Biomedical subjects

C H Mickelsen

Publications and source records attributed to C H Mickelsen.

4 recordsLinked to original sources

PubMed1987

Factors affecting survivability of transferred whole and demi-embryos in a commercial dairy herd.

Sixty Holstein donor cows were superovulated and embryos were collected during a 6-d (27 cows) and a 4-d (33 cows) period approximately 60 d apart. Forty-three donor cows yielded embryos. Ninety-one embryos graded 1 or 2 were split and transferred to 181 recipient Holsteins. Demi-embryos were graded 2, 2-, 3 and 3- prior to transfer. Pregnancy and calving percentages were similar for all demi-embryo grades, averaging 59 and 53% from the two donor groups, respectively. Twin demi-embryo pregnancies averaged 36 and 19% for embryos split at the compacted morula and blastocyst stages, respectively. Twin demi-embryo calvings averaged 30 and 15% for these same groups. Progesterone levels of recipients (of either whole or demi-embryos) of second period donors were measured. Pregnancy rate increased generally with level of progesterone; however, calving percentage was slightly greater for recipients with intermediate levels of progesterone (2-6 ng/ml). Multiparous cow (20) recipients of demi-embryos had 45% pregnancy and 40% calving, while nulliparous heifer (161) recipients averaged 59 and 53% pregnancy and calving, respectively.

Journal Article↗

PubMed1985

Effect of early rearing experience on subsequent behavior and production of Holstein heifers.

Sixty-seven heifer calves were assigned at birth to one of four rearing treatments: groups of six, individual hutch, isolation, and isolation with handling (10 min daily interaction with calf feeder). Calves were on the same diet and except for group calves were in 1.2 X 2.4-m hutches. Group calves were in open shed housing with 3m2/calf. Calves were weaned at approximately 10 wk and then assimilated into regular herd routine. An open field test of 3 min for each calf was conducted on 3 consecutive days at weaning. Samples for blood plasma glucocorticoids were taken before and after open field testing. Forty-eight heifers milked twice daily completed 305-day lactations. There were no differences in weaning weight or average daily gain to weaning. Group calves urinated and defecated more during open field tests, but number of vocalizations was not different. There was a significant rise of glucocorticoids for all calves, but treatment effects were nil. Cows reared in isolation (treatments 3 and 4) produced significantly more milk (922 kg 3.5% fat-corrected milk), had a 1205 kg advantage in relative milk, but were not different from group or individually reared cows in relative milk fat. A hypothesis to explain these results is proposed.

Age Factors↗

PubMed1977

Effects of dominance rank changes, age, and body weight on plasma corticoids of mature dairy cattle.

The purpose was to determine whether forced change in dominance rank affected total corticoids of plasma of dairy cattle. Nineteen cows in late lactation were assigned randomly to one of two lots. Restriction of manger space enhanced observations of dominance rank during feeding for three 1-h periods per wk over 6 wk. After 3 wk, a group of the five highest ranking cows from each lot were combined into a new aggressive lot; two groups of subordinate cows formed a docile lot. Blood samples were from tail vein, and concentrations of total corticoids were determined by competitive protein binding. Changes of dominance rank varied from zero to eight places in the 10-cow assemblage after new lots were formed. Body weight was the most significant variable affecting dominance rank. There was no discernable relationship between total corticoids and dominance rank, body weight, or age. The pattern of variation of total corticoids was similar for all groups during the first 3-wk period, but in the second period docile and aggressive groups had dissimilar patterns. Interaction of group by week for total corticoids was significant; however, a cause and effect relationship could not be established. Total corticoids did not appear to be a valid or useful determinant of social stress.

Adrenal Cortex Hormones↗

PubMed1977

Facility for exercising dairy cows.

That dairy cows housed in confinement might benefit if they were exercised during the dry period prompted development of a facility for exercising dairy cows. Two methhods of the exerciser, which consist of a circular lane and a driving mechanism powered by a variable speed electric motor, are described. A speed of 3.5 k, per h provides a steady but comfortable pace for pregnant dairy cows and heifers. Many animals refused to go at speeds greater than 5.5 km per h.

Animals↗