FCM 3.9 vs. 6.1 kg/d per cow), and increases in milk and FCM were more for multiparous than for primiparous cows (milk 5.5 vs. 4.2; FCM 6.0 vs. 4.7 kg/d cow). Temporarily, concentration of milk fat increased and protein decreased; later, concentrations for control and injected cows were similar. Postinjection milk fat concentration decreased, but milk protein concentration increased temporarily. The net increase in milk (and FCM) varied significantly among herds from 2.9 to 7.6 kg/d per cow (mean, 4.9 kg). Responses in FCM were similar over a wide range of pretreatment yields. A great variety of feed ingredients were fed as total mixed rations, and nutrient concentrations varied greatly. The SCC were similar before, during, and after treatment, but increase in FCM of injected cows exhibited a negative correlation with pretreatment SCC. Changes in body condition score of sometribove-injected cows varied among herds (.25 to -.45) and averaged -.02 compared with .07 for controls. There was no pattern in incidence of mastitis during sometribove injections.

Animal Feed↗
PubMed1991

Evaluation of sometribove in a prolonged-release system in lactating dairy cows--production responses.

Primiparous (n = 105) and multiparous (n = 136) Holstein cows were used to evaluate efficacy of sometribove (n-methionyl bovine somatotropin, bST) in a dose titration study. Cows were fed TMR for ad libitum intake, were milked twice daily, and were allocated randomly within parity (1 vs. 2+) to treatments of 0, 250, 500, or 750 mg bST/14 d in a prolonged-release formulation. Subcutaneous injections commenced 60 +/- 3 d postpartum and continued throughout lactation. During a standardized treatment period of 252 d, treatment with increasing dosages of bST increased 3.5% FCM yield in a dose-dependent manner for both primiparous (2.5 kg/d, 10.2%; 3.5 kg/d, 14.3%; and 5.9 kg/d, 24.1%) and multiparous cows (3.1 kg/d, 12.1%; 3.9 kg/d, 15.2%; and 6.8 kg/d, 26.5%). Milk content of fat, protein, lactose, ash, Ca and P, and SCC were not affected by treatment. Over the 252-d treatment period, voluntary intake of energy was increased in bST-treated cows such that BW gain, body condition score, and net energy balance did not differ among treatment groups. Productive efficiency (milk per unit NEL intake corrected for BW change) over the treatment period was significantly increased in a dose-dependent manner for multiparous cows (4.1, 6.8, and 11.0%). Results demonstrated that bST administered in a prolonged-release formulation was efficacious in enhancing milk production and feed efficiency.

Animals↗
PubMed1988

Effect of sodium bicarbonate and magnesium oxide in an alfalfa-based total mixed ration fed to early lactating dairy cattle.

Forty-eight lactating Holstein cows were fed a total mixed ration of 57% concentrate and 43% forage (dry basis) for 12 wk postpartum. Treatments consisted of 1) no added buffers, 2) .4% MgO, 3) .8% NaHCO3, and 4) .8% NaHCO3 plus .4% MgO of the total ration DM. Body weight, DM intake, and milk yield and composition were unaffected by treatment. Gross efficiency of milk production was decreased by the addition of NaHCO3 or MgO. Buffer supplementation had no effect on ruminal volatile fatty acid concentration or blood chemistries.

Animal Feed↗
PubMed1987

Effect of mineral salts, carbachol, and pilocarpine on nutrient digestibility and ruminal characteristics in cattle.

Fifty percent concentrate diets containing 2% sodium bicarbonate, sodium chloride, or no additional mineral salts were fed at a rate of 86 g dry matter/kg body weight X 75/d to three barren Holstein cows fitted with ruminal fistulas in a 3 X 3 Latin square design. Dietary adaptation was 14 d followed by 4 d collection. Ruminal pH, liquid volume, liquid dilution rate, and particulate rate of passage were increased with dietary mineral salts. Six Holstein cows fitted with ruminal fistulas were administered .01 mg carbachol/kg body weight/d, .10 mg pilocarpine/kg body weight/d, or saline placebo via subcutaneous, osmotically controlled pumps in a replicated 3 X 3 Latin square design. Treatments were administered for a 14-d adaptation period followed by an 8-d collection period. Both carbachol and pilocarpine increased liquid dilution rate, particulate rate of passage, and percent cellulolytic bacteria, whereas liquid volume was reduced.

Animals↗
PubMed1987

Physiological and glucocorticoid response to treadmill exercise of Holstein heifers.

Effect of exercise for 8 wk prepartum on heart rate, respiration rate, rectal temperature, and serum glucocorticoid concentration was determined for nine Holstein heifers. Exercise was on a treadmill 30 min daily, 5 d/wk, for approximately 8 wk. Physiological measures were taken at rest and immediately postexercise; blood samples were taken via jugular vein cannulas at 2-h intervals 26 h preexercise, at 10-min intervals during exercise and 21.5 h postexercise, all at initiation of the experiment and again near the end of pregnancy. The three physiological measures increased during exercise at both the initiation and termination of the 8-wk exercise period. Mean serum glucocorticoids of heifers increased from 5.4 to 21.3 ng/ml during initial exercise but increased from 4.4 to 5.2 ng/ml following approximately 8 wk exercise. These glucocorticoid data mimic trends found in other species, i.e., physically fit subjects or animals trained to chronic exercise have lower glucocorticoids than sedentary or untrained subjects during intense or exhaustive exercise.

Animals↗
PubMed1987

Clinical effects of low dietary phosphorus concentrations in feed given to lactating dairy cows.

Thirty-four Holstein cows, pregnant with their second calf, were individually fed diets containing 3 concentrations of phosphorus (P): 24 cows for 12 months and 10 cows for 7.5 months of lactation. Cows were randomly allotted to the specific dietary groups 2 months before expected parturition. The 3 dietary concentrations of P were 0.24%, 0.32%, and 0.42% in diet. Cows given 0.24% P in diets produced significantly less milk than did cows in the other groups. Other clinical signs of P deficiency in the cows fed the diet with 0.24% P included loss of body weight, decreased feed consumption, and lower inorganic serum P concentration 2 to 10 weeks after parturition. There were no significant differences in the variables measured between cows given dietary P concentrations of 0.32% and 0.42%. There was no evidence of hemoglobinuria after parturition. Reproductive performance did not differ significantly, although the trend was in favor of the cows fed the diet with 0.24% P.

Animals↗
PubMed1985

A pair of five-day flaps: early division of distant pedicles after serial cross-clamping and observation with oximetry and fluorometry.

In each of 2 recent patients with distant pedicles (one a groin flap and the other a cross-leg flap), we were able to perform the final division and detachment of the flap on the fifth postoperative day. Cross-clamping was used to create intermittent periods of ischemia. The periods of ischemia were progressively increased until the time of division. Fluorometry with intravenous fluorescein played a role in deciding when to divide the flap. The patients were discharged from the hospital on the sixth and seventh days, respectively. Trimming was done on an outpatient basis.

Adult↗
PubMed1984

Microvascular gastrocnemius muscle transfer to the distal leg using saphenous vein grafts.

The gastrocnemius muscle has been transferred to the distal leg by lengthening its vascular pedicle with interposition saphenous vein grafts. This procedure is presented as an alternative to free-flap transfers requiring vein grafts to the proximal leg. By increasing the arc of rotation of the gastrocnemius muscle with vein grafts, the full dimensions of the muscle can be used to cover large prepatellar, suprapatellar, and distal leg defects.

Adolescent↗
PubMed1983

Fournier's gangrene of the scrotum. A poorly defined syndrome or a misnomer?

Fournier's gangrene is defined classically as a fulminant, rapidly spreading infection of the scrotum that also involves the perineum, penis, and abdominal wall. The pathologic findings are described as synergistic gangrene secondary to a polymicrobial flora with a poorly defined portal of entry. In our experience with 12 cases, the portal of entry was well defined and the causative organisms were those typically found in the lower bowel. Portals of entry were perirectal abscesses in five patients, urethral infections in three, and surgical procedures in four patients. All patients required aggressive surgical debridement, broad-spectrum antibiotics, and adjunctive measures. The fact that four patients died in spite of aggressive treatment demonstrates the lethal nature of this disease. This study suggests that this syndrome is no longer "idiopathic" but is primarily a necrotizing cellulitis of the perineum with subsequent involvement of the genitalia and surrounding tissues.

Anti-Bacterial Agents↗
PubMed1983

Gas gangrene.

Gas gangrene is not a disease of the past. Despite improved awareness, earlier care of trauma victims, new antibiotics, and advanced monitoring techniques, histotoxic clostridia continue to cause loss of life and limb. A 20-year literature review on gas gangrene (Part I) indicates that a combined therapy approach with early recognition, surgical intervention, appropriate antibiotics, and hyperbaric oxygen (HBO) provides optimal care. Part II, a 15-year clinical experience, appears to be the largest English-language series reported using the combined therapy of antibiotics, surgery, and hyperbaric oxygen. One hundred thirty-nine patients (95 males and 44 females), average age, 38 years, were admitted with clostridial myonecrosis. Sixty-seven were in shock at admission and the 27 deaths occurred in this group. One hundred twelve patients (81%) survived the infection. There was a 5% mortality in post-traumatic extremity clostridial myonecrosis. Age and concurrent disease increased the mortality rate, as did delay from time of diagnosis to aggressive combined treatment.

Adolescent↗
PubMed1982

Attaining and measuring physical fitness in dairy cattle.

Research with dairy cows was to determine whether dairy cows in confinement are in poor physical condition, if programmed exercise improves physical fitness, and which physiological measures are most useful indicators of physical fitness. If maintenance of physiologic homeostasis when an animal is under a work load is a valid criterion of physical fitness, dairy cows in confinement are in poor physical condition, and physical fitness can be improved by programmed exercise. Walking cows at 4 km/h for a distance of 8 km daily for 5 days per wk for 8 wk prepartum improved their physical fitness. Useful hemic indicators of improved fitness were less increase in erythrocyte numbers and hemoglobin concentration and less decrease in oxygen tension, carbon dioxide, carbonic acid contents, and base excess than in poorly conditioned cattle under work load. Venous blood was satisfactory for these measurements. Also valued were heart and respiratory rates, except these rates being sensitive to extraneous disturbances may be less reliable.

Animals↗
PubMed1981

Forced walking prepartum for dairy cows of different ages.

Fifty-three 2-yr-old Holstein heifers and 63 cows from 3 to 7 yr old were exercised 5 days/wk for 8 wk before calving. Three treatments were: 1) control (no forced exercise); 2) walk 1.6 km/day; and 3) walk 8.0 km/day. Exercise was at 4.0 km/h in a circular lane with a motor-driven gate. Daily feed intake and weekly body weights were recorded during the prepartum period and 50 days postpartum. Daily milk production and semimonthly milk composition were recorded for the complete lactation. Exercise did not affect feed intake during the prepartum period. Weight gain was reduced during the dry period, more for older than for young cows, and particularly less gain for the longer distance. There was no benefit to production or feed efficiency from exercise for any age of cows. Production of protein and solids not fat was higher for combined ages of cows on the shorter than the longer distance. Protein percentage in milk for the lactation was higher for exercised than for control cows; solids-not-fat percentage in milk was higher for exercise for shorter than for longer distance; and fat percentage in milk was not affected by exercise. Number of services per conception and number of days open were less for exercised cows.

Age Factors↗
PubMed1978

Effect of exercise on glucocorticoids and other cellular components of blood.

The effect of exercise during the dry period on glucocorticoids, packed cell volume, hemoglobin concentration, total leucocytes, and differential leucocyte count was examined with 87 Holstein cows. Cows were divided randomly into groups: 1) control, 2) 3.2 km at 3.5 km/h, 3) 9.6 km at 3.5 km/h, and 4) 3.2 km at 5.5 km/h. Sampling for blood analysis was at weekly intervals preexercise and immediately postexercise. Both glucocorticoids and hemoglobin concentrations were increased by exercise. Correlations between glucocorticoids and most other traits were practically zero. No eosinopenia was noted with increasing glucocorticoids. Lymphocyte numbers were correlated negatively with all traits measured. Glucocorticoid concentration increased from pre- to postexercise with both distance and speed. Although glucocorticoid concentration varied among cows, neither day sampled, days dry, weight, nor age affected glucocorticoids. Increased hemoglobin of postexercise cows could not be attributed to speed or distance exercised. Traits measured in this study, other than glucocorticoid concentration, are ineffective in evaluating response to increased exercise.

Animals↗
PubMed1977

Effects of dominance rank changes, age, and body weight on plasma corticoids of mature dairy cattle.

The purpose was to determine whether forced change in dominance rank affected total corticoids of plasma of dairy cattle. Nineteen cows in late lactation were assigned randomly to one of two lots. Restriction of manger space enhanced observations of dominance rank during feeding for three 1-h periods per wk over 6 wk. After 3 wk, a group of the five highest ranking cows from each lot were combined into a new aggressive lot; two groups of subordinate cows formed a docile lot. Blood samples were from tail vein, and concentrations of total corticoids were determined by competitive protein binding. Changes of dominance rank varied from zero to eight places in the 10-cow assemblage after new lots were formed. Body weight was the most significant variable affecting dominance rank. There was no discernable relationship between total corticoids and dominance rank, body weight, or age. The pattern of variation of total corticoids was similar for all groups during the first 3-wk period, but in the second period docile and aggressive groups had dissimilar patterns. Interaction of group by week for total corticoids was significant; however, a cause and effect relationship could not be established. Total corticoids did not appear to be a valid or useful determinant of social stress.

Adrenal Cortex Hormones↗
PubMed1977

Facility for exercising dairy cows.

That dairy cows housed in confinement might benefit if they were exercised during the dry period prompted development of a facility for exercising dairy cows. Two methhods of the exerciser, which consist of a circular lane and a driving mechanism powered by a variable speed electric motor, are described. A speed of 3.5 k, per h provides a steady but comfortable pace for pregnant dairy cows and heifers. Many animals refused to go at speeds greater than 5.5 km per h.

Animals↗
PubMed1975

Genetic and environmental effects on serum cholesterol of dairy cattle of various ages.

Serum cholesterol of dairy cattle, particularly when measured on animals of the same approximate age, is a heritable trait. Heritabilities were .50 for first lactation cows and .19 for heifers from 2 to 22 mo of age. Serum cholesterol increases with increasing age. Serum cholesterol was 192.8 mg/100 ml in cows and 121.4 mg/100 ml in heifers. Serum cholesterol was relatively low at the onset of lactation, increased at mid-lactation, and leveled off or decreased in late lactation. Month of calving, year of sampling, and ration did not influence serum cholesterol of first lactation cows. However, variation in both month and year of sampling was significant for heifers.

Age Factors↗
PubMed1975

Genetic relationship between birth weight and adult weight in Holsteins.

Records of body weight for 1026 Holstein females from two herds included birth weight and all available subsequent calving weights for the first six parities. Birth weight differed between herds and between sires within herds. Years also differed; however, partial nesting of sires within years could account for part of this. Month of birth had no influence on birth weight. Calving weights differed between herds only at the second and fifth parities. Calving weights differed between sires within herds for the first five parities. Intraherd correlations between the birth weight of a heifer calf and later calving weights for her first six parities ranged from .22 to .34. Correlations between the birth weight of a calf and the average birth weight of her paternal half-sibs were .37 and .48 in the two herds. Heritabilities for birth and calving weights were of the same magnitude within herds but differed between herds. Genetic correlations between birth and adult weights were above .5 in one herd but erratic in the other herd.

Age Factors↗