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Biomedical subjects

Y Folman

Publications and source records attributed to Y Folman.

At least 73 records · Page 4Linked to original sources
PubMed1982

Effect of climatic conditions on peripheral concentrations of LH, progesterone and oestradiol-17 beta in high milk-yielding cows.

In a subtropical climate, high milk-yielding dairy cows were kept during the summer under ventilated conditions or untreated; during the winter, cows were kept untreated. The afternoon mean rectal temperature for multiparous cows in the three groups was 39.3, 39.8 and 38.9 degrees C, respectively. Each group was significantly different from the other two (P less than 0.05). Plasma LH concentrations measured every 6 h during the oestrous period in 38 'summer' cows were not significantly different for untreated and ventilated animals. Conception rate was higher (P less than 0.05) in cows that showed oestrous behaviour before the LH surge reached its peak than in cows in which oestrus coincided with or occurred later than the LH surge. Plasma progesterone levels measured in 62 cows during the oestrous cycle before the first insemination were higher in the winter than in the summer in multiparous, but not in primiparous, cows. Ventilation increased progesterone levels in multiparous and primiparous cows. Plasma oestradiol-17 beta levels did not differ between groups until 36 h before the onset of oestrus, when they remained at 4.75 pg/ml in winter and summer-ventilated cows but increased to 6.75 pg/ml in summer untreated cows (P less than 0.01). Significant negative correlations were found between oestradiol levels observed 12 h before to 12 h after the onset of oestrus and plasma progesterone concentration during both the preceding and the subsequent oestrous cycles.

Animals↗
PubMed1979

Fertility of dairy heifers given a commercial diet free of beta-carotene.

1. Dairy heifers given concentrates including vitamin A and wheat straw from 7 to 17 months of age had an average plasma beta-carotene concentration of 20--60 micrograms/l. Control heifers given the same diet but supplemented with beta-carotene had a beta-carotene plasma concentration of 630--2190 micrograms/l. 2. In contrast to previous findings no differences in duration of standing oestrus, length of oestrous cycle, plasma progesterone and luteinizing hormone (LH) concentrations and interval between LH peak and ovulation were observed between the groups. All the heifers conceived after one or two inseminations; conception rate being 69% for heifers given a diet free of beta-carotene and 78% for the controls. 3. Average rate of growth of heifers not supplemented with beta-carotene was 0.75+/-0.02 kg/d v. 0.81+/-0.02 kg/d for the controls (P less than or equal to 0.02). 4. The possible reasons for the discrepancy between present and previous findings are discussed.

Animals↗
PubMed1977

Seasonal variations in post-partum plasma progesterone levels and conception in primiparous and multiparous dairy cows.

Progesterone concentrations in peripheral plasma of 18 primiparous and 34 multiparous dairy cows were determined by radioimmunoassay every 4 days, from 10 days post partum until the next conception. The interval from parturition to the first progesterone peak (greater than 4 ng/ml plasma) was significantly longer (P less than 4 ng/ml plasma) was significantly longer (P less than 0.01) in primiparous than in multiparous cows. The progesterone concentrations on Days 4-15 of the oestrous cycle were significantly lower (P less than 0.025) during the summer than in cycles occurring in winter. The conception rate during the summer was lower than in winter. In cows inseminated in summer, conception was related to the shape of the progesterone curve in the cycle preceding insemination.

Animals↗