Factors related to blood pressure in a biracial adolescent female population.

Blood pressure levels, anthropometric parameters, and dietary intakes were assessed in 1981 and 1983 in a population of black (n = 236) and white (n = 296) adolescent girls, aged 14 and 16 years in 1983. The 14-year-old black girls exhibited significantly higher mean systolic and diastolic blood pressures than whites in both years. Body weight and Quetelet index were more strongly associated with blood pressure than were height and triceps skinfold thickness. Correcting blood pressures for weight, Quetelet index, 2-year changes in height, and age at menarche decreased in each case (but did not negate) the observed race differences in blood pressure. Dietary calcium and potassium intakes were inversely related to blood pressure, and a race difference in the intake of these nutrients (whites greater than blacks) was observed. Covariate adjustment for calcium, but not for potassium, decreased the magnitude of race differences in blood pressure. Family type (single-parent vs nuclear) and place of residence (urban vs nonurban) appeared to be the most important confounding variables for race differences in blood pressure, since differences largely were eliminated by controlling for these factors. Conflicting reports in the literature regarding the age range during which race differences in blood pressure become apparent may be partially attributed to the complex interrelationships among these factors and the potential influence of other genetic-environmental interactions that may also play a role in blood pressure regulation.

Evaluation of a technique for measurement of gamma-glutamyltranspeptidase in equine urine.

gamma-Glutamyltranspeptidase (GGT) activity in equine urine was measured, using an assay developed for use with serum and was found to be reproducible. The GGT activity was measured in samples prepared by serial dilution of exogenous GGT with equine urine, and the activity was determined to be linear between 21 IU/L and 407 IU/L. The behavior of exogenously added GGT was compared in equine serum and urine. The enzyme behaved similarly in both fluids. The GGT activity was measured in serum and urine samples after storage at -20, 4, and 25 C for 24 and/or 72 hours. Enzyme activity decreased after storage at all temperatures and times, but the decrease was greatest and most variable at -20 C. The urine GGT: urine creatinine ratio was calculated on serial urine samples collected over 24 hours. Although the urine GGT activity and creatinine concentration had significant variation, the ratio remained constant. The urine GGT: urine creatinine ratio was calculated from random urine samples collected from 27 clinically healthy adult horses and was found to be 10.52 +/- 4.78 (mean +/- SD).

Relationship between final temperature, thaw rate, and quality of bovine semen.

Relationships between thaw rate, thaw bath time, and initial bath and final seminal temperature with coefficients of determination .99 and .97 were: bath time = -.01 + 220.25(1/thaw rate); initial bath temperature = final seminal temperature - 7.29 + 390.05 (1/bath time). Ejaculates from 10 bulls were split and processed in egg yolk-citrate-glycerol, egg yolk-Tris-glycerol, and whole milk-glycerol. All semen was packaged and frozen in .5-ml French straws at -196 degrees C. Sixteen thaw treatments consisted of factorial combinations of four final seminal temperatures and four thaw rates. Treatments were assessed by post-thaw acrosomal integrity after 3-h 37 degrees C incubation. Seminal quality improved with increasing final seminal temperature up to 31 degrees C and did not differ between 31 and 44 degrees C for any of the extenders. A slow thaw rate (3 degrees C/s) resulted in inferior quality for all extenders, and rates 11, 19, and 27 degrees C/s resulted in similar quality for citrate and milk extended semen. Acrosomal integrity was most for 19 degrees C/s in Tris extended semen. A significant factorial interaction existed for Tris and milk extended semen. Predicted acrosomal response of 57.7% across all extenders was at optimum final seminal temperature and thaw rate 37 degrees C and 18 degrees C/s. Bath temperature and bath time determine optimum thaw rate and final temperature of semen packaged in French straws and thus maximize seminal quality.

Preweaning growth rate and weaning traits of Angus, zebu and zebu-cross cattle.

A 4-yr study was conducted on the preweaning growth rate and weaning traits of 620 calves from: (1) Angus (A), Brahman (B), Brangus (BR) and Africander-Angus (AF) dams sired by A and B bulls; (2) BR dams mated to BR sires and (3) AF dams mated to AF sires. Heifers were placed in the breeding pastures as 2-yr-olds and exposed to bulls for 75 d. Breed groups differed (P less than .01) in weaning age (WA), average daily gain to weaning (ADG), 205-d weight (WW), conformation score and condition score. The reciprocal (A x B and B x A) crossbred calves exceeded (P less than .01) the straightbred A and B calves by 161 g (25.2%) in ADG, 36.6 kg (23.1%) in WW and 1.3 (16.7%) in condition score, but were not different in WA or conformation score. The WW of the A x B and B x A crossbred calves were similar, 194.6 and 194.2 kg, respectively. Calves sired by A bulls were born earlier (P less than .01) in the year and had higher conformation and condition scores than calves sired by B bulls. Calves sired by B bulls from BR and AF dams exceeded (P less than .01) the ADG and WW of calves sired by A bulls by 50 g and 15.6 kg, respectively. Calves from A dams were older (P less than .01) at weaning and had higher conformation scores but gained less rapidly than calves from B dams. The BR calves exceeded (P less than .01) the AF calves in WW by 14.5 kg, and the crossbred calves from BR dams exceeded (P less than .01) the crossbred calves from AF dams by 12.3 kg. Mating BR or AF dams to A sires to obtain crossbred calves did not improve calf rate of gain or weaning weight.

Effects of age, temperature-season, and breed on blood characteristics of dairy cattle.

Two hundred twenty four dairy cattle (6 mo to second calving) representing four breeds (169 Holstein, 24 Guernsey, 19 Jersey, 12 Brown Swiss) were used to determine effects of age, temperature-season, and breed on blood characteristics. A total of 1183 blood samples were collected by jugular venipuncture in the middle of each temperature-season. Covariate age affected blood profile except for hemoglobin, oxyhemoglobin, glutamic-oxalacetic transaminase, and albumin. Temperature-season increased or decreased all measures except enzyme creatine phosphokinase, total creatine phosphokinase, calcium and phosphorus. Years differed for all measures except hemoglobin and oxyhemoglobin. Except for enzyme creatine phosphokinase, total creatine phosphokinase, and phosphorus, breeds differed in other measures. There were interactions between temperature-season and year, temperature-season and breed, and year and breed. Differences among temperature-seasons were not consistent from year to year. Breed differences were not consistent from temperature-season to temperature-season for calcium or protein-bound iodine. Breed differences were not consistent from year to year for glutamic-oxaloacetic transaminase, total protein, albumin, or calcium.

Factors influencing gestation length, birth weight and calf survival of Angus, Zebu and Zebu cross beef cattle.

Day of birth in a calendar year (DB), gestation length (GL), birth weight (BW) and survival rate of calves (SR) were recorded for 4 years for single-sire matings of (1) Angus (A) and Brahman (B) sires to A, B, Brangus (BR) and Africander-Angus (AF) dams; (2) BR sires to BR dams, and (3) AF sires to AF dams, a total of four straightbred and six crossbred breed groups. Sex (S) differences were found for GL, BW and SR (P less than .05 to P less than .01), but not for DB (P greater than .05). Age of dam had no effect on GL but influenced DB (P less than .01), BW (P less than .01) and SR (P less than .05). Precalving weight of the dam influenced BW (P less than .01) but not GL. Birth weight was influenced by GL (P less than .01). Differences among breed groups were found for all traits. Purebred A had the shortest GL and the earliest BD, while purebred B had the longest GL, the latest BD, th lightest BW and the lowest SR of any of the breed groups. The BR and AF had higher BW but were generally intermediate to the A and B in other traits. Combined breed of sire and dam effects acccounted for most of the breed differences. The response and percentage heterosis obtained for such traits as DB and SR depended upon characteristics of the breeds involved and environmental factors such as date of breeding season and weather at calving. Heterosis calculated as a percentage of the A and B average was not significant for DB or GL but was 15% for BW and 14% for SR.