Showing papers in "Journal of Animal Science in 1979"

Cellular aspects of muscle growth: myogenic cell proliferation

Abstract: Summary Muscle differentiation and growth are accomplished by two fundamental sets of cellular processes, protein accretion and cell proliferation. This review is restricted to a discussion of the role of cell proliferation in the growth of muscle during prenatal and postnatal life. More specifically, the discussion is divided into three topic areas, which include the role of muscle precursor cell proliferation in prenatal and postnatal development and a review of factors that may be regulating the proliferation of myogenic cells. The proliferation of embryonic myogenic cells and their differentiation into multinucleated fibers, as well as the proliferation of myogenic ceils in postnatal muscle (satellite cells) are major factors determining the ultimate mass of muscle that can be produced by an animal.

Efficiency of rumen microbial growth: influence of some theoretical and experimental factors of YATP.

Abstract: Based on known metabolic pathways involved in the biosynthesis of cell macromolecules, the amount of energy (ATP) required for the formation of microbial ceils can be estimated. For a microbial rumen populat ion of mixed species, the estimated YATP (grams dry weight ceils formed per mole ATP expended) is 29 to 30 for growth on rich media containing preformed monomers and is 20 to 29 for growth on simple media containing carbohydrate and inorganic salts. The ranges in these values result from changes in the composit ion of the cells formed and not from changes in efficiencies of growth per se. Assuming equal amounts of growth in the rumen occur on rich and simple media conditions, the maximal theoretical YATP would be 26 and this might be lowered to 21, if large allowances are made for ATP expenditures for transport processes. Experimentally determined YATP values often are considerably lower than these theoretical values due to the influence of ATP expenditures for maintenance during growth and variations of YATP with growth rate. The data from nutrient-limited continuous culture (chemostat) studies of single or mixed species indicate rumen bacteria have the potential for a low growth maintenance requirement (Me) and high cell yields (YAM~X~ of 19 to 20), However, cell yields become progressively lower with decreasing growth rate, increasing Me, or both as a greater proport ion of the ATP produced is diverted to maintenance functions. M e varies

Age, season and breed effects on testicular volume and semen traits in young beef bulls.

Abstract: A total of 218 yearling Hereford, Angus, Santa Gertrudis and Brahman bulls was evaluated for semen traits and testieular volume at average ages of 16 and 20 months in April and August, respectively, during 2 successive years. Brahman bulls reached puberty at a later age than bulls of the Santa Gertrudis, Hereford and Angus breeds. Santa Gertrudis bulls had the largest testes with the Brahman having the smallest during this time span. During the summer months, when the bulls were 16 to 20 months of age, testes size, sperm motil i ty and sperm cell concentration of the ejaculate increased markedly in Brahman and Santa Gertrudis bulls. Angus bulls exhibited stable to slight increases in testes size, semen volume and semen quality, suggesting that this breed had reached its most rapid stage of development by 16 months of age. During this same period Hereford bulls showed a decline in testicular size and semen quality suggesting that Hereford bulls suffered from the environmental stresses of the semitropical summer in Florida. Within the Hereford breed, bulls from the lines of Montana origin exhibited a greater decline than those from the line originating in Florida. (

Follicular development during four stages of the estrous cycle of beef cattle.

Abstract: Estrogen and progestin concentrations in plasma and follicular fluid (FF) of follicles within the small (5 to 100/A), medium (101 to 400 gd) and large (>400 gtl) range, numbers of follicles and volume of FF per follicle within these ranges were determined in beef heifers. There were differences (P<.01) in mean concentrations (+SE) of steroids among and within follicles from the small, medium and large ranges during the estrous cycle. Concentrations of progestins were highest in follicles within the small range (178 -+ 12 ng/ml);-whereas, concentrations of estrogens were highest in follicles in the large range (55 + 8 ng/ml). Mean ratio of progestins: estrogens was 12:1 in small follicles, 4:1 in medium follicles and 2:1 in large follicles. Volumes of FF from follicles within the small, medium and large ranges varied (P<.01) throughout a cycle. Mean volumes of FF from follicles in the medium and large range increased 130% and 180%, respectively, as time of ovulation neared. In contrast, mean volumes of FF from follicles within the small range decreased 170%. Total numbers of follicles per pair of ovaries and heifers with follicles in the large range increased (P<.01) toward the end of the estrous cycle. (

Selection for ovulation rate in swine: correlated response in litter size and weight.

Abstract: Nine generations of direct selection for ovulation rate (OR) were evaluated to determine the magnitude of the correlated response in three litter size and two litter weight traits. A total of 387 Select line and 394 Control line litters were included in the ten generations of data. Realized heritabili ty of OR was .42 -+ .06 based on the regression of response (SelectControl) on weighted cumulative selection differential. Regressions of line means on generation number were significant for lit ter birth weight in both lines (-.31 +.12 kg, Select ;.41 -+ .06 kg, Control) and for lit ter weaning weight (-3.4 -+ .8 kg) in the Control line. None of the other regressions of line means on generation number was significantly different from zero. Regressions of line difference (Select-Control) on generation number were .06 -+ .07, .07 -+ .07, .10 _+ .07, .10 +.10 kg and 1.2 -+ .8 kg for total number farrowed (TNF), number farrowed alive (NFA), number weaned (NW), l i t ter birth weight (LBW), and litter weaning weight (LWW), respectively. However, none of these estimates of correlated response was significantly different from zero. Estimates of realized genetic correlation obtained were .07 (OR-TNF), .11 (OR-NFA),

Free amino acids in blood of ruminants--physiological and nutritional regulation.

Abstract: Tissue free amino acid pools account for only a small fraction of the total amino acid content in the body. Blood of plasma free amino acid pools represent only a very small proportion of tissue free amino pools. Plasma free amino acid profiles have been used as a tool to study nutritional and metabolic aspects of protein status. Static measurements of plasma amino acid levels have limited value as sensitive indicators of protein status because such measurements do not reflect the magnitude of amino acid fluxes in and out free amino acid pools. Use of plasma amino acid profiles, under well defined experimental conditions, in assessing limiting amino acids and essential amino acid requirements in ruminants is discussed.

Influence of an Experimental Infection of Ascaris suum on Performance of Pigs

Abstract: Thirty-two pigs (average 26.6 kg live weight) were individually housed and fed to study the effect of an infection of Ascaris suum (either 0, 600, 6,000 or 60,000 A. suum eggs/pig) on performance of growing-finishing pigs. Increasing the level of A. suum infection produced linear (P less than .07) and quadratic (P less than .09) effects on final weight, weight gain and average daily gain. Feed to gain ratio and number of A. suum worms recovered from the intestines of pigs at slaughter increased linearly (P less than .01) with increasing doses of A. suum eggs. Pigs receiving 60,000 A. suum eggs were 13% less (P less than .01) efficient than the noninfected controls. In each of two trials, eight crossbred barrows (15.7 kg in trial 1 and 16.1 kg body weight in trial 2) were examined for the effects of two levels of A. suum infection (0 and 20,000 eggs/pig) on digestibility coefficients for dry matter, crude protein and gross energy. The infection did not affect (P greater than .05) digestibility coefficients during the first two collection periods (d 6 through 10 and 19 through 23). However, digestion coefficients for dry matter, crude protein and gross energy obtained from the total collection period on d 33 through 37 postinfection were greater (P less than .01) for control pigs than for pigs given 20,000 A. suum eggs each. Also, N retention was greater (P less than .05) for control pigs than for infected pigs.

Method for Obtaining Ovine Uterine Secretions from Unilaterally Pregnant Ewes

Abstract: Development of the ovine conceptus was confined to the uterine horn ipsilateral to the corpus luteum (CL) by placing a ligature around that uterine horn at a point near the uterine body on day 5 of pregnancy. On day 140 of gestation, seven of 10 ewes were still pregnant and from 21 to 815 ml of uterine fluid (488 +/- 94 ml, X +/- SEM) were collected from the nongravid uterine horn. Total recoverable protein (X +/- SEM) was 13.4 +/- 3.4 grams. Polyacrylamide gel electrophoresis of the reduced proteins in presence of sodium dodecyl sulfate indicated that protein composition of uterine fluid was distinct from that of colostrum, serum, amniotic fluid, and allantoic fluid, and revealed the presence of two major polypeptides with molecular weights of about 57,000 and 58,500, respectively, plus numerous other minor components. Gel filtration on columns of Sephadex G-200 and Sepharose CL-6B suggested that these polypeptides formed a series of aggregates of high molecular weight when kept under nonreducing conditions. Glucose (.18 +/- .03 mg/ml), but not fructose, was present in uterine fluid. In addition, high levels of prostaglandin F (451.4 +/- 83.3 ng/ml) were present.