Internal contamination by actinides after wounding: a robust rodent model for assessment of local and distant actinide retention.

Internal contamination by actinides following wounding may occur in nuclear fuel industry workers or subsequent to terrorist activities, causing dissemination of radioactive elements. Contamination by alpha particle emitting actinides can result in pathological effects, either local or distant from the site of entry. The objective of the present study was to develop a robust experimental approach in the rat for short- and long- term actinide contamination following wounding by incision of the skin and muscles of the hind limb. Anesthetized rats were contaminated with Mixed OXide (MOX, uranium, plutonium oxides containing 7.1% plutonium) or plutonium nitrate (Pu nitrate) following wounding by deep incision of the hind leg. Actinide excretion and tissue levels were measured as well as histological changes from 2 h to 3 mo. Humid swabs were used for rapid evaluation of contamination levels and proved to be an initial guide for contamination levels. Although the activity transferred from wound to blood is higher after contamination with a moderately soluble form of plutonium (nitrate), at 7 d most of the MOX (98%) or Pu nitrate (87%) was retained at the wound site. Rapid actinide retention in liver and bone was observed within 24 h, which increased up to 3 mo. After MOX contamination, a more rapid initial urinary excretion of americium was observed compared with plutonium. At 3 mo, around 95% of activity remained at the wound site, and excretion of Pu and Am was extremely low. This experimental approach could be applied to other situations involving contamination following wounding including rupture of the dermal, vascular, and muscle barriers.

Comparison of Prussian blue and apple-pectin efficacy on 137Cs decorporation in rats.

Cesium-137 (137Cs) is one of the most important nuclear fission elements that contaminated the environment after the explosion of the Chernobyl nuclear power plant in Ukraine (1986). The aim of the study was to compare the efficacy of two chelating agent, Prussian blue and apple-pectin on 137cesium decorporation in rats. Rats were intravenously injected with a solution of 137cesium (5 kBq per rat). Chelating agents, Prussian blue or apple-pectin were given immediately after Cs contamination and during 11 days by addition of each chelating agent in drinking water at a concentration corresponding to 400 mg kg(-1) day(-1). Efficiency was evaluated 11 days after contamination (at the end of treatment) through their ability to promote Cs excretion and to reduce the radionuclide accumulation in some retention compartments (blood, liver, kidneys, spleen, skeleton and in the remaining carcass). In these conditions after treatment with Prussian blue a fivefold increase in fecal excretion of Cs was observed and was associated with a reduction in the radionuclide retention in the main organs measured. In contrast, no significant differences were observed between untreated rats and rats treated with apple-pectin. These observations were discussed in terms of ability of pectins to bind Cs and compared to recently published results obtained after treatment of Cs-contaminated children with this chelate.

Economic viability of crosses of Bos taurus and Bos indicus for dairying in warm climates.

Countries in the warm climatic zones need greater domestic supplies of milk. To increase yields, the option that is least expensive and most widely used is to cross dairy breed sires with local cattle. First generation crosses have more vigor than other crosses under stressful environmental conditions; growth rate, milk yield, and reproduction rate exceed those of local breeds and other crossbred combinations. On average, lactating first generation crosses are fed energy at 45 to 60% below their potential response, which limits their capabilities. Other crosses with local breeds fall short of first generation crosses as do some of the present synthetic breeds with 5/8 to 3/4 dairy breeding. Well-fed (> 2.5 maintenance needs) Holstein or Jersey crosses containing 1/4, 1/2, or 3/4 Bos indicus (Zebu) tend to follow projections of parental means for milk yield, reproduction rate, and tolerance to heat stress; however, for crosses, losses exceed predictions for lactation length, persistency of milk yield, feed efficiency, and rate of milking. Size of thoracic and abdominal organs, size of endocrine glands, stomach weight, and intestine length are lower than expected compared with values for purebreds. The smaller digestive system affects feeding intake of B. indicus crosses, and the smaller endocrine glands appear to limit responses to high energy diets. Possible directional dominance of B. indicus needs further investigation. The first generation crosses could support their use for dairy purposes if feeding rate and management were optimal, but prospects for other crosses remain questionable.

Comparison of lipid composition of milk from half-Danish Jersey cows and United States Jersey cows.

We studied differences in lipid composition of milk from Jersey cows with US sires and from Jersey cows with Danish sires. Milk samples were obtained on DHIA test day from 32 cows with Danish sires and 32 herdmates with US sires in two herds. The Jerseys with US sires were paired with those with Danish sires by parity and stage of lactation. Mean percentage of milk fat was 5.7%, for Jerseys with Danish sires and 4.8% for Jerseys with US sires. Total fat per day was the same (.91 kg) for both groups. Detailed analysis of milk lipids indicated that lipid composition of milk was similar for cows with US sires and those with Danish sires. However, milk from Jerseys with Danish sires contained more free cholesterol than milk from Jerseys with US sires, 17.5 versus 14.3 +/- .6 mg/dl. The proportion of polyunsaturated fatty acids was greater for milk from Jerseys with US sires than for milk from Jerseys with Danish sires (2.3 vs. 2.1%). Although lipid composition of milk from both groups was generally similar, the milk of Jersey cows with Danish sires had higher concentrations of free cholesterol and lower proportions of polyunsaturated fatty acids, both of which are possible negative factors for health of consumers.

Lactation curves for first lactation Egyptian buffalo.

First lactation records of 1538 buffalo maintained at the Animal Production Research Institute farms in 1967 to 1990 were used to determine lactation curves for three lactation lengths: > 28 and < 150 d, > 149 d, and > or = 308 d, as well as all records. Daily milk yields were summed by 14-d intervals for analyses. Yields peaked at the first, fifth, sixth, and seventh periods for > 28 and < 150 d, > 149 d, > or = 308 d, and all records. Herd-year-season significantly affected milk yield in all periods. Persistency for all records and three groupings (> 28 d, > 149 d, and > or = 308 d in milk) was highest for the > or = 308-d group (1.02 vs. .85 for > 149 d, .57 for > 28 d, and .47 for all records). Herd-year-season of calving significantly affected persistency in all records and the three subset groupings. Persistency was higher for buffalo calving in spring and summer for all records, records > 28 d, and records > 149 d but in summer and autumn for the > or = 308 d, the correlation coefficient between persistency and milk yield (r = .06) was not significant but was negative with season of calving (r =-.11).

Rates of hoof growth and wear in Holstein cattle.

Rates of hoof growth and wear were recorded on 223 Holstein cows in two herds during 20 mo. Herd 1 was mainly on pasture or dirt lots, and herd 2 was completely or partially confined in a new freestall facility. Growth and wear were measured on both dorsal and lateral surfaces of front and rear outside claws. Lateral measurements were taken 1 cm in front of the junction of wall and heel. No differences were detected in rates of hoof growth for various places on the dorsal wall. Herd effects influenced rates of growth and wear. Cow differences were not significant for hoof growth but were for a few wear rates. Monthly rates of dorsal hoof growth during first lactation were 6.04 mm for front claws and 6.58 mm for rear claws. Corresponding monthly wear rates were 5.78 and 6.11 mm, respectively. Wear rates on front and rear claws decreased with advancing stage of lactation. Front hooves grew and wore less than rear hooves. Lateral walls grew faster and wore more than dorsal walls on both front and rear hooves. Cows completely confined had higher rates of hoof growth and wear than cows on pasture. Rates of growth and wear were lowest during winter and highest during spring and summer.

Genetic and environmental variation of hoof characteristics of Holstein cattle.

Genetic and environmental components of variation of hoof measurements were ascertained from 257 Holstein heifers and 1051 cows in eight herds in North Carolina. Angles and lengths of both claws, heel depth, and base area of the hoof were measured on both right feet for four herds. Angles, lengths, and heel depths were measured only on the right rear foot for four other herds. Heritabilities combined across all lactations were .30 or above but for individual lactations were as low as .12. Number of sires ranged from 16 to 40 for individual lactations. Average repeatabilities among measurements in same lactation were mostly above .40. Age affected all hoof measurements in heifers. Herd effects had a large impact on hoof measurements. Averages for hoof angles by ages ranged from 42 degrees to 45 degrees and from 60 to 70 mm for hoof length. Ratio of length to angle ranged from 1.36 to 1.68, heel depth from 34 to 44 mm, and base areas of hoof from 93 to 103 cm2. Lengths of medial and lateral claws for front and rear feet increased with advancing age. Medial front and lateral rear claws were longer than respective opposing claws.

Reproductive traits of Holsteins and Jerseys. Effects of age, milk yield, and clinical abnormalities on involution of cervix and uterus, ovulation, estrous cycles, detection of estrus, conception rate, and days open.

Two hundred and twelve Holstein and Jersey cows were in a study to determine factors that affected reproductive traits. First ovulation occurred about 3 wk postpartum, and interval to first ovulation was greater in cows that had clinical abnormalities postpartum than in normal cows. Jerseys producing more milk ovulated sooner postpartum than lower producing herdmates. Involution of cervix and uterus occurred later postpartum in cows that had clinical problems postpartum. Involution of genital tract occurred later postpartum in older cows and sooner postpartum in cows that had higher milk yields. Duration of first postpartum estrous cycle was 4 days less than for second postpartum cycle. Percentages of estrous cycles detected by standing estrus were 43 and 73% for Holsteins and Jerseys. Estrous detection rates were highest for cows that produced slightly above the mean milk yield and did not differ between cows in highest and lowest milk production quartiles. First detected estrus and days to first insemination occurred later postpartum in Holsteins as milk yield deviation from herdmates increased, regardless of sign. In Jerseys, days to first insemination and days open increased linearly as milk yield increased. Days to first insemination and conception were greater in cows with postpartum clinical problems. Conception rate at first insemination postpartum increased in proportion to concentration of progesterone in blood samples collected during 12 days before first insemination. Overall, clinical problems at parturition and postpartum lowered reproductive performance in both breeds. There was a slight antagonism between milk yield and reproductive performance (days open) in Jerseys but not in Holsteins.