PubMed Health⌕ Search

Biomedical subjects

J G Linn

Publications and source records attributed to J G Linn.

At least 19 recordsLinked to original sources
PubMed2003

Comparison of feeding corn silages from leafy or conventional corn hybrids to lactating dairy cows.

Three corn hybrids (Pioneer 36F30, Mycogen TMF2450, and Mycogen TMF2404) were compared for yield and quality traits, and lactation performance and apparent digestibility by Holstein cows. The three corn silages were harvested at a target of 33 to 35% dry matter. Before harvest, six corn plants were randomly selected for plant fractionation. Grain-to-stover ratios were 0.92, 0.70, and 0.95 for the 36F30, TMF2450, and TMF2404 corn plants, respectively. Fifty-two multiparous Holstein cows were placed on a 120-d lactation trial after a 21-d covariate diet. Cows were blocked by calving date and randomly assigned within block to one of three dietary treatments, containing approximately 40% (dry matter basis) corn silage. Milk yield, milk components, and dry matter intake did not differ among dietary treatments. In vitro true and neutral detergent fiber digestibilities were numerically higher for TMF2404 than the other corn silage hybrids. Apparent total-tract crude protein and neutral detergent fiber digestibilities, as measured by acid insoluble ash, were higher for TMF2450 than the other two hybrids, but starch digestibility was not different between the corn silage dietary treatments. Although small differences in nutrient content and digestibility existed among corn silage hybrids, inclusion of these leafy hybrids in lactating cow diets at 40% of the dietary dry matter did not have a significant impact on lactation performance of dairy cattle.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Reaching impaired populations with HIV prevention programs: a clinical trial for homeless mentally ill African-American men.

This study tested an intervention to reduce sexual risk behaviors in a high risk impaired population: homeless African-American, Caucasian and Hispanic men with mental illness. In a comparison group clinical trial, men were assigned to an experimental cognitive-behavioral or a control intervention and followed up over 16 months. Men were recruited from a psychiatric program in two shelters for homeless men in Nashville, Tennessee. An ethnically mixed cohort of subjects (54% African-American, 42% Caucasian and 4% Hispanic) were included in the study. Most had a chronic psychiatric disorder and a co-morbid substance abuse disorder. The 257 participants who were sexually active (130 experimental, 127 control) prior to the trial were the main target of the intervention. An experimental intervention (SexG), adapted from Susser and Associates (51), comprised 6 group sessions. The control intervention was a 6-session HIV educational program. Sexual risk behavior was the primary outcome. The experimental and control groups were compared with respect to the mean score on a sexual risk index. Complete follow-up data were obtained on 257 men (100%) for the initial six-month follow-up. These individuals have been followed for the remainder of the 16-month follow-up. This intervention, (SexG), successfully reduced sexual risk behaviors of homeless mentally ill African-American, Caucasian and Hispanic men. Similar approaches may be effective in other impaired high-risk populations.

Acquired Immunodeficiency Syndrome↗
PubMed2001

HIV prevention for indigenous people of the Amazon basin.

This study identifies theoretically-based predictors of condom use in a sample of 251 sexually active adults recruited from Sao Gabriel da Cachoeira and six indigneous communities of the Upper Rio Negro region of Amazonas Brazil. The information-motivation-behavioral skills (IMB) model of AIDS-preventive behavior was used to describe the roles of HIV/AIDS knowledge, experiences with and attitudes toward condom use, peer influences, perceived vulnerability, monogamy and behavioral skills. A predictive path analytic model revealed significant predictors of more condom use including male gender, greater sexual HIV knowledge, positive experiences and attitudes about condom use, multiple partners, and greater behavioral skills. Results suggest that attention to behavioral skills for negotiating safer sex and instruction in the correct use of condoms are important elements in reducing high risk behaviors. Increasing the specific knowledge level of indigenous people regarding the complexities of sexual transmission of HIV is crucial and should be addressed. Heightening individuals' understanding of the limited protection of serial monogamy, and the need to conduct gender-specific training for behavior change to reduce transmission of HIV should be an additional goal of Brazilian health professionals. Obstacles to the implementation of the IMB HIV prevention program in Amazonas are noted and an alternative Brazilian HIV/AIDS prevention program is discussed.

Adolescent↗
PubMed1999

Effect of feeding silages from corn hybrids selected for leafiness or grain to lactating dairy cattle.

Three corn hybrids were harvested as silage and fed to lactating dairy cows to determine performance and digestibility differences between hybrids. Corn hybrids were a grain type, a generic blend, and a leafy type. Starch content of the grain, blend, and leafy silage hybrids was 26.1, 23.8, and 23.5%, respectively. In vitro digestible dry matter of the leafy hybrid silage (69.2%) was higher than the grain (66.8%) or blend (66.7%) hybrid silage. Sixty-two Holstein cows (39 primiparous and 23 multiparous) were fed diets containing (dry matter basis) 40.6% of one of the corn silages, 10.2% alfalfa haylage, 23.5% corn grain, 7.4% whole-fuzzy cotton-seed, 13.8% protein concentrate, and 4.5% vitamin and mineral mix. Cows were assigned to their silage treatment diet 3 d after parturition and remained on the diet until wk 22 of lactation. Dry matter intake, milk yield, and milk components did not differ for cows fed the grain, leafy, or generic blend silage diets for either parity group. Digestibilities of dry matter, organic matter, and neutral detergent fiber, and rate of passage were not different across the silage diets for either parity. Multiparous cows receiving the blend silage diet lost more weight throughout the 22-wk study than did cows on the leafy or grain silage diets. Primiparous cows receiving the blend silage diet spent more time eating than cows on either the grain or leafy silage diet. Time spent chewing did not differ among hybrids. Corn hybrid at 40% of dietary dry matter as silage did not have a major impact on dairy cattle performance in this trial.

Animal Nutritional Physiological Phenomena↗
PubMed1997

Stress, appraisal and coping in HIV-infected African-American men and women.

With the development and utilization of the new multidrug therapies, many persons with HIV have experienced dramatic improvements in their physical condition, health self-appraisal, and psychological well-being. This treatment process has demonstrated the interrelationship of physical stress, perceived health status, and successful coping with HIV illness. The objective of this analysis is to assess the importance of perceived health for the level of mental distress in African-American men and women who have HIV disease. Interviews were completed with 255 HIV-infected black adults (age > or = 18) who were clients of AIDS care and referral centers in Tennessee. The results suggest that persons with a positive health appraisal are more effectively coping with the stresses of HIV illness. These observations have clinical implications for the care of African-Americans and others with HIV/AIDS.

Adaptation, Psychological↗
PubMed1996

Self-appraised health, HIV infection, and depression in female clients of AIDS counseling centers.

The development of effective coping strategies may require that women and men with HIV have an accurate, and to the greatest extent possible, positive, perception of their own health status. This has been found to be lacking among HIV-infected persons with limited education/information, including many minority adults. The objective of this study is to test several hypotheses that predict depression and perceived health in female adults with HIV. Data were obtained from 103 HIV-infected women (age > or = 18) who sought support, counseling, and maintenance services from one of four HIV care and referral centers in the mid-South. The results emphasize that perceived health status may fulfill a psychological distress-moderating or distress-aggravating function for women with HIV/AIDS.

Adaptation, Psychological↗
PubMed1996

Responses of dairy cows supplemented with somatotropin during weeks 5 through 43 of lactation.

Beginning at wk 5 of lactation, 136 cows (34 per treatment) were supplemented daily for 38 wk with 0, 10.3, 20.6, or 41.2 mg of recombinantly derived bST monomer. Cows were obtained from University of Kentucky, University of Minnesota, University of Pennsylvania, and The Ohio State University. Nine cows (4 at 0 mg/d, 1 at 10.3 mg/d, 1 at 20.6 mg/d, and 3 at 41.2 mg/d) did not complete the experiment because of health problems. Data from these cows were included in the reproduction and health databases but not in the production database. Cows supplemented with bST produced more milk, consumed more feed, had lower rates of BW gain, and had improved efficiencies of milk production (conversion of feed and NEL to milk). Additional increases in productivity were modest at 20.6 and 41.2 mg/d versus productivity at 10.3 mg/d of bST. Concentrations of fat, protein, and TS in milk were unaffected. At 10.3 mg/d, bST did not adversely affect reproduction or health.

Animal Nutritional Physiological Phenomena↗
PubMed1996

Effect of concentrate source and amount in diets on plasma hormone concentrations of prepubertal heifers.

Effects of concentrate source (corn or soybean hulls) and amount (40 or 80% of DMI) on plasma hormone concentrations were evaluated for 32 prepubertal Holstein heifers in a 2 x 2 factorial design. Blood samples were collected every other day from d -4 through d 28 of the experiment and were analyzed for growth hormone, prolactin, IGF-1, and glucose. Ruminal samples were collected by esophageal tube on d 0, 7, 14, 21, and 28 and were analyzed for VFA content. Serial blood samples were collected on either d 25 or 26 at 20-min intervals for 8 h and were used for profile analysis of growth hormone and prolactin. Heifers fed 80% concentrate had higher IGF-1 concentrations in serum (158.1 vs. 131.9 ng/ml) than did heifers fed 40% concentrate, and heifers fed corn tended to have higher IGF-1 concentrations than heifers fed soybean hulls. Prolactin concentrations in samples that were collected every other day were higher for heifers fed the 80% soybean hull diet than for those fed 40% concentrate diets or the 80% corn diet. Effects of source and amount of concentrate on plasma prolactin concentrations were not evident in serial samples. Concentrate source or amount had no effect on plasma growth hormone or glucose. At high concentrate intakes, the source (soybean hulls vs. corn) affected intake parameters, ruminal VFA content, and prolactin concentrations.

Acetates↗
PubMed1995

Psychosocial outcomes of HIV illness in male and female African American clients.

With the rapid growth of HIV infection among African Americans, the issue of how medical problems relate to psychological functioning in the black community population has acquired new meaning and urgency for health care policy. To develop effective strategies to meet the mental health needs of infected African Americans we need a better understanding of the pattern of Association between HIV and psychological distress. The objective of this study is to test several hypotheses that predict depression and anxiety in black adults infected with HIV. Our conceptual model is derived from learned helplessness theory (Seligman, 1975), the concept of perceived coherence (Antonovsky, 1980; Lewis & Gallison, 1989), and social support theory (Cohen & Willis, 1985). Instruments used in the study include: The Center for Epidemiological Studies-Depression (CES-D) Scale (Radloff, 1977), the Anxiety Scale (Lewis, Firsich, and Parsell, 1979), and the Perceived Coherence Scale (Lewis, 1989). Data were obtained from 255 HIV infected black males and females (age > or = 18) who sought support, counseling, and maintenance services from one of three HIV care and referral centers in the Mid-South. The results of the study emphasize the relative importance of perceived physical symptoms over stage of illness for psychological functioning among African American adults with HIV. Further, the findings also demonstrate the potential importance of perceived coherence for psychological functioning. Black clients who reported higher perceived coherence, regardless of the stage of illness or level of HIV symptoms, had lower anxiety and depression. Significant gender differences in depression are also observed and implications are drawn for strategies to address HIV related mental health care needs of African Americans.

Adaptation, Psychological↗
PubMed1995

Early lactation responses of Holstein cows fed a rumen-inert fat prepartum, postpartum, or both.

Primiparous (n = 22) and multiparous (n = 41) cows were randomly assigned by calving date and parity to one of four dietary sequences of supplemental fat from 14 d prepartum to 151 d postpartum. Partially hydrogenated tallow was added to diets at 0% prepartum and postpartum (control); 1% prepartum and 2% postpartum; 0% prepartum and 2% postpartum; and 0% prepartum, 0% from 1 to 34 d postpartum, and 2% from 35 to 151 d postpartum. Inclusion of partially hydrogenated tallow did not influence yields of milk or 3.5% FCM, milk composition, or DMI during the first 151 d postpartum. During the first 35 d postpartum, cows receiving partially hydrogenated tallow starting at parturition yielded milk with a higher fat content than those receiving fat prepartum and postpartum. Addition of partially hydrogenated tallow to diets starting 35 d postpartum resulted in cows being more persistent in yields of milk and 3.5% FCM from 60 to 151 d postpartum. Reproduction parameters measured were unaffected by time of fat addition to diets. Our data suggest that delaying the addition of partially hydrogenated tallow to diets until 35 d postpartum may improve the persistency of lactation.

Animals↗
PubMed1994

Multi-farm use of bovine somatotropin for two consecutive lactations and its effects on lactational performance, health, and reproduction.

In a two-lactation study, 352 Holstein cows (124 primiparous) from six commercial dairy herds were assigned to daily injections of bST. Dosages were 0 (control), 5.15, 10.3, or 16.5 mg/d of bST; injections began 28 to 35 d postpartum. During yr 1, FCM production increased linearly as bST dose increased for primiparous and multiparous cows. However, FCM production for primiparous cows that were retained for yr 2 was not increased by bST, and the increase in FCM for multiparous cows was only 67% of that observed during yr 1 for doses of 10.3 and 16.5 mg/d. Milk SCC were not increased with the use of bST during either lactation. Days to conception of multiparous cows during yr 1 tended to increase linearly with increasing dose. Multiparous cows administered bST during yr 2 tended to have a lower conception rate than control cows (71 vs. 87%, respectively). Body condition was decreased linearly by bST dose at the end of yr 1 and 2. Prior to receiving bST during yr 2, bST-treated cows regained less body condition than control cows. Number of health disorders at parturition and assisted births of cows that received bST during yr 1 were unaffected by previous treatment. General health, ratio of single to multiple births, and BW gain of calves was similar among treatments.

Animals↗
PubMed1994

Evaluation of calf starters containing different amounts of crude protein for growth of Holstein calves.

Holstein calves (n = 110) were used to evaluate the effect of calf starters containing 15, 16.8, 19.6, or 22.4% CP, DM basis (diets A, B, C, and D, respectively), on calf performance from d 4 to 56 of life. Preweaning daily gain tended to increase linearly as protein content of diets increased, averaging .37, .39, .38, and .44 kg/d for diets A, B, C, and D, respectively. After weaning, calves fed diet C gained the most (.86 versus .71, .75, and .79 kg/d for A, B, and D, respectively). Overall BW gains from d 4 to 56 averaged .54, .56, .62, and .61 kg/d for A, B, C, and D, respectively. Throughout the experiment, starter consumption tended to increase as CP content of diet increased. Under these conditions, maximum growth was supported by diet C (19.6% CP); no advantage was gained from higher (22.4%) protein content. Calf growth was moderate when calf starters of lower protein contents (15 or 16.8%) were fed.

Aging↗
PubMed1994

Effects of calcium salts of long-chain fatty acids added to a diet containing choice white grease on lactation performance.

We studied the effect of increased energy density of diets during early lactation on lactational performance of cows injected with bST. Total mixed rations contained 50% forage (DM) and 2.5% choice white grease during the first 14 wk of lactation. Thirty cows were fed diets with grease as the only supplemental fat, and 15 cows were fed grease plus 1.8% calcium salts of long-chain fatty acids. One-half of the cows fed grease and all cows fed grease plus calcium salts of long-chain fatty acids received 640 mg/28 d of sustained-release bST from 6 to 44 wk postpartum. Calcium salts of long-chain fatty acids did not increase milk yield, 3.5% FCM, or DMI during the first 14 wk postpartum or during 15 to 44 wk postpartum. Administration of bST increased milk fat concentration .4% units during the first 14 wk postpartum. Cows receiving bST had higher DMI and produced 18.5% more 3.5% FCM from 15 to 44 wk postpartum than did controls. Calcium salts of long-chain fatty acids or bST injections did not influence body condition score or BW. These data suggest that cows yielding 30 to 35 kg of milk/d during the first 14 wk of lactation may not respond to added fat over 2.5%.

Animals↗
PubMed1994

The effect of dietary energy concentration on calf performance.

At three locations, 120 calves were fed a high fat milk replacer at 10% of birth weight from d 5 through 13. On d 14, calves were assigned randomly within sex and date of birth to a 2 x 2 factorial arrangement of treatments. Treatments were (on a DM basis) high fat milk replacer (21.6%) and high fat starter (7.3%), high fat milk replacer (21.6%) and low fat starter (3.7%), low fat milk replacer (15.6%) and high fat starter (7.3%), and low fat milk replacer (15.6%) and low fat starter (3.7%). Milk replacer was fed at 8% of birth weight/d from d 14 to 35 and at 4% of birth weight/d from d 36 to 42. High fat replacer depressed DMI before and after weaning. High fat starter depressed DMI after weaning. Before weaning, calves gained more BW when fed low fat replacer. Calves fed low fat starter gained more BW after weaning. On d 56, BW were highest for calves fed low fat replacer and starter and lowest for those fed high fat replacer and starter. Growth or health of calves was not improved by fat addition to the diet.

Animal Feed↗
PubMed1993

Lupins (Lupinus albus) as a protein supplement for lactating Holstein dairy cows.

Three experiments were conducted to determine optimal substitution of lupin for soybean meal in dairy cattle diets; the effects of whole versus ground lupins and the effects of whole lupins versus whole soybeans on milk production were examined. In the first experiment, 57 cows were assigned randomly to treatments in blocks of five by calving order within parity. Treatments began 22 d postpartum and continued through d 140. Diets were isonitrogenously balanced using soybean meal as control: lupins replaced 0, 25, 50, 75, and 100% of supplemental protein. Cows that consumed 75% of supplemental protein as lupins produced more 3.5% FCM and fat than cows that consumed the control diet. In a second experiment, 30 primiparous cows were assigned randomly by calving order to either ground or whole lupins (60% of supplemental protein). Treatments began 32 +/- 3 d after calving and lasted for 84 d. Cows that consumed ground lupins produced more milk and 3.5% FCM than cows that consumed whole lupins. In the third experiment of 84 d, 28 primiparous midlactation cows were assigned randomly to diets containing whole lupins or whole soybeans to supply 1 kg of supplemental protein. Cows fed whole lupins produced milk with higher fat content, more 3.5% FCM, and more fat than cows consuming whole soybeans. Lupins are an acceptable supplemental protein source for dairy cows.

Animal Nutritional Physiological Phenomena↗
PubMed1993

HIV-illness, social support, sense of coherence, and psychosocial well-being in a sample of help-seeking adults.

This study tests a set of hypotheses that predict self-esteem and anxiety in adults infected with human immunodeficiency virus (HIV). The analysis is motivated by the following question: Is the level of perceived coherence, i.e., the extent to which individuals derive meaning and purpose in their lives despite their HIV-illness, related to their levels of self-esteem and anxiety? Data were obtained from one of three HIV care and referral centers in the Midsouth. The results demonstrate that clients who experienced a greater sense of derived meaning and purpose (perceived coherence) from their situations and those with more confidants (social support) reported higher self-esteem and lower anxiety than other HIV-infected adults seeking counseling and maintenance services. Implications are drawn for strategies to meet HIV-related mental health care needs.

AIDS-Related Complex↗