Biomedical subjects

E H Jaster

Publications and source records attributed to E H Jaster.

23 records · Page 2Linked to original sources

PubMed1983

Feeding supplemental niacin for milk production in six dairy herds.

Six dairy farms representing 300 lactating dairy cows were used to assess effects of feeding 6 g of supplemental niacin during the first 10 wk of lactation. Means for niacin and control cows for 10 wk postpartum were 31.2 and 31.1 kg/day milk, 3.7 and 3.6% milk fat, and 30.3 and 30.2 kg/day 4% fat-corrected milk. A scoring system with 1 to 5 scale was utilized to measure body condition of dairy cows at parturition. Average body condition score for niacin and control cows at calving was 3.1. High producing heifers in first lactation receiving niacin (greater than 28 kg/day of milk) produced more milk than controls (31.8 compared to 30.2 kg/day). Thin cows (body condition score 2) receiving niacin produced less milk than controls with a body condition score of 2 (27.0 compared to 30.7 kg/day). Analyzing body condition scores 3 and 4 revealed no difference of milk production for niacin and control groups; however, milk production increased as scores for body condition increased.

Animals↗

PubMed1983

Influence of the estrous cycle on selected biochemical and cytologic characteristics of milk of cows with subclinical mastitis.

The purpose in this experiment was to determine the relationship between subclinical mastitis and the estrous cycle. Subclinical mastitis was defined as a quarter in which milk had a somatic cell concentration greater than 500,000/ml and was bacteriologic culture-positive on 2 consecutive examinations. Normal quarters were defined as quarters from which milk had a somatic cell concentration less than 500,000/ml and was bacteriologic culture-negative on 2 consecutive examinations. Selected biochemical and cytologic characteristics of milk from 10 cows with subclinical mastitis were measured at 5-day intervals during the estrous cycle. Milk and blood progesterone concentrations were determined. Analysis of variance of dependent variables was performed, using a model with the following factors: cows, treatments, days of estrous cycle, and interaction of treatment with day of the estrous cycle. Treatment consisted of comparison of normal and subclinically mastitic quarters. Clinical signs of mastitis tended to occur more often during estrus (days 0 and 20) than during diestrus (day 10). Day of the estrous cycle was a significant source of variation for bovine serum albumin concentrations in milk. Somatic cell concentrations, electrical conductivity, milk bacterial concentrations, and log10 milk bacterial concentrations did not vary significantly during days of the estrous cycle. A significant treatment-by-day interaction occurred for milk progesterone concentrations; blood progesterone concentrations were not similarly affected. Milk progesterone concentrations for mastitic and normal quarters were similar at estrus (days 0 and 20) and metestrus (day 5). Milk progesterone concentrations for mastitic quarters were significantly decreased on day 15 of the estrous cycle, compared with values from normal quarters.

Analysis of Variance↗

PubMed1982

Influence of season on timed inseminations of dairy heifers synchronized by prostaglandin F2 alpha.

Sixty-six cycling Holstein heifers were given two injections of prostaglandin F2 alpha (25 mg intramuscular) at an 11-day interval. Average time of first observation of estrus differed little between July (55.7 +/- 5.3 h) and December, 1980 (50.6 +/- 5.1 h). Heifers were inseminated artificially at either 65 or 80 h following the second injection of prostaglandin. Synchronized heifers inseminated at 65 h had a higher conception rate in July (9/18; 50%) than in December (3/15; 20%). However, heifers inseminated at 80 h had a similar conception rate in July (9/18; 50%) and in December (8/15; 53%). Progesterone in blood serum was measured prior to the second prostaglandin F2 alpha injection before insemination and on day 21 postbreeding. Averages of progesterone for the 65-h group were 3.91 +/- .48, .39 +/- .07, and 3.80 +/- .76 ng/ml in July and 4.25 +/- .44, .33 +/- .08, and 3.91 +/- .63 ng/ml in December for the three collections. Averages for the 80-h group were 3.62 +/- .28, 1.06 +/- .56, and 3.60 +/- .65 ng/ml in July and 2.17 +/- .35, .22 +/- .07, and 2.77 +/- .43 ng/ml in December. An influence of season on response to prostaglandin and timed inseminations in dairy heifers may affect estrus behavior and conception rate.

Animals↗

PubMed1982

Effect of an intramammary polyethylene device in primiparous dairy cows.

A sterilized polyethylene intramammary device (IMD) was inserted through the papillary duct into a front and a rear mammary quarter of 12 primiparous dairy cows, which were mastitis-free. This study was conducted during lactation from month 1 postpartum to completion (generally month 9). After the device was inserted, milk somatic cell counts (SCC) increased. Milk scc in the quarters fitted with IMD from foremilk, primary, and stripping samples were 5.2, 2.6, and 5.9 X 10(5) cells/ml, respectively. Comparable counts for control quarters were 2.1, 1.4, and 3.6 X 10(5) cells/ml. The SCC in foremilk from the quarters fitted with the device were 2 to 3 times greater than the counts in foremilk from control quarters during month 2 and subsequent months of lactation. The SCC were significantly increased in primary and stripping samples from quarters fitted with IMD; however, the SCC of 2.6 X 10(5) cells/ml in primary milk would not affect market milk quality. Milk production for the lactation was decreased (0.6 kg/quarter/day) in the quarters fitted with IMD in comparison with control quarters throughout the lactation. There were no differences in percentages of milk fat or protein between deviced and control quarters. Conductivity values were increased in foremilk and stripping samples, but not in primary samples, for the quarters with IMD. Bovine serum albumin concentrations were also increased.

Animals↗

PubMed1981

Beta-adrenergic receptor involvement in lipolysis of dairy cattle subcutaneous adipose tissue during dry and lactating state.

The influence of lactation on beta-adrenergic receptor kinetics was studied with adipocytes from eight Holstein cows during two physiological states, dry period 30 days prepartum and 30 days postpartum or early lactation. Physiological state had no effect on binding kinetics of (--)-hydrogen-3 labeled dihydroalprenolol. Affinity rate constants (8.2 versus 7.2 X 10(7) min-1 M-1) and equilibrium dissociation constants (7.1 versus 7.9 nM) for both prepartum and postpartum periods were similar. In contrast, the apparent number of beta-adrenergic receptors varied with lactational state (42,154 versus 72,264 sites/cell) for dry and lactating status as estimated in assays containing 5 nM (--)-hydrogen-3 dihydroalprenolol. Glycerol release and adipocyte concentrations of adenosine-3',5'-cyclic phosphoric acid were assayed with or without 10 microM epinephrine. Epinephrine elicited greater release of glycerol in adipocytes from lactating than dry cows (3.91 versus 2.1 mumol/10(6) cells/120 min). The concentration of adenosine-3',5'-cyclic phosphoric acid rose during the first 5 min of incubation in the presence of epinephrine and then fell to base after 10 min. Maximum concentrations at 5 min were not different in adipocytes from dry and lactating cows (250 versus 280 pmol/10(6) cells).

Adipose Tissue↗