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)

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.

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)

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.

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)

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.