Liquid diets fed hourly to pigs weaned at 19 days of age and exposed to rotavirus (weanling diarrhea).

Five diets were tested for their capacity to promote weight gains in newly-weaned, 19-d-old, rotavirus-exposed pigs. The diets were tested under conditions designed to minimize the stress of weaning. That is, rotavirus-exposed pigs were moved at weaning to an isolation unit, caged individually and fed hourly liquid diets that were high (approximately 26%) and low in protein (approximately 11%). In all experiments, pigs experienced postweaning rotavirus-associated diarrhea and depression in rate of gain. Pigs grew faster: when fed diets high in protein (approximately 26% protein) vs low in protein (approximately 11% protein) and when fed diets containing cows' milk proteins vs proteins from soybean flour. A diet containing antibodies to rotavirus did not ameliorate the weanling diarrhea.

Effects of high ambient temperature on respiration rate, rectal temperature, fetal development and thyrold gland activity in tropical and temperate breeds of sheep.

The effects of high ambient temperatures on rectal temperature (RT), respiration rate (RR), fetal development and serum thyroxine (T(4)) concentrations were stuaied in two experiments involving 35 ewes and 26 lambs from the following ewe groups: 1) Barbados Blackbelly (B), a tropical breed; 2) Dorset (D), a temperate breed; and 3) Blackbelly x Dorset crosses (BxD). Data were obtained on four B, five D and five BxD ewes exhibiting estrus during the summer (Exp. 1). In Exp. 2, eight B, seven D and six BxD ewes were maintained in two environmental chambers (cool, 22.2C; hot, 33.8C) from day 125 of gestation to seven days before the expected lambing date for each breed group (D and BxD, 140+/-1; B, 144+/-1 day of gestation). The B and BxD ewes were more heat-tolerant than D ewes as measured by significantly lower RT and RR in each experiment. Mean lamb birth weight, crown-rump length, number of functional uterine caruncles and caruncle weight and size did not vary significantly among breed groups or temperature chamber (Exp. 2), and there was no indication that the high temperature imposed caused fetal dwarfing in lambs removed from the uterus at a standard age of seven days before expected parturition. Serum T(4) varied markedly among breed groups (P<0.05) in each experiment with B ewes having the lowest and BxD ewes the highest concentration. In Exp. 1, follicular stage T(4) concentrations in B and BxD ewes were lower (P<0.02) than those during the luteal stage of the estrous cycle. The decrease in D ewes was not significant. High ambient temperature (Exp. 2) depressed T(4) levels in D ewes (P<0.05) and also depressed the pituitary-thyroid response to thyrotropin releasing hormone in D lambs. Such was not the case in B and BxD ewes and their lambs.

Effects of accelerated growth during rearing on reproduction and lactation in ewes lambing at 13 to 15 months of age.

Three trials were conducted using ewe lambs to determine the effects of accelerated growth during rearing on reproduction and lactation. Data were obtained on 113 ewes. Early weaned ewe lambs were randomly assigned to the following prebreeding treatments: (1) thin (T, moderate gain) and (2) fat (F, accelerated gain). They were bred to lamb at 13 to 15 months of age. After breeding, one half of the ewes on the T and F treatments were switched to the other treatment so that postbreeding treatments were TT, TF, FF and FT. Prebreeding treatment did not affect conception rate (T, 95%; F, 96%), but lambing rates were 43, 28 and 27% higher (P<0.05) for F than T ewes in trials 1, 2 and 3, respectively. Daily milk production was higher in T ewes than F ewes for each trial, but the differences were significant only in trial 3. Estimated daily milk yields over the 60-day period were: T ewes, 1482, 1571, 1614 g; F ewes, 1183, 1373, 1321 g for trials 1, 2 and 3, respectively. Number of alveoli also favored T ewes. Switching ewes to the alternate treatment after breeding did not affect reproduction or milk production. Correlations between weight to height ratio and milk yield were negative in trials 1 and 3 but were positive in trial 2. There was no indication that serum T(4) levels affected milk production or reproduction. The results of this study show that accelerated growth during rearing increased lambing rate but may impair milk production. These effects appeared to be fixed by the time the ewes were bred.

Relationship of milk intake by sucking and by drinking to reticular-groove reactions and ingestion behavior in calves.

Two pairs of rumen-fistulated calves in early development of the rumen were fed milk by sucking and by drinking in alternating sequences to compare effects on swallowing behavior, openings and closings of reticular groove, and leakage of fluids into reticulorumen. These responses, determined primarily by palpation of the groove throughout feeding, revealed that sucking in comparison with drinking effected: longer times to complete first swallows, smaller amounts of milk per swallow, slower rates of milk intake and of swallowing, fewer sequential openings and closings of groove, lower incidence and shorter duration of groove openings, less spillage into reticulorumen, and less variability of these reactions among calves. Alternation of feeding methods from meal to meal did not change groove responses, but sucking immediately prior to drinking reduced incidence of groove openings in the latter. Presence of milk in the reticulorumen was not a consistent indicator of states of groove during ingestion. Observations emphasize importance of monitoring throughout feeding to determine changes of groove reactions and of role of calf individuality in response to feeding treatments.

Effects of methionine hydroxy analog on milk secretion and ruminal and blood variables of dairy cows fed a low fiber diet.

Twenty-eight Holstein cows were in a reversal trial to determine effects of adding 34 g/day of methionine hydroxy analog to a low fiber ration. Cows were subjected to this feeding treatment sequence after parturition: days 1 through 28, normal fiber ration; days 29 through 56, low fiber ration; days 57 through 77, low fiber ration with or without 34 g/day of methionine hydroxy analog; days 78 through 98, low fiber ration; days 99 through 119, low fiber ration with or without 34 g/day of methionine hydroxy analog (days 57 through 77 treatments reversed). Milk, rumen fluid, and blood were collected at regular intervals during each period. Overall, supplementation with methionine hydroxy analog increased only milk fat 6%. After milk fat percentage was depressed by low fiber diet, supplementation with methionine hydroxy analog increased milk fat percentage only for those cows that initially had less than 20% decrease of milk fat percentage. This enhanced milk fat percentage was accompanied by increase of ratio of ruminal acetate to propionate in animals with less than 10% depression. Supplementation with methionine hydroxy analog had no effect on blood glucose, insulin, or acetate concentrations and did not affect uptake of acetate by the mammary gland. Initial milk fat production affects the ability of methionine hydroxy analog supplementation to enhance milk fat percentage of dairy cattle fed low fiber diets.

Group-fed concentrate-silage blend versus individually-fed concentrates and group-fed silage for lactating cows.

System A provided 7.26 kg concentrate per cow daily blended and group fed with silage in 125 total and 97 selected 305-day lactations. System B provided concentrate hand-fed according to each cow's daily production (1 kg concentrate/3.25 kg milk) separate from group-fed silage in 112 total and 75 selected 305-day lactations. The 305-day records excluded those containing more than 150 days open. Both groups had, when available, 2.27 kg hay/cow daily or limited and equal grazing. Combined refusals, 5 to 10% of concentrate-silage blend in A and 5 to 10% of silage in B, plus fresh silage and 2.27 kg concentrate/cow daily constituted the common dry cow ration. Milk, milk fat percentage, and 4% fat-corrected milk, respectively, were 6,475 kg, 3.80%, and 6,270 kg in A and 6,899 kg, 3.69%, and 6,566 kg in B in the total lactations and 5,900 kg, 3.78%, and 5,686 kg in A and 6,098 kg, 3.70%, and 5,818 kg in B in the selected 305-day lactations. Percentages of solids-not-fat and protein in the milk were similar between A and B. Excluding grazing inputs, fat-corrected milk per total digestible nutrients per total lactation was 1.73 kg in both systems. Days open, days in milk, mean Wisconsin Mastitis Test score, body weight, net weight change, days to peak daily milk yield, days to minimum body weight, and minimum body weight were not different between systems in either the total or the selected 305-day lactations. Involuntary culling and culling for low production terminated 18 and 17% of the lactations started on Systems A and B.

Comparative analysis of physiologic responses to three different maximal graded exercise test protocols in healthy women.

The purpose of this study was to compare the three most commonly used maximal graded exercise test (GXT) protocols in healthy women. Submaximal and maximal metabolic and hemodynamic responses were determined from two treadmill protocols, Bruce and Balke, and a bicycle protocol, in 49 women. Maximum oxygen uptake (VO2 max) was significantly different among protocols (Bruce=40.3, Balke=38.4, and Bike=36.6 ml/kg . min -1). Maximum heart rate (HR max) was significantly lower during Bike (178 beats/min) than during Bruce (182) and Balke (183) protocols. No differences in rate of increase in HR or systolic blood pressure (BP) per increase in multiples of the rest metabolic (METs) were found between Bruce and Balke protocols. The rate of recovery of HR and systolic BP was not different among tests. Comparisons of active and sedentary groups showed differences in VO2 max and submaximal HR and recovery HR at common minutes; however, the rate of increase in HR and systolic BP during exercise and the rate of decrease during recovery were not significantly different. Prediction of VO2 max with Bruce and Balke protocols from treadmill time was r=0.91 (SEE +/- 2.7 ml/kg . min -1) and r=0.94 (SEE 2.2 ml/kg . min -1), respectively. These data suggest a difference between men and women in increased HR and systolic BP per METs increase in exertion.

Vitamin B12 administration for milk fat synthesis in lactating dairy cows fed a low fiber diet.

Thirty lactating Holstein cows were in two groups in a study of effects of vitamin B12 injections on milk fat synthesis. All cows were fed a normal fiber diet for the first 28 days after calving and then adjusted gradually to a low fiber diet over the next 28 days. After adjustment to the low fiber diet, in a single reversal trail, cows received either 150 mg of vitamin B12 in the form of hydroxocobalamin intramuscularly every 7 days for 21 days or no treatment for 21 days. Daily milk yield (kg), percent milk fat, and milk fat yield (g) for the normal fiber, low fiber adjustment, low fiber control, and low fiber plus vitamin B12 treatments were 29.6, 3.59, 1192; 31.5, 2.85, 840; 28.0, 2.58, 715; and 28.8, 2.65, 760. Injections of vitamin B12 did not correct the milk fat depression associated with the low fiber diets. In addition, there was no consistent relationship between blood B12 and milk fat production. Milk fat production was highly correlated with molar percent acetate in the rumen .63 and with blood acetate concentration .74.

Haemonchus contortus resistance in straightbred and crossbred Barbados Blackbelly sheep.

Resistance to Haemonchus contortus infection was studied in two experiments conducted with 52 lambs of widely different genetic background. Breed groups compared were: Dorset (D), Barbados Blackbelly (B), Dorset x Blackbelly (D x B), Suffolk x Blackbelly (S x B), Suffolk x Dorset x Blackbelly (S x D x B,[1/4 B]) and nonBlackbelly (NB, D and S). In each experiment, lambs were raised on concrete from birth and were essentially parasite free until infective larvae were administered. In Exp. 1, D x B, S x D x B and D wether lambs approximately 3 months old were infected with a standard dose of invective larvae estimated to be 98% H. contortus. D x B lambs had a longer (P < .05) prepatency period and, at necropsy 17-day postinfection, had a higher (P < .05) percentage of female parasites classified as immature than did the other breed groups. These data showed that the development of H. contortus larvae was inhibited in D x B host animals. In Exp. 2, B, D x B, S x B and NB ewe and wether lambs approximately 4 months old were treated with three sensitizing doses of H. contortus larvae. These were followed by a challenge infection. On the basis of fecal egg counts (eggs per gram feces, EPG), there was no evidence that the challenge infection induced a self-cure reaction in any breed group. All lambs with B breeding had significantly higher Hb levels at the end of the experiment than did NB lambs. b and S x B lambs had higher (P < .05) Hb levels than the D x B lambs, and B lambs had the highest (P < .05) mean corpuscular hemoglobin concentrations. Five days after the challenge infection, B, D x B and S x B lambs also had significantly higher white blood cell levels than did NB lambs. Significant sex differences were also observed in Exp. 2. Ewe lambs had lower final EPG levels, higher preinfection and postinfection Hb levels and higher maximum postinfection cosinophil levels. Breed x sex interactions for these parameters were not significant.

A comparative analysis of four protocols for maximal treadmill stress testing.

The purpose of this investigation was to compare the results from four commonly used maximal treadmill stress tests: Balke, Bruce, Ellestad, and a continuous multistage running protocol. The results compared serial and maximal heart rate, metabolic demands, and ECG determinations. Fifty-one healthy men, 35 to 55 years of age, volunteered for this study and were dichotomized into trained and untrained subjects. Regression analyses showed all the tests to correlate highly. No significant differences were found between tests at maximum for V02, heart rate, and blood pressure, except for V02 for the Balke as compared to the running protocol (39 vs. 41 ml./Kg-min). The Balke protocol showed lower values at maximum in VE and RP than the other three tests as well as the most gradual rate of progression in MET cost (0.5 METS per minute). The increase for the Bruce and Ellestad tests was from 1 to 1.5 METS per minute, and a rapid initial increase (9 METS in the first 3 minutes) made the running test undesirable as a screening method. Although serial plots of heart rate and MET costs were similar to those previously reported for different population samples, the present data further refined these values. Finally, a nomograph comparing treadmill time and V02, max. for the Balke, Bruce, and Ellestad tests was developed from these data.

Physical fitness levels vs selected coronary risk factors. A cross-sectional study.

Several studies show significant correlations of blood variables, weight, abnormal electrocardiograms, and blood pressure with the incidence of coronary heart disease, but the quantification of fitness and its correlation with coronary heart disease is more difficult. In this study, approximately 3,000 men, average age of 44.6 years, were examined for blood and lipid profile, pulmonary function, percent body fat determination, and Balke maximal performance treadmill stress testing with multilead ECG monitoring. Five age-adjusted cardiorespiratory fitness categories were determined from treadmill times. A consistent inverse relationship among physical fitness categories and resting heart rate, body weight, percent body fat, serum levels of cholesterol and triglycerides, glucose, and systolic blood pressure, was observed. Forced vital capacity was directly related to levels of fitness. These results, although cross-sectional, imply that physical fitness is related to lower coronary risk factors.

Prediction of body density in young and middle-aged men.

The purpose of this investigation was to predict body density of young (18-22 yr) and middle-aged (40-55 yr) men and to determine if generalized equations were appropriate to both populations. The dependent variable, body density, was determined by the hydrostatic technique. Independent variables included 7 skinfold fat, 11 girth, and 7 diameter measures; age; height; and weight. Mean body density for young men was 1.068 g/ml (SD +/- 0.014) and percent fat, 13.4 (SD +/- 6.0); the values for middle-aged subjects were 1.043 g/ml (SD +/- 0.0130) and 24.7% (SD +/- 5.9). Incomplete principal components analysis was used to examine the dimensions measured by the independent variables, and these analyses revealed differences between samples. Using multiple regression analysis, with the exception of girth measurements, the slopes of the regression lines were equal. For all analyses, however, the intercepts were different. These results confirmed the need for different regression equations for these populations. The most accurate prediction for young men was with two skinfold, four girth, and two diameter measures (R = 0.88; SE = 0.0069 g/ml); two skinfold and three girth measures accurately predicted body density for middle-aged men (R = 0.84; SE = 0.0074 g/ml).

Physiologic responses of men 49 to 65 years of age to endurance training.

A study was made of the effects of training for 30 minutes, three days a week for 20 weeks on certain physiologic measures of sedentary men between 49 and 65 years of age. Twenty-two subjects volunteered for the experimental group, and 8 others for the control group. Exercise sessions were conducted on a quarter-mile track and consisted of continuous bouts of walking and jogging. The average daily energy expenditures progressed from 228 to 365 kilocalories between weeks 4 and 20. For the same period, average exercise heart rates (HRs) progressed from 149 beats/minute (83 per cent maximum HR) to 155 beats/minute (91 per cent maximum HR). The experimental group showed significant increases in maximum oxygen intake (VO2 max) from 2.47 to 2.90 liters/minute (18 per cent) and in maximum pulmonary ventilation (VE max) from 105 to 121 liters/minute (BTPS), and decreases in resting HR, diastolic blood pressure, body weight, skinfold fat, and abdominal girth. Serum cholesterol and triglyceride levels and heart volume remained unchanged. The control subjects showed no significant changes. Regression analysis, with use of age as a covariate, showed a small but significant inverse relationship with changes in VO2 max. It was concluded that men of the 49-65 age group respond favorably to endurance exercise and show a magnitude of change similar to that found in previous investigations of similar design with younger subjects.

Frequency of training as a determinant for improvement in cardiovascular function and body composition of middle-aged men.

Frequency, duration and intensity of training have been shown to be important determinants for improving various physiological functions. This report represents a series of six training investigations conducted by the investigators over the past seven years. Within the six investigations ten separate groups were studied. These data were combined and tabulated to look at frequency of training as a determinant for improving cardiovascular function and body composition of middle-aged men. The subjects included 148 healthy, sedentary, volunteer men ranging from 28 to 64 years of age (x equal to 41). The experiments were carefully controlled and included running 30 to 45 minutes for two (four groups), three (three groups) or four (three groups) days each week for 20 weeks. The results show that all frequencies had a significant effect on cardiovascular function, but only three and four days/week regimens showed reduction in total body weight and fat. Changes in maximum oxygen consumption (VO2 max) were similar for two and three days/week programs, and significantly greater for four days. The data support the notion of frequency of training being an important criterion for improving cardiovascular function and body composition.