Nutrition studies (1948) of nomadic Aborigines in Arnhem Land, northern Australia.

During 1948, scientists (an anthropologist, a nutritionist and a plant ecologist) of the American-Australian Scientific Expedition to Arnhem Land observed the daily activities of families of nomadic Aborigines in the monsoonal climate of Groote Eylandt, Bickerton Island, Port Bradshaw, Yirrkala and Oenpelli, Northern Territory. The close relationship between the hunter-gatherers and the marine and terrestrial landscape is described at Hemple Bay in Port Langdon, north-eastern Groote Eylandt. Food-gathering from both land and sea was followed hourly to assess the nutritional value of 'bush tucker' in comparison with that of natives eating freshly picked fruit and vegetables grown in the garden of the Umbakumba Settlement. The ecological distributions of food plants used by the Aborigines, together with their seasonality, determined the migratory pattern of the hunter-gatherers throughout the year. With only a few exceptions, the diets which were seen at the four camps in Arnhem Land were well-balanced and provided amounts of most nutrients comparable with the recommended international dietary allowances. Seasonal and regional variations in food supply were a constant problem to these nomadic people.

Influence of nutritional restriction during late gestation on production measures and passive immunity in beef cattle.

A 2-yr study was conducted to examine the effects of nutritional restriction of beef cows during the last 90 d of gestation on neonatal immunity and production. Cows were fed corn silage, soybean meal diets; dietary treatments consisted of 1) control (CO), 100% of the NRC (1984) requirements for protein and energy, or 2) restricted (RS), 57% of the NRC requirements for energy and protein. All cows received adequate amounts of this diet postpartum. Each year, 26 Angus cows were grouped by age and weight:height ratio (WT:HT) and allotted randomly to treatments. Calves born to dams within each nutritional treatment group were allotted to one of two colostral treatments: 1) colostrum from their dam, or 2) colostrum from a cow from the other nutritional treatment group. Calves from restricted dams had higher cortisol (33.8 vs 26.1 ng/ml) and lower triiodothyronine (T3) (3.82 vs 4.01 ng/ml) concentrations (P less than .05). Maternal nutrition did not affect either colostrum immunoglobulin G (IgG) concentration (43.0 vs 39.5 mg/ml for RS and CO, respectively) or the calves' serum IgG concentration (19.06 vs 20.17 mg/ml IgG at 24 h for RS and CO, respectively). Yet, calves fed colostrum from restricted cows tended to have lower serum IgG concentration (17.2 vs 22.0 mg/ml IgG at 24 h).

Influence of glucocorticoid on macromolecular absorption and passive immunity in neonatal lambs.

The relationship of serum cortisol to immunoglobulin absorption and gut closure in cesarean-derived neonatal lambs was evaluated in two trials. In trial 1, 21 lambs were obtained on d 136 to 138 of gestation, and in trial 2, 17 lambs were obtained on d 140 to 142 of gestation. At birth, lambs were assigned randomly to four treatments: 1) control (CO), 1 ml saline/kg BW every 4 h; 2) a drug to lower cortisol (LC), 5 mg metyrapone/kg BW every 4 h; 3) single-peak cortisol (SP), 10 IU ACTH/kg BW at 0 h; or 4) elevated cortisol (HC), 5 mg cortisol/kg BW every 4 h in trial 1 or 10 IU ACTH/kg BW every 4 h in trial 2. The treatment period was 24 and 48 h after delivery for trial 1 and 2, respectively. Lambs were fed pooled bovine colostrum every 4 h for 48 h after birth at 2 and 3.5% BW for trial 1 and 2, respectively. Compared with CO, HC increased serum cortisol, LC decreased serum cortisol and SP elevated serum cortisol concentrations through at least 8 h for both trials. In trial 1, HC and SP lambs exhibited elevated serum IgG, IgM and IgA concentrations by 20 h compared with CO. However, no difference in serum immunoglobulin concentration was observed at 36 h among CO, HC and SP. Conversely, LC had the lowest immunoglobulin concentration at 36 and 48 h, and precocious closure to immunoglobulin absorption had occurred by 20 h (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal muscle protein synthesis and growth hormone secretion in young lambs treated with clenbuterol.

To determine effects of clenbuterol (CB) on muscle protein turnover and growth hormone (GH) secretion, 16 crossbred wether lambs (14.4 kg) were randomized into two groups designated to receive daily oral boluses of gelatin capsules containing corn starch with either 0 (control, CTL) or 1.87 mg/kg body weight CB for either 14 (n = 8) or 28 d (n = 8). This calculates to be approximately 40 mg CB/kg diet. Lambs had ad libitum access to a 16% crude protein corn-soy diet and feed consumption (FC) was measured. After 14 and 28 d, lambs were slaughtered and semitendinosus (ST), longissimus (LD) and brachialis (BR) muscles were exercised, weighed and analyzed for protein (TP) content. For 6 h prior to slaughter of 28-d lambs, 2.5 microCi L-[U-14C]tyrosine/kg was infused intravenously, blood was sampled and plasma was analyzed for specific radioactivity of tyrosine. Plasma GH concentrations were assessed by radioimmunoassay. No differences due to treatment were found in FC, rate of gain or GH concentrations. Semitendinosus and BR weights of control lambs at 14 d did not differ between treatments. At 28 d, ST and BR weights of control lambs (58.8 and 18.5 g, respectively) were less (P less than .10) than those of lambs treated with CB (74.3 and 23.1 g, respectively). The TP per ST and BR at 28 d for control lambs was 71.5 and 85.1% (P less than .10) that of muscles of lambs treated with CB. Fractional protein synthesis rates (FSR) of the BR (9.4 vs 6.1%/d) and total protein synthesized in ST muscle per day (1.4 vs .8 g) were elevated (P less than .10) in lambs treated with CB compared to controls. These data suggest that the increased fractional accretion rate observed in lambs treated with CB for 28 d was caused by increased FSR.

Incidence and control of subclinical mastitis in intensively managed ewes.

Ninety-three intensively managed, mature ewes were followed through three lactations to study effects and interrelationships of postweaning fast, prophylactic antibiotic injection, number of lactations and breed on subclinical mastitis, milk production and milk composition. Animals used in a 2 x 2 factorial design were allotted to treatment combinations of 1) postweaning 72 h fast or no fast, and 2) 1 x 10(6) units of procaine penicillin or sham i.m. injection at weaning. Treatments were implemented at weaning in yr 1; each ewe received the same treatment in each of the subsequent 2 yr of the study. Breeds included Finnish Landrace (F), Dorset (D), Rambouillet (R), Finnish Landrace x Dorset (FD) and Barbados Blackbelly x Dorset (BD). Milk production was greatest for D, followed by BD, FD, R and F during yr 1 (P less than .01) and overall (P less than .05). Milk production data were not collected in yr 2, but similar results were obtained in yr 3, except that the R and F exchanged rank positions. Milk composition was affected by breed. Breeds differed (P less than .05) in percentage lactose, fat and total nonfat solids in yr 1 and differed (P less than .01) in percentage lactose, fat, solids and protein across the 2 yr. A breed difference (P less than .05) was observed for incidence of mastitis at 3 wk postpartum and at weaning. Milk production was negatively correlated with incidence of mastitis (r = -.22, P less than .05). Milk production was improved (P less than .05) by a 72-h postweaning fast.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytosolic glucocorticoid receptors in skeletal muscle of the newborn calf.

A study was conducted to provide information on the characteristics of skeletal muscle glucocorticoid receptors and to determine the response of serum cortisol and thyroxine secretion to colostrum feeding in the neonatal calf. Twenty-four calves (12 males and 12 females) were obtained immediately postpartum and randomly assigned to one of two treatments after being blocked by breed and sex. The treatments consisted of: 1) pooled colostrum and 2) pooled whole milk, with both treatments being force-fed at birth, 12, 24 and 36 h postpartum. Muscle biopsies (20-30 g) were surgically removed from the right semitendinosus at 36 h postpartum from 14 of the 24 calves (7 male and 7 female). There were no glucocorticoid receptor differences in muscle samples from either the colostrum or milk-fed calves. Binding of dexamethasone to skeletal muscle cytosol indicated a moderate to high affinity (Kd = 2.34 X 10(-8)M) and a low capacity (37.61 fmol/mg cytosolic protein) binding receptor. Competition assays indicated that other non-glucocorticoid hormones had relatively high affinity for the glucocorticoid receptor. The average initial cortisol concentration was highest at birth, 127.9 (SE = 25) and 172.4 (SE = 29) ng/ml for colostrum and milk-fed calves, respectively. Following the initial peak at birth, serum cortisol concentrations declined with time (P less than .05) for both treatments. Serum thyroxine concentrations increased (P less than .05) to reach a peak of 23.3 (SE = 3.1) and 21.0 (SE = 2.9) ug/dl for colostrum and milk-fed calves, respectively, then steadily declined.

Use of injectable vitamin E and selenium-vitamin E emulsion in ewes and suckling lambs to prevent nutritional muscular dystrophy.

Forty-eight Blackbelly X Dorset, 27 Finnish, 26 Finnish X Dorset, 28 Rambouillet and 8 Dorset Suffolk-sired lambs were used in this experiment. Three weeks before lambing, one-half of the ewes received a selenium emulsion (Se-E) containing .05 mg selenium and 3.7 IU of vitamin E/kg body weight (BW). A 2 X 3 X 2 factorial arrangement was used; lambs from either treated or nontreated ewes were randomly assigned irrespective of breed to one of six treatment combinations consisting of 0 or .025 mg/kg BW selenium (Se) injected at birth or two .025 mg/kg BW Se injections, one at birth and one 2 to 3 wk later, and two levels of injectable Vitamin E (E; 0 and 100 IU) given at birth. Both lambs and ewes were provided access to 75% concentrate diets supplemented with Se and E at recommended NRC levels. Plasma activity of creatine phosphokinase (CPK) was highest at 1 d of age and exhibited decreases (P less than .001) over time. In lambs, the E injection tended to decrease plasma activity of CPK. Plasma glutathione peroxidase activity was lowest at 1 d of age and increased over the course of the experiment but was unaffected by treatments (P less than .05). Plasma tocopherol concentration decreased (P less than .01) with time, with E therapy tending to increase tocopherol concentration. Differences in mean plasma tocopherol concentrations among breeds were also observed (P less than .01). Selenium concentration increased over time and with the E injection (P less than .01). An interaction between ewe and lamb Se-E treatments also was observed (P less than .10), with nontreated lambs from nontreated ewes exhibiting lower Se concentrations than treated lambs from injected ewes. An increase in lamb plasma Se concentration was noted in response to Se-E treatments (P less than .001). In the ewes, plasma tocopherol concentration was lower while Se concentration was higher at 18 d than at 1 d postpartum (P less than .01 and P less than .001, respectively). Milk Se concentration was lower at 18 d than at 1 d (P less than .001) and was higher (P less than .10) in Se-E-treated ewes.

Dietary energy density and frame size effects on composition of gain in feedlot cattle.

Experiments were conducted to evaluate the effects of dietary energy density or genetic background on protein and fat gain of growing cattle. In Exp. 1, 24 Limousin steers were used in a growing-finishing trial. A 2 X 2 factorial arrangement was used with steers randomly allotted to four treatment combinations and fed the following diets: 80% concentrate, high moisture corn-corn silage diet (HI) or a corn silage diet (LO) during both the growing (GRO) and(or) the finishing (FIN) phases. Body composition for both experiments was determined by a deuterium oxide dilution technique. Empty body weight gains were greater (P less than .05) for HI during GRO, FIN and the total trial. Daily protein gains (DPG) were greater (P less than .05) for HI during GRO and FIN, while cattle receiving HI during at least FIN had the greatest (P less than .05) overall DPG. Daily fat gains (DFG) followed the pattern of DPG, being more rapid (P less than .05) for cattle fed HI during either GRO or FIN. Cattle fed the HI diet also tended to be more energetically efficient. In Exp. 2, large frame (LG) and small frame (SM) cattle were used for the evaluation of frame size effects on protein and fat deposition. Steers were individually fed an 80% concentrate, corn-based diet during the entire trial. Average daily gains and daily dry matter intake (P less than .05, P less than .01) were greater for LG, while feed efficiency was similar for both cattle types. Large cattle had greater (P less than .05) DPG than SM cattle, however, DFG were not different. Small frame steers were energetically more efficient (P less than .05), apparently due to composition of gain difference.

Muscle protein turnover in cattle of differing genetic backgrounds as measured by urinary N tau-methylhistidine excretion.

N tau-methylhistidine (N tau MH) was used as an index for muscle protein degradation and this index was utilized to evaluate degradation rates in young growing cattle. Initially, two Charolais crossbred heifers, 12 months of age, were used to measure the recovery of radioactivity in the urine for a 120-hour period after intravenous injection of [14C]N tau MH. Of the radioactivity injected into the animals, 89.7% was recovered after 120 hours. With rate and amount of clearance as the criteria, the excretion of N tau MH in urine appears to be a valid index of muscle protein degradation in cattle. Eight steers of two genetic types were used to evaluate the effect of frame size on turnover rates of muscle proteins with N tau MH as an index. Large frame cattle (LG) excreted more N tau MH per day (P less than 0.03) throughout the trial. Total daily creatinine excretion was less for small frame (SM) cattle (P less than 0.02) showing an increase with time (P less than 0.01) in LG and SM cattle. N tau MH-to-creatinine ratios showed a decline with time. Fractional breakdown rates (FBR) and fractional synthesis rates (FSR) appeared to parallel each other with rates tending to decrease with age. No differences were observed between LG and SM cattle for FBR, FSR or fractional growth rate (FGR).