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Biomedical subjects

G B Anderson

Publications and source records attributed to G B Anderson.

At least 109 records · Page 6Linked to original sources
PubMed1983

Survival of bovine embryos stored at 4 degrees C.

These experiments were designed to test the efficacy of storing bovine embryos at 4 degrees C. Of particular interest were the age of embryo at which maximum post-storage survival could be achieved and longevity at 4 degrees C. A greater proportion of day 8 blastocysts developed in vitro at 37 degrees C following refrigeration for 48 hr than did embryos collected 2, 4 or 6 days after estrus (P<0.01). Survival of blastocysts stored at 4 degrees C for 48 hr was similar to that of nonstored blastocysts. In a subsequent experiment, day 8 blastocysts were recovered nonsurgically and assigned to one of the following treatments: (a) immediate transfer; (b) culture at 37 degrees C; or (c) storage at 4 degrees C for 1, 2, 3 or 5 days. Post-storage viability was assessed by either development in culture at 37 degrees C or embryo survival following nonsurgical transfer to synchronized recipients. In vitro survival of nonstored embryos and embryos stored 1 day did not differ. Survival decreased after storage for 2 days (P<0.10) or longer (P<0.05). Similar results were observed for survival after transfer, but embryo viability decreased even more rapidly with increasing duration of storage. In vitro survival was approximately 50% for blastocysts stored for 3 and 5 days, but few pregnancies resulted from transfer of embryos stored for these periods. In another experiment survival after transfer of blastocysts stored at 4 degrees C for up to 2 days was similar to that of nonstored blastocysts.

Journal Article↗
PubMed1983

Cytolytic and fluorescent detection of H-Y antigen on preimplantation mouse embryos.

Monoclonal antibodies to histocompatibility (H-Y) antigen, of IgM subclass, were used to immunologically determine the sex of mouse embryos prior to transfer to pseudopregnant recipients. Two experiments were performed, one using cytolysis of H-Y positive embryos and the other using binding of a Fluorescein Isothiocyanate-(FITC) labeled second antibody. Eight- to 16-cell embryos used in the cytolytic assay were cultured in Whitten's Medium without bovine serum albumin (WM), to which monoclonal antibody and normal guinea pig serum were added. Embryos were classified as affected or unaffected, based on morphology of the embryo and its blastomeres. A total of 550 embryos were cultured; 294 (53.5%) were scored as unaffected and 263 of these were transferred to recipients. Forty-three (81.1%) of 53 pups born were female. Morulae and early blastocysts were used in the FITC-labeled second antibody assay. Embryos were cultured in WM containing monoclonal antibody, washed and placed in drops of WM containing FITC-labeled anti-IgM. Following another wash embryos were individually evaluated at 200X for fluorescence. Fifty-five percent (169 of 305) of the embryos displayed cell-specific fluorescence. A total of twenty-three pups, 18 males (78.3%) and five females (21.7%), were born following transfer of 156 fluorescing embryos. Four male (17.4%) and nineteen female (82.6%) pups resulted from embryos classified as non-fluorescing.

Journal Article↗
PubMed1982

Short-term storage of rabbit embryos at 4 degrees C.

A simple method for storing preimplantation mammalian embryos was tested under conditions which could be easily maintained inside an ordinary refrigerator set at 4 degrees C. No significant loss of viability occurred when rabbit embryos were stored at 4 degrees C for 7 days and either cultured in vitro at 37 degrees C or transferred to recipient does. Significant losses occurred when embryos were stored for 10 days or longer before culture at 37 degrees C (P < .01). Stored embryos transferred to recipients had a significantly longer average gestation period than embryos transferred without cold storage (P < .05).

Journal Article↗
PubMed1982

Prolactin response in beef cows and heifers suckling one or two calves.

Blood was collected, at 5-min intervals for 3 h, via jugular cannulation every 14 days during the first 4 months post partum from beef cows and heifers, 4 suckling 2 calves and 4 suckling 1 calf. Calves were isolated from the dams to prevent suckling for approximately 4 h before and 2 1/2 h during sampling to obtain baseline values for prolactin, measured by radioimmunoassay. During the last 30 min of sampling, calves were allowed to suck. Milk samples were also collected at 28-day intervals from 60 females, 30 with twins and 30 with single calves. beginning 2 weeks after calving and continuing until calves were weaned at 180 days of age. No differences were observed between dams with 1 and 2 calves for baseline plasma prolactin level or for prolactin response to the suckling stimulus by 1 or 2 calves. However, milk prolactin concentration was significantly higher (P less than 0.01) for dams with 2 calves, probably reflecting the more frequent suckling that occurs with twins. Milk prolactin value in this study was not highly correlated with the post-partum interval to first ovulation from another study on these animals. It is concluded that prolactin is not significantly higher (P less than 0.01) for dams with 2 calves, probably reflecting the more frequent suckling that occurs with twins. Milk prolactin value in this study was not highly correlated with the post-partum interval to first ovulation from another study on these animals. It is concluded that prolactin is not significantly higher (P less than 0.01) for dams with 2 calves, probably reflecting the more frequent suckling that occurs with twins. Milk prolactin value in this study was not highly correlated with the post-partum interval to first ovulation from another study on these animals. It is concluded that prolactin is not the primary factor controlling the longer post-partum interval to first ovulation in beef cattle with twins.

Animals↗
PubMed1982

Maternal energy status of beef cattle during single and twin pregnancy.

A study was undertaken to determine the metabolizable energy (ME) intake and ME requirement for beef heifers and cows during twin pregnancy. Weekly feed consumption and body weights were recorded during the last trimester of twin pregnancy for 19 Hereford cows and 16 Hereford heifers. The same data were recorded for six Hereford cows and eight Hereford heifers that calved singles. ME intake per unit of metabolic body size was higher for heifers than cows (P less than .05), but was not affected by whether the dam was pregnant with a single or with twins. In general, ME intake decreased during the last trimester of pregnancy. During this time, heifers and cows with singles gained weight (pregnant weight minus weight of the conceptus), while dams with twins lost weight (P less than .01). The greatest weight loss for dams with twins was observed late in pregnancy. The ME requirement of pregnancy was greater for dams with twins than singles (P less than 0.01), and the difference in maintenance ME requirement approached significance (P less than .10). The high ME requirement for the twin pregnancy and the weight loss experienced by dams during the last trimester may have implications for management decisions pertaining to the prevention of complications that often occur with twin pregnancy in cattle.

Animals↗
PubMed1982

Induction of twins in different breeds of cattle.

Two experiments were conducted examining bilateral transfer of Hereford X Angus crossbred embryos to Angus, Hereford and Hereford x Angus crossbred recipients. In Exp. 1, both virgin heifers and parous cows were used as recipients, in Exp. 2, only virgin heifers were used. No differences in production of twins due to breed of recipient was observed. In Exp. 1, heifers had as high a twinning rate and proportion of pregnancies carried to term as cows. About 9% of the heifers in Exp. 2 experienced late gestation abortion (based on recipients pregnant at 42 d), a problem which was not observed among heifers in Exp. 1. No association between body weight at transfer and abortion was observed. Twin pregnancy was associated with a higher incidence of retained placentas (Exp. 1, P less than .05; Exp. 2, P less than .10), lower birth weight/calf (P less than .01 in both experiments) and shorter gestation period (P less than .01 in both experiments). Calf mortality at birth was similar among twins and singles and, in Exp. 2, a lower (P less than .02) incidence of dystocia was observed among heifers giving birth to twins than among those with single calves. The results of these experiments indicate that both beef heifers and beef cows of three common breed types are capable of maintaining twin pregnancies and successfully producing twins.

Abortion, Veterinary↗
PubMed1982

Postpartum ovarian function and fertility in beef cattle that produce twins.

A study was conducted to determine the effect of suckling on ovarian function and postpartum reproductive performance in beef cattle induced to produce twins by embryo transfer. This study involved 31 pluriparous Hereford, Angus and Hereford X Angus crossbred cows and 24 Hereford, Angus and Hereford X Angus crossbred heifers. Seventeen of the cows and 16 of the heifers calved twins, and the remainder produced single calves. From 45 d postpartum, the dams were exposed to three Hereford bulls until pregnancy was confirmed. The first postpartum ovulation was estimated from an increase in serum progesterone level. The interval to first postpartum ovulation was slightly, but not significantly longer for dams that calved and suckled twins than for dams that calved and suckled singles or calved twins and suckled singles (50.7 +/- 3.1, 43,5 +/- 3.4, and 37.7 +/- 5.6 d, respectively). This delay, however, did not significantly affect the number of days to conception for dams that suckled or calved twin or single calves. Once estrous cycles were initiated, the interval to conception for dams with twins was similar to that for dams with single calves. Under the management scheme used, postpartum ovulation and conception in beef heifers and cows were not significantly reduced by the production of twins.

Animals↗
PubMed1982

Maternal influences on growth of twin and single calves.

Milk production was measured at 28-d intervals by the calf weight change method in 30 dams with twins and in 28 dams with single calves. Average adjusted 170-d weaning weights for twins were between 41 and 38 kg less than for singles (depending on linear contrast). Yet dams with twins weaned between 91 and 97 kg more calf and produced substantially more milk. Significant dam breed and parity differences in calf growth and weaning weight were observed among twins. Dam breeds ranked in the order of decreasing productivity were Hereford-Angus crossbred, Angus and Hereford. Cows outproduced heifers. Among singles, such differences were small. As indicated by linear contrasts, maternal effects were larger in twins than in singles; however, these differences were generally not significant. Only milk production in the first half of lactation by dams with twins was found to be a significant predictor of calf growth and weaning weight. For every 1-kg increase in 6-h milk production in early lactation, 170-d adjusted weaning weight of twins increased (P less than .01) by 18.8 kg. Among singles, regression estimates for growth on milk yield were small and nonsignificant.

Animals↗
PubMed1981

Length of gestation in ewes carrying lambs of two different breeds.

Length of gestation was studied in pregnancies established by intrabreed, interbreed, and mixed-breed embryo transfers of Finnish Landrace (Finn; mean gestation: 144.9 days) and Targhee (mean gestation: 150.4 days) embryos to Finn cross and Targhee recipients. At least one lamb of each breed comprised mixed-breed pregnancies. There was a significant effect of the breed of lamb (Finn, Targhee, or Finn and Targhee) on the length of gestation (P<.01), but not of breed of recipient. Mixed-breed pregnancies had a mean gestation period intermediate between those for pregnancies which contained only one breed of lamb. The mean gestation period for mixed-breed pregnancies was 2.10+/-.70 (x+/-S.E.) days longer than for pregnancies with only Finn lambs (P<.01) and 2.99+/-.73 days shorter than for pregnancies with only Targhee lambs (P<.001). The delay in parturition in mixed-breed pregnancies beyond the normal gestation period for Finn lambs occurred even in litters with a majority of Finn lambs. These results demonstrate an interaction between fetuses in the processes leading to parturition. Possible mechanisms by which the Targhee lamb delayed parturition in mixed-breed pregnancies are discussed.

Journal Article↗
PubMed1980

Effects of maternal and embryonic genotype on prenatal survival in two selected mouse lines.

The effect of fetal and maternal genotype on embryo survival was studied in two lines of mice from the same base population: line E, selected for high embryo survival, and line CN-, selected for small litter size. Embryos were collected at 3.5 days postcoitus from normally mated donors of both lines and were transferred to the uteri of 2.5-day pseudopregnant recipients from each line. The number of embryos recovered and the proportion of those recovered that had been fertilized were greater in line E donors than in line CN- donors (P < .05). Development into blastocysts was slower for CN- embryos. The proportion of recipient females that were pregnant was higher for line E than for line CN- after transfer of line E embryos (P < .005). The same trend was observed following transfer of line CN- embryos (P < .10). Embryos of both lines showed greater survival when transferred to line E recipients than when transferred to line CN- recipients (P < .005), and, within line E recipients, E embryos tended to survive better than did CN- embryos (P < .10). The results suggest that although the genotype of the embryo may play a role, the maternal genotype has greater influence on embryo survival in the two lines of mice.

Animals↗
PubMed1979

A simple technique for nonsurgical embryo transfer in mice.

A simple method was developed for nonsurgical transfer of mouse embryos which enabled transfer to both uterine horns. Embryos were picked up in a modified capillary tube and transferred through the cervix into each uterine horn of an unanesthetized mouse. A glass speculum was used to facilitate location of the cervix. The technique was found to be as successful (up to 60% of embryos transferred developed to term) as surgical methods yet was simpler and eliminated surgical trauma to the recipient mouse.

Animals↗
PubMed1976

A study of anaesthesia depth by power spectral analysis of the electroencephalogram (EEG).

The feasibility of using computer-based EEG spectral analysis to monitor the level of anaesthesia during nitrous oxide-alphaprodine anaesthesia has been established by this study. At present, this system is capable of estimating the level of anaesthesia correctly from 55 per cent to 80 per cent of the time. There are several possible clinical applications of such a monitoring system during anaesthesia. It provides a continuous estimation of the depth of anaesthesia, without requiring any special EEG training on the part of the anaesthetist. This system can also be of particular benefit during anaesthesia for critically ill patients, or in specific cases, as in neurosurgery and caesarian section when there may be periods of time when the gross clinical evaluation of depth of anaesthesia may not be precise or reliable and yet it is imperative not to deepen the anaesthesia unnecessarily. In such instances it appears that a monitoring system such as we have developed could provide valuable indication of the depth of anaesthesia. Other potential applications might be in the training of students in the clinical assessment of patients during anaesthesia and in the study of new anaesthetic agents.

Adult↗