Biomedical subjects

B W Kirkpatrick

Publications and source records attributed to B W Kirkpatrick.

59 records · Page 4Linked to original sources

PubMed1988

Influences of prenatal and postnatal fraternity size on ovarian development in the mouse.

An experiment was conducted to test effects of prenatal and postnatal fraternity size (size of litter in which an individual develops prenatally or is reared postnatally) on ovarian development in mice. Fraternity size treatments were created by standardizing sizes of prenatal and postnatal fraternities in which mice were gestated and reared. Prenatal fraternity size was standardized by surgery on Day 9 of gestation to 6, 10, and 14 fetuses. Postnatal fraternity size was standardized by randomly assigning pups to litters of 5, 10, or 15 pups within 24 h of birth. Female pups were killed at either 3 or 20 wk of age and right ovaries were prepared for histology. Follicles were classified by size and morphology, and numbers of follicles in each class were tabulated. Interaction of postnatal fraternity size and age was observed for number of antral follicles (p less than 0.05). Mice reared in small postnatal fraternities had more antral follicles at weaning (3 wk) and fewer antral follicles at maturity (20 wk of age) than mice reared in large postnatal fraternities. No effect of either prenatal or postnatal fraternity size on other follicle populations was observed (p greater than 0.20). Numbers of Type 2 (primordial), Type 3a, and Type 3b follicles changed with age (p less than 0.01); numbers of primordial follicles declined with age, but numbers of Type 3a and 3b follicles increased. A hypothesis of a negative association between postnatal fraternity size and number of antral follicles at 3 wk of age was supported, but a hypothesis of a positive association between fraternity size and number of primordial follicles was not supported.

Animals↗

PubMed1988

Influence of prenatal and postnatal fraternity size on reproduction in swine.

Hypotheses of a negative association between fraternity size (size of litter in which an individual develops prior to birth or is reared following birth) and ovulation rate or litter size were tested by examining reproduction of females born or reared in varying prenatal and postnatal fraternities. Gifts were randomly assigned to develop prenatally and be reared postnatal in small or large fraternities. Dams of experimental animals were randomly assigned to one of two prenatal fraternity size treatments, either unilateral oviductal ligation (to bear a small prenatal litter) or no ligation (to bear a normal prenatal litter). Whereas this did result in differences (P less than .01) in litter size at birth (small = 6.2 +/- .4 vs large = 9.6 +/- .9), there was considerable overlap in observed litter sizes between ligated and nonligated dams. Consequently, effects of prenatal fraternity size were examined by regression. Distinct differences in postnatal fraternity size were created by randomly assigning piglets to small (5 piglets) or large (10 piglets) postnatal fraternities within 24 h of birth. Differences in postnatal fraternity size were maintained through weaning at 3 wk (small = 4.9 +/- .1 vs large = 9.4 +/- .2). Weights at birth (regression of birth weight on prenatal fraternity size = -.07 +/- .02, P less than .01) and weaning (small = 6.09 +/- .15 vs large = 5.46 +/- .17 kg, P less than .01) were heavier for gilts from small prenatal and postnatal fraternities, respectively, compared with gilts from large fraternities. Effects of prenatal and postnatal size on BW did not persist following weaning (P greater than .20).

Animals↗

PubMed1988

Effects of prenatal and postnatal fraternity size on long-term reproduction in mice.

Effects of prenatal and postnatal fraternity size (size of litter in which an animal develops prior to birth or is reared following birth) on long-term reproduction were studied by rearing 178 female ICR mice in standardized prenatal and postnatal fraternities. Three levels of prenatal and postnatal fraternity sizes were used in a 3 x 3 factorial experiment. Prenatal fraternity size was standardized by selectively terminating fetal development in pregnant females carrying at least 14 conceptuses. Prenatal fraternities were standardized to either 6, 10 or 14 fetuses, and postnatal fraternities were standardized by randomly assigning individuals to nurse litters of 5, 10 or 15 pups. Prenatal fraternity size negatively affected average pup weight at birth (P less than .05) but had little subsequent effect on growth or reproduction. Postnatal fraternity size negatively affected weight at weaning (P less than .01), with mice reared in smaller postnatal fraternities being heavier than those reared in larger fraternities. Following weaning, mice reared in smaller fraternities gained weight less rapidly (P less than .01) but still tended to be heavier at maturity (P = .11). Vaginal opening occurred at older ages in females reared in larger postnatal litters (P less than .01). An interval mating system was used to examine fraternity size effects on long-term reproduction. Females were exposed to males six times at 8-wk intervals with initial mating at 7 wk of age. Postnatal fraternity size and age at mating jointly affected litter size (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

An alternative model for additive and cytoplasmic genetic and maternal effects on lactation.

Results from a recent study that presented evidence suggesting a lack of cytoplasmic inheritance of lactation traits were reexamined using a model that included effects of additive genotype, cytoplasmic genotype, their interaction, and maternal influences. Under this model, equivalent estimates of heritability from daughter-dam and grand-daughter-grand-dam regression that exceed those from paternal half-sib correlation were consistent with the presence of cytoplasmic inheritance. A definitive answer to the question of cytoplasmic inheritance of lactation traits awaits a designed experiment, likely employing transfer of identical nuclei into varying cytoplasmic backgrounds.

Animals↗

PubMed1987

The influence of prenatal and postnatal fraternity size on reproduction in mice.

Effects of prenatal and postnatal fraternity size (size of litter in which an individual is reared) on age at vaginal opening, growth, and subsequent litter production were examined by rearing mice in standardized prenatal and postnatal fraternities in a 3 X 3 factorial design. Prenatal fraternity size was standardized by reducing litters of 14 or more to either 14, 10, or 6 fetuses on Day 9 of gestation. Postnatal fraternity size was standardized by assigning pups randomly to nurse in litters of 5, 10, or 15 pups within 24 h of birth. Both prenatal and postnatal fraternity size affected growth of the mice (p = 0.02 and p less than 0.01, respectively) with mice reared in small fraternities attaining greater weights throughout the study. Prenatal fraternity size had a negative linear effect on litter size at second parity and tended to have a positive linear effect on age at vaginal opening. Postnatal fraternity size affected age at vaginal opening (p less than 0.01), litter size at first parity (p less than 0.01), and litter size at second parity (p = 0.03). These effects were positive and linear for age at vaginal opening (p less than 0.01; small fraternity size associated with younger age at vaginal opening) and negative and linear for litter size at first and second parity (p less than 0.01 and p = 0.10, respectively; smaller fraternity size associated with larger litter size). There was no interaction between prenatal and postnatal fraternity size effects on age at vaginal opening or litter size (p greater than 0.20).

Aging↗