Growth and reproductive performance of ewe lambs fed corn or soybean meal while grazing pasture.

In a 2-yr study a total of 120 Suffolk and Suffolk-cross ewe lambs, approximately 3 mo of age, were assigned within weight strata to one of three treatments: 1) control, pasture only (C), 2) .09 kg soybean meal/(hd.d) (SBM) plus pasture or 3) .45 kg whole shelled corn/(hd.) plus pasture to compare growth and reproductive performance and to determine lamb selectivity of forage quality and type. Each year, supplements were offered from June through the 3rd wk in November. Ewe lambs were managed as one flock on Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) pastures except for a brief daily supplementation period when all lambs were brought into a corral and sorted into treatment groups for the feeding. Ewe lambs were exposed to fertile rams from October 1 through the 3rd wk of November each year. Growth rates of ewe lambs grazing pasture alone were slower than those of corn-supplemented ewe lambs and were comparable to those of SBM-supplemented ewe lambs, but reproductive performances were similar (P greater than .05). Date of first detected rise in serum concentrations of progesterone and date of first observed estrus and lambing performance were similar (P greater than .05) among treatments for each year. Compared to hand-clipped forage, forage samples collected by esophageally fistulated lambs were higher (P less than .05) in crude protein and lower (P less than .05) in acid detergent fiber each year, indicating that lambs selectively grazed higher-quality forage. These data indicate that neither protein nor energy limited growth or reproductive performance of these ewe lambs.

Effect of dietary phosphorus and roughage levels on calcium, magnesium and potassium utilization by sheep.

Three levels of dietary P (.12%, .24% and .48% of dry matter) and three levels of roughage as ground corn cobs (25% 50% and 75% of dry matter) were fed in a 3 X 3 factorial metabolism trial, utilizing 36 crossbred (Hampshire X Columbia) intact male lambs, 6 to 9 mo of age. All diets contained cane molasses (5%), blood meal (13.5%), urea (1%), corn oil (1%) and salt (.5%). Limestone supplied supplemental Ca and treatment P levels were supplied by monosodium phosphate. Equal levels of corn starch and cerelose supplied the remainder of the diet. The diet was fed ad libitum, once daily. The highest P level (.48% P) resulted in a negative (P less than .01) Ca balance (-.23 g/d vs .12 g/d for .12% P and .31 g/d for .24% P groups), and apparent digestibility (P less than .01) of Ca (1.65% vs 17.18 and 22.2% for the two respective lower P dietary levels). Blood serum concentrations of Ca and Mg decreased (P less than .01) as dietary P level was increased. Apparent digestibility of Mg was decreased (P less than .05) by the highest P level (6.9% vs 21.58% and 18.80% for the two lower levels of dietary P). Level of roughage had no effect on Ca and Mg utilization; however, the highest level (75% corn cobs) resulted in improved (P less than .05) K balance (.85 g/d vs .30 and .50 g/d for the two lower levels of roughage).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of chlortetracycline for treatment of new feedlot cattle.

Two 56-d shipping fever trials of similar design were conducted the same season (fall) at Kansas State University (KSU) and at Purdue University (PU) to compare various levels of chlortetracycline (0 or 350 mg X head-1 X d-1 continuously or 1, 2 or 4 g X head-1 X d-1 for the first 14 d). Weanling crossbred steer calves were utilized (210 head of Angus X Simmental, averaging 197 kg, at KSU; 268 head of Angus X Hereford, averaging 192 kg, at PU). For the first 28 d in the KSU trial (October 13 to December 8), cattle that received 4 g X head-1 X d-1 the first 14 d gained more rapidly (P less than .05) than cattle fed 350 mg X head-1 X d-1 continuously or than the controls that received no chlortetracycline (CTC; 1.05 vs .92 or .93 kg/d, respectively). Cattle that received 4 g CTC X head-1 X d-1 for the first 14 d required less (P less than .05) dry matter per kg gain than steers that received 350 mg X head-1 X d-1 continuously over the 56-d period. In the PU trial (October 6 through December 1), all CTC treatments resulted in increased feed efficiency (P less than .05) over the controls through 28 d, and the 4 g X head-1 d-1 for 14 d and 350 mg X head-1 X d-1 continuously, improved feed efficiency over the other groups for the 56-d period.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of supplemental selenium in the serum, hair, colostrum, and fetus of parturient dairy cows.

A selenium supplementation study was conducted with Holstein cows to evaluate amounts and methods of administration, namely, oral supplementation (1 vs. 2 mg/head/d, last 60 d of gestation) and intramuscular injection (50 mg at 40 and 20 d prepartum vs. 50 mg at 60, 40, and 20 d prepartum). Blood was collected every 10 d, starting 60 d prepartum and extending 20 d postpartum for cows, and at birth to 20 d for calves. Hair samples of cows were obtained at 60 to 40 and 20 d prepartum, and of the calves at birth. Colostrum samples were obtained for assay. Oral (2 mg/d) and both injection treatments resulted in increased selenium in serum of cows, but selenium in serum of calves at birth was greater only for those whose dams received selenium by injection. Selenium in hair of cows was increased by both injection treatments as well as by the oral treatment of 2 mg/d. Selenium in hair of calves was increased by all methods of administering selenium to the dams. Selenium in colostrum was not affected by any treatment. Thus, pregnant dairy cattle respond to selenium supplementations of a daily oral intake of 2 mg/head/d, the last 60 d of gestation, or by injection of 50 mg each on d 40 and 20 prepartum.

In utero exposure of bovine fetuses to polychlorinated biphenyls.

Pregnant mature beef cows more than 6 mo from parturition were fed whole plant corn silage from either a silo (contaminated) that had been coated with a plastic containing polychlorinated biphenyls (Aroclor 1254) or from a silo (clean) that had not been coated with the plastic. In addition, a third group of cows was fed silage from the clean silo plus 200 mg Aroclor 1254 per head daily (added polychlorinated biphenyls). After 30 days on treatment, one cow from each of the three treatments had her fetus removed by Caesarean section for assay of liver, thyroid, and fat for polychlorinated biphenyls content. Tissue content of polychlorinated biphenyls for fetuses from cows fed clean silage, contaminated silage, or added polychlorinated biphenyls was (microgram/g): liver, 3.6, 4.7, and 54.1; thyroid, 2.3, 19.4, and 121.1; fat, .65, 18.1, and 130.6, indicating polychlorinated biphenyls cross the placenta readily. Cow milk (colostrum) contents of polychlorinated biphenyls on the 1st day following parturition for the three respective treatments were .54, 8.5, and 96.4 micrograms/g (clean silage, contaminated silage, and added polychlorinated biphenyls). Fetuses taken from cows that had been removed from polychlorinated biphenyl exposure for 6 mo reflected previous treatments of dams by increased fetal fat stores of polychlorinated biphenyls.

Spacelab mission 4--the first dedicated life sciences mission.

Spacelab is a large, versatile laboratory carried in the bay of the Shuttle Orbiter. The first Spacelab mission dedicated entirely to life sciences is Spacelab-4. It is scheduled for launch in late 1985 and will remain aloft for 7 d. All of the investigations are currently classified as "tentatively selected," with "final selection" and confirmation planned for late 1983. The 24 tentatively selected investigations have been combined into a comprehensive, integrated exploration of the effects of acute weightlessness as living systems. An emphasis is placed on studying physiological changes previously observed in manned space flight. This payload has complementary designs in both human and animal investigations in order to validate animal models of human physiology in weightlessness. The experimental subjects include humans, squirrel monkeys, laboratory rats, two species of plants, and frog eggs. The primary scientific objectives include study of the acute cephalic fluid shift, cardiovascular adaptation to weightlessness (including postflight reductions in orthostatic tolerance and exercise capacity), and changes in vestibular function (including space motion sickness), associated with weightlessness. Secondary scientific objectives include the study of red cell mass reduction, negative nitrogen balance, altered calcium metabolism, suppressed in vitro lymphocyte reactivity, gravitropism and phototropism in plants, and fertilization and early development in frog eggs. The rationale behind this payload, the selection process, and details of the individual investigations are presented in this paper.

Protein levels and monensin for growing and finishing steers.

One hundred sixty-eight Angus X Hereford crossbred beef steers were utilized to evaluate the influence of two levels of monensin (0 or 33 ppm) on three levels of dietary protein (9, 11 or 13% on a dry matter basis). The study was divided into a growing phase when steers received ad libitum corn silage and the needed protein supplement to supply the appropriate protein level. The finishing diet consisted of 85% dry corn and 15% corn silage plus a protein supplement to yield an 11% protein diet fed to all steers. Estimates of carcass composition were made at the beginning, at the end of the growing phase and at completion of the study. During the growing phase, growth rate (GR), dry matter intake (DMI) and efficiency of gain (F/G) were all improved (P less than .01) with increasing protein level, while monensin reduced (P less than .01) DMI and improved (P less than .01) F/G, with the greatest improvement coming on the 9% protein diet. The rate of protein deposition was increased (P less than .05) with increasing protein level and was increased (P less than .01) on the 9% protein diet while being reduced on the 13% protein diet when monensin was included in the diet. Previous protein level influenced steer performance during the finishing phase, with the steers previously receiving the 13% protein diet having the poorest GR and F/G while those having received the 11% protein diet having the highest GR.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Aroclor 1254 in the milk fat of lactating beef cattle.

Excretion in milk fat of Aroclor 1254 (a mixture of polychlorinated biphenyl) by mature beef cows (Hereford and Hereford cross) was studied. Three groups of 6 cows each were fed primarily a corn silage diet characterized by 1) clean silage (stored in an uncontaminated silo), 2) silage stored in a silo coated with a sealant containing Aroclor 1254, and 3) clean silage to which 200 mg Aroclor 1254 per head daily was added (approximately 2 to 3 mg/kg body weight per day). Treatments were started approximately 3 mo prior to parturition and extended 1 mo after parturition, at which time treatments were discontinued, and cows and nursing calves were placed on pasture. Milk was sampled in the period between parturition and 132 days after discontinuance of treatments. Fat from the milk of cows fed silage from the silo which had not been sealed with the Aroclor 1254 product contained .69 to 1.59 ppm Aroclor 1254 throughout the 164-day lactation. Fat from cows fed silage from the silo treated with the Aroclor 1254 sealant contained more than ten times as much Aroclor 1254 (15.7 to 18.4 ppm) for 32 days as compared with the controls and then dropped to one-half that figure through the 164th day. Fat from the milk of cows fed 200 mg Aroclor 1254 per day contained from 119 to 150 ppm through the first 32 days and then dropped to 39 to 51 ppm through day 164.

Trypsin and chymotrypsin development in the neonatal lamb.

Twenty-two neonatal lambs were sacrificed at various ages (0, 1, 7, 14, 21, 28, 35 and 42 days postpartum), and assays for trypsin and chymotrypsin activity were conducted on the duodenal section of the small intestine. No trypsin activity was found at birth, but gradual nonsignificant increases in activity were found through day 7 and over a fourfold increase (P less than .01) was observed between days 7 and 14, with no significant changes for the rest of the 42-day study. Chymotrypsin was present at similar levels from birth through day 7, with a twofold increase (P less than .05) in activity between day 7 and 14 and no significant change thereafter.

Selenium in milk from feeding small supplements.

Supplements of 0, 1, 2, or 5 mg of selenium from sodium selenite fed per cow daily from 90 days prepartum through approximately 6 mo of lactation had no significant effect on selenium in milk of Hereford cows. Selenium in milk was assayed 2 to 3 days postpartum (average of .014 to .023 ppm) and approximately 3 mo post parturition (average of .016 to .021 ppm). The basal diet consisted of medium quality grass-legume hay (.069 mg/kg), ad libitum liquid supplement (.152 mg/kg), and 1.36 kg shelled corn (.018 mg/kg) starting in early lactation. Treatments of selenium were administered via free-choice liquid supplement.

Selenium content of feeds and effect of dietary selenium on hair and blood serum.

A selenium depletion diet (.025 ppm selenium) was fed to two male Holstein calves for its effect on concentrations of selenium in serum. By 90 days, selenium in serum was depressed from .022 ppm to .013 ppm, and one of two calves had died of "possible white muscle disease." Repletion was rapid in that a diet containing .200 ppm selenium increased selenium in serum to .028 ppm within 2 wk. Dietary .280 ppm selenium increased it to .051 ppm in 1 wk. Eleven cows and eleven calves showed averages of .030 ppm in serum (range of .013 to .051 ppm) fed a diet of corn silage (.039 ppm) and supplement (.090 ppm). A sampling of feedstuffs showed a wide range of selenium among feedstuffs (.023 for corn cobs to 2.663 ppm for dried egg albumin) and a wide range within one type feedstuff (shelled corn, .017 to .219 ppm).